Antibiotic resistance in gastrointestinal infections. Results of a large monitoring system

Background

Antibiotic resistance (AR) represents a growing public health threat. In Community of Madrid (CM), Spain, monitoring of AR for several foodborne diseases has been established since 2023.

Objectives

To describe AR in Campylobacter, Salmonella and Shigella human infections in CM between 2023 and 2025.

Methods

All campilobacteriosis, salmonellosis and shigellosis declared to the regional surveillance system from 01/01/2023 to 31/12/2025, with Antimicrobial Susceptibility Testing (AST) were included. Proportion of resistances for each antibiotic by microorganism and year, as well as that of multidrug-resistance (MDR) and global resistance (at least to one antibiotic, -GR-) were calculated.

Results

Of 17,068 campylobacteriosis registered, 71.6% had AST. Among them, 88,1% were resistant to ciprofloxacin, 70.5% to tetracyclines and 1.8% were MDR. GR was 76.8%, with no temporal trends. C. coli showed a higher proportion of MDR strains (6.1%). Among the 4,469 salmonellosis, 70.5% had AST. There was a high proportion of resistances to ampicillin (29.8%), ciprofloxacin (24.7%), tetracyclines (21.6%) and amoxi-clav (18.5%), with no temporal trends. GR decreased from 52.2% in 2023 to 42.1% in 2025. Among the 775 shigelloses, 52.9% had AST. Resistance to amoxi-clav was 63.3% and to ampicillin 78.7%, with increasing proportions over the study-period. High proportion of the isolates were resistant to ciprofloxacin (46.3%), trimethoprim-sulfamethoxazole (49.7%) or were MDR (19.4%). GR was 90%. S. flexneri showed higher resistances to amoxi-clav (83.3%), tetracyclines (57.1%) and ampicillin (92.4%). S. sonnei showed a higher MDR proportions (29.4%).

Discussion

The high proportion of AR against amoxi-clav, ampicillin, ciprofloxacin and tetracyclines and the emergence of MDR strains for Shigella are concerning. It is necessary to increase the performance and exhaustivity of AST, promote the rational use of medicines and update clinical guidelines according to AR trends.

Key messages

• This report, based on a large number of cases studied, shows the degree of antibiotic resistance in the bacteria that most frequently cause gastrointestinal infections.

• The high rate of resistance to widely used antibiotics requires continuous adaptation of recommendations on the use of antibiotics in gastrointestinal infections.