Epidemiological Data and Antimicrobial Resistance of Campylobacter spp. in Portugal from 13 Years of Surveillance

Abstract

This study extensively analyzed campylobacteriosis surveillance in Portugal from 2009 to 2021, aiming to investigate demographic shifts, seasonal variations, and antimicrobial resistance (AMR) within Campylobacter isolates. Surveillance network and sentinel laboratory-based system data revealed a substantial under-notification of campylobacteriosis cases, suggesting an underestimated disease burden. Notification rates exhibited a paradigm shift, with a notable prevalence among the pediatric population, particularly in children aged 1-4 years, diverging from European reports. Additionally, an emerging trend of Campylobacter infections in younger adults (15-44 years) was observed. The study unveiled a unique seasonal distribution of cases, defying typical summer peaks seen elsewhere. AMR analysis revealed high resistance to ciprofloxacin and tetracycline, in both C. jejuni (93.7% and 79.2%, respectively) and C. coli (96.5% and 93.2%, respectively), stable throughout the studied period (2013-2021). C. coli exhibited significantly higher resistance to erythromycin, gentamicin, ampicillin and ertapenem compared to C. jejuni (p < 0.001). Multilocus Sequence Typing (MLST) data demonstrated the distribution of resistance markers across diverse sequence types, challenging the notion of a clonal origin for multidrug-resistant isolates. In conclusion, the study highlights the need for enhanced surveillance and raises concerns about alarming AMR levels, recommending the implementation of whole-genome sequencing (WGS)-based surveillance for a deeper comprehension of disease patterns and an evolving AMR landscape.

Keywords: Campylobacter infection; WGS; antibiotic resistance; epidemiology; notification; resistance genetic determinants; surveillance.

Figure 1

Distribution of the number of cases of Campylobacter infections according to the month of sampling, considering the total of cases received in the NRL in the most representative period spanning from 2015 to 2021.

Figure 2

Percentage of cases of Campylobacter infections by age group (in years) in the time period spanning from 2009 to 2021.

Figure 3

Proportion of Campylobacter spp. isolates that are multidrug resistant (MDR), resistant to one and/or two antimicrobials and completely susceptible, while considering the four priority antimicrobials (CIP—ciprofloxacin, ERY—erythromycin, TET—tetracycline, GEN—gentamicin).

Figure 4

Evolution of the resistance rate for Campylobacter jejuni (at the left) and Campylobacter coli (at the right) to the four priority antimicrobials (CIP, ERY, TET, GEN), from 2013 to 2021.

Figure 5

Multilocus Sequence Typing-based phylogenetic tree of 136 Camplylobacter coli isolates from 2016 to 2021. Neighbor-joining tree was reconstructed based on MLST profile data using GrapeTree [20]. Each node, corresponding to an isolate, is colored according to MLST clonal complex. Sequence type (ST) is indicated next to the isolate’s ID. Metadata blocks, from inner to outer, display (i) isolation year and presence of AMR-associated genetic markers for (ii) ciprofloxacin, (iii) tetracycline, (iv) streptomycin, and (v) erythromycin.

Figure 6

Multilocus Sequence Typing-based phylogenetic tree of 244 Camplylobacter jejuni isolates from 2016 to 2021. Neighbor-joining tree was reconstructed based on MLST profile data using GrapeTree [20]. Each node, corresponding to an isolate, is colored according to MLST clonal complex. Sequence type (ST) is indicated next to the isolate’s ID. Metadata blocks, from inner to outer, display (i) isolation year and presence of AMR-associated genetic markers for (ii) ciprofloxacin, (iii) tetracycline, (iv) streptomycin, and (v) erythromycin.