Severity of disease and clinical outcomes in patients with hospital-acquired pneumonia due to methicillin-resistant Staphylococcus aureus strains not influenced by the presence of the Panton-Valentine leukocidin gene.

BACKGROUND: Patients with community-acquired pneumonia (CAP) infected with methicillin-resistant Staphylococcus aureus (MRSA) strains carrying the Panton-Valentine leukocidin (PVL) gene have severe clinical presentation and poor clinical outcomes. Antibiotics that suppress toxin production have been suggested for the management of these patients. The objective of this study was to compare the severity of disease and clinical outcomes of patients with hospital-acquired pneumonia/ventilator-associated pneumonia (HAP/VAP) infected with MRSA carrying the PVL gene with those patients infected with MRSA strains that do not carry the PVL gene. METHODS: This was a multicenter observational study of patients with HAP and VAP. MRSA isolates were subjected to genetic analysis to define the presence of the PVL gene, the USA type and the staphylococcal cassette chromosome mec type. Severity of disease was evaluated with the Acute Physiology and Chronic Health Evaluation II (APACHE II) score. The primary clinical outcome was mortality at hospital discharge. RESULTS: A total of 109 cases of MRSA HAP/VAP were evaluated. The incidence of PVL(+) MRSA was 27%. APACHE II score at diagnosis of HAP/VAP was 21 ± 8 for PVL(+) MRSA and 20 ± 6 for PVL(-) MRSA (P = .67). Mortality was 10% (3/29) for patients with PVL(+) MRSA versus 10% (8/80) for patients with PVL(-) MRSA (P > .99). CONCLUSIONS: In patients with HAP or VAP due to MRSA, severity of disease and clinical outcomes are not influenced by the presence of the PVL gene. Therapeutic strategies directed to block PVL exotoxin may not impact outcomes in these patients.

Relationship of vancomycin minimum inhibitory concentration to mortality in patients with methicillin-resistant Staphylococcus aureus hospital-acquired, ventilator-associated, or health-care-associated pneumonia.

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.

Incidence, etiology, timing, and risk factors for clinical failure in hospitalized patients with community-acquired pneumonia.

BACKGROUND: The etiology of clinical failure in hospitalized patients with community-acquired pneumonia (CAP) may be related or unrelated to pulmonary infection. The objective of this study was to define the incidence, etiology, timing, and risk factors associated with clinical failures related to CAP vs those unrelated to CAP. METHODS: Observational retrospective study of consecutive CAP patients. All patients who experienced clinical failure were identified. Cases were presented to a review committee that defined, by consensus, etiology, timing, and risk factors for clinical failures related to CAP. RESULTS: Among 500 patients who were enrolled in the study, clinical failure was identified in 67 (13%). Clinical failure was related to CAP in 54 patients (81%). The most common etiologies for clinical failure related to CAP were severe sepsis (33%), acute myocardial infarction (28%), and progressive pneumonia (19%). All cases of severe sepsis occurred in the first 72 h of hospitalization. The most common etiology for clinical failure unrelated to CAP was the development of hospital-acquired pneumonia (45%). At the time of hospital admission, factors associated with clinical failure related to CAP were advanced age, congestive heart failure, hypotension, abnormal gas exchange, acidosis, hypothermia, thrombocytopenia, and pleural effusion. CONCLUSIONS: The development of severe sepsis early during hospitalization is the primary etiology for clinical failure related to CAP. To achieve early treatment intervention, physicians should maintain a high index of suspicion for severe sepsis in hospitalized patients with CAP. To decrease the number of clinical failures unrelated to CAP, interventions need to be developed at the local level to improve the processes of care for patients with pneumonia.

Infections due to community-acquired methicillin-resistant Staphylococcus aureus: an emergent epidemic in Kentucky.

In recent years, epidemics of Methicillin-Resistant Staphylococcus aureus (MRSA) infections in patients not associated with the health care system have been reported in several states. This community-acquired MRSA (CA-MRSA) is microbiologically distinct from hospital-acquired MRSA (HA-MRSA) and has a predilection to cause severe skin and soft tissue infections and a particularly virulent necrotizing pneumonia. Many patients have suffered serious morbidity and mortality because of thefailure to recognize CA-MRSA as the pathogen in these infections. There are also serious infection control implications associated with these epidemics. Here we report 15 cases of CA-MRSA infections managed by the Infectious Diseases Division at the University of Louisville and offer guidelines for diagnosis, treatment, and infection control based on our experience. Primary care and emergency physicians as well as infection control professionals need to be aware that there is an emerging epidemic of CA-MRSA infections in the state of Kentucky. Several of our current practices regarding treatment and isolation will need to be modified to prevent the morbidity and possibly mortality associated with some CA-MRSA infections.