Acquired genetic mechanisms of a multiresistant bacterium isolated from a treatment plant receiving wastewater from antibiotic production

Appl Environ Microbiol. 2013 Dec;79(23):7256-63. doi: 10.1128/AEM.02141-13. Epub 2013 Sep 13.

Abstract

The external environment, particularly wastewater treatment plants (WWTPs), where environmental bacteria meet human commensals and pathogens in large numbers, has been highlighted as a potential breeding ground for antibiotic resistance. We have isolated the extensively drug-resistant Ochrobactrum intermedium CCUG 57381 from an Indian WWTP receiving industrial wastewater from pharmaceutical production contaminated with high levels of quinolones. Antibiotic susceptibility testing against 47 antibiotics showed that the strain was 4 to >500 times more resistant to sulfonamides, quinolones, tetracyclines, macrolides, and the aminoglycoside streptomycin than the type strain O. intermedium LMG 3301T. Whole-genome sequencing identified mutations in the Indian strain causing amino acid substitutions in the target enzymes of quinolones. We also characterized three acquired regions containing resistance genes to sulfonamides (sul1), tetracyclines [tet(G) and tetR], and chloramphenicol/florfenicol (floR). Furthermore, the Indian strain harbored acquired mechanisms for horizontal gene transfer, including a type I mating pair-forming system (MPFI), a MOBP relaxase, and insertion sequence transposons. Our results highlight that WWTPs serving antibiotic manufacturing may provide nearly ideal conditions for the recruitment of resistance genes into human commensal and pathogenic bacteria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • DNA Mutational Analysis
  • DNA Transposable Elements
  • Drug Resistance, Bacterial*
  • Gene Transfer, Horizontal
  • Genome, Bacterial
  • India
  • Industrial Waste*
  • Microbial Sensitivity Tests
  • Mutation, Missense
  • Ochrobactrum / drug effects*
  • Ochrobactrum / genetics*
  • Ochrobactrum / isolation & purification
  • Sequence Analysis, DNA
  • Wastewater / microbiology*

Substances

  • Anti-Bacterial Agents
  • DNA Transposable Elements
  • Industrial Waste
  • Waste Water