Highest priority critically important antimicrobials-resistant Escherichia coli and Salmonella spp. isolated from pig farms environments and pork meat from Argentina

NIEVAS H; GRIFFO D; ALARCÓN L; AURNAGUE C; CARRIQUIRIBORDE M; IZA R; MARTÍNEZ ZUGAZUA M; NIEVAS VF; ORUSSA N; AYALA C; BALLESTEROS C; LUZBEL DE LA SOTA R; MESTORINO N; REYHER K; WILLIAMS S; GALLI L; MOREDO FA

Parma

Conferencia; 9th International Conference on Emerging Zoonoses; 2024

Medically Important Antimicrobials (MIA) for human medicine need to be preserved by reducing their use in the non-human sectors. The WHO, in collaboration with the FAO, the UNEP and the WOAH, developed a MIA list as a joint effort to harmonize and align related guidance to the four organizations. Pig farm environments and pork meat can serve as reservoirs of AMR, which can be monitored using Escherichia coli as an indicator bacteria and Salmonella as a zoonotic pathogen. This study aimed to determine the presence of highest priority critically important antimicrobial (HPCIA)-resistant E. coli and Salmonella spp. from pig environments and pork meat in Argentina. Between March and May 2021, 102 samples belonging to 17 pig farm environments located in Buenos Aires, Entre Ríos, and Santa Fe provinces were processed. Six samples from each farm were collected: three from fecal contaminated areas with high densities of animal traffic and three pools of feces. Between June and December 2023, a total of 240 pork meat samples were collected from 38 butcheries in La Plata city, Buenos Aires. Briefly, 25 g of each sample was mixed with 225 mL of buffered peptone water followed by incubation overnight at 37 °C. Cefotaxime and fosfomycin were selected within the HPCIA to search resistant E. coli. Enriched cultures were inoculated on Mac Conkey agar plates supplemented with 4 mg/L of cefotaxime. To recover fosfomycin-resistant E. coli, enriched cultures were spread on EMB agar with a fosfomycin disk. One colony was picked per plate. Isolation of Salmonella spp. was performed according to ISO 6579-1:2017. To determine the resistance profile against the HPCIA cefotaxime (CTX), ciprofloxacin (CIP) and fosfomycin (FOS), agar diffusion method and agar spot for colistin was used. All pig farms were positive for at least two cefotaxime-resistant (CTX-R) E. coli. A total of 84 E. coli CTX-R, FOS-R or CTX/FOS-R were obtained from the pig farms, with the predominant resistance profiles being CTX/CIP (24), CTX (23), CTX/FOS and /o CIP (20) and FOS (5). Twenty-four butcheries were positive for at least one resistant E. coli (24/38). A total of 35 CTX-R or CTX/FOS-resistant E. coli strains were obtained, with the predominant resistance profile being CTX/CIP (9) and CTX (9). Thirteen E. coli showed resistance to FOS/CTX and/or CIP. Salmonella London was isolated from the pool of feces from one pig farm. S. Bredeney, S. Agona, S. London and Salmonella spp. were isolated from five butcheries. All Salmonella strains were susceptible to the HPCIA tested. Although no major differences were observed between the resistance profiles of E. coli isolated in farms respect to butcheries, the amount of resistant E. coli is five times higher on farms. These results indicate that in the same way that interventions are being made to promote food handling to reduce the risk of cross-contamination, good production practices should be promoted not only to reduce AMR but also potential colonization with resistant bacteria from farmers and veterinarians, posing both a health risk to themselves and to the community.