Linezolid-resistant Enterococcus isolates in Menoufia University Hospitals and community-acquired infections: Genetic determinants and risk factors

Document Type : Original Article


1 Department of Medical Microbiology and Immunology, Faculty of Medicine, Menoufia University, Shebin al Kom, Egypt

2 Department of Medical Microbiology and Immunology, National Liver Institute, Menoufia University, Shebin al Kom, Egypt


Background: E. faecalis and E. faecium are significant culprits in both hospital (HAIs) and community-acquired infections (CAIs), displaying inherent and acquired resistance to diverse antibiotic classes. Linezolid serves as a last-resort antibiotic for enterococcal infections. This study aimed to detect the prevalence of enterococcal infections in hospital and community contexts, assess the antibiotic susceptibility of E. faecalis and E. faecium and identify the underlying linezolid resistance mechanisms. Methods: Vitek-2 Compact System identified and determined the antibiotic susceptibility patterns for E. faecalis and E. faecium isolates. Conventional PCR assay was utilized to explore the acquired linezolid resistance genes (PoxtA, OptrA, and Cfr). The identification of 23S rRNA mutations G2505A was accomplished through PCR-based sequencing. Results: Among hundred enterococcus isolates (56% E. faecalis & 44% E. faecium), genetic determinants of linezolid resistance were identified in 39 isolates. However, only 12 isolates were confirmed as being resistant to linezolid. Hospital-acquired infections had significantly more linezolid resistance determinants (79.5%) than those of community origin (20.5%). The most common resistance mechanisms among linezolid-resistant enterococci (LRE) were concurrent presence of OptrA and PoxtA (33.3%), 23SrRNA G2505A mutation (25%) and singular OptrA (25%) or PoxtA (8.3%). Notably, one hospital-acquired isolate (8.3%) showed 23S rRNA mutation alongside OptrA and PoxtA genes. Prior hospitalization, invasive devices, malignancy and immunosuppressives were risk factors for emergence of LRE. Conclusion: The distribution of Enterococcus species, antibiotic resistance and increasing linezolid resistance genes in hospital underscore the complexity of HAIs.

This emphasizes the urgent importance of research and targeted interventions for effective management.


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