We performed a prospective study of all patients with bacteremic pneumonia due to Staphylococcus aureus over a period of 6 years during an outbreak of methicillin-resistant S. aureus (MRSA). Patients with bacteremic pneumonia due to MRSA (32 cases) or methicillin-susceptible S. aureus (MSSA; 54 cases) were compared. The patients with MRSA pneumonia were older and were more likely than those with MSSA pneumonia to have predisposing factors for acquisition of the infection. There were no differences in clinical findings, radiological pattern, or complications in clinical evolution among patients with MRSA and MSSA pneumonia. Mortality was significantly higher among MSSA-infected patients treated with vancomycin than among those treated with cloxacillin (47% vs. none; P<.01). Multivariate analysis (stepwise logistic regression method) showed a relationship between mortality and the following variables: septic shock (odds ratio [OR], 61), vancomycin treatment (OR, 14), and respiratory distress (OR, 8).

We prospectively studied all cases of Staphylococcus aureus bacteremia that occurred during an extensive outbreak of methicillin-resistant S. aureus (MRSA) in our hospital over a 4-year period (January 1990 through September 1993). We report the results of a comparative analysis of the clinical characteristics and mortality rates among patients with nosocomial bacteremia caused by MRSA (84 cases) or methicillin-susceptible S. aureus (MSSA; 100 cases). The patients with MRSA bacteremia were older than those with MSSA bacteremia (69 years vs. 54 years, respectively; P < .01) and were more likely than those with MSSA bacteremia to have the following predisposing factors: a prolonged hospitalization (32 days vs. 14 days, respectively; P < .01); prior antimicrobial therapy (61% vs. 34%, respectively; P < .01); urinary catheterization (58% vs. 27%, respectively; P < .01); nasogastric tube placement (31% vs. 13%, respectively; P < .01); and prior surgery (45% vs. 31%, respectively; P = .05). Multivariate analysis with use of the stepwise logistic regression method showed a relationship between mortality and the following variables: methicillin resistance (odds ratio [OR], 3), meningitis (OR, 13), and inadequate treatment (OR, 11).

We report the presence of the cfr gene underlying the resistance mechanism involved in a clinical outbreak of linezolid-resistant S. aureus.

Staphylococcal resistance to linezolid (LZD) is mediated through ribosomal mutations (23S

In hospital outbreaks of methicillin-resistant Staphylococcus aureus (MRSA) many patients are initially colonized without infection. The reasons why some progress to infection while others do not are not known. A cohort of 479 hospital patients, initially only colonized with MRSA, was followed prospectively for the development of MRSA infection. Risk factors for progression to infection were assessed using Cox proportional hazards survival analysis. Fifty-three patients (11 .l%) developed 68 MRSA infections. Intensive care setting, administration of three or more antibiotics, ulcers, surgical wounds, nasogastric or endotracheal tubes, drains, and urinary or intravenous catheterization were all associated with increased rates of MRSA infection. Multivariate analysis showed that intensive care patients, compared with medical natients. had a higher rate of develoning MRSA infection within the first' four days of admission, with a hazard ra;o of 26.9 (95% CI 5.7-126). Surgical wounds, pressure ulcers and intravenous catheterization were also independent risk factors, with hazard ratios (and 95% CI) of 2.9 (1.3-6.3), 3.0 (1.6-5.7) and 4.7 (l+15.6), respectively. These findings suggest that, during an MRSA outbreak, clinical infection would be reduced if surgical and intensive care patients received priority for the prevention of initial colonization with MRSA. Prevention of pressure ulcers, and strict aseptic care of intravenous catheters and surgical wounds would also reduce the development of MRSA infection. Since early treatment with vancomycin is known to reduce the mortality, patients colonized with MRSA who also have one or more of these risk factors may warrant empirical vancomycin therapy at the earliest suggestion of infection.

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The results show that a subset of patients with RRMS experience HHV-6 active infection, and there likely is an association between the viral active replication and relapses; therefore, HHV-6 active infection may imply a greater risk of exacerbations in a subgroup of patients with RRMS.

The aim of this study was to determine the susceptibility patterns of 100 group B streptococcal strains isolated in our hospital and to ascertain tolerance to penicillin by determining quantitative killing curves. We found two strains with intermediate susceptibility to penicillin and eight strains to ampicillin. Seventeen isolates were tolerant to penicillin, with bacterial counts decreasing 2 to 3 log during the first 8 h but still above 10(2) CFU/ml after 24 h. The kinetic study shows that penicillin tolerance is not rare among group B streptococci isolated in our hospital.