Adverse health events associated with antimicrobial drug resistance in Campylobacter species:: A registry-based cohort study

Background. Resistance to clinically important antimicrobial agents, particularly fluoroquinolones and macrolides, is increasing among Campylobacter isolates, but few studies have explored the human health consequences of such resistance. Methods. In a registry-based cohort study, we determined the risk of invasive illness and death associated with infection with quinolone- and erythromycin-resistant Campylobacter strains, while adjusting for comorbidity. We linked data from the Danish Surveillance Registry for Enteric Pathogens with data from the Civil Registration System and National Health Registries. Results. Of 3471 patients with Campylobacter infection, 22 ( 0.63%) had an adverse event, defined as invasive illness or death, within 90 days of the date of receipt of samples. Patients infected with quinolone- resistant Campylobacter strains had a 6-fold increased risk of an adverse event within 30 days of the date of receipt of samples, compared with patients infected with quinolone- and erythromycin-susceptible Campylobacter strains ( adjusted odds ratio [AOR], 6.17 [95% confidence interval {CI}, 1.62 - 23.47]). However, infection with erythromycin-resistant strains was associated with a >5-fold risk of an adverse event within 90 days of the date of receipt of samples ( AOR, 5.51 [ 95% CI, 1.19 - 25.50]). Conclusions. The present study provides evidence of the human health consequences of resistance to clinically important agents among Campylobacter infections and the need for increased efforts to mitigate such resistance.