Distribution of capsular types and drug resistance patterns of invasive pediatric Streptococcus pneumoniae isolates in Teheran, Iran

Serotype distribution of invasive pneumococcal disease from countries of the WHO Africa, Americas, Eastern Mediterranean, South-East Asia, and Western Pacific regions: a systematic literature review from 2010 to 2021

Background

Most publications on invasive pneumococcal disease (IPD) serotype distribution are from about 20 countries (Australia, Canada, China, European Union members, Japan, New Zealand, South Korea, and USA). Here, we reviewed the literature among underrepresented countries in the Americas (AMRO), Africa (AFRO), Eastern Mediterranean (EMRO), South-East Asia (SEARO), and Western Pacific (WPRO) WHO regions.

Methods

We performed a systematic review of the most recent IPD serotype surveillance publications (from 01/01/2010 to 31/12/2021, Medline/Embase) in those WHO regions. Selection criteria were delineated by contemporality, within-country geographical scope, and number of samples. Reported serotype distributions for each country were stratified by age group, pneumococcal conjugate vaccine (PCV) serotype category (considering undifferentiated serotypes), and PCV program period (pre-PCV, intermediate, or PCVhv [higher valency PCV formulation]). Pre-PCV period pooled data estimated PCV serotype category distribution by age group across WHO regions, while for the PCVhv period, country-level dataset tables were prepared.

Results

Of 2,793 publications screened, 107 were included (58 pediatric, 11 adult, 37 all ages, and one comprising every age group). One-third of eligible countries (51/135) published serotype distribution, ranging from 30 to 43% by WHO region. Considering number of samples per WHO region, a few countries prevailed: AMRO (Brazil), AFRO (South Africa, Malawi, and Burkina Faso), and WPRO (Taiwan). In the pre-PCV period, PCV13 formulation serotypes predominated: ranging from 74 to 85% in children and 58-86% in adults in the different WHO regions. The PCVhv period represented half of the most recent IPD surveillance by countries (26/51). Undifferentiated serotypes represented >20% of IPD from most countries (34/51).

Conclusion

Ubiquity of undifferentiated serotypes among the publications could constrain estimates of PCV program impact and of serotype coverage for newer PCVhv formulations; consequently, we recommend that countries favor techniques that identify serotypes specifically and, rather than reporting PCV formulation serotype distributions, provide serotype results individually.

Systematic review registration

The protocol has been prospectively registered at PROSPERO, identifier: CRD42021278501. https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=278501.

Assessing bacterial prevalence and resistance in paediatric meningitis: safeguarding the central nervous system

Introduction

Paediatric bacterial meningitis (PBM) represents a major contributor to childhood morbidity and mortality globally, with heightened susceptibility in low- and middle-income nations where antimicrobial resistance (AMR) is highly prevalent. Pakistan exemplifies this setting, with widespread antibiotic overuse driving AMR expansion. Thus, expediting PBM diagnosis and targeted antibiotic therapy is imperative yet challenged by the dynamic local epidemiology. This study aimed to delineate the recent bacterial etiologies and AMR profiles of PBM from a major Pakistani diagnostics laboratory to inform empirical treatment.

Materials and methods

This prospective observational investigation evaluated PBM epidemiology in patients under 18 years old admitted to the study hospital. Standard cerebrospinal fluid analysis identified bacterial pathogens and antibiotic susceptibility patterns.

Results

Among 171 PBM cases, 152 (88.9%) had bacterial isolates confirmed via culture. The cohort was 42.7% male with a mean age of 3 months. The most prevalent pathogens among infants younger than 3 months were Escherichia coli, Enterococcus faecium, and Staphylococcus epidermidis, contrasting with S. epidermidis, Streptococcus pneumoniae, and Staphylococcus hominis predominating in older children. Staphylococcal isolates exhibited considerable penicillin and erythromycin resistance but maintained vancomycin and linezolid susceptibility. Other resistance patterns varied.

Conclusion

These findings highlight the pressing threat of paediatric AMR in Pakistan, underscoring the need for vigilant AMR surveillance and judicious antimicrobial use. This study provides a reference to current PBM epidemiology to guide context-specific empirical therapy.

Monitoring Over a Decade in the Serotype Prevalence of Streptococcus pneumoniae in Iran: A Systematic Review and Meta-analysis

BACKGROUND

There is no comprehensive information about the circulating serotypes of Streptococcus pneumoniae in Iran in recent years. This study aimed to summarize information about the changes over a decade in the serotype prevalence of S. pneumoniae in Iran.

METHODS

We performed a comprehensive search in PubMed/Medline, Web of Science, Science Direct, and the Iranian Database, such as Magiran and SID, from January 2011 to February 2023. The systematic process, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), was carried out by two researchers who were both independent and calibrated. Statistical analyses were carried out using Comprehensive Meta-Analysis software. Identifying and measuring heterogeneity were done using I2 and the chi-square test. Finally, Begg's rank correlation test was used in combination with a funnel plot to evaluate any possible publication bias.

RESULTS

The search returned 16 relevant results, with a total of 1575 isolates. Of those studies, eight studies reported the distribution of S. pneumoniae serotypes among patients, three studies among healthy individuals, and five studies among both groups. As the meta-analysis revealed, the most common serotypes were 23F (n = 299, 14.1% [95% CI: 9.7-19.9]; I2 = 84.3%; P<0.001 for heterogeneity), 19F (n = 221, 13.4% [95% CI: 9.9-17.9; I2 = 76.7%; P<0.001 for heterogeneity]), and 19A (n = 102, 8.7% [95% CI: 6.5-11.7; I2 = 54.3%; P<0.001 for heterogeneity]). Moreover, Begg's test (P = 0.160, 0.173, and 0.176 for 23F, 19F, and 19A, respectively) showed no evidence of publication bias.

CONCLUSION

Based on our pooled results, the majority of the serotypes of pneumococci in the Iranian population were 23F, 19F, and 19A, respectively, over the last decade. The findings can be valuable in selecting effective pneumococcal vaccine candidates and targeted antibiotics in Iranian patients.

Emerging pneumococcal serotypes in Iraq: scope for improved vaccine development

Pneumococcal disease is a global public health concern as it affects the young, aged and the immunocompromised. The development of pneumococcal vaccines and their incorporation in the immunization programs has helped to reduce the global burden of disease. However, serotype replacement and the emergence of non-vaccine serotypes as well as the persistence of a few vaccine serotypes underscores the need for development of new and effective vaccines against such pneumococcal serotypes. In the Middle East, places of religious mass gatherings are a hotspot for disease transmission in addition to the global risk factors. Therefore, the periodic surveillance of pneumococcal serotypes circulating in the region to determine the effectiveness of existing prevention strategies and develop improved vaccines is warranted. Currently, there is a lack of serotype prevalence data for Iraq due to inadequate surveillance in the region. Thus, this review aims to determine the pneumococcal serotypes circulating in Iraq which may help in the development and introduction of improved pneumococcal vaccines in the country.

Serotype Distribution and Multi Locus Sequence Type (MLST) of Erythromycin-Resistant Streptococcus Pneumoniae Isolates in Tehran, Iran

Background

The number of erythromycin-resistant Streptococcus pneumoniae has significantly increased around the world. The present study aimed to determine the serotype distribution and molecular epidemiology of the erythromycin-resistant Streptococcus pneumoniae (ERSP) isolated from patients with invasive disease.

Methods

A total of 44 Streptococcus pneumoniae isolates were tested for susceptibility to several antimicrobial agents. Additionally, the polymerase chain reaction (PCR) was applied to evaluate ERSP isolates in terms of the presence of erythromycin resistance genes (e.g., ermB and mefA). The isolates were serotyped using the sequential multiplex-PCR method, and molecular epidemiology was assessed through the multilocus sequence typing (MLST) analysis.

Results

The results represented multidrug resistance (MDR) in approximately half of the pneumococcal isolates. Among 22 ERSP isolates, 20 (90.9%) and 12 (56%) ones contained ermB and mefA, respectively. Further, 14 (31.8%), 3 (22.7%), and 19A (18.1%) were the common serotypes among the isolates. No significant correlation was observed between serotypes and erythromycin resistance genes. Furthermore, the MLST results revealed 18 different sequence types (STs), the top ones of which were ST3130 (3 isolates) and ST166 (3 isolates). Population genetic analysis disclosed that CC63 (32%), CC156 (18%), and CC320 (18%) were identified as the predominant clonal complexes.

Conclusions

The ERSP isolates exhibited high genetic diversity. The large frequency of MDR isolates suggests the emergence of high resistant strains, as well as the need to implement vaccination in the immunization schedule of Iran. These accumulating evidences indicate that 13-valent pneumococcal conjugate vaccines provided higher serotype coverage in the ERSP isolates.

Nasopharyngeal Carriage of Streptococcus pneumoniae Serotypes Among Healthy Children in Northern India

Streptococcus pneumoniae (SP) infections cause morbidity and mortality among children worldwide. Hence India introduced 13-valent pneumococcal conjugate vaccine (PCV-13) in 2017 in a phased manner. The primary objective of this study was to assess the proportion of healthy children having nasopharyngeal colonization (NP) with SP. Secondary objective was to determine prevalent serotype of SP among the PCV13 vaccinated and non-vaccinated children. This cross-sectional study was conducted in 4 hospitals of Lucknow District, Northern India. Three hundred healthy children (2-59 months) were recruited between July and August 2019 from vaccination-clinics of hospitals. NP specimen was cultured using 5% sheep blood agar plate containing gentamicin. Pneumococcal isolates were identified by optochin sensitivity and bile-solubility tests. Serotyping was done using Quellung Method. Of the 300 healthy children, 56.7% (170/300) were males and 59.3% (181/300) had received at least one dose of PCV13 vaccine. The NP carriage rate of SP among healthy children was 37.7% (113/300). Vaccine serotypes were found in 33.3% (22/66) in PCV vaccinated children and 48.9% (23/47) in non-vaccinated children (p 0.09). Common vaccine serotypes that isolated were: 18C, 19A, 19F, 23F, 3, 4, 6A, 6B, 9 V. Thus more than one-third of healthy children had NP colonization with SP. Adjusting for age, there was a trend for significant reduction in vaccine serotypes in the NP with one doses versus two or more doses (ptrend = 0.04).

Co-infection with dual Streptococcus pneumoniae serotypes as a cause of pediatric bacterial meningitis in Iran: a multi-center cross-sectional study

Background

Meningitis is considered a life-threatening infection with high mortality all over the world. Hemophilus influenzae (H. influenzae) and Streptococcus pneumoniae (S. pneumoniae) are regarded as the two most common infectious agents causing bacterial meningitis. This study aimed to identify H. influenzae and S. pneumoniae serotypes in blood and cerebrospinal fluid (CSF) of pediatric patients with meningitis, using polymerase chain reaction (PCR).

Methods

This multi-center cross-sectional study included 284 children with suspected meningitis referred to 4 target hospitals. Overall, 412 samples (128 blood and 284 CSF samples) were obtained from the patients from November 14, 2016 to November 15, 2017. The extracted DNA was examined using multiplex real time PCR to screen for S. pneumoniae and H. influenzae. S. pneumoniae serotyping was also done by multiplex PCR.

Results

Out of 284 CSF specimens, 22 were positive for ply S. pneumoniae. Of 20 DNA samples meeting the Quality Control (QC) standards for serotyping, 7 (35%), 6 (30%), 2 (10%), 2 (10%), 2 (10%), 1 (5%), 1 (5%), 1 (5%), 1 (5%) and 1 (5%) were positive for serotypes 3, 11A, 6A, 14, 7C, 23F, 23B, 19A, and 19F and 5, respectively. Overall, nine samples were positive for two serotypes, of whom 3 and 11A were the most common from Tehran province. Of note, one of these CSF samples showed a new co-infection with serotypes 7C and 14. Also, 6 samples (30%) were positive for H. influenzae detected by bexA primer. None of the blood samples were positive for S. pneumoniae or H. influenzae.

Conclusion

Co-infection with S. pneumoniae serotypes can occur in bacterial meningitis and it might be missed if all serotypes are not evaluated in CSF specimens.

Determination of Streptococcus pneumonia Serotypes Isolated from Clinical Specimens: A Step Toward the Production of a Native Vaccine in Iran

Background: Streptococcus pneumoniae remains a major cause of invasive streptococcal diseases among all age groups, particularly infants and the elderly. Objectives: This study aimed to recognize and determine S. pneumoniae serotypes isolated from clinical specimens by multiplex polymerase chain reaction (PCR). Methods: A total of 105 pneumococcal strains were collected from nonvaccinated cases within the age range of 10 days to 92 years from five provinces of Iran within June 2017 to August 2019. The strains were cultured on blood agar. Biochemical analyses and molecular tests were performed for the primary identification of bacterial isolates. Capsular typing was carried out by multiplex PCR assay. Primers that target the capsular polysaccharide site were used in this study. Results: Out of 130 studied clinical specimens, 105 isolates of S. pneumoniae were detected and identified. The most frequently isolated capsular types were 6B, 14, 19A, and 1. Serotype distribution consisted of 83.5% of vaccine serotype and 16.5% of nonvaccine serotype. The serotype 6B was significantly more frequent (P < 0.05) among the invasive clinical isolates (75%) compared to that among their noninvasive counterparts (25%). The distribution of 13-valent pneumococcal conjugate vaccine (PCV-13) serotypes in invasive pneumococcal disease (IPD) and non-IPD revealed 83% and 84% of the isolated serotypes, respectively. Moreover, 83.5% of all the serotypes identified in the study were covered by PCV-13 serotypes. Conclusions: The common serotypes of invasive and noninvasive groups in Iran are covered by PCV-13.

Epidemiology and Drug Resistance of Pathogens Isolated from Cerebrospinal Fluids at a Children's Medical Center in Eastern China During 2006-2020

Objective

To investigate the epidemiology and drug resistance of pathogens isolated from cerebrospinal fluid samples at a children's medical center in eastern China and provide the basis for anti-infection treatments.

Methods

In all, 307 non-duplicated strains of pathogens were isolated from cerebrospinal fluid samples in the Children's Hospital of Soochow University from January 2006 to December 2020. Mass spectrometry was used for pathogen identification. The VITEK 2 Compact system and Kirby-Bauer method were applied to determine antimicrobial susceptibility.

Results

Among the 307 isolates, gram-positive bacteria, gram-negative bacteria and fungi accounted for 60.26%, 34.53%, and 5.21%, respectively. The most prevalent pathogens were Streptococcus pneumoniae (26.06%), Escherichia coli (20.20%) and Streptococcus agalactiae (17.26%). The number of isolates was highest in winter. The most prevalent gram-positive bacterium in children <6 months old was Streptococcus agalactiae, while Streptococcus pneumoniae was the most in children were >6 months old. The drug resistance of gram-positive bacteria, fungi and Haemophilus influenza were not high. In addition, 35 strains of gram-negative bacteria produced extended-spectrum β-lactamases (ESBLs) and 6 strains were identified as multidrug-resistant (MDR) bacteria. These strains showed much higher resistance to the antibiotics than other strains.

Conclusion

Cases of meningitis among children have increased in the past 15 years and MDR bacteria were also identified. The emergence of MDR bacteria is a cause for great concern and requires further investigation.

Multiplex polymerase chain reaction detection of Streptococcus pneumoniae and Haemophilus influenzae and their antibiotic resistance in patients with community-acquired pneumonia from southwest Iran

BACKGROUND

This study aimed to evaluate the occurrence of Streptococcus pneumoniae and Haemophilus influenzae in sputum of patients with community-acquired pneumonia (CAP) using culture and multiplex polymerase chain reaction (M-PCR) methods and to survey the antibiotic resistance patterns of aforesaid isolates.

RESULT

In total, 23.9 % (n = 22/92) of sputum samples showed positive results in the culture method. S. pneumoniae and H. influenzae were isolated from 15 (16.3 %) and 7 (7.6%) samples, respectively. Using M-PCR, 44 (47.8 %) samples were positive for S. pneumoniae and H. influenzae. Of these, S. pneumoniae and H. influenzae were detected in 33 (35.8%) and 11 (11.9%) of the sputum samples, respectively. The sensitivity, specificity, and accuracy rates of PCR in detection of S. pneumoniae in comparison with culture method were 100, 76.6, and 83.6%, respectively. While, the sensitivity, specificity, and accuracy rates of PCR in detection of H. influenzae in comparison with culture method were 100, 95.3, and 95.8%, respectively. Out of 11 isolates of H. influenzae, two strains confirmed as H. influenzae type b (Hib) and 3 isolates were type f. However, 6 isolates were non-typable. The co-trimoxazole and amoxicillin/clavulanate were the less effective antibiotics against S. pneumonia and H. influenzae, respectively. Ceftriaxone with 13.3% resistance rates was the most effective antibiotic against S. pneumoniae, while, clarithromycin, ceftriaxone, and gentamicin with resistance rates of 28.6% for each one were the most effective chemicals against H. influenzae isolates.

CONCLUSION

In this study, the prevalence of S. pneumoniae was more than H. influenzae using culture and M-PCR methods. The M-PCR provided better efficiency in detecting the bacterial agents in CAP patients compared to culture method. This method can improve the early detection of pathogens contributed to CAP. The drug resistant S. pneumoniae and H. influenzae indicated the need to develop a codified monitoring program to prevent further spread of these strains.

Prevalence of Invasive Streptococcus pneumoniae Infections among Iranian Children: A Systematic Review and Meta-Analysis

Background:

Streptococcus pneumoniae is an important pathogen of children, mostly in developing countries. We aimed to investigate the prevalence of invasive S. pneumoniae among Iranian children using a systematic review and meta-analysis.

Methods:

A systematic search was carried out to identify papers published by Iranian authors in the Web of Science, PubMed, Scopus, and Google Scholar electronic databases from January of 2010 to December of 2017. Then, seven publications that met our inclusion criteria were selected for data extraction and analysis.

Results:

Totally, one study was multicenter, and six were single-center based studies. Meanwhile, all of the included studied performed among hospitalized patients. Seven studies reported the prevalence of invasive S. pneumoniae isolated from children, of these the pooled prevalence of S. pneumoniae was 2.5% (95% CI: 0.7%–9.1%).

Conclusion:

The overall prevalence of invasive S. pneumoniae infections among Iranian children is low (2.5%). However, further clinical studies are required to elucidate the burden of infections among Iranian children, especially in eastern regions.

Is Penicillin-Nonsusceptible Streptococcus pneumoniae a Significant Challenge to Healthcare System? A Systematic Review and Meta-Analysis

BACKGROUND

In recent years, antibiotic-resistant pathogens including penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) have posed serious threats against human health. The aim of this meta-analysis was to investigate the prevalence of Streptococcus pneumoniae drug resistance particularly the incidence of PNSP strains in Iran.

METHODS

A systematic search was done in national and international electronic databases using Persian and English keywords. Up until May 20, 2020, a total of 58 publications were detected as eligible articles based on the inclusion and exclusion criteria, and then the selected studies were enrolled for data extraction and meta-analysis according to the PRISMA guidelines.

RESULTS

A high rate of PNSP (46.9%) and multidrug-resistant (MDR) S. pneumoniae (45.3%) in our isolates were evident. Furthermore, total frequency resistance to other drugs in S. pneumoniae was as follows: erythromycin 41.1%, azithromycin 53.2%, tetracycline 39.9%, levofloxacin 1.7%, rifampin 1.2%, clindamycin 31.7%, vancomycin 1.7%, trimethoprim/sulfamethoxazole 63.9%, chloramphenicol 20%, ceftriaxone 10.9%, amoxicillin 30.5%, ciprofloxacin 8.3%, imipenem 6.1%, linezolid 0%, and cefotaxime 8.3%.

CONCLUSION

Although the overall prevalence of cephalosporin- and carbapenem-resistant Streptococcus pneumoniae was low, penicillin-resistant strains, especially PNSP, could become a significant challenge to the healthcare system in Iran. Hence, the prescription of penicillin as the first-choice antibiotic in the treatment of S. pneumoniae infections should be avoided.

A Systematic Review and Meta-Analysis of Serotype Distribution of Streptococcus Pneumoniae in Iran: Practical Evidence to Optimizing Local Vaccination Protocols

BACKGROUND

Little is known regarding the burden of predominant circulating serotypes of Streptococcus pneumoniae in Iran. Therefore, this study aimed to investigate the serotype distribution of pneumococcal diseases in Iran by using a comprehensive systematic review of available articles. ; Methods: A systematic literature search was carried out to identify papers published by Iranian authors in the Web of Science, PubMed, Scopus, Embase and Google Scholar electronic databases from January 2000 to December 2018. Then, eight publications that met our inclusion criteria were selected for data extraction and analysis by Comprehensive Meta-Analysis software. ; Results: In total, three studies reported the distribution of S. pneumoniae serotypes among patients, two studies among healthy individuals, and three studies among both groups. Of those studies, serotype 19A/F (17.9%; 95% CI: 13.6-23.0) was the most circulating serotype followed by 23A/F (12.3%; 95% CI: 7.7-19.2), 6A/B (11.0%; 95% CI: 8.0-14.9), and 14 (8.8%; 95% CI: 5.8-13.2). In contrast, the lowest circulating serotype was 60 (0.02%; 95% CI: 0.0-1.2), 29 (0.07%; 95% CI: 0.01-5.0), and 36 (0.09%; 95% CI: 0.04-2.1). Meta-regression results showed that prevalence of serotype 23A/F significantly increased each year about 0.2% (95% CI: 0.1-0.3, P <0.001, tau2 <0.001). ; Conclusion: In the present study, it was found that over the last decade, the most prevalent serotypes in Iran were 19, 23, 6, and 14, respectively. These findings provide practical evidence to select effective pneumococcal vaccine candidates for the prevention of invasive diseases in Iranian patients and also to compare our situation with others.

Characterization of Blood-isolated, Penicillin-Nonsusceptible Streptococcus pneumoniae From Children Between 2014 and 2018 in Bojnurd, Iran

Background: Streptococcus pneumoniae is one of the common bacterial pathogens in pediatrics. In this study, we performed antimicrobial susceptibility testing, serotyping, and molecular typing of blood-isolated strains of pneumococci in Bojnurd. Objectives: In the current study, blood-isolated, penicillin-nonsusceptible S. pneumoniae strains were subjected to antimicrobial susceptibility testing and typing of capsular polysaccharides using the quelling reaction and PCR method, as well as genotyping using the Multi Locus Sequence Typing (MLST) method. Methods: In this study, 51 S. pneumoniae strains were isolated from blood samples of children less than five-years-old in 2014 - 2018. Antibiogram was performed using the Kirby-Bauer method. All of the isolates were serotyped by the Quelling reaction and PCR. The MLST method was applied to determine the molecular types. Results: Our study revealed that the most common serotypes of blood-isolated pneumococci were 19A, 6A/B, 1, 23F, 19F, 14, 15B/C, and 15A, and the common serotypes in Penicillin-nonsusceptible pneumococci (PNSP) isolates were 19F, 19A, 23F, 14, and finally 15A, 6A/B, 1, and 15B/C. The MLST analysis of PNSP isolates revealed that three highly resistant isolates with MIC ≥ 16 belonged to Sweden15A-25-19A (ST63), Taiwan19F-14-1 (ST236), and Taiwan19F-14 (ST236) clones. Conclusions: Regarding the common serotypes in this study, it seems that PCV-13 is a suitable choice for vaccination in this area. We also observed a high prevalence of PNSP and multi-drug resistant (MDR) strains between 2014 and 2018. It seems that the Taiwan19F-14 clone and its related STs played an essential role in the diffusion of antibiotic-resistant S. pneumoniae isolates in Bojnurd.

Prevalence and antimicrobial resistance patterns of bacteria isolated from cerebrospinal fluid among children with bacterial meningitis in China from 2016 to 2018: a multicenter retrospective study

Background

Pediatric bacterial meningitis (PBM) remains a devastating disease that causes substantial neurological morbidity and mortality worldwide. However, there are few large-scale studies on the pathogens causing PBM and their antimicrobial resistance (AMR) patterns in China. The present multicenter survey summarized the features of the etiological agents of PBM and characterized their AMR patterns.

Methods

Patients diagnosed with PBM were enrolled retrospectively at 13 children’s hospitals in China from 2016 to 2018 and were screened based on a review of cerebrospinal fluid (CSF) microbiology results. Demographic characteristics, the causative organisms and their AMR patterns were systematically analyzed.

Results

Overall, 1193 CSF bacterial isolates from 1142 patients with PBM were obtained. The three leading pathogens causing PBM were Staphylococcus epidermidis (16.5%), Escherichia coli (12.4%) and Streptococcus pneumoniae (10.6%). In infants under 3 months of age, the top 3 pathogens were E. coli (116/523; 22.2%), Enterococcus faecium (75/523; 14.3%), and S. epidermidis (57/523; 10.9%). However, in children more than 3 months of age, the top 3 pathogens were S. epidermidis (140/670; 20.9%), S. pneumoniae (117/670; 17.5%), and Staphylococcus hominis (57/670; 8.5%). More than 93.0% of E. coli isolates were sensitive to cefoxitin, piperacillin/tazobactam, cefoperazone/sulbactam, amikacin and carbapenems, and the resistance rates to ceftriaxone, cefotaxime and ceftazidime were 49.4%, 49.2% and 26.4%, respectively. From 2016 to 2018, the proportion of methicillin-resistant coagulase-negative Staphylococcus isolates (MRCoNS) declined from 80.5 to 72.3%, and the frequency of penicillin-resistant S. pneumoniae isolates increased from 75.0 to 87.5%. The proportion of extended-spectrum β-lactamase (ESBL)-producing E. coli fluctuated between 44.4 and 49.2%, and the detection rate of ESBL production in Klebsiella pneumoniae ranged from 55.6 to 88.9%. The resistance of E. coli strains to carbapenems was 5.0%, but the overall prevalence of carbapenem-resistant K. pneumoniae (CRKP) was high (54.5%).

Conclusions

S. epidermidis, E. coli and S. pneumoniae were the predominant pathogens causing PBM in Chinese patients. The distribution of PBM causative organisms varied by age. The resistance of CoNS to methicillin and the high incidence of ESBL production among E. coli and K. pneumoniae isolates were concerning. CRKP poses a critical challenge for the treatment of PBM.

Serotype distribution of Streptococcus pneumoniae among healthy carriers and clinical patients: a systematic review from Iran

Streptococcus pneumoniae is associated with high morbidity and mortality in the world. Commercially licensed and available pneumococcal conjugate vaccines (PCVs) contain 10 (PCV10) and 13 (PCV13) pneumococcal serotypes. The most common serotypes of S. pneumoniae causing clinical diseases and carriers of S. pneumoniae in Iran are not yet known. Reviewing and reporting trends in the distribution of pneumococcal serotypes in Iran will be useful for policy-making as PCV is being introduced into Iran's routine immunization program. Here, we report a systematic literature review of studies regarding S. pneumoniae serotype distribution in clinical and carrier patients in Iran. MEDLINE (via PubMed), Scopus, Embase, Ovid, Google Scholar, Web of Science, and the Iranian Database were used to identify relevant papers published from 1 January 2000 to 21 August 2019. The search returned 8 relevant articles. Among serotypes causing invasive pneumococcal diseases (IPD), serotype 23F (16.4%) was the most circulating serotype followed by 19F (15.2%), 19A (11.3%), 6A/B (9.2%), 9 V (5.8%), and 11A (5.14%). In carrier patients, the most common serotypes were, in rank order, 6A/B (10%), 19F (9%), 14(6.2%), 17F (4.8%), and 20(4.5%). Vaccine coverage among IPD patients would be 67.1% for PCV10-TT and 73.8% for PCV13. The present review demonstrates that the serotypes which were most responsible for disease in Iran are included in PCV10-TT and PCV13. However, sentinel surveillance must be continued in representative parts of the country to assess changing trends in the distribution of pneumococcal serotypes and their implications for vaccine selection and rollout in Iran.

Molecular characterization, antibiotic resistance pattern and capsular types of invasive Streptococcus pneumoniae isolated from clinical samples in Tehran, Iran

Background

Streptococcus pneumoniae causes serious infections worldwide. The aim of this study was to determine the molecular characteristic, antibiotic resistance pattern and capsular types of invasive S. pneumoniae in Tehran, Iran.

Results

Of the 44 pneumococcal invasive isolates, 39 (89%) were isolated from children and 5 (11%) from adults. The results show that all pneumococcal isolates were susceptible to linezolid but had varying resistance to trimethoprim-sulfamethoxazole (86%), erythromycin (73%), tetracycline (66%), clindamycin (43%), penicillin (16%), chloramphenicol (14%) and levofloxacin (2%). The range of erythromycin, tetracycline and penicillin MICs were 2 - ≥ 256 μg/mL, 4 - ≥ 48 μg/mL, and 0.047 - ≥ 256 respectively. All of the penicillin resistant isolates were multidrug resistant (MDR) and in addition to penicillin were resistant to tetracycline, erythromycin and trimethoprim-sulfamethoxazole. The most common capsular types detected in 64% of the pneumococcal isolates was 6A/B, 19A, 15A, 23F. The multilocus sequence typing (MLST) of 10 pneumococcal isolates revealed 9 different sequence types (STs), including ST 15139 (capsular type 19A) and ST 15140 (capsular type 23F), which have not previously been reported.

Conclusions

The study revealed that the S. pneumoniae isolates belonged to diverse capsular types and clones with high rate of resistance to erythromycin, tetracycline, and penicillin.

Molecular Detection and Serotyping of Streptococcus pneumoniae in Children with Suspected Meningitis in Northeast Iran

Background:

To date, more than 90 Streptococcus pneumoniae (S. pneumoniae) capsular serotypes are known. The prevalence of these serotypes varies according to the geographical area and the regional vaccination program. Due to the lack of regular vaccination programs for S. pneumoniae in developing countries, serotyping of the prevalent isolates is useful in selecting the correct vaccine. The present study aimed to evaluate common serotypes of pneumococcal meningitis in Bojnurd, Iran.

Methods:

All cerebrospinal fluid (CFS) samples suspected for bacterial meningitis were analyzed. The samples were collected during 2014-2018 in the Laboratory of Imam Reza Hospital (Bojnurd, Iran). Due to the high rate of false-negative cultures, polymerase chain reaction (PCR) was used for the detection of lytA and psaA genes of S. pneumoniae. In addition, the modified Marimon’s PCR method was used for serotyping the bacteria. The data were analyzed using Pearson’s Chi-square test.

Results:

Out of the 901 CSF samples, 106 cases tested positive for S. pneumoniae using the PCR method, while only 92 cases tested positive using the conventional methods. Based on the Marimon’s PCR method, serotypes 23F, 19F, 19A, 1, 14, and serogroup 6A/B were the most common types. Serogroups 18C, 15A/F, 15B/C, 9A/V, 7A/F, 11A/D/F, and 22A/F were also detected in isolates. Note that 2.8% of the samples were non-typable (NT).

Conclusion:

The results showed that only 13 serotypes were responsible for all meningitis cases. Pneumococcal capsular vaccine-13 (PCV-13) is the preferred choice against common serotypes of S. pneumoniae in northeast Iran.

The abstract was presented in Iran’s 19^th International Congress of Microbiology, as a poster and published in the congress abstracts book.

Serotype Distribution and Antibiotic Susceptibility of Streptococcus pneumoniae Isolates in Tehran, Iran: A Surveillance Study

Introduction

Encapsulated Streptococcus pneumoniae strains cause high morbidity and mortality, mainly in countries with no pneumococcal conjugate vaccines (PCVs) immunization program. This study investigated the epidemiological changes of S. pneumoniae isolates including serotype distribution and antimicrobial susceptibility in Tehran, Iran.

Methods

A total of 80 S. pneumoniae samples were collected from patients admitted to Shariati hospital over two periods. Half of the isolates were collected from February to September 2017 and the other half from July 2018 to March 2019. The antimicrobial susceptibility testing and PCV-13 serotype coverage of S. pneumoniae isolates were evaluated among patients with invasive and non-invasive infections.

Results

The most common serotypes were 23F (17.5%), 14 (16.3%), 3 (16.3%) 19F (12.5%), and 19A (12.5%) in the present study. The vaccine coverage rates of PCV-7, PCV-10 and PCV-13 were 52.6%, 52.6%, and 83.7%, respectively. S. pneumoniae isolates with the serotype of the PCV-13 showed an increasing trend during the study. Nearly half of the S. pneumoniae strains were MDR, while MDR serotype 19A increased (40%) during the study periods. A small minority of isolates (16%) belonged to non-vaccine serotypes, 65% of which were assigned to MDR. In general, the frequency of penicillin resistant and MDR strains were estimated about 27.5% and 51%, respectively. An increase was observed in resistance to erythromycin and co-trimoxazole.

Conclusion

The results showed that majority of the circulating serotypes in our study are related to PCV-13 serotypes. The use of conjugate vaccine in the immunization program and surveillance of antimicrobial resistance can be effective in reducing the pneumococcal clinical burden.

Antimicrobial susceptibility among Streptococcus pneumoniae and Haemophilus influenzae collected globally between 2015 and 2017 as part of the Tigecycline Evaluation and Surveillance Trial (TEST)

Purpose: In order to understand the prevalence of Streptococcus pneumoniae and Haemophilus influenzae globally and provide the basis for rational use of antimicrobials in clinical settings, in vitro activity of tigecycline and comparative agents was evaluated against 3929 S. pneumoniae and 4043 H. influenzae isolates obtained from 150 centers globally between 2015 and 2017 as a part of the Tigecycline Evaluation and Surveillance Trial (TEST). Methods: Broth microdilution methods were performed to determine the minimum inhibitory concentration (MIC) of the isolates according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI). The CLSI breakpoint was used to determine antimicrobial susceptibilities, except for that of tigecycline, for which the US Food and Drug Administration (FDA) breakpoints were used. Results: More than 99% of S. pneumoniae isolates were susceptible to vancomycin (100%), linezolid (100%), tigecycline (99.9%), and levofloxacin (99.1%). Macrolides (erythromycin, azithromycin, and clarithromycin, 67.1-69.4% susceptibility globally) and penicillin (61.7% in globally) were the drugs with more resisitance to S. pneumoniae. Penicillin-intermediate and -resistant isolates were found in 24.8% and 13.6% of S. pneumoniae isolates. H. influenzae was highly susceptible (>98.7%) to all antibiotics tested except for ampicillin, for which susceptibility was 76.1%. The number of drugs with the lowest susceptibility calculated in Asia were far more than other regions, with 61.5% (8 in 13 drugs) in S. pneumoniae and 70.0% (7 in 10 drugs) in H. influenzae, respectively. Conclusions: Vancomycin, linezolid, tigecycline, and levofloxacin can be used as the first choice in the empirical therapy of infection disease caused by S. pneumoniae. But macrolides and penicillin should be used prudently in treatment of the infection caused by S. pneumoniae, as well as ampicillin treat the infection caused by H. influenzae. Asia was the region with the most severe resistance in S. pneumoniae and H. influenzae.

Molecular Analysis of PBP1A in Streptococcus pneumoniae Isolated from Clinical and Normal Flora Samples in Tehran, Iran: A Multicenter Study

The emergence of high-level penicillin resistance in pneumococcal isolates has seriously complicated the treatment of pneumococcal infections in recent years. The purpose of this study was to determine the serotype, antimicrobial susceptibility, molecular typing, and genetic analysis of the penicillin-binding protein 1a (pbp1a) gene in pneumococcal isolates with high-level resistance to penicillin in Tehran, Iran. PCR amplification, sequencing, and data analysis of the pbp1a gene were carried out for isolates with high-level resistance to penicillin. Antibiotic susceptibility tests showed that the multiple drug resistance pattern "E-CD-OX-TS-T" was the most prevalent (18.0%). The most common serotypes were serotypes 14 (21%), 19F (17%), 23F (16%), and 3 (16%). The highest mutation rates were found in STMK conserved motifs, but no mutation was detected in the other two sequence motifs (SRN and KTG). High-level resistant isolates showed mutations at residues TSQF (574-577) NTGY. Pneumococcal isolates have experienced shifts toward higher penicillin minimal inhibitory concentration levels and other β-lactams. The results of this study show that the presence of multiple substitutions in the pbp1a gene in pneumococcal isolates is highly associated with a reduced affinity to penicillin.

Clinical usefulness and accuracy of polymerase chain reaction in the detection of bacterial meningitis agents in pediatric cerebrospinal fluid

Bacterial meningitis poses enormous healthcare challenges due to a high mortality, morbidity and sequelae. Neisseria (N.) meningitidis, Haemophilus (H.) influenzae, Streptococcus (S.) pneumoniae and S. agalactiae remain among the most prevalent infectious agents that cause bacterial meningitis in children. The objective of this study was the simultaneous detection of these pathogens in suspected cerebrospinal fluid (CSF) by using multiplex polymerase chain reaction (mPCR) and compare PCR results with standard diagnostics currently used in clinical practice. CSF specimens were obtained from 515 children (<5 years) clinically suspected of having acute bacterial meningitis. Based on bacterial culture, four isolates of salmonella sp and one Citrobacter freundii isolate were identified. The remaining 510 CSF specimens, having negative culture, were subjected to mPCR. Twenty-three (4.51%) CSF samples yielded a PCR positive signal. The pathogens identified were: S. pneumoniae (n=13), H. influenzae (n=7) and N. meningitidis (n=3). S. agalactiae was not detected. Using sequential multiplex PCR, serogrouping of S. pneumoniae revealed 3 different serotypes: serotype 19A (n=6), 19F (n=4) and serotype 23F (n=3). Only the serotype A was identified for the 3N. meningitidis isolates. Despite vaccination, S. pneumoniae remains a leading cause of pediatric invasive disease. Detecting causative organism remains the most critical aspect for management of children with suspected meningitis. PCR method is more sensitive and rapid than culture for detecting the infectious agents. Institution of PCR diagnostics is recommended for early and appropriate therapy.