Findings from a Canadian study showed that increased consumption of antibiotics in hospitals was associated with increased — not decreased — antibiotic susceptibility for several important hospital pathogens.
“Widespread use of antibiotics has long been recognized as a key driver of the rise in antibiotic resistance,” researchers wrote in Infection Control and Hospital Epidemiology. “However, whether antibiotic usage in hospital contributes to hospital-specific antibiotic resistance rates has not been widely evaluated, especially at the regional level.”
The researchers analyzed data from 37 Ontario hospitals, using antibiograms to measure resistance to antibiotics and antibiotic purchasing data to indicate use. They measured the susceptibility to commonly prescribed antibiotics of several critical hospital bacteria, including the ESKAPE pathogens — Enterococcus spp., Staphylococcus aureus, Klebsiella spp., Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp. They also included Escherichia coli because it is “it represents a large proportion of all collected nosocomial bacterial isolates.”
According to the researchers, increased antibiotic consumption in the hospitals — as measured by defined daily doses per 1,000 patient-days (DDDs/1,000 PD) — predicted increased antibiotic susceptibility significantly for E. coli (0.173% per DDD/1,000 PD) and three of the six ESKAPE pathogens: Enterococcus spp. (0.309%), Klebsiella spp. (0.124%) and Enterobacter spp. (0.194%). They noted a nonsignificant increase in antibiotic susceptibility for S. aureus (0.012% per DDD/1,000 PD) and decreased antibiotic susceptibility for P. aeruginosa (0.162%). Just 23% of hospitals reported the susceptibility of A. baumannii, so it was excluded from the analysis.
Neither hospital type nor laboratory standard were significant predictors of antibiotic susceptibility, but increased hospital patient-days was, with findings suggesting that an increasing number of patient-days was associated with higher susceptibility, the researchers said.
The researchers wrote that their finding that increased hospital antibiotic use did not consistently predict resistance could have several explanations, including that many infections are likely acquired outside the hospital and antibiotic use in the hospital “would not necessarily be expected to predict hospital resistance rates.”
“Antibiograms, because of how they are calculated using patients’ initial microbial cultures, are weighted toward community-acquired pathogens. Clinicians may thus be basing their inpatient antibiotic decisions on community-weighted resistance prevalence and choosing antibiotics with less resistance among these hospital-presenting yet community-acquired pathogens, leading hospital antibiotic use to occur in response to the antibiotic resistance captured in antibiograms,” the researchers wrote. “However, a predominantly nosocomial organism such as P. aeruginosa may exhibit resistance rates that are driven by nosocomial antibiotic use.”
They concluded that further research is needed to validate their hypothesis and that their results “highlight the potential importance of community stewardship approaches on impacting antibiotic resistant organisms encountered in hospitals.” – by Gerard Gallagher
Disclosures: The authors report no relevant financial disclosures.