Belbase Ankit, Pant Narayan Dutt, Nepal Krishus, Neupane Bibhusan, Baidhya Rikesh, Baidya Reena, Lekhak Binod
Department of Microbiology, GoldenGate International College, Battisputali, Kathmandu, Nepal.
Department of Microbiology, Grande International Hospital, Dhapasi, Kathmandu, Nepal.
Ann Clin Microbiol Antimicrob. 2017 Mar 23;16(1):15. doi: 10.1186/s12941-017-0194-0.
The increasing drug resistance along with inducible clindamycin resistance, methicillin resistance and biofilm production among the strains of Staphylococcus aureus are present as the serious problems to the successful treatment of the infections caused by S. aureus. So, the main objectives of this study were to determine the antimicrobial susceptibility patterns along with the rates of inducible clindamycin resistance, methicillin resistance and biofilm production among the strains of S. aureus isolated from pus/wound swab samples.
A total of 830 non-repeated pus/wound swab samples were processed using standard microbiological techniques. The colonies grown were identified on the basis of colony morphology, Gram's stain and biochemical tests. Antimicrobial susceptibility testing was performed by Kirby-Bauer disc diffusion technique. Detection of inducible clindamycin resistance was performed by D test, while detection of methicillin resistant S. aureus (MRSA) was performed by determination of minimum inhibitory concentration of oxacillin by agar dilution method. Similarly, detection of biofilm formation was performed by microtiter plate method. Strains showing resistance to three or more than three different classes of antibiotics were considered multidrug resistant.
Total 76 samples showed the growth of S. aureus, among which 36 (47.4%) contained MRSA and 17 (22.4%) samples were found to have S. aureus showing inducible clindamycin resistance. Among the S. aureus isolated from outpatients, 41.9% were MRSA. Highest rates of susceptibility of S. aureus were seen toward linezolid (100%) and vancomycin (100%). Similarly, S. aureus isolated from 35 (46.1%) samples were found to be biofilm producers. Higher rate of inducible clindamycin resistance was seen among MRSA in comparison to methicillin susceptible S. aureus (MSSA). Similarly, higher rates of multidrug resistance and methicillin resistance were found among biofilm producing strains in comparison to biofilm non producing strains.
The rate of isolation of MRSA from community acquired infections was found to be high in Nepal. Increased rate of inducible clindamycin resistance as compared to previous studies in Nepal was noted. So for the proper management of the infections caused by S. aureus, D test for the detection of inducible clindamycin resistance should be included in the routine laboratory diagnosis. Further, detection of biofilm production should also be included in the routine tests. Linezolid and vancomycin can be used for the preliminary treatment of the serious infections caused by S. aureus.
金黄色葡萄球菌菌株中耐药性的增加以及诱导型克林霉素耐药、耐甲氧西林和生物膜形成是成功治疗金黄色葡萄球菌感染的严重问题。因此，本研究的主要目的是确定从脓液/伤口拭子样本中分离出的金黄色葡萄球菌菌株的抗菌药敏模式以及诱导型克林霉素耐药、耐甲氧西林和生物膜形成的发生率。
使用标准微生物学技术处理了总共830份非重复的脓液/伤口拭子样本。根据菌落形态、革兰氏染色和生化试验对生长的菌落进行鉴定。采用 Kirby-Bauer 纸片扩散法进行抗菌药敏试验。通过D试验检测诱导型克林霉素耐药性，而通过琼脂稀释法测定苯唑西林的最低抑菌浓度来检测耐甲氧西林金黄色葡萄球菌（MRSA）。同样，采用微量滴定板法检测生物膜形成。对三种或三种以上不同类别的抗生素耐药菌株被视为多重耐药。
总共76份样本显示有金黄色葡萄球菌生长，其中36份（47.4%）含有MRSA，17份（约22.4%）样本中的金黄色葡萄球菌显示出诱导型克林霉素耐药。在从门诊患者中分离出的金黄色葡萄球菌中，41.9%为MRSA。金黄色葡萄球菌对利奈唑胺（100%）和万古霉素（100%）的敏感性最高。同样，从35份（46.1%）样本中分离出的金黄色葡萄球菌被发现是生物膜产生菌。与甲氧西林敏感金黄色葡萄球菌（MSSA）相比，MRSA中诱导型克林霉素耐药率更高。同样，与非生物膜产生菌株相比，生物膜产生菌株中的多重耐药和耐甲氧西林率更高。
在尼泊尔，社区获得性感染中MRSA的分离率较高。与尼泊尔以前的研究相比，诱导型克林霉素耐药率有所增加。因此，为了正确管理金黄色葡萄球菌引起的感染，在常规实验室诊断中应包括检测诱导型克林霉素耐药性的D试验。此外，生物膜形成的检测也应纳入常规检测。利奈唑胺和万古霉素可用于金黄色葡萄球菌引起的严重感染 的初步治疗。
