Relationship of Vancomycin Minimum Inhibitory Concentration to Mortality in Patients With Methicillin-Resistant Staphylococcus aureus Hospital-Acquired, Ventilator-Associated, or Health-care-Associated Pneumonia

March 25, 2011 at 2:56 pm Leave a comment

Chest Dec 2010 V.138 N.6 p.1356-62

Nadia Z. Haque, PharmD, Lizbeth Cahuayme Zuniga, MD, Paula Peyrani, MD, Katherine Reyes, MD, Lois Lamerato, PhD, Carol L. Moore, PharmD, Shruti Patel, MD, Marty Allen, MD, Edward Peterson, PhD, Timothy Wiemken, MPH, Ennie Cano, PharmD, Julie E. Mangino, MD, Daniel H. Kett, MD, Julio A. Ramirez, MD, Marcus J. Zervos, MD and the Improving Medicine through Pathway Assessment of Critical Therapy of Hospital-Acquired Pneumonia (IMPACT-HAP) Investigators

From the Henry Ford Health System (Drs Haque, Cahuayme Zuniga, Reyes, Lamerato, Moore, Patel, Peterson, and Zervos), and the School of Medicine (Dr Zervos), Wayne State University, Detroit, MI; the University of Louisville (Drs Peyrani, Allen, and Ramirez and Mr Wiemken), Louisville, KY; the Ohio State University (Dr Mangino), Columbus, OH; and the University of Miami Miller School of Medicine and Jackson Memorial Hospital (Drs Cano and Kett), Miami, FL.

Abstract

Background

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of hospital-acquired pneumonia (HAP), ventilator-associated pneumonia (VAP), and health-care-associated pneumonia (HCAP). These infections are associated with significant morbidity, mortality, and cost. The impact of vancomycin minimum inhibitory concentration (MIC) on mortality for patients with MRSA pneumonia has not been determined.

Methods

Adult patients in ICUs with a diagnosis of MRSA HAP, VAP, or HCAP were entered in the study. Clinical and laboratory information were prospectively collected. Vancomycin MIC and heteroresistance were determined for each MRSA isolate. Data were collected from February 2006 through August 2007. The primary outcome variable was all-cause mortality at day 28. A propensity score approach was used to adjust for confounding variables.

Results

The study sample consisted of 158 patients. All-cause mortality at day 28 was 32.3%. The majority of MRSA isolates had a vancomycin MIC ≥ 1.5 mg/mL (115/158, 72.8%). Propensity score analysis demonstrated an increase in 28-day mortality as vancomycin MIC increased from 0.75 to 3 mg/mL (P ≤ .001). Heteroresistance to vancomycin, demonstrated in 21.5% isolates, was not associated with mortality.

Conclusions

Mortality in patients with MRSA HAP, VAP, and HCAP increases as a function of the vancomycin MIC, even for strains with MIC values within the susceptible range. Evaluation of vancomycin MICs should be contemplated at the institutional level and for individual cases of MRSA pneumonia. The use of vancomycin therapy in patients with MRSA pneumonia caused by isolates with MICs between 1 and 2 mg/mL should be undertaken with caution, and alternative therapies should be considered.

Footnotes

Part of this article was published previously in abstract form (Haque NZ, Cahuayme Zuniga L, Osaki Kiyan P, et al; IMPACT-HAP Study Group. Relationship of MIC to vancomycin on outcome of methicillin-resistant Staphylococcus aureus health care-associated and hospital-acquired pneumonia. In: 48th Annual ICAAC/IDSA 46th Annual Meeting; October 25-28, 2008; Washington, DC. Abstract K-531).

Funding/Support: This work was supported by a grant from Pfizer Inc US Medical.

abstract

http://chestjournal.chestpubs.org/content/138/6/1356.abstract

Entry filed under: Antimicrobianos, Bacterias, Bacteriemias, Epidemiología, Health Care-Associated Infections, Infecciones respiratorias, Metodos diagnosticos, Resistencia bacteriana.

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