Download PDF
CC BY-NC-ND 4.0 · J Lab Physicians 2022; 14(03): 290-294
DOI: 10.1055/s-0042-1742423
Original Article

Molecular Characterization of High-Level Aminoglycoside Resistance among Enterococcus Species

Harish Manoharan 
1   Department of Microbiology, Sri Ramachandra Institute for Higher Education and Research, Chennai, Tamil Nadu, India
,
Aishwarya K.V. Lalitha
1   Department of Microbiology, Sri Ramachandra Institute for Higher Education and Research, Chennai, Tamil Nadu, India
,
Shanthi Mariappan
1   Department of Microbiology, Sri Ramachandra Institute for Higher Education and Research, Chennai, Tamil Nadu, India
,
Uma Sekar
1   Department of Microbiology, Sri Ramachandra Institute for Higher Education and Research, Chennai, Tamil Nadu, India
,
Geetha P. Venkataramana
1   Department of Microbiology, Sri Ramachandra Institute for Higher Education and Research, Chennai, Tamil Nadu, India
› Author Affiliations
› Further Information
Also available at
   Permissions and Reprints

Abstract

Background Enterococci are nosocomial pathogen. They can develop high-level resistance to aminoglycoside by producing aminoglycoside modifying enzymes (AMEs). In enterococci, high level resistance to aminoglycosides is mediated by acquisition of plasmid mediated genes encoding for aminoglycoside modifying enzymes (AMEs). High level gentamicin resistance (MIC ≥ 500μg /mL) is predominantly mediated by aac(6′)-Ie-aph(2″)-Ia, encoding the bifunctional aminoglycoside modifying enzyme AAC(6′)-APH(2″). This enzyme eliminates the synergistic activity of gentamicin when combined with a cell wall active agent. Other AME genes such as aph(2″)-Ib, aph(2″)-Ic, aph(2″)-Id and ant(4′)-1a have also been detected in enterococci.

Objective This study was carried out to determine the diverse prevalence of AME and their pattern of occurrence in the clinical isolates of Enterococci.

Materials and Methods A total number of 150 clinical isolates were included in this study. Susceptibility to various antibiotics was determined by disc diffusion. Minimum Inhibitory Concentration (MIC) was ascertained by agar dilution method. Polymerase chain reaction was done to screen the following AMEs (aac(6′)-Ie-aph(2″)-Ia; aph(2″)-Ib; aph(2″)-Ic; aph(2″)-Id and aph(3′)- IIIa genes).

Results 51.3% of the study isolates exhibited high level gentamicin resistance. Polymerase chain reaction revealed that aph(3′)-111a is the most prevalent AME, followed by aac(6′)-1e-aph(2″)-1a. The combination of both the genes were detected in 44.1% of the study isolates. The rest of the AMEs and their combinations were not encountered in this study. 8.6% of the study isolates did not harbour any AME genes screened for, but was phenotypically resistant to gentamicin. In contrast 31.3% anchored the AME genes but phenotypically appeared susceptible to gentamicin.

Conclusion This study indicates the high- level aminoglycoside resistance disseminated among Enterococci in our geographical region. It also emphasizes the detection of AMEs by PCR is mandatory because strains that appear susceptible by disc diffusion and/or MIC method may harbour one or more AMEs genes leading to therapeutic failure.

Keywords

AMEs - Enterococcus species - high-level aminoglycoside resistance - encoding genes


Publication History

Article published online:
23 February 2022

© 2022. The Indian Association of Laboratory Physicians. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)

Thieme Medical and Scientific Publishers Pvt. Ltd.
A-12, 2nd Floor, Sector 2, Noida-201301 UP, India

 

  • Reference

  • 1 García-Solache M, Rice LB. The Enterococcus: a model of adaptability to its environment. Clin Microbiol Rev 2019; 32 (02) e00058-18
    CrossrefPubMedGoogle Scholar
  • 2 Padmasini E, Padmaraj R, Ramesh SS. High level aminoglycoside resistance and distribution of aminoglycoside resistant genes among clinical isolates of Enterococcus species in Chennai, India. ScientificWorldJournal 2014; 2014: 329157
    CrossrefPubMedGoogle Scholar
  • 3 Kobayashi N, Alam M, Nishimoto Y, Urasawa S, Uehara N, Watanabe N. Distribution of aminoglycoside resistance genes in recent clinical isolates of Enterococcus faecalis, Enterococcus faecium and Enterococcus avium. Epidemiol Infect 2001; 126 (02) 197-204
    CrossrefPubMedGoogle Scholar
  • 4 Vakulenko SB, Donabedian SM, Voskresenskiy AM, Zervos MJ, Lerner SA, Chow JW. Multiplex PCR for detection of aminoglycoside resistance genes in enterococci. Antimicrob Agents Chemother 2003; 47 (04) 1423-1426
    CrossrefPubMedGoogle Scholar
  • 5 Ozarslan Kurtgoz S, Ozer B, Inci M, Duran N, Yula E. Vancomycin and high-level aminoglycoside resistance in Enterococcus species. Microbiol Res (Pavia) 2016; 7: 1
    CrossrefGoogle Scholar
  • 6 Carlier C, Courvalin P. Emergence of 4′,4"-aminoglycoside nucleotidyltransferase in enterococci. Antimicrob Agents Chemother 1990; 34 (08) 1565-1569
    CrossrefPubMedGoogle Scholar
  • 7 Gray GS, Fitch WM. Evolution of antibiotic resistance genes: the DNA sequence of a kanamycin resistance gene from Staphylococcus aureus. Mol Biol Evol 1983; 1 (01) 57-66
    PubMedGoogle Scholar
  • 8 Matsumura M, Katakura Y, Imanaka T, Aiba S. Enzymatic and nucleotide sequence studies of a kanamycin-inactivating enzyme encoded by a plasmid from thermophilic bacilli in comparison with that encoded by plasmid pUB110. J Bacteriol 1984; 160 (01) 413-420
    CrossrefPubMedGoogle Scholar
  • 9 Trieu-Cuot P, Courvalin P. Nucleotide sequence of the Streptococcus faecalis plasmid gene encoding the 3′5"-aminoglycoside phosphotransferase type III. Gene 1983; 23 (03) 331-341
    CrossrefPubMedGoogle Scholar
  • 10 Shete V, Grover N, Kumar M. Analysis of aminoglycoside modifying enzyme genes responsible for high-level aminoglycoside resistance among enterococcal isolates. J Pathogens 2017; 2017: 3256952
    CrossrefPubMedGoogle Scholar
  • 11 Diab M, Salem D, El-Shenawy A. et al. Detection of high level aminoglycoside resistance genes among clinical isolates of Enterococcus species. Egypt J Med Hum Genet 2019; 20: 28
    CrossrefGoogle Scholar
  • 12 Moussa AA, Md Nordin AF, Hamat RA, Jasni AS. High level aminoglycoside resistance and distribution of the resistance genes in Enterococcus faecalis and Enterococcus faecium from teaching hospital in Malaysia. Infect Drug Resist 2019; 12: 3269-3274
    CrossrefPubMedGoogle Scholar