Risk factors for treatment failure in patients receiving vancomycin for hospital-acquired methicillin-resistant Staphylococcus aureus pneumonia.

Aston JL, Dortch MJ, Dossett LA, Creech CB, May AK
Surg Infect (Larchmt). 2010 11 (1): 21-8

PMID: 19689198 · DOI:10.1089/sur.2008.100

BACKGROUND - The rate of vancomycin failure in patients with hospital-acquired pneumonia (HAP) caused by methicillin-resistant Staphylococcus aureus (MRSA) has exceeded 40% in several studies. This observation was attributed initially to the lack of weight-based dosing and targeting of lower trough concentrations. However, a subsequent study demonstrated no additional benefit in patients who achieved trough vancomycin concentrations >15 mg/L compared with patients with concentrations between 5 and 15 mg/L. We sought to identify contributors to vancomycin failure in patients with MRSA HAP.

METHODS - This was a retrospective study of patients in a surgical intensive care unit with MRSA HAP who received vancomycin between January 1, 2005, and July 31, 2007. Clinical outcomes, microbiological data, prior antibiotic exposure, ventilator days, co-morbidities, and demographics were compared in patients with clinical success and those with treatment failure. Their characteristics were compared using a two-sided Fisher exact test or Mann-Whitney U test, as appropriate for nominal or continuous data.

RESULTS - More patients in the treatment failure group had received one or more doses of vancomycin within 90 days leading up to MRSA HAP (84% vs. 47%; p = 0.04). In addition, the duration of prior vancomycin exposure was significantly longer among patients in the treatment failure group (6 vs. 0 days; p < 0.05). There were no statistically significant differences in the percentages of patients who achieved a vancomycin trough concentrations > or =15 mg/dL within the first 48 h (28% vs. 17%; p = 0.69), 72 h (44% vs. 39%; p = 1.0), or 96 h (56% vs. 44%; p = 0.74) after starting treatment. Patients in the failure group had a significantly higher overall mortality rate (32% vs. 0; p = 0.02).

CONCLUSIONS - These data suggest that patients who have recent exposure to vancomycin are at high risk for vancomycin failure and may benefit from an appropriate alternative when a diagnosis of MRSA HAP is made.

MeSH Terms (16)

Aged Animals Anti-Bacterial Agents Critical Care Cross Infection Drug Utilization Female Humans Male Methicillin-Resistant Staphylococcus aureus Middle Aged Pneumonia, Staphylococcal Retrospective Studies Risk Factors Treatment Failure Vancomycin

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