Presence and distribution of extended-spectrum and AmpC beta-lactamases-producing Escherichia coli on poultry farms in Slovenia

The purpose of the study was to investigate the presence, distribution and dynamics of extended-spectrum beta-lactamases (ESBL) and plasmid-mediated AmpC beta-lactamases (AmpC) producing Escherichia coli (E. coli) in meat type poultry and their environment. Three broiler breeder flocks, four broiler flocks originating from these breeders, and four meat-type turkey flocks were included in a longitudinal study. A total of 349 samples were tested. All environmental samples collected before placement of birds on the farms were negative for ESBL-and AmpC-producing E. coli. However, during the observation period ESBL-producing E. coli were detected in 41 out of 186 samples (22.04%), while AmpC-producing isolates were identified in 10.75% of samples. Resistant strains belonged predominantly to E. coli phylogenetic group A(1) (36.2%), followed by group D-1 (24.1%), B1 (22.4%) and D-2 (10.3%). The only genes detected were bla(SHV-12), bla(CMY-2) and bla(CTX-M). No significant differences were seen in the rates of detection of resistant strains in feces (18.84%), air samples (31.42%) or organs of dead birds (20.73%), which suggested that air samples can be successfully used as an indicator for the identification of positive flocks in order to prevent or reduce cross contaminations in slaughter houses.