Data on the occurrence of antimicrobial resistance in human infections from Salmonella and Campylobacter in Europe has revealed little progress.

The European Centre for Disease Prevention and Control (ECDC) and European Food Safety Authority (EFSA) found that resistance is still high in bacteria that are causing foodborne infections.

Data from 2018 and 2019 on antimicrobial resistance (AMR) in zoonotic and indicator bacteria from humans, animals and food are collected annually by EU member states and analyzed by EFSA and ECDC.

The 2018 monitoring focused on poultry and derived carcasses and meat, while in 2019 the target was pigs and calves under 1 year of age, and their meat.

Reporting of AMR included data on Salmonella, Campylobacter and indicator E. coli isolates, as well as from monitoring of presumptive ESBL‐/AmpC‐/carbapenemase‐producing E. coli isolates.

Salmonella and Campylobacter
In humans, high resistance to ciprofloxacin, an antibiotic commonly used to treat several types of infections, was reported for Salmonella Kentucky. In recent years, Salmonella Enteritidis resistant to nalidixic acid and/or ciprofloxacin has been increasingly reported in several countries.

The rising occurrence of fluoroquinolone and quinolone resistance in these Salmonella types probably reflects the spread of particularly resistant strains, said experts.

In Salmonella spp. from human cases in 2019, resistance to ampicillin, sulfonamides and tetracyclines was at overall high levels, while resistance to third-generation cephalosporins was low at 1.8 percent and 1.2 percent for cefotaxime and ceftazidime, respectively.

Only eight countries tested resistance to the last line antimicrobials azithromycin and tigecycline but resistance was low among Salmonella spp. at about 1 percent.

For Campylobacter, resistance to ciprofloxacin is so common in most countries that this antimicrobial is of limited use in treating such infections in humans.

The proportion of human Campylobacter jejuni isolates resistant to erythromycin was low at 1.5 percent but higher in Campylobacter coli at 12.9 percent.

High proportions of resistance to tetracycline were observed in Campylobacter jejuni and coli. Countries reported low resistance levels to gentamicin except Italy for Campylobacter coli.

Multiple resistance and trends over time
Combined resistance to two critically important antimicrobials — fluoroquinolones and third generation cephalosporines in Salmonella and fluoroquinolones and macrolides in Campylobacter — remains low. These antimicrobials are commonly used to treat serious infections from Salmonella and Campylobacter in humans.

Multidrug resistance (MDR) was high overall at 25.4 percent among Salmonella spp. from human cases. It was most frequently reported among monophasic Salmonella Typhimurium 1,4,[5],12:i:- and Salmonella Kentucky at about 73 percent. Eleven isolates were resistant to eight of the nine tested substances, only susceptible to meropenem.

MDR in isolates tested for four antimicrobial classes — fluoroquinolones, macrolides, tetracyclines and aminoglycosides — was overall low in Campylobacter jejuni but moderate in Campylobacter coli. The most common was resistance to both ciprofloxacin and tetracycline.

From 2015 to 2019, a decline in resistance to ampicillin and tetracyclines was seen in Salmonella isolates from humans in eight and eleven member states respectively. Increasing trends in resistance were more common than decreases for ciprofloxacin/quinolones and tetracycline in Salmonella Enteritidis and ampicillin in Salmonella Infantis.

Increasing trends of fluoroquinolone resistance were observed in Campylobacter jejuni in nine nations and for Campylobacter coli in two. Overall, tetracycline resistance went up but erythromycin resistance went down.

A decreasing trend has also been observed in the prevalence of extended-spectrum beta-lactamase (ESBL)- producing E. coli in samples from food producing animals from 13 nations between 2015 and 2019. This is important as particular strains of ESBL-producing E. coli are responsible for serious infections in humans, said experts.

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