Bhatt Puneet, Tandel Kundan, Singh Alina, Kumar M, Grover Naveen, Sahni A K
Graded Specialist (Microbiology), Command Hospital (Southern Command), Pune 411040, India.
Graded Specialist (Microbiology), Defence Research & Development Establishment, Gwalior, India.
Med J Armed Forces India. 2016 Dec;72(Suppl 1):S54-S58. doi: 10.1016/j.mjafi.2016.03.007. Epub 2016 Jun 24.
Methicillin-resistant Coagulase-negative Staphylococci (MR-CoNS) have emerged as an important cause of nosocomial infections especially in patients with prosthetic devices and implants. This study was conducted with an aim to determine the prevalence of methicillin resistance among CoNS isolates at a tertiary care center by both phenotypic and genotypic methods.
This cross sectional study was carried out from September 2011 to February 2014 in which 150 non-repetitive clinical isolates of CoNS were identified at the species level by conventional phenotypic methods. Cefoxitin disk (30 μg) diffusion testing was used to determine methicillin resistance and confirmed by detection of A gene by polymerase chain reaction (PCR).
Out of 150 CoNS isolates, 51 were methicillin resistant by cefoxitin disk diffusion method. Out of these 51 isolates, A gene was detected only in 45 isolates. Moreover, A gene was also detected in 4 isolates, which were cefoxitin sensitive. Thus, the prevalence of methicillin resistance among CoNS was found to be 32.7% by PCR.
The prevalence of methicillin resistance among Coagulase-negative Staphylococci (CoNS) was 32.7% by PCR detection of A gene. The sensitivity and specificity of cefoxitin disk diffusion method against A gene detection by PCR were found to be more than 90%. It can be concluded from this study that cefoxitin disk diffusion test can be used as a useful screening method to detect methicillin resistance among CoNS isolates. However, detection of A gene by PCR remains a more accurate method of detecting methicillin resistance among CoNS.
耐甲氧西林凝固酶阴性葡萄球菌（MR-CoNS）已成为医院感染的重要原因，尤其是在使用假体装置和植入物的患者中。本研究旨在通过表型和基因型方法确定三级护理中心凝固酶阴性葡萄球菌（CoNS）分离株中甲氧西林耐药性的流行情况。
本横断面研究于2011年9月至2014年2月进行，通过传统表型方法在种水平上鉴定了150株非重复性CoNS临床分离株。采用头孢西丁纸片（30μg）扩散试验确定甲氧西林耐药性，并通过聚合酶链反应（PCR）检测A基因进行确认。
在150株CoNS分离株中，通过头孢西丁纸片扩散法检测到51株对甲氧西林耐药。在这51株分离株中，仅在45株中检测到A基因。此外，在4株对头孢西丁敏感的分离株中也检测到了A基因。因此，通过PCR检测发现CoNS中甲氧西林耐药性的流行率为32.7%。
通过PCR检测A基因，凝固酶阴性葡萄球菌（CoNS）中甲氧西林耐药性的流行率为32.7%。发现头孢西丁纸片扩散法相对于通过PCR检测A基因的敏感性和特异性均超过90%。从本研究可以得出结论，头孢西丁纸片扩散试验可作为检测CoNS分离株中甲氧西林耐药性的有用筛查方法。然而，通过PCR检测A基因仍然是检测CoNS中甲氧西林耐药性更准确的方法。
