Tuhina Banerjee, Anupurba Shampa, Karuna Tiwari
Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India.
Indian J Pathol Microbiol. 2016 Jan-Mar;59(1):50-5. doi: 10.4103/0377-4929.174795.
Several enterococcal species are increasingly being reported from clinical infections, besides the major species.
This study was undertaken to determine the prevalence of unusual enterococcal species and their antimicrobial susceptibility patterns, virulence factors, and molecular characterization.
The study was conducted in Department of Microbiology and associated Tertiary Care University Hospital in North India.
Enterococcal isolates were collected for a period of 2 years from clinical specimens. Identification and elaborate phenotypic characterization was done biochemically. All the isolates were tested by Kirby-Bauer disc diffusion method and breakpoint minimum inhibitory concentration for susceptibility against standard antibiotics. Screening for vancomycin-resistant enterococci (VRE), high-level aminoglycoside resistance was done on brain heart infusion agar incorporated with 6 μg/ml vancomycin, 500 μg/ml gentamicin, and 2000 μg/ml streptomycin, respectively. VRE isolates were tested for the presence of vanA, vanB, and vanC genes and high-level gentamicin resistant (HLGR) isolates for aac-6'- aph-2' gene by polymerase chain reaction (PCR). Hemolysin and gelatinase production, hemagglutination and biofilm formation were detected along with asa1, gelE, esp, hyl, and cylA genes by multiplex PCR.
Of 403 enterococci, 93 (23.07%) isolates were identified as unusual species and atypical variants. Resistance of 52.68%, 46.23%, 44.08%, and 6.45% for ampicillin, ciprofloxacin, high strength gentamicin, and vancomycin, respectively were noted. Presence of vanC gene in Enterococcus gallinarum and Enterococcus casseliflavus isolates and vanA gene in Enterococcus durans and Enterococcus hirae and aac-6'- aph-2'' gene was found in 33.14% (14/41) of the HLGR isolates. The most frequent virulence factor was biofilm production. Only a few isolates harbored asa1 (2), gelE (9), and hyl (3) genes.
Considerable prevalence of pathogenic unusual species of enterococci was seen along with their emerging drug resistance and virulence. Complete identification and routine speciation is essential to limit their emergence as major species in near future.
除了主要的肠球菌种类外，临床感染中越来越多地报告了几种其他肠球菌种类。
本研究旨在确定不常见肠球菌种类的流行情况及其抗菌药物敏感性模式、毒力因子和分子特征。
该研究在印度北部的微生物学系及相关的三级护理大学医院进行。
从临床标本中收集肠球菌分离株，为期2年。通过生化方法进行鉴定和详细的表型特征分析。所有分离株均采用 Kirby-Bauer 纸片扩散法进行检测，并采用断点最低抑菌浓度法检测对标准抗生素的敏感性。分别在含有6μg/ml万古霉素、500μg/ml庆大霉素和2000μg/ml链霉素的脑心浸液琼脂上筛选耐万古霉素肠球菌（VRE）、高水平氨基糖苷类耐药性。通过聚合酶链反应（PCR）检测VRE分离株中vanA、vanB和vanC基因的存在情况，以及高水平庆大霉素耐药（HLGR）分离株中aac-6'-aph-2'基因的存在情况。通过多重PCR检测溶血素和明胶酶的产生、血凝和生物膜形成情况以及asa1、gelE、esp、hyl和cylA基因。
在403株肠球菌中，93株（23.07%）分离株被鉴定为不常见种类和非典型变体。氨苄西林、环丙沙星、高强度庆大霉素和万古霉素的耐药率分别为52.68%、46.23%、44.08%和6.45%。在鹑鸡肠球菌和格氏肠球菌分离株中发现了vanC基因，在耐久肠球菌和平肠球菌分离株中发现了vanA基因，在33.14%（14/41）的HLGR分离株中发现了aac-6'-aph-2''基因。最常见的毒力因子是生物膜形成。只有少数分离株携带asa1（2株）、gelE（9株）和hyl（3株）基因。
观察到致病性不常见肠球菌种类相当普遍，同时出现了耐药性和毒力。进行完整的鉴定和常规分类对于在不久的将来限制它们成为主要种类至关重要。
