Population biology of 225 serogroup 6 Streptococcus pneumoniae isolates collected in China

Multiple-Drug Resistant Nasopharyngeal Streptococcus pneumoniae Isolated in Russia: Serotypes, Antimicrobial Susceptibility, and Molecular Characterization of the Emergent Serotype 13/ST2754 Lineage

The pneumococcal population structure and drug resistance patterns are constantly changing worldwide. In this study, we described serotypes and antimicrobial susceptibility among 478 multiple-drug resistant (MDR) pediatric nasopharyngeal pneumococci recovered in 2010-2017. The majority of isolates (89.3%; n = 427) carried pneumococcal conjugate vaccine (PCV)13 serotypes, predominantly 6A/B, 14, 19A/F, and 23F. A non-PCV13 serotype capsule was detected in 44 (9.2%) MDR pneumococci, including serotypes 23A (n = 8), 13 (n = 7), 28F (n = 6), 11A (n = 5), and serogroup 35 (n = 10) isolates. The remaining seven (1.5%) MDR isolates were nontypeable. The majority of non-PCV13-serotype isolates were resistant to tetracycline, erythromycin, and clindamycin; most harbored both the ermB and mef genes. Among the 44 serotyped MDR non-PCV13 isolates, multilocus sequence typing analysis revealed 24 different sequence types (STs). ST2754 was the most abundant lineage demonstrating an unusual association with serotypes 13 (n = 7) and 9N (n = 1). The whole-genome sequencing-based analysis demonstrated that the serotype 13/ST2754 lineage was closely related to the serotype 13/ST2754 isolate recovered in Africa (Malawi) in 2013, possessed a Tn6002-like transposon carrying the erm(B) and tet(M) genes, and harbored additional virulence determinants, including arginine metabolism genes and a putative bacteriocin locus. Such a favorable genetic background may provide competitive advantages and potential for spreading and expansion of this clone among pneumococci. These data warrant further molecular monitoring of the genetic composition of the changing pneumococcal population.

The use of PCR and BsmAI restriction combination targeting wciP gene to determine serotype 6A, 6B, 6C and 6D Streptococcus pneumoniae

We designed a sensitive and reliable method to distinguish serogroup 6 using PCR followed by enzymatic restriction digest. We discovered that this serotyping method was able to distinguish serotypes 6A, 6B, 6C, and 6D based on the recognition site of BsmAI in the wciP region.

Serotype distribution, antibiotic resistance patterns and molecular characteristics of serogroup 6 Streptococcus pneumoniae isolates collected from Chinese children before the introduction of PCV13

OBJECTIVES

Streptococcus pneumoniae is an important pathogen in infectious diseases worldwide, and serogroup 6 S. pneumoniae strains are very common in China. This study investigated the serotype distribution, antibiotic resistance patterns and molecular characteristics of 215 serogroup 6 S. pneumoniae isolates collected from hospitalised children in China during 2013-2016.

METHODS

Serotypes were determined using the Quellung reaction with antisera. Antibiotic resistance against 11 antimicrobials was tested by Etest or the disk diffusion method. Sequence types (STs) were assigned using multilocus sequence typing (MLST). Data analysis was performed with WHONET 5.6 software.

RESULTS

The percentages of serotype 6A, 6B, 6C and 6D among the 215 serogroup 6 isolates were 50.7% (109/215), 36.3% (78/215), 12.6% (27/215) and 0.5% (1/215), respectively. All isolates were susceptible to levofloxacin and were resistant to erythromycin. No isolate was resistant to parenteral penicillin, but the intermediate and resistant rates reached 72.6% (156/215) and 5.1% (11/215), respectively, based on the oral breakpoint. Sixty-seven STs were detected, with 14 STs being newly assigned. The most common clonal complexes (CCs) were CC3173 (26.5%; 57/215), CC9789 (13.5%; 29/215), CC90 (13.0%; 28/215) and CC902 (8.8%; 19/215), and the non-susceptibility rates of these four CCs against penicillin and cefuroxime (penicillin, 98.2%, 100%, 100% and 100%, respectively; cefuroxime, 98.2%, 100%, 96.4% and 94.7%, respectively) were higher than the overall level of serogroup 6 isolates (penicillin, 77.7%; cefuroxime, 70.2%).

CONCLUSIONS

Serotype 6A is the most common serotype of serogroup 6 S. pneumoniae strains in Chinese children, and different CCs/STs express diverse antibiotic resistance patterns.

A systematic review about Streptococcus Pneumoniae serotype distribution in children in mainland of China before the PCV13 was licensed

INTRODUCTION

Streptococcus pneumoniae (S. pneumoniae) is a major pathogen of infectious diseases in children. Surveillance of the distribution of pneumococcus serotypes is important for immunization strategies of pneumococcal polysaccharide conjugate vaccines (PCVs). Areas covered: This article is a systematic review of studies conducted from 2006 to 2016 that document serotypes of S. pneumoniae isolated from children less than 14 years old in the mainland of China. A total of 40 studies were included in this review. Serotypes 19F, 19A, 23F, 14 and 6B were the most common. Serotype prevalence and percentage varied by region and associated strains. The serotype coverage rate of PCV13 was higher than that of PCV10 due to the prevalence of serotype 19A, and there were no significant difference between the coverage rate of PCV13 and PPSV23. Expert commentary: To prevent Chinese children from S. pneumoniae infection, it is necessary for the universal immunization of PCV13 or develop new vaccines that include all the prevalent serotypes in China.

Long-Term Epidemiology of Streptococcus pneumoniae Serogroup 6 in a Region of Southern Europe with Special Reference to Serotype 6E

Streptococcus pneumoniae serotype 6E has recently been described, but its long-term epidemiology is not well known. From 1981–2013, 704 serogroup 6 clinical isolates were obtained in Gipuzkoa, Basque Country, Spain. All invasive and one in four non-invasive isolates were included. Overall, 75, 97, 51 and 45 serotypes 6A, 6B, 6C and 6E isolates, respectively, were detected. No serotype 6D isolates were identified. The prevalence of serotypes 6E and 6B, but not that of serotypes 6A and 6C, declined after the introduction of pneumococcal conjugate vaccines. Serotype 6E isolates showed the highest resistance rate. Most serotype 6E isolates were ST90.