title: Rapid MRSA PCR on respiratory specimens from ventilated patients with suspected pneumonia: a tool to facilitate antimicrobial stewardship.
abstract: Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of pneumonia in ventilated patients. Our objective was to evaluate the GeneXpert MRSA/SA SSTI Assay (Xpert MRSA/SA) (Cepheid, Sunnyvale, CA) for use in lower respiratory tract (LRT) specimens for rapid MRSA detection and to determine the potentially saved antibiotic-days if a culture-based identification method was replaced by this assay. Remnant LRT samples from ventilated patients submitted to the microbiology laboratory for routine culture were tested using conventional culture and Xpert MRSA/SA. One hundred of 310 LRT specimens met the inclusion criteria. Ten samples were positive for MRSA by Xpert MRSA/SA, while six were positive by routine culture methods. Xpert MRSA/SA correctly identified 5/6 positive and 89/94 negative MRSA specimens, for a sensitivity of 83.3%, specificity of 94.7%, positive predictive value of 45.6%, and negative predictive value of 98.9%. The assay also correctly detected 3/3 positive and 90/97 negative methicillin-susceptible S. aureus (MSSA) specimens, for a sensitivity of 100%, specificity of 92.8%, positive predictive value of 30%, and negative predictive value of 100%. A total of 748 vancomycin and 305 linezolid antibiotic-days were associated with the enrolled specimens. Vancomycin and linezolid utilization could decrease by 68.4% and 83%, respectively, if discontinued 1 day after negative polymerase chain reaction (PCR) results. The Xpert MRSA/SA SSTI rapid MRSA PCR assay performed well in respiratory samples from ventilated patients with suspected pneumonia and has the potential to facilitate stewardship efforts such as reducing empiric vancomycin and linezolid therapy.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO, USA.|Department of Medicine, Division of Pulmonary and Critical Care, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: S E
authors.initials: SE
authors.lastname: Trevino
authors.affiliation: Department of Pathology & Immunology, Division of Laboratory and Genomic Medicine, Washington University School of Medicine, 660 S. Euclid Ave., Campus Box 8118, St. Louis, MO, 63110, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Pence
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO, USA.|Department of Infectious Diseases, Bern University Hospital, University of Bern, Bern, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Marschall
authors.affiliation: Department of Medicine, Division of Pulmonary and Critical Care, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: M H
authors.initials: MH
authors.lastname: Kollef
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: H M
authors.initials: HM
authors.lastname: Babcock
authors.affiliation: Department of Pathology & Immunology, Division of Laboratory and Genomic Medicine, Washington University School of Medicine, 660 S. Euclid Ave., Campus Box 8118, St. Louis, MO, 63110, USA. cburnham@wustl.edu.
authors.forename: C-A D
authors.initials: CD
authors.lastname: Burnham
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D004363:Drug Utilization / Q000592:standards; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification*; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D053717:Pneumonia, Ventilator-Associated / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology; D016133:Polymerase Chain Reaction / Q000379:methods*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013203:Staphylococcal Infections / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology; D013997:Time Factors; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents