Eradication of chronic methicillin-resistant Staphylococcus aureus infection in cystic fibrosis patients. An observational prospective cohort study of 11 patients.

BACKGROUND: Chronic airway infection with methicillin-resistant Staphylococcus aureus (MRSA) in patients with cystic fibrosis (CF) is an increasing clinical problem, and therapeutic options are limited. Because chronic infection with MRSA can be associated with accelerated decline in lung function, eradication of MRSA is attempted in most CF centres today. The aim of this observational prospective cohort study was to determine whether it is possible to eradicate MRSA from airways of CF patients using prolonged oral antibiotic combination therapy together with topical decolonization measures. RESULTS: Eleven CF patients, (median age: 9 years (range 1-43); median FEV1: 91%pred (95%CI 74%-100%pred)) who were chronically infected with MRSA, were treated daily for six months with rifampicin and fusidic acid orally. This study did not include a patient control group. Two patients had to switch to an alternative schedule, using rifampicin and clindamycin, due to the resistance pattern of MRSA. Topical decolonization measures were applied to all patients and included mupirocin-containing nasal ointment in both nostrils three times daily for five days and chlorhexidine hair and body wash once daily for five days. Microbiological eradication was achieved in all patients at the end of the six-month eradication protocol, even when significant time (range 18 months to 9 years) had elapsed since initial isolation. In only one patient MRSA reappeared in the six-month follow-up period after the initial study period. Side-effects, like nausea, vomiting and diarrhoea were seen in five out of eleven patients, but did not lead to therapy cessation. CONCLUSION: Chronic MRSA infection can be eradicated from respiratory tract samples using a six month dual antibiotic regimen and topical MRSA decolonization measures.