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Plumb ID, Lecy D, Singleton R, Engel MC, Hirschfeld M, Keck JW, Klejka J, Rudolph KM, Hennessy TW, Bruce MG. Invasive Haemophilus influenzae Serotype a Infection in Children: Clinical Description of an Emerging Pathogen-Alaska, 2002-2014. Pediatr Infect Dis J 2018; 37:298-303. [PMID: 29189672 PMCID: PMC6362456 DOI: 10.1097/inf.0000000000001764] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Invasive infections from Haemophilus influenzae serotype a (Hia) have been reported with increasing frequency, especially among indigenous populations. However, there are limited population-based studies of clinical severity. We studied invasive Hia infections in Alaska to determine clinical characteristics, mortality and sequelae. METHODS We defined an invasive Hia infection as the first detection of Hia from a usually sterile site in a child <10 years of age from Alaska. We identified cases using the Alaska Invasive Bacterial Diseases Surveillance System and reviewed medical charts up to 2 years after reported illness. RESULTS We identified invasive Hia infections in 36 children, 28 (78%) <1 year old, 34 (94%) living in an Alaskan village and 25 (69%) without documented underlying illness. Overlapping clinical presentations included meningitis in 15 children (42%); bacteremia and pneumonia in 10 children (28%); and bone, joint or soft tissue infections in 10 children (22%). In 4 other children, no source of invasive infection was identified. Intensive care was provided for 11 children (31%); 12 children (33%) required surgical intervention. One year after infection, 4 children (11%) had died from Hia, and 5 children (14%) had ongoing neurologic sequelae. CONCLUSIONS Invasive Hia infections in Alaska occurred predominantly in Alaska Native infants in rural communities. Although one-third of children had preexisting conditions, most cases occurred without known comorbidity. Clinical syndromes were frequently severe. One year after infection, 1 in 4 children had either died or had neurologic sequelae. An effective vaccine would prevent significant morbidity and mortality in affected populations.
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52
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Shoukat A, Van Exan R, Moghadas SM. Cost-effectiveness of a potential vaccine candidate for Haemophilus influenzae serotype 'a'. Vaccine 2018; 36:1681-1688. [PMID: 29459062 DOI: 10.1016/j.vaccine.2018.01.047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 01/12/2018] [Accepted: 01/17/2018] [Indexed: 02/06/2023]
Abstract
The preceding decade has witnessed the emergence of severe community-acquired acute infections caused by Haemophilus influenzae serotype a (Hia), with alarming incidence rates in North America, particularly among indigenous populations. The remarkable success of Hib conjugate vaccine over the past 20 years signify the development of an Hia vaccine candidate as a prevention measure to reduce the incidence of invasive Hia disease. However, quantifications of the long-term epidemiologic and economic impacts of vaccination are needed to inform decision on investment in Hia vaccine development and immunization programs. We sought to evaluate the cost-effectiveness of an Hia vaccine with a similar routine infant immunization schedules currently in practice for Hib in Canada. We developed and parameterized an agent-based simulation model using age-specific incidence rates reported for Nunavut, a Canadian territory with predominantly aboriginal populations. Our results, based on statistical analyses of the incremental cost-effectiveness ratio, show that an Hia conjugate vaccine is highly cost-effective. Sustaining an immunization program with vaccine coverages of 77% for primary series and 93% for booster dose over a 10-year period reduces the incidence of invasive disease by 63.8% on average from 9.97 to 3.61 cases, per 100,000 population. The overall costs of disease management in year 10 are reduced by 53.4% from CDN $1.863 million (95% CI: $1.229-$2.519 M) to CDN $0.868 million (95% CI: $0.627-$1.120 M). The findings suggest an important role for a conjugate vaccine in managing Hia disease as a growing public health threat.
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Affiliation(s)
- Affan Shoukat
- Agent-Based Modelling Laboratory, York University, Toronto, Ontario M3J 1P3, Canada.
| | - Robert Van Exan
- Immunization & Policy Translation, 16 Fire Route 105, Trent Lakes, Ontario K0M 1A0, Canada
| | - Seyed M Moghadas
- Agent-Based Modelling Laboratory, York University, Toronto, Ontario M3J 1P3, Canada
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53
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Giufrè M, Cardines R, Brigante G, Orecchioni F, Cerquetti M. Emergence of Invasive Haemophilus influenzae Type A Disease in Italy. Clin Infect Dis 2018; 64:1626-1628. [PMID: 28369218 DOI: 10.1093/cid/cix234] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 03/14/2017] [Indexed: 11/14/2022] Open
Abstract
We report on the first detection of 2 cases of invasive Haemophilus influenzae type a (Hia) disease in Italy. The cases were sustained by the same Hia "strain" belonging to the ST23 clone that has previously been reported only outside Europe. The emergence of invasive Hia disease is of concern.
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Affiliation(s)
- Maria Giufrè
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome
| | - Rita Cardines
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome
| | | | - Francesca Orecchioni
- Clinical Analysis Laboratory, Section of Microbiology, Ospedali Riuniti di Ancona, Italy
| | - Marina Cerquetti
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome
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54
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Baek JY, Geissner A, Rathwell DCK, Meierhofer D, Pereira CL, Seeberger PH. A modular synthetic route to size-defined immunogenic Haemophilus influenzae b antigens is key to the identification of an octasaccharide lead vaccine candidate. Chem Sci 2017; 9:1279-1288. [PMID: 29675174 PMCID: PMC5887106 DOI: 10.1039/c7sc04521b] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 12/05/2017] [Indexed: 01/03/2023] Open
Abstract
A Haemophilus influenzae b vaccine lead antigen was identified by the immunological evaluation of chemically precisely defined capsular polysaccharide repeating unit oligosaccharides.
The first glycoconjugate vaccine using isolated glycans was licensed to protect children from Haemophilus influenzae serotype b (Hib) infections. Subsequently, the first semisynthetic glycoconjugate vaccine using a mixture of antigens derived by polymerization targeted the same pathogen. Still, a detailed understanding concerning the correlation between oligosaccharide chain length and the immune response towards the polyribosyl-ribitol-phosphate (PRP) capsular polysaccharide that surrounds Hib remains elusive. The design of semisynthetic and synthetic Hib vaccines critically depends on the identification of the minimally protective epitope. Here, we demonstrate that an octasaccharide antigen containing four repeating disaccharide units resembles PRP polysaccharide in terms of immunogenicity and recognition by anti-Hib antibodies. Key to this discovery was the development of a modular synthesis that enabled access to oligosaccharides up to decamers. Glycan arrays containing the synthetic oligosaccharides were used to analyze anti-PRP sera for antibodies. Conjugates of the synthetic antigens and the carrier protein CRM197, which is used in licensed vaccines, were employed in immunization studies in rabbits.
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Affiliation(s)
- J Y Baek
- Max Planck Institute of Colloids and Interfaces , 14476 Potsdam , Germany . ;
| | - A Geissner
- Max Planck Institute of Colloids and Interfaces , 14476 Potsdam , Germany . ; .,Freie Universität Berlin , Department of Chemistry and Biochemistry , 14195 Berlin , Germany
| | - D C K Rathwell
- Max Planck Institute of Colloids and Interfaces , 14476 Potsdam , Germany . ; .,Freie Universität Berlin , Department of Chemistry and Biochemistry , 14195 Berlin , Germany
| | - D Meierhofer
- Max-Planck Institute for Molecular Genetics (MPIMG) , 14195 Berlin , Germany
| | - C L Pereira
- Max Planck Institute of Colloids and Interfaces , 14476 Potsdam , Germany . ;
| | - P H Seeberger
- Max Planck Institute of Colloids and Interfaces , 14476 Potsdam , Germany . ; .,Freie Universität Berlin , Department of Chemistry and Biochemistry , 14195 Berlin , Germany
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55
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Takano C, Seki M, Kim DW, Kilgore PE, Fuwa K, Takahashi K, Inazaki T, Hayakawa S. Molecular Serotype-Specific Identification of Non-type b Haemophilus influenzae by Loop-Mediated Isothermal Amplification. Front Microbiol 2017; 8:1877. [PMID: 29046666 PMCID: PMC5632651 DOI: 10.3389/fmicb.2017.01877] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Accepted: 09/13/2017] [Indexed: 11/26/2022] Open
Abstract
Over the past four decades, the incidence of meningitis caused by Haemophilus influenzae in children has decreased due to widespread vaccination against H. influenzae type b (Hib). The incidence of invasive diseases due to H. influenzae types not included in the vaccines, however, has increased. At present, there are a limited number of diagnostics available to detect non-type b H. influenzae. To address this issue, we developed a rapid, simple, and cost-effective method for detecting serotypes of H. influenzae. We designed LAMP primer sets based on published sequences for H. influenzae capsular types a, c, d, e, and f. The assay was evaluated to determine test reactivity, specificity, and sensitivity. To support its use in patients with suspected meningitis, we evaluated the detection limit of the non-Hib serotype specific LAMP assay using bacterial genomic DNA-spiked cerebrospinal fluid (CSF) specimens. The reactivity and specificity of the LAMP assays were confirmed using six serotypes and non-typeable H. influenzae strains, plus eight strains of other Haemophilus species and non-Haemophilus genera. The detection limits of the LAMP assay for capsular types a, c, d, e, and f were 102, 102, 102, 103, and 10 copies per reaction, while those of the PCR assay were 104, 104, 103, 103, and 104 genome copies per reaction, respectively. Using DNA-spiked CSF specimens, the detection limit of the LAMP assay was equivalent to that using purified DNA as the template. However, the detection limit of the PCR was reduced from 103 to 104 genome copies per reaction for serotype d and from 103 to 105 genome copies per reaction for serotype e. To the best of our knowledge, this is the first report of a serotype-specific identification assay for H. influenzae using the LAMP method. Our results suggest the potential of LAMP methods for patients with suspected meningitis in resource-limited laboratories or public health surveillance systems.
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Affiliation(s)
- Chika Takano
- Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, Tokyo, Japan
| | - Mitsuko Seki
- Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, Tokyo, Japan
| | - Dong Wook Kim
- Department of Pharmacy, College of Pharmacy, Hanyang University, Ansan, South Korea.,Institute of Pharmacological Research, Hanyang University, Ansan, South Korea
| | - Paul E Kilgore
- Department of Pharmacy Practice, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, United States
| | - Kazumasa Fuwa
- Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, Tokyo, Japan
| | - Koji Takahashi
- Medical Devices Solutions Vehicle, Kaneka Corporation, Hyogo, Japan
| | | | - Satoshi Hayakawa
- Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, Tokyo, Japan
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56
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Cox AD, Williams D, Cairns C, St Michael F, Fleming P, Vinogradov E, Arbour M, Masson L, Zou W. Investigating the candidacy of a capsular polysaccharide-based glycoconjugate as a vaccine to combat Haemophilus influenzae type a disease: A solution for an unmet public health need. Vaccine 2017; 35:6129-6136. [PMID: 28951087 DOI: 10.1016/j.vaccine.2017.09.055] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 09/17/2017] [Indexed: 11/29/2022]
Abstract
After the introduction of the glycoconjugate vaccine based upon the capsular polysaccharide ofHaemophilus influenzaetype b in the mid 1980s there was a remarkable decrease in the number of invasive cases reported for this organism. Since the 1990s several groups have observed the emergence ofHaemophilus influenzaetype a (Hia), especially in indigenous communities in the northern regions of Canada and Alaska, to a stage where a solution is warranted to prevent further unnecessary deaths due to this pathogen. A glycoconjugate vaccine solution based upon the type a capsular polysaccharide (CPS) was investigated pre-clinically in an effort to illustrate the proof of concept for this approach. In this study we describe the growth of Hia and the isolation, purification and conjugation of the CPS to several carrier proteins. The resulting glycoconjugates were immunised in mice and rabbits provoking sera that facilitated bactericidal killing against all type a strains that we tested. This study has illustrated the pre-clinical proof of concept of a glycoconjugate vaccine based on the CPS of Hia asa solution to this emerging disease.
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Affiliation(s)
- Andrew D Cox
- Vaccine Program, Human Health Therapeutics Portfolio, National Research Council, Ottawa, ON K1A 0R6, Canada.
| | - Dean Williams
- Vaccine Program, Human Health Therapeutics Portfolio, National Research Council, Ottawa, ON K1A 0R6, Canada
| | - Chantelle Cairns
- Vaccine Program, Human Health Therapeutics Portfolio, National Research Council, Ottawa, ON K1A 0R6, Canada
| | - Frank St Michael
- Vaccine Program, Human Health Therapeutics Portfolio, National Research Council, Ottawa, ON K1A 0R6, Canada
| | - Perry Fleming
- Vaccine Program, Human Health Therapeutics Portfolio, National Research Council, Ottawa, ON K1A 0R6, Canada
| | - Evgeny Vinogradov
- Vaccine Program, Human Health Therapeutics Portfolio, National Research Council, Ottawa, ON K1A 0R6, Canada
| | - Mélanie Arbour
- Vaccine Program, Human Health Therapeutics Portfolio, National Research Council, Ottawa, ON K1A 0R6, Canada
| | - Luke Masson
- Vaccine Program, Human Health Therapeutics Portfolio, National Research Council, Ottawa, ON K1A 0R6, Canada
| | - Wei Zou
- Vaccine Program, Human Health Therapeutics Portfolio, National Research Council, Ottawa, ON K1A 0R6, Canada
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57
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Caporarello N, Olivieri M, Cristaldi M, Scalia M, Toscano MA, Genovese C, Addamo A, Salmeri M, Lupo G, Anfuso CD. Blood-Brain Barrier in a Haemophilus influenzae Type a In Vitro Infection: Role of Adenosine Receptors A 2A and A 2B. Mol Neurobiol 2017; 55:5321-5336. [PMID: 28921456 DOI: 10.1007/s12035-017-0769-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 09/07/2017] [Indexed: 01/15/2023]
Abstract
The blood-brain barrier (BBB) is mainly made up of tightly connected microvascular endothelial cells (BMECs), surrounded by pericytes (BMPCs) which regulate BBB tightness by providing soluble factors that control endothelial proliferation. Haemophilus influenzae type a (Hia) is able to reach the BBB, crossing it, thus causing meningitis. In this study, by using an in vitro model of BBB, performed with human BMECs and human BMPCs in co-culture, we demonstrated that, after Hia infection, the number of hBMPCs decreased whereas the number of hBMECs increased in comparison with non-infected cells. SEM and TEM images showed that Hia was able to enter hBMECs and reduce TEER and VE-cadherin expression. When the cells were infected in presence of SCH58261 and PSB603 but not DPCPX, an increase in TEER values was observed thus demonstrating that A2A and A2B adenosine receptors play a key role in BBB dysfunction. These results were confirmed by the use of adenosine receptor agonists CGS21680, CCPA, and NECA. In infected co-cultures cAMP and VEGF increased and TEER reduction was counter-balanced by VEGF-R1 or VEGF-R2 antibodies. Moreover, the phosphorylated CREB and Rho-A significantly increased in infected hBMECs and hBMPCs and the presence of SCH58261 and PSB603 significantly abrogated the phosphorylation. In conclusion, this study demonstrated that the infection stimulated A2A and A2B adenosine receptors in hBMECs and hBMPCs thus inducing the pericytes to release large amounts of VEGF. The latter could be responsible for both, pericyte detachment and endothelial cell proliferation, thus provoking BBB impairment.
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Affiliation(s)
- N Caporarello
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy
| | - M Olivieri
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy
| | - M Cristaldi
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy
| | - M Scalia
- Section of Biology and Genetic, Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy
| | - M A Toscano
- Section of Microbiology, Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy
| | - C Genovese
- Section of Microbiology, Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy
| | - A Addamo
- Section of Microbiology, Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy
| | - M Salmeri
- Section of Microbiology, Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy.
| | - G Lupo
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy.
| | - C D Anfuso
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy
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58
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Charania NA, Moghadas SM. Modelling the effects of booster dose vaccination schedules and recommendations for public health immunization programs: the case of Haemophilus influenzae serotype b. BMC Public Health 2017; 17:705. [PMID: 28903749 PMCID: PMC5598080 DOI: 10.1186/s12889-017-4714-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 09/05/2017] [Indexed: 12/26/2022] Open
Abstract
Background Haemophilus influenzae serotype b (Hib) has yet to be eliminated despite the implementation of routine infant immunization programs. There is no consensus regarding the number of primary vaccine doses and an optimal schedule for the booster dose. We sought to evaluate the effect of a booster dose after receiving the primary series on the long-term disease incidence. Methods A stochastic model of Hib transmission dynamics was constructed to compare the long-term impact of a booster vaccination and different booster schedules after receiving the primary series on the incidence of carriage and symptomatic disease. We parameterized the model with available estimates for the efficacy of Hib conjugate vaccine and durations of both vaccine-induced and naturally acquired immunity. Results We found that administering a booster dose substantially reduced the population burden of Hib disease compared to the scenario of only receiving the primary series. Comparing the schedules, the incidence of carriage for a 2-year delay (on average) in booster vaccination was comparable or lower than that observed for the scenario of booster dose within 1 year after primary series. The temporal reduction of symptomatic disease was similar in the two booster schedules, suggesting no superiority of one schedule over the other in terms of reducing the incidence of symptomatic disease. Conclusions The findings underscore the importance of a booster vaccination for continued decline of Hib incidence. When the primary series provides a high level of protection temporarily, delaying the booster dose (still within the average duration of protection conferred by the primary series) may be beneficial to maintain longer-term protection levels and decelerate the decline of herd immunity in the population. Electronic supplementary material The online version of this article (10.1186/s12889-017-4714-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nadia A Charania
- Department of Public Health, Auckland University of Technology, 640 Great South Road, Manukau, Auckland, 2025, New Zealand
| | - Seyed M Moghadas
- Agent-Based Modelling Laboratory, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
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59
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Tsang RSW, Ulanova M. The changing epidemiology of invasive Haemophilus influenzae disease: Emergence and global presence of serotype a strains that may require a new vaccine for control. Vaccine 2017; 35:4270-4275. [PMID: 28666758 DOI: 10.1016/j.vaccine.2017.06.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 05/23/2017] [Accepted: 06/01/2017] [Indexed: 10/19/2022]
Abstract
BACKGROUND More than two decades after the implementation of the Hib conjugate vaccine in North America, Haemophilus influenzae serotype a (Hia) has emerged as a significant cause of invasive disease in Indigenous communities. However, little is known about the global presence of this pathogen. METHODS We interrogated the H. influenzae Multi-Locus Sequence Typing (MLST) website (https://pubmlst.org/hinfluenzae/) by selecting for serotype a records. We also updated our previous literature review on this subject matter. RESULTS Hia has been reported from at least 35 countries on six major continents. However, most Hia diseases were associated with Indigenous communities. Clonal analysis identified two clonal populations with one typified as ST-23 responsible for most invasive disease in North America and being the predominant clone described on the H. influenzae MLST website. Incidence of invasive Hia disease in Indigenous communities in North America are similar to the rates of Hib disease reported prior to the Hib conjugate vaccine era. Hia causes severe clinical diseases, such as meningitis, septicaemia, pneumonia, and septic arthritis with case-fatality rates between 5.6% and 33% depending on the age of the patient and the genetic makeup of the Hia strain. CONCLUSION Although invasive Hia disease can be found globally, the current epidemiological data suggest that this infection predominantly affects Indigenous communities in North America. The clinical disease of Hia and the clonal nature of the bacteria resemble that of Hib. The high incidence of invasive Hia disease in Indigenous communities, along with potential fatality and severe sequelae causing long-term disability in survivors, may support the development of a new Hia conjugate vaccine for protection against this infection similar in design to the one introduced in the 1990s to control invasive Hib disease.
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Affiliation(s)
- Raymond S W Tsang
- Vaccine Preventable Bacterial Diseases, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada.
| | - Marina Ulanova
- Northern Ontario School of Medicine, Lakehead University, Thunder Bay, Ontario, Canada
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60
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Abstract
Meningitis caused by Haemophilus influenzae type b (Hib) was eliminated in Oman after the introduction of Hib vaccine in 2001. However, a case of H. influenzae type a meningitis was diagnosed in a child from Oman in 2015, which highlights the need to monitor the incidence of invasive non-Hib H. influenzae disease.
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61
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Barreto L, Cox AD, Ulanova M, Bruce MG, Tsang RSW. The emerging Haemophilus influenzae serotype a infection and a potential vaccine: Implementation science in action. CANADA COMMUNICABLE DISEASE REPORT = RELEVE DES MALADIES TRANSMISSIBLES AU CANADA 2017; 43:85-88. [PMID: 29770070 PMCID: PMC5864301 DOI: 10.14745/ccdr.v43i05a01] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Haemophilus influenzae serotype b (Hib) was a major cause of meningitis in children until Hib conjugate vaccine was introduced into the routine infant immunization program and Hib disease in children was almost eliminated. In Alaska, northern Canada and other countries with Indigenous peoples, H. influenzae serotype a (Hia) has emerged as a significant cause of pneumonia, meningitis and septic arthritis especially in children under 24 months of age. A joint government initiative between the Public Health Agency of Canada (PHAC) and the National Research Council of Canada (NRC) was carried out to assess whether an Hia vaccine could be developed for the common good. The initiative included strategic partnerships with clinician researchers in Thunder Bay, Ontario who provide health services to Indigenous people and the Artic Investigations Program (AIP) of the United States Centers for Disease Control and Prevention (CDC) in Alaska. This government initiated and funded research identified that the development of an Hia vaccine is possible and ongoing surveillance that includes strain characterization is essential to understand the potential spread of Hia in North America and around the world.
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Affiliation(s)
- L Barreto
- Human Health Therapeutics Portfolio, National Research Council of Canada, Ottawa, ON
| | - AD Cox
- Human Health Therapeutics Portfolio, National Research Council of Canada, Ottawa, ON
| | - M Ulanova
- Northern Ontario School of Medicine, Lakehead University, Thunder Bay, ON
| | - MG Bruce
- Arctic Investigations Program, Division of Preparedness and Emerging Infections, US Centers for Disease Control and Prevention (CDC), Anchorage, AK
| | - RSW Tsang
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB
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62
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Characteristics of invasive Haemophilus influenzae serotype a (Hia) from Nunavik, Canada and comparison with Hia strains in other North American Arctic regions. Int J Infect Dis 2017; 57:104-107. [DOI: 10.1016/j.ijid.2017.02.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/02/2017] [Accepted: 02/05/2017] [Indexed: 11/21/2022] Open
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63
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Dalecki AG, Crawford CL, Wolschendorf F. Copper and Antibiotics: Discovery, Modes of Action, and Opportunities for Medicinal Applications. Adv Microb Physiol 2017; 70:193-260. [PMID: 28528648 DOI: 10.1016/bs.ampbs.2017.01.007] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Copper is a ubiquitous element in the environment as well as living organisms, with its redox capabilities and complexation potential making it indispensable for many cellular functions. However, these same properties can be highly detrimental to prokaryotes and eukaryotes when not properly controlled, damaging many biomolecules including DNA, lipids, and proteins. To restrict free copper concentrations, all bacteria have developed mechanisms of resistance, sequestering and effluxing labile copper to minimize its deleterious effects. This weakness is actively exploited by phagocytes, which utilize a copper burst to destroy pathogens. Though administration of free copper is an unreasonable therapeutic antimicrobial itself, due to insufficient selectivity between host and pathogen, small-molecule ligands may provide an opportunity for therapeutic mimicry of the immune system. By modulating cellular entry, complex stability, resistance evasion, and target selectivity, ligand/metal coordination complexes can synergistically result in high levels of antibacterial activity. Several established therapeutic drugs, such as disulfiram and pyrithione, display remarkable copper-dependent inhibitory activity. These findings have led to development of new drug discovery techniques, using copper ions as the focal point. High-throughput screens for copper-dependent inhibitors against Mycobacterium tuberculosis and Staphylococcus aureus uncovered several new compounds, including a new class of inhibitors, the NNSNs. In this review, we highlight the microbial biology of copper, its antibacterial activities, and mechanisms to discover new inhibitors that synergize with copper.
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Affiliation(s)
- Alex G Dalecki
- The University of Alabama at Birmingham, Birmingham, AL, United States
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64
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Characterisation of invasive clinical Haemophilus influenzae isolates in Queensland, Australia using whole-genome sequencing. Epidemiol Infect 2017; 145:1727-1736. [PMID: 28260537 DOI: 10.1017/s0950268817000450] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Haemophilus influenzae is an important aetiological organism of both adult and child respiratory disease. The number of non-typeable (NTHi) invasive H. influenzae isolates referred to the Queensland (QLD) Public Health Microbiology laboratory has increased notably year-by-year. In this study we used whole-genome sequencing to molecularly characterise 100 referred invasive H. influenzae, including 74 NTHi isolates over a 15-year period, observing the carriage of capsular and putative virulence genes, including the major adhesins, antimicrobial resistance genes and population diversity. Encapsulated isolates were largely clonal, however NTHi isolates displayed high genetic variability by MLST and single nucleotide polymorphism typing with no dominant clone observed. The only mechanism for β-lactam resistance identified in the QLD isolates was β-lactamase production. No single set of virulence determinants was conclusively associated with invasive QLD NTHi isolates.
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65
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Abstract
PURPOSE OF REVIEW The increase in drug-resistant community-acquired pneumonia (CAP) is an important problem all over the world. This article explores the current state of antimicrobial resistance of different bacteria that cause CAP and also assesses risk factors to identify those pathogens. RECENT FINDINGS In the last two decades, it has been documented that there is a significant increase in drug-resistant Streptococcus pneumoniae and other bacteria causing CAP. The most important risk factors are overuse of antibiotics, prior hospitalization, and lung comorbidities. The direct consequences can be severe, including prolonged stays in hospital, increased costs, and morbi-mortality. However, drug-resistant CAP declined after the introduction of the pneumococcal conjugate vaccine. This review found an increase in resistance to the antibiotics used in CAP, and the risk factor can be used for identifying patients with drug-resistant CAP and initiate appropriate treatment. Judicious use of antibiotics and the development of effective new vaccines are needed.
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Affiliation(s)
- Francisco Arancibia
- Servicio de Medicina Respiratoria, Instituto Nacional Del Tórax and Unidad de Enfermedades Respiratorias, Facultad de Medicina Oriente, Universidad de Chile, J.M.Infante 717, Providencia, Santiago of Chile, Chile.
| | - Mauricio Ruiz
- Departamento de Medicina, Hospital Clínico U. de Chile, Universidad de Chile, Av. Independencia 1027, Independencia, Providencia, Santiago of Chile, Chile
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66
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Tuyama M, Corrêa-Antônio J, Schlackman J, Marsh JW, Rebelo MC, Cerqueira EO, Nehab M, Kegele F, Carmo GF, Thielmann DC, Barroso PF, Harrison LH, Barroso DE. Invasive Haemophilus influenzae disease in the vaccine era in Rio de Janeiro, Brazil. Mem Inst Oswaldo Cruz 2017; 112:196-202. [PMID: 28225904 PMCID: PMC5319370 DOI: 10.1590/0074-02760160391] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 11/23/2016] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Haemophilus influenzae (Hi) serotype b (Hib) conjugate vaccine was incorporated into the infant immunisation schedule in Brazil in 1999, where Hib was one of the major etiologic sources of community-acquired bacterial meningitis. OBJECTIVES The purpose of this study is to describe the molecular epidemiology of invasive Hi disease in Rio de Janeiro state, Brazil, before and after vaccine introduction. METHODS Surveillance data from 1986 to 2014 were analysed. Hi isolates recovered from cerebrospinal fluid (CSF) or blood from 1993 to 2014 were serotyped by slide agglutination, genotyped by multilocus sequence typing (MLST), and the capsule type evaluation, differentiation of serologically non-typeable isolates, and characterisation of the capsule (cap) locus was done by polymerase chain reaction. Antimicrobial susceptibility testing was performed using E-test. FINDINGS From 1986 to 1999 and from 2000 to 2014, 2580 and 197 (42% without serotype information) confirmed cases were reported, respectively. The case fatality rate was 17% and did not correlate with the strain. Hib and b- variant isolates belonged to ST-6, whereas serotype a isolates belonged to the ST-23 clonal complex. Serotype a appeared to emerge during the 2000s. Non-encapsulated isolates were non-clonal and distinct from the encapsulated isolates. Ampicillin-resistant isolates were either of serotype b or were non-encapsulated, and all of them were β-lactamase-positive but amoxicillin-clavulanic acid susceptible. MAIN CONCLUSIONS Although Hi meningitis became a relatively rare disease in Rio de Janeiro after the introduction of the Hib conjugate vaccine, the isolates recovered from patients have become more diverse. These results indicate the need to implement an enhanced surveillance system to continue monitoring the impact of the Hib conjugate vaccine.
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Affiliation(s)
- Mari Tuyama
- Fundação Oswaldo Cruz-Fiocruz, Instituto Oswaldo Cruz, Laboratório de Epidemiologia e Sistemática Molecular, Rio de Janeiro, RJ, Brasil.,Universidade Federal do Rio de Janeiro, Faculdade de Medicina, Rio de Janeiro, RJ, Brasil
| | - Jessica Corrêa-Antônio
- Fundação Oswaldo Cruz-Fiocruz, Instituto Oswaldo Cruz, Laboratório de Epidemiologia e Sistemática Molecular, Rio de Janeiro, RJ, Brasil
| | - Jessica Schlackman
- University of Pittsburgh, School of Medicine and Graduate School of Public Health, Infectious Diseases Epidemiology Research Unit, Pittsburgh, PA, United States of America
| | - Jane W Marsh
- University of Pittsburgh, School of Medicine and Graduate School of Public Health, Infectious Diseases Epidemiology Research Unit, Pittsburgh, PA, United States of America
| | - Maria C Rebelo
- Secretaria de Estado de Saúde do Rio de Janeiro, Assessoria de Meningites, Rio de Janeiro, RJ, Brasil
| | - Elaine O Cerqueira
- Secretaria de Estado de Saúde do Rio de Janeiro, Assessoria de Meningites, Rio de Janeiro, RJ, Brasil
| | - Márcio Nehab
- Fundação Oswaldo Cruz-Fiocruz, Instituto Fernandes Figueira, Rio de Janeiro, RJ, Brasil
| | - Fabíola Kegele
- Fundação Oswaldo Cruz-Fiocruz, Instituto Fernandes Figueira, Rio de Janeiro, RJ, Brasil
| | | | | | - Paulo F Barroso
- Universidade Federal do Rio de Janeiro, Faculdade de Medicina, Rio de Janeiro, RJ, Brasil
| | - Lee H Harrison
- University of Pittsburgh, School of Medicine and Graduate School of Public Health, Infectious Diseases Epidemiology Research Unit, Pittsburgh, PA, United States of America
| | - David E Barroso
- Fundação Oswaldo Cruz-Fiocruz, Instituto Oswaldo Cruz, Laboratório de Epidemiologia e Sistemática Molecular, Rio de Janeiro, RJ, Brasil
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67
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First Complete Genome Sequence of Haemophilus influenzae Serotype a. GENOME ANNOUNCEMENTS 2017; 5:5/3/e01506-16. [PMID: 28104664 PMCID: PMC5255917 DOI: 10.1128/genomea.01506-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Haemophilus influenzae is an important human pathogen that primarily infects small children. In recent years, H. influenzae serotype a has emerged as a significant cause of invasive disease among indigenous populations. Here, we present the first complete whole-genome sequence of H. influenzae serotype a.
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68
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Thorgrimson J, Ulanova M. Haemophilus influenzae type a as a cause of paediatric septic arthritis. JMM Case Rep 2016; 3:e005064. [PMID: 28348786 PMCID: PMC5343144 DOI: 10.1099/jmmcr.0.005064] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Accepted: 08/19/2016] [Indexed: 12/13/2022] Open
Abstract
Introduction: Incidence rates of invasive Haemophilus influenzae serotype b disease have decreased significantly since the introduction of the Hib vaccine; however, the rates in indigenous populations remain disproportionately high, specifically in the paediatric population. Additionally, with the decline of type b invasive infections, there has been a rebound in the incidence of invasive infections caused by other strains of H. influenzae, particularly serotype a. Case presentation: We present a paediatric case of septic arthritis caused by H. influenzae type a in a toddler that was fully resolved following antibiotic therapy. This report adds to other reports of septic arthritis in indigenous populations as shown through a review of recently documented H. influenzae type a septic arthritis cases. Conclusion: Socio-economic risk factors for invasive H. influenzae type a disease, such as poverty, poor housing conditions, overcrowding, smoking and substance abuse during pregnancy, as well as the need for H. influenzae type a immunization of vulnerable populations, are discussed.
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Affiliation(s)
- Joelle Thorgrimson
- Northern Ontario School of Medicine , 955 Oliver Road, Thunder Bay, ON P7B 5E1 , Canada
| | - Marina Ulanova
- Northern Ontario School of Medicine , 955 Oliver Road, Thunder Bay, ON P7B 5E1 , Canada
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69
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Samraj RS, Fergie J. Septic Arthritis and Hemarthroses Caused by Haemophilus influenzae Serotype A in Children. Infect Dis Rep 2016. [PMCID: PMC5062627 DOI: 10.4081/idr.2016.6494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Invasive disease caused by Haemophilus influenzae serotype A (Hia) is rare in children. Clinical syndromes caused by Hia include meningitis, sepsis and respiratory tract infections. Septic arthritis is rare in children with invasive Hia infection and hemarthrosis has not been described in the published literature. We report a case of septic arthritis and hemarthrosis caused by Hia infection in a 2.5 year-old-boy and review invasive Hia infection in children.
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70
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Konini A, Nix E, Ulanova M, Moghadas SM. Dynamics of naturally acquired antibody against Haemophilus influenzae type a capsular polysaccharide in a Canadian Aboriginal population. Prev Med Rep 2016; 3:145-50. [PMID: 27419007 PMCID: PMC4929236 DOI: 10.1016/j.pmedr.2016.01.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Severe infections caused by Haemophilus influenzae type a (Hia) have reached alarming rates in some Canadian Aboriginal communities. We sought to estimate the frequency of exposure to this pathogen and timelines for boosting protective antibodies. We developed a model of secondary antigenic challenge (natural exposure), and used data for anti-Hia antibodies in serum samples of healthy and immunocompromised adults in a population of Northwestern Ontario, Canada. We parameterized the model with available estimates from previous studies for the decay rate of antibody and its protective levels against both Hia carriage and invasive disease. Simulations were initialized using antibody concentrations from data. We investigated both the duration of immunity without secondary antigenic challenge and the average time between subsequent exposures to Hia. When there was no new natural exposure, serum antibody concentrations in healthy Aboriginal individuals decreased below the level (1 μg/ml) assumed for protection against invasive Hia disease 3 years after primary exposure. This period was shorter (about 2 years) for Aboriginal individuals suffering from chronic renal failure. We estimated that a new antigenic challenge occurs once in 5 and 2 years for healthy and immunocompromised Aboriginal individuals, respectively. More frequent natural exposure was required to maintain protective antibody levels for non-Aboriginal individuals compared to Aboriginal individuals. The findings suggest that frequent boosting of natural immunity is required to maintain the anti-Hia antibody levels protecting against invasive Hia disease, particularly in individuals with underlying medical conditions. This information has important implications for immunization when an anti-Hia vaccine becomes available. Frequent natural exposure to Hia is required to maintain protective immunity. Epigenetic factors may affect formation of natural immunity in Aboriginal people. Further data pertaining to immunological correlates of Hia are needed. Modeling can inform timelines of boosting immunity and vaccination policies.
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Affiliation(s)
- Angjelina Konini
- Agent-Based Modelling Laboratory, York University, 4700 Keele St., Toronto, Ontario M3J 1P3, Canada
- Corresponding author.
| | - Eli Nix
- Northern Ontario School of Medicine, Lakehead University, Thunder Bay, Ontario, Canada
| | - Marina Ulanova
- Northern Ontario School of Medicine, Lakehead University, Thunder Bay, Ontario, Canada
| | - Seyed M. Moghadas
- Agent-Based Modelling Laboratory, York University, 4700 Keele St., Toronto, Ontario M3J 1P3, Canada
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71
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Simulating Immune Interference on the Effect of a Bivalent Glycoconjugate Vaccine against Haemophilus influenzae Serotypes "a" and "b". CANADIAN JOURNAL OF INFECTIOUS DISEASES & MEDICAL MICROBIOLOGY 2016; 2016:5486869. [PMID: 27366171 PMCID: PMC4904591 DOI: 10.1155/2016/5486869] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 11/12/2015] [Indexed: 11/17/2022]
Abstract
Objective. We sought to evaluate the immune responses to a bivalent Haemophilus influenzae glycoconjugate vaccine against serotypes “a” (Hia) and “b” (Hib) in the presence of the preexisting immunity to Hib. Methods. We developed a stochastic simulation model of humoral immune response to investigate the antigenic challenge of a bivalent combined glycoconjugate vaccine and a bivalent unimolecular glycoconjugate vaccine. We compared simulation outcomes in the absence of any preexisting immunity with an already primed immune response having specific memory B cells and/or anti-Hib antibodies. Results. The simulation results show that the preexisting immune responses to Hib or carrier protein (CP) may significantly impede the production of anti-Hia antibodies by a unimolecular vaccine. In contrast, the production of anti-Hia antibodies using a combined vaccine is inhibited only in the presence of CP immune responses. Conclusions. Preexisting immunity to Hib and CP may play a critical role in the development of immune responses against Hia or Hib using bivalent combined and unimolecular vaccine formulations. Our results suggest that a bivalent combined glycoconjugate vaccine with a carrier protein not previously used in Hib conjugate vaccines may be an effective formulation for generating immune responses to protect against both Hib and Hia infections.
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72
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Tsang RSW, Li YA, Mullen A, Baikie M, Whyte K, Shuel M, Tyrrell G, Rotondo JAL, Desai S, Spika J. Laboratory characterization of invasive Haemophilus influenzae isolates from Nunavut, Canada, 2000-2012. Int J Circumpolar Health 2016; 75:29798. [PMID: 26765260 PMCID: PMC4712320 DOI: 10.3402/ijch.v75.29798] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 11/30/2015] [Accepted: 12/07/2015] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND With invasive Haemophilus influenzae serotype b (Hib) disease controlled by vaccination with conjugate Hib vaccines, there is concern that invasive disease due to non-serotype b strains may emerge. OBJECTIVE This study characterized invasive H. influenzae (Hi) isolates from Nunavut, Canada, in the post-Hib vaccine era. METHODS Invasive H. influenzae isolates were identified by conventional methods at local hospitals; and further characterized at the provincial and federal public health laboratories, including detection of serotype antigens and genes, multi-locus sequence typing and antibiotic susceptibility. RESULTS Of the 89 invasive H. influenzae cases identified from 2000 to 2012, 71 case isolates were available for study. There were 43 serotype a (Hia), 12 Hib, 2 Hic, 1 Hid, 1 Hie, 2 Hif and 10 were non-typeable (NT). All 43 Hia were biotype II, sequence type (ST)-23. Three related STs were found among the Hib isolates: ST-95 (n=9), ST-635 (n=2) and ST-44 (n=1). Both Hif belonged to ST-124 and the 2 Hic were typed as ST-9. The remaining Hid (ST-1288) and Hie (ST-18) belonged to 2 separate clones. Of the 10 NT strains, 3 were typed as ST-23 and the remaining 7 isolates each belonged to a unique ST. Eight Hib and 1 NT-Hi were found to be resistant to ampicillin due to β-lactamase production. No resistance to other antibiotics was detected. CONCLUSION During the period of 2000-2012, Hia was the predominant serotype causing invasive disease in Nunavut. This presents a public health concern due to an emerging clone of Hia as a cause of invasive H. influenzae disease and the lack of published guidelines for the prophylaxis of contacts. The clonal nature of Hia could be the result of spread within an isolated population, and/or unique characteristics of this strain to cause invasive disease. Further study of Hia in other populations may provide important information on this emerging pathogen. No antibiotic resistance was detected among Hia isolates; a small proportion of Hib and NT-Hi isolates demonstrated resistance to ampicillin due to β-lactamase production.
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Affiliation(s)
- Raymond S W Tsang
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba;
| | - Y Anita Li
- Centre for Immunization and Respiratory Infectious Diseases, Public Health Agency of Canada, Ottawa, Ontario
| | - Angie Mullen
- Department of Health, Government of Nunavut, Iqaluit, Nunavut
| | - Maureen Baikie
- Department of Health, Government of Nunavut, Iqaluit, Nunavut;
| | - Kathleen Whyte
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba
| | - Michelle Shuel
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba
| | - Gregory Tyrrell
- Provincial Laboratory for Public Health, Edmonton, Alberta, Canada
| | - Jenny A L Rotondo
- Centre for Immunization and Respiratory Infectious Diseases, Public Health Agency of Canada, Ottawa, Ontario
| | - Shalini Desai
- Centre for Immunization and Respiratory Infectious Diseases, Public Health Agency of Canada, Ottawa, Ontario
| | - John Spika
- Centre for Immunization and Respiratory Infectious Diseases, Public Health Agency of Canada, Ottawa, Ontario
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73
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Invasive disease due to Haemophilus influenzae type A in children in Canada's north: A priority for prevention. CANADIAN JOURNAL OF INFECTIOUS DISEASES & MEDICAL MICROBIOLOGY 2016; 26:291-2. [PMID: 26744583 PMCID: PMC4692295 DOI: 10.1155/2015/613820] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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74
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Konini A, Moghadas SM. Modelling the impact of vaccination on curtailing Haemophilus influenzae serotype 'a'. J Theor Biol 2015; 387:101-10. [PMID: 26453974 DOI: 10.1016/j.jtbi.2015.09.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 08/16/2015] [Accepted: 09/25/2015] [Indexed: 12/16/2022]
Abstract
Haemophilus influenzae serotype a (Hia) is a human-restricted bacterial pathogen transmitted via direct contacts with an infectious individual. Currently, there is no vaccine available for prevention of Hia, and the disease is treated with antibiotics upon diagnosis. With ongoing efforts for the development of an anti-Hia protein-polysaccharide conjugated vaccine, we sought to investigate the effect of vaccination on curtailing Hia infection. We present the first stochastic model of Hia transmission and control dynamics, and parameterize it using available estimates in the literature. Since both naturally acquired and vaccine-induced immunity wane with time, model simulations show three important results. First, vaccination of only newborns cannot eliminate the pathogen from the population, even when a booster program is implemented with a high coverage. Second, achieving and maintaining a sufficiently high level of herd immunity for pathogen elimination requires vaccination of susceptible individuals in addition to a high vaccination coverage of newborns. Third, for a low vaccination rate of susceptible individuals, a high coverage of booster dose may be needed to raise the level of herd immunity for Hia eradication. Our findings highlight the importance of vaccination and timely boosting of the individual׳s immunity within the expected duration of vaccine-induced protection against Hia. When an anti-Hia vaccine becomes available, enhanced surveillance of Hia incidence and herd immunity could help determine vaccination rates and timelines for booster doses necessary to eliminate Hia from affected populations.
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Affiliation(s)
- Angjelina Konini
- Department of Mathematics and Statistics, Agent-Based Modelling Laboratory, York University, Toronto, Ontario, Canada M3J 1P3.
| | - Seyed M Moghadas
- Department of Mathematics and Statistics, Agent-Based Modelling Laboratory, York University, Toronto, Ontario, Canada M3J 1P3
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75
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Slack MPE. A review of the role of Haemophilus influenzae in community-acquired pneumonia. Pneumonia (Nathan) 2015; 6:26-43. [PMID: 31641576 PMCID: PMC5922337 DOI: 10.15172/pneu.2015.6/520] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 03/04/2015] [Indexed: 01/01/2023] Open
Abstract
In an era when Haemophilus influenzae type b (Hib) conjugate vaccine is widely used, the incidence of Hib as a cause of community-acquired pneumonia (CAP) has dramatcally declined. Non-typeable H. influenzae (NTHi) strains and, occasionally, other encapsulated serotypes of H. influenzae are now the cause of the majority of invasive H. influenzae infectons, including bacteraemic CAP. NTHi have long been recognised as an important cause of lower respiratory tract infecton, including pneumonia, in adults, especially those with underlying diseases. The role of NTHi as a cause of non-bacteraemic CAP in children is less clear. In this review the evidence for the role of NTHi and capsulated strains of H. influenzae will be examined.
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Affiliation(s)
- Mary P E Slack
- 15Gold Coast Campus, Griffith University, Queensland, Australia.,25Institute of Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
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76
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Rostad CA, Berkowitz FE. Toddler with Fever and Grunting. J Pediatric Infect Dis Soc 2015; 4:370-2. [PMID: 26407254 DOI: 10.1093/jpids/piv016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2015] [Accepted: 02/24/2015] [Indexed: 11/13/2022]
Affiliation(s)
- Christina A Rostad
- Department of Pediatrics Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia
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77
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Multicenter Evaluation of the Bruker MALDI Biotyper CA System for the Identification of Clinical Aerobic Gram-Negative Bacterial Isolates. PLoS One 2015; 10:e0141350. [PMID: 26529504 PMCID: PMC4631355 DOI: 10.1371/journal.pone.0141350] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 10/06/2015] [Indexed: 11/19/2022] Open
Abstract
The prompt and accurate identification of bacterial pathogens is fundamental to patient health and outcome. Recent advances in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) have revolutionized bacterial identification in the clinical laboratory, but uniform incorporation of this technology in the U.S. market has been delayed by a lack of FDA-cleared systems. In this study, we conducted a multicenter evaluation of the MALDI Biotyper CA (MBT-CA) System (Bruker Daltonics Inc, Billerica, MA) for the identification of aerobic gram-negative bacteria as part of a 510(k) submission to the FDA. A total of 2,263 aerobic gram negative bacterial isolates were tested representing 23 genera and 61 species. Isolates were collected from various clinical sources and results obtained from the MBT-CA System were compared to DNA sequencing and/or biochemical testing. Isolates that failed to report as a "high confidence species ID" [log(score) ≥2.00] were re-tested using an extraction method. The MBT-CA System identified 96.8% and 3.1% of isolates with either a "high confidence" or a "low confidence" [log(score) value between 1.70 and <2.00] species ID, respectively. Two isolates did not produce acceptable confidence scores after extraction. The MBT-CA System correctly identified 99.8% (2,258/2,263) to genus and 98.2% (2,222/2,263) to species level. These data demonstrate that the MBT-CA System provides accurate results for the identification of aerobic gram-negative bacteria.
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78
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Nix EB, Williams K, Cox AD, St Michael F, Romero-Steiner S, Schmidt DS, McCready WG, Ulanova M. Naturally acquired antibodies against Haemophilus influenzae type a in Aboriginal adults, Canada. Emerg Infect Dis 2015; 21:273-9. [PMID: 25626129 PMCID: PMC4313637 DOI: 10.3201/eid2102.140722] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
High prevalence of invasive Hia disease among North American Aboriginal populations is more likely related to exposure than to inadequate immunity. In the post-Haemophilus influenzae type b (Hib) vaccine era that began in the 1980's, H. influenzae type a (Hia) emerged as a prominent cause of invasive disease in North American Aboriginal populations. To test whether a lack of naturally acquired antibodies may underlie increased rates of invasive Hia disease, we compared serum bactericidal activity against Hia and Hib and IgG and IgM against capsular polysaccharide between Canadian Aboriginal and non-Aboriginal healthy and immunocompromised adults. Both healthy and immunocompromised Aboriginal adults exhibited significantly higher bactericidal antibody titers against Hia than did non-Aboriginal adults (p = 0.042 and 0.045 respectively), with no difference in functional antibody activity against Hib. IgM concentrations against Hia were higher than IgG in most study groups; the inverse was true for antibody concentrations against Hib. Our results indicate that Aboriginal adults possess substantial serum bactericidal activity against Hia that is mostly due to IgM antibodies. The presence of sustained IgM against Hia suggests recent Hia exposure.
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79
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Akthar S, Patel DF, Beale RC, Peiró T, Xu X, Gaggar A, Jackson PL, Blalock JE, Lloyd CM, Snelgrove RJ. Matrikines are key regulators in modulating the amplitude of lung inflammation in acute pulmonary infection. Nat Commun 2015; 6:8423. [PMID: 26400771 PMCID: PMC4595997 DOI: 10.1038/ncomms9423] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 08/20/2015] [Indexed: 01/17/2023] Open
Abstract
Bioactive matrix fragments (matrikines) have been identified in a myriad of disorders, but their impact on the evolution of airway inflammation has not been demonstrated. We recently described a pathway where the matrikine and neutrophil chemoattractant proline–glycine–proline (PGP) could be degraded by the enzyme leukotriene A4 hydrolase (LTA4H). LTA4H classically functions in the generation of pro-inflammatory leukotriene B4, thus LTA4H exhibits opposing pro- and anti-inflammatory activities. The physiological significance of this secondary anti-inflammatory activity remains unknown. Here we show, using readily resolving pulmonary inflammation models, that loss of this secondary activity leads to more pronounced and sustained inflammation and illness owing to PGP accumulation. PGP elicits an exacerbated neutrophilic inflammation and protease imbalance that further degrades the extracellular matrix, generating fragments that perpetuate inflammation. This highlights a critical role for the secondary anti-inflammatory activity of LTA4H and thus has consequences for the generation of global LTA4H inhibitors currently being developed. Proteases degrade extracellular matrix during inflammation, releasing peptides that can recruit neutrophils. Here the authors show that degradation of such bioactive peptide by the enzyme leukotriene A4 hydrolase is critical to limit pulmonary inflammation during bacterial infection in mice.
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Affiliation(s)
- Samia Akthar
- Leukocyte Biology Section, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK
| | - Dhiren F Patel
- Leukocyte Biology Section, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK
| | - Rebecca C Beale
- Leukocyte Biology Section, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK
| | - Teresa Peiró
- Leukocyte Biology Section, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK
| | - Xin Xu
- Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham and Lung Health Center, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 3529, USA
| | - Amit Gaggar
- Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham and Lung Health Center, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 3529, USA.,Gregory Fleming James Cystic Fibrosis Center and Program in Protease and Matrix Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.,Birmingham V.A. Medical Center, Birmingham, Alabama 35294, USA
| | - Patricia L Jackson
- Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham and Lung Health Center, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 3529, USA
| | - J Edwin Blalock
- Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham and Lung Health Center, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 3529, USA.,Birmingham V.A. Medical Center, Birmingham, Alabama 35294, USA
| | - Clare M Lloyd
- Leukocyte Biology Section, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK
| | - Robert J Snelgrove
- Leukocyte Biology Section, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK
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80
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Immunological Features and Clinical Benefits of Conjugate Vaccines against Bacteria. J Immunol Res 2015; 2015:934504. [PMID: 26355657 PMCID: PMC4556328 DOI: 10.1155/2015/934504] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 07/27/2015] [Indexed: 11/17/2022] Open
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Kosikowska U, Korona-Głowniak I, Niedzielski A, Malm A. Nasopharyngeal and Adenoid Colonization by Haemophilus influenzae and Haemophilus parainfluenzae in Children Undergoing Adenoidectomy and the Ability of Bacterial Isolates to Biofilm Production. Medicine (Baltimore) 2015; 94:e799. [PMID: 25950686 PMCID: PMC4602522 DOI: 10.1097/md.0000000000000799] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Haemophili are pathogenic or opportunistic bacteria often colonizing the upper respiratory tract mucosa. The prevalence of Haemophilus influenzae (with serotypes distribution), and H. parainfluenzae in the nasopharynx and/or the adenoid core in children with recurrent pharyngotonsillitis undergoing adenoidectomy was assessed. Haemophili isolates were investigated for their ability to biofilm production.Nasopharyngeal swabs and the adenoid core were collected from 164 children who underwent adenoidectomy (2-5 years old). Bacteria were identified by the standard methods. Serotyping of H. influenzae was performed using polyclonal and monoclonal antisera. Biofilm formation was detected spectrophotometrically using 96-well microplates and 0.1% crystal violet.Ninety seven percent (159/164) children who underwent adenoidectomy were colonized by Haemophilus spp. The adenoid core was colonized in 99.4% (158/159) children, whereas the nasopharynx in 47.2% (75/159) children (P < 0.0001). In 32% (51/159) children only encapsulated (typeable) isolates of H. influenzae were identified, in 22.6% (36/159) children only (nonencapsulated) H. influenzae NTHi (nonencapsulated) isolates were present, whereas 7.5% (12/159) children were colonized by both types. 14.5% (23/159) children were colonized by untypeable (rough) H. influenzae. In 22% (35/159) children H. influenzae serotype d was isolated. Totally, 192 isolates of H. influenzae, 96 isolates of H. parainfluenzae and 14 isolates of other Haemophilus spp. were selected. In 20.1% (32/159) children 2 or 3 phenotypically different isolates of the same species (H. influenzae or H. parainfluenzae) or serotypes (H. influenzae) were identified in 1 child. 67.2% (129/192) isolates of H. influenzae, 56.3% (54/96) isolates of H. parainfluenzae and 85.7% (12/14) isolates of other Haemophilus spp. were positive for biofilm production. Statistically significant differences (P = 0.0029) among H. parainfluenzae biofilm producers and nonproducers in the adenoid core and the nasopharynx were detected.H. influenzae and H. parainfluenzae carriage rate was comparatively higher in the adenoid core than that in the nasopharynx in children undergoing adenoidectomy, suggesting that their involvement in chronic adenoiditis. The growth in the biofilm seems to be an important feature of haemophili colonizing the upper respiratory tract responsible for their persistence.
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Affiliation(s)
- Urszula Kosikowska
- From the Department of Pharmaceutical Microbiology With Laboratory for Microbiological Diagnostics, Medical University of Lublin (UK, IK-G, AM); Otoneurology Laboratory of III Chair of Pediatrics, Medical University of Lublin (AN), Lublin, Poland
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82
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Rodríguez MK, Agudelo CI, Duarte C. Aislamientos invasivos de Haemophilus influenzae en menores de 5 años: distribución de los serotipos y de la sensibilidad antimicrobiana, SIREVA II, Colombia 2002-2013. INFECTIO 2015. [DOI: 10.1016/j.infect.2014.12.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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83
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Desai S, Tsang R, St. Laurent M, Cox A. Collaboration on a public health-driven vaccine initiative. CANADA COMMUNICABLE DISEASE REPORT = RELEVE DES MALADIES TRANSMISSIBLES AU CANADA 2014; 40:365-368. [PMID: 29769865 PMCID: PMC5864475 DOI: 10.14745/ccdr.v40i17a04] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Disease surveillance can be used as an opportunity to determine priorities for research and the development of new therapeutics. This is evident in the work underway to develop a new vaccine to combat a serious invasive childhood disease: Haemophilus influenzae serotype a (Hia). Following the introduction of Hib vaccine into the routine childhood immunization schedule in Canada in the early 1990's, the Public Health Agency of Canada (PHAC) began to document the dropping rates of H influenzae serotype b (Hib) infection. However, invasive H. influenzae diseases due to non-Hib strains began to increase and in 2007, surveillance for invasive H. influenzae disease due to all serotypes as well as non-typeable strains was initiated. Current data suggests Hia is a cause of serious invasive disease, particularly in Aboriginal populations. Similar to Hib, Hia causes severe illnesses such as meningitis, sepsis and bacteremic pneumonia in young children under the age of five. Given the emerging threat due to Hia in Aboriginal populations in Canada, PHAC formed a partnership with the National Research Council of Canada (NRC) to investigate the potential of creating a capsular polysaccharide vaccine against Hia. At the present time, candidate vaccine seed strains have been identified and PHAC and the NRC are working with the Northern Ontario School of Medicine, the US Centers for Disease Control and Prevention and others. The goal of this research is to identify and prepare a candidate vaccine against Hia while increasing the understanding of how such a vaccine would improve the health of a vulnerable population.
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Affiliation(s)
- S Desai
- Center for Immunization and Respiratory Infectious Diseases, Public Health Agency of Canada, Ottawa, ON
| | - R Tsang
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB
| | - M St. Laurent
- Center for Immunization and Respiratory Infectious Diseases, Public Health Agency of Canada, Ottawa, ON
| | - A Cox
- Vaccine Program, Human Health Therapeutics, National Research Council of Canada, Ottawa, ON
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84
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Cerqueira AM, Tsang RSW, Jamieson FB, Ulanova M. A case of acute epiglottitis caused by Haemophilus influenzae type a in an adult. JMM Case Rep 2014. [DOI: 10.1099/jmmcr.0.001552] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
| | - Raymond S. W. Tsang
- Vaccine Preventable Bacterial Diseases, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Frances B. Jamieson
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Canada
- Public Health Laboratories, Public Health Ontario, Toronto, Ontario, Canada
| | - Marina Ulanova
- Northern Ontario School of Medicine, Thunder Bay, Ontario, Canada
- Lakehead University, Thunder Bay, Ontario, Canada
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85
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TSANG RSW, BRUCE MG, LEM M, BARRETO L, ULANOVA M. A review of invasive Haemophilus influenzae disease in the Indigenous populations of North America. Epidemiol Infect 2014; 142:1344-54. [PMID: 24598220 PMCID: PMC9151223 DOI: 10.1017/s0950268814000405] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 01/30/2014] [Accepted: 02/04/2014] [Indexed: 11/06/2022] Open
Abstract
Historically, the highest incidence rates of invasive Haemophilus influenzae disease in the world were found in North American and Australian Indigenous children. Although immunization against H. influenzae type b (Hib) led to a marked decrease in invasive Hib disease in countries where it was implemented, this disease has not been eliminated and its rates in Indigenous communities remain higher than in the general North American population. In this literature review, we examined the epidemiology of invasive H. influenzae disease in the pre-Hib vaccine era, effect of carriage on disease epidemiology, immune response to H. influenzae infection and Hib vaccination in Indigenous and Caucasian children, and the changing epidemiology after Hib conjugate vaccine has been in use for more than two decades in North America. We also explored reasons behind the continued high rates of invasive H. influenzae disease in Indigenous populations in North America. H. influenzae type a (Hia) has emerged as a significant cause of severe disease in North American Indigenous communities. More research is needed to define the genotypic diversity of Hia and the disease burden that it causes in order to determine if a Hia vaccine is required to protect the vulnerable populations.
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Affiliation(s)
- R. S. W. TSANG
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - M. G. BRUCE
- Arctic Investigations Program, Division of Preparedness and Emerging Infections, U.S. Centers for Disease Prevention and Control (CDC), Anchorage, AK, USA
| | - M. LEM
- Fraser Health Authority, Abbotsford, BC, Canada
| | - L. BARRETO
- Human Health Therapeutics Portfolio, National Research Council of Canada, Ottawa, ON, Canada
| | - M. ULANOVA
- Medical Sciences Division, Northern Ontario School of Medicine, Thunder Bay, ON, Canada
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86
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Shuel M, Whyte K, Drew T, Wylie J, Lefebvre B, Hoang L, Tsang RSW. Differential susceptibility of invasive Haemophilus influenzae serotype a and serotype b to ampicillin and other commonly prescribed antibiotics. Lett Appl Microbiol 2014; 59:193-9. [PMID: 24712310 DOI: 10.1111/lam.12265] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 04/03/2014] [Accepted: 04/03/2014] [Indexed: 12/17/2022]
Abstract
UNLABELLED Haemophilus influenzae serotype a (Hia) has become an important pathogen in the post-H. influenzae serotype b (Hib) vaccine era. Antibiotic resistance in H. influenzae is a global phenomenon, but few studies have looked at antibiotic resistance profiles with regard to serotype. Invasive Hia (n = 157), noninvasive Hia (n = 2) and invasive Hib (n = 42) collected over the last two decades from three Canadian Provinces were examined for resistance to several commonly prescribed antibiotics, and sequence types (STs) were determined by MLST. Only 1·9% of Hia showed antibiotic resistance, while 31% of Hib were resistant to one or more antibiotic. Resistance to ampicillin, sulfamethoxazole-trimethoprim, chloramphenicol and tetracycline was observed, with β-lactamase-mediated ampicillin resistance being the most common. Nine STs were identified for Hia with 7 STs belonging to the same clonal complex. Ten STs were observed in Hib strains, and all of them belonged to a single clonal complex. A possible correlation between sequence type and ampicillin resistance was observed for Hib, while no correlations were observed for Hia. SIGNIFICANCE AND IMPACT OF THE STUDY Despite H. influenzae serotype b (Hib) vaccine programs, invasive disease due to Hib still exists in Canada and is either second or third most common behind nontypeable and/or serotype a (Hia). Many previous studies on antibiotic resistance have focussed on respiratory isolates, and few have looked at resistance with regard to serotype. This study analysed antibiotic resistance in invasive Hia and Hib collected over 20 years from three provinces, and results found that significantly more Hib showed resistance compared to Hia. This provides a small snapshot of H. influenzae disease in Canada and highlights the importance to continually monitor antibiotic resistance profiles.
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Affiliation(s)
- M Shuel
- Vaccine Preventable Bacterial Diseases Division, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
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87
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Su YC, Resman F, Hörhold F, Riesbeck K. Comparative genomic analysis reveals distinct genotypic features of the emerging pathogen Haemophilus influenzae type f. BMC Genomics 2014; 15:38. [PMID: 24438474 PMCID: PMC3928620 DOI: 10.1186/1471-2164-15-38] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 01/09/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The incidence of invasive disease caused by encapsulated Haemophilus influenzae type f (Hif) has increased in the post-H. influenzae type b (Hib) vaccine era. We previously annotated the first complete Hif genome from a clinical isolate (KR494) that caused septic shock and necrotizing myositis. Here, the full genome of Hif KR494 was compared to sequenced reference strains Hib 10810, capsule type d (Hid) Rd Kw20, and finally nontypeable H. influenzae 3655. The goal was to identify possible genomic characteristics that may shed light upon the pathogenesis of Hif. RESULTS The Hif KR494 genome exhibited large regions of synteny with other H. influenzae, but also distinct genome rearrangements. A predicted Hif core genome of 1390 genes was shared with the reference strains, and 6 unique genomic regions comprising half of the 191 unique coding sequences were revealed. The majority of these regions were inserted genetic fragments, most likely derived from the closely-related Haemophilus spp. including H. aegyptius, H. haemolyticus and H. parainfluenzae. Importantly, the KR494 genome possessed several putative virulence genes that were distinct from non-type f strains. These included the sap2 operon, aef3 fimbriae, and genes for kanamycin nucleotidyltranserase, iron-utilization proteins, and putative YadA-like trimeric autotransporters that may increase the bacterial virulence. Furthermore, Hif KR494 lacked a hisABCDEFGH operon for de novo histidine biosynthesis, hmg locus for lipooligosaccharide biosynthesis and biofilm formation, the Haemophilus antibiotic resistance island and a Haemophilus secondary molybdate transport system. We confirmed the histidine auxotrophy and kanamycin resistance in Hif by functional experiments. Moreover, the pattern of unique or missing genes of Hif KR494 was similar in 20 Hif clinical isolates obtained from different years and geographical areas. A cross-species comparison revealed that the Hif genome shared more characteristics with H. aegyptius than Hid and NTHi. CONCLUSIONS The genomic comparative analyses facilitated identification of genotypic characteristics that may be related to the specific virulence of Hif. In relation to non-type f H. influenzae strains, the Hif genome contains differences in components involved in metabolism and survival that may contribute to its invasiveness.
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Affiliation(s)
| | | | | | - Kristian Riesbeck
- Medical Microbiology, Department of Laboratory Medicine Malmö, Lund University, Jan Waldenströms gata 59, SE-205 02 Malmö, Sweden.
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