MRSA: to decolonize or not to decolonize?

Although the Dutch system of "search and destroy" has given the Netherlands one of the lowest rates of MRSA colonization and infection, testing everyone in a hospital for MRSA and subsequently treating is not generally recommended. Numerous studies have advocated colonization screening and mupirocin decolonization for outbreaks, but it has not been proven to reduce infections in endemic areas. This study from Kauffman, et al is widely cited and makes a few key points:
1) reduction of MRSA colonization is not necessarily correlated to reduction of MRSA infection in facilities without high infection rates
2) mupirocin resistance is increasing with prolonged use
3) intranasal mupirocin is only an effective decolonizer if all other colonized areas of the body are treated with mupirocin as well

Mupirocin is widely used, especially in dermatology, for recurrent superficial infections and wound healing in high-risk individuals. It will be interesting to follow the trend of mupirocin resistance amongst strains of MRSA. Mupirocin is by far the most effective agent in decolonization although new medications are under review. There are two types of mupirocin resistance, high-level (plasmid-mediated) and low-level (still mupirocin susceptible at the commonly used dosage). High-level resistance is most concerning and was shown to increase with widespread mupirocin use in the above study.

Kauffman CA, Bradley SF, Terpenning MS. Methicillin-resistant Staphylococcus aureus in long-term care facilities. Infect Control Hosp Epidemiol. 1990;11:600–603.

Scott and White to test all patients for MRSA

Now here's an interesting piece of news! Scott & White hospitals in Round Rock and Temple, TX are going to start testing all patients for MRSA colonization through nasal cultures. This will surely provide some interesting epidemiological data, but the bigger question is, what will they do with this information? Are they going to try to treat everyone who is colonized? Study after study does not recommend this unless the patient has recurring infections. This is going to be an important question in the coming years, should asymptomatic MRSA carriers be treated? The Netherlands maintains one of the world's lowest MRSA colonization and infection rates by screening for MRSA upon hospital admission and subsequently treating all colonizers. Does the US have the resources for this? Also, with mupirocin-resistant MRSA emergence, is it a waste of resources to treat patients who are asymptomatic? And would treatment involve just topical antibiotics? Antiseptic washes? Oral antibiotics? I'm eager to see how this information is handled and if hospital MRSA infection rates are decreased.

CA MRSA in dermatology

Community-acquired methicillin Staphylococcus aureus (CA MRSA) is a relatively recent infection (the last decade). It is particularly relevant to dermatologists as these bacterial strains present most commonly as skin or soft tissue infections. With the recent media blitz surrounding MRSA, it is difficult to discern the medical facts from the news reports. The American Academy of Dermatology has some valuable Talking Points and FAQs that are useful to both patients and healthcare professionals alike.

Pets as Staph carriers

Many studies have been done showing that dogs, cats, and horses can be colonized or infected with methicillin-resistant staph aureus (MRSA).

Here are some definitions:
1. colonized- one carries the bacteria, but doesn't have any adverse effects from it. it just lives benignly usually in the nose or other mucosal surfaces
2. infected- the bacteria is causing adverse effects

MRSA is particularly dangerous because it is often resistant to multiple antibiotics and can be hard to treat. It is spread easily through hospitals and the community. And apparently, it can be spread via pets.

From what I've read, it looks like dogs and cats can pick up human strains of MRSA from their owners and either be colonized or infected. They can then pass the bacteria back to humans they contact (licking, petting, rubbing noses). What makes this particularly dangerous is that there are genes in bacteria that allow them to be resistant to different antibiotics. For example, the mecA gene makes Staph aureus resistant to methicillin. Well, these genes can be transferred from one bacteria to another. Dogs' natural flora includes Staph intermedius, which has been shown to have a high resistance to multiple drugs. And if dogs are harboring all these bacteria, they can breed MRSA strains that are resistant to multiple antibiotics, transfer them to humans, and make an infection that is very difficult to treat.

(There's no reference here because hopefully I'll be able to add the paper I'm working on as a reference when it's done :)

Does antibiotic ointment really help wounds heal?

Not any better than plain old Vaseline.

According to...

Smack DP, Harrington AC, Dunn C, Howard RS, Szkutnik AJ, Krivda SJ. Infection and allergy incidence in ambulatory surgery patients using white petrolatum vs. bacitracin ointment. A randomized controlled trial. JAMA 1996;276:972-7.

... bacitracin (an antibiotic used in triple antibiotic ointment or Polysporin) usage after outpatient dermatologic procedures has a statistically similar rate of infection to white petrolatum (AKA Vaseline) usage. In fact, white petrolatum not only kept infection rates very low, but it also had no allergic reactions, unlike bacitracin.

1 oz of bacitracin ointment costs about $3
13 oz of white petrolatum costs about $3

It appears that these ointments serve as an occlusive dressing and keep the wound clean and moist.

I'm using Neosporin, but my wound keeps getting worse!

I saw two patients today with the same complaint and the same problem. Neosporin is an antibiotic ointment containing neomycin, an aminoglycoside antibiotic. Neomycin can be used topically or orally, but it is most commonly used as a topical medication. Neosporin is mainly used as an agent to help with wound healing. So why did these two patients have what appeared to be normal wounds that were actually getting worse when they used Neosporin?

Neomycin is one of the top 10 topical allergens in the US. The allergic reaction usually presents as a red, raw area similar to eczema. It will look like the wound is spreading or getting worse instead of healing. Just stop using the Neosporin and be sure to avoid all ointments (like triple antibiotic ointment) that contain Neomycin as well. Also, people who are allergic to Neomycin show a high incidence of allergic reactions to Bacitracin, another topical antibiotic (usually sold as Polysporin). Finally, it's important to remember that you had this allergic reaction to Neosporin because you may be allergic to oral medications that are in the same class of drugs. But when you take the oral aminoglycosides, you could have an eczematous reaction over your whole body or even have anaphylactic shock. Look back at my previous post about Vaseline being used for wound healing. It's a great alternative for people who are allergic to Neomycin or Bacitracin.



Hopefully my paper will be accepted and I'll use it as the reference here :)