NONTUBERCULOUS MYCOBACTERIA IN CYSTIC-FIBROSIS

Background--The clinical significance of the presence of non-tuberculo us mycobacteria in the sputum of patients with cystic fibrosis is uncl ear. A retrospective case-control study was performed to assess possib le risk factors for non-tuberculous mycobacteria and its impact an cli nical status in patients with cystic fibrosis. Methods--The records of all patients attending the Leeds cystic fibrosis clinics who were pos itive for non-tuberculous mycobacteria were examined. Each case was ma tched with two controls for sex, age, and respiratory function at the time of the first non-tuberculous mycobacteria isolate. Details of res piratory function, nutritional status, antibiotic and corticosteroid t herapy, therapy, Shwachman-Kulczycki (S-K) score, Northern chest radio graphic scare, and the frequency of isolation of other bacteria and fu ngi were collected from two years before to two years after the first non-tuberculous mycobacteria isolate, The patients' genotype and the p resence of diabetes mellitus were also recorded. Results--Non-tubercul ous mycobacteria were isolated from 14 patients out of a cystic fibros is population of 372 (prevalence = 3.8%). No significant effect of non -tuberculous mycobacteria was seen on respiratory function, nutritiona l status, or S-K score. There was a significant association with the n umber of intravenous antibiotic: courses received before the first iso late with cases receiving, on average, twice as many courses as contro ls (cases 6.64, controls 2.86, 95% CI for difference 1.7 to 5.9). No s ignificant difference was seen between cases and controls for Northern scores, previous steroid therapy, or the incidence of diabetes mellit us. Conclusions--Non-tuberculous mycobacteria infection in patients wi th cystic fibrosis is uncommon and its clinical impact appears to be m inimal over a two year period. Frequent intravenous antibiotic biotic usage is a possible risk factor for colonisation with non-tuberculous mycobacteria.