7 Resistance in indicator bacteria

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Report Highlights 2024:
Resistance in indicator bacteria

Over the last 5-year monitoring period, there have been no statistically significant trends in the occurrence of fully-susceptible indicator E. coli from broilers, pigs or cattle. Notably, in 2024 compared to 2023, full-susceptibility occurrence increased by 11% in isolates from cattle and decreased by 8% in isolates from pigs.

The occurrence of multidrug-resistant indicator E. coli compared to the previous year remained relatively constant in broilers and pigs and visibly decreased in cattle, in a clear shift from the increasing trend observed in recent years. Combined resistance to ampicillin, sulfamethoxazole, and tetracycline (ASuT) continued to be the most common multidrug-resistance profile among E. coli from pigs, however the relative occurrence of other profiles increased in 2024.

Compared to 2023, the occurrence of resistance to most antimicrobials in the test panel suffered a decrease in isolates from broilers and cattle, and an increase in isolates from pigs. The fluctuations between the two years were minor among isolates from broilers and pigs (1-5%), and more pronounced for cattle isolates (5-12%). Among pig isolates (although by a limited magnitude), there was an increase in occurrence of resistance to aminoglycosides (amikacin and gentamicin) and macrolides (azithromycin).

As in previous years, no colistin, meropenem or tigecycline resistance were detected in indicator E. coli. Resistance to amikacin, gentamicin, third generation cephalosporins and azithromycin were either absent or detected at low levels. Resistance to ciprofloxacin continued to be low in isolates from cattle and pigs and continued decreasing in broiler isolates.

As in previous years, samples from broilers, broiler meat and turkey meat examined for carbapenemase-producing (CP) E. coli (including OXA-48) were found negative. The occurrence of ESBL- or AmpC- producing E. coli remained constant below 5% in samples from broilers and domestic broiler meat, while it increased in samples from imported broiler meat and decreased in samples from imported turkey meat, by approximately 20%, compared to 2022.