Antimicrobial Resistance Gene Detection and Plasmid Typing Among Multidrug Resistant Enterococci Isolated from...

Area of Science:

• Environmental microbiology
• Molecular biology
• Public health

Background:

• Enterococci are opportunistic pathogens, and their multidrug resistance (MDR) is a growing public health concern.
• Environmental reservoirs, such as surface water, can harbor and disseminate antimicrobial resistance (AR) genes.
• Understanding the AR mechanisms and plasmid diversity in environmental enterococci is crucial for assessing potential risks.

Purpose of the Study:

• To determine the mechanisms of antimicrobial resistance (AR) and the abundance and diversity of plasmids in multidrug-resistant (MDR) enterococci from surface water.
• To identify specific AR genes and plasmid replicon families present in these environmental isolates.
• To compare AR gene profiles and plasmid types with those found in human and animal-associated enterococci.

Main Methods:

• Screening of 51 enterococci isolates for 27 AR genes conferring resistance to common antibiotics.
• Utilizing a plasmid classification system based on replication genes to identify Gram-positive plasmid replicon families.
• Molecular detection of specific AR genes, including erm(B), erm(C), aph(3')-IIIa, ant(6)-Ia, lnu(B), vat(E), qnr, and various tet genes.

Main Results:

• Twelve AR genes conferring resistance to erythromycin, tylosin, kanamycin, streptomycin, lincomycin, Q/D, ciprofloxacin, and tetracycline were identified.
• Twelve distinct plasmid replicon families (rep-families) were detected in two-thirds of the isolates.
• While common AR genes were found, many isolates had undetermined resistance genes, suggesting novel AR mechanisms in environmental enterococci.

Conclusions:

• Environmental enterococci possess diverse AR mechanisms and plasmid types, some distinct from those found in clinical or animal settings.
• Surface water acts as a reservoir for AR genes and plasmids, contributing to the broader landscape of antimicrobial resistance.
• Further research is needed to fully elucidate the AR mechanisms present in environmental enterococci and their potential for dissemination.