Molecular characterization and antimicrobial susceptibility of Streptococcus pneumoniae isolated from children hospitalized with respiratory infections in Suzhou, China.
BACKGROUND
Dissemination of antibiotic resistant clones is recognized as an important factor in the emergence and prevalence of resistance in pneumococcus. This study was undertaken to survey the antimicrobial susceptibility and serotypes distribution of pneumococci and to explore the circulating clones in hospitalized children in Suzhou, China.


METHODS
The pneumococci were isolated from the nasopharyngeal aspirates of children less than 5 years of age admitted to Soochow-University-Affiliated-Children's-Hospital with respiratory infections. The capsular serotypes were identified by multiplex polymerase chain reaction (PCR). Antimicrobial susceptibility was tested by E-test. The presence of ermB, mefA/E genes were detected by PCR and the genotypes were explored by Multilocus sequence typing (MLST).


RESULTS
From July 2012 to July 2013, a total of 175 pneumococcal isolates were collected and all strains were resistant to erythromycin and clindamycin, about 39.4% strains were non-susceptible to penicillin G. Overall, 174 (99.4%) isolates were resistant to ≥ 3 types of antibiotics. Serotypes 19F (28.1%), 6B (19.7%), 19A (18.0%), and 23F (17.4%) were the most common serotypes in all identified strains. The serotypes coverage of PCV7 and PCV13 were 71.9% and 89.9%, respectively. Four international antibiotic-resistant clones, including Taiwan19F-14 (n = 79), Spain23F-1(n = 25), Taiwan23F-15(n = 7) and Spain6B-2(n = 7), were identified. The Taiwan19F-14 clones have a higher non-susceptibility rate in β-lactams than other clones and non-clone isolates (p<0.001). In addition, 98.7% Taiwan19F-14 clones were positive of both ermB and mefA/E genes, compare to 33.3% in other clones and non-clone strains.


CONCLUSIONS
The spread of international antibiotic-resistant clones, especially Taiwan19F-14 clones, played a predominant role in the dissemination of antimicrobial resistant isolates in Suzhou, China. Considering the high prevalence of PCV7 serotypes and serotype 19A, the introduction of PCV13 may be a promising preventive strategy to control the increasing trend of clonal spread in China.
Department of Epidemiology, School of Public Health, Fudan University, Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China.
Qian
Q
Geng
Department of Epidemiology, School of Public Health, Fudan University, Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China.
Tao
T
Zhang
Soochow University Affiliated Children's Hospital, Suzhou, China.
Yunfang
Y
Ding
Soochow University Affiliated Children's Hospital, Suzhou, China.
Yunzhen
Y
Tao
Department of Epidemiology, School of Public Health, Fudan University, Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China.
Yuzun
Y
Lin
Soochow University Affiliated Children's Hospital, Suzhou, China.
Yunzhong
Y
Wang
Center for Global Health, Cincinnati Children's Hospital, Cincinnati, Ohio, United States of America.
Steven
S
Black
Department of Epidemiology, School of Public Health, Fudan University, Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China.
Genming
G
Zhao
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D044466:Asian People; D001426:Bacterial Proteins / Q000235:genetics; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D002981:Clindamycin / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004917:Erythromycin / Q000494:pharmacology; D005260:Female; D006760:Hospitalization; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D008780:Methyltransferases / Q000235:genetics; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000235:genetics / Q000382:microbiology; D012141:Respiratory Tract Infections / Q000188:drug therapy / Q000453:epidemiology / Q000235:genetics / Q000382:microbiology; D065288:Serogroup; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C117866:MefA protein, Streptococcus; C431304:MefE protein, Streptococcus pneumoniae; D008565:Membrane Proteins; D002981:Clindamycin; D004917:Erythromycin; D008780:Methyltransferases