Why Did CA-MRSA Cross the Atlantic? To Get the Other Side!
Abstract & Commentary
By Carol A. Kemper, MD, FACP, Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases, Santa Clara Valley Medical Center and Camino Medical Group, Section Editor, Updates, Section Editor, HIV, is Associate Editor for Infectious Disease Alert
Dr. Kemper serves on the speaker’s bureau of ViroLogic, GlaxoSmithKline, Pfizer, Sanofi-Aventis, and Agouron, and does research for Abbott and ViroLogic.
Synopsis: Outbreaks of CA-MRSA are occurring with increasing frequency and the indications for an approach to decolonization of patients and healthcare workers is discussed here.
Source: Tietz A, et al. Transatlantic Spread of the USA300 Clone of MRSA. N Engl J Med. 2005;353:532-533.
Surveillance indicates that community-associated MRSA (CA-MRSA) strains are beginning to appear with increasing frequency in certain parts of Europe. I was, therefore, surprised to read that a healthy 41-year-old Swiss physician, who had just returned to Switzerland following a 3-year fellowship in the United States, was prohibited from returning to patient care until he was decolonized of MRSA. He had been screened in the United States about 3 months before returning to Switzerland, with negative nares swab cultures, which the Swiss presumed was from exposure in the United States. Swiss protocol requires verification of negative cultures in individuals returning from areas of high prevalence for MRSA, and repeat cultures grew MRSA. The isolate was identified as USA300 by pulse field gel electrophoresis, and carried SCCmecIV and encoded for Panton-Valentine leukocidin.
The physician was treated with antiseptic body scrubs with 4% chlorhexidine, mupirocin, 2% ointment to his nares, and 2% chlorhexidine oropharyngeal rinses for 5 days. Subsequent cultures were negative, and he was allowed to return to practice. Tietz and colleagues did not illuminate what would have occurred should this regimen have failed.
Commentary
Outbreaks of CA-MRSA are occurring with increasing frequency in number of major urban centers within the United States. In our county, located in the southern-most pocket of the San Francisco Bay Area, outbreaks have been reported among professional athletes, high school athletic teams, day care settings, among men who have sex with men, and at the county jail, where CA-MRSA has become endemic. Data collected from our local laboratories and hospitals indicates that the percentage of S. aureus that is MRSA now approaches or exceeds 50%. Thus far this year, at the county hospital and in the jails, upwards of 70% of all S. aureus isolated is MRSA. As many of you know, these community strains of MRSA are genetically distinct from earlier hospital strains, and have predilection for causing folliculitis, furunculosis, and soft tissue abscesses and necrosis.
There are, thus far, no formal clinical guidelines in the United States for attempted treatment to eradicate (decolonize) persons persistently colonized with MRSA and, in particular, there are no guidelines on the management of hospital personnel infected or colonized with MRSA. Even after successful treatment of an active infection, patients may remain colonized with residual MRSA organisms on their nares, mucous membranes, and on the surface of their skin. Treatment with a single orally administered antibiotic agent, such as trimethoprimsulfamethoxazole or ciprofloxacin, has a limited chance of eradicating MRSA from skin and mucous membranes. Treatment with vancomycin, which penetrates poorly into endothelium and mucous membranes, is probably less effective. Even if MRSA is eradicated, patients may become recolonized. Available data suggest that about 25% of family members of individuals infected or colonized with MRSA may also be colonized. Family pets, such as dogs and horses, may also be colonized in their nares, and outbreaks of MRSA within families, riding facilities, and at veterinary facilities with animal-to-human transmission, and vice versa, is well-described.
For these reasons, decolonization has not been generally recommended in the United States unless infections recur, multiple infections recur within the same family or group, or if an individual is at higher risk for serious infection (eg, diabetes, anticipating surgery, those with immune suppression). At our hospital,we have been informally attempting to decolonize medical personnel on an as needed basis, although physicians have not been prohibited from working should they show evidence of nasal colonization.
While an optimal method for eradication of colonization has not been established, a number of different methods have been suggested with varying success. Most of these include the use of one or 2 orally administered antibiotics, depending on the susceptibility profile of the isolate, with or without the addition of nasal decolonization with intranasal mupirocin BID to TID for 5-10 days. Skin antiseptics (eg, Hibiclens, chlorhexidine baths) have also been used in addition to the above regimens. The Europeans employed the use of an orophryngeal antiseptic, which may be reasonable in some cases, although the percent solution used by the Swiss is significantly higher than that approved for use in the United States (Peridex, Zila, Periogard, and Colgate are FDA approved and contain 0.12% chlorhexidine.
For those interested parties, and with no randomized controlled data to support its use, this is the protocol that I have (lately) been using in select patients and occasionally in medical personnel:
-First, culture the patients’ nares and any previously infected site, as is reasonable, to establish sites of persistent colonization. If a gay man (man who has sex with men), consider culturing the rectal area.
-Depending on the organism’s susceptibility profile, prescribe a combination of ciprofloxacin 500 mg BID plus rifampin 600 mg daily; trimethoprim-sulfa-methoxazole DS BID plus rifampin 600 mg daily; or linezolid 600 mg BID for 7-10 days (dose adjust both the ciprofloxacin and the TMP-SMX for estimated creatinine clearance < 50 mL/min, especially in an elderly person);
-For those patients with nares colonization, prescribe mupirocin 2% ointment for use in both nostrils 3 times daily for 7-10 days;
-Have the patient remove any piercings or jewelry causing local irritation for the duration of antibiotic therapy;
-Have the patient remove all acrylic nails or silk wraps;
-Have the patient shower daily with Dial or another good anti-bacterial soap;
-Have the patient scrub under the nails of their hands with a good nail brush and soap;
-Have the patient shower every other day with chlorhexidine 4% or Hibiclens 3 to 4 times over the next week;
-Have the patient wash all towels, linens, and frequently worn articles of clothing with hot water and laundry detergent;
-Have the patient clean and then disinfect with a product like bleach or Lysol to kill germs that may still be present, such as in bathrooms and sink areas;
-Advise the patient to use alcohol-based hand gels in bathroom and kitchen sink areas;
-If you wish to determine if the patient has been successfully cleared, recommend waiting at least 4 days after completing these steps before obtaining follow-up swab cultures. Some institutions may require 2 sets of negative screening cultures obtained at least 24 hours apart.
Patients with indwelling lines, catheters, tracheostomies, G-tubes, etc. are not good candidates for decolonization, as you are not likely to eradicate organisms from these surfaces.
Surveillance indicates that community-associated MRSA (CA-MRSA) strains are beginning to appear with increasing frequency in certain parts of Europe.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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