Of the topical medications available for decolonization, mupirocin has the highest efficacy, with eradication of MRSA and methicillin-sensitive Staphylococcus aureus (MSSA) colonization ranging from 81% to 93%. To increase the likelihood of successful decolonization, an antiseptic agent, such as chlorhexidine gluconate, may also be applied to the skin. Chlorhexidine gluconate is also commonly used to prevent other HAIs.
Neomycin is sometimes used for decolonization, but its efficacy for this purpose is questionable. There are also concerns about resistance, but it may be an option in cases of documented mupirocin resistance. Preparations that contain tea tree oil appear to be more effective for decolonization of skin sites than for nasal decolonization. Table 1 lists the topical antibiotics and antiseptics that may be utilized for decolonization, while Table 2 lists the oral medications that can be used for this purpose. Table 3 lists investigational agents being evaluated for their ability to decolonize patients.
It has been suggested that the patients who might derive the most benefit from decolonization are those at increased risk for developing a MRSA infection during a specific time interval. This would include patients who are admitted to the ICU for an acute illness and cardiothoracic surgery patients. A benefit from decolonization has also been observed in hemodialysis patients, who have an incidence of invasive MRSA infections 100 times greater than the general population. Otherwise, there are no data to support the routine use of decolonization in nonsurgical patients.
It is not uncommon for hospitals to screen patients admitted to the ICU for MRSA nasal colonization; in fact, screening is mandatory in nine states. If the nasal screen is positive, contact precautions are instituted. The decision about whether or not to initiate a decolonization protocol varies among different ICUs, but most do not carry out universal decolonization.
Some studies show decolonization is beneficial for ICU patients. These studies include a large cluster-randomized trial called REDUCE MRSA,3 which took place in 43 hospitals and involved 74,256 patients in 74 ICUs. The study showed that universal (i.e., without screening) decolonization using mupirocin and chlorhexidine was effective in reducing rates of MRSA clinical isolates, as well as bloodstream infection from any pathogen. Other studies have demonstrated benefits from the decolonization of ICU patients.4,5
Surgical Site Infections. Meanwhile, SSIs are often associated with increased mortality rates and substantial healthcare costs, including increased hospital lengths of stay and readmission rates. Staphylococcus aureus is the pathogen most commonly isolated from SSIs. In surgical patients, colonization with MRSA is associated with an elevated rate of MRSA SSIs. The goal of decolonization in surgical patients is not to permanently eliminate MRSA but to prevent SSIs by suppressing the presence of this organism for a relatively brief duration.
There is evidence that decolonization reduces SSIs for cardiothoracic surgeries.6 For these patients, it is cost effective to screen for nasal carriage of MRSA and then treat carriers with a combination of pre-operative mupirocin and chlorhexidine. It may be reasonable to delay cardiothoracic surgery in colonized patients who will require implantation of prosthetic material until they complete MRSA decolonization.
In addition to reducing the risk of auto-infection, another goal of decolonization is limiting the possibility of transmission of MRSA from a colonized patient to a susceptible individual; however, there are only limited data available that measure the efficacy of decolonization for preventing transmission.
Concerns about the potential hazards of decolonization therapy have impacted its widespread implementation. The biggest concern is that patients may develop resistance to the antimicrobial agents used for decolonization, particularly if they are used at increased frequency. Mupirocin resistance monitoring is valuable, but, unfortunately, the susceptibility of Staphylococcus aureus to mupirocin is not routinely evaluated, so the prevalence of mupirocin resistance in local strains is often unknown. Another concern about decolonization is the cost of screening and decolonizing patients.