Risk Factors for Persistent Carriage of Methicillin-Resistant Staphylococcus aureus

We determined risk factors associated with persistent carriage of methicillin-resistant Staphylococcus aureus (MRSA) among 102 patients enrolled in a double-blind, placebo-controlled trial of nasally administered mupirocin ointment. MRSA decolonization was unsuccessful in 77 (79%) of 98 patients who met the criteria for evaluation. By univariate analysis, 4 variables were found to be associated with persistent MRSA colonization (P < .1 for all 4): absence of mupirocin treatment, previous fluoroquinolone therapy, ⩾2 MRSA-positive body sites, and low-level mupirocin resistance. After multivariable Cox proportional hazards modeling, the presence of ⩾2 positive body sites (adjusted hazard ratio [AHR], 1.7; 95% confidence interval [CI], 1.0-2.9) and previous receipt of a fluoroquinolone (AHR, 1.8; 95% CI, 1.0-3.3) were independently associated with MRSA persistence, whereas nasal mupirocin tended to confer protection (AHR, 0.6; 95% CI, 0.4-1.0). Low-level mupirocin resistance was observed in 9 genotypically different MRSA strains and was not independently associated with chronic MRSA carriage (AHR, 1.5; 95% CI, 0.9-2.5). Our findings suggest that multisite MRSA carriage and previous receipt of a fluoroquinolone are independent risk factors for persistent MRSA colonizatio

Resistance to amikacin and gentamicin among Gram-negative bloodstream isolates in a university hospital between 1989 and 1994

ObjectiveTo characterize antimicrobial resistance patterns to amikacin (AN) and gentamicin (GM) among Gramnegative bloodstream isolates and to determine the possible relationship between use of AN and GM and the occurrence of antibiotic resistance during a 6-year period.MethodsStandard media and techniques of isolation and identification were used. Antimicrobial susceptibility testing was performed with the disk diffusion method and API rapid ATE E strips. Data on consumption of aminoglycosides were collected by the central hospital pharmacy and were expressed as daily defined doses.ResultsOne thousand nine hundred and four bloodstream isolates were tested for AN and GM susceptibility between 1989 and 1994. Activities of AN and GM remained high during the study period against most isolates of Gram-negative bacteria. No relationship could be observed between the use of AN/GM and the rate of AN/GM resistance. Nosocomial Gram-negative No relationship could be bloodstream isolates showed a higher degree of resistance towards both AN (3.9% of all nosocomial iveisolates) and GM (7.9%) than community-acquired isolates (1.8% toward AN and 3.1% towards GM, respectively). There was a significant increase (7.9%)than(P= 0.004) in the risk of GM resistance in patients with nosocomial Gram-negative bacteremia detected more than 14 days after admission. The proportion of GM-susceptible Pseudornonas aeruginosa isolates detected decreased linearly from 97% for infections acquired between day 3 and day 10 following admission to 80% for bacteremia developing 30 days or more after admission (P= 0.008).ConclusionsAN and GM remain highly active antimicrobial drugs for treatment of GNB in times of growing resistance to cephalosporins and fluoroquinolones

Early Termination of a Prospective, Randomized Trial Comparing Teicoplanin and Flucloxacillin for Treating Severe Staphylococcal Infections

In a prospective, randomized trial, teicoplanin (at a 400-mg intravenous loading dose followed by 200 mg/day intravenously or intramuscularly) was compared with flucloxacillin (8 g/day) in patients with severe staphylococcal infections. Teicoplanin proved unsatisfactory for the following reasons: (1) failures or relapses were more frequent in the teicoplanin group, and (2) blood levels were difficult to predict and tended to be low 24 hr after the loading dose. Future trials with this agent should use much-higher dose

Group A β-Hemolytic Streptococcus Meningitis: Clinical and Microbiological Features of Nine Cases

Group A β-hemolytic streptococcus (GAS) meningitis is a rare disease in adults. We conducted a retrospective study to describe clinical and microbiological features of nine cases of GAS meningitis in Switzerland. Of nine patients, six had neurosurgical conditions, and five had upper respiratory tract infections. Eight cases were community-acquired. The outcome of GAS meningitis was favorable; only one patient died of neurosurgical complications. No patient presented with toxic shock syndrome. Serotyping failed to reveal a dominant strain, and genotyping revealed that two strains carried the gene encoding the streptococcal pyrogenic exotoxin C and that one strain carried the gene encoding the streptococcal pyrogenic exotoxin A. Our observations suggest that GAS meningitis in adults is associated with neurosurgical conditions and/or an upper respiratory tract infectio

Resistance of Staphylococcus aureus Recovered from Infected Foreign Body In Vivo to Killing by Antimicrobials

Because persistence of infections associated with prosthetic material despite the use of appropriate antibioticsis a major clinical problem,the antimicrobial susceptibility of bacteria responsible for a chronic subcutaneous tissue cage infection in rat was investigated ex vivo. Three to 6 weeks after the initiation of infection, suspensions of two strains of Staphylococcus aureus recovered from the foreign body surface and surrounding fluid wereexposed to either oxacillin, vancomycin, fleroxacin, gentamicin, or rifampin. The MBCs of these bacteria were markedly elevated, in most cases 128 to >256 times higher than the MBCof batch culture S. aureus in either logarithmic or stationary phase. Kinetic studies showed the bacteria did not growwhen incubated for 2 h in Mueller-Hinton broth, possibly reflecting dormancy. Their killing wasslow and incompleteby all antibioticsat > 8 times their MIC. These data provide direct evidence of a decreased susceptibility of S. aureus to the killing effect of antimicrobials during chronic foreign body infections in viv

Automatic Alerts for Methicillin-Resistant Staphylococcus aureus Surveillance and Control: Role of a Hospital Information System

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is an escalating problem in hospitals worldwide. The hospital reservoir for MRSA includes recognized and unrecognized colonized or infected patients, as well as previously colonized or infected patients readmitted to the hospital. Early and appropriate infection control measures (ICM) are key elements to reduce MRSA transmission and to control the hospital reservoir. Objective: To describe the role of an expert system applied to the control of MRSA at a large medical center (1,600 beds) with high endemic rates. Methods: The University Hospital of Geneva has an extended hospital information system (HIS), DIOGENE, structured with an open distributed architecture. It includes administrative, medical, nursing, and laboratory applications with their relational databases. Among available patient databases, clinical microbiology laboratory and admission-discharge-transfer (ADT) databases are used to generate computer alerts. A laboratory alert (lab alert) is printed daily in the Infection Control Program (ICP) offices, listing all patients with cultures positive for MRSA detected within the preceding 24 hours. Patients might be either newly detected patients colonized or infected with MRSA, or previously recognized MRSA patients having surveillance cultures. The ICP nurses subsequently go to the ward or call the ward personnel to implement ICM. A second alert, the "readmission alert,” detects readmission to the hospital of any patient previously colonized or infected with MRSA by periodic queries (q 1 min) to the ADT database. The readmission alert is printed in the ICP offices, but also forwarded with added guidelines to the emergency room. Results: During the first 12 months of application (July 1994 to June 1995), the lab alert detected an average of 4.6 isolates per day, corresponding to 314 hospital admissions (248 patients); the use of this alert saved time for the ICP nurses by improving work organization. There were 438 readmission alerts (1.2 alerts per day) over the study period; of 347 patients screened immediately upon readmission, 114 (33%) were positive for MRSA carriage. Delayed recognition of readmitted MRSA carriers decreased significantly after the implementation of this alert; the proportion of MRSA patients recognized at the time of admission to the hospital increased from 13% in 1993 to 40% in 1995 (P<.001). Conclusions: Hospital information system-based alerts can play an important role in the surveillance and early prevention of MRSA transmission, and it can help to recognize patterns of colonization and transmissio

Fibronectin, Fibrinogen, and Laminin Act as Mediators of Adherence of Clinical Staphylococcal Isolates to Foreign Material

Bacterial adherence to polymer surfaces is a required early step in intravenous (iv) device infection. We collected eight strains of Staphylococcus aureus and 19 of coagulase-negative staphylococci from patients with proven iv device bacteremia and studied the role of plasma or connective-tissue proteins in promoting bacterial adherence to polymethylmethacrylate (PMMA) coverslips. Although only a negligible percentage of organisms adhered to albumin-coated PMMA, surface-bound fibronectin significantly promoted adherence of all isolates. Fibrinogen markedly promoted adherence of all S. aureus strains but of only four coagulase-negative strains. Thus, coagulase-negative staphylococci revealed a marked heterogeneity in adherence to fibrinogen-coated surfaces, a result suggesting the existence of heretofore unknown receptors for fibrinogen. Laminin promoted adherence of staphylococci to a much lower extent. Although strain specific, adherence of clinical staphylococcal isolates to foreign surfaces is significantly increased by fibronectin, fibrinogen, and laminin, an observation suggesting the possible contribution of these proteins to the pathogenesis of iv device infectio