Objective: Evaluation of the clinical and epidemiological features of Mycobacterium marinum infection in Queensland.
Design: Laboratory identification and in-vitro susceptibility tests of 29 isolates from the Queensland Health Department Tuberculosis Reference Laboratory were retrospectively gathered and followed up by contacting referring practitioners and obtaining clinical details of patients involved.
Subjects: 29 patients from whom M. marinum was isolated, with a male:female ratio of 3.1:1, and a mean age of 47.4 years.
Results: Of 26 patients for whom adequate information was available, 12 had evidence of involvement of deep tissues (including two cases of arthritis) and five suffered sporotrichoid spread of infection. The delay between onset of symptoms and consultation with a medical practitioner was five months (range, two weeks to two years), with a further mean delay to definitive diagnosis of 4.4 weeks. Cure was apparent in 22 of 23 cases. Chemotherapy alone was adequate in 11 cases, as was surgical intervention in three, while a combination approach was successful in eight cases. Trimethoprim/sulfamethoxazole was successful in seven of nine cases and combination rifampicin and ethambutol in six of seven. Tetracyclines were employed as single-agent therapy in nine patients and were effective in seven.
Conclusions: Synovitis was a common presenting feature of M. marinum infection in Queensland patients. Occupational and recreational exposure to salt or fresh water was common, and although this history was available to practitioners a mean delay to definitive diagnosis of 4.4 weeks still occurred. The data suggest that chemotherapy alone is often adequate, even with deep tissue involvement. Combinations of conventional antimycobacterial drugs may be the therapy of choice, especially for serious infections, although success was recorded with trimethoprim/sulfamethoxazole alone.