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Gram-negative antibiotic resistance increases in winter months
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The prevalence of antibiotic-susceptible Acinetobacter calcoaceticus-baumannii complex isolates changes seasonally, with increased rates of multidrug resistance observed during the winter months, possibly due to increases in antibiotic prescriptions in the outpatient setting, researchers reported.
“Our study is limited by its retrospective, single-regional health care system design. However, our findings are consistent with findings from other international studies; thus, we predict that the phenomenon we observed is generalizable,” Juan J. Calix, MD, PhD, a third-year fellow in the division of infectious diseases at Washington University School of Medicine in St. Louis, told Infectious Disease News.
“As ID physicians, being aware that multidrug resistance rates exhibit seasonal fluctuations should help to guide decisions regarding empiric antibiotic therapies.”
The incidence of many gram-negative pathogens, including Acinetobacter calcoaceticus-baumannii complex (Abc), increases during summer or warmer months, Calix and colleagues noted.
“Accurate characterization of these seasonal trends is important for effective surveillance and infection control efforts. However, reports from single center studies conflict on Abc seasonality,” they wrote.
Therefore, Calix and colleagues conducted a retrospective analysis of 1,948 Abc clinical isolates identified between Jan. 1, 2007, and Dec. 31, 2016, in 11 hospitals within the BJC HealthCare system.
According to the study, which was published in Open Forum Infectious Diseases, they plotted the 10-year cumulative total of isolates collected in each month and grouped them based on susceptibility to gentamicin, carbapenems, fluoroquinolones or trimethoprim-sulfamethoxazole.
Between June and November, they observed a peak in susceptible isolates but no corresponding peak in resistant isolates. As a result of this trend, September or October typically demonstrated the lowest net of antibiotic resistance rates, whereas the rates of net antibiotic resistance were highest in February.
According to the study, resistance rates were lower between June and November when compared with rates between December and May.
The researchers suggested that winter-associated increases in outpatient antibiotic prescriptions may be a driver behind the seasonality of Abc and the winter-associated increase in gram-negative antibiotic resistance rates.
“Though it is still too early attribute fluctuations in multidrug resistance rates to these seasonal prescription practices, this link needs to be further explored as a possible important strategy in our fight to control antibiotic resistance,” Calix said. “It should at least offer pause to all medical providers who are considering prescribing unnecessary antibiotics during cold season.” – by Marley Ghizzone
Disclosures: Calix reports no relevant financial disclosures. Pleases see the study for all other authors’ relevant financial disclosures.
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