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Empiric antibiotic use surges despite no increase in nosocomial pathogens
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The use of broad-spectrum antibiotics increased during a 5-year duration despite no increase in nosocomial pathogens, according to recent findings published in Clinical Infectious Diseases.
The rise in empiric antibiotic therapies appears to correspond with guidelines published in 2005 by the Infectious Diseases Society of America and the American Thoracic Society, which recommend empiric coverage of MRSA and Pseudomonas aeruginosa in patients at risk for health care-associated pneumonia (HCAP).
“These results suggest that the shift toward broad-spectrum antibiotics reflects a change in the threshold for treatment rather than a response to increased prevalence or enhanced ability to identify patients at risk for resistant organisms,” Barbara E. Jones, MD, MSc, from the division of pulmonary at the University of Utah and clinician at the VA Salt Lake City Health Care System, and colleagues wrote.
Jones and colleagues observed trends in antibiotic use and nosocomial pathogen identification in 95,511 veterans (median age, 71 years), and assessed how often treatment was matched with culture results. Patients included in the analysis were hospitalized for pneumonia at one of 128 VA medical centers from January 2006 through December 2010 for a median duration of 4 days.
During the study period, initial treatment with vancomycin increased from 16% to 31%, and piperacillin-tazobactam from 16% to 27%, whereas ceftriaxone treatment decreased from 39% to 33% and azithromycin from 39% to 36% (P < .001 for all). The researchers wrote that the increase in antipseudomonal coverage and MRSA treatments and slight decline in standard therapies (P < .001) could result in less coverage of more common pneumonia pathogens.
At least one blood sample (81.7% of hospitalizations) or respiratory specimen (34% of hospitalizations) was documented in 84.5% of patients within 2 days of admission. The incidence of MRSA decreased from 2.5% to 2% (P < .001), and no changes were seen in the incidence of P. aeruginosa or Acinetobacter spp.
An analysis measuring sensitivity and specificity between antibiotic coverage and culture results demonstrated a significant increase in sensitivity and a substantial decrease in specificity for MRSA (46% vs. 65%; 85% vs. 69%) and P. aeruginosa (54% vs. 63%; 76% vs. 68%), and a composite measure of both sensitivity and specificity was unchanged.
The researchers concluded that although the threshold for broad-spectrum antibiotic use has since decreased following dissemination of antimicrobial resistance guidelines, the ability to match coverage to culture results is still low, and “even with an increased caliber of the shotgun, we are still missing the mark.”
In a related editorial, Eric M. Mortensen, MD, MSc, FACP, from the Dallas VA Medical Center, noted that most studies show that typical community-acquired pneumonia (CAP) pathogens — including Streptococcus pneumoniae — are more common than HCAP, and that few patients assigned broad-spectrum antibiotic therapy demonstrate survival benefits.
“This paper reinforces that additional research is critically needed to develop reliable methods to identify those truly at risk for pneumonia due to [multidrug-resistant] pathogens,” Mortensen wrote. “It also demonstrates why every hospital needs to study their own microbiology data to identify the most common organisms for patients with outpatient-acquired pneumonia and the antibiotic resistance patterns in their patient population.”
Mortensen concluded that each hospital should discuss broad-spectrum antibiotics vs. CAP-guideline therapy with all stakeholders involved. Failure to do so will cause “even larger problems due to [multidrug-resistant] infections in the future,” he said. – by Stephanie Viguers
Disclosure s : The researchers and Mortensen report no relevant financial disclosures.
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