The latest data on antimicrobial resistance (AMR) of bacteria from humans, animals, and food shows there is still plenty of room for improvement in Europe.

The European Centre for Disease Prevention and Control (ECDC) and European Food Safety Authority (EFSA) said resistance of Salmonella and Campylobacter to commonly used antimicrobials is frequent in humans.

“Antimicrobial resistance is one of the greatest threats we face worldwide, affecting humans, animals, and the environment. In our work, we embody the One Health approach, recognizing the close links and interdependency of the health of humans, animals, plants, and the wider environment,” said ECDC and EFSA chief scientists Mike Catchpole and Carlos Das Neves.

Antimicrobial resistance data on bacteria from humans, animals, and food are collected annually by 27 EU countries. Northern Ireland, Albania, Iceland, Norway, Switzerland, and North Macedonia also shared data. The report has the main findings of 2020 to 2021 AMR monitoring in Salmonella, Campylobacter jejuni, and Campylobacter coli in humans and food-producing animals.

In 2020, it was mandatory to report AMR data from poultry flocks and derived meat, while in 2021, the focus was on fattening pigs and calves and their meat.

In Salmonella from human cases in 2021, resistance to ampicillin, sulfonamides, and tetracyclines was at high levels, while resistance to third-generation cephalosporins was low for both cefotaxime and ceftazidime. A moderate level of resistance to ciprofloxacin was observed in human cases; however, an extremely high proportion of resistant isolates was noted in Salmonella Kentucky.

Combined resistance to ciprofloxacin and cefotaxime, classed as high priority critically important antimicrobials, was very low in Salmonella isolates from humans.

Multidrug resistance (MDR) was high for Salmonella in human cases, ranging from low in Salmonella Enteritidis to very high among Salmonella Kentucky and extremely high for monophasic Salmonella Typhimurium. MDR is resistant to three or more antimicrobial classes.

Campylobacter findings
Data showed high levels of resistance to fluoroquinolones, which are critically important antimicrobials used to treat Campylobacter infections in humans.

High to extremely high resistance levels to ciprofloxacin were also observed in human Campylobacter jejuni and coli isolates. The level of resistance is now so high, it is no longer recommended in the treatment of severe infections in humans.

Macrolides, including erythromycin, are the main class of antibiotics used as the first-line treatment of campylobacteriosis. Resistance to erythromycin, another critically important antimicrobial, was at low levels in Campylobacter jejuni from humans. However, higher levels were observed in Campylobacter coli isolates from people. The level of resistance to tetracycline was high in Campylobacter jejuni and extremely high in Campylobacter coli from humans.

Combined resistance to ciprofloxacin and erythromycin was lower in Campylobacter jejuni isolates than in Campylobacter coli isolates for humans.

Portugal had the highest prevalence of resistance to erythromycin in Campylobacter coli from fattening pigs in 2021 and the top level of resistance in humans, suggesting that pigs could be a reservoir of erythromycin-resistant Campylobacter coli. This is of public health concern because macrolides, such as erythromycin and azithromycin, have become the first-line treatment of human campylobacteriosis, said EFSA and ECDC.

A higher-than-expected level of resistance to ertapenem was found in Campylobacter coli isolated from calves in 2021. This is also worrying for public health as carbapenems, alongside aminoglycocides, are the antimicrobial classes recommended for treating invasive Campylobacter infections in people.

Data revealed the prevalence of Extended-spectrum Beta-lactamases and AmpC beta-lactamases producing E. coli is decreasing. Resistance of E. coli to carbapenem remains rare in food-producing animals and humans. Carbapenem is a class of last-resort antimicrobials.

Another key finding from the 2021 monitoring was the detection of rifampicin resistance in isolates from dairy cows and bovine meat. Vancomycin and rifampicin are important compounds in human medicine for the treatment of methicillin-resistant Staphylococcus aureus (MRSA).