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.