Clinical significance and epidemiology of non-pigmented rapidly growing mycobacteria in a university hospital

SummaryObjetivesTo study the clinical significance and epidemiology of Non-pigmented rapidly growing mycobacteria (NPRGM) during a 13-year period.MethodsWe performed a retrospective study of patients with isolates of NPRGM to evaluate their clinical significance. We also analyzed the strains using Randomly Amplified Polymorphic DNA (RAPD) analysis to evaluate the relationship between strains.ResultsBetween 1990 and 2003, 65 patients had an isolate of NPRGM. Twenty of them were considered significant (19 cases) or doubtful (1 case). Many cases were skin and soft tissue infections. Six cases were foreign-body related. All the patients recovered with antibiotic therapy and removal of the foreign body. All the patients were apparently unrelated, despite 56.9% of the isolates were detected between 1995 and 1997.RAPD analysis was performed on 43 strains, and showed only a cluster of two Mycobacterium chelonae isolates. Both of them were related with contamination of a laboratory reactive, and were considered non-significant.ConclusionIn our hospital, almost one-third of the isolates of NPRGM were significant, being this percentage higher for skin and soft tissue isolates. Patients were cured with antibiotic therapy, but the removal of foreign bodies appeared to be necessary for a good outcome. A minor psudo-outbreak was detected. No predominant strain was detected.