Culture-based detection of methicillin-resistant **Staphylococcus aureus** by a network of European laboratories: an external quality assessment study
Faculty of Medicine and Health Sciences
European journal of clinical microbiology and infectious diseases. - Wiesbaden
, p. 1765-1770
University of Antwerp
Twenty-three hospital laboratories from Europe and Israel participated in an external quality assessment (EQA) of the culture-based detection of methicillin-resistant Staphylococcus aureus (MRSA). Participants also reported the MRSA prevalence in clinical cultures and patient screening specimens, as well as the MRSA screening practices employed at their hospitals. An EQA panel of 18 samples consisting of two MRSA harbouring SCCmec IV and I, and one strain each of methicillin-resistant coagulase-negative S. epidermidis, methicillin-sensitive S. aureus and Escherichia coli as pure strains or in mixtures at 1071 cfu absolute loads was analysed by the 23 participants. Seventeen (74%) participants identified 17 or more samples correctly. Of these, 15 (88%) utilised a chromogenic medium alone (ChromID, bioMérieux; BBL CHROMagar, BD Diagnostics; MRSA Select, Bio-Rad Laboratories) or combined with a conventional medium and up to three confirmatory tests. Proportions of MRSA among S. aureus isolated from clinical cultures varied widely, even among hospitals within countries, ranging from 1120% to 6170%. MRSA carriage rates were less variable (020%) between countries. Almost all participants (n = 22, 96%) screened patients for MRSA carriage during 20092010, of which 15 (68%) screened intensive care unit (ICU) patients alone or combined with other targeted high-risk groups, and 10 (45%) combined nasal screening with another body site.