The femAB operon is involved in the formation of the characteristic pentaglycine side chain of the staphylococcal peptidoglycan. Allele replacement of the femAB operon with the tetracycline resistance determinant tetK in a methicillin-resistant Staphylococcus aureus strain resulted in impaired growth, methicillin hypersusceptibility, and lysostaphin resistance. The usual pentaglycine cross-bridges were replaced by monoglycine bridges exclusively, and cross-linking of the peptidoglycan strands was drastically reduced. Complementation of the femAB null mutant by either femA or femAB resulted in the extension of the cross-bridges to a triglycine or a pentaglycine, respectively. This finding suggests that FemA is responsible for the formation of glycines 2 and 3, and FemB is responsible for formation of glycines 4 and 5, of the pentaglycine side chain of the peptidoglycan precursor. Moreover, it can be deduced that addition of the first glycine must occur by a femABindependent mechanism.The chromosomal femAB operon belongs to the Staphylococcus aureus housekeeping genes and is found in all S. aureus strains (15, 18), and femAB alleles similar in organization and sequence were identified in Staphylococcus epidermidis and Staphylococcus haemolyticus (1). The operon arose by gene duplication and codes for two similar cytoplasmic proteins that are produced mainly during the exponential phase (7, 16). FemA and FemB are involved in a yet unknown way in the formation of the pentaglycine side chain that is attached to the L-lysine of the peptidoglycan stem peptide (7,14,21). This long and flexible pentaglycine peptide allows the high cross-linking between the peptide moiety of the single peptidoglycan strands observed in S. aureus cell walls. While FemB-less cells are able to form only triglycine cross-bridges, the cell wall composition of leaky femAB mutants suggests that FemA might be responsible for the addition of the second and third glycine residues (9, 14). A femAB null mutant would be expected to attach only a single glycine to the stem peptide, and it was questionable if such a mutant would be still viable.The consequences of either femB inactivation or lowering of femAB transcription are pleiotropic. Besides the reduction of the glycine content of the cell walls, overall peptidoglycan cross-linking and cell wall turnover are reduced, there is an aberrant cell septum formation, and cell separation is retarded (13,14,21). Methicillin resistance in S. aureus is abolished, and ␤-lactam susceptibility in susceptible strains is increased. The production of the low-affinity penicillin-binding protein PBP2Ј in methicillin-resistant (Mc r ) strains, the prerequisite for methicillin resistance, is thereby not affected (6), suggesting that PBP2Ј is unable to function properly in femAB mutants. This makes FemA and/or FemB suitable targets for inhibitors which could restore the efficacy of ␤-lactam antibiotics against Mc r strains. The construction of a femAB null mutant is the first step in unravelling the biological function...

These results demonstrate that education on the proper technique for using hand rub, as outlined in EN 1500, can significantly increase the degree of bacterial killing.

Pulsed-field gel electrophoresis (PFGE) is considered the "gold standard" for molecular typing of methicillin-resistant Staphylococcus aureus (MRSA). However, the method is time-consuming and expensive, and its discriminatory power may not be necessary in outbreak situations. We used a rapid multiplex PCR-based method with published primers and compared the results with those obtained by PFGE. A total of 75 clinical isolates were typed: 59 strains originated from our prospectively collected clinical strains and were epidemiologically unrelated; 16 strains came from an outbreak that was epidemiologically well defined in time and space. A primer mix of the spa gene, the coa gene, and the hypervariable region adjacent to mecA gene was used for multiplex PCR. Both PFGE and PCR clustered the 75 strains into 41 different genotypes. Concordance of the results was 100% for strains originating from the outbreak. Overall, both methods produced concordant results in 72% of cases. A total of 16% were clustered together by PFGE, but not by PCR and 12% were clustered together by PCR but not by PFGE, respectively. The turnaround time was only 8 h for PCR but 5 days for PFGE. This PCR-based method is excellent for rapid and inexpensive typing of MRSA in an outbreak setting, but the discriminatory power and reproducibility are still insufficient to replace PFGE in longitudinal studies in the endemic setting.Nosocomial infections caused by methicillin-resistant strains of Staphylococcus aureus (MRSA) belong to the most important multiresistant pathogens worldwide (5). Monitoring and limiting the intra-and interhospital spread of MRSA strains requires the use of rapid and accurate epidemiologic typing systems. The emergence of recently documented vancomycinresistant S. aureus (VRSA) amplifies the need for control of MRSA and VRSA (2). Some MRSA strains, epidemic MRSA, have been observed to disseminate quickly (7). Their prompt identification is crucial to control and eradicate an outbreak, while saving resources for unnecessary isolations of patients unrelated to an outbreak. A large number of molecular methods have been developed for typing MRSA strains. DNA fingerprinting by pulsed-field gel electrophoresis (PFGE) is considered to be one of the most reliable, discriminatory, and reproducible typing procedures to allow the detection of high degree DNA polymorphism (8,10,14,(21)(22)(23)), but it is technically demanding, time-consuming, and expensive. In an outbreak setting a rapid typing tool should allow one to cluster epidemiologically linked cases and separate them from sporadic cases.The aim of the present study was to adapt a rapid PCR method to investigate MRSA strains in an outbreak setting. We compared PCR results from epidemiologically well-defined unrelated strains and outbreak strains with the results of PFGE. MATERIALS AND METHODS Bacterial isolates.A total of 75 MRSA isolates were investigated. Of these, 59 isolates originated from our prospectively collected epidemiologically unrelated clinical isolates; no associat...

The estimated rate of spread of ESBL-producing Enterobacteriaceae-in particular, Escherichia coli-was low in a tertiary care university-affiliated hospital with high levels of standard hygiene precautions. The low level of nosocomial transmission and the rapid emergence of community-acquired ESBL challenge the routine use of contact isolation in a non-epidemic setting, saving resources and potentially improving patient care.

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