Pai Vidya, Rao Venkatakrishna I, Rao Sunil P
Department of Microbiology, Yenepoya Medical College, Nithyananda Nagar, Mangalore - 575 018, India.
J Lab Physicians. 2010 Jul;2(2):82-4. doi: 10.4103/0974-2727.72155.
BACKGROUND/AIM: Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of nosocomial infections worldwide. The aim of this study was to determine the prevalence of MRSA and their antimicrobial susceptibility pattern in our hospital located in Mangalore, India.
The bacterial isolates from various clinical specimens of patients admitted in our hospital were cultured as per standard protocol and all isolates of Staphylococcus aureus obtained were included in the study. The isolates were identified by standard methods like catalase test, slide and tube coagulase tests, and growth on Mannitol salt agar (HiMedia Lab, Mumbai). The antimicrobial susceptibility testing was performed by Kirby-Bauer disc diffusion method. The D-test for inducible clindamycin resistance was performed. The isolates were tested for methicillin resistance by using oxacillin disc by disc diffusion method and confirmed by agar screen test (oxacillin 6 μgm/ml). The results were interpreted according to CLSI criteria.
During a period of one year, a total of 237 isolates of S. aureus were studied and 69 (29.1%) were found to be methicillin-resistant. MRSA isolates showed greater resistance to multiple drugs than methicillin sensitive Staphylococcus aureus MSSA isolates. Inducible clindamycin resistance was 18.8% in MRSA as against 3.5% in MSSA. About 40-50% of MRSA were resistant to erythromycin, gentamicin, and chloramphenicol, while less than 30% were resistant to ciprofloxacin and amikacin. However, all strains were sensitive to vancomycin.
The regular surveillance of hospital-acquired infections of MRSA may be helpful in formulating and monitoring the antibiotic policy. This may also help in preserving antibiotics like vancomycin, only for life-threatening staphylococcal diseases.
背景/目的：耐甲氧西林金黄色葡萄球菌（MRSA）是全球医院感染的重要原因。本研究的目的是确定位于印度芒格洛尔的我院MRSA的流行情况及其抗菌药敏模式。
按照标准方案对我院收治患者的各种临床标本中的细菌分离株进行培养，所有获得的金黄色葡萄球菌分离株均纳入研究。通过过氧化氢酶试验、玻片和试管凝固酶试验以及在甘露醇盐琼脂（HiMedia实验室，孟买）上生长等标准方法对分离株进行鉴定。采用 Kirby-Bauer 纸片扩散法进行抗菌药敏试验。进行诱导型克林霉素耐药的D试验。通过纸片扩散法使用苯唑西林纸片对分离株进行耐甲氧西林检测，并通过琼脂筛选试验（苯唑西林6μg/ml）进行确认。结果根据CLSI标准进行解释。
在一年的时间里，共研究了237株金黄色葡萄球菌分离株，发现69株（29.1%）为耐甲氧西林菌株。MRSA分离株比甲氧西林敏感金黄色葡萄球菌（MSSA）分离株对多种药物表现出更高的耐药性。MRSA中诱导型克林霉素耐药率为18.8%，而MSSA中为3.5%。约40 - 50%的MRSA对红霉素、庆大霉素和氯霉素耐药，而对环丙沙星和阿米卡星耐药的不到30%。然而，所有菌株对万古霉素敏感。
对医院获得性MRSA感染进行定期监测可能有助于制定和监测抗生素政策。这也可能有助于仅将万古霉素等抗生素保留用于治疗危及生命的葡萄球菌疾病。
