Emergence of antimicrobial resistance and virulence factors among the unusual species of enterococci, from North India.
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Date
2016-01
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Abstract
Background: Several enterococcal species are increasingly being reported from
clinical infections, besides the major species. Aim: This study was undertaken to
determine the prevalence of unusual enterococcal species and their antimicrobial
susceptibility patterns, virulence factors, and molecular characterization.
Study Design and Settings: The study was conducted in Department of
Microbiology and associated Tertiary Care University Hospital in North India.
Materials and Methods: 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.
Results: 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. Conclusion: 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.
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Keywords
Antimicrobial, emergence, enterococci, species, unusual
Citation
Banerjee Tuhina, Shampa Anupurba, Tiwari Karuna. Emergence of antimicrobial resistance and virulence factors among the unusual species of enterococci, from North India. Indian Journal of Pathology & Microbiology. 2016 Jan-Mar 59(1): 50-55.