Khurana Surbhi, Mathur Purva, Kapil Arti, Valsan Chithra, Behera Bijayini
Department of Laboratory Medicine, Jai Prakash Narayan Apex Trauma Centre, All India Institute of Medical Sciences, New Delhi 110029, India.
Department of Microbiology, All India Institute of Medical Sciences, New Delhi 110029, India.
J Med Microbiol. 2017 Jul;66(7):999-1004. doi: 10.1099/jmm.0.000513. Epub 2017 Jul 13.
Resistant Gram-negative bacterial (GNB) infections, apart from tremendously escalating the cost of treatment, are a cause for substantial morbidity and mortality among hospitalized patients. Such bacteria are rapidly acquiring resistance to many antimicrobial agents, especially the beta-lactams which are the most frequently prescribed antimicrobials in hospital and community patient care settings, and now also to colistin; a last-line drug to treat infections with such bacteria. The greatest threat to antimicrobial treatment is the production of metallo beta-lactamases, and plasmid-mediated serine carbapenemases.
We conducted a two-year study to observe the pattern of beta-lactamase enzyme production (extended spectrum beta-lactamases (ESBLs), AmpC and carbapenemases) among the nosocomial GNB isolated from intensive care units (ICUs) of North and South Indian hospitals. A total of 761 non-duplicate GNB were included in the study from North (554; 73 %) and South India (207; 27 %). All strains were subjected to Clinical and Laboratory Standards Institute (CLSI) recommended screening tests for detection of beta-lactamase production, followed by polymerase chain reaction (PCR)-based detection of clinically important beta-lactamase genes mediating resistant phenotypes among these isolates.
Out of the 761 GNB, Acinetobacter spp., Klebsiella spp., Pseudomonas spp., Enterobacter spp. and others were 27, 23 , 21 , 17 , 5 and 7 % respectively. A high prevalence of ESBL was found across all genera in these strains. The carbapenem resistance was higher in North than in South Indian GNB. The level of AmpC production was comparatively lower in both North and South Indian strains.
Beta-lactamases showed tremendous variation in geographic distribution. Thus, their detection and characterization is important from a clinical-epidemiological, laboratory and infection control point of view. Knowledge of this epidemiology can predict the empiric antimicrobial treatment.
耐革兰氏阴性菌（GNB）感染不仅会大幅增加治疗成本，也是住院患者发病和死亡的重要原因。此类细菌正迅速对多种抗菌药物产生耐药性，尤其是β-内酰胺类药物，这类药物是医院和社区患者护理环境中最常使用的抗菌药物，现在对黏菌素也产生了耐药性；黏菌素是治疗此类细菌感染的最后一线药物。对抗菌治疗最大的威胁是金属β-内酰胺酶和质粒介导的丝氨酸碳青霉烯酶的产生。
我们进行了一项为期两年的研究，以观察从印度北部和南部医院重症监护病房（ICU）分离出的医院内GNB中β-内酰胺酶的产生模式（超广谱β-内酰胺酶（ESBLs）、AmpC和碳青霉烯酶）。该研究共纳入761株非重复GNB，其中来自印度北部的有554株（73%），来自印度南部的有207株（27%）。所有菌株均按照临床和实验室标准协会（CLSI）推荐的筛选试验检测β-内酰胺酶的产生，随后通过基于聚合酶链反应（PCR）的方法检测这些分离株中介导耐药表型的临床重要β-内酰胺酶基因。
在761株GNB中，不动杆菌属、克雷伯菌属、假单胞菌属肠杆菌属及其他菌属分别占27%、23%、21%、17%、5%和7%。在这些菌株的所有菌属中均发现ESBL的高流行率。印度北部GNB对碳青霉烯类药物的耐药性高于南部。印度北部和南部菌株的AmpC产生水平相对较低。
β-内酰胺酶在地理分布上表现出巨大差异。因此，从临床流行病学、实验室和感染控制的角度来看，对其进行检测和鉴定非常重要。了解这种流行病学情况有助于预测经验性抗菌治疗。
