Pneumococcal resistance to antibiotics

Convergent impact of vaccination and antibiotic pressures on pneumococcal populations

Streptococcus pneumoniae is a remarkably adaptable and successful human pathogen, playing dual roles of both asymptomatic carriage in the nasopharynx and invasive disease including pneumonia, bacteremia, and meningitis. Efficacious vaccines and effective antibiotic therapies are critical to mitigating morbidity and mortality. However, clinical interventions can be rapidly circumvented by the pneumococcus by its inherent proclivity for genetic exchange. This leads to an underappreciated interplay between vaccine and antibiotic pressures on pneumococcal populations. Circulating populations have undergone dramatic shifts due to the introduction of capsule-based vaccines of increasing valency imparting strong selective pressures. These alterations in population structure have concurrent consequences on the frequency of antibiotic resistance profiles in the population. This review will discuss the interactions of these two selective forces. Understanding and forecasting the drivers of antibiotic resistance and capsule switching are of critical importance for public health, particularly for such a genetically promiscuous pathogen as S. pneumoniae.

A review of penicillin binding protein and group A Streptococcus with reduced-β-lactam susceptibility

With the widespread use of antibiotics, antimicrobial resistance (AMR) has become a global problem that endangers public health. Despite the global high prevalence of group A Streptococcus (GAS) infections and the global widespread use of β-lactams, β-lactams remain the first-line treatment option for GAS infection. β-hemolytic streptococci maintain a persistent susceptibility to β-lactams, which is an extremely special phenomenon in the genus Streptococci, while the exact current mechanism is not known. In recent years, several studies have found that the gene encoding penicillin binding protein 2X (pbp2x) is associated with GAS with reduced-β-lactam susceptibility. The purpose of this review is to summarize the current published data on GAS penicillin binding proteins and β-lactam susceptibility, to explore the relationship between them, and to be alert to the emergence of GAS with reduced susceptibility to β-lactams.

Genetic determinants of macrolide and tetracycline resistance in penicillin non-susceptible Streptococcus pneumoniae isolates from people living with HIV in Dar es Salaam, Tanzania

BACKGROUND

Over one million yearly deaths are attributable to Streptococcus pneumoniae and people living with HIV are particularly vulnerable. Emerging penicillin non-susceptible Streptococcus pneumoniae (PNSP) challenges therapy of pneumococcal disease. The aim of this study was to determine the mechanisms of antibiotic resistance among PNSP isolates by next generation sequencing.

METHODS

We assessed 26 PNSP isolates obtained from the nasopharynx from 537 healthy human immunodeficiency virus (HIV) infected adults in Dar es Salaam, Tanzania, participating in the randomized clinical trial CoTrimResist (ClinicalTrials.gov identifier: NCT03087890, registered on 23rd March, 2017). Next generation whole genome sequencing on the Illumina platform was used to identify mechanisms of resistance to antibiotics among PNSP.

RESULTS

Fifty percent (13/26) of PNSP were resistant to erythromycin, of these 54% (7/13) and 46% (6/13) had MLS_B phenotype and M phenotype respectively. All erythromycin resistant PNSP carried macrolide resistance genes; six isolates had mef(A)-msr(D), five isolates had both erm(B) and mef(A)-msr(D) while two isolates carried erm(B) alone. Isolates harboring the erm(B) gene had increased MIC (> 256 µg/mL) towards macrolides, compared to isolates without erm(B) gene (MIC 4-12 µg/mL) p < 0.001. Using the European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines, the prevalence of azithromycin resistance was overestimated compared to genetic correlates. Tetracycline resistance was detected in 13/26 (50%) of PNSP and all the 13 isolates harbored the tet(M) gene. All isolates carrying the tet(M) gene and 11/13 isolates with macrolide resistance genes were associated with the mobile genetic element Tn6009 transposon family. Of 26 PNSP isolates, serotype 3 was the most common (6/26), and sequence type ST271 accounted for 15% (4/26). Serotypes 3 and 19 displayed high-level macrolide resistance and frequently carried both macrolide and tetracycline resistance genes.

CONCLUSION

The erm(B) and mef(A)-msr(D) were common genes conferring resistance to MLS_B in PNSP. Resistance to tetracycline was conferred by the tet(M) gene. Resistance genes were associated with the Tn6009 transposon.

A twenty years' results of the antimicrobial resistance profile and multidrug resistance trend of invasive Streptococcus pneumoniae isolates recovered from adult patients in Turkey: A literature review

PURPOSE

The aim of this study is to analyze antimicrobial resistance and multidrug (MDR)/extensively (XDR) resistance trend among Streptococcus pneumoniae isolates causing invasive disease in adult patients.

METHODS

We analyzed antimicrobial resistance and multidrug resistance trend among invasive S.pneumoniae isolates recovered from adult patients (≥18-years) in a tertiary University Hospital, Turkey between 1996 and 2018. The antibiotic susceptibility pattern was determined by using gradient-test for penicillin and cefotaxime and disk-diffusion method for other antibiotics.

RESULTS

A total of 272 isolates (74.3% from the bloodstream) of S. pneumoniae were collected during the study period. The highest non-susceptibility rate was obtained for tetracycline (63.5%), followed by trimethoprim/sulfamethoxazole (48%), penicillin-oral (30.4%), erythromycin (21.7%), clindamycin (15.8%), ciprofloxacin/levofloxacin (5.9%), penicillin-parenteral (5.5%), cefotaxime (2.2%), and rifampisin (1.8%), respectively. No resistance was observed against vancomycin during the years studied. Over the study period, a significant increase in the rate of antimicrobial resistance among invasive pneumococcal isolates was detected with a peak at period 2014-2018. Although there was an increase in the rates of non-susceptibility to penicillin oral, parenteral penicillin, cefotaxime, erythromycin and clindamycin in adult patients, the results were not statistically significant except erythromycin. Prevalence of MDR and XDR S. pneumoniae were 29% and 9.2% respectively. When the serotypes of MDR isolates were examined, it was noted that serotype 19F (35%) and 14 (12.5%) were the most common.

CONCLUSIONS

Our study showed an overall increase in non-susceptibility rates of penicillin and erythromycin in invasive S.pneumoniae isolates recovered from Turkish adult patients. Although the prevalence of MDR showed fluctuation between years, the incidence of MDR remained stable. These data indicate the necessity for continuous monitoring and assessment of serotypes and antimicrobial resistance trends in S.pneumoniae in different age groups at both the national and the regional levels as it can be affected by the serotypes dominant in that region, rational use of antibiotics and the vaccination programs.

Integrative Reverse Genetic Analysis Identifies Polymorphisms Contributing to Decreased Antimicrobial Agent Susceptibility in Streptococcus pyogenes

Identification of genetic polymorphisms causing increased antibiotic resistance in bacterial pathogens traditionally has proceeded from observed phenotype to defined mutant genotype. The availability of large collections of microbial genome sequences that lack antibiotic susceptibility metadata provides an important resource and opportunity to obtain new information about increased antimicrobial resistance by a reverse genotype-to-phenotype bioinformatic and experimental workflow. We analyzed 26,465 genome sequences of Streptococcus pyogenes, a human pathogen causing 700 million infections annually. The population genomic data identified amino acid changes in penicillin-binding proteins 1A, 1B, 2A, and 2X with signatures of evolution under positive selection as potential candidates for causing decreased susceptibility to β-lactam antibiotics. Construction and analysis of isogenic mutant strains containing individual amino acid replacements in penicillin-binding protein 2X (PBP2X) confirmed that the identified residues produced decreased susceptibility to penicillin. We also discovered the first chimeric PBP2X in S. pyogenes and show that strains containing it have significantly decreased β-lactam susceptibility. The novel integrative reverse genotype-to-phenotype strategy presented is broadly applicable to other pathogens and likely will lead to new knowledge about antimicrobial agent resistance, a massive public health problem worldwide. IMPORTANCE The recent demonstration that naturally occurring amino acid substitutions in Streptococcus pyogenes PBP2X are sufficient to cause severalfold reduced susceptibility to multiple β-lactam antibiotics in vitro raises the concern that these therapeutic agents may become compromised. Substitutions in PBP2X are common first-step mutations that, with the incremental accumulation of additional adaptive mutations within the PBPs, can result in high-level resistance. Because β-lactam susceptibility testing is not routinely performed, the nature and extent of such substitutions within the PBPs of S. pyogenes are poorly characterized. To address this knowledge deficit, polymorphisms in the PBPs were identified among the most comprehensive cohort of S. pyogenes genome sequences investigated to date. The mutational processes and selective forces acting on the PBPs were assessed to identify specific substitutions likely to influence β-lactam susceptibility and to evaluate factors posited to be impediments to resistance emergence.

Hospital-based sentinel surveillance for bacterial meningitis in under-five children prior to the introduction of the PCV13 in India

INTRODUCTION

A hospital-based sentinel surveillance network for bacterial meningitis was established in India to estimate the burden of bacterial meningitis, and the proportion of major vaccine-preventable causative organisms. This report summarises the findings of the surveillance conducted between March 2012, and September 2016 in eleven hospitals.

METHODS

We enrolled eligible children with bacterial meningitis in the age group of one to 59 months. CSF samples were collected and processed for biochemistry, culture, latex agglutination, and real-time PCR. Pneumococcal isolates were serotyped and tested for antimicrobial susceptibility.

RESULTS

Among 12 941 enrolled suspected meningitis cases, 586 (4.5%) were laboratory confirmed. S. pneumoniae (74.2%) was the most commonly detected pathogen, followed by H. influenzae (22.2%), and N. meningitidis (3.6%). Overall 58.1% of confirmed bacterial meningitis cases were children aged between one, and 11 months. H. influenzae meningitis cases had a high (12.3%) case fatality rate. The serotypes covered in PCV13 caused 72% pneumococcal infections, and the most common serotypes were 14 (18.3%), 6B (12.7%) and 19F (9.9%). Non-susceptibility to penicillin was 57%. Forty-five (43.7%) isolates exhibited multidrug resistance, of which 37 were PCV13 serotype isolates.

CONCLUSIONS

The results are representative of the burden of bacterial meningitis among under-five children in India. The findings were useful in rolling out PCV in the National Immunization Program. The non-susceptibility to penicillin and multidrug resistance was an important observation. Timely expansion of PCV across India will significantly reduce the burden of antimicrobial resistance. Continued surveillance is needed to understand the trend after PCV expansion in India.

Phenotypic and Molecular Characterization of Penicillin and Macrolide-Resistant Streptococcus pneumoniae Serotypes Among Pediatric Patients in Addis Ababa, Ethiopia

Background

In several countries, introduction of the pneumococcal conjugate vaccine (PCV) has led to a decline in antimicrobial-resistant pneumococcal disease but has also resulted in a concomitant increase in antimicrobial-resistant, non-vaccine serotypes of Streptococcus pneumoniae. We sought to determine the magnitude of penicillin and macrolide resistance among pneumococcal serotypes and the mechanisms of macrolide resistance in Ethiopia, 5 years after the introduction of PCV10 in the country.

Methods

Susceptibility to penicillin and erythromycin of 119 pneumococcal isolates collected from pediatric patients aged 0-15 years in Addis Ababa, Ethiopia, was tested using disc diffusion, and minimum inhibitory concentration (MIC) was also determined by Etest. Pneumococcal serotypes were determined by sequencing the cpsB gene and using Quellung reaction. Polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism analysis were used to detect and differentiate the macrolide resistance genes erm(B), mef(A), and mef(B).

Results

Among the 119 isolates, 2.5% (3/119) were resistant to penicillin, while 58% (69/119) were intermediate. Resistance to erythromycin was observed in 33.6% (40/119) of the isolates with the highest level of resistance among isolates from middle ear discharge, i.e., 53.3% (8/15). Half (19/40) of the erythromycin resistant isolates were serotype 19A and among serotype 19A isolates, the majority i.e., 54.3% (19/35) were resistant to erythromycin. The most common macrolide resistance determinant was mef(E) with a prevalence of 50% (20/40).

Conclusion

Five years after introduction of PCV10 in Ethiopia, we observed that the prevalence of penicillin-resistant S. pneumoniae was low. However, there was a high level of macrolide resistance which was mostly in serotype 19A, and the resistance was mainly mediated by efflux pumps. Introduction of PCV13 (which covers serotype 19A) would significantly improve coverage of the macrolide-resistant serotypes. Continued surveillance of pneumococcal serotype distribution and their antibiotic resistance pattern in Ethiopia is warranted.

Discerning perturbed assembly of lipids in a model membrane in presence of violacein

Violacein is a naturally found pigment that is used by some gram negative bacteria to defend themselves from various gram positive bacteria. As a result, this molecule has caught attention for its potential biomedical applications and has already shown promising outcomes as an antiviral, an antibacterial, and an anti-tumor agent. Understanding the interaction of this molecule with a cellular membrane is an essential step to extend its use in the pharmaceutical paradigm. Here, the interaction of violacein with a lipid monolayer formed at the air-water interface is found to depend on electrostatic nature of lipids. In presence of violacein, the two dimensional (2D) pressure-area isotherms of lipids have exhibited changes in their phase transition pressure and in-plane elasticity. To gain insights into the out-of-plane structural organization of lipids in a membrane, X-ray reflectivity (XRR) study on a solid supported lipid monolayer on a hydrophilic substrate has been performed. It has revealed that the increase in membrane thickness is more pronounced in the zwitterionic and positively charged lipids compared to the negatively charged one. Further, the lipid molecules are observed to decrease their tilt angle made with the normal of lipid membrane along with an alteration in their in-plane ordering. This has been quantified by grazing incidence X-ray diffraction (GIXD) experiments on the multilayer membrane formed in an environment with controlled humidity. The structural reorganization of lipid molecules in presence of violacein can be utilized to provide a detailed mechanism of the interaction of this molecule with cellular membrane.

Prevalence and Antimicrobial Susceptibility of Streptococcus pneumoniae Isolated from Clinical Samples in the Past 8 Years in Korea

Pneumococcal infection is the main causative agent of pneumonia, meningitis, and sepsis in immunocompromised and elderly people. The samples in this study were collected from subjects in an 800-bed hospital in Chungnam province, Korea, over the past 8 years. Of the 473,230 samples obtained for microbial culture from 2012 to 2019, Streptococcus pneumoniae was isolated from 714 samples collected from 702 patients, with a pneumococcal-positive rate of 0.15%. We investigated the temporal, demographic, and specimen-specific distributions, as well as the antibiotic susceptibility pattern for S. pneumonia. The age of patients ranged from 0 days to 98 years, with an average age of 64.7 years. The distribution among the sexes was 2.4 : 1 (male : female), with more samples isolated from male patients. We observed that spring was the predominant season in which the infection occurred, accounting for 37.6% of the cases. Pneumococci were most frequently isolated from sputum (608 cases, 85.2%). Invasive infections were detected at a rate of 66% (in blood cultures), and noninvasive infections were detected at a rate of 91% (in sputum cultures). Antimicrobial resistance to ceftriaxone, cefotaxime, erythromycin, tetracycline, clindamycin, cotrimoxazole, levofloxacin, and penicillin, based on noninvasive infections, was observed in 21.6%, 27.2%, 79.2%, 73.2%, 68.0%, 51.3%, 9.8%, and 18.1% of cases, respectively. Additionally, on average, 66.9% of multidrug-resistant bacteria showed resistance to three or more antimicrobial agents, and 2.8% showed resistance to all other antibacterial agents except vancomycin. These results might facilitate the administration of appropriate empirical antibacterial therapy for pneumococcal infections.

Serotype Distribution and Antimicrobial Susceptibility of Streptococcus pneumoniae in Pre- and Post- PCV7/13 Eras, Taiwan, 2002-2018

In Taiwan, the 7-valent pneumococcal conjugate vaccine (PCV7) was introduced in 2006 and a PCV13 national childhood catchup program was implemented in 2013. To delineate the trend of serotype distribution and antimicrobial susceptibility following vaccination programs, we investigated a total of 1845 Streptococcus pneumoniae isolates collected biennially between 2002 and 2018 over a 3-month period from 25 hospitals. The number of isolates collected over the years decreased significantly in all age groups, from a total of 320 isolates in 2002 (pre-PCV), to 196 in 2010 (post-PCV7/pre-PCV13), to 89 in 2018 (post-PCV13). Overall, PCV7/PCV13 serotypes comprised 66.9%/76.3%, 53.1%/78.1%, and 15.7%/31.5% of isolates in 2002, 2010, and 2018, respectively. The leading serotypes in the pre-PCV era were 23F, 19F, 6B, and 14, while serotype 19A predominated in the post-PCV7/pre-PCV13 era, but non-vaccine serotypes (NVT) 15A (18.0%) and 23A (15.7%) surpassed 19A (10.1%) to become the top two leading serotypes in 2018. All the major serotypes, including the emergent serotypes 15A and 23A, were multidrug-resistant with high rates of non-susceptibility to β-lactam (except serotype 3) and several non-β-lactam agents. PFGE and MLST revealed that while meropenem-susceptible serotype 15A-ST3058 isolates and a serotype 23A-ST338 clone existed in earlier years, rise and spread of meropenem-non-susceptible serotype 15A-ST63 and serotype 23A-ST166 clones occurred in recent years. We conclude that successive implementation of PCVs has led to a marked decrease in pneumococcal isolate burden, but the replacement by meropenem-non-susceptible NVT 15A and 23A highlights the need for continued local surveillance to track pneumococcal evolution in each region to help vaccine polyvalency decisions.

Invasive pneumococcal disease in hospitalised children from Lima, Peru before and after introduction of the 7-valent conjugated vaccine

The objective of this study was to determine the serotype distribution and antibiotic resistance of invasive pneumococcal disease (IPD) strains in children from Lima, Peru, before and after the introduction of the 7-valent pneumococcal conjugate vaccine (PCV7), which was introduced in the national immunisation program on 2009. We conducted a prospective, multicentre, passive surveillance IPD study during 2006-2008 and 2009-2011, before and right after the introduction of PCV7 in Peru. The study was performed in 11 hospitals and five private laboratories in Lima, Peru, in patients &lt;18 years old, with sterile site cultures yielding Streptococcus pneumoniae. In total 159 S. pneumoniae isolates were recovered. There was a decrease in the incidence of IPD in children &lt;2 years old after the introduction of PCV7 (18.4/100 000 vs. 5.1/100 000, P = 0.004). Meningitis cases decreased significantly in the second period (P = 0.036) as well as the overall case fatality rate (P = 0.025), including a decreased case fatality rate of pneumonia (16.3% to 0%, P = 0.04). PCV7 serotypes showed a downward trend. Vaccine-preventable serotypes caused 78.9% of IPD cases, mainly 14, 6B, 5, 19F and 23F. A non-significant increase in erythromycin resistance was reported. Our findings suggest that the introduction of PCV7 led to a significant decrease of IPD in children under 2 years old and in the overall case fatality rate.

Development of Streptococcus pneumoniae Pan-Group Quorum-Sensing Modulators

The rapid increase in multidrug-resistant pathogens is a major health concern that could bring mankind back to the pre-antibiotic era. Streptococcus pneumoniae is a highly recombinogenic opportunistic pathogen that causes a variety of deadly diseases and rapidly develops resistance to current antibiotic treatments. S. pneumoniae pathogenicity is dependent on a cell-density communication mechanism, or quorum sensing (QS), termed the competence regulon. In this work, we set out to design signal-based QS modulators capable of affecting the two specificity groups found in S. pneumoniae. Through systematic analysis and rational design, we were able to construct peptide-based pan-group QS activators and inhibitors with activities in the nanomolar range. These novel analogues are privileged scaffolds for the development of anti-virulence therapeutics against S. pneumoniae infections.

Serotype Distribution and Antimicrobial Resistance of Invasive and Noninvasive Streptococcus pneumoniae Isolates in Korea between 2014 and 2016

Background

Several factors contribute to differences in Streptococcus pneumoniae serotype distribution. We investigated the serotype distribution and antimicrobial resistance of S. pneumoniae isolated between 2014 and 2016 in Korea.

Methods

We collected a total of 1,855 S. pneumoniae isolates from 44 hospitals between May 2014 and May 2016, and analyzed the serotypes by sequential multiplex PCR. We investigated the distribution of each serotype by patient age, source of the clinical specimen, and antimicrobial resistance pattern.

Results

The most common serotypes were 11A (10.1%), followed by 19A (8.8%), 3 (8.5%), 34 (8.1%), 23A (7.3%), and 35B (6.2%). The major invasive serotypes were 3 (12.6%), 19A (7.8%), 34 (7.8%), 10A (6.8%), and 11A (6.8%). Serotypes 10A, 15B, 19A, and 12F were more common in patients ≤5 years old, while serotype 3 was more common in patients ≥65 years old compared with the other age groups. The coverage rates of pneumococcal conjugate vaccine (PCV)7, PCV10, PCV13, and pneumococcal polysaccharide vaccine 23 were 11.8%, 12.12%, 33.3%, and 53.6%, respectively. Of the 1,855 isolates, 857 (46.2%) were multi-drug resistant (MDR), with serotypes 11A and 19A predominant among the MDR strains. The resistance rates against penicillin, cefotaxime, and levofloxacin were 22.8%, 12.5%, and 9.4%, respectively.

Conclusions

There were significant changes in the major S. pneumoniae serotypes in the community. Non-PCV13 serotypes increased in patients ≤5 years old following the introduction of national immunization programs with the 10- and 13-polyvalent vaccines.

Synergistic Antimicrobial Effects of Cefabronchin®

Antibiotic resistance of Streptococcus pneumoniae has risen to worrying levels in the past few decades worldwide, and subsequently, effective treatment of respiratory tract infections has become even more challenging. While the need to develop new strategies to combat bacterial infections is urgent, novel antibiotic compounds are no longer a priority of the pharmaceutical industry. However, resistance-modifying agents can alleviate the spread of antibiotic resistance and render existing antibiotics effective again. In the present study, we aimed to determine the combinatory antimicrobial effects of the commercial herbal product Cefabronchin^® and antibiotic compounds, such as amoxicillin and clarithromycin, on 6 clinical isolates of S. pneumoniae. Therefore, the minimal inhibitory concentration (MIC) of each agent before and after adding Cefabronchin^® at different concentrations was determined by applying the checkerboard method. Sub-inhibitory concentrations of the added Cefabronchin^® were found to reduce the MIC down to between 3.4% and 29.2% of the amoxicillin MIC and down to between 10.4% and 45.8% of the clarithromycin MIC in all 6 strains. In conclusion, this study provides evidence for the improved antimicrobial effects of commonly used antibiotics in combination with Cefabronchin^® in order to combat infections with antibiotic-resistant S. pneumoniae strains.

Impact of existing vaccines in reducing antibiotic resistance: Primary and secondary effects

Vaccines impact antibiotic-resistant infections in two ways: through a direct reduction in the organisms and strains carrying resistant genes that are specifically targeted by the vaccine and also via a secondary effect through a reduction in febrile illnesses that often lead to the use of antibiotics. We review here the impact of pneumococcal conjugate vaccines (PCVs) on the prevalence of antibiotic-resistant disease and antibiotic usage as an example of the direct effect of vaccines on antibiotic resistance and the impact of influenza vaccination on antibiotic usage as an example of a secondary effect. A prelicensure study of a PCV in Africa demonstrated 67% fewer penicillin-resistant invasive disease episodes in the PCV group compared with controls. Similar studies in the United States and Europe demonstrated reductions in antibiotic use consistent with the vaccines' impact on the risk of otitis media infections in children. Postlicensure reductions in the circulation of antibiotic-resistant strains targeted by the vaccines have been dramatic, with virtual elimination of these strains in children following vaccine introduction. In terms of a secondary effect, following influenza vaccination reductions of 13-50% have been observed in the use of antibiotics by individuals receiving influenza vaccine compared with controls. With the demonstrated effectiveness of vaccination programs in impacting the risk of antibiotic-resistant infections and the increasing threat to public health that these infections represent, more attention needs to be given to development and utilization of vaccines to address antibiotic resistance.

Magnoflorine Ameliorates Lipopolysaccharide-Induced Acute Lung Injury via Suppressing NF-κB and MAPK Activation

Acute lung injury (ALI) which is featured by a strong pulmonary inflammation, is a major cause of morbidity and mortality in critically ill patients. Magnoflorine, a quaternary alkaloid isolated from Chinese herb Magnolia or Aristolochia, has been reported to have potent anti-inflammatory properties. However, the effect of magnoflorine on lipopolysaccharide (LPS)-induced ALI in mice has not been reported. The purpose of the present study is to investigate the anti-inflammatory effect of magnoflorine on LPS-induced ALI and elucidate its possible molecular mechanisms in RAW264.7 cells. The results of histopathological changes as well as the myeloperoxidase (MPO) activity indicated that magnoflorine significantly alleviated the lung injury induced by LPS. In addition, qPCR results showed that magnoflorine dose-dependently decreased the expression of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6. Immunofluorescence assay also confirmed that the level of Toll-like receptor 4 (TLR4) induced by LPS was inhibited by magnoflorine treatment. Further experiments were performed using Western blotting to detect the expression of related proteins in the NF-κB and MAPK signaling pathways. The results showed that magnoflorine suppressed the levels of phosphorylated p65, IκBα, p38, ERK, and JNK. In conclusion, all data indicate that magnoflorine could protect against LPS-induced inflammation in ALI at least partially by inhibiting TLR4-mediated NF-κB and MAPK signaling pathways.

Genome Sequencing Reveals a Large and Diverse Repertoire of Antimicrobial Peptides

Competition among bacterial members of the same ecological niche is mediated by bacteriocins: antimicrobial peptides produced by bacterial species to kill other bacteria. Bacteriocins are also promising candidates for novel antimicrobials. Streptococcus pneumoniae (the “pneumococcus”) is a leading cause of morbidity and mortality worldwide and a frequent colonizer of the human nasopharynx. Here, 14 newly discovered bacteriocin gene clusters were identified among >6,200 pneumococcal genomes. The molecular epidemiology of the bacteriocin clusters was investigated using a large global and historical pneumococcal dataset dating from 1916. These analyses revealed extraordinary bacteriocin diversity among pneumococci and the majority of bacteriocin clusters were also found in other streptococcal species. Genomic hotspots for the integration of different bacteriocin gene clusters were discovered. Experimentally, bacteriocin genes were transcriptionally active when the pneumococcus was under stress and when two strains were co-cultured in broth. These findings reveal much more diversity among bacterial defense mechanisms than previously appreciated, which fundamentally broaden our understanding of bacteriocins relative to intraspecies and interspecies nasopharyngeal competition and bacterial population structure.

Streptococcus pneumoniae Serotypes 9 and 14 Circulating in Brazil over a 23-Year Period Prior to Introduction of the 10-Valent Pneumococcal Conjugate Vaccine: Role of International Clones in the Evolution of Antimicrobial Resistance and Description of a Novel Genotype

Antimicrobial-resistant pneumococcal strains have been detected worldwide since the 1960s. In Brazil, the first penicillin-nonsusceptible pneumococci (PNSP) were reported in the 1980s, and their emergence and dissemination have been mainly attributed to serogroup 9 and serotype 14 strains, especially those highly related to recognized international clones. In the present study, antimicrobial susceptibility testing and multilocus sequence typing were performed on 315 pneumococcal isolates belonging to serogroup 9 (n = 99) or serotype 14 (n = 216), recovered from patients or asymptomatic carriers between 1988 and 2011 in Brazil, in order to trace changes in antimicrobial resistance and genotypes prior to the full introduction of the pneumococcal conjugate vaccine in the country. Over the 23-year study period, the PNSP levels increased, and four clonal complexes (CC156, CC66, CC15, and CC5401) have played important roles in the evolution and dissemination of pneumococcal isolates belonging to serogroup 9 and serotype 14, as well as in the emergence of antimicrobial resistance, in the pre-pneumococcal-vaccination era. The earliest PNSP strains detected in this study belonged to serotype 9N/ST66 and were single locus variants of the international clone Tennessee¹⁴-18 ST67 (CC66). The first serotype 14 PNSP isolates were identified in 1990 and were related to the England¹⁴-9 ST9 (CC15) clone. Serotype 14 PNSP variants of the Spain^9V-3 ST156 clone with elevated penicillin MICs and nonsusceptibility to other beta-lactams were detected in 1995 and showed an increasing trend over the years. The results also indicated that introduction of ST156 in our region was preceded by the emergence of trimethoprim-sulfamethoxazole resistance and by the dissemination of ST162. In addition to the presence of successful international clones, a novel regional serotype 14 genotype (CC5401) has emerged in 1996.

MLVA Typing of Streptococcus pneumoniae Isolates with Emphasis on Serotypes 14, 9N and 9V: Comparison of Previously Described Panels and Proposal of a Novel 7 VNTR Loci-Based Simplified Scheme

Streptococcus pneumoniae remains as an important cause of community-acquired bacterial infections, and the nasopharynx of asymptomatic carriers is the major reservoir of this microorganism. Pneumococcal strains of serotype 14 and serogroup 9 are among the most frequently isolated from both asymptomatic carriers and patients with invasive disease living in Brazil. Internationally disseminated clones belonging to such serotypes have been associated with the emergence and spread of antimicrobial resistance in our setting, highlighting the need for epidemiological tracking of these isolates. In this scenario, Multiple Loci VNTR Analysis (MLVA) has emerged as an alternative tool for the molecular characterization of pneumococci, in addition to more traditional techniques such as Multi-Locus Sequence Typing (MLST) and Pulsed-Field Gel Electrophoresis (PFGE). In the present study, 18 VNTR loci, as well as other previously described reduced MLVA panels (7 VNTR loci), were evaluated as tools to characterize pneumococcal strains of serotypes 14, 9N and 9V belonging to international and regional clones isolated in Brazil. The 18 VNTR loci panel was highly congruent with MLST and PFGE, being also useful for indicating the genetic relationship with international clones and for discriminating among strains with indistinguishable STs and PFGE profiles. Analysis of the results also allowed deducing a novel shorter 7 VNTR loci panel, keeping a high discriminatory power for isolates of the serotypes investigated and a high congruence level with MLST and PFGE. The newly proposed simplified panel was then evaluated for typing pneumococcal strains of other commonly isolated serotypes. The results indicate that MLVA is a faster and easier to perform, reliable approach for the molecular characterization of S. pneumoniae isolates, with potential for cost-effective application, especially in resource-limited countries.

Biological and Epidemiological Features of Antibiotic-Resistant Streptococcus pneumoniae in Pre- and Post-Conjugate Vaccine Eras: a United States Perspective

Streptococcus pneumoniae inflicts a huge disease burden as the leading cause of community-acquired pneumonia and meningitis. Soon after mainstream antibiotic usage, multiresistant pneumococcal clones emerged and disseminated worldwide. Resistant clones are generated through adaptation to antibiotic pressures imposed while naturally residing within the human upper respiratory tract. Here, a huge array of related commensal streptococcal strains transfers core genomic and accessory resistance determinants to the highly transformable pneumococcus. β-Lactam resistance is the hallmark of pneumococcal adaptability, requiring multiple independent recombination events that are traceable to nonpneumococcal origins and stably perpetuated in multiresistant clonal complexes. Pneumococcal strains with elevated MICs of β-lactams are most often resistant to additional antibiotics. Basic underlying mechanisms of most pneumococcal resistances have been identified, although new insights that increase our understanding are continually provided. Although all pneumococcal infections can be successfully treated with antibiotics, the available choices are limited for some strains. Invasive pneumococcal disease data compiled during 1998 to 2013 through the population-based Active Bacterial Core surveillance program (U.S. population base of 30,600,000) demonstrate that targeting prevalent capsular serotypes with conjugate vaccines (7-valent and 13-valent vaccines implemented in 2000 and 2010, respectively) is extremely effective in reducing resistant infections. Nonetheless, resistant non-vaccine-serotype clones continue to emerge and expand.

Serotype Distribution and Antimicrobial Resistance of Streptococcus pneumoniae Isolates Causing Invasive and Noninvasive Pneumococcal Diseases in Korea from 2008 to 2014

Introduction. Streptococcus pneumoniae is an important pathogen with high morbidity and mortality rates. The aim of this study was to evaluate the distribution of common serotypes and antimicrobial susceptibility of S. pneumoniae in Korea. Methods. A total of 378 pneumococcal isolates were collected from 2008 through 2014. We analyzed the serotype and antimicrobial susceptibility for both invasive and noninvasive isolates. Results. Over the 7 years, 3 (13.5%), 35 (10.8%), 19A (9.0%), 19F (6.6%), 6A (6.1%), and 34 (5.6%) were common serotypes/serogroups. The vaccine coverage rates of PCV7, PCV10, PCV13, and PPSV23 were 21.4%, 23.3%, 51.9%, and 62.4% in all periods. The proportions of serotypes 19A and 19F decreased and nonvaccine serotypes increased between 2008 and 2010 and 2011 and 2014. Of 378 S. pneumoniae isolates, 131 (34.7%) were multidrug resistant (MDR) and serotypes 19A and 19F were predominant. The resistance rate to levofloxacin was significantly increased (7.2%). Conclusion. We found changes of pneumococcal serotype and antimicrobial susceptibility during the 7 years after introduction of the first pneumococcal vaccine. It is important to continuously monitor pneumococcal serotypes and their susceptibilities.

Targeted synthesis of novel β-lactam antibiotics by laccase-catalyzed reaction of aromatic substrates selected by pre-testing for their antimicrobial and cytotoxic activity

The rapidly increasing problem of antimicrobial-drug resistance requires the development of new antimicrobial agents. The laccase-catalyzed amination of dihydroxy aromatics is a new and promising method to enlarge the range of currently available antibiotics. Thirty-eight potential 1,2- and 1,4-hydroquinoid laccase substrates were screened for their antibacterial and cytotoxic activity to select the best substrates for laccase-catalyzed coupling reaction resulting in potent antibacterial derivatives. As a result, methyl-1,4-hydroquinone and 2,3-dimethyl-1,4-hydroquinone were used as parent compounds and 14 novel cephalosporins, penicillins, and carbacephems were synthesized by amination with amino-β-lactam structures. All purified products were stable in aqueous buffer and resistant to the action of β-lactamases, and in agar diffusion and broth micro-dilution assays, they inhibited the growth of several Gram-positive bacterial strains including multidrug-resistant Staphylococcus aureus and Enterococci. Their in vivo activity and cytotoxicity in a Staphylococcus-infected, immune-suppressed mouse model are discussed.

High Throughput Screen Identifies Natural Product Inhibitor of Phenylalanyl-tRNA Synthetase from Pseudomonas aeruginosa and Streptococcus pneumoniae

Pseudomonas aeruginosa and Streptococcus pneumoniae are causative agents in a wide range of infections. Genes encoding proteins corresponding to phenylalanyl-tRNA synthetase (PheRS) were cloned from both bacteria. The two forms of PheRS were kinetically evaluated and the K(m)'s for P. aeruginosa PheRS with its three substrates, phenylalanine, ATP and tRNA(Phe) were determined to be 48, 200, and 1.2 µM, respectively, while the K(m)'s for S. pneumoniae PheRS with respect to phenylalanine, ATP and tRNA(Phe) were 21, 225 and 0.94 µM, respectively. P. aeruginosa and S. pneumoniae PheRS were used to screen a natural compound library and a single compound was identified that inhibited the function of both enzymes. The compound inhibited P. aeruginosa and S. pneumoniae PheRS with IC50's of 2.3 and 4.9 µM, respectively. The compound had a K(I) of 0.83 and 0.98 µM against P. aeruginosa and S. pneumoniae PheRS, respectively. The minimum inhibitory concentration (MIC) of the compound was determined against a panel of Gram positive and negative bacteria including efflux pump mutants and hyper-sensitive strains. MICs against wild-type P. aeruginosa and S. pneumoniae cells in culture were determined to be 16 and 32 µg/ml, respectively. The mechanism of action of the compound was determined to be competitive with the amino acid, phenylalanine, and uncompetitive with ATP. There was no inhibition of cytoplasmic protein synthesis, however, partial inhibition of the human mitochondrial PheRS was observed.

Discovery of novel pneumococcal surface antigen A (PsaA) inhibitors using a fragment-based drug design approach

Streptococcus pneumoniae is a leading cause of life-threatening bacterial infections, especially in young children in developing countries. Pneumococcal infections can be treated with β-lactam antibiotics, but rapid emergence of multidrug-resistant strains of S. pneumoniae over the past two decades has emphasized the need to identify novel drug targets. Pneumococcal surface antigen A (PsaA) is one such target, found on the cell surface of S. pneumoniae. It functions as a high-affinity substrate-binding protein, facilitating acquisition of Mn(2+), which has an important role in protecting S. pneumoniae from reactive oxygen species and, hence, oxidative stress. Consequently, PsaA is essential for bacterial survival and an important virulence factor, which makes it a promising target for antibiotic drug development. To design novel PsaA inhibitors, we used a combination of de novo fragment-based drug discovery and in silico virtual screening methods. We profiled a collection of low molecular weight compounds that were selected based on their structural diversity and ability to bind to apo-PsaA in a virtual docking experiment. The screening resulted in two initial hits that were further optimized by structural variation to improve their potency while maintaining their ligand efficiency and favorable physicochemical properties. The optimized hits were validated using a cell-based assay and molecular dynamics simulations. We found that virtual screening substantially augmented fragment-based drug design approaches, leading to the identification of novel pneumococcal PsaA inhibitors.

High-yield production of a functional bacteriophage lysin with antipneumococcal activity using a plant virus-based expression system

Streptococcus pneumoniae is the causative agent of several serious infectious diseases. It is becoming increasingly antibiotic resistant worldwide, and thus new antimicrobials are needed. One alternative to antibiotics may be the use of peptidoglycan hydrolases, the bacteriophage lytic enzymes. In this study, we demonstrated high level expression of the S. pneumoniae bacteriophage lysin Pal in Nicotiana benthamiana - TMV (Tobacco Mosaic Virus) transient expression system. The protein was purified to homogeneity and tested for streptococci killing activity in vitro and in vivo. In vitro, Pal was able to lyse three tested S. pneumoniae strains: NCTC12695, NCTC12977 and NCTC11888. The treatment of BALB/c mice with 100 μg, 200 μg and 400 μg of Pal 1h post-challenge with double lethal dose of S. pneumoniae NCTC12695 strain showed a clear dose response and protected from lethal sepsis 30%, 40% and 50% of mice, respectively. The improved mice survival correlated with decreased blood bacterial titers. In conclusion, these results suggest that plant-expressed bacteriophage lysins may have potential use as antimicrobial agents.

Antimicrobial Susceptibility Pattern of Invasive Pneumococcal Isolates in North West Nigeria

BACKGROUND

An alarming increase in infections due to penicillin non-susceptible pneumococci (PNSP) has been documented in nearly all countries. Increasingly, PNSP are also resistant to other antibiotics, and a growing number of clinical failures following the use of these agents have been reported.

AIMS

To determine the resistance pattern of pneumococcal isolates from patients with invasive pneumococcal infection in North West Nigeria.

MATERIALS AND METHODS

In a cross-sectional study clinical specimens were obtained from patients with community acquired pneumonia (CAP), meningitis and bacteraemia over a 2 year period. Pneumococcus strains were identified. Isolates were tested against a panel of antibiotics using E-test strips, and interpreted according to the CLSI criteria. 0.06 μg/ml was used as break point for penicillin. Analysis was carried out using descriptive statistics; relationships determined using chi-squared or Fisher's exact tests, with P < 0.05 regarded as significant.

RESULTS

Total number of isolates was 132. Twenty-two (16.7%) of the isolates were fully sensitive to penicillin while 73 (55.3%) and 37 (28.0%) were intermediately and fully resistant, respectively. One hundred and twenty-seven (96.2%) of the isolates were fully resistant to trimethoprim-sulphamethoxazole. Eleven (8.5%) were fully resistant to amoxicillin and 104 (78.8%) and 17 (12.9%) were intermediately resistant and fully susceptible. One hundred and six (80.3%) of the isolates were fully susceptible to chloramphenicol. Resistance to penicillin was shown to infer resistance to other antibiotics.

CONCLUSIONS

Pneumococcal resistance is common in North West Nigeria. Ceftriaxone retains excellent activity against most of the invasive isolate, while trimethoprim-sulphamethoxazole is almost uniformly resistant.

Antibacterial resistance in sub-Saharan Africa: an underestimated emergency

Antibacterial resistance-associated infections are known to increase morbidity, mortality, and cost of treatment, and to potentially put others in the community at higher risk of infections. In high-income countries, where the burden of infectious diseases is relatively modest, resistance to first-line antibacterial agents is usually overcome by use of second- and third-line agents. However, in developing countries where the burden of infectious diseases is high, patients with antibacterial-resistant infections may be unable to obtain or afford effective second-line treatments. In sub-Saharan Africa (SSA), the situation is aggravated by poor hygiene, unreliable water supplies, civil conflicts, and increasing numbers of immunocompromised people, such as those with HIV, which facilitate both the evolution of resistant pathogens and their rapid spread in the community. Because of limited capacity for disease detection and surveillance, the burden of illnesses due to treatable bacterial infections, their specific etiologies, and the awareness of antibacterial resistance are less well established in most of SSA, and therefore the ability to mitigate their consequences is significantly limited.

Betulin protects mice from bacterial pneumonia and acute lung injury

Betulin, a naturally occurring triterpene, has shown anti-HIV activity, but details on the anti-inflammatory activity are scanty. In this study, we sought to investigate the effect of Betulin on LPS-induced activation of cell lines with relevance for lung inflammation in vitro and on lung inflammation elicited by either LPS or viable Escherichia coli (E. coli) in vivo. In vitro, Betulin inhibited LPS-induced tumor necrosis factor α (TNF-α) and (interleukin) IL-6 levels and up-regulated the level of IL-10. Also Betulin suppressed the phosphorylation of nuclear factor-κB (NF-κB) p65 protein in LPS-stimulated RAW 264.7 cells. In vivo, Betulin alleviated LPS-induced acute lung injury. Treatment with Betulin diminished pro-inflammatory cytokines, myeloperoxidase activity and bacterial loads in lung tissue during gram-negative pneumonia. Our findings demonstrated that Betulin inhibits pro-inflammatory responses induced by the gram-negative stimuli LPS and E. coli, suggesting that Betulin may represent a novel strategy for the treatment of lung inflammation.

Serotype distribution and susceptibility to penicillin and erythromycin among noninvasive or colonization isolates of Streptococcus pneumoniae in northern Japan: a cross-sectional study in the pre-PCV7 routine immunization period

Distribution of serotypes, prevalence of resistance to penicillin and/or erythromycin (EM), and its genetic traits were analyzed for a total of 1,061 noninvasive or colonization isolates of Streptococcus pneumoniae (998 and 61 isolates from children and adults, respectively) in Hokkaido, northern main island of Japan, in the year 2011, the pre-PCV7 routine immunization period. Serotype deduction was performed by sequential multiplex polymerase chain reaction (PCR), employing mutagenic PCR-restriction fragment length polymorphism for discrimination of 6A/C and 6B/D. Unaltered three PBP genes and macrolide resistance genes erm(B) and mef(A/E) were detected by multiplex PCR. Among isolates from children, 25 serotypes, including the prevalent types 6B (17.5%), 19F (15.6%), 23F (12.2%), and 6C (11.6%), were identified, revealing the PCV7 and PCV13 coverage rates as 48.2% and 60.3%, respectively, while serotype 3 was the most frequent (19.0%) among isolates from adults. Most of the pediatric isolates (96.8%) exhibited resistance to EM (minimum inhibitory concentration [MIC], ≥1 μg/ml), with a higher prevalence of erm(B) (67.2%) than mef(A/E) (39.7%). erm(B) was associated with high-level EM resistance (MIC, ≥128 μg/ml) and distributed at high detection rates to major serotypes 23F (85.2%) and 6B (85.1%), as well as minor serotypes 3, 10A, 14, 15B, 15C, 19A, and 23A (>90%). While penicillin-resistant S. pneumoniae (PRSP) (penicillin G-MIC, 2-3 μg/ml) was detected in 7.8% of isolates from children, the most common PBP gene genotype was gPRSP (three altered genes pbp1a, 2x, and 2b; 38.3%), which was detected at higher rates (>60%) in the dominant serotypes 23F, 6B, and 19F, and minor serotypes 6D and 15A. Dominant serotypes in the S. pneumoniae isolates were generally similar to those reported for invasive strains, despite lower coverage rates by PCV7/13. The importance of further surveillance on incidence and drug resistance in the post-PCV7 period was suggested for non-PCV7/13 serotypes 6C, 6D, 10A, 15A, 15B, 15C, 23A, and 35B.

Exploitation of physiology and metabolomics to identify pneumococcal vaccine candidates

Streptococcus pneumoniae (the pneumococcus) is the etiologic agent of community-acquired pneumonia and invasive pneumococcal diseases such as septicemia and bacterial meningitis. The increasing antibiotic resistance and the suboptimal efficacy or limited serotype coverage of currently available vaccines urgently requires novel approaches in exploring new antimicrobials, therapeutic intervention strategies and vaccines. The current vaccine development strategies rely on the hypothesis that surface-exposed proteins, which are essential for pneumococcal virulence, are the most suitable candidates for future protein-based vaccines. Since virulence is closely linked with bacterial fitness, the potential of a pathogen to colonize and infect the host depends further on its physiology. This review summarizes the application of genome-wide techniques and their exploitation to decipher fundamental insights into bacterial factors associated with fitness, metabolism and virulence, leading to the discovery of vaccine candidates or antimicrobials.

Prediction and characterization of helper T-cell epitopes from pneumococcal surface adhesin A

Pneumococcal surface adhesin A (PsaA) is a multifunctional lipoprotein known to bind nasopharyngeal epithelial cells, and is significantly involved in bacterial adherence and virulence. Identification of PsaA peptides that optimally bind human leucocyte antigen (HLA) and elicit a potent immune response would be of great importance to vaccine development. However, this is hindered by the multitude of HLA polymorphisms in humans. To identify the conserved immunodominant epitopes, we used an experimental dataset of 28 PsaA synthetic peptides and in silico methods to predict specific peptide-binding to HLA and murine MHC class II molecules. We also characterized spleen and cervical lymph node (CLN) -derived T helper (Th) lymphocyte cytokine responses to these peptides after Streptococcus pneumoniae strain EF3030 challenge in mice. Individual, yet overlapping, peptides 15 amino acids in length revealed residues of PsaA that consistently caused the highest interferon-γ, interleukin-2 (IL-2), IL-5 and IL-17 responses and proliferation as well as moderate IL-10 and IL-4 responses by ex vivo re-stimulated splenic and CLN CD4⁺ T cells isolated from S. pneumoniae strain EF3030-challenged F1 (B6 × BALB/c) mice. In silico analysis revealed that peptides from PsaA may interact with a broad range of HLA-DP, -DQ and -DR alleles, due in part to regions lacking β-turns and asparagine endopeptidase sites. These data suggest that Th cell peptides (7, 19, 20, 22, 23 and 24) screened for secondary structures and MHC class II peptide-binding affinities can elicit T helper cytokine and proliferative responses to PsaA peptides.

Invasive pneumococci before the introduction of pneumococcal conjugate vaccine in Turkey: antimicrobial susceptibility, serotype distribution, and molecular identification of macrolide resistance

This study evaluates the antimicrobial susceptibilities and serotype distributions of invasive Streptococcus pneumoniae (SP) isolates identified in a Turkish hospital before the introduction of the 7-valent pneumococcal conjugate vaccine (PCV7). The susceptibilities of all isolates were determined by evaluating six antibiotics: penicillin (PEN), ceftriaxone (CRO), levofloxacin (LEV), erythromycin (ERY), clindamycin (CD), and vancomycin (VAN). Serotyping and amplification of macrolide resistance genes were performed. Sixteen (50%) and four (2%) isolates were resistant to PEN and LEV, respectively. No isolates demonstrated VAN resistance. Intermediate resistance to CRO was found in 4% of all invasive isolates. Twenty-three (12.6%) isolates were resistant to ERY. Four (2%) invasive SP isolates demonstrated multidrug resistance. Serogroups 3, 5, 6, 8, 9, and 23 were the most common in both age groups. The potential coverage rates of PCV7 and PCV13 were 44.1 and 66.1% in children and 39.8 and 71.5% in adults, respectively. Continuous surveillance of antimicrobial resistance is required.

Carriage rate and serotypes of Streptococcus pneumoniae amongst children in Thika Hospital, Kenya

Streptococcus pneumoniae is a major cause of morbidity and mortality worldwide. Rates of carriage are highest in infants and the elderly. The objectives of this study were to determine the rate of nasopharyngeal colonization by S. pneumoniae, and to describe the antibiotic resistant patterns and the serotypes of the carried isolates. A cross-sectional study design was used. Nasopharyngeal swabs were collected from 315 children in the months of October and November 2010 and processed to isolate S. pneumoniae. The isolates were serotyped by the Quellung reaction and their antibiotic susceptibilities assessed by the disc diffusion method. The overall nasopharyngeal carriage rate for S. pneumoniae was 17%. Seventeen serotypes were detected amongst 55 strains analysed: 6A, 23F, 19F, 13, 6B, 14A, 20, 7C, 1, 15B, 35B, 19A, 11A, 34, 5, 3 and 23A. Susceptibility testing revealed that nearly all (98%) were resistant to cotrimoxazole, 9% were resistant to penicillin and 7% to cefotaxime. Resistance to chloramphenicol and erythromycin was 2% and 4%, respectively. All isolates were fully sensitive to tetracycline.

High levels of cotrimoxazole resistance and some resistance to other antimicrobial agents commonly used in Thika District Hospital shows that there is need to revise antimicrobial policy in this region in the treatment of invasive pneumococcal infections. The frequent serotypes found in this study have previously been associated with pneumococcal infections in children. Several of these serotypes are included in the ten-valent vaccine and therefore use of this vaccine will help reduce pneumococcal infections in Thika.

A retrospective epidemiological study of invasive pneumococcal infections in children aged 0-5 years in Bahrain from 1 January 1999 to 31 December 2003

Pneumococcal diseases caused by the bacterium Streptococcus pneumoniae are a worldwide public health problem. The objective of this study was to determine the incidence of pneumococcal diseases in children aged <5 years in Bahrain. A total of 371 cases of pneumococcal infections in children aged <5 years, recorded in 5 hospitals in Bahrain from 1 January 1999 to 31 December 2003, were retrospectively reviewed. Case definition required microbiological confirmation (i.e., isolation of S. pneumoniae from blood, cerebrospinal fluid, or any other normally sterile biological fluid) or clinical diagnosis if microbiology test results were inconclusive. During the study period, the average annual incidence of invasive pneumococcal disease (IPD) in children aged <5 years was 115 per 100,000, ranging from 42 per 100,000 in 1999 to 208 per 100,000 in 2003. The annual incidence of IPD in children aged <1 year was 471 cases per 100,000. The reported annual incidence of microbiologically confirmed IPD (meningitis, septicemia, and bacteremia) increased from 3.91 per 100,000 in 1999 to 109.77 per 100,000 in 2003. The greatest disease burden was in children <2 years old: this age group included 75% of meningitis cases, 89.2% of septicemia/bacteremia cases and 81.5% of pneumococcal pneumonia cases. In conclusion, the estimated annual incidence of IPD in children aged <5 years in Bahrain was unusually high. Factors responsible may include the wide and uncontrolled use of antibiotics, the mobility of a large proportion of the population, and possible susceptibility to risk factors such as sickle cell anemia and respiratory illnesses.

Screening of solanum surrattense for antibacterial, antifungal, phytotoxic and haemagglutination

OBJECTIVE

Plants produce a variety of useful bioactive materials that have been used to cure different ailments of human beings. With the same idea in mind, the crude methanolic extract and various fractions of Solanum surrattense were screened for antibacterial, antifungal, phytotoxic and heamagglutination activities.

METHODS

Standardized assays were followed for the determination of antibacterial, antifungal phytotoxic and heamagglutination activity.

RESULTS

The results of the antibacterial showed that crude methanolic extract was significantly active against Staphylococcus aureus (86%) The n-hexane fraction showed good activity against Pseudomonas aerogenosa (66.6%) and Bacillus subtilus (66.6%). The crude methanolic extract and various fractions were inactive against all test fungi. The crude methanolic extract, n-hexane, CHCl3 and aqueous fractions showed moderate phytotoxic activities of 46.67%, 40.00%, 33.34% and 33.34% respectively at 1000 microg/mL. The crude methanolic extract and various fractions S. surrattense were unable to agglutinate RBCs of the human blood indicating that this species lack phytolectins.

CONCLUSION

The test sample showed significant antibacterial activity, no antifungal and heamagglutination activity while moderate phytotoxic was observed against Lemna minor L.

PspA family distribution, antimicrobial resistance and serotype of Streptococcus pneumoniae isolated from upper respiratory tract infections in Japan

Background

The protection against pneumococcal infections provided by currently available pneumococcal polysaccharide conjugate vaccines are restricted to the limited number of the serotypes included in the vaccine. In the present study, we evaluated the distribution of the pneumococcal capsular type and surface protein A (PspA) family of pneumococcal isolates from upper respiratory tract infections in Japan.

Methods

A total of 251 S. pneumoniae isolates from patients seeking treatment for upper respiratory tract infections were characterized for PspA family, antibiotic resistance and capsular type.

Results

Among the 251 pneumococci studied, the majority (49.4%) was identified as belonging to PspA family 2, while most of the remaining isolates (44.6%) belonged to family 1. There were no significant differences between the distributions of PspA1 versus PspA2 isolates based on the age or gender of the patient, source of the isolates or the isolates’ susceptibilities to penicillin G. In contrast, the frequency of the mefA gene presence and of serotypes 15B and 19F were statistically more common among PspA2 strains.

Conclusion

The vast majority of pneumococci isolated from the middle ear fluids, nasal discharges/sinus aspirates or pharyngeal secretions represented PspA families 1 and 2. Capsular serotypes were generally not exclusively associated with certain PspA families, although some capsular types showed a much higher proportion of either PspA1 or PspA2. A PspA-containing vaccine would potentially provide high coverage against pneumococcal infectious diseases because it would be cross-protective versus invasive disease with the majority of pneumococci infecting children and adults.

The use of macrolides in respiratory tract infections

Macrolides have enjoyed continued use for over 40 years, being increasingly usedfor the treatment of respiratory tract infections. Newer macrolides have been introduced that show improved absorption after oral administration, better gastrointestinal tolerance, and delivery of increased amounts of drug to the infection site. Macrolides are commonly used in community-acquired pneumonia, as well as in atypical pneumonia and legionellosis. The newer macrolides, in comparative studies, have been shown to be as effective as the conventional therapies for treating acute otitis media, acute sinusitis and acute pharyngitis, with a low incidence of side-effects. However, dosing can be simplified because of their unique pharmacokinetic properties. Limitations in the use of macrolides for respiratory infections include rather marginal activity in the most severe cases of Haemophilus influenzae infections, lack of activity against Klebsiella and other coliforms, which precludes their use as single agents in the therapy of pneumonia in patients with significant underlying disease or in the elderly, and development of resistance in streptococci and staphylococci.

Risk factors for multidrug-resistant invasive pneumococcal disease in South Africa, a setting with high HIV prevalence, in the prevaccine era from 2003 to 2008

The emergence of multidrug-resistant (MDR) Streptococcus pneumoniae complicates disease management. We aimed to determine risk factors associated with MDR invasive pneumococcal disease (IPD) in South Africa and evaluate the potential for vaccination to reduce disease burden. IPD data collected by laboratory-based surveillance from 2003 through 2008 were analyzed. Multidrug resistance was defined as nonsusceptibility to any three or more different antibiotic classes. Risk factors for multidrug resistance were evaluated using multivariable logistic regression. Of 20,100 cases of IPD identified, 3,708 (18%) had MDR isolates, with the proportion increasing from 16% (461/2,891) to 20% (648/3,326) (P < 0.001) over the study period. Serotypes included in the 13-valent pneumococcal conjugate vaccine (PCV13) accounted for 94% of MDR strains. Significant risk factors for MDR IPD included PCV13 (1,486/6,407; odds ratio [OR] of 6.3; 95% confidence interval [CI] of 5.0 to 7.9) and pediatric (3,382/9,980; OR of 12.8; 95% CI of 10.6 to 15.4) serotypes, age of <5 (802/3,110; OR of 2.0; 95% CI of 1.8 to 2.3) or ≥65 (39/239; OR of 1.5; 95% CI of 1.0 to 2.2) years versus age of 15 to 64 years, HIV infection (975/4,636; OR of 1.5; 95% CI of 1.2 to 1.8), previous antibiotic use (242/803; OR of 1.7; 95% CI of 1.4 to 2.1), previous hospital admissions (579/2,450; OR of 1.2; 95% CI of 1.03 to 1.4), urban location (883/4,375; OR of 2.0; 95% CI of 1.1 to 3.5), and tuberculosis treatment (246/1,021; OR of 1.2; 95% CI of 1.03 to 1.5). MDR IPD prevalence increased over the study period. The effect of many of the MDR risk factors could be reduced by more judicious use of antibiotics. Because PCV13 serotypes account for most MDR infections, pneumococcal vaccination may reduce the prevalence of multidrug resistance.

R-roscovitine reduces lung inflammation induced by lipoteichoic acid and Streptococcus pneumoniae

Bacterial pneumonia remains associated with high morbidity and mortality. The gram-positive pathogen Streptococcus pneumoniae is the most common cause of community-acquired pneumonia. Lipoteichoic acid (LTA) is an important proinflammatory component of the gram-positive bacterial cell wall. R-roscovitine, a purine analog, is a potent cyclin-dependent kinase (CDK)-1, -2, -5 and -7 inhibitor that has the ability to inhibit the cell cycle and to induce polymorphonuclear cell (PMN) apoptosis. We sought to investigate the effect of R-roscovitine on LTA-induced activation of cell lines with relevance for lung inflammation in vitro and on lung inflammation elicited by either LTA or viable S. pneumoniae in vivo. In vitro R-roscovitine enhanced apoptosis in PMNs and reduced tumor necrosis factor (TNF)-α and keratinocyte chemoattractant (KC) production in MH-S (alveolar macrophage) and MLE-12/MLE-15 (respiratory epithelial) cell lines. In vivo R-roscovitine treatment reduced PMN numbers in bronchoalveolar lavage fluid during LTA-induced lung inflammation; this effect was reversed by inhibiting apoptosis. Postponed treatment with R-roscovitine (24 and 72 h) diminished PMN numbers in lung tissue during gram-positive pneumonia; this step was associated with a transient increase in pulmonary bacterial loads. R-roscovitine inhibits proinflammatory responses induced by the gram-positive stimuli LTA and S. pneumoniae. R-roscovitine reduces PMN numbers in lungs upon LTA administration by enhancing apoptosis. The reduction in PMN numbers caused by R-roscovitine during S. pneumoniae pneumonia may hamper antibacterial defense.

Structural characterization of Zn(II)-, Co(II)-, and Mn(II)-loaded forms of the argE-encoded N-acetyl-L-ornithine deacetylase from Escherichia coli

The Zn, Co, and Mn K-edge extended X-ray absorption fine structure (EXAFS) spectra of the N-acetyl-l-ornithine deacetylase (ArgE) from Escherichia coli, loaded with one or two equivalents of divalent metal ions (i.e., [Zn(II)_(ArgE)], [Zn(II)Zn(II)(ArgE)], [Co(II)_(ArgE)], [Co(II)Co(II)(ArgE)], [Mn(II)_(ArgE)], and [Mn(II)Mn(II)(ArgE)]), were recorded. The Fourier transformed data (FT) for [Zn(II)_(ArgE)], [Zn(II)Zn(II)(ArgE)], [Co(II)_(ArgE)] and [Co(II)Co(II)(ArgE)] are dominated by a peak at 2.05Å, that can be fit assuming five or six light atom (N,O) scatterers. Inclusion of multiple-scattering contributions from the outer-shell atoms of a histidine-imidazole ring resulted in reasonable Debye-Waller factors for these contributions and a slight reduction in the goodness-of-fit value (f'). Furthermore, the data best fit a model that included a M-M vector at 3.3 and 3.4Å for Zn(II) and Co(II), respectively, suggesting the formation of a dinuclear site. Multiple scattering contributions from the outer-shell atoms of a histidine-imidazole rings are observed at ~3 and 4Å for Zn(II)- and Co(II)-loaded ArgE suggesting at least one histidine ligand at each metal binding site. Likewise, EXAFS data for Mn(II)-loaded ArgE are dominated by a peak at 2.19Å that was best fit assuming six light atom (N,O) scatterers. Due to poor signal to noise ratios for the Mn EXAFS spectra, no Mn-Mn vector could be modeled. Peak intensities for [M(II)_(ArgE)] vs. [M(II)M(II)(ArgE)] suggest the Zn(II), Co(II), and Mn(II) bind to ArgE in a cooperative manner. Since no structural data has been reported for any ArgE enzyme, the EXAFS data reported herein represent the first structural glimpse for ArgE enzymes. These data also provide a structural foundation for the future design of small molecules that function as inhibitors of ArgE and may potentially function as a new class of antibiotics.

Evaluation of Iranian pediatric specialists' attitude and knowledge regarding approach to patients with acute otitis media

BACKGROUND

The ministry of health and medical education of Iran and many other countries advice physicians to use this guideline for diagnosis and treatment of acute otitis media (AOM), but there is not any evaluation of effectiveness and obedience of this guideline, so the aim of this study was to evaluate the attitude of pediatricians, the most important group that interfere with these patients in treatment of acute otitis media.

METHODS

A total of 120 anonymous surveys were mailed to 120 pediatrician in Tehran (Iran) to evaluate pattern of diagnosis and treatment of AOM in these physicians. Age, gender, place of work, attitude of diagnosis and treatment were asked by anonymous survey.

RESULTS

Sixty-two completed surveys were received, for a response rate of 51%. There was no significant difference between responders in these survey and scenarios, according to sex, age, practice setting, graduation year or the number of AOM patients visiting each month.

CONCLUSION

Our study seems to add new insights to the previous literature on management of AOM according to guideline. We can assess the impact of guidelines on the usual practice of practitioners in evidenced-based management of AOM.