Serotype Distribution, Antimicrobial Susceptibility, and Molecular Epidemiology of Streptococcus pneumoniae Isolated from Children in Shanghai, China.

Fen Pan,Chun Wang,Weichun Huang,Huihong Qin,Jin Tang,Shuzhen Xiao,Hong Zhang,Lizhong Han

doi:10.1371/journal.pone.0142892

Abstract

Objective Streptococcus pneumoniae is a common pathogenic cause of pediatric infections. This study investigated the serotype distribution, antimicrobial susceptibility, and molecular epidemiology of pneumococci before the introduction of conjugate vaccines in Shanghai, China.MethodsA total of 284 clinical pneumococcal isolates (270, 5, 4,3, and 2 of which were isolated from sputum, bronchoalveolar lavage fluid, blood, cerebral spinal fluid, and ear secretions, respectively) from children less than 14 years of age who had not been vaccinated with a conjugate vaccine, were collected between January and December in 2013. All isolates were serotyped by multiplex polymerase chain reaction or quellung reactions and antimicrobial susceptibility testing was performed using the broth microdilution method. The molecular epidemiology of S.pneumoniae was analyzed by multilocus sequence typing (MLST).ResultsAmong the 284 pneumococcal isolates, 19F (33.5%), 19A (14.1%), 23F (12.0%), and 6A (8.8%) were the most common serotypes and the coverage rates of the 7-, 10-, and 13-valent pneumococcal conjugate vaccines (PCV7, PCV10, and PCV13) were 58.6%, 59.4% and 85.1%, respectively. Antimicrobial susceptibility showed that the prevalence rates of S.pneumoniae resistance to penicillin were 11.3% (32/284). Approximately 88.0% (250/284) of the isolates exhibited multi-drug resistance. MLST analysis revealed a high level of diversity, with 65 sequence types (STs) among 267 isolates. Specifically, the four predominant STs were ST271 (24.3%, 65/267), ST320 (11.2%, 30/267), ST81 (9.7%, 26/267), and ST3173 (5.2%, 14/267), which were mainly associated with serotypes 19F, 19A, 23F, and 6A, respectively.ConclusionsThe prevalent serotypes among clinical isolates from children were 19F, 19A, 23F, and 6A and these isolates showed high resistance rates to β-lactams and macrolides. The Taiwan19F-14 clone played a predominant role in the dissemination of pneumococcal isolates in Shanghai, China. Therefore, continued and regional surveillance on pneumococcal isolates may be necessary.

Highlights

Streptococcus pneumoniae, an encapsulated Gram-positive bacterium, represents a prominent pathogen associated with various illnesses, ranging from self-limiting infections to life-threatening invasive diseases
Antimicrobial susceptibility showed that the prevalence rates of S. pneumoniae resistance to penicillin were 11.3% (32/284)
multilocus sequence typing (MLST) analysis revealed a high level of diversity, with 65 sequence types (STs) among 267 isolates

Summary

Introduction

Streptococcus pneumoniae, an encapsulated Gram-positive bacterium, represents a prominent pathogen associated with various illnesses, ranging from self-limiting infections to life-threatening invasive diseases. Based on differences in the capsular polysaccharide (cps), more than 90 serotypes of S. pneumoniae have been identified, but only a limited number of serotypes cause the majority of severe pneumococcal infections [3]. Considering the high incidence and severity of pneumococcal diseases, researchers are dedicated to exploring new and effective methods to prevent the dissemination of S.pneumoniae. Since 2000, three pneumococcal conjugate vaccines including 7-, 10-, and 13-valent conjugate vaccines (PCV7, PCV10, and PCV13), which target some serotypes of pneumococci, have been successively introduced for preventing invasive pneumococcal disease in numerous countries [4,5,6]. There has been a remarkable decrease in the incidence of pneumococcal diseases including invasive and noninvasive infections [6,7]

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