Gupta Gunjan, Tak Vibhor, Mathur Purva
Department of Laboratory Medicine, Jai Prakash Narain Apex Trauma Centre, All India Institute of Medical Sciences, New Delhi, India.
J Lab Physicians. 2014 Jan;6(1):1-6. doi: 10.4103/0974-2727.129082.
AmpC β-lactamases are clinically important cephalosporinases encoded on the chromosomes of many Enterobacteriaceae and a few other organisms, where they mediate resistance to cephalothin, cefazolin, cefoxitin, most penicillins, and β-lactamase inhibitor/β-lactam combinations. The increase in antibiotic resistance among Gram-negative bacteria is a notable example of how bacteria can procure, maintain and express new genetic information that can confer resistance to one or several antibiotics. Detection of organisms producing these enzymes can be difficult, because their presence does not always produce a resistant phenotype on conventional disc diffusion or automated susceptibility testing methods. These enzymes are often associated with potentially fatal laboratory reports of false susceptibility to β-lactams phenotypically. With the world-wide increase in the occurrence, types and rate of dissemination of these enzymes, their early detection is critical. AmpC β-lactamases show tremendous variation in geographic distribution. Thus, their accurate detection and characterization are important from epidemiological, clinical, laboratory, and infection control point of view. This document describes the methods for detection for AmpC β-lactamases, which can be adopted by routine diagnostic laboratories.
AmpC β-内酰胺酶是临床上重要的头孢菌素酶，由许多肠杆菌科细菌及其他一些微生物的染色体编码，可介导对头孢噻吩、头孢唑林、头孢西丁、大多数青霉素以及β-内酰胺酶抑制剂/β-内酰胺组合的耐药性。革兰氏阴性菌抗生素耐药性的增加是细菌如何获取、维持和表达可赋予对一种或多种抗生素耐药性的新遗传信息的一个显著例子。检测产生这些酶的微生物可能很困难，因为在传统的纸片扩散法或自动化药敏试验方法中，它们的存在并不总是产生耐药表型。这些酶在表型上通常与β-内酰胺类药物假敏感的潜在致命实验室报告相关。随着这些酶在全球范围内的出现、类型和传播速率的增加，对其进行早期检测至关重要。AmpC β-内酰胺酶在地理分布上表现出巨大差异。因此，从流行病学、临床、实验室和感染控制的角度来看，对其进行准确检测和鉴定很重要。本文档描述了可被常规诊断实验室采用的AmpC β-内酰胺酶检测方法。
