[Occurrence of gentamicin-resistant coliforms in river water samples]

Area of Science:

• Environmental microbiology
• Bacterial genetics
• Antimicrobial resistance

Background:

• Coliform bacteria are indicators of water quality.
• Antimicrobial resistance is a growing public health concern.
• Gentamicin resistance in environmental bacteria can pose risks.

Purpose of the Study:

• To investigate the prevalence and characteristics of gentamicin-resistant coliforms in river water.
• To identify the bacterial species harboring gentamicin resistance.
• To determine the genetic basis of gentamicin resistance, specifically plasmid involvement.

Main Methods:

• Analysis of river water samples for total coliforms.
• Identification and characterization of gentamicin-resistant coliform isolates.
• Plasmid isolation and molecular analysis (e.g., size determination).
• Bacterial conjugation experiments to assess resistance transfer.

Main Results:

• 0.006% to 0.3% of total coliforms in river water samples exhibited gentamicin resistance.
• Klebsiella species (86.5%) were the predominant gentamicin-resistant coliforms identified.
• A common gentamicin resistance (Gm) plasmid of approximately 150 Md was frequently isolated from Klebsiella oxytoca, K. pneumoniae, and E. coli.
• All gentamicin-resistant wild strains successfully transferred resistance to E. coli K-12.
• Klebsiella strains often harbored multiple plasmids, including R-plasmids.

Conclusions:

• River water serves as a reservoir for gentamicin-resistant coliforms, particularly Klebsiella.
• The 150 Md Gm-plasmid is a significant factor in gentamicin resistance among these environmental bacteria.
• The ability of these strains to transfer resistance highlights the potential for wider dissemination of gentamicin resistance genes in aquatic environments.