Persistent nasal methicillin-resistant staphylococcus aureus carriage in hemodialysis outpatients: a predictor of worse outcome

Abstract

Background: Nasal colonization with methicillin-resistant Staphylococcus aureus (MRSA) is a well defined risk factor for subsequent bacteremia and death in various groups of patients, but its impact on outcome in patients receiving long-term hemodialysis (HD) is under debate.

Methods: This prospective interventional cohort study (performed 2004 to 2010) enrolled 289 HD outpatients of an urban dialysis-unit. Nasal swab cultures for MRSA were performed in all patients upon first admission, at transfer from another dialysis facility or readmission after hospitalisation. Nasal MRSA carriers were treated in a separate ward and received mupirocin nasal ointment. Concomitant extra-nasal MRSA colonization was treated with 0.2% chlorhexidine mouth rinse (throat) or octenidine dihydrochloride containing antiseptic soaps and 2% chlorhexidine body washes (skin). Clinical data and outcome of carriers and noncarriers were systematically analyzed.

Results: The screening approach identified 34 nasal MRSA carriers (11.7%). Extra-nasal MRSA colonization was observed in 11/34 (32%) nasal MRSA carriers. History of malignancy and an increased Charlson Comorbidity Index were significant predictors for nasal MRSA carriers, whereas traditional risk factors for MRSA colonization or markers of inflammation or malnutrition were not able to discriminate. Kaplan-Meier analysis demonstrated significant survival differences between MRSA carriers and noncarriers. Mupirocin ointment persistently eliminated nasal MRSA colonization in 26/34 (73.5%) patients. Persistent nasal MRSA carriers with failure of this eradication approach had an extremely poor prognosis with an all-cause mortality rate >85%.

Conclusions: Nasal MRSA carriage with failure of mupirocin decolonization was associated with increased mortality despite a lack of overt clinical signs of infection. Further studies are needed to demonstrate whether nasal MRSA colonization represents a novel predictor of worse outcome or just another surrogate marker of the burden of comorbid diseases leading to fatal outcome in HD patients.

Figure 1

MRSA screening and outcome results in 289 HD outpatients. All prevalent outpatients that gave informed written consent and did not suffer from an active malignant disease (exclusion criterion) were enrolled. The 289 patients represent approximately 98% of all eligible outpatients that were treated during the study period in our dialysis unit.

Figure 2

Charlson Comorbidity index in nasal MRSA carriers and noncarriers. The age adjusted Charlson Comorbidity index showed significant differences between 31 nasal MRSA carriers and 193 noncarriers, where sufficient clinical data were available for analysis. Box-and-whisker plots indicating the median of the data set (middle line), the lower and upper quartiles (bottom and top of the box), and the range of values (whiskers) are showed.

Figure 3

Kaplan-Meier analysis in nasal MRSA carriers and noncarriers. Kaplan-Meier analysis showed significant survival differences between 34 nasal MRSA carriers and 198 noncarriers for all cause mortality. Of note, differences between both groups do not appear until after several years of follow-up.

Figure 4

Survival differences between patients with successful MRSA decolonization and persistent nasal MRSA carriers. Kaplan-Meier analysis showed significant survival differences between patients with successful MRSA decolonization and persistent MRSA carriers with failure of this approach. Of note, differences between both groups do not appear until after several years of follow-up.