Open Access Research article

Patients presenting to the hospital with MRSA pneumonia: differentiating characteristics and outcomes with empiric treatment

Emi Minejima1, Mimi Lou1, Paul Nieberg2 and Annie Wong-Beringer12*

Author Affiliations

1 University of Southern California, School of Pharmacy, 1985 Zonal Ave, Los Angeles, CA 90033, USA

2 Huntington Hospital, 100 W California Blvd, Pasadena, CA 91105, USA

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BMC Infectious Diseases 2014, 14:252  doi:10.1186/1471-2334-14-252

Published: 10 May 2014

Abstract

Background

Concern for MRSA in patients presented to the hospital with pneumonia may be overestimated leading to excessive prescribing of empiric anti-MRSA therapy. This study aims to identify at-risk patients and treatment outcomes.

Methods

Adults hospitalized during 2005–2011 with pneumonia diagnosed within 48 h of admission were included. Medical charts were retrospectively reviewed for relevant data. Patients with MRSA were matched 1:1 to those with non-MRSA pathogen or negative culture. A published risk scoring system for MRSA pneumonia was applied.

Results

268 elderly patients were included, 134 patients in each group. Compared to non-MRSA group, MRSA patients presented more acutely ill (p < 0.0001) (pneumonia severity index score, 150 vs 93; vasopressor therapy, 34% vs 6%; ICU admission, 47% vs 13%; and mechanical ventilation, 35% vs 10%) and had worse outcomes (p < 0.0001) (time to reach clinical stability, 6 vs 2.5d; length of stay, 10 vs 5d; clinical failure, 28% vs 4%; 28-day mortality, 22% vs 3%). When applied to our patients, a published risk scoring scheme had 93% sensitivity but lacked specificity at 55%; 40% of medium-risk patients did not have MRSA. A history of MRSA infection or pneumonia differentiated the latter group. Most MRSA patients (66%, 88/134) were treated empirically (primarily vancomycin) but outcome was not improved by receipt of empiric therapy.

Conclusions

Use of a published risk scoring scheme with additional variables from this study can potentially reduce overprescribing of anti-MRSA empiric therapy in patients presented to the hospital with pneumonia. Prospective studies evaluating the treatment benefit of non-vancomycin alternatives as empiric therapy are needed.

Keywords:
Pneumonia; Methicillin-resistant Staphylococcus aureus; Community-onset pneumonia; Healthcare-associated pneumonia; Risk factors