title: Multidrug resistance and transferability of blaCTX-M among extended-spectrum β-lactamase-producing enteric bacteria in biofilm.
abstract: This study aimed to investigate the occurrence of biofilm-forming extended-spectrum β-lactamase (ESBL)-producing enteric bacteria in hospital wastewater and to evaluate their antibiotic resistance behaviour and transferability of the plasmid-encoded blaCTX-M gene in biofilm. ESBL production was confirmed using the combined disc test and Etest. Amplification of blaCTX-M was performed by PCR. Antibiotic susceptibility was evaluated using the disc diffusion assay and broth dilution method. Transfer of blaCTX-M in planktonic and biofilm state was performed by broth mating and filter mating experiments, respectively. Among 110 enteric bacteria, 24 (21.8%) isolates belonging to Escherichia coli, Klebsiella pneumoniae and Enterobacter cloacae were found to produce ESBL and formed varying levels of biofilm in vitro. Presence of blaCTX-M was detected in 18 (75%) ESBL-producing isolates. A many fold increase in resistance to antibiotics was observed in biofilm. Among ESBL-producers, seven isolates could transfer the blaCTX-M gene by conjugation, with transfer frequencies ranging from 2.22×10(-4) to 7.14×10(-2) transconjugants/recipient cell in the planktonic state and from 3.04×10(-3) to 9.15×10(-1) in biofilm. The transfer frequency of blaCTX-M was significantly higher in biofilm compared with the planktonic state, and co-transfer of ciprofloxacin resistance was also detected in five isolates. This study demonstrates that biofilm-forming ESBL-producing enteric bacteria with a greater transfer frequency of resistance genes will lead to frequent dissemination of β-lactam and fluoroquinolone resistance genes in environmental settings. The emergence and spread of such multidrug resistance is a serious threat to animal and public health.
authors.affiliation: Department of Agricultural Microbiology, Aligarh Muslim University, Aligarh 202002, India.
authors.forename: Meenu
authors.initials: M
authors.lastname: Maheshwari
authors.affiliation: Department of Agricultural Microbiology, Aligarh Muslim University, Aligarh 202002, India. Electronic address: ahmadiqbal8@yahoo.co.in.
authors.forename: Iqbal
authors.initials: I
authors.lastname: Ahmad
authors.affiliation: Department of Biology, Faculty of Applied Sciences, Umm Al Qura University, Makkah, Saudi Arabia.
authors.forename: Abdullah Safar
authors.initials: AS
authors.lastname: Althubiani
mesh_terms: D018441:Biofilms; D024901:Drug Resistance, Multiple, Bacterial; D004755:Enterobacteriaceae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D006761:Hospitals; D062065:Wastewater / Q000382:microbiology; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D062065:Wastewater; D001618:beta-Lactamases
keywords: Antibiotic resistance; Biofilm; ESBL; Enteric bacteria; Extended-spectrum β-lactamase; bla(CTX-M)