Culture-based detection of methicillin-resistant Staphylococcus aureus by a network of European laboratories: an external quality assessment study

Abstract

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 10(7)-1 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 11-20% to 61-70%. MRSA carriage rates were less variable (0-20%) between countries. Almost all participants (n=22, 96%) screened patients for MRSA carriage during 2009-2010, 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.

Occurrence of methicillin-resistant Staphylococcus aureus in farm workers and the livestock environment in Mecklenburg-Western Pomerania, Germany

“…Double selective enrichment was chosen to process dust samples and poultry oropharyngeal swabs, as the assumed density of MRSA might be very small. In contrast, no selective enrichment was used for nasopharyngeal swabs from humans, as detection rates were previously shown to be at a good level [ 49 ],[ 50 ]. Nevertheless, more anatomical sample sites including, for instance, the perineum, could have led to higher detection rates [ 51 ],[ 52 ].…”

The Association Between Colonization With Carbapenemase-Producing Enterobacteriaceae and Overall ICU Mortality

“…Species identification was done with the Vitek 2 system (bioMérieux, Marcy l’Etoile, France). Isolates with nonsusceptibility to at least one of the carbapenems ertapenem, imipenem, and meropenem according to European Committee on Antimicrobial Susceptibility Testing criteria ( http://www.eucast.org ) were subjected to phenotypic detection of MBLs (double disk synergy test with disks containing imipenem, ceftazidime, and EDTA), KPCs (combined-disk test with disks containing imipenem and meropenem, and both supplemented with phenylboronic acid), and OXA-48 (temocillin disk test) ( 6 , 19 , 20 ). All of the isolates with phenotypes indicative of being CPE were subjected to polymerase chain reactions specific for bla KPC -, bla IMP -, bla VIM -, bla NDM -, and bla OXA-48 -like genes ( 21 – 24 ).…”

Variable performance of models for predicting methicillin-resistant Staphylococcus aureus carriage in European surgical wards

“…Screening specimens were processed in local microbiology laboratories which participated in an external quality assurance program [22]. Confirmation of MRSA identification and susceptibility testing was also performed at the study’s central laboratory at the University of Antwerp, Belgium.…”