A case of Mycobacterium sherrisii pneumonia diagnosed by PCR/ESI-MS method

Mycobacterium sherrisii Lung Infection in a Brazilian Patient with Silicosis and a History of Pulmonary Tuberculosis

Nontuberculous mycobacteria (NTM) diseases became relevant with the emergence and spread of HIV and are also related to lung infection in non-HIV individuals with structural lung diseases. Mycobacterium sherrisii is a NTM first characterized in 2004. Only a few cases have been reported. The aim of this case report is to describe the first detailed case of infection with M. sherrisii in a patient with silicosis and history of pulmonary tuberculosis. A 50-year-old HIV-negative white male, previous smoker, with silicosis and a history of treated pulmonary tuberculosis developed a worsening of cough and expectoration pattern, and two sputum samples were positive for acid-fast bacilli. Presumptive treatment for pulmonary tuberculosis was initiated with rifampin, isoniazid, pyrazinamide, and ethambutol, but, at month 5 of treatment, despite correct medication intake and slight improvement of symptoms, sputum bacilloscopy remained positive. Sputum cultures were positive Mycobacterium sherrisii. Treatment regimen was altered to streptomycin (for 2 months), ethambutol, clarithromycin, rifabutin, and trimethoprim-sulfamethoxazole. M. sherrisii should be considered a possible etiological agent of lung infections in patients with pneumoconiosis and history of tuberculosis.

Microbiological features and clinical relevance of new species of the genus Mycobacterium

Nontuberculous mycobacteria (NTM) are present in the environment, mainly in water, and are occasionally responsible for opportunistic infections in humans. Despite the fact that NTM are characterized by a moderate pathogenicity, the diseases caused by NTM at various body sites are increasing on a worldwide level. Among over 150 officially recognized NTM species, only two or three dozen are familiar to clinicians, and even to most microbiologists. In this paper, approximately 50 new species described in the last 8 years are reviewed, and their role in human infections is assessed on the basis of reported clinical cases. The small number of reports concerning most of the "new" mycobacterial species is responsible for the widespread conviction that they are very rare. Their role is actually largely underestimated, mainly because they often remain unrecognized and misidentified. Aiming to minimize such bias, emphasis has been placed on more common identification pitfalls. Together with new NTM, new members of the Mycobacterium tuberculosis complex described in the last few years are also an object of the present review.