Background Species of Non-Tuberculosis Mycobacterium (NTM), mainly Mycobacterium abscessus (M abscessus) is of increasing concern in Cystic Fibrosis (CF). M abscessus are present in the CF lungs as part of the complex microbiological community. The mode of growth of M abscessus in vitro is in biofilms; this maybe a contributing factor for the resistance to antimicrobial agents. Lung infections with M abscessus is a major concern in CF patients, as it is difficult to treat them. It has been described that, fatal infections are likely to occur after lung transplantations; therefore pre-transplant colonisation with M abscessus has become a relative contraindication to lung transplantation. NTM are recognised pathogens in the CF airways, but associations with clinical outcomes still remains unclear.

Objectives The aim of the present study was to determine whether adult CF patients with pulmonary NTM infection have worse clinical outcomes, when compared to a matched group of CF patients who have never had NTM isolated. Additionally, the study also aims to determine what proportion of the overall bacterial community is NTM compared to other bacteria.

Method Clinical data were collected from 12 spontaneously expectorating CF patients who cultured M abscessus in the sputum since they were first infected with M abscessus, and 24 matched controls who have CF, but never been infected with M abscessus. Student unpaired t-test was used to compare the mean forced expiratory volume (FEV₁) per year between the two groups.

Results Data from 36 individuals were studied. Cases and controls were well matched. Mean absolute decline in FEV₁ was 100 ml/year (SD±0.19) in cases and 79 ml/year (SD±0.19) in controls. Student unpaired t-test was not significant (0.73). Mean absolute percentage predicted decline in FEV₁ was 3.85% (SD±5.62) in cases and 2.78% (SD±6.58) in controls. Student unpaired t-test was not significant (0.62).

Conclusion These results indicate that there is a small decline in mean FEV₁ per year between the two groups; M abscessus and the controls, but the difference is statistically and clinically insignificant.