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Category: Volume 09 Issue 01 January 2021
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Title: Phenotypic Characterization and Antimicrobial Susceptibility Pattern of Enterococcal Isolates from Clinical Samples with Special Reference to Vancomycin Minimum Inhibitory Concentration (MIC)

Authors: Saba Shama, Anuradha De, Jayanthi Shastri

 DOI: https://dx.doi.org/10.18535/jmscr/v9i1.43

Abstract

Introduction: Enterococcal infections pose therapeutic challenges because of its intrinsic and acquired resistance to vancomycin as well as the ability to produce high level gentamicin resistance (HLGR) and β-lactamases.

Objectives: A study was undertaken to characterize different strains of enterococci from clinical specimens and to study their antimicrobial susceptibility pattern, including Minimum Inhibitory Concentration (MIC) to vancomycin, high-level aminoglycoside resistance (HLAR) and β-lactamase production.

Material and Methods: Single enterococcal isolates recovered from clinical specimens received for bacterial culture in this hospital during January 2016 to June 2017 were included in the study. Enterococci were identified and speciated by standard biochemical tests. The isolated enterococci were then tested for antimicrobial susceptibility by Kirby Bauer Disc Diffusion Method (KBDDM), as per CLSI guidelines. Susceptibility to vancomycin was also performed by Minimum Inhibitory Concentration (MIC) using E-strip method. HLAR was detected by using gentamicin disc 120 µg and β-lactamase production by nitrocefin disc.

Results: Total 100 enterococci were isolated during this period, out of which 90 were Enterococcus faecalis, 8 E. faecium and 2 E. solitarius. Most of the samples were from pus and wound swabs (49%). Maximum isolation was from Medicine ward (25%), followed by Surgery ward (14%). Among ICUs, maximum isolation was from MICU (13%). Antibiotic susceptibility pattern of enterococcal isolates showed Vancomycin resistance in 3% isolates by KBDDM and in 4% isolates by MIC. Maximum resistance was shown against erythromycin (64.7%). High level gentamycin resistance (HLGR) was seen in 48% isolates and 13% isolates were β-lactamase producers.

Conclusion: This study highlighted the problem of multi-drug resistant enterococci, especially with reference to VRE and HLAR. Therefore, an effective infection control policy is required to control the spread of enterococci, with increasing awareness amongst microbiologists & clinicians.

Keywords: Enterococcus species; ABS pattern; Vancomycin MIC.

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Corresponding Author

Saba Shama

Department of Microbiology, T. N. Medical College & B.Y.L Nair Charitable Hospital, Mumbai, India