Mycobacterium malmoense infections in Scotland: an increasing problem

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Pulmonology

Background:

• Mycobacterium malmoense infections present clinically similarly to pulmonary tuberculosis.
• Chronic chest conditions, especially chronic airflow obstruction, are common comorbidities.
• In vitro drug resistance patterns were observed for M. malmoense.

Purpose of the Study:

• To describe the clinical features and treatment outcomes of Mycobacterium malmoense infections in Scotland.
• To evaluate the efficacy of standard antituberculosis chemotherapy regimens.
• To provide recommendations for the management of M. malmoense infections.

Main Methods:

• Retrospective review of case notes and radiographs for 19 patients diagnosed between 1982-1984.
• Assessment of in vitro drug susceptibility testing.
• Analysis of treatment responses and relapse rates.

Main Results:

• Clinical presentation was indistinguishable from pulmonary tuberculosis.
• Significant in vitro resistance to isoniazid, pyrazinamide, and p-aminosalicylic acid was noted.
• Early response to combination chemotherapy was observed, but relapse occurred in 5/9 patients receiving less than nine months of ethambutol.

Conclusions:

• Treatment with ethambutol for at least nine months is associated with more satisfactory outcomes.
• In suspected tuberculosis cases, ethambutol should be included in the initial regimen pending culture results.
• The incidence of M. malmoense infections appears to be increasing relative to tuberculosis.