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Pereira AJ, Xing H, de Campos LJ, Seleem MA, de Oliveira KMP, Obaro SK, Conda-Sheridan M. Structure-Activity Relationship Study to Develop Peptide Amphiphiles as Species-Specific Antimicrobials. Chemistry 2024; 30:e202303986. [PMID: 38221408 PMCID: PMC10939825 DOI: 10.1002/chem.202303986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 01/05/2024] [Accepted: 01/09/2024] [Indexed: 01/16/2024]
Abstract
Antimicrobial peptide amphiphiles (PAs) are a promising class of molecules that can disrupt the bacterial membrane or act as drug nanocarriers. In this study, we prepared 33 PAs to establish supramolecular structure-activity relationships. We studied the morphology and activity of the nanostructures against different Gram-positive and Gram-negative bacterial strains (such as Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Acinetobacter baumannii). Next, we used principal component analysis (PCA) to determine the key contributors to activity. We found that for S. aureus, the zeta potential was the major contributor to the activity while Gram-negative bacteria were more influenced by the partition coefficient (LogP) with the following order P. aeruginosa>E. coli>A. baumannii. We also performed a study of the mechanism of action of selected PAs on the bacterial membrane assessing the membrane permeability and depolarization, changes in zeta potential and overall integrity. We studied the toxicity of the nanostructures against mammalian cells. Finally, we performed an in vivo study using the wax moth larvae to determine the therapeutic efficacy of the active PAs. This study shows cationic PA nanostructures can be an intriguing platform for the development of nanoantibacterials.
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Affiliation(s)
- Aramis J. Pereira
- A. J. Pereira, Dr. H. Xing, L. J. de Campos, Prof. Dr. M. Conda-Sheridan, Department of Pharmaceutical Sciences, University of Nebraska Medical Center (UNMC), Omaha, NE 68198 (USA)
| | - Huihua Xing
- A. J. Pereira, Dr. H. Xing, L. J. de Campos, Prof. Dr. M. Conda-Sheridan, Department of Pharmaceutical Sciences, University of Nebraska Medical Center (UNMC), Omaha, NE 68198 (USA)
| | - Luana J. de Campos
- A. J. Pereira, Dr. H. Xing, L. J. de Campos, Prof. Dr. M. Conda-Sheridan, Department of Pharmaceutical Sciences, University of Nebraska Medical Center (UNMC), Omaha, NE 68198 (USA)
| | - Mohamed A. Seleem
- Dr. M.A. Seleem, Department of Pharmaceutical Organic Chemistry, Al-Azhar University, Cairo, 4434003 (Egypt)
| | - Kelly M. P. de Oliveira
- Prof. Dr. K. M. P. de Oliveira, Department of Biological and Environmental Science, Federal University of Grande Dourados (UFGD), Dourados, MS 79804-970 (Brazil)
| | - Stephen K. Obaro
- Prof. Dr. S. K. Obaro, Division of Pediatric Infectious Diseases, University of Alabama at Birmingham (UAB), Birmingham, AL 35233 (USA), International Foundation against Infectious Diseases in Nigeria (IFAIN), Abuja, 900108 (Nigeria)
| | - Martin Conda-Sheridan
- A. J. Pereira, Dr. H. Xing, L. J. de Campos, Prof. Dr. M. Conda-Sheridan, Department of Pharmaceutical Sciences, University of Nebraska Medical Center (UNMC), Omaha, NE 68198 (USA)
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Michelow IC, Obaro SK. Unraveling Neonatal Sepsis: Sharper Tools Needed for Unexpected Organisms. Clin Infect Dis 2023; 77:776-778. [PMID: 37279599 DOI: 10.1093/cid/ciad338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 05/23/2023] [Accepted: 06/01/2023] [Indexed: 06/08/2023] Open
Affiliation(s)
- Ian C Michelow
- Pediatrics and Infectious Diseases, Connecticut Children's Medical Center, University of Connecticut School of Medicine, Connecticut, CT, USA
| | - Stephen K Obaro
- Pediatrics and Infectious Diseases, University of Nebraska Medical Center, Omaha, NE, USA
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3
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Lo SW, Hawkins PA, Jibir B, Hassan-Hanga F, Gambo M, Olaosebikan R, Olanipekun G, Munir H, Kocmich N, Rezac-Elgohary A, Gambo S, Bagenda D, Fey P, Breiman RF, McGee L, Bentley SD, Obaro SK. Molecular characterization of Streptococcus pneumoniae causing disease among children in Nigeria during the introduction of PCV10 (GSK). Microb Genom 2023; 9:001094. [PMID: 37712828 PMCID: PMC10569732 DOI: 10.1099/mgen.0.001094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 08/03/2023] [Indexed: 09/16/2023] Open
Abstract
Streptococcus pneumoniae (pneumococcus) is a leading vaccine-preventable cause of childhood invasive disease. Nigeria has the second highest pneumococcal disease burden globally, with an estimated ~49 000 child deaths caused by pneumococcal infections each year. Ten-valent pneumococcal conjugate vaccine (GSK; PCV10) was introduced in December 2014 in a phased approach. However, few studies have characterized the disease-causing pneumococci from Nigeria. This study assessed the prevalence of serotypes, antibiotic susceptibility and genomic lineages using whole genome sequencing and identified lineages that could potentially escape PCV10 (GSK). We also investigated the potential differences in pneumococcal lineage features between children with and without sickle cell disease. A collection of 192 disease-causing pneumococcal isolates was obtained from Kano (n=189) and Abuja (n=3) states, Nigeria, between 1 January 2014 and 31 May 2018. The majority (99 %, 190/192) of specimens were recovered from children aged 5 years or under. Among them, 37 children had confirmed or traits of sickle cell disease. Our findings identified 25 serotypes expressed by 43 Global Pneumococcal Sequence Clusters (GPSCs) and 85 sequence types (STs). The most common serotypes were 14 (18 %, n=35), 6B (16 %, n=31), 1 (9 %, n=17), 5 (9 %, n=17) and 6A (9 %, n=17); all except serotype 6A are included in PCV10 (GSK). PCV10 (SII; PNEUMOSIL) and PCV13 formulations include serotypes 6A and 19A which would increase the overall coverage from 67 % by PCV10 (GSK) to 78 and 82 %, respectively. The pneumococcal lineages were a mix of globally spreading and unique local lineages. Following the use of PCV10 (GSK), GPSC5 expressing serotype 6A, GPSC10 (19A), GPSC26 (12F and 46) and GPSC627 (9L) are non-vaccine type lineages that could persist and potentially expand under vaccine-selective pressure. Approximately half (52 %, 99/192) of the pneumococcal isolates were resistant to the first-line antibiotic penicillin and 44 % (85/192) were multidrug-resistant. Erythromycin resistance was very low (2 %, 3/192). There was no significant difference in clinical manifestation, serotype prevalence or antibiotic resistance between children with and without traits of or confirmed sickle cell disease. In summary, our findings show that a high percentage of the pneumococcal disease were caused by the serotypes that are covered by currently available vaccines. Given the low prevalence of resistance, macrolide antibiotics, such as erythromycin, should be considered as an option to treat pneumococcal disease in Nigeria. However, appropriate use of macrolide antibiotics should be vigilantly monitored to prevent the potential increase in macrolide resistance.
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Affiliation(s)
- Stephanie W. Lo
- Parasites and Microbes, Wellcome Sanger Institute, Hinxton, UK
| | | | - Binta Jibir
- Hasiya Bayero Pediatric Hospital, Kano, Nigeria
| | | | | | - Rasaq Olaosebikan
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA, USA
| | - Grace Olanipekun
- International Foundation against Infectious Diseases in Nigeria, Abuja, Nigeria
| | - Huda Munir
- Aminu Kano Teaching Hospital, Kano, Nigeria
| | - Nicholas Kocmich
- Division of Pediatric Infectious Disease, University of Nebraska Medical Center, Omaha, NE, USA
| | - Amy Rezac-Elgohary
- Division of Pediatric Infectious Disease, University of Nebraska Medical Center, Omaha, NE, USA
| | - Safiya Gambo
- Murtala Muhammad Specialist Hospital, Kano, Nigeria
| | - Danstan Bagenda
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Paul Fey
- University of Nebraska Medical Center, Department of Pathology and Microbiology, Omaha, Nebraska, USA
| | - Robert F. Breiman
- Emory Global Health Institute, Emory University, Atlanta, GA, USA
- Rollins School Public Health, Emory University, Atlanta, GA, USA
| | - Lesley McGee
- Centers for Disease Control and Prevention, Atlanta, GA, USA
| | | | - Stephen K. Obaro
- Aminu Kano Teaching Hospital, Kano, Nigeria
- International Foundation against Infectious Diseases in Nigeria, Abuja, Nigeria
- Division of Pediatric Infectious Disease, University of Nebraska Medical Center, Omaha, NE, USA
- University of Nebraska Medical Center, Department of Pathology and Microbiology, Omaha, Nebraska, USA
- Pediatric - Infectious Disease, School of Medicine, The University of Alabama, Birmingham, AL, USA
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Battalapalli D, Chakraborty P, Jain D, Obaro SK, Gurkan UA, Bonomo RA, Draz MS. Polyethylene Glycol-Mediated Directional Conjugation of Biological Molecules for Enhanced Immunoassays at the Point-of-Care. Polymers (Basel) 2023; 15:3316. [PMID: 37571209 PMCID: PMC10422345 DOI: 10.3390/polym15153316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 07/26/2023] [Accepted: 07/28/2023] [Indexed: 08/13/2023] Open
Abstract
Rapid and reliable point-of-care (POC) diagnostic tests can have a significant impact on global health. One of the most common approaches for developing POC systems is the use of target-specific biomolecules. However, the conjugation of biomolecules can result in decreased activity, which may compromise the analytical performance and accuracy of the developed systems. To overcome this challenge, we present a polymer-based cross-linking protocol for controlled and directed conjugation of biological molecules. Our protocol utilizes a bifunctional thiol-polyethylene glycol (PEG)-hydrazide polymer to enable site-directed conjugation of IgG antibodies to the surface of screen-printed metal electrodes. The metal surface of the electrodes is first modified with thiolated PEG molecules, leaving the hydrazide groups available to react with the aldehyde group in the Fc fragments of the oxidized IgG antibodies. Using anti-Klebsiella pneumoniae carbapenemase-2 (KPC-2) antibody as a model antibody used for antimicrobial resistance (AMR) testing, our results demonstrate a ~10-fold increase in antibody coupling compared with the standard N-hydroxysuccinimide (NHS)-based conjugation chemistry and effective capture (>94%) of the target KPC-2 enzyme antigen on the surface of modified electrodes. This straightforward and easy-to-perform strategy of site-directed antibody conjugation can be engineered for coupling other protein- and non-protein-based biological molecules commonly used in POC testing and development, thus enhancing the potential for improved diagnostic accuracy and performance.
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Affiliation(s)
| | - Purbali Chakraborty
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Disha Jain
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Stephen K. Obaro
- Division of Pediatric Infectious Diseases, Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Umut A. Gurkan
- Mechanical and Aerospace Engineering Department, Case Western Reserve University, Cleveland, OH 44106, USA
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Robert A. Bonomo
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH 44106, USA
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology, Cleveland, OH 44106, USA
| | - Mohamed S. Draz
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH 44106, USA
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- Department of Biomedical Engineering, Cleveland Clinic, Cleveland, OH 44106, USA
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5
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Maloney P, Mowrer C, Jansen L, Karre T, Bedrnicek J, Obaro SK, Iwen PC, McCutchen E, Wetzel C, Frederick J, Ashraf MS, Donahue M. Fatal Primary Amebic Meningoencephalitis in Nebraska: Case Report and Environmental Investigation, August 2022. Am J Trop Med Hyg 2023; 109:322-326. [PMID: 37460088 PMCID: PMC10397427 DOI: 10.4269/ajtmh.23-0211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 05/10/2023] [Indexed: 08/04/2023] Open
Abstract
Primary amebic meningoencephalitis (PAM) is a rare and lethal infection caused by Naegleria fowleri. We report an epidemiological and environmental investigation relating to a case of PAM in a previously healthy boy age 8 years. An interview of the patient's family was conducted to determine the likely exposure site and to assess risk factors. Data from the United States Geological Survey site at Waterloo, NE, on the Elkhorn River were used to estimate water temperature and streamflow at the time and site of exposure. Data from the National Weather Service were used to estimate precipitation and ambient air temperature at the time and site of exposure. Despite conventional treatment, the patient died 2 days after hospital admission. The patient participated in recreational water activities in the Elkhorn River in northeastern Nebraska 5 days before symptom onset. In the week before exposure, water and ambient air high temperatures reached annual highs, averaging 32.4°C and 35.8°C, respectively. The day before infection, 2.2 cm of precipitation was reported. Streamflow was low (407 ft3/s). Infections in several northern states, including Nebraska, suggest an expanding geographic range of N. fowleri transmission, which may lead to increased incidence of PAM in the United States. Similar environmental investigations at suspected exposure sites of future cases will allow data aggregation, enabling investigators to correlate environmental factors with infection risk accurately.
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Affiliation(s)
- Patrick Maloney
- Nebraska Department of Health and Human Services, Lincoln, Nebraska
- University of Nebraska Medical Center, Omaha, Nebraska
| | - Clayton Mowrer
- University of Nebraska Medical Center, Omaha, Nebraska
- Children’s Hospital and Medical Center, Omaha, Nebraska
| | - Lauren Jansen
- Nebraska Department of Health and Human Services, Lincoln, Nebraska
- Centers for Disease Control and Prevention, Division of Workforce Development, Atlanta, Georgia
| | - Tess Karre
- Children’s Hospital and Medical Center, Omaha, Nebraska
| | | | | | | | | | - Chad Wetzel
- Douglas County Health Department, Omaha, Nebraska
| | | | - Muhammad Salman Ashraf
- Nebraska Department of Health and Human Services, Lincoln, Nebraska
- University of Nebraska Medical Center, Omaha, Nebraska
| | - Matthew Donahue
- Nebraska Department of Health and Human Services, Lincoln, Nebraska
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Doganay MT, Chelliah CJ, Tozluyurt A, Hujer AM, Obaro SK, Gurkan U, Patel R, Bonomo RA, Draz M. 3D Printed Materials for Combating Antimicrobial Resistance. Mater Today (Kidlington) 2023; 67:371-398. [PMID: 37790286 PMCID: PMC10545363 DOI: 10.1016/j.mattod.2023.05.030] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Three-dimensional (3D) printing is a rapidly growing technology with a significant capacity for translational applications in both biology and medicine. 3D-printed living and non-living materials are being widely tested as a potential replacement for conventional solutions for testing and combating antimicrobial resistance (AMR). The precise control of cells and their microenvironment, while simulating the complexity and dynamics of an in vivo environment, provides an excellent opportunity to advance the modeling and treatment of challenging infections and other health conditions. 3D-printing models the complicated niches of microbes and host-pathogen interactions, and most importantly, how microbes develop resistance to antibiotics. In addition, 3D-printed materials can be applied to testing and delivering antibiotics. Here, we provide an overview of 3D printed materials and biosystems and their biomedical applications, focusing on ever increasing AMR. Recent applications of 3D printing to alleviate the impact of AMR, including developed bioprinted systems, targeted bacterial infections, and tested antibiotics are presented.
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Affiliation(s)
- Mert Tunca Doganay
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Cyril John Chelliah
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Abdullah Tozluyurt
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Andrea M Hujer
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, USA
| | | | - Umut Gurkan
- Mechanical and Aerospace Engineering Department, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio, USA
| | - Robin Patel
- Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology and Division of Public Health, Infectious Diseases, and Occupational medicine, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Robert A Bonomo
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, USA
- Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES) Cleveland, OH, USA
| | - Mohamed Draz
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio, USA
- Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, USA
- Department of Biomedical Engineering, Cleveland Clinic, Cleveland, OH 44106, USA
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7
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Medugu N, Tickler IA, Duru C, Egah R, James AO, Odili V, Hanga F, Olateju EK, Jibir B, Ebruke BE, Olanipekun G, Tenover FC, Obaro SK. Phenotypic and molecular characterization of beta-lactam resistant Multidrug-resistant Enterobacterales isolated from patients attending six hospitals in Northern Nigeria. Sci Rep 2023; 13:10306. [PMID: 37365355 DOI: 10.1038/s41598-023-37621-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 06/24/2023] [Indexed: 06/28/2023] Open
Abstract
Infections caused by multi-drug resistant Enterobacterales (MDR-E) are difficult to treat and cause significant mortality, especially in developing countries. This study characterized the phenotypic and genotypic profiles of 49 randomly selected beta-lactam resistant MDR-E previously isolated from patients being managed in hospitals in Nigeria using whole genome sequencing. The study isolates exhibited 85.5% resistance to 3rd generation cephalosporins and 65.3% resistance to carbapenems. The blaTEM-1B (29, 59.2%), blaCTX-M-15 (38, 77.6%), and blaNDM-1 (17, 51.5%) were the most common penicillinase, ESBL, and carbapenem resistant genes across isolates, respectively. Seventeen (45%) of blaCTX-M-15 was carried on the insertion sequence ISEc9 while blaNDM-1 (11, 64.7%) were associated with ISEc33. None of the 21 plasmids detected were associated with β-lactamase genes. Higher resistance rates were found in E. coli ST-88 (n = 2) and the high-risk ST-692 (n = 2). For Klebsiella species, the high-risk clones ST-476 (n = 8) and ST-147 (n = 3) predominated and had higher phenotypic resistance rates and higher number of AMR genes. The mechanisms and pattern of antibiotic resistance differ from patterns previously described with isolates harbouring a wide range of AMRGs. The detection of several chromosomally mediated carbapenemases in our study also represents a significant finding that warrants further investigation to better understand its' implications for clinical practice and public health. The selected MDR-Es were found to be pan-susceptible to tigecycline and had very low resistance to fosfomycin, suggesting a potential for these as empiric treatments. A surveillance approach incorporating both conventional laboratory techniques and modern molecular techniques is essential for the comprehensive characterization of the emergence and dissemination of antimicrobial resistance in Enterobacterales infections within Nigeria.
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Affiliation(s)
- Nubwa Medugu
- Nile University of Nigeria, Cadastral Zone, Research and Institutions Area, Abuja, Nigeria.
- International Foundation Against Infectious Disease in Nigeria, Dutse Street, Gwarinpa, Abuja, Nigeria.
| | | | - Carissa Duru
- Nile University of Nigeria, Cadastral Zone, Research and Institutions Area, Abuja, Nigeria
| | - Ruth Egah
- Nile University of Nigeria, Cadastral Zone, Research and Institutions Area, Abuja, Nigeria
| | - Abu Ocheiku James
- Nile University of Nigeria, Cadastral Zone, Research and Institutions Area, Abuja, Nigeria
| | - Vivian Odili
- Nile University of Nigeria, Cadastral Zone, Research and Institutions Area, Abuja, Nigeria
| | | | | | - Binta Jibir
- Hasiya Bayero Children's Hospital, Kano, Nigeria
| | - Bernard E Ebruke
- Nile University of Nigeria, Cadastral Zone, Research and Institutions Area, Abuja, Nigeria
| | - Grace Olanipekun
- Nile University of Nigeria, Cadastral Zone, Research and Institutions Area, Abuja, Nigeria
| | - Fred C Tenover
- College of Arts and Sciences, University of Dayton, Dayton, OH, 45469, USA
| | - Stephen K Obaro
- Nile University of Nigeria, Cadastral Zone, Research and Institutions Area, Abuja, Nigeria
- University of Nebraska Medical Center, Omaha, NE, 68198, USA
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8
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Uzairue LI, Shittu OB, Ojo OE, Obuotor TM, Olanipekun G, Ajose T, Arogbonlo R, Medugu N, Ebruke B, Obaro SK. Antimicrobial resistance and virulence genes of invasive Salmonella enterica from children with bacteremia in north-central Nigeria. SAGE Open Med 2023; 11:20503121231175322. [PMID: 37223673 PMCID: PMC10201152 DOI: 10.1177/20503121231175322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 04/25/2023] [Indexed: 05/25/2023] Open
Abstract
Objectives Bacteremia due to invasive Salmonella enterica has been reported earlier in children in Nigeria. This study aimed to detect the virulence and antibiotic resistance genes of invasive Salmonella enterica from children with bacteremia in north-central Nigeria. Method From June 2015 to June 2018, 4163 blood cultures yielded 83 Salmonella isolates. This is a secondary cross-sectional analysis of the Salmonella isolates. The Salmonella enterica were isolated and identified using standard bacteriology protocol. Biochemical identifications of the Salmonella enterica were made by Phoenix MD 50 identification system. Further identification and confirmation were done with polyvalent antisera O and invA gene. Antimicrobial susceptibility testing was done following clinical and laboratory standard institute guidelines. Resistant genes and virulence genes were determined using a real-time polymerase chain reaction. Result Salmonella typhi 51 (61.4%) was the most prevalent serovar, followed by Salmonella species 13 (15.7%), choleraesuis 8 (9.6%), enteritidis 6 (7.2%), and typhimurium 5 (6.1%). Fifty-one (61.4%) of 83 Salmonella enterica were typhoidal, while 32 (38.6%) were not. Sixty-five (78.3%) of the 83 Salmonella enterica isolates were resistant to ampicillin and trimethoprim-sulfamethoxazole, followed by chloramphenicol 39 (46.7%), tetracycline 41 (41.4%), piperacillin 33 (33.9%), amoxicillin-clavulanate, and streptomycin 21 (25.3%), while cephalothin was 19 (22.9%). Thirty-nine (46.9%) of the 83 Salmonella enterica isolates were multi-drug resistant, and none were extensive drug resistant or pan-drug resistant. A blaTEM 42 (50.6%), floR 32 (38.6%), qnrA 24 (28.9%), tetB 20 (20.1%), tetA 10 (10.0%), and tetG 5 (6.0%) were the antibiotic resistance genes detected. There were perfect agreement between phenotypic and genotypic detection of antimicrobial resistance in tetracycline, ciprofloxacin, and chloramphenicol, while beta-lactam showed κ = 0.60 agreement. All of the Salmonella enterica isolates had the virulence genes invA, sopB, mgtC, and sip4D, while 33 (39.8%), 45 (51.8%), and 2 (2.4%) had ssaQ, spvC, and ljsGI-1, respectively. Conclusion Our findings showed multi-drug resistant Salmonella enterica in children with bacteremia in northern Nigeria. In addition, significant virulence and antimicrobial resistance genes were found in invasive Salmonella enterica in northern Nigeria. Thus, our study emphasizes the need to monitor antimicrobial resistance in Salmonella enterica from invasive sources in Nigeria and supports antibiotic prudence.
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Affiliation(s)
- Leonard I Uzairue
- Department of Microbiology, Federal
University of Agriculture, Abeokuta, Ogun State, Nigeria
- International Foundation Against
Infectious Disease in Nigeria, Abuja, Nigeria
- Department of Medical Laboratory
Sciences, Federal University Oye Ekiti, Ekiti State, Nigeria
| | - Olufunke B Shittu
- Department of Microbiology, Federal
University of Agriculture, Abeokuta, Ogun State, Nigeria
| | - Olufemi E Ojo
- Department of Veterinary Microbiology
and Parasitology, Federal University of Agriculture, Abeokuta, Nigeria
| | - Tolulope M Obuotor
- Department of Microbiology, Federal
University of Agriculture, Abeokuta, Ogun State, Nigeria
| | - Grace Olanipekun
- International Foundation Against
Infectious Disease in Nigeria, Abuja, Nigeria
| | - Theresa Ajose
- International Foundation Against
Infectious Disease in Nigeria, Abuja, Nigeria
| | - Ronke Arogbonlo
- International Foundation Against
Infectious Disease in Nigeria, Abuja, Nigeria
| | - Nubwa Medugu
- International Foundation Against
Infectious Disease in Nigeria, Abuja, Nigeria
- Department of Microbiology and
Parasitology, National Hospital, Abuja, FCT, Nigeria
| | - Bernard Ebruke
- International Foundation Against
Infectious Disease in Nigeria, Abuja, Nigeria
| | - Stephen K Obaro
- International Foundation Against
Infectious Disease in Nigeria, Abuja, Nigeria
- Pediatric Infectious Division, the
University of Nebraska Medical Center, Omaha, NE, USA
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Lo SW, Mellor K, Cohen R, Alonso AR, Belman S, Kumar N, Hawkins PA, Gladstone RA, von Gottberg A, Veeraraghavan B, Ravikumar KL, Kandasamy R, Pollard SAJ, Saha SK, Bigogo G, Antonio M, Kwambana-Adams B, Mirza S, Shakoor S, Nisar I, Cornick JE, Lehmann D, Ford RL, Sigauque B, Turner P, Moïsi J, Obaro SK, Dagan R, Diawara I, Skoczyńska A, Wang H, Carter PE, Klugman KP, Rodgers G, Breiman RF, McGee L, Bentley SD, Almagro CM, Varon E, Corso A, Davydov A, Maguire A, Kiran A, Moiane B, Beall B, Zhao C, Aanensen D, Everett D, Faccone D, Foster-Nyarko E, Bojang E, Egorova E, Voropaeva E, Sampane-Donkor E, Sadowy E, Nagaraj G, Mucavele H, Belabbès H, Elmdaghri N, Verani J, Keenan J, Lees J, N Nair Thulasee Bhai J, Ndlangisa K, Zerouali K, Bentley L, Titov L, De Gouveia L, Alaerts M, Ip M, de Cunto Brandileone MC, Hasanuzzaman M, Paragi M, Nurse-Lucas M, du Plessis M, Ali M, Croucher N, Wolter N, Givon-Lavi N, Porat N, Köseoglu Eser Ö, Ho PL, Eberechi Akpaka P, Gagetti P, Tientcheu PE, Law P, Benisty R, Mostowy R, Malaker R, Grassi Almeida SC, Doiphode S, Madhi S, Devi Sekaran S, Clarke S, Srifuengfung S, Nzenze S, Kastrin T, Ochoa T, Hryniewicz W, Urban Y. Emergence of a multidrug-resistant and virulent Streptococcus pneumoniae lineage mediates serotype replacement after PCV13: an international whole-genome sequencing study. Lancet Microbe 2022; 3:e735-e743. [PMID: 35985351 PMCID: PMC9519462 DOI: 10.1016/s2666-5247(22)00158-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 06/01/2022] [Accepted: 06/01/2022] [Indexed: 12/24/2022]
Abstract
BACKGROUND Serotype 24F is one of the emerging pneumococcal serotypes after the introduction of pneumococcal conjugate vaccine (PCV). We aimed to identify lineages driving the increase of serotype 24F in France and place these findings into a global context. METHODS Whole-genome sequencing was performed on a collection of serotype 24F pneumococci from asymptomatic colonisation (n=229) and invasive disease (n=190) isolates among individuals younger than 18 years in France, from 2003 to 2018. To provide a global context, we included an additional collection of 24F isolates in the Global Pneumococcal Sequencing (GPS) project database for analysis. A Global Pneumococcal Sequence Cluster (GPSC) and a clonal complex (CC) were assigned to each genome. Phylogenetic, evolutionary, and spatiotemporal analysis were conducted using the same 24F collection and supplemented with a global collection of genomes belonging to the lineage of interest from the GPS project database (n=25 590). FINDINGS Serotype 24F was identified in numerous countries mainly due to the clonal spread of three lineages: GPSC10 (CC230), GPSC16 (CC156), and GPSC206 (CC7701). GPSC10 was the only multidrug-resistant lineage. GPSC10 drove the increase in 24F in France and had high invasive disease potential. The international dataset of GPSC10 (n=888) revealed that this lineage expressed 16 other serotypes, with only six included in 13-valent PCV (PCV13). All serotype 24F isolates were clustered in a single clade within the GPSC10 phylogeny and long-range transmissions were detected from Europe to other continents. Spatiotemporal analysis showed GPSC10-24F took 3-5 years to spread across France and a rapid change of serotype composition from PCV13 serotype 19A to 24F during the introduction of PCV13 was observed in neighbouring country Spain. INTERPRETATION Our work reveals that GPSC10 alone is a challenge for serotype-based vaccine strategy. More systematic investigation to identify lineages like GPSC10 will better inform and improve next-generation preventive strategies against pneumococcal diseases. FUNDING Bill & Melinda Gates Foundation, Wellcome Sanger Institute, and the US Centers for Disease Control and Prevention.
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Affiliation(s)
- Stephanie W Lo
- Parasites and Microbes Programme, Wellcome Sanger Institute, Hinxton, UK,Correspondence to: Dr Stephanie W Lo, Parasites and Microbes Programme, Wellcome Sanger Institute, Hinxton, CB10 1SA, UK
| | - Kate Mellor
- Parasites and Microbes Programme, Wellcome Sanger Institute, Hinxton, UK
| | - Robert Cohen
- ACTIV, Association Clinique et Thérapeutique Infantile du Val-de-Marne, Saint Maur-des-Fossés, France,GPIP, Groupe de Pathologie Infectieuse Pédiatrique, Paris, France,AFPA, Association Française de Pédiatrie Ambulatoire, Saint-Germain-en-Laye, France,Université Paris Est, IMRB-GRC GEMINI, Créteil, France,Clinical Research Center, Centre Hospitalier Intercommunal de Créteil, Créteil, France,Unité Court Séjour, Petits nourrissons, Service de Néonatalogie, Centre Hospitalier Intercommunal de Créteil, Créteil, France
| | - Alba Redin Alonso
- Department of RDI Microbiology, Institut de Recerca Sant Joan de Deu, Hospital Sant Joan de Deu, Barcelona, Spain,School of Medicine, Universitat Internacional de Catalunya, Barcelona, Spain,Spanish Network of Epidemiology and Public Health, CIBERESP, Instituto de Salud Carlos III, Madrid, Spain
| | - Sophie Belman
- Parasites and Microbes Programme, Wellcome Sanger Institute, Hinxton, UK
| | - Narender Kumar
- Parasites and Microbes Programme, Wellcome Sanger Institute, Hinxton, UK
| | | | - Rebecca A Gladstone
- Department of Biostatistics, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Anne von Gottberg
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases, Johannesburg, South Africa
| | | | - K L Ravikumar
- Central Research Laboratory, Kempegowda Institute of Medical Sciences, Bangalore, India
| | - Rama Kandasamy
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Churchill Hospital, Oxford, UK,NIHR Oxford Biomedical Research Centre, Oxford, UK,School of Women and Children's Health, University of New South Wales, Sydney, NSW, Australia,Discipline of Paediatrics and Child Health, School of Clinical Medicine, University of New South Wales, Sydney, NSW, Australia
| | - Sir Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Churchill Hospital, Oxford, UK,NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Samir K Saha
- Child Health Research Foundation, Dhaka, Bangladesh
| | | | - Martin Antonio
- WHO Collaborating Centre for New Vaccines Surveillance, Medical Research Council Unit The Gambia at The London School of Hygiene & Tropical Medicine, Fajara, The Gambia
| | - Brenda Kwambana-Adams
- WHO Collaborating Centre for New Vaccines Surveillance, Medical Research Council Unit The Gambia at The London School of Hygiene & Tropical Medicine, Fajara, The Gambia,NIHR Global Health Research Unit on Mucosal Pathogens, Division of Infection and Immunity, University College London, London, UK
| | - Shaper Mirza
- Microbiology and Immunology Laboratory, Department of Biology, Lahore University of Management Sciences, Lahore, Pakistan
| | - Sadia Shakoor
- Department of Pediatrics and Child Health, Aga Khan University, Karachi, Pakistan
| | - Imran Nisar
- Department of Pediatrics and Child Health, Aga Khan University, Karachi, Pakistan
| | - Jennifer E Cornick
- Malawi-Liverpool-Wellcome-Trust, Blantyre, Malawi,Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Deborah Lehmann
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, The University of Western Australia, Perth, WA, Australia
| | - Rebecca L Ford
- Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea
| | - Betuel Sigauque
- Centro de Investigação em Saúde da Manhiça, Maputo, Mozambique
| | - Paul Turner
- Cambodia Oxford Medical Research Unit, Angkor Hospital for Children, Siem Reap, Cambodia,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | | | - Stephen K Obaro
- Division of Pediatric Infectious Disease, University of Nebraska Medical Center Omaha, Omaha, NE, USA,International Foundation against Infectious Diseases in Nigeria, Abuja, Nigeria
| | - Ron Dagan
- Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Idrissa Diawara
- Department of Microbiology, Faculty of Medicine and Pharmacy of Casablanca, Hassan II University of Casablanca, Casablanca, Morocco,National Reference Laboratory, Mohammed VI University of Health Sciences, Casablanca, Morocco
| | - Anna Skoczyńska
- Department of Epidemiology and Clinical Microbiology, National Medicines Institute, Warsaw, Poland
| | - Hui Wang
- Peking University People ‘s Hospital, Beijing, China
| | - Philip E Carter
- Institute of Environmental Science and Research Limited, Kenepuru Science Centre, Porirua, New Zealand
| | - Keith P Klugman
- Rollins School Public Health, Emory University, Atlanta, GA, USA
| | - Gail Rodgers
- Pneumonia Program, Bill & Melinda Gates Foundation, Seattle, WA, USA
| | - Robert F Breiman
- Rollins School Public Health, Emory University, Atlanta, GA, USA,Emory Global Health Institute, Emory University, Atlanta, GA, USA
| | - Lesley McGee
- Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Stephen D Bentley
- Parasites and Microbes Programme, Wellcome Sanger Institute, Hinxton, UK
| | - Carmen Muñoz Almagro
- Department of RDI Microbiology, Institut de Recerca Sant Joan de Deu, Hospital Sant Joan de Deu, Barcelona, Spain,School of Medicine, Universitat Internacional de Catalunya, Barcelona, Spain,Spanish Network of Epidemiology and Public Health, CIBERESP, Instituto de Salud Carlos III, Madrid, Spain
| | - Emmanuelle Varon
- National Reference Center for Pneumococci, Centre Hospitalier Intercommunal de Créteil, Créteil, France
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10
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Shittu OB, Uzairue LI, Ojo OE, Obuotor TM, Folorunso JB, Raheem-Ademola RR, Olanipekun G, Ajose T, Medugu N, Ebruke B, Obaro SK. Antimicrobial resistance and virulence genes in Salmonella enterica serovars isolated from droppings of layer chicken in two farms in Nigeria. J Appl Microbiol 2022; 132:3891-3906. [PMID: 35129256 DOI: 10.1111/jam.15477] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 01/26/2022] [Accepted: 02/03/2022] [Indexed: 11/28/2022]
Abstract
AIM This study aimed to investigate the isolation rate, antibiotic resistance, and virulence genes of Salmonella enterica serovar from two commercial farms in Nigeria. METHODS AND RESULTS Salmonella isolation was performed according to the United States Food and Drug Agency (USFDA) method. Serotyping, antimicrobial susceptibility testing, detection of resistance and virulence genes were done using the Kauffman-White Scheme, disc diffusion, minimum inhibitory concentration, and real-time polymerase chain reaction techniques. Salmonella serovars were isolated from only farm A at 22/50 (44.0%) while none were isolated from farm B. Salmonella Typhi, 9 (40.9%); Salmonella Typhimurium, 2 (9.1%), Salmonella Enteritidis, 2 (9.1%), Salmonella Pullorum, 1 (4.5%), Salmonella Kentucky, 4 (18.2%) were identified while 4 (18.2%) were untypable. Sixteen isolates (72.7%) showed multiple drug resistance and 17 different resistance profile types with AMP-CHL-TRM-SXT as the most prevalent pattern. Resistance genes (blaTEM, 12/22 (54.5%) and virulence genes (InvA, sopB, mgtC, and spi4D, 22/22 (100.0%), ssaQ, 16/22 (72.7%), and spvC, 13/22 (59.1%) were found, while blaSHV, blaCTX-M, floR, tetA, tetB, tetG, and LJSGI-1 genes were absent. CONCLUSION Pathogenic Salmonella were isolated from the chicken droppings in this study. Most of these strains were resistant to antibiotics and possessed characteristics of virulence. SIGNIFICANCE AND IMPACT OF THE STUDY Chicken droppings from this study area contained pathogenic strains of Salmonella and a rare occurrence of Salmonella Typhi. The study revealed that the environment and the food chain could be at risk of contamination of highly virulent and antimicrobial-resistant strains of Salmonella. These could affect the profitability of the poultry industry and food consumption. There is a need for caution in indiscriminate disposal of poultry waste and the use of uncomposted chicken droppings in soil amendment.
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Affiliation(s)
- Olufunke B Shittu
- Department of Microbiology, Federal University of Agriculture, Abeokuta, Ogun State, Nigeria
| | - Leonard I Uzairue
- Department of Microbiology, Federal University of Agriculture, Abeokuta, Ogun State, Nigeria.,International Foundation Against Infectious Disease in Nigeria(IFAIN), Abuja, Nigeria.,Department of Medical Laboratory Sciences, Federal University Oye Ekiti, Ekiti State, Nigeria
| | - Olufemi E Ojo
- Department of Veterinary Microbiology and Parasitology, Federal University of Agriculture, Abeokuta, Nigeria
| | - Tolulope M Obuotor
- Department of Microbiology, Federal University of Agriculture, Abeokuta, Ogun State, Nigeria
| | - Jamiu B Folorunso
- Department of Microbiology, Federal University of Agriculture, Abeokuta, Ogun State, Nigeria.,Department of Community Medicine, Olabisi Onabanjo Teaching Hospital, Nigeria
| | | | - Grace Olanipekun
- International Foundation Against Infectious Disease in Nigeria(IFAIN), Abuja, Nigeria
| | - Theresa Ajose
- International Foundation Against Infectious Disease in Nigeria(IFAIN), Abuja, Nigeria
| | - Nubwa Medugu
- International Foundation Against Infectious Disease in Nigeria(IFAIN), Abuja, Nigeria.,Department of Microbiology and Parasitology, National Hospital, Abuja, Nigeria
| | - Bernard Ebruke
- International Foundation Against Infectious Disease in Nigeria(IFAIN), Abuja, Nigeria
| | - Stephen K Obaro
- International Foundation Against Infectious Disease in Nigeria(IFAIN), Abuja, Nigeria.,Pediatric Infectious Division, University of Nebraska Medical Center, Omaha, USA
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11
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Ogunkunle TO, Adedoyin TO, Ernest SK, Hassan-Hanga F, Imam A, Olaosebikan R, Obaro SK. A Prospective Cohort Study of the Clinical Predictors of Bacteremia in Under-Five Children With Acute Undifferentiated Fever Attending a Secondary Health Facility in Northwestern Nigeria. Front Pediatr 2021; 9:730082. [PMID: 35242726 PMCID: PMC8885983 DOI: 10.3389/fped.2021.730082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 12/27/2021] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Children with acute febrile illness with no localizing signs often receive antibiotics empirically in most resource-poor settings. However, little is known about the burden of bacteremia in this category of patients, and an appraisal is thus warranted. This will guide clinical practice and promote rational antibiotics use. METHODS We prospectively followed up 140 under-five children who presented with acute undifferentiated fever at the emergency/outpatient pediatric unit of a secondary healthcare facility. Baseline clinical and laboratory information was obtained and documented in a structured questionnaire. We compared baseline characteristics between participants with bacteremia and those without bacteremia. We further fitted a multivariable logistic regression model to identify factors predictive of bacteremia among the cohort. RESULT The prevalence of bacteremia was 17.1%, and Salmonella Typhi was the most frequently (40.9%) isolated pathogen. The majority (78.6%) of the study participants were managed as outpatients. The participants who required admission were four times more likely to have bacteremia when compared to those managed as outpatients (AOR 4.08, 95% CI 1.19 to 14.00). There is a four times likelihood of bacteremia (AOR 4.75, 95% CI 1.48 to 15.29) with a fever duration of beyond 7 days. Similarly, participants who were admitted with lethargy were six times more likely to have bacteremia (AOR 6.20, 95% CI 1.15 to 33.44). Other significant predictors were tachypnea and lymphopenia. CONCLUSION Among under-five children with acute undifferentiated fever, longer duration of fever, lethargy, inpatient care, tachypnea, and lymphopenia were the significant predictors of bacteremia.
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Affiliation(s)
| | - Timothy Olanrewaju Adedoyin
- Department of Paediatrics and Child Health, University of Ilorin/University of Ilorin Teaching Hospital, Ilorin, Nigeria
| | - Samuel Kolade Ernest
- Department of Paediatrics and Child Health, University of Ilorin/University of Ilorin Teaching Hospital, Ilorin, Nigeria
| | - Fatimah Hassan-Hanga
- Department of Paediatrics and Child Health, Aminu Kano University Teaching Hospital, Kano, Nigeria
| | - Abdulazeez Imam
- Oxford Centre for Global Health Research, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Rasaq Olaosebikan
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA, United States
| | - Stephen K Obaro
- Division of Pediatric Infectious Diseases, Department of Pediatrics/Department of Microbiology and Pathology, University of Nebraska Medical Center, Omaha, NE, United States
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12
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Chaguza C, Yang M, Cornick JE, du Plessis M, Gladstone RA, Kwambana-Adams BA, Lo SW, Ebruke C, Tonkin-Hill G, Peno C, Senghore M, Obaro SK, Ousmane S, Pluschke G, Collard JM, Sigaùque B, French N, Klugman KP, Heyderman RS, McGee L, Antonio M, Breiman RF, von Gottberg A, Everett DB, Kadioglu A, Bentley SD. Bacterial genome-wide association study of hyper-virulent pneumococcal serotype 1 identifies genetic variation associated with neurotropism. Commun Biol 2020; 3:559. [PMID: 33033372 PMCID: PMC7545184 DOI: 10.1038/s42003-020-01290-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 09/11/2020] [Indexed: 12/19/2022] Open
Abstract
Hyper-virulent Streptococcus pneumoniae serotype 1 strains are endemic in Sub-Saharan Africa and frequently cause lethal meningitis outbreaks. It remains unknown whether genetic variation in serotype 1 strains modulates tropism into cerebrospinal fluid to cause central nervous system (CNS) infections, particularly meningitis. Here, we address this question through a large-scale linear mixed model genome-wide association study of 909 African pneumococcal serotype 1 isolates collected from CNS and non-CNS human samples. By controlling for host age, geography, and strain population structure, we identify genome-wide statistically significant genotype-phenotype associations in surface-exposed choline-binding (P = 5.00 × 10-08) and helicase proteins (P = 1.32 × 10-06) important for invasion, immune evasion and pneumococcal tropism to CNS. The small effect sizes and negligible heritability indicated that causation of CNS infection requires multiple genetic and other factors reflecting a complex and polygenic aetiology. Our findings suggest that certain pathogen genetic variation modulate pneumococcal survival and tropism to CNS tissue, and therefore, virulence for meningitis.
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Affiliation(s)
- Chrispin Chaguza
- Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, UK.
- Darwin College, University of Cambridge, Silver Street, Cambridge, UK.
| | - Marie Yang
- Department of Clinical Infection, Microbiology and Immunology, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Jennifer E Cornick
- Department of Clinical Infection, Microbiology and Immunology, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | - Mignon du Plessis
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases, Johannesburg, South Africa
- School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Rebecca A Gladstone
- Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, UK
| | - Brenda A Kwambana-Adams
- NIHR Global Health Research Unit on Mucosal Pathogens, Division of Infection and Immunity, University College London, London, UK
- Medical Research Council (MRC) Unit The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Stephanie W Lo
- Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, UK
| | - Chinelo Ebruke
- Medical Research Council (MRC) Unit The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Gerry Tonkin-Hill
- Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, UK
| | - Chikondi Peno
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- MRC Centre for Inflammation Research, Queens Medical Research Institute, University of Edinburgh, Edinburgh, UK
| | - Madikay Senghore
- Medical Research Council (MRC) Unit The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard TH Chan School of Public Health, Boston, MA, USA
| | - Stephen K Obaro
- Division of Pediatric Infectious Disease, University of Nebraska Medical Center Omaha, Omaha, NE, USA
- International Foundation against Infectious Diseases in Nigeria, Abuja, Nigeria
| | - Sani Ousmane
- Centre de Recherche Médicale et Sanitaire, Niamey, Niger
| | - Gerd Pluschke
- Swiss Tropical and Public Health Institute, Basel, Switzerland
| | | | - Betuel Sigaùque
- Centro de Investigação em Saúde da Manhiça, Maputo, Mozambique
| | - Neil French
- Department of Clinical Infection, Microbiology and Immunology, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Keith P Klugman
- Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA
| | - Robert S Heyderman
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- NIHR Global Health Research Unit on Mucosal Pathogens, Division of Infection and Immunity, University College London, London, UK
| | - Lesley McGee
- Respiratory Diseases Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Martin Antonio
- Medical Research Council (MRC) Unit The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
- Warwick Medical School, University of Warwick, Coventry, UK
| | - Robert F Breiman
- Emory Global Health Institute, Emory University, Atlanta, GA, USA
| | - Anne von Gottberg
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases, Johannesburg, South Africa
- School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Dean B Everett
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- MRC Centre for Inflammation Research, Queens Medical Research Institute, University of Edinburgh, Edinburgh, UK
| | - Aras Kadioglu
- Department of Clinical Infection, Microbiology and Immunology, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Stephen D Bentley
- Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, UK.
- Department of Pathology, University of Cambridge, Cambridge, UK.
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13
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Peter ID, Asani MO, Abdullahi SU, Aliyu I, Obaro SK, Bode-Thomas F. Pulmonary hypertension and right ventricular function in Nigerian children with sickle cell anaemia. Trans R Soc Trop Med Hyg 2020; 113:489-496. [PMID: 31086994 PMCID: PMC6677931 DOI: 10.1093/trstmh/trz038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 04/02/2019] [Indexed: 01/28/2023] Open
Abstract
Background Pulmonary hypertension (PH), a complication of sickle cell anaemia (SCA), results in considerable morbidity. This study aims to determine the prevalence and associations of echocardiography-suggested PH in children with SCA. Methods We performed a cross-sectional comparative study involving 100 systematically sampled SCA subjects 3–14 y of age in their steady state with matched haemoglobin AA phenotype controls. Clinical, laboratory and echocardiography data (including tricuspid regurgitation velocity [TRV], mean pulmonary arterial pressure [mPAP] and tricuspid annular plane systolic excursion [TAPSE]) were obtained from all patients. Statistical analyses were performed using SPSS version 22 (IBM, Armonk, NY, USA). A p-value <0.05 was considered statistically significant. Results Of the 100 SCA subjects studied, 22 (22%) had echocardiographic findings suggestive of PH compared with none in the controls. The median TAPSE was significantly lower in the PH group (2.55 cm [interquartile range {IQR} 2.2–2.8]) compared with the no PH group (2.77 cm [IQR 2.4–3.2]) (p=0.03). No significant correlation existed between mPAP and age, nor any laboratory parameters studied. The odds ratio (OR) suggested PH significantly increased with an increase in the frequency of hospitalizations for vaso-occlusive crises within a 12-month period (OR 15.15 [95% CI 1.57 to 146.35], p=0.02) and a lifetime history of blood transfusion (OR 5.44 [95% CI 1.09 to 27.24], p=0.04). Conclusions Echocardiography-suggested PH is common in children with SCA and is associated with poorer right ventricular function, frequent vaso-occlusive crises and blood transfusions.
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Affiliation(s)
- Igoche D Peter
- Department of Paediatrics, Aminu Kano Teaching Hospital, Kano, Nigeria
| | - Mustafa O Asani
- Department of Paediatrics, Bayero University Kano/Aminu Kano Teaching Hospital, Kano, Nigeria
| | - Shehu U Abdullahi
- Department of Paediatrics, Bayero University Kano/Aminu Kano Teaching Hospital, Kano, Nigeria
| | - Ibrahim Aliyu
- Department of Paediatrics, Bayero University Kano/Aminu Kano Teaching Hospital, Kano, Nigeria
| | - Stephen K Obaro
- Department of Paediatrics, Aminu Kano Teaching Hospital, Kano, Nigeria.,Department of Paediatrics, University of Nebraska Medical Centre, Omaha, NE, USA.,International Foundation Against Infectious Diseases in Nigeria, Abuja, Nigeria
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14
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Hasan MN, Fraiwan A, An R, Alapan Y, Ung R, Akkus A, Xu JZ, Rezac AJ, Kocmich NJ, Creary MS, Oginni T, Olanipekun GM, Hassan-Hanga F, Jibir BW, Gambo S, Verma AK, Bharti PK, Riolueang S, Ngimhung T, Suksangpleng T, Thota P, Werner G, Shanmugam R, Das A, Viprakasit V, Piccone CM, Little JA, Obaro SK, Gurkan UA. Paper-based microchip electrophoresis for point-of-care hemoglobin testing. Analyst 2020; 145:2525-2542. [PMID: 32123889 DOI: 10.1039/c9an02250c] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Nearly 7% of the world's population live with a hemoglobin variant. Hemoglobins S, C, and E are the most common and significant hemoglobin variants worldwide. Sickle cell disease, caused by hemoglobin S, is highly prevalent in sub-Saharan Africa and in tribal populations of Central India. Hemoglobin C is common in West Africa, and hemoglobin E is common in Southeast Asia. Screening for significant hemoglobin disorders is not currently feasible in many low-income countries with the high disease burden. Lack of early diagnosis leads to preventable high morbidity and mortality in children born with hemoglobin variants in low-resource settings. Here, we describe HemeChip, the first miniaturized, paper-based, microchip electrophoresis platform for identifying the most common hemoglobin variants easily and affordably at the point-of-care in low-resource settings. HemeChip test works with a drop of blood. HemeChip system guides the user step-by-step through the test procedure with animated on-screen instructions. Hemoglobin identification and quantification is automatically performed, and hemoglobin types and percentages are displayed in an easily understandable, objective way. We show the feasibility and high accuracy of HemeChip via testing 768 subjects by clinical sites in the United States, Central India, sub-Saharan Africa, and Southeast Asia. Validation studies include hemoglobin E testing in Bangkok, Thailand, and hemoglobin S testing in Chhattisgarh, India, and in Kano, Nigeria, where the sickle cell disease burden is the highest in the world. Tests were performed by local users, including healthcare workers and clinical laboratory personnel. Study design, methods, and results are presented according to the Standards for Reporting Diagnostic Accuracy (STARD). HemeChip correctly identified all subjects with hemoglobin S, C, and E variants with 100% sensitivity, and displayed an overall diagnostic accuracy of 98.4% in comparison to reference standard methods. HemeChip is a versatile, mass-producible microchip electrophoresis platform that addresses a major unmet need of decentralized hemoglobin analysis in resource-limited settings.
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Affiliation(s)
- Muhammad Noman Hasan
- Case Biomanufacturing and Microfabrication Laboratory, Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA.
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15
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Brinkac LM, White R, D'Souza R, Nguyen K, Obaro SK, Fouts DE. Emergence of New Delhi Metallo-β-Lactamase (NDM-5) in Klebsiella quasipneumoniae from Neonates in a Nigerian Hospital. mSphere 2019; 4:e00685-18. [PMID: 30867330 PMCID: PMC6416368 DOI: 10.1128/msphere.00685-18] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 02/25/2019] [Indexed: 01/08/2023] Open
Abstract
Outbreaks of infection occur more often than they are reported in most developing countries, largely due to poor diagnostic services. A Klebsiella species bacteremia outbreak in a newborn unit with high mortality was recently encountered at a location being surveilled for childhood bacteremia. These surveillance efforts offered the opportunity to determine the cause of this neonatal outbreak. In this report, we present the whole-genome sequences of New Delhi metallo-β-lactamase (NDM-5)-containing Klebsiella quasipneumoniae subsp. similipneumoniae bloodstream isolates from a neonatal bacteremia outbreak at a tertiary hospital in Nigeria and as part of the largest collection of K. pneumoniae bloodstream isolates from children in Africa. Comparative analysis of the genetic environment surrounding the NDM-5 genes revealed nearly perfect sequence identity to blaNDM-5-bearing IncX3-type plasmids from other members of the EnterobacteriaceaeIMPORTANCE Carbapenem-resistant Klebsiella pneumoniae is of global health importance, yet there is a paucity of genome-based studies in Africa. Here we report fatal blood-borne NDM-5-producing K. quasipneumoniae subsp. similipneumoniae infections from Nigeria, Africa. New Delhi metallo-β-lactamase (NDM)-producing Klebsiella spp. are responsible for high mortality and morbidity, with the NDM-5 variant showing elevated carbapenem resistance. The prevalence of NDM-5 in Klebsiella has been limited primarily to K. pneumoniae, with only one isolate being collected from Africa. During an outbreak of sepsis in a teaching hospital in Nigeria, five NDM-5-producing K. quasipneumoniae subsp. similipneumoniae sequence type 476 isolates were identified. Given the increased resistance profile of these strains, this study highlights the emerging threat of blaNDM-5 dissemination in hospital environments. The observation of these NDM-5-producing isolates in Africa stresses the urgency to improve monitoring and clinical practices to reduce or prevent the further spread of resistance.
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Affiliation(s)
| | | | | | - Kevin Nguyen
- J. Craig Venter Institute, Rockville, Maryland, USA
| | - Stephen K Obaro
- University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Pediatrics, University of Abuja Teaching Hospital, Abuja, Nigeria
- International Foundation against Infectious Diseases in Nigeria (IFAIN), Abuja, Nigeria
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16
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Iroh Tam PY, Hernandez-Alvarado N, Schleiss MR, Yi AJ, Hassan-Hanga F, Onuchukwu C, Umoru D, Obaro SK. Detection of Streptococcus pneumoniae from culture-negative dried blood spots by real-time PCR in Nigerian children with acute febrile illness. BMC Res Notes 2018; 11:657. [PMID: 30201041 PMCID: PMC6131910 DOI: 10.1186/s13104-018-3770-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 09/07/2018] [Indexed: 11/25/2022] Open
Abstract
Objectives Acute febrile illness is a common cause of hospital admission, and its associated infectious causes, of which a key bacterial causative agent is Streptococcus pneumoniae, contribute to substantial morbidity and mortality. We sought to evaluate the utility of real-time (rt)-PCR on dried blood spots (DBS) for diagnosis of S. pneumoniae in acute febrile illness among children presenting to hospitals in Nigeria. We previously described preliminary results in a sample of 537 patients. Here we present data from a larger collection of 1038 patients. Results Using rt-PCR for Streptococcus pneumoniae on 1038 dried blood spots from children prospectively enrolled with acute febrile illness, including 79 healthy controls, we detected pneumococcal DNA in nine of 15 blood culture-positive specimens, one culture-negative specimen from a high-risk group, a culture-confirmed non-pneumococcal specimen and a healthy control. Six culture-positive isolates (40%) were negative. Sensitivity was 60%, specificity 99.7%, positive predictive value 75% and negative predictive value 99.4%. Rt-PCR of DBS has limited sensitivity in blood specimens from acute febrile illness in children.
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Affiliation(s)
- Pui-Ying Iroh Tam
- Division of Pediatric Infectious Diseases and Immunology, University of Minnesota, Minneapolis, MN, USA. .,Malawi-Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi. .,Liverpool School of Tropical Medicine, Liverpool, UK.
| | | | - Mark R Schleiss
- Division of Pediatric Infectious Diseases and Immunology, University of Minnesota, Minneapolis, MN, USA
| | - Amy J Yi
- Division of Pediatric Infectious Diseases and Immunology, University of Minnesota, Minneapolis, MN, USA
| | | | | | | | - Stephen K Obaro
- Aminu Kano Teaching Hospital, Kano, Nigeria.,University of Nebraska Medical Center, Omaha, NE, USA.,International Foundation Against Infectious Diseases in Nigeria, Abuja, Nigeria.,University of Abuja Teaching Hospital, Gwagwalada, Nigeria
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17
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Lim SH, Methé BA, Knoll BM, Morris A, Obaro SK. Invasive non-typhoidal Salmonella in sickle cell disease in Africa: is increased gut permeability the missing link? J Transl Med 2018; 16:239. [PMID: 30165857 PMCID: PMC6116559 DOI: 10.1186/s12967-018-1622-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 08/25/2018] [Indexed: 02/07/2023] Open
Abstract
Non-typhoidal Salmonella usually induces self-limiting gastroenteritis. However, in many parts of Africa, especially in individuals who are malnourished, infected with malaria, or have sickle cell disease, the organism causes serious and potentially fatal systemic infections. Since the portal of entry of non-typhoidal Salmonella into the systemic circulation is by way of the intestine, we argue that an increased gut permeability plays a vital role in the initiation of invasive non-typhoidal Salmonella in these patients. Here, we will appraise the evidence supporting a breach in the intestinal barrier and propose the mechanisms for the increased risks for invasive non-typhoidal Salmonella infections in these individuals.
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Affiliation(s)
- Seah H Lim
- Division of Hematology and Oncology, New York Medical College, Hawthorne, NY, USA. .,Westchester Medical Center Cancer Institute, 19 Bradhurst Avenue, Suite 2575S, Hawthorne, NY, 10532, USA.
| | - Barbara A Methé
- Center for Microbiome in Medicine, University of Pittsburgh School of Medicine, Pittsburgh, USA
| | - Bettina M Knoll
- Division of Infectious Diseases, New York Medical College, Hawthorne, NY, USA
| | - Alison Morris
- Center for Microbiome in Medicine, University of Pittsburgh School of Medicine, Pittsburgh, USA
| | - Stephen K Obaro
- Department of Pediatrics, University of Nebraska Medical Center, Omaha, NE, USA
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18
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Abstract
Typhoid fever continues to pose a serious health challenge in developing countries. A reliable database on positive blood cultures is essential for prompt interventions. To generate reliable data on Salmonella enterica serovar Typhi (S. Typhi)–positive blood culture trends in typhoidal Salmonella in Nigeria alongside changing contextual factors and antimicrobial resistance patterns, a retrospective cohort study was conducted in two hospitals in Lagos between 1993 and 2015. Medical records of typhoid patients were reviewed for positive culture and antibiogram, using standard procedures and analyzed. Additional data were retrieved from a previous study in seven facilities in Abuja and three hospitals in Kano from 2008 to 2017 and 2013 to 2017, respectively. A declining trend in percent positivity of S. Typhi was observed in Abuja with more erratic trends in Lagos and Kano. In Lagos, more than 80% of the isolates from the entire study period exhibited multiple drug resistance with a generally increasing trend. Of the chosen contextual factors, improvements were recorded in female literacy, access to improved water supply, diarrheal mortality in children younger than 5 years, gross domestic product, and poverty while access to improved sanitation facilities decreased over time nationally. Typhoid fever still poses a serious health challenge in Nigeria and in antibiotic resistance, and is a major health security issue. A combined approach that includes the use of typhoid vaccines, improvements in sanitation, and safe water supply is essential.
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Affiliation(s)
| | | | - Wasiu Bamidele Mutiu
- Department of Medical Microbiology and Parasitology, College of Medicine, Lagos State University, Lagos, Nigeria
| | - Bamidele Abiodun Iwalokun
- Biochemistry Unit and Malaria Research Laboratory, Nigerian Institute of Medical Research, Lagos, Nigeria
| | | | | | - Stephen K Obaro
- International Foundation Against Infectious Diseases in Nigeria (IFAIN), Abuja, Nigeria.,Division of Pediatric Infectious Disease, University of Nebraska Medical Centre, Omaha, Nebraska
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19
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Obaro SK. Surveillance in Africa's meningitis belt: time for new targets? Lancet Glob Health 2018; 4:e514-5. [PMID: 27443772 DOI: 10.1016/s2214-109x(16)30095-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 05/06/2016] [Indexed: 10/21/2022]
Affiliation(s)
- Stephen K Obaro
- Division of Pediatric Infectious Diseases, University of Nebraska Medical Center 982165, Nebraska Medical Center, Omaha, NE 68198, USA; International Foundation Against Infectious Disease in Nigeria, Central Business Area, Abuja, Nigeria; University of Abuja Teaching Hospital, Abuja, Nigeria.
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20
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Abstract
BACKGROUND Pneumonia causes an enormous burden of childhood disease globally, particularly in low- and middle-income countries. Pneumococcus is the most common bacterial aetiology of pneumonia; however, antimicrobials are limited and may not adequately address the local epidemiology of the region. AIM To undertake a review and meta-analysis of pneumonia studies in sub-Saharan Africa to evaluate antimicrobial susceptibility patterns in childhood pneumonia. METHODS Articles published in PubMed and Google between 2006 and 2016 which evaluated antimicrobial susceptibility profiles of pneumococcal pneumonia in children in sub-Saharan Africa were identified. The source of specimens, pathogens and antimicrobial susceptibility data were extracted. Pooled analysis of susceptible isolates was conducted using random effects models. RESULTS Children from 15 studies and 1634 isolates were included in the meta-analysis. In cases of childhood pneumonia, the mean overall proportion of penicillin susceptibility from invasive specimens of Streptococcus pneumoniae was 85.7% (95% CI 80.1-91.3), and of trimethoprim-sulfamethoxazole was 21.0% (95% CI 5.1-36.9). Compared with all S. pneumoniae specimens, penicillin susceptibility was 68.6% (95% CI 59.6-77.5) and that of trimethoprim-sulfamethoxazole was 26.3% (95% CI 14.1-38.6). CONCLUSIONS A high level of heterogeneity was detected, reflecting the paucity of data available. The establishment of national and regional diagnostic platforms to monitor antimicrobial susceptibility profiles for pneumonia as well as other invasive diseases will provide data with which to assess the relevance and adaptation of antimicrobial prescribing recommendations.
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Affiliation(s)
- Pui-Ying Iroh Tam
- a Department of Pediatrics , University of Minnesota , Minneapolis , MN , USA
| | - Ayebo E Sadoh
- b Department of Pediatrics , University of Nebraska , Omaha , NE , USA
| | - Stephen K Obaro
- b Department of Pediatrics , University of Nebraska , Omaha , NE , USA
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21
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Abstract
INTRODUCTION Typhoid fever (TF), caused by Salmonella enterica serovar Typhi, is the most common cause of enteric fever, responsible for an estimated 129,000 deaths and more than 11 million cases annually. Although several reviews have provided global and regional TF disease burden estimates, major gaps in our understanding of TF epidemiology remain. Areas covered: We provide an overview of the gaps in current estimates of TF disease burden and offer suggestions for addressing them, so that affected communities can receive the full potential of disease prevention offered by vaccination and water, sanitation, and hygiene interventions. Expert commentary: Current disease burden estimates for TF do not capture cases from certain host populations, nor those with atypical presentations of TF, which may lead to substantial underestimation of TF cases and deaths. These knowledge gaps pose major obstacles to the informed use of current and new generation typhoid vaccines.
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Affiliation(s)
- Stephen K Obaro
- a Department of Pediatrics , University of Nebraska Medical Center , Omaha , NE , USA
| | - Pui-Ying Iroh Tam
- b Department of Pediatrics , University of Minnesota Masonic Children's Hospital , Minneapolis , MN , USA
| | - Eric Daniel Mintz
- c Division of Foodborne, Waterborne and Environmental Diseases , Centers for Disease Control and Prevention , Atlanta , GA , USA
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22
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Obaro SK, Hassan-Hanga F, Olateju EK, Umoru D, Lawson L, Olanipekun G, Ibrahim S, Munir H, Ihesiolor G, Maduekwe A, Ohiaeri C, Adetola A, Shetima D, Jibir BW, Nakaura H, Kocmich N, Ajose T, Idiong D, Masokano K, Ifabiyi A, Ihebuzor N, Chen B, Meza J, Akindele A, Rezac-Elgohary A, Olaosebikan R, Suwaid S, Gambo M, Alter R, Davies HD, Fey PD. Salmonella Bacteremia Among Children in Central and Northwest Nigeria, 2008-2015. Clin Infect Dis 2016; 61 Suppl 4:S325-31. [PMID: 26449948 DOI: 10.1093/cid/civ745] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Etiologic agents of childhood bacteremia remain poorly defined in Nigeria. The absence of such data promotes indiscriminate use of antibiotics and delays implementation of appropriate preventive strategies. METHODS We established diagnostic laboratories for bacteremia surveillance at regional sites in central and northwest Nigeria. Acutely ill children aged <5 years with clinically suspected bacteremia were evaluated at rural and urban clinical facilities in the Federal Capital Territory, central region and in Kano, northwest Nigeria. Blood was cultured using the automated Bactec incubator system. RESULTS Between September 2008 and April 2015, we screened 10,133 children. Clinically significant bacteremia was detected in 609 of 4051 (15%) in the northwest and 457 of 6082 (7.5%) in the central region. Across both regions, Salmonella species account for 24%-59.8% of bacteremias and are the commonest cause of childhood bacteremia, with a predominance of Salmonella enterica serovar Typhi. The prevalence of resistance to ampicillin, chloramphenicol, and cotrimoxazole was 38.11%, with regional differences in susceptibility to different antibiotics but high prevalence of resistance to readily available oral antibiotics. CONCLUSIONS Salmonella Typhi is the leading cause of childhood bacteremia in central Nigeria. Expanded surveillance is planned to define the dynamics of transmission. The high prevalence of multidrug-resistant strains calls for improvement in environmental sanitation in the long term and vaccination in the short term.
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Affiliation(s)
- Stephen K Obaro
- Division of Pediatric Infectious Diseases Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha International Foundation Against Infectious Diseases in Nigeria, Abuja Department of Pediatrics Department of Pediatrics, University of Abuja Teaching Hospital, Gwagwalada
| | | | - Eyinade K Olateju
- Department of Pediatrics, University of Abuja Teaching Hospital, Gwagwalada
| | | | | | - Grace Olanipekun
- International Foundation Against Infectious Diseases in Nigeria, Abuja
| | - Sadeeq Ibrahim
- Department of Pediatrics Department of Medical Microbiology, Aminu Kano Teaching Hospital
| | - Huda Munir
- Department of Medical Microbiology, Aminu Kano Teaching Hospital
| | | | - Augustine Maduekwe
- Department of Pediatrics, Wuse General Hospital, Abuja, Federal Capital Territory
| | - Chinatu Ohiaeri
- Department of Pediatrics, Federal Medical Center, Keffi, Nassarawa State
| | | | - Denis Shetima
- Department of Pediatrics, National Hospital, Central Business Area, Abuja, Federal Capital Territory
| | - Binta W Jibir
- Department of Pediatrics, Murtala Specialist Hospital
| | | | | | - Therasa Ajose
- International Foundation Against Infectious Diseases in Nigeria, Abuja
| | - David Idiong
- International Foundation Against Infectious Diseases in Nigeria, Abuja Department of Microbiology, Bingham University, Karu, Nassarawa State
| | | | - Adeyemi Ifabiyi
- International Foundation Against Infectious Diseases in Nigeria, Abuja
| | - Nnenna Ihebuzor
- National Primary Health Care Development Agency, Abuja, Federal Capital Territory, Nigeria
| | - Baojiang Chen
- Department of Biostatistics, College of Public Health
| | - Jane Meza
- Department of Biostatistics, College of Public Health
| | - Adebayo Akindele
- International Foundation Against Infectious Diseases in Nigeria, Abuja
| | | | | | - Salman Suwaid
- Department of Pediatrics, Murtala Specialist Hospital
| | | | - Roxanne Alter
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha
| | - Herbert D Davies
- Division of Pediatric Infectious Diseases Department of Biostatistics, College of Public Health Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha
| | - Paul D Fey
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha
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23
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Iroh Tam PY, Obaro SK, Storch G. Challenges in the Etiology and Diagnosis of Acute Febrile Illness in Children in Low- and Middle-Income Countries. J Pediatric Infect Dis Soc 2016; 5:190-205. [PMID: 27059657 PMCID: PMC7107506 DOI: 10.1093/jpids/piw016] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 03/04/2016] [Indexed: 01/01/2023]
Abstract
Acute febrile illness is a common cause of hospital admission, and its associated infectious causes contribute to substantial morbidity and death among children worldwide, especially in low- and middle-income countries. Declining transmission of malaria in many regions, combined with the increasing use of rapid diagnostic tests for malaria, has led to the increasing recognition of leptospirosis, rickettsioses, respiratory viruses, and arboviruses as etiologic agents of fevers. However, clinical discrimination between these etiologies can be difficult. Overtreatment with antimalarial drugs is common, even in the setting of a negative test result, as is overtreatment with empiric antibacterial drugs. Viral etiologies remain underrecognized and poorly investigated. More-sensitive diagnostics have led to additional dilemmas in discriminating whether a positive test result reflects a causative pathogen. Here, we review and summarize the current epidemiology and focus particularly on children and the challenges for future research.
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Affiliation(s)
- Pui-Ying Iroh Tam
- Department of Pediatrics
,
University of Minnesota Medical School
,
Minneapolis,Corresponding Author:
Pui-Ying Iroh Tam, MD, 3-210 MTRF, 2001 6th St. SE, Minneapolis, MN 55455. E-mail:
| | - Stephen K. Obaro
- Department of Pediatrics, University of Nebraska Medical Center, Omaha
| | - Gregory Storch
- Department of Pediatrics
,
Washington University School of Medicine
,
St Louis, Missouri
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24
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Davies DH, Jain A, Nakajima R, Liang L, Jasinskis A, Supnet M, Felgner PL, Teng A, Pablo J, Molina DM, Obaro SK. Serodiagnosis of Acute Typhoid Fever in Nigerian Pediatric Cases by Detection of Serum IgA and IgG Against Hemolysin E and Lipopolysaccharide. Am J Trop Med Hyg 2016; 95:431-9. [PMID: 27215295 DOI: 10.4269/ajtmh.15-0869] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 04/04/2016] [Indexed: 01/03/2023] Open
Abstract
Inexpensive, easy-to-use, and highly sensitive diagnostic tests are currently unavailable for typhoid fever. To identify candidate serodiagnostic markers, we have probed microarrays displaying the full Salmonella enterica serovar Typhi (S. Typhi) proteome of 4,352 different proteins + lipopolysaccharides (LPSs), with sera from Nigerian pediatric typhoid and other febrile cases, Nigerian healthy controls, and healthy U.S. adults. Nigerian antibody profiles were broad (∼500 seropositive antigens) and mainly low level, with a small number of stronger "hits," whereas the profile in U.S. adults was < 1/5 as broad, consistent with endemic exposure in Nigeria. Nigerian profiles were largely unaffected by clinical diagnosis, although the response against t1477 (hemolysin E) consistently emerged as stronger in typhoid cases. The response to LPS was also a strong discriminator of healthy controls and typhoid, although LPS did not discriminate between typhoid and nontyphoidal Salmonella (NTS) disease. As a first step toward the development of a point-of-care diagnostic, t1477 and LPS were evaluated on immunostrips. Both provided good discrimination between healthy controls and typhoid/NTS disease. Such a test could provide a useful screen for salmonellosis (typhoid and NTS disease) in suspected pediatric cases that present with undefined febrile disease.
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Affiliation(s)
- D Huw Davies
- Division of Infectious Diseases, School of Medicine, University of California Irvine, California.
| | - Aarti Jain
- Division of Infectious Diseases, School of Medicine, University of California Irvine, California
| | - Rie Nakajima
- Division of Infectious Diseases, School of Medicine, University of California Irvine, California
| | - Li Liang
- Division of Infectious Diseases, School of Medicine, University of California Irvine, California
| | - Algis Jasinskis
- Division of Infectious Diseases, School of Medicine, University of California Irvine, California
| | - Medalyn Supnet
- Division of Infectious Diseases, School of Medicine, University of California Irvine, California
| | - Philip L Felgner
- Division of Infectious Diseases, School of Medicine, University of California Irvine, California
| | - Andy Teng
- Antigen Discovery, Inc., Irvine, California
| | | | | | - Stephen K Obaro
- Department of Pediatrics, University of Nebraska Medical Center, Omaha, Nebraska. International Foundation Against Infectious Diseases in Nigeria, Abuja, Nigeria. Aminu Kano Teaching Hospital, Kano, Nigeria. University of Abuja Teaching Hospital, Gwagwalada, Nigeria
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25
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Obaro SK, Iroh Tam PY. Preventing Infections in Sickle Cell Disease: The Unfinished Business. Pediatr Blood Cancer 2016; 63:781-5. [PMID: 26840500 DOI: 10.1002/pbc.25911] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 12/26/2015] [Accepted: 12/28/2015] [Indexed: 11/08/2022]
Abstract
While encapsulated bacterial agents, particularly Streptococcus pneumoniae, are recognized as important microbes that are associated with serious illness in hosts with sickle cell disease (SCD), multiple pathogens are implicated in infectious manifestations of SCD. Variations in clinical practice have been an obstacle to the universal implementation of infection preventive management through active, targeted vaccination of these individuals and routine usage of antibiotic prophylaxis. Paradoxically, in low-income settings, there is evidence that SCD also increases the risk for several other infections that warrant additional infection preventive measures. The infection preventive care among patients with SCD in developed countries does not easily translate to the adoption of these recommendations globally, which must take into account the local epidemiology of infections, available vaccines and population-specific vaccine efficacy, environment, health care behaviors, and cultural beliefs, as these are all factors that play a complex role in the manifestation of SCD and the prevention of infectious disease morbidity.
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Affiliation(s)
- Stephen K Obaro
- Department of pediatrics, Division of Pediatric Infectious Diseases, University of Nebraska Medical Center, Omaha, Nebraska.,Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska.,International Foundation Against Infectious Diseases in Nigeria (IFAIN), Millennium Plaza, Central Business Area, Abuja, Nigeria.,Department of Pediatrics, University of Abuja Teaching Hospital, Gwagwalada, Nigeria
| | - P Y Iroh Tam
- Pediatric Infectious Diseases and Immunology, University of Minnesota, Minneapolis, Minnesota
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26
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Iroh Tam PY, Hernandez-Alvarado N, Schleiss MR, Hassan-Hanga F, Onuchukwu C, Umoru D, Obaro SK. Molecular Detection of Streptococcus pneumoniae on Dried Blood Spots from Febrile Nigerian Children Compared to Culture. PLoS One 2016; 11:e0152253. [PMID: 27007889 PMCID: PMC4805257 DOI: 10.1371/journal.pone.0152253] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/11/2016] [Indexed: 02/02/2023] Open
Abstract
Background Nigeria has one of the highest burdens of pneumococcal disease in the world, but accurate surveillance is lacking. Molecular detection of infectious pathogens in dried blood spots (DBS) is an ideal method for surveillance of infections in resource-limited settings because of its low cost, minimal blood volumes involved, and ease of storage at ambient temperature. Our study aim was to evaluate a Streptococcus pneumoniae real-time polymerase chain reaction (rt-PCR) assay on DBS from febrile Nigerian children on Whatman 903 and FTA filter papers, compared to the gold standard of culture. Methods Between September 2011 to May 2015, blood was collected from children 5 years of age or under who presented to six hospital study sites throughout northern and central Nigeria with febrile illness, and inoculated into blood culture bottles or spotted onto Whatman 903 or FTA filter paper. Culture and rt-PCR were performed on all samples. Results A total of 537 DBS specimens from 535 children were included in the study, of which 15 were culture-positive for S. pneumoniae. The rt-PCR assay detected S. pneumoniae in 12 DBS specimens (2.2%). One positive rt-PCR result was identified in a culture-negative specimen from a high-risk subject, and two positive rt-PCR results were negative on repeat testing. Six culture-confirmed cases of S. pneumoniae bacteremia were missed. Compared to culture, the overall sensitivities of Whatman 903 and FTA DBS for detection of S. pneumoniae were 57.1% (95% CI 18.4–90.1%) and 62.5% (95% CI 24.5–91.5%), respectively. Nonspecific amplification was noted in an additional 22 DBS (4.1%). Among these, six were positive for a non-S. pneumoniae pathogen on culture. Conclusions Rt-PCR was able to detect S. pneumoniae from clinical DBS specimens, including from a culture-negative specimen. Our findings show promise of this approach as a surveillance diagnostic, but also raise important cautionary questions. Several DBS specimens were detected as S. pneumoniae by rt-PCR despite growth of a non-S. pneumoniae pathogen on culture. A precise definition of what constitutes a positive result is required to avoid falsely over-identifying specimens.
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Affiliation(s)
- Pui-Ying Iroh Tam
- Division of Pediatric Infectious Diseases and Immunology, University of Minnesota Masonic Children’s Hospital, Minneapolis, Minnesota, United States of America
- Center for Infectious Diseases, Microbiology and Translational Research, Minneapolis, Minnesota, United States of America
- * E-mail:
| | - Nelmary Hernandez-Alvarado
- Center for Infectious Diseases, Microbiology and Translational Research, Minneapolis, Minnesota, United States of America
| | - Mark R. Schleiss
- Division of Pediatric Infectious Diseases and Immunology, University of Minnesota Masonic Children’s Hospital, Minneapolis, Minnesota, United States of America
- Center for Infectious Diseases, Microbiology and Translational Research, Minneapolis, Minnesota, United States of America
| | | | - Chuma Onuchukwu
- Department of Paediatrics, Federal Medical Center, Keffi, Nasarawa, Nigeria
| | - Dominic Umoru
- Department of Paediatrics, Nyanya General Hospital, Abuja, Nigeria
| | - Stephen K. Obaro
- Department of Pediatrics, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
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Obaro SK, Daniel Y, Lawson JO, Hsu WW, Dada J, Essen U, Ibrahim K, Akindele A, Brooks K, Olanipekun G, Ajose T, Stewart CE, Inusa BPD. Sickle-Cell Disease in Nigerian Children: Parental Knowledge and Laboratory Results. Public Health Genomics 2016; 19:102-7. [PMID: 26991896 DOI: 10.1159/000444475] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 02/05/2016] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Sickle-cell disease (SCD) is the most common inherited genetic disorder in sub-Saharan Africa, and it is associated with early mortality and lifelong morbidity. Early diagnosis is essential for instituting appropriate care and preventive therapy. OBJECTIVE To compare parental knowledge or perception of their offspring's hemoglobin phenotype prior to testing and actual validated laboratory test results. METHODS In a prospective community-based survey, we assessed parental knowledge of their children's hemoglobin phenotype and corroborated this with the results from a laboratory confirmatory test determined by high-performance liquid chromatography. RESULTS We screened 10,126 children aged less than 5 years. A total of 163 (1.6%) parents indicated that their offspring had been previously tested and had knowledge of the child's hemoglobin genotype. However, 51 (31.2%) of 163 parents of children who had been previously tested did not know the result of their offspring's test, and 18 (35.3%) of these 51 children were found to have SCD. Of those who claimed previous knowledge, 25 (15.3%) of 163 reported incorrect results. Overall, we identified 272 (2.76%) new cases from 9,963 children who had not been previously tested. CONCLUSION There is the need to promote public awareness about SCD and the benefit of early diagnosis, quality assurance in laboratory diagnosis and institution of sustainable patient care pathways.
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Affiliation(s)
- Stephen K Obaro
- Division of Pediatric Infectious Diseases, University of Nebraska Medical Center, Omaha, Nebr., USA
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McGann PT, Tshilolo L, Santos B, Tomlinson GA, Stuber S, Latham T, Aygun B, Obaro SK, Olupot‐Olupot P, Williams TN, Odame I, Ware RE. Hydroxyurea Therapy for Children With Sickle Cell Anemia in Sub-Saharan Africa: Rationale and Design of the REACH Trial. Pediatr Blood Cancer 2016; 63:98-104. [PMID: 26275071 PMCID: PMC4825070 DOI: 10.1002/pbc.25705] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 07/19/2015] [Indexed: 01/01/2023]
Abstract
BACKGROUND Sickle cell anemia (SCA) is an inherited hematological disorder that causes a large but neglected global health burden, particularly in Africa. Hydroxyurea represents the only available disease-modifying therapy for SCA, and has proven safety and efficacy in high-resource countries. In sub-Saharan Africa, there is minimal use of hydroxyurea, due to lack of data, absence of evidence-based guidelines, and inexperience among healthcare providers. PROCEDURE A partnership was established between investigators in North America and sub-Saharan Africa, to develop a prospective multicenter research protocol designed to provide data on the safety, feasibility, and benefits of hydroxyurea for children with SCA. RESULTS The Realizing Effectiveness Across Continents with Hydroxyurea (REACH, ClinicalTrials.gov NCT01966731) trial is a prospective, phase I/II open-label dose escalation study of hydroxyurea that will treat a total of 600 children age 1-10 years with SCA: 150 at each of four different clinical sites within sub-Saharan Africa (Angola, Democratic Republic of Congo, Kenya, and Uganda). The primary study endpoint will be severe hematological toxicities that occur during the fixed-dose treatment phase. REACH has an adaptive statistical design that allows for careful assessment of toxicities to accurately identify a safe hydroxyurea dose. CONCLUSIONS REACH will provide data that address critical gaps in knowledge for the treatment of SCA in sub-Saharan Africa. By developing local expertise with the use of hydroxyurea and helping to establish treatment guidelines, the REACH trial results will have the potential to transform care for children with SCA in Africa.
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Affiliation(s)
| | | | | | | | - Susan Stuber
- Cincinnati Children's Hospital Medical CenterCincinnatiOhio
| | - Teresa Latham
- Cincinnati Children's Hospital Medical CenterCincinnatiOhio
| | - Banu Aygun
- Cohen Children's Medical CenterNew Hyde ParkNew York
| | | | | | - Thomas N. Williams
- KEMRI/Wellcome Trust Research ProgrammeKilifiKenya,Department of MedicineImperial CollegeLondonUK
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Affiliation(s)
- Stephen K Obaro
- Division of Pediatric Infectious Diseases, Children's Hospital & Medical Center, Department of Pediatrics, College of Medicine, University of Nebraska Medical Center, Omaha, NE 68114, USA.
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Affiliation(s)
- Shirley Delair
- University of Nebraska Medical Center, Division of Pediatric Infectious Diseases, Children's Hospital Medical Center, Omaha, NE 68114, USA
| | - Stephen K Obaro
- University of Nebraska Medical Center, Division of Pediatric Infectious Diseases, Children's Hospital Medical Center, Omaha, NE 68114, USA.
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Abstract
Group B streptococcus (GBS) disease is the leading cause of neonatal sepsis in developed countries and has high case fatality rates. In developing countries, however, the burden of GBS is less clear; this is due to a lack of studies using optimal diagnostic, clinical and laboratory techniques and is complicated by the wide availability of non-prescription antibiotics to the general population and in peripartum patients. There is an urgent need for prospective, population-based surveillance to provide an accurate assessment of neonatal GBS disease burden in developing countries, which remains largely unrecognized, and consequently obscures the potential relevance of GBS vaccination in these populations. Preliminary data on GBS vaccines are promising as a preventive tool for neonatal GBS infection, more so than any other currently available public health initiative. However, how do we assess the true impact of a GBS vaccine without accurate surveillance data on the real burden of disease?
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Affiliation(s)
- Pui-Ying Iroh Tam
- a 1 University of Minnesota Masonic Children's Hospital, Minneapolis, MN, USA
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Ezeanolue EE, Obiefune MC, Yang W, Obaro SK, Ezeanolue CO, Ogedegbe GG. Comparative effectiveness of congregation- versus clinic-based approach to prevention of mother-to-child HIV transmission: study protocol for a cluster randomized controlled trial. Implement Sci 2013; 8:62. [PMID: 23758933 PMCID: PMC3700826 DOI: 10.1186/1748-5908-8-62] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 06/04/2013] [Indexed: 01/13/2023] Open
Abstract
Background A total of 22 priority countries have been identified by the WHO that account for 90% of pregnant women living with HIV. Nigeria is one of only 4 countries among the 22 with an HIV testing rate for pregnant women of less than 20%. Currently, most pregnant women must access a healthcare facility (HF) to be screened and receive available prevention of mother-to-child HIV transmission (PMTCT) interventions. Finding new approaches to increase HIV testing among pregnant women is necessary to realize the WHO/ President's Emergency Plan for AIDS Relief (PEPFAR) goal of eliminating new pediatric infections by 2015. Methods This cluster randomized trial tests the comparative effectiveness of a congregation-based Healthy Beginning Initiative (HBI) versus a clinic-based approach on the rates of HIV testing and PMTCT completion among a cohort of church attending pregnant women. Recruitment occurs at the level of the churches and participants (in that order), while randomization occurs only at the church level. The trial is unblinded, and the churches are informed of their randomization group. Eligible participants, pregnant women attending study churches, are recruited during prayer sessions. HBI is delivered by trained community health nurses and church-based health advisors and provides free, integrated on-site laboratory tests (HIV plus hemoglobin, malaria, hepatitis B, sickle cell gene, syphilis) during a church-organized ‘baby shower.’ The baby shower includes refreshments, gifts exchange, and an educational game show testing participants’ knowledge of healthy pregnancy habits in addition to HIV acquisition modes, and effective PMTCT interventions. Baby receptions provide a contact point for follow-up after delivery. This approach was designed to reduce barriers to screening including knowledge, access, cost and stigma. The primary aim is to evaluate the effect of HBI on the HIV testing rate among pregnant women. The secondary aims are to evaluate the effect of HBI on the rate of HIV testing among male partners of pregnant women and the rate of PMTCT completion among HIV-infected pregnant women. Discussion Results of this study will provide further understanding of the most effective strategies for increasing HIV testing among pregnant women in hard-to-reach communities. Trial Registration Clinicaltrials.gov, NCT01795261
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Affiliation(s)
- Echezona E Ezeanolue
- Department of Pediatrics, University of Nevada School of Medicine, 2040 West Charleston Boulevard, Las Vegas, NV, USA.
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Khoo SK, Petillo D, Parida M, Tan AC, Resau JH, Obaro SK. Host response transcriptional profiling reveals extracellular components and ABC (ATP-binding cassette) transporters gene enrichment in typhoid fever-infected Nigerian children. BMC Infect Dis 2011; 11:241. [PMID: 21914192 PMCID: PMC3189140 DOI: 10.1186/1471-2334-11-241] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 09/13/2011] [Indexed: 12/18/2022] Open
Abstract
Background Salmonella enterica serovar Typhi (S. Typhi) is a human-specific pathogen that causes typhoid fever, and remains a global health problem especially in developing countries. Its pathogenesis is complex and host response is poorly understood. In Africa, typhoid fever can be a major cause of morbidity in young infected children. The onset of the illness is insidious and clinical diagnosis is often unreliable. Gold standard blood culture diagnostic services are limited, thus rapid, sensitive, and affordable diagnostic test is essential in poor-resourced clinical settings. Routine typhoid fever vaccination is highly recommended but currently licensed vaccines provide only 55-75% protection. Recent epidemiological studies also show the rapid emergence of multi-drug resistant S. Typhi strains. High-throughput molecular technologies, such as microarrays, can dissect the molecular mechanisms of host responses which are S. Typhi-specific to provide a comprehensive genomic component of immunological responses and suggest new insights for diagnosis and treatment. Methods Global transcriptional profiles of S. Typhi-infected young Nigerian children were obtained from their peripheral blood and compared with that of other bacteremic infections using Agilent gene expression microarrays. The host-response profiles of the same patients in acute vs. convalescent phases were also determined. The top 96-100 differentially-expressed genes were identified and four genes were validated by quantitative real-time PCR. Gene clusters were obtained and functional pathways were predicted by DAVID (Database for Annotation, Visualization and Integrated Discovery). Results Transcriptional profiles from S. Typhi-infected children could be distinguished from those of other bacteremic infections. Enriched gene clusters included genes associated with extracellular peptides/components such as lipocalin (LCN2) and systemic immune response which is atypical in bacterial invasion. Distinct gene expression profiles can also be obtained from acute vs. convalescent phase during typhoid fever infection. We found novel down-regulation of ABC (ATP-binding cassette) transporters genes such as ABCA7, ABCC5, and ABCD4 and ATPase activity as the highest enriched pathway. Conclusions We identified unique extracellular components and ABC transporters gene enrichments in typhoid fever-infected Nigerian children, which have never been reported. These enriched gene clusters may represent novel targeted pathways to improve diagnostic, prognostic, therapeutic and next-generation vaccine strategies for typhoid fever in Africa.
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Affiliation(s)
- Sok Kean Khoo
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, East Lansing, MI, USA.
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Williams TN, Obaro SK. Sickle cell disease and malaria morbidity: a tale with two tails. Trends Parasitol 2011; 27:315-20. [PMID: 21429801 DOI: 10.1016/j.pt.2011.02.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 02/15/2011] [Accepted: 02/18/2011] [Indexed: 01/19/2023]
Abstract
More than 230,000 children are born in Africa with sickle cell disease (SCD) each year: approximately 85% of all affected births worldwide. Although malaria is commonly viewed as a major problem for African patients with this condition, questions still remain about its relative importance as a cause of ill heath and death. In the absence of definitive studies investigating the contribution of malaria to morbidity and mortality in African children with SCD, policy makers will continue to lack the evidence on which to base appropriate management guidelines.
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Affiliation(s)
- Thomas N Williams
- KEMRI Centre for Geographic Medicine Research (Coast), Kilifi, Kenya.
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Booth C, Inusa B, Obaro SK. Infection in sickle cell disease: a review. Int J Infect Dis 2009; 14:e2-e12. [PMID: 19497774 DOI: 10.1016/j.ijid.2009.03.010] [Citation(s) in RCA: 164] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Revised: 03/09/2009] [Accepted: 03/11/2009] [Indexed: 01/30/2023] Open
Abstract
Infection is a significant contributor to morbidity and mortality in sickle cell disease (SCD). The sickle gene confers an increased susceptibility to infection, especially to certain bacterial pathogens, and at the same time infection provokes a cascade of SCD-specific pathophysiological changes. Historically, infection is a major cause of mortality in SCD, particularly in children, and it was implicated in 20-50% of deaths in prospective cohort studies over the last 20 years. Worldwide, it remains the leading cause of death, particularly in less developed nations. In developed countries, measures to prevent and effectively treat infection have made a substantial contribution to improvements in survival and quality of life, and are continually being developed and extended. However, progress continues to lag in less developed countries where the patterns of morbidity and mortality are less well defined and implementation of preventive care is poor. This review provides an overview of how SCD increases susceptibility to infections, the underlying mechanisms for susceptibility to specific pathogens, and how infection modifies the outcome of SCD. It also highlights the challenges in reducing the global burden of mortality in SCD.
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Affiliation(s)
- Catherine Booth
- Guy's, King's & St Thomas' Medical School, King's College London, London, UK
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Obaro SK, Ota MO. Sense and the science of childhood immunization: Can we achieve more with less? Vaccine 2006; 24:6460-7. [PMID: 16911848 DOI: 10.1016/j.vaccine.2006.06.051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2006] [Revised: 06/17/2006] [Accepted: 06/20/2006] [Indexed: 11/28/2022]
Abstract
The threat of biological terrorism with small pox virus and a global influenza pandemic in the face of limited vaccine supply recently stimulated research into the evaluation of fractional dose vaccine regimens, with promising immunogenicity results. While this approach is not new, it has been less applied to vaccines for less sensational but nevertheless, significant killer diseases. This manuscript provides an overview of the basics of immunization as it applies to the current practice of immunization in children, comments on the untapped avenues for cost reduction of vaccine delivery, and the potential for saving more lives with currently available resources.
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Affiliation(s)
- Stephen K Obaro
- Children's Hospital of Pittsburgh, 3705 Fifth Avenue, Pittsburgh, PA 15213-2583, USA.
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Abstract
Bacterial pneumonia is a substantial cause of childhood morbidity and mortality worldwide, but determination of pathogen-specific burden remains a challenge. In less developed settings, the WHO recommended guidelines are useful for initiating care, but are non-specific. Blood culture has low sensitivity, while radiological findings are non-specific and do not discriminate between viral and bacterial causes of pneumonia. In vaccine probe studies, efficacy is dependent on the specificity of the study outcome to detect pneumonia and the impact of the vaccine on the selected outcome, and may underestimate the true burden of bacterial pneumonia. The rising incidence of antibiotic resistance, emerging respiratory pathogens, potential replacement pneumococcal disease following widespread introduction of pneumococcal polysaccharide-protein conjugate vaccine, the limited specificity of chest radiography, and the poor sensitivity of blood culture are substantial obstacles to accurate surveillance. We provide an overview of the diagnostic challenges of bacterial pneumonia and highlight the need for refining the current diagnostic approach to ensure adequate epidemiological surveillance of childhood pneumonia and the success, or otherwise, of any immunisation strategies.
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Affiliation(s)
- Stephen K Obaro
- Children's Hospital of Pittsburgh, Pittsburgh, PA 15213-2583, USA.
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Cutts FT, Zaman SMA, Enwere G, Jaffar S, Levine OS, Okoko JB, Oluwalana C, Vaughan A, Obaro SK, Leach A, McAdam KP, Biney E, Saaka M, Onwuchekwa U, Yallop F, Pierce NF, Greenwood BM, Adegbola RA. Efficacy of nine-valent pneumococcal conjugate vaccine against pneumonia and invasive pneumococcal disease in The Gambia: randomised, double-blind, placebo-controlled trial. Lancet 2005; 365:1139-46. [PMID: 15794968 DOI: 10.1016/s0140-6736(05)71876-6] [Citation(s) in RCA: 649] [Impact Index Per Article: 34.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Pneumonia is estimated to cause 2 million deaths every year in children. Streptococcus pneumoniae is the most important cause of severe pneumonia. We aimed to assess the efficacy of a nine-valent pneumococcal conjugate vaccine in children. METHODS We undertook a randomised, placebo-controlled, double-blind trial in eastern Gambia. Children age 6-51 weeks were randomly allocated three doses of either pneumococcal conjugate vaccine (n=8718) or placebo (8719), with intervals of at least 25 days between doses. Our primary outcome was first episode of radiological pneumonia. Secondary endpoints were clinical or severe clinical pneumonia, invasive pneumococcal disease, and all-cause admissions. Analyses were per protocol and intention to treat. FINDINGS 529 children assigned vaccine and 568 allocated placebo were not included in the per-protocol analysis. Results of per-protocol and intention-to-treat analyses were similar. By per-protocol analysis, 333 of 8189 children given vaccine had an episode of radiological pneumonia compared with 513 of 8151 who received placebo. Pneumococcal vaccine efficacy was 37% (95% CI 27-45) against first episode of radiological pneumonia. First episodes of clinical pneumonia were reduced overall by 7% (95% CI 1-12). Efficacy of the conjugate vaccine was 77% (51-90) against invasive pneumococcal disease caused by vaccine serotypes, 50% (21-69) against disease caused by all serotypes, and 15% (7-21) against all-cause admissions. We also found an efficacy of 16% (3-28) against mortality. 110 serious adverse events arose in children given the pneumococcal vaccine compared with 131 in those who received placebo. INTERPRETATION In this rural African setting, pneumococcal conjugate vaccine has high efficacy against radiological pneumonia and invasive pneumococcal disease, and can substantially reduce admissions and improve child survival. Pneumococcal conjugate vaccines should be made available to African infants.
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Affiliation(s)
- F T Cutts
- Medical Research Council Laboratories, Banjul, The Gambia
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Obaro SK, Losikoff P, Harwell J, Pugatch D. Failure of serial human immunodeficiency virus type 1 DNA polymerase chain reactions to identify human immunodeficiency virus type 1 clade A/G. Pediatr Infect Dis J 2005; 24:183-4. [PMID: 15702052 DOI: 10.1097/01.inf.0000151040.57772.40] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The most commonly used test to screen for human immunodeficiency virus type 1 (HIV-1) infection in HIV-exposed infants in the United States is HIV-1 qualitative DNA polymerase chain reaction (PCR). However, the commercially available HIV-1 DNA PCR lack optimal sensitivity to detect non-subtype B subtypes of HIV-1. We report here HIV-1 infection in a West African infant that went undetected by serial HIV-1 DNA PCR tests.
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Affiliation(s)
- Stephen K Obaro
- Division of Pediatric Infectious Diseases, Brown Medical School, Rhode Island Hospital, Providence, RI, USA
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Deubzer HE, Obaro SK, Newman VO, Adegbola RA, Greenwood BM, Henderson DC. Colostrum Obtained from Women Vaccinated with Pneumococcal Vaccine during Pregnancy Inhibits Epithelial Adhesion ofStreptococcus pneumoniae. J Infect Dis 2004; 190:1758-61. [PMID: 15499530 DOI: 10.1086/424597] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2004] [Accepted: 05/12/2004] [Indexed: 11/03/2022] Open
Abstract
Prevention of nasopharyngeal colonization may reduce the burden of pneumococcal infection during infancy. Colostrum obtained from Gambian mothers who had been vaccinated with either Pneumovax II or Mengivax A&C (n=8 per group) during pregnancy was examined for inhibition of adherence of Streptococcus pneumoniae serotypes 6B and 14 to pharyngeal epithelial cells in vitro. Pneumococcal adherence was significantly reduced in the presence of breast milk (P< or =.0001 for S. pneumoniae serotype 14; P=.036 for serotype 6B), independent of the concentration of secretory IgA antibodies. Maternal vaccination with polyvalent pneumococcal polysaccharide vaccine boosts the capacity of colostrum to inhibit adherence of pneumococci to pharyngeal epithelial cells. In breast-feeding populations, maternal vaccination might prevent pneumococcal disease in young infants.
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Affiliation(s)
- Hedwig E Deubzer
- Imperial College, Faculty of Medicine, Department of Immunology, Chelsea and Westminster Hospital, London, United Kingdom
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Obaro SK, Deubzer HE, Newman VO, Adegbola RA, Greenwood BM, Henderson DC. Serotype-specific pneumococcal antibodies in breast milk of Gambian women immunized with a pneumococcal polysaccharide vaccine during pregnancy. Pediatr Infect Dis J 2004; 23:1023-9. [PMID: 15545857 DOI: 10.1097/01.inf.0000143651.54880.09] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND In breast-feeding populations, immunization during pregnancy with pneumococcal polysaccharide offers a potentially useful approach to preventing pneumococcal disease in young infants. METHODS Breast milk samples were collected at 0, 2, 4 and 6 months after delivery from Gambian women vaccinated during pregnancy (24-32 weeks gestation) with Pneumovax II (n = 56) or Mengivax A&C (n = 57). Specimens were examined for secretory immunoglobulin A (s-IgA) concentration, subclass distribution and avidity specific to pneumococcal serotypes 4, 6B, 14, 19F and 23F and the antigen mixture in Pneumovax II by enzyme-linked immunosorbent assay. Colostral s-IgA and IgG concentrations in paired maternal sera were compared. RESULTS Colostral s-IgA concentrations specific to all pneumococcal polysaccharide antigens investigated were significantly higher (P < 0.05) among Pneumovax II vaccinees. Titers specific to serotypes 4, 6B and 14 and the vaccine formula remained significantly higher during 6 months, and those for 19F were higher during 4 months. Significantly higher concentrations of vaccine antigen-specific s-IgA antibody were sustained for 6 months after delivery (P = 0.011). Comparison of colostral s-IgA and IgG in serum revealed a significant correlation only among Mengivax A&C vaccinees for pneumococcal polysaccharide 23F (rs= 0.68; P < or = 0.0001). Vaccination elicited trends toward increased s-IgA2, reaching significance for serotype 14 and the vaccine formula. Immunization elicited significantly higher s-IgA avidities specific to all pneumococcal polysaccharide antigens studied during 6 months. CONCLUSIONS The public health value of immunization during pregnancy with pneumococcal polysaccharide vaccine in breast-feeding populations warrants further evaluation, particularly in populations with a high incidence of pneumococcal disease in early infancy.
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Affiliation(s)
- Stephen K Obaro
- Imperial College, School of Science, Technology and Medicine, Department of Immunology, Chelsea and Westminster Hospital, London, United Kingdom
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Abstract
Children infected by HIV-1 are particularly vulnerable to severe, recurrent, or unusual infections by vaccine-preventable pathogens. Routine immunisations seem to be generally safe for HIV-1-infected children, but responses may be suboptimal. Early HIV-1-induced immune attrition associated with viral replication may particularly interfere with the development of memory responses. In high HIV-1 prevalence regions, the accumulation of susceptible hosts may compromise disease-control efforts. Although early control of viral replication through treatment with highly active therapy may preserve immune function and responses to routine childhood vaccines, availability is limited in the areas most affected. In this review, we provide an overview of the immunogenicity and efficacy of childhood vaccines in HIV-1-infected children. The possible immunological bases for defective responses are discussed; unanswered questions and the need for further research are delineated.
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Affiliation(s)
- S K Obaro
- Division of Pediatric Infectious Diseases, Rhode Island Hospital, Department of Pediatrics, Brown Medical School, Providence, RI 02903, USA.
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Abstract
The dawn of the 21st century ushered in spectacular advances in vaccine production technology. However, the benefits of these developments have been largely confined to the world's most affluent and least afflicted. Of the 14 million deaths that occur world-wide in children aged less than 5 years, over 95% of these occur in developing countries and at least 70% are caused by infections for which vaccines are already available in other countries. While impoverished countries do not have a right to be assisted with the provision of funds or vaccines by affluent developed countries, an initiative for the global eradication of a vaccine preventable disease, requires a global effort. Assisting developing countries to achieve such goals should be a high priority for wealthy nations, even if only to protect their own populations. With improved international travel, not only can newly emerging diseases spread across the globe, but pathogens eliminated from one population can be re-imported by travellers or immigrants. In contrast, the recent decline in acceptance of immunisation programmes in developed countries are secondary to strong anti-vaccine movements attributing unproven adverse reactions to vaccines, placing these life-saving vaccines into disrepute. A fertile ground for propagation of these ideologies is created by parents who in their lifetime may not have seen a child killed or maimed from bacterial meningitis or measles and therefore have little understanding of the risk-benefit of vaccination. The development and deployment of vaccines must be a global effort as are the treaties for global disarmament for weapons of mass destruction.
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Affiliation(s)
- S K Obaro
- Division of Pediatric Infectious Diseases, Rhode Island Hospital, 593 Eddy Street, Providence 02903, USA.
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Obaro SK. Dexamethasone in acute bacterial meningitis. Lancet 2002; 360:1609-10; author reply 1610-1. [PMID: 12443641 DOI: 10.1016/s0140-6736(02)11553-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Obaro SK, Enwere GC, Deloria M, Jaffar S, Goldblatt D, Brainsby K, Hallander H, McInnes P, Greenwood BM, McAdam KPWJ. Safety and immunogenicity of pneumococcal conjugate vaccine in combination with diphtheria, tetanus toxoid, pertussis and Haemophilus influenzae type b conjugate vaccine. Pediatr Infect Dis J 2002; 21:940-7. [PMID: 12394817 DOI: 10.1097/00006454-200210000-00011] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Pneumococcal polysaccharide/protein conjugate vaccines (PnCV) are immunogenic and effective in infancy. However, an addition to the nine currently recommended vaccine injections during the first year of life of African children may be a deterrent to participation in a PnCV program. Thus we have evaluated the safety and immunogenicity of a 9-valent PnCV (Wyeth Lederle Pediatrics and Vaccines) mixed with diphtheria, tetanus toxoid, cell pertussis and type b (TETRAMUNE). METHODS Healthy Gambian infants were randomized at the age of 2 months to receive three doses 1 month apart of either (1) placebo reconstituted in TETRAMUNE in the right thigh (control) or (2) PnCV in the left thigh and TETRAMUNE in the right thigh (separate) or (3) PnCV reconstituted in TETRAMUNE as a single injection in the right thigh (combined). The vaccines were given together with routine Expanded Program on Immunization vaccines. Adverse reactions were recorded after vaccination, and antibody concentrations were measured by enzyme-linked immunosorbent assays. RESULTS Local induration and tenderness were observed more commonly at the site of injection of TETRAMUNE than at the site of injection with PnCV after each dose of vaccination. Swelling at the site of injection was encountered more frequently at the site of administration of TETRAMUNE than at the site of administration PnCV ( P< 0.00001 for Doses 1 and 2 and P< 0.0009 for Dose 3). Swelling at the site of administration of TETRAMUNE mixed with PnCV was comparable with that observed for TETRAMUNE alone. Although most mothers reported that the babies "felt hot" 24 h after each injection, febrile reactions (temperature, >or=38 degrees C) were infrequent and resolved with antipyretics. Geometric mean titer for anti-polyribosylribitol phosphate antibody was 11.6 microg/ml [95% confidence limits (95% CI), 9.2, 14.6] in the control group and comparable with 13.3 microg/ml (95% CI 11.0, 16.0) in the combined group and significantly higher at 17.9 microg/ml (95% CI 14.7, 21.9; P= 0.01) in the separate group. Geometric mean concentrations of serotype-specific pneumococcal antibodies were higher in the combined group than the separate group for all nine serotypes. Antibody responses to diphtheria and pertussis antigens were similar in all groups. Anti-tetanus toxoid antibody concentrations were lowest in the combined group (6.66 IU/ml, 95% CI 5.77, 7.68 in the control group; 5.15 IU/ml, 95% CI 4.39, 6.03 in the combined group; P= 0.02). However, all vaccinees achieved protective antibody values. CONCLUSION The combination of TETRAMUNE and PnCV is safe and immunogenic.
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Abstract
Pneumococcal disease is now the leading cause of vaccine-preventable bacterial disease in children worldwide. Although a pneumococcal polysaccharide vaccine has been available for over three decades, its use has been limited due to poor immunogenicity in the most vulnerable children, aged less than 2 years. The prevalence of pneumococcal disease worldwide and the alarming global escalation of multiresistant strains of Streptococcus pneumoniae (pneumococcus) during the past decade have provided the impetus for the development and application of a new pneumococcal vaccine. The outstanding success of Haemophilus influenzae type b (Hib) conjugate vaccine in the control of invasive Hib disease is a reason to be optimistic that the pneumococcal conjugate vaccines will achieve similar results for the control of invasive pneumococcal disease. Remarkable efficacy against invasive pneumococcal disease with a seven-valent pneumococcal conjugate vaccine was demonstrated in infants and toddlers in the USA, and in February 2000 the first pneumococcal conjugate vaccine was licensed. Licensure and widespread use is likely to follow in other countries in which there is a need and the means to afford this live-saving vaccine. Active disease surveillance must be sustained globally, while active research, development of other multivalent conjugate formulations and the search for new candidate protein-based vaccines are in progress.
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Affiliation(s)
- S K Obaro
- Department of Paediatrics, Imperial College School of Medicine, London, W2 1PG, UK.
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