NEW ORLEANS, LA—Overprescription of antibiotics in the intensive care unit (ICU) for patients with community-acquired pneumonia (CAP) “remains a significant problem,” according to authors of a study presented at IDWeek 2016.

“Our study shows that in patients admitted with CAP to the ICU, P. aeruginosa is rare and coverage against this organism may not be indicated in the absence of cystic fibrosis or prior pseudomonal infection,” said lead study author Rorak Hooten, MD, from the University of Arizona in Tucson, AZ. 

“Our results suggest that coverage against MRSA [methicillin-resistant Staphylococcus aureus] be reserved for selected patients, such as those with necrotizing pneumonia and/or a history of positive MRSA swab,” he said.

The Infectious Diseases Society of America (IDSA) currently recommends adding vancomycin to the standard fluoroquinolones or beta-lactam + macrolide inpatient therapy for patients with CAP in the ICU in order to address MRSA. Many clinicians also prescribe antibiotics for Pseudomonas aeruginosa, he noted.

But it is unclear whether or not MRSA coverage is needed for all patients with CAP. So the study authors conducted a retrospective records review to evaluate the prevalence of MRSA and P. aeruginosa, and antibiotic coverage, among CAP patients admitted to the ICU. 

The review included 146 patients who had CAP and were admitted to the ICU at the University of Arizona during 2013 and 2014. History of recent influenza was noted in 3 patients (2%) and 51 patients (26.7%) had chronic obstructive pulmonary disease. Seven patients (8%) had a history of positive MRSA nasal screen.

Respiratory samples were collected from 80 patients of which 6 were positive for MRSA, 1 was positive for P. aeruginosa, and 12 were positive for Streptococcus pneumoniae, Dr. Hooten reported. 

One hundred and thirty-six (93%) patients received antibiotics: 50.7% received coverage against MRSA, 57.5% received coverage against P. aeruginosa, and 78.1% received coverage against atypical strains. 

“In our multivariate model, the factors associated with MRSA pneumonia were necrotizing pneumonia and positive MRSA swab,” Dr. Hooten noted. “Readmission, late intubation, and escalation of care were not associated with coverage against MRSA or P. aeruginosa.”