Identification of Mycobacterium shimoidei by molecular techniques: case report and summary of the literature

Abstract

A 53-year-old woman from Melbourne, Australia, with squamous cell carcinoma of the oesophagus was shown by computed tomography (CT) scan to have a left apical cavity and inflammatory changes in the right lung consistent with aspiration. Acid-fast bacilli isolated from bronchial washings were identified biochemically first as Mycobacterium terrae, but later as M. shimoidei on the basis of 1) restriction fragment analysis and 2) sequencing of polymerase chain reaction (PCR) amplified 16S rDNA. Nine other descriptions of patients with M. shimoidei isolates were collated. The salient feature of isolates considered to be pathogenic was pulmonary cavitation. Most patients had underlying lung disease, including past tuberculosis or malignancy. Six of eight patients died of progressive respiratory illness, although the contribution of M. shimoidei was not always clear, and two patients improved. One patient with the acquired immune-deficiency syndrome (AIDS) died with Salmonella enteritidis and M. shimoidei isolated from blood cultures. One isolate was regarded as a coloniser. There are insufficient clinical or sensitivity data on which to base recommendations for therapy, but a combination of ethambutol, rifabutin and pyrazinamide could be considered.