Isolation and bio-control of Extended Spectrum Beta-Lactamase (ESBL)-producing Escherichia coli contamination in raw chicken meat by using lytic bacteriophages

Abstract

Extended Spectrum Beta-Lactamase-producing Escherichia coli (ESBLEC) were isolated from 12/13 (92.3%) raw chicken meat samples by using selective culture and PCR. Of the 27 ESBLEC analyzed, 33.3% (9/27) of isolates were positive for ESBL of CTX-M group 1 followed by TEM (22.2%), SHV (22.2%), CTX-M group 2 (11.1%), and CTX-M group 9 (11.1%). None of ESBLEC tested were positive for stx1, stx2, eae, ehxA, saa, and subAB genes of Shiga toxin-producing E. coli. Among 22 isolated phages, phages PBL66-CL1 and PBL116-CS6 infected 21 (77.7%) and 20 (74%) of 27 ESBLEC isolates examined, respectively. The remaining phages lysed less than 50% of the hosts tested. Compared to non-treatment, the treatment of isolate EBL116 in the broth medium with phage cocktail of PBL66-CL1 and PBL116-CS6 at 25 °C and 5 °C after 6 h significantly reduced bacterial viable counts by 5.06 and 1.33 log CFU/mL, respectively. When the treatment was performed on raw chicken meat samples, viable counts of EBL116 were also decreased by 2.02 and 1.67 log CFU/4 cm2 meat piece after 6 h at 25 °C and 5 °C, respectively. This study demonstrates a high prevalence of ESBLEC in raw chicken meat and possible use of lytic phages as bactericide for controlling ESBLEC.