Genotypic and phenotypic characteristics of Streptococcus pneumoniae from community-acquired pneumonia patients and healthy asymptomatic participants in Sichuan province, China

Shihui Peng,Changguo Gu,Xin Huang,Yinan Li,Qun Li,Linzi Zeng,Hongyu Ren,Nianli Zou,Haiying Chen,Ming Li,Jianping Deng,Longze Luo,Qiwu Yuan,Na Zhao,Zheng Liao,Zhengdong Zhang,Tian Qin,Shenen Chen,Bin Wang

doi:10.1186/s12879-021-06737-w

Abstract

BackgroundStreptococcus pneumoniae (S. pneumoniae) is the common cause of community-acquired pneumonia (CAP) and is also found in the upper respiratory tract of healthy people. Hence, the study aimed to compare the serotypes, virulence/pili genes, and antibiotic susceptibility of S. pneumoniae from healthy asymptomatic participants and CAP patients.MethodsStreptococcus pneumoniae were retrospectively collected from health asymptomatic participants and CAP patients in Sichuan, China. The serotypes were tested by multiplex polymerase chain reaction (PCR) or Quellung reaction. Antibiotic susceptibility testing was performed using the broth microdilution method. The molecular epidemiology of S. pneumoniae was analyzed by multilocus sequence typing (MLST). Additionally, the presence of virulence/pili genes were detected using PCR.ResultsA total of 83 pneumococcal isolates were collected in the current study. Of these, 52 and 31 isolates were from healthy asymptomatic participants and CAP patients, respectively. Most of S. pneumoniae were resistant to erythromycin (ERY), clindamycin (CLI), tetracycline (TET) and trimethoprim-sulfamethoxazole (SXT). 90.4% isolates were classified as multidrug resistant (MDR). The predominant serotypes were 3, 19F and 19A in the CAP carriers, whereas 3, 6 and 19F were the main serotypes among the asymptomatic carriers. The overall coverage rates of pneumococcal conjugate vaccine (PCV) 10 and PCV13 serotypes were 34.9% and 66.3%, respectively. The predominant sequence types (STs) were ST271, ST320, and ST3397. There were significant differences in some resistance and virulence characteristics between CAP patients and asymptomatic carriers. Additionally, clonal complex (CC) 271 strains had higher percentage in resistance to cefuroxime (CXM) and cefotaxime (CEF), meropenem (MER) and cefepime (CFP), which mainly carried the rlrA and sipA genes.ConclusionsHigh coverage rate of PCV13 and high prevalence of MDR indicated the necessity to expand immunization with PCV13 and rationally use the antibiotics in Sichuan, China. Importantly, long-term surveillance should be conducted to assess effectiveness brought by vaccines. Our findings may supply new guidance for developing new pneumococcal vaccines.

Highlights

Streptococcus pneumoniae (S. pneumoniae) is the common cause of community-acquired pneumonia (CAP) and is found in the upper respiratory tract of healthy people
A total of 83 pneumococcal isolates were obtained from 598 healthy asymptomatic participants and 600 CAP patients
31 S. pneumoniae (5.2%) were obtained from CAP patients. 17 isolates of S. pneumonia were from male (54.8%) and 14 from female (45.2%)

Summary

Introduction

Streptococcus pneumoniae (S. pneumoniae) is the common cause of community-acquired pneumonia (CAP) and is found in the upper respiratory tract of healthy people. The study aimed to compare the serotypes, virulence/pili genes, and antibiotic susceptibility of S. pneumoniae from healthy asymptomatic participants and CAP patients. Community-acquired pneumonia (CAP) is an infection of lung parenchyma that occurs in persons outside the hospital, which has high rates of morbidity and mortality, especially in children and elderly [1, 2]. Previous study has stated that the multidrug resistance of S. pneumoniae in China was the highest among the 11 Asian countries [7], indicating the urgent needs for controlling antimicrobial resistance. Capsular polysaccharides as virulence factors, are the basis of S. pneumoniae vaccines, including the 7-valent pneumococcal conjugate vaccine (PCV7), the 10-valent PCV (PCV10), and the 13-valent PCV (PCV13) [10]. A previous study has stated that serotype distribution varies in Asian countries, and non-PCV serotypes have emerged as well [12]. Monitoring local serotypes can prevent the occurrence of pneumococcal disease and provide the guidance for developing new pneumococcal vaccines

Methods

Results

Discussion

Conclusion