6 Resistance in zoonotic bacteria

Read the full chapter about Resistance in zoonotic bacteria

 

Report Highlights 2023:

Resistance in zoonotic bacteria

As in previous years, resistance levels in Campylobacter jejuni isolated from humans were higher than in isolates from broilers and cattle, and among human isolates, resistance was higher in travel-associated cases compared to domestically acquired cases.

Compared to 2022, the percentage of fully sensitive C. jejuni increased in isolates from broilers (from 59% to 61%) and decreased in isolates from cattle (from 76% to 70%).

Erythromycin resistance remained rare in C. jejuni from humans (1%) and resistance was not observed in isolates from broilers or cattle.

Fluoroquinolone (ciprofloxacin) resistance remained common in C. jejuni isolates from human cases (54%) and broilers (34%) and increased by 7% in cattle (29%). Tetracycline resistance was common in C. jejuni from humans (30%) and broilers (27%), and less common in cattle (7%).

Resistance to ciprofloxacin and tetracycline in C. coli from pigs increased compared to the levels observed in 2021 (from 20% to 25% and 26% to 35%, respectively). Resistance to ertapenem was not observed in C. coli from pigs. C. coli isolates from humans exhibited generally more resistance than isolates from pigs, indicating that the human isolates likely originate from sources other than Danish pigs. Erythromycin resistance was seen in 11% of the tested human C. coli isolates.

A total of 697 human clinical Salmonella spp. isolates representing 88 different serotypes were tested. Most Salmonella spp. isolates from humans were fully sensitive (64%), while lower levels of full susceptibility were found in pigs (46%) and pork (25%).

Macrolide (azithromycin) resistance in Salmonella spp. remained low in isolates from human travel-associated (3%) and domestic cases (1%). No azithromycin resistance was reported in isolates
from domestic pork and a single S. Typhimurium resistant isolate was recovered from pigs.

Resistance to ciprofloxacin in Salmonella spp. was observed in 15% of the isolates from humans. Ciprofloxacin resistance in S. Typhimurium and monophasic S. Typhimurium increased in 2023 (from 3% to 12% and 8% to 11%, respectively). Fluoroquinolone resistance has not been recorded in S. Typhimurium from Danish pork since 2007 however, a single monophasic S. Typhimurium isolate from pigs was resistant to ciprofloxacin in 2023.

Resistance to 3rd generation cephalosporins, cefotaxime and ceftazidime, in Salmonella spp. is rare in human isolates (2%), and no resistance was found in isolates from pigs and domestic pork. No carbapenem resistance (meropenem) was observed in Salmonella spp. from humans, pigs and domestic pork.

After a three-year decreasing trend, multidrug resistance (MDR) in S. Typhimurium and its monophasic variant from domestic pork increased in 2023 by 27%, with an increase in the ratio between the prevalence of other MDR profiles and the combined resistance to ampicillin, sulfamethoxazole and tetracycline (ASuT).