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Rapid Test to Detect Staphylococcus Aureus in Blood and Wound Infections

This study has been completed.
Baylor College of Medicine
Information provided by:
VA Medical Center, Houston Identifier:
First received: September 9, 2010
Last updated: NA
Last verified: October 2008
History: No changes posted
The purpose of this study is to determine whether the Cepheid GeneXpert system accurately detects Methicillin-Resistant and -Susceptible Staphylococcus aureus in blood cultures and wound swabs.

Staphylococcus Aureus
Staphylococcal Skin Infections

Study Type: Observational
Study Design: Time Perspective: Retrospective
Official Title: GeneXpert in Studying Staphylococcus Aureus Infections at the Michael E. DeBakey Medical Center, Houston, Texas

Resource links provided by NLM:

Further study details as provided by VA Medical Center, Houston:

Primary Outcome Measures:
  • concordance between PCR results and those of standard bacteriologic culture [ Time Frame: 1 year ]

Secondary Outcome Measures:
  • Impact of early identification of S. aureus on the antibiotics prescribed by physicians and subsequent clinical outcome. [ Time Frame: 1 year ]

Enrollment: 260
Study Start Date: April 2008
Study Completion Date: August 2010
Primary Completion Date: August 2009 (Final data collection date for primary outcome measure)
Detailed Description:

Staphylococcus aureus (SA) remains a major pathogen for human beings, causing infections of skin, soft tissue, bone, and other organs. Bacteremia due to this organism is common, and often occurs in association with medical interventions such as intravenous lines and implantable devices. With the increase in methicillin-resistant S. aureus (MRSA), there has been increasing dependence upon vancomycin, a drug that is inferior to the beta-lactams in its activity against methicillin-susceptible S. aureus (MSSA). If the microbiology laboratory had the ability to identify S. aureus (SA) and its drug susceptibility within hours rather than days, focused therapy would be possible earlier in the course of illness. Clinicians would be able to discontinue antibiotics when SA is not present, to discontinue other broad-spectrum antibiotics when SA is present, or to replace empiric vancomycin with nafcillin when MSSA is identified.

The GeneXpert system (Cepheid) uses real-time PCR to detect genes that encode Staphylococcus aureus protein A (SPA), the staphylococcal cassette chromosome (SCC) and methicillin resistance (mecA). All blood cultures with Gram stain revealing Gram positive cocci in clusters will be tested by PCR the day they became positive. Wound swabs submitted for routine bacteriologic culture will be tested within 48 hr of collection. Results will be compared with those of standard bacteriologic culture. In addition, discrepancies between the GeneXpert and wound culture results will be reviewed in the medical record to ascertain whether antibiotic use at the time of specimen collection is associated with false positive results in which the wound culture yields no S. aureus but PCR detects staphylococcal DNA components.

In the second phase of the study, PCR results for wound swabs and blood cultures will be reported to physicians immediately upon completion of the reaction. The clinical impact of early identification of S. aureus will be determined by comparing antibiotic treatment and clinical outcome of patients for whom early identification was available with those of patients for whom conventional bacteriological culture was the sole diagnostic test.


Ages Eligible for Study:   18 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Probability Sample
Study Population
The study population includes adult and geriatric patients at the Michael E. DeBakey VA Medical Center for have suspected blood and wound infections.

Inclusion Criteria:

  • Positive blood culture with Gram stain revealing Gram positive cocci in clusters
  • All wound swabs submitted to the microbiology lab for standard bacteriologic culture may be included.

Exclusion Criteria:

  • Blood cultures that became positive more than 24 hours previously
  • Wound swabs for which over 48 hours have passed from the time of collection
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT01198262

United States, Texas
Michael E. DeBakey VA Medical Center
Houston, Texas, United States, 77030
Sponsors and Collaborators
VA Medical Center, Houston
Baylor College of Medicine
Principal Investigator: Daniel M Musher, MD MEDVAMC
Study Chair: Mark Parta, MD MEDVAMC
  More Information

Responsible Party: Daniel M Musher, Michael E. DeBakey VA Medical Center Identifier: NCT01198262     History of Changes
Other Study ID Numbers: H-23059
Study First Received: September 9, 2010
Last Updated: September 9, 2010

Keywords provided by VA Medical Center, Houston:
polymerase chain reaction

Additional relevant MeSH terms:
Communicable Diseases
Skin Diseases, Infectious
Staphylococcal Skin Infections
Bacterial Infections
Systemic Inflammatory Response Syndrome
Pathologic Processes
Skin Diseases
Staphylococcal Infections
Gram-Positive Bacterial Infections
Skin Diseases, Bacterial processed this record on April 25, 2017