Staphylococcus aureus antimicrobial susceptibility of abscess samples from adults and children from the Kaleida Health System in western New York State, 2003 to 2006.

Staphylococcus aureus is the most common etiologic agent of skin abscesses. The regional rate of methicillin-resistant S. aureus (MRSA) abscesses may reflect the prevalence of local community-acquired MRSA (CAMRSA). A retrospective study was conducted to compare the antimicrobial susceptibility patterns of S. aureus isolates recovered from abscesses from 2003 to 2006 from patients at hospitals of the Kaleida Health System in western New York. S. aureus susceptibility information was obtained from a Vitek Legacy system, and the location and source of each isolate were identified. EpiInfo software was used to analyze the antimicrobial susceptibilities of all isolates and the trends in the rates of MRSA. A total of 2,848 S. aureus abscesses were identified by the Kaleida Health Clinical Microbiology Laboratory. Of those, 978 S. aureus abscess events occurred in four hospitals, including three adult facilities (547 episodes with 62 cases of bacteremia) and one children's facility (431 episodes with 2 cases of bacteremia). The MRSA rates in adults increased from 56% (2003) to 71% (2006), and that in children increased from 26% (2003) to 64% (2006). Of the MRSA isolates in the children's samples, more than 92% were susceptible to clindamycin. Of the MRSA isolates in the adult samples, 50% were susceptible to clindamycin in 2003 and 2004, whereas greater than 75% were susceptible in 2005 and 2006. The increased rates of MRSA abscesses with susceptibility to clindamycin may reflect the high prevalence level of CAMRSA in the western New York community. The variations in S. aureus susceptibilities could serve as an indicator of the changing resistance patterns within a broad urban community.

Pitfalls in the diagnosis of enteroviral infection in young children.

BACKGROUND: Three infants with enteroviral infections were admitted to a neonatal intensive care unit (NICU). Investigation into the possible nosocomial spread of enterovirus identified 31 other infected infants. Only 1 of the 31 was truly positive; 30 were false-positive results. METHODS: This was a retrospective observational study. Investigational laboratory studies were conducted to identify problems in diagnostic procedures. RESULTS: Stool cultures were used to identify asymptomatic infections. Investigation identified several problems in the procedures in identification of enterovirus: (1) stool specimens were not properly filtered, (2) insufficient number of tissue culture cell types were used, (3) nonspecific toxicity due to stool and the presence of Clostridia difficile toxin was responsible for cytopathic effects in tissue culture, (4) the failure to block nonspecific fluorescent staining led to misidentification of enteroviruses. CONCLUSIONS: The use of stool cultures to identify asymptomatic enteroviral infections in infants in an NICU can be fraught with problems because of high frequency of C. difficile toxin and the nonspecific toxic effects of stool on tissue culture cells. These problems can be rectified when proper procedures are followed.