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. 2023 May 29;12(6):981.
doi: 10.3390/antibiotics12060981.

Antibiotic Susceptibility Patterns and Virulence-Associated Factors of Vancomycin-Resistant Enterococcal Isolates from Tertiary Care Hospitals

Arockia Doss Susai Backiam  1 , Senbagam Duraisamy  2 , Palaniyandi Karuppaiya  2 , Senthilkumar Balakrishnan  3 , Balaji Chandrasekaran  4 , Anbarasu Kumarasamy  2 , Amutha Raju  5
Affiliations

Antibiotic Susceptibility Patterns and Virulence-Associated Factors of Vancomycin-Resistant Enterococcal Isolates from Tertiary Care Hospitals

Arockia Doss Susai Backiam et al. Antibiotics (Basel). .

Abstract

This study explored the prevalence of multi-drug resistance and virulence factors of enterococcal isolates obtained from various clinical specimens (n = 1575) including urine, blood, pus, tissue, catheter, vaginal wash, semen, and endotracheal secretions. Out of 862 enterococcal isolates, 388 (45%), 246 (29%), 120 (14%), and 108 (13%) were identified as Enterococcus faecalis, Enterococcus faecium, Enterococcus durans, and Enterococcus hirae, respectively, using standard morphological and biochemical methods. The antibiotic resistance profile of all these enterococcal isolates was checked using the disc diffusion technique. High-level resistance was observed for benzylpenicillin (70%) and vancomycin (43%) among E. faecalis and E. faecium isolates, respectively. This study also revealed the prevalence of 'multi-drug resistance (resistant to 3 antibiotic groups)' among the vancomycin-resistant enterococcal strains, and this was about 11% (n = 91). The virulence determinants associated with vancomycin resistance (VR) were determined phenotypically and genotypically. About 70 and 39% of E. faecalis and E. faecium isolates showed to be positive for all four virulence factors (gelatinase, protease, hemolysin, and biofilm). Among the several virulence genes, gelE was the most common virulence gene with a prevalence rate of 76 and 69% among E. faecalis and E. faecium isolates, respectively. More than 50% of VRE isolates harbored other virulence genes, such esp, asa, ace, and cylA. Similarly, the majority of the VR enterococcal isolates (n = 88/91) harbored vanA gene and none of them harbored vanB gene. These results disclose the importance of VR E. faecalis and E. faecium and the associated virulence factors involved in the persistence of infections in clinical settings.

Keywords: antibiotic resistance; biofilm; gelatinase; hemolysis; multi-drug resistance; protease; vancomycin-resistant enterococcus; virulence factors.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Antibiotic susceptibility/resistance profile of the enterococcal isolates from various clinical specimens determined assessed by antibiotic disk diffusion test (ADT).
Figure 2
Figure 2
The bar plot showing the percentage of positive phenotypic and genotypic virulence factors of vancomycin-resistant enterococcal isolates.
Figure 3
Figure 3
Pie chart revealing the different strength of the biofilm-producing ability of vancomycin-resistant enterococcal isolates (a) E. faecalis (n = 37), (b) E. faecium (n = 54). S: strong, M: moderate, W: weak, N: negative.
See this image and copyright information in PMC

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