Population structure of invasive Streptococcus pneumoniae isolates among Alaskan children in the conjugate vaccine era, 2001 to 2013

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.

Multi-Locus Sequence Typing and Drug Resistance Analysis of Swine Origin Escherichia coli in Shandong of China and Its Potential Risk on Public Health

The extensive use of antibiotics has caused antimicrobial resistance and multidrug resistance in Escherichia coli and gradual expands it into a worldwide problem. The resistant E. coli could be transmitted to humans through animal products, thereby creating a problem for bacterial treatment in humans and resulting in a public health issue. This study aims to investigate the molecular typing and drug resistance of swine and human origin E. coli within the same prefecture-level cities of Shandong Province and the potential risk of E. coli on public health. The drug sensitivity results indicated that tetracycline (TE) (97.17%) is a major antibiotic with high drug resistance in 106 swine origin E. coli. There was a significant difference in the drug-resistant genotypes between the two sources, of which the blaTEM positive rate was the highest in the genera of β-lactams (99% in swines and 100% in humans). Among the 146 E. coli isolates, 98 (91.51% swine origin) and 31 (77.5% human origin) isolates were simultaneously resistant to three or more classes of antibiotics, respectively. The multi-locus sequence typing (MLST) results indicate that the 106 swine origin E. coli isolates are divided into 25 STs with ST1258, ST361, and ST10 being the dominant sequence analysis typing strains. There were 19 MLST genotypes in 40 strains of human E. coli from Tai'an, Shandong Province, with ST1193, ST73, ST648, ST131, ST10, and ST1668 being the dominant strains. Moreover, the cluster analysis showed that CCl0 and CC23 were the common clonal complexes (CCs) from the two sources. Our results provide a theoretical basis for guiding the rational use of antibiotics and preventing the spread of drug-resistant bacteria, and also provide epidemiological data for the risk analysis of foodborne bacteria and antimicrobial resistance in swine farms in Shandong Province.

Molecular characterization and epidemiology of Streptococcus pneumoniae serotype 8 in Denmark

Background

Streptococcus pneumoniae serotype 8 incidence has increased in Denmark after the introduction of pneumococcal conjugated vaccines (PCV). The mechanism behind the serotype 8 replacement is not well understood. In this study, we aimed to present epidemiological data on invasive pneumococcal disease (IPD) and molecular characterization of 96 serotype 8 clinical isolates.

Methods

IPD data from 1999 to 2019 were used to calculate the incidence and age distribution. Whole-genome sequencing (WGS) analysis was performed on 96 isolates (6.8% of the total serotype 8 IPD isolates in the period) to characterize the isolates with respect to pneumococcal lineage traits, a range of genes with potential species discrimination, presence of colonization and virulence factors, and molecular resistance pattern.

Results

The serotype 8 IPD incidence increased significantly (P < 0.05) for the age groups above 15 years after the introduction of PCV13, primarily affecting the elderly (65+). All isolates were phenotypically susceptible to penicillin, erythromycin and clindamycin.

Molecular characterization revealed seven different MLST profiles with ST53 as the most prevalent lineage (87.5%) among the analyzed serotype 8 isolates. The genes covering the cell-surface proteins: lytA, rspB, pspA, psaA & Xisco and the pneumococcal toxin pneumolysin = ply were present in all isolates, while genes for the membrane transporter proteins: piaA/piaB/piaC; the capsular genes: cpsA (wzg) & psrP; the metallo-binding proteins zmpB & zmpC; and the neuroamidase proteins: nanA/nanB were variably present. Surprisingly, the putative transcriptional regulator gene SP2020 was not present in all isolates (98%). Susceptibility to penicillin, erythromycin and clindamycin was molecularly confirmed.

Conclusion

The observed serotype 8 replacement was not significantly reflected with a change in the MLST profile or changes in antibiotic resistance- or virulence determinants.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06103-w.

Molecular characterization of Latin American invasive Streptococcus pneumoniae serotype 19A isolates

Streptococcus pneumoniae is a major cause of morbidity and mortality worldwide, especially among children and the elderly. S. pneumoniae serotype 19A has emerged as a major cause of invasive disease in many countries, regardless of whether pneumococcal conjugate vaccines are used. The aim of this study was molecular characterization of invasive S. pneumoniae serotype 19A isolates recovered between 2000 and 2015 from 13 National Laboratories through the laboratory-based surveillance of invasive S. pneumoniae program SIREVA II in Latin American countries. The isolates were submitted with antimicrobial susceptibility tests and were genotyped by a combination of pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Of the 185 isolates assayed, notable rates of resistance to penicillin (MIC ≥ 0.125 µg/mL; 68.6%), tetracycline (63.7%), trimethoprim-sulfamethoxazole (63.2%), and erythromycin (43.2%) were observed, while 44.3% of isolates were multidrug resistant. The most frequently observed sequence types (ST) were ST320 (32.4%), ST199 (14.1%), ST172 (10.8%) and ST5204 (7.1%). The distribution of STs indicated regional differences in the epidemiology of the clonal groups. The present study showed a diverse genetic background of the pneumococcal population in Latin American countries. Continuous surveillance of the pneumococcal serotype 19A population in the region will be necessary to obtain information about geographical differences and changes in the spread and the establishment of particular clones.

The impact of routine childhood immunization with higher-valent pneumococcal conjugate vaccines on antimicrobial-resistant pneumococcal diseases and carriage: a systematic literature review

Introduction: The introduction of 7-valent pneumococcal conjugate vaccine (PCV7) in childhood immunization programs reduced antimicrobial-resistant pneumococcal infections by vaccine serotypes. However, emerging antimicrobial-resistant non-vaccine serotypes, particularly serotype 19A, attenuated the overall effect. In 2010, higher-valent PCVs became available containing serotypes that are prone to become antimicrobial-resistant, like serotype 7F in PCV10 and PCV13, and serotype 19A in PCV13.Areas covered: This review evaluated literature published between June 1, 2008 and June 1, 2017 reporting on the effect of PCV10 or PCV13 implementation in routine infant immunization schedules on antimicrobial-resistant invasive pneumococcal disease (IPD), otitis media (OM), and nasopharyngeal carriage (NPC) in children and adults.Expert opinion: In countries with relatively high prior pneumococcal antimicrobial resistance (AMR), PCV13 childhood vaccination programs have reduced antimicrobial-resistant IPD, OM, and NPC in children and IPD in adults. The effectiveness of PCV13 against serotype 19A is likely an important contributing factor. Only few studies have documented the impact of PCV10 on AMR. Multiple factors may influence observed decreases in pneumococcal AMR including antimicrobial stewardship, case definition, time since PCV10/13 introduction, and pre-PCV10/13 AMR levels. This review emphasizes the importance of including impact on AMR when evaluating the full public health of pneumococcal vaccination programs.