Incidence of Cefotaxime-Resistant Haemophilus influenzae Is Linked to Regional Consumption of Oral Aminopenicillins and Parenteral Third-Generation Cephalosporins in Norway.

The emergence of cefotaxime-resistant Haemophilus influenzae (CRHI) in Norway during the 2000s coincided with increased use of oral aminopenicillins and parenteral third-generation cephalosporins. This study examined associations between beta-lactam consumption and CRHI incidence. Surveillance data on antibiotic usage across Norwegian regions (2013-2017) and CRHI incidence in hospitalised patients (January 2013-March 2018) from a previous study were analysed. Correlations were calculated between average consumption rates for aminopenicillins and third-generation cephalosporins, and average CRHI incidence rates. Regional aminopenicillin prescription and hospital sales of third-generation cephalosporins varied substantially. CRHI incidence ranged from 0.8 to 3.2 cases per million inhabitants per year and was significantly associated with use of oral aminopenicillins in primary care (r = 0.88, p = 0.022), hospital use of third-generation cephalosporins (r = 0.88, p = 0.019), and both variables combined (r = 0.89, p = 0.007). The consumption variables also showed significant covariation (r = 0.88, p = 0.020). Regional variation in consumption of oral aminopenicillins and parenteral third-generation cephalosporins is linked to CRHI incidence in Norway. These findings strengthen the evidence base for avoiding unnecessary use of these agents and underscore the need for coordinated antibiotic stewardship across healthcare sectors to limit resistance development.