Search

Recurrence of osteomyelitis by the same bacterial strain is well known. We report three patients with a second episode of osteomyelitis at the same site caused by different strains of bacteria from the original. Formerly infected and altered bone surface might present a region of diminished resistance for a new infection.

Objectives The development of daptomycin resistance in Staphylococcus aureus is associated with clinical treatment failures. The mechanism(s) of such resistance have not been clearly defined. Methods We studied an isogenic daptomycin-susceptible (DAPS) and daptomycin-resistant (DAPR) S. aureus strain pair (616; 701) from a patient with relapsing endocarditis during daptomycin treatment, using comparative transcriptomic and proteomic techniques. Results Minor differences in the genome content were found between strains by DNA hybridization. Transcriptomic analyses identified a number of genes differentially expressed in important functional categories: cell division; metabolism of bacterial envelopes; and global regulation. Of note, the DAPR isolate exhibited reduced expression of the major cell wall autolysis gene coincident with the up-regulation of genes involved in cell wall teichoic acid production. Using quantitative (q)RT-PCR on the gene cadre putatively involved in cationic peptide resistance, we formulated a putative regulatory network compatible with microarray data sets, mainly implicating bacterial envelopes. Of interest, qRT-PCR of this same gene cadre from two distinct isogenic DAPS/DAPR clinical strain pairs revealed evidence of other strain-dependent networks operative in the DAPR phenotype. Comparative proteomics of 616 versus 701 revealed a differential abundance of proteins in various functional categories, including cell wall-associated targets and biofilm formation proteins. Phenotypically, strains 616 and 701 showed major differences in their ability to develop bacterial biofilms in the presence of the antibacterial lipid, oleic acid. Conclusions Compatible with previous in vitro observations, in vivo-acquired DAPR in S. aureus is a complex, multistep phenomenon involving: (i) strain-dependent phenotypes; (ii) transcriptome adaptation; and (iii) modification of the lipid and protein contents of cellular envelopes

There is ongoing controversy about the role of health-care workers in transmission of meticillin-resistant Staphylococcus aureus (MRSA). We did a search of the literature from January, 1980, to March, 2006, to determine the likelihood of MRSA colonisation and infection in health-care workers and to assess their role in MRSA transmission. In 127 investigations, the average MRSA carriage rate among 33 318 screened health-care workers was 4.6%; 5.1% had clinical infections. Risk factors included chronic skin diseases, poor hygiene practices, and having worked in countries with endemic MRSA. Both transiently and persistently colonised health-care workers were responsible for several MRSA clusters. Transmission from personnel to patients was likely in 63 (93%) of 68 studies that undertook genotyping. MRSA eradication was achieved in 449 (88%) of 510 health-care workers. Subclinical infections and colonisation of extranasal sites were associated with persistent carriage. We discuss advantages and disadvantages of screening and eradication policies for MRSA control and give recommendations for the management of colonised health-care workers in different settings.

OBJECTIVES: The aim of this study was to determine the temporal relation between the use of antibiotics and alcohol-based hand rubs (ABHRs) and the incidence of methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile. METHODS: An interventional time-series analysis was performed to evaluate the impact of two promotion campaigns on the consumption of ABHRs and to assess their effect on the incidence of non-duplicate clinical isolates of MRSA and C. difficile from February 2000 through September 2006. This analysis was combined with a transfer function model of aggregated data on antibiotic use. RESULTS: Consumption of ABHRs correlated with MRSA, but not with C. difficile. The final model demonstrated the immediate effect of the second hand hygiene promotion campaign and an additional temporal effect of fluoroquinolone (time lag, 1 month; i.e. antibiotic effect delayed for 1 month), macrolide (lag 1 and 4 months), broad-spectrum cephalosporins (lag 3, 4 and 5 months) and piperacillin/tazobactam (lag 3 months) use. The final model explained 57% of the MRSA variance over time. In contrast, the model for C. difficile showed only an effect for broad-spectrum cephalosporins (lag 1 month). CONCLUSIONS: We observed an aggregate-level relation between the monthly MRSA incidence and the use of different antibiotic classes and increased consumption of ABHR after a successful hand hygiene campaign, while no association with ABHR use was detected for C. difficile.

Background. Oral combination therapy with fluoroquinolones plus rifampicin is a promising alternative to standard parenteral therapy for staphylococcal infections. Methods. In a multicenter, randomized trial, we compared the efficacy, safety, and length of hospital stay for patients with staphylococcal infections treated either with an oral combination of a fluoroquinolone (fleroxacin) plus rifampicin or with standard parenteral treatment (flucloxacillin or vancomycin). Patients were included if cultures showed the presence of bacteremia or deep-seated infections with Staphylococcus aureus (104 patients) or catheter-related bacteremia due to drug-susceptible, coagulase-negative staphylococci (23 patients). Results. The cure rate in the intention-to-treat analysis was 78% for the fleroxacin-rifampicin group (68 patients) and 75% for the standard therapy group (59 patients; 47 received flucloxacillin, and 12 received vancomycin); in the population of clinically evaluable patients (n = 119), the cure rate was 82% and 80%, respectively; and in the population of microbiologically evaluable patients (n = 103), the cure rate was 86% and 84%, respectively. Clinical and bacteriological failures after S. aureus infections were documented in similar proportions of patients. The median length of hospital stay after study entry was 12 days in the fleroxacin-rifampicin group, compared with 23 days in the standard treatment group (P = .006). More adverse events probably related to the study drug were reported in the fleroxacin-rifampicin group than in the standard therapy group (15 of 68 vs. 5 of 59 patients; P = .05). Conclusions. This study suggests that an oral regimen containing a fluoroquinolone plus rifampicin may be effective for treating staphylococcal infections, allowing earlier discharge from the hospital