Risk factors for development of methicillin-resistant Staphylococcus aureus infection among colonized patients.

BACKGROUND: This study was conducted to identify clinical factors associated with development of infection caused by methicillin-resistant Staphylococcus aureus (MRSA) among hospitalized patients with nasal MRSA colonization. METHODS: We conducted a prospective cohort with nested case-control study at a 672-bed, public, academic hospital in Dallas, Texas. The study duration was from January 1, 2008, to July 28, 2009. From the cohort of patients who had presence of nasal colonization with MRSA at admission, we identified patients who developed subsequent infection with MRSA during a 3-month period. We compared these patients (cases) with colonized patients who remained uninfected (controls; 2 controls per case). We collected demographic and clinical data and performed statistical analyses. RESULTS: During the 19-month study period, 426 patients were found to have nasal colonization with MRSA. Of these, 36 (8.5%) developed a subsequent infection with MRSA within 3 months. When these 36 cases were compared with 72 controls, the factors independently associated with the development of subsequent infection were development of pressure ulcer during hospital stay (adjusted odds ratio, 5.82; 95% confidence interval: 2.21-15.31; P value=.000) and preadmission steroid therapy (adjusted odds ratio, 13.2; 95% confidence interval: 2.44-70.97; P value=.003). CONCLUSION: History of steroid therapy prior to admission and development of pressure ulcer are associated with increased risk of subsequent MRSA infection in patients nasally colonized with MRSA.

Controlling outbreak of vancomycin-resistant Enterococcus faecium among infants caused by an endemic strain in adult inpatients.

BACKGROUND: Vancomycin-resistant Enterococcus faecium (VREfm) is commonly associated with hospital outbreaks and has been found to be associated with increased morbidity, mortality, length of stay, and health care costs. METHODS: We sought to investigate and control an outbreak of VREfm in the neonatal intensive care unit (NICU) of a public academic hospital with a level III NICU. The index case was an infant in the NICU incidentally identified with urinary colonization with VREfm. Aggressive control measures were initiated promptly. Investigation included active surveillance cultures in infants, parents of colonized infants, and birth mothers of newborn admitted to NICU; molecular strain typing of available isolates of VREfm including adult inpatients; and medical record review. RESULTS: After identification of index case, 13 additional infants were identified with VREfm colonization. Age at culture was 6 to 87 days; birth weight was 1,070 to 2,834 g. VREfm isolated from majority of infants (12/14 [85.7%]), the birth mother of a pair of colonized twins, and a pulse oximeter device used in adult inpatients belonged to a single strain. Outbreak control measures were successful in the NICU. The outbreak-causing strain was found to be endemic among adult inpatients. Adult patients with the outbreak-causing strain of VREfm were more likely to have received previous therapy with meropenem (Mann-Whitney 2-tailed P value = .038). VRE colonization was identified in 0.3% (1/310) of birth mothers with newborn admitted to NICU. CONCLUSION: An endemic strain of VREfm among adult inpatients was responsible for a subsequently controlled outbreak in the NICU.

Aerosolization of methicillin-resistant Staphylococcus aureus during an epidemic in a burn intensive care unit.

Despite prompt identification of cases, rigorous isolation techniques, negative environmental samples, and largely negative personnel cultures, an epidemic of methicillin-resistant Staphylococcus aureus (MRSA) continued in our Burn Intensive Care Unit (BICU). We sought to determine whether there was any aerosolization of that organism in the unit and if there were air quality characteristics that might have enabled its transmission to patients. We measured air exchange and flow rates into rooms and using a Burkhard air sampler measured MRSA generated inside and just outside the rooms before, during, and after dressing changes in burned patients and in controls. We compared MRSA colonization and disease rates in the BICU before and after renovation. Airflow in rooms was variable with positive pressure rooms found adjacent to negative pressure rooms. In the rooms of patients with burns and MRSA infections, MRSA was found by the air sampling machine at four equidistant parts of the rooms and just outside the door during dressing changes and in one instance before a dressing change. Control patients had negative cultures. After renovation that allowed door closure during dressing changes, increased space per patient and improved indoor air quality, there was a sustained fall in MRSA cases. Dressing changes in MRSA infected burned patients generate infectious aerosols. Knowledge and consideration of that fact greatly influenced renovation of our BICU. Along with other infection control measures, this has led to a decreased number of patients with MRSA colonization and disease.