Zhongyi Lu1, Yong Chen2, Wei Chen3, Hui Liu4, Qing Song4, Xiaofeng Hu2, Ziying Zou5, Zhengxiang Liu6, Libo Duo7, Jiyong Yang8, Yanwen Gong9, Zhanke Wang10, Xuqin Wu11, Jingya Zhao2, Changjian Zhang2, Mengqiang Zhang2, Li Han12. 1. Center for Hospital Infection Control, Chinese PLA Institute for Disease Control & Prevention, Academy of Military Medical Sciences, Beijing, China College of Food Science and Engineering, Shandong Agricultural University Shandong Agricultural University, Tai'an, China. 2. Center for Hospital Infection Control, Chinese PLA Institute for Disease Control & Prevention, Academy of Military Medical Sciences, Beijing, China. 3. College of Food Science and Engineering, Shandong Agricultural University Shandong Agricultural University, Tai'an, China. 4. Department of Surgical Intensive Care Unit, Chinese PLA General Hospital, Beijing, China. 5. Department of Clinical Laboratory, General Hospital of Chengdu Military Command, Chengdu, China. 6. Department of Clinical Microbiology, Urumqi General Hospital of Lanzhou Military Command, PLA, Urumqi, China. 7. Department of Clinical Microbiology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China. 8. Department of Clinical Microbiology, Chinese PLA General Hospital, Beijing, China. 9. Department of Clinical Laboratory, General Hospital of Ji'nan Military Command, Ji'nan, China. 10. Department of Clinical Laboratory, 94 Hospital of PLA, Nanchang, China. 11. Department of Clinical Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, China. 12. Center for Hospital Infection Control, Chinese PLA Institute for Disease Control & Prevention, Academy of Military Medical Sciences, Beijing, China hanlicdc@163.com.
Abstract
OBJECTIVES: This study was designed to demonstrate the characteristics of qacA/B-positive Staphylococcus aureus in China. METHODS: One hundred and forty-five MRSA and 178 MSSA from clinical specimens from seven hospitals in different regions of China, 70 MRSA from superficial sites of patients and 106 MRSA from environmental samples from an ICU were collected and screened for the presence of the qacA/B gene. The qacA/B-positive isolates and 72 randomly selected qacA/B-negative control isolates were further characterized by MLST, spa typing and detection of toxin genes, as well as antimicrobial and chlorhexidine susceptibility. SCCmec typing was conducted for MRSA. PFGE was conducted for qacA/B-positive isolates. RESULTS: Twenty-five (7.8%) of the 321 MRSA isolates harboured qacA/B, including 11 isolates from clinical specimens (7.6%), 12 isolates from patients' superficial sites (17.1%) and 2 isolates from an ICU environment (1.9%). Ten and five qacA/B-positive MRSA were identified as ST239-t030-MRSA-III and ST239-t037-MRSA-III, respectively. Six PFGE clusters and five singletons were identified among the 25 qacA/B-positive MRSA. Only one (0.6%) of the 178 MSSA isolates harboured qacA/B. qacA/B carriage in MRSA was statistically associated with spa-t037 and the presence of mupA. Compared with qacA/B-negative MRSA, the qacA/B-positive MRSA exhibited a lower susceptibility to chlorhexidine and higher resistance rates to clindamycin and trimethoprim/sulfamethoxazole. CONCLUSIONS: Carriage of qacA/B, although it had a low prevalence, might be the main reason for declining susceptibility to chlorhexidine in MRSA from Chinese patients and is probably associated with spa-t037 and the presence of the mupA gene.
OBJECTIVES: This study was designed to demonstrate the characteristics of qacA/B-positive Staphylococcus aureus in China. METHODS: One hundred and forty-five MRSA and 178 MSSA from clinical specimens from seven hospitals in different regions of China, 70 MRSA from superficial sites of patients and 106 MRSA from environmental samples from an ICU were collected and screened for the presence of the qacA/B gene. The qacA/B-positive isolates and 72 randomly selected qacA/B-negative control isolates were further characterized by MLST, spa typing and detection of toxin genes, as well as antimicrobial and chlorhexidine susceptibility. SCCmec typing was conducted for MRSA. PFGE was conducted for qacA/B-positive isolates. RESULTS: Twenty-five (7.8%) of the 321 MRSA isolates harboured qacA/B, including 11 isolates from clinical specimens (7.6%), 12 isolates from patients' superficial sites (17.1%) and 2 isolates from an ICU environment (1.9%). Ten and five qacA/B-positive MRSA were identified as ST239-t030-MRSA-III and ST239-t037-MRSA-III, respectively. Six PFGE clusters and five singletons were identified among the 25 qacA/B-positive MRSA. Only one (0.6%) of the 178 MSSA isolates harboured qacA/B. qacA/B carriage in MRSA was statistically associated with spa-t037 and the presence of mupA. Compared with qacA/B-negative MRSA, the qacA/B-positive MRSA exhibited a lower susceptibility to chlorhexidine and higher resistance rates to clindamycin and trimethoprim/sulfamethoxazole. CONCLUSIONS: Carriage of qacA/B, although it had a low prevalence, might be the main reason for declining susceptibility to chlorhexidine in MRSA from Chinese patients and is probably associated with spa-t037 and the presence of the mupA gene.