Molecular characterization and prevalence of ß-lactamase-producing Enterobacterales in livestock and poultry slaughterhouses wastewater in Iran.

Beta-lactamase-producing Enterobacterales bacteria cause severe hard-to-treat infections. Currently, they are spreading beyond hospitals and becoming a serious global health concern. This study investigated the prevalence and molecular characterization of extended-spectrum ß-lactamase and AmpC-type ß-lactamase-producing Enterobacterales (ESBL-PE, AmpC-PE) in wastewater from livestock and poultry slaughterhouses in Ardabil, Iran. A total of 80 Enterobacterales bacteria belonging to 9 species were identified. Among the isolates, Escherichia coli (n = 21/80; 26.2%) and Citrobacter spp. (n = 18/80; 22.5%) exhibited the highest frequency. Overall, 18.7% (n = 15/80) and 2.5% (n = 2/80) of Enterobacterales were found to be ESBL and AmpC producers, respectively. The most common ESBL producer isolates were E. coli (n = 9/21; 42.8%) and Klebsiella pneumoniae (n = 6/7; 85.7%). All AmpC-PE isolates belonged to E. coli strains (n = 2/21; 9.5%). In this study, 80% of ESBL-PE and 100% of AmpC-PE isolates were recovered from poultry slaughterhouse wastewater. All ESBL-PE and AmpC-PE isolates were multidrug-resistant. In total, 93.3% of ESBL-PE isolates harbored the blaCTX-M gene, with the blaCTX-M-15 being the most common subgroup. The emergence of ESBL-PE and AmpC-PE in wastewater of food-producing animals allows for zoonotic transmission to humans through contaminated food products and contaminations of the environment.

Characterization of beta-lactamase producing Enterobacterales isolated from an urban community wastewater treatment plant in Iran.

Background and Objectives: he occurrence and characteristics of Extended Spectrum- and AmpC-ß-lactamase producing Enterobacterales (ESBL-PE and AmpC-PE) in an urban wastewater treatment plant (WWTP) were investigated. Materials and Methods: A total of 30 wastewater samples were collected from all sections of WWTP. Enterobacterales were isolated and identified using standard microbiological tests. The antibiotic resistance profile was determined by the Kirby-Bauer disk diffusion method. Phenotypic screening for ESBL-PE and AmpC-PE isolates was performed by double-disk synergy and boronic acid disk potentiation tests, respectively. The isolates were examined for AmpC- and ESBL-encoding genes by PCR and sequencing methods. Results: Among 146 Enterobacterales isolates, 8.9% (n=13) [ESBL-only; 5.48% (n=8) and ESBL + AmpC; 3.42% (n=5)] were ESBL-producers and 15.75% (n=23) [AmpC-only; 12.33% (n=18) and ESBL + AmpC; 3.42% (n=5)] AmpC-producers. Hafnia spp. with 33.33% (n=1/3) and E. coli with 20.58% (n=7/34) [ESBL-only; 17.64% (n=6/34) and ESBL + AmpC; 2.94% (n=1/34)] were the most common ESBL-producing bacteria. Enterobacter spp. with 37.50% (n=6/16) of isolates were the most common AmpC-producing organisms. ESBL- and/or AmpC-producing isolates were identified in all parts of the WWTP including 80% (n=8/10) of samples taken from effluent. Among ESBL-producing isolates, bla CTX-M , bla TEM, and bla SHV ESBL-encoding genes were found in 61.5% (n=8), 15.3% (n=2), and 7.7% (n=1) of isolates, respectively. All CTX-M-type enzymes belonged to the CTX-M-1 group and CTX-M-15 subgroup. bla TEM and bla SHV type genes belonged to bla TEM-20 and bla HSV-12 subtypes, respectively. bla DHA with 73.9% (n=17/23), and bla CIT and bla FOX with 30.4% (n=7/23) each, were the most common AmpC-encoding genes among AmpC-producing isolates. Overall, 75% of ESBL-producing and 55.5% of AmpC-producing isolates exhibited multi-drug resistance phenotypes. The organisms were most resistant against ampicillin (82.2%) nalidixic acid (43.8%) and cephalexin (41.1%). Conclusion: ESBL- and AmpC-producing Enterobacterales spp. with diverse genetic resistance backgrounds in WWTP effluent poses a significant risk to public health.