NEW YORK (Reuters Health) - Vancomycin-resistant Staphylococcus aureus has been isolated from a patient without recent exposure to vancomycin, according to a report in the April 15th issue of Clinical Infectious Diseases.
This is the second clinical S. aureus isolate with high-level vancomycin resistance and the first in a patient without significant exposure to vancomycin, the authors explain.
Dr. Cynthia J. Whitener from The Penn State Milton S. Hershey Medical Center, Hershey, Pennsylvania and colleagues report findings from their investigation of the world’s second clinical isolate of vancomycin-resistant S. aureus (VRSA) in an obese elderly man hospitalized with an infected chronic heel ulcer and osteomyelitis. Methicillin-resistant S. aureus (MRSA) and vancomycin-resistant enterococci (VRE) had previously been isolated from the patient’s ulcer.
The VRSA isolate contained the mecA (mediating oxacillin resistance) and the vanA (mediating vancomycin resistance) genes, the report indicates, but the isolate was susceptible to several other antimicrobial agents.
None of the patient’s contacts carried VRSA or VRE, the authors report, but 15% of the patient’s contacts (including his daughter) carried MRSA.
Follow-up surveillance cultures did not reveal any MRSA, VRSA, or VRE, the results indicate, and cultures obtained at the time of a later operative debridement of the calcaneus and surrounding soft tissue grew no VRSA, MRSA, or VRE.
“The persistent presence of [MRSA and VRE] in this patient’s ulcer and the documentation of the vanA gene in this VRSA suggest the possibility that the VRSA acquired vancomycin resistance via horizontal transfer of the vanA gene from a VRE,” the investigators speculate. “The events that trigger in vivo transfer of the vanA gene from VRE to MRSA need further study.”
“The patient in our investigation did not receive vancomycin during the 5 years preceding this infection,” the authors note. “Therefore, concurrent or recent vancomycin exposure is not a prerequisite for the development of VRSA.”
“Instead,” the investigators write, “we conclude that frequent use of other antimicrobial agents provided sufficient selective pressure to promote colonization and/or infection with VRE and MRSA, eventually resulting in the emergence of VRSA.”
“This observation once again argues for judicious use of antibiotics to minimize the threat of VRSA selection in patients at risk,” writes Dr. Karen Bush from Johnson & Johnson Pharmaceutical Research & Development, Raritan, New Jersey in a related editorial.
“We should proceed with caution, but, thus far, VRSA has been manageable when detected,” Dr. Bush adds. “Our major challenge in the future may not be treatment and dissemination of VRSA itself but, rather, the accurate detection of VRSA when it appears.”
Source: Clin Infect Dis 2004;38:1049-1057. [ Google search on this article ]
MeSH Headings:Behavioral Sciences: Biological Phenomena: Biological Phenomena, Cell Phenomena, and Immunity: Biological Sciences: Biology: Data Collection: Demography: Behavioral Disciplines and Activities: Drug Resistance, Microbial: Environment and Public Health: Epidemiologic Methods: Genetics: Genetics, Microbial: Health: Health Occupations: Health Services Administration: Information Science: Medicine: Microbiologic Phenomena: Investigative Techniques: Morbidity: Pharmacogenetics: Population Characteristics: Preventive Medicine: Public Health: Quality of Health Care: Social Sciences: Specialties, Medical: Vital Statistics: Epidemiologic Measurements: Incidence: Health Care Quality, Access, and Evaluation: Health Care Evaluation Mechanisms: Vancomycin Resistance: Analytical, Diagnostic and Therapeutic Techniques and Equipment: Anthropology, Education, Sociology and Social Phenomena: Biological Sciences: Health Care: Information Science: Psychiatry and PsychologyCopyright © 2002 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.
