Are Bleach Baths Or Chlorhexidine Plus Mupirocin Ointment Useful To Decolonize Patients With Recurrent Methicillin Resistant Staphylococcus Aureus Infections? What Topical Recommendations Are Useful For Patients With Recurrent Infections?
Emily A.
Thorell,
MD
Recurrent community-associated MRSA (CA-MRSA) infections have become a tre- mendous burden for practitioners, patients, and their families. Many experts recommend decolonization protocols for patients with recurrent MRSA skin and soft tissue infections (SSTIs) as an attempt to decrease this burden. It is unclear from the literature whether decolonization with bleach or chlorhexidine plus or minus mupirocin ointment to colonized areas really works for recurrent MRSA. In addition, the optimal strategy to reduce or eradicate MRSA and prevent recurrence in healthy children is unknown. The body of evidence is expanding but not definitive. Basic hygiene measures should always be used whether or not decolonization is attempted. These measures are expanded upon in Questions 7 and 8. It is also unclear how often these strategies should be employed if in fact they work at all. Let’s look at the literature.
Recently, a randomized, investigator-blinded, placebo-controlled study looked at 31 patients with moderate-to-severe atopic dermatitis (eczema) with clinical signs of sec- ondary bacterial infection. They were randomized to receive either nasal mupirocin and bleach baths (treatment) or nasal petrolatum and plain water baths (placebo) for 3 months. Interestingly, the study found that patients with eczema were less frequently colonized with MRSA than other pediatric patients in this hospital. Although 87% of the patients with eczema were colonized with SA from skin lesions, only 7.4% were noted to be MRSA; and although 80% were colonized with SA in their nares, MRSA accounted for only 4%. During that time frame, MRSA was noted in 75% to 85% of SA cultures within the general population of this children’s hospital. The good news was that the patients who were treated did have reduced severity of their atopic dermatitis. From this study, we can conclude that using mupi- rocin nasally along with bleach baths will help eczema patients who are infected with SA.
Another study looked at whether hypochlorite (bleach) actually kills MRSA to determine the optimal concentration and duration. It was determined that a concentration of 2.5 µL/ mL dilution of bleach reduced the concentration of MRSA by 3 logs. Although higher doses achieved greater reduction in bacteria, the authors chose this dose as clinical experience suggested it was well tolerated by children. The authors then took this same concentration and measured the killing of bacteria over time. This showed that there was a 3 log decrease in the bacteria at 5 minutes, but a greater than 4 log decrease over 15 minutes (Figure 6-1). The 2.5-µL/mL dilution is equivalent to ½ cup (120 mL) of bleach in one-quarter filled stan- dard tub (about 13 gallons). This is an in vitro study; therefore, it does not directly translate into decreasing the recurrence rate of MRSA SSTI. This concentration of bleach used on the skin of infected or colonized patients may help to decrease colonization and perhaps decrease recurrence, but this still needs further study in a clinical trial.
Figure 6-1. (A) Dose–response killing of control S aureus with increasing concentrations of hypo- chlorite incubated for 10 minutes at 37°C Mean colony counts (CFU) of remaining live bacteria on logarithmic scale (n 4, SD). (B) Time course for the response of control S aureus for increasing incubation times, 2.5 µL/mL hypochlorite solutions incubated at 37°C Average colony counts of remaining live bacteria on logarithmic scale (n 5, SD). (Reproduced with permission from Pediatric Inf Dis, Vol. 27, Page 934, Copyright © 2008 by the WK.)
Chlorhexidine washes are also recommended by many experts. These are generally preferred by adults and older children who would rather use a shower than a bath. Most of the literature examining chlorhexidine is for both infection control in hospitals and prevention of catheter-associated and surgical site infections in both adults and children. For infection prevention purposes, chlorhexidine is becoming the preferred agent for sterile dressing changes and many surgical scrubs. Data as to whether this is also a good agent to address recurrent CA-MRSA SSTI are not available.
Mupirocin alone may be effective in reducing MRSA colonization, but it has not been shown to be sustained or to prevent recurrent infections among carriers. Reviews have shown that it may be useful in decreasing colonization in surgical and dialysis patients and reducing nosocomial infections in this population, but does not benefit nonsurgical patients. It has been used in adjunct to bleach or chlorhexidine by many experts. Using it in the nares alone may not be adequate as some patients are colonized in multiple or other areas. Conversely, the use of chlorhexidine wipes alone without nasal mupirocin does not appear to be effective.
Does the site of colonization matter? Approximately 25% to 30% of people are carriers of SA. In children, MRSA colonization rates have been reported anywhere from 0% to 22% depending on the location. Most of the focus of decolonization protocols has histori- cally been the anterior nares, but other sites may be more likely to carry the bacteria. Sites of carriage include the anterior nares, perirectal area or perineum, and skin in general. Medical instrumentation such as tympanostomy tubes, gastrostomy tubes, tracheostomy tubes, and central lines can also be colonized. Another interesting study cultured the nares and rectum of 60 children with SA skin or soft tissue infection as well as 90 chil- dren without infection for control subjects. Sixty percent of the cases were MRSA and
40% MSSA. They found that SA was detected significantly more often in the rectum of children with abscesses (47%) than in the controls (1%). Nasal colonization was similar in both groups. Another interesting finding was that 88% of the SA recovered from the rectum was identical to the abscess culture. From this study, it seems that rectal coloniza- tion is actually a more important predictor of SSTI than nasal colonization, which may not be related at all.
Unfortunately, there are not good consensus guidelines regarding the use of mupirocin with or without bleach or chlorhexidine, so we rely on clinical experience and expert opinion. Most clinicians who see patients for recurrent MRSA infections will employ some of these techniques to try to help their patients when there is recurrent infection or transmission to other family members despite maximizing hygiene. It is common to try decolonization for all the members of a household when there is one member with recurrent disease as asymptomatic carriage is common as well. Hopefully, in the near future, we will have better guidance from the literature to help us make more evidence-based decisions for our patients.
Suggested Readings
Faden H, Lesse AJ, Trask J, et al. Importance of colonization site in the current epidemic of staphylococcal skin abscesses. Pediatrics. 2010;125(3):e618-e624.
Fisher RG, Chain RL, Hair PS, Cunnion KM. Hypochlorite killing of community-associated methicillin-resistant Staphylococcus aureus. Pediatr Infect Dis J. 2008;27(10):934-935.
Huang JT, Abrams M, Tlougan B, Rademaker A, Paller AS. Treatment of Staphylococcus aureus colonization in atopic dermatitis decreases disease severity. Pediatrics. 2009;123(5):e808-e814.