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Vancomycin-Resistant Staphylococcus aureus

April 16, 2014

Vancomycin-Resistant Staphylococcus aureus

  1. Larry M. Baddour, MD

The vanA gene was acquired by a CA-MRSA strain that caused bloodstream infection.

After emerging in the 1990s, community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) spread rapidly across the U.S. Fortunately, most infections caused by these organisms have been skin abscesses with low risk for serious complications. In 2002, the vanA gene cluster, which confers vancomycin resistance, was described in MRSA. Despite fears that vancomycin-resistant MRSA (VRSA) strains would become common, only 13 VRSA isolates have been reported in the U.S. — all from patients with skin or soft-tissue infections. Multilocus sequence typing has shown that 12 of them belong to clonal complex 5, which is hospital-associated.

Now, investigators have described a patient in Brazil who underwent multiple courses of antibiotic therapy, including glycopeptides, for a serious skin condition. He developed a bloodstream infection caused by a CA-MRSA strain that was initially vancomycin susceptible but acquired the vanA gene cluster during antibiotic therapy

Several molecular and genetic techniques were used to characterize the patient's isolates.

Based on multilocus sequence typing, the patient's vancomycin-resistant strain was closely related to CA-MRSA USA300-ST8 strains that have SCCmec type IVa and are now found in several regions worldwide. The strain differed from the usual USA300 strains (including one reported from the northern part of South America) in that it lacked the genes encoding Panton–Valentine leukocidin. A conjugative plasmid, pBRZ01, carried the vanA cluster and could be readily transferred to other S. aureus strains.

Comment

Although just a case report, this paper deserves coverage because it demonstrates that a community-associated methicillin-resistant S. aureus strain that developed vancomycin resistance can cause serious invasive infection. Dissemination of this or other, similar strains could have major public health implications on a global scale.

  • Disclosures for Larry M. Baddour, MD at time of publication Editorial boards UpToDate Leadership positions in professional societies American Heart Association (Chairman, Rheumatic Fever, Endocarditis, Kawasaki Disease Committee)

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Reader Comments (3)

mostafayossef Physician, Pulmonary Medicine, saudi arabia

gd management

sandeeep Resident, Internal Medicine, india

Aspirin in lactation.what effects will come

Maxwell Hopp MBBCh,DCH,FCP,FRACP Physician, Pediatrics/Adolescent Medicine, Griffith Base Hoptal, NSW, Australia

Does Vancomycin resistance mean that the CA MRSA loses sensitivity to Clindamycin and Cotrimoxazole as well?

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