Karen Eichelberger

Carriage of Methicillin-Resistant Staphylococcus Aureus at Hospital Admission

OBJECTIVES To measure the prevalence of, and to establish predictors for, the nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) at hospital admission. To evaluate mannitol-salt agar with oxacillin for the simultaneous detection and identification of MRSA from nasal swabs. DESIGN Three-month prospective case-control survey, with data collected from interviews and computerized databases. The criterion standard for MRSA detection was culture on Mueller-Hinton agar with oxacillin 6 microg/mL (National Committee for Clinical Laboratory Standards method). SETTING 320-bed tertiary-care hospital. PATIENTS 387 patients screened within 24 hours after admission, including 10 MRSA carriers (cases), 291 patients with no S aureus, and 86 patients with methicillin-susceptible S aureus. RESULTS The prevalence of MRSA nasal carriage was 2.6%, whereas the prevalence of carriage was 3.1% when both nasal and wound cultures were performed. The significant predictors of carriage were a prior detection of MRSA, open wounds, diabetes mellitus, treatments by injection, prior nursing home stays, visits at home by a nurse, and prior antibiotic treatments. Cases had stayed for longer periods in hospitals and had received longer antibiotic treatments within a year. Eighty patients (including the 10 cases) had diabetes, had been exposed to healthcare facilities within a year, and had antibiotics within 6 months. The sensitivity and negative predictive value of nasal swabs on mannitol-salt agar with oxacillin were 60% and 71%, respectively. CONCLUSION MRSA carriage on admission to the hospital may be an increasing and underestimated problem. Further studies are needed to develop and validate a sensitive and specific prediction rule.

Rapid Identification of Staphylococcus aureus in Blood Cultures by Use of the Direct Tube Coagulase Test

ABSTRACT Direct tube coagulase testing for identification of Staphylococcus aureus from BACTEC culture broth showed a sensitivity, a specificity, and positive and negative predicative values of 34%, 100%, 100%, and 80.2% with 2 h of incubation and 65%, 98.7, 99.7%, and 88.6% with 4 h of incubation. Anaerobic blood culture contributed significantly to the detection of S. aureus.

Effective Use of PCR for the Detection of Cytomegalovirus Viremia and Monitoring Therapy in Immunocompromised Patients

Objective: To establish criteria for the most productive use of quantitative cytomegalovirus (CMV) polymerase chain reaction (PCR) in transplant and HIV patients, both for diagnosis and monitoring infections. Method: We evaluated the medical records of 108 HIV, bone marrow transplant (BMT), and solid organ transplant (SOT) patients who had positive CMV viral load tests. Results: Cytomegalovirus was detected at median of 47 and 183.5 days after BMT and SOT, respectively. All HIV patients who had positive CMV viremia had CD4 cell counts <175 cells/μL, and all HIV patients with endorgan disease had CD4 cell counts <75 cells/ μL. The median time for CMV to become undetectable after treatment was 22, 21, and 31 days for HIV, BMT, and SOT patients, respectively. Conclusion: Cytomegalovirus viral load screening focusing on high-risk periods may be cost effective. A CMV viral load does not decrease rapidly with treatment. The CMV PCR for monitoring therapy should not be performed more than once a week.

Limited Utility of Bone Marrow Culture: A Ten-Year Retrospective Analysis

Background A retrospective examination of the utility of bone marrow sampling for identification of microorganisms was performed in an urban tertiary care hospital. Methods A retrospective review of culture and histology data from bone marrow specimens was performed for a 10-year period. Results Neither bone marrow culture nor special stains for microorganisms provided incremental benefit in identifying microbial agents compared with other methods such as blood culture. Conclusion Bone marrow aspiration/biopsy should only be performed selectively for diagnosis of an infectious etiology.

Rapid Identification of Staphylococcus aureus Directly from Bactec Blood Culture Broth by the BinaxNOW S. aureus Test

ABSTRACT The BinaxNOW Staphylococcus aureus testing showed sensitivity, specificity, and positive and negative predicative values of 97.6%, 100%, 100%, and 98.4%, respectively, for identification of S. aureus from Bactec blood culture broth. Importantly, the test performed equally well on aerobic and anaerobic culture broth.