Molecular characteristics and antimicrobial susceptibility of Staphylococcus aureus among children with respiratory tract infections in southwest China
The molecular characteristics and antimicrobial susceptibility of Staphylococcus aureus (S. aureus) in general pediatric wards and county-level hospitals were rarely reported in China.
Staphylococcus aureus was isolated from children hospitalized with respiratory tract infection (RTI) in Zhongjiang and Youyang counties in 2015. All isolates were typed by multilocus sequence, staphylococcal protein A, accessory gene regulator (agr), and staphylococcal cassette chromosome mec [SCCmec, for methicillin-resistant S. aureus (MRSA) only]. Polymerase chain reaction was used to screen 21 super-antigen (SAg) genes and panton–valentine leukocidin (pvl). Antimicrobial susceptibility testing was performed by E test.
A total of 2136 children were enrolled. Overall, 125 (5.9%) children carried S. aureus, among which MRSA accounted for 42.4%. ST59-SCCmec type IV-t437-agr group I (58.5%) was the most prevalent genotype in MRSA, and ST188-t189-agr group I (22.2%) was the top genotype in methicillin-sensitive S. aureus (MSSA). The pvl carriage rate in MRSA and MSSA was 15.1% and 9.7%, respectively (P = 0.4112). About 96.8% of S. aureus isolates were positive for at least one SAg gene. The most common SAg gene profile in the dominant ST59 clone was seb–sek–seq (42.8%). All S. aureus isolates were resistant to penicillin and erythromycin (minimum inhibitory concentration 90 was > 32 and 256 mg/L to penicillin and erythromycin, respectively), but usually susceptible to other tested non-β-lactam antimicrobials.
Staphylococcus aureus and MRSA were detected with a high frequency in children with RTI in county-level hospitals of China. ST59-SCCmec type IV-t437-agr group I was the dominant MRSA clone. The S. aureus isolates exhibited high resistance to penicillin and erythromycin.
KeywordsAntimicrobial susceptibility Chinese children Molecular characteristics Staphylococcus aureus
We are very grateful to the local clinical laboratory staff, Ping Tang, Hai-Ling Zeng in People's Hospital of Zhongjiang County and Xiao-Ping Cheng in Youyang Hospital, respectively, who kindly helped us in treating and storing the clinical isolates. We also thank pediatricians in the two hospitals involved in collecting the samples.
SYQ and KHY designed the study, reviewed and revised the manuscript. CS and QW conducted the experiments and wrote the manuscript, and contributed equally to this work. WTL, XY, WS and QHM oversaw data analysis planning and execution. DNW and CHC designed the data collection instruments and coordinated sample collection. All authors read and approved the final manuscript.
This work was supported by the National Natural Science Foundation of China (No. 81571948) and the Beijing Natural Science Foundation (No. 7172075), the medical research project of Chongqing Health and Family Planning Commission (No. 2016ZDX041).
Compliance with ethical standards
This study was approved by the Ethics Committee of Beijing Children’s Hospital Affiliated to Capital Medical University. Written informed consents were obtained from the patients’ legal guardian.
Conflict of interest
The authors declare that they have no competing interests.
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