Outbreaks of Methicillin Resistant Staphylococcus aureus in the Neonatal Intensive Care Unit — Los Angeles County 2004

Outbreaks of Methicillin Resistant Staphylococcus aureus in the Neonatal Intensive Care Unit — Los Angeles County 2004 Page E96 D. Terashita, L. English, D. Dassey, L. Mascola, L. Yasuda Close Close preview | Purchase PDF (69 K) | Related articles | Related reference work articles AbstractAbstract BACKGROUND/OBJECTIVES: MRSA has become a large problem in NICUs in Los Angeles County (LAC). We reviewed all reported MRSA outbreaks in 2004 and assessed case characteristics, laboratory data, risk factors, and modes of transmission. METHODS: The case definition was the presence of positive cultures of MRSA from two or more infants residing in the NICU. An infant was classified as infected when MRSA was found and the infant exhibited clinical signs and symptoms of infection with no other etiologic cause; an infant was classified as colonized when MRSA was found and the infant did not exhibit clinical signs or symptoms of infection. A retrospective review of all 2004 NICU outbreaks was initiated. Twenty-seven of Los Angeles Countyʹs 104 licensed acute care hospitals (26%) have a NICU with a total of 640 beds (range 5 to 69). Basic information was gathered during the early stages of each investigation. As the investigation progressed, additional data were gathered; however, these data were not standardized from outbreak to outbreak. Significant gaps in essential information were filled with the assistance of public health nurses or with the help of the hospital infection control professional. Pulsed field gel electrophoresis (PFGE) analysis of isolates was performed at the LAC Public Health Laboratory using standard methods. PFGE pattern comparisons were performed visually. Isolates possessing indistinguishable PFGE patterns were assigned the same PFGE pattern designation. Isolates possessing different PFGE fingerprint patterns (>3 band differences from the outbreak strain) were assigned different PFGE pattern designations. RESULTS: Between January and December 2004, 9 NICUs (33%) reported nine MRSA outbreaks. There were 47 case infants; 18 infected and 28 colonized. Two infants died, one from MRSA sepsis, the other from necrotizing enterocolitis. In 1 of 6 outbreaks where PFGE was performed, the causative agent was the common LAC community-associated MRSA (CA-MRSA) PFT USA 300 strain; each outbreak demonstrated different PFGE patterns. In 2 outbreaks, transmission to the index case had an indistinguishable strain to maternal breast milk. CONCLUSIONS: We have documented MRSA as an emerging problem in this fragile population. Although the primary source of transmission was not identified in 7 of 9 outbreaks, subsequent spread is usually the result of poor infection control practices by health care workers. Utilization of molecular tests such as PFGE and assessment of infant MRSA risk factors are methods that need further exploration to prevent and control outbreaks.