Seasonal Changes in the Prevalence of Antibiotic-Susceptible Acinetobacter calcoaceticus-baumannii Complex Isolates Result in Increased Multidrug Resistance Rates During Winter Months.

Temporal analysis of Acinetobacter calcoaceticus-baumannii complex isolates in a large, US healthcare system demonstrated decreased occurrence of antibiotic-susceptible isolates between November and May, while resistant isolate occurrence was temporally stable. This resulted in 50%-100% seasonal increases of resistance rates. This work offers insight into the phenomenon of Gram-negative pathogen seasonality.