title: Infection due to a novel mycobacterium, mimicking multidrug-resistant Mycobacterium tuberculosis.
abstract: The treatment of multidrug-resistant tuberculosis (TB) requires the use, for long periods, of drugs liable to cause significant side effects. In the case of misdiagnosis of multidrug-resistant TB, the patient is exposed to toxic substances without any benefit. In low-income countries, where the microbiological diagnosis of TB relies on microscopy only, the misdiagnosis of multidrug-resistant TB is very frequent in patients persistently smear-positive despite anti-TB treatment, with the possibility of an infection due to non-tuberculous mycobacteria (NTM) being neglected. The isolation of a mycobacterium from the sputum of a Somali patient apparently confirmed the previous diagnosis of cavitary pulmonary disease. Preliminary investigations led, at first, to the strain being identified as multidrug-resistant Mycobacterium tuberculosis, with findings fully in agreement with the patient's history, which was characterized by repeated interruptions of anti-TB treatment. Thorough phenotypic and genotypic analyses led subsequently to the recognition that the strain was a previously unreported non-tuberculous mycobacterium. The patient, who was unresponsive to the anti-TB treatment, dramatically improved once a drug combination active against NTM was used. A major objective of this article is to alert the medical community to the risk, present also in settings in which sophisticated diagnostic techniques are used, that a cavitary infection due to NTM, and consequently not responding to the anti-TB standard regimen, will be mistaken for multidrug-resistant TB.
authors.affiliation: Regional Reference Centre for Mycobacteria, Careggi University Hospital, Florence, Italy. e.tortoli@libero.it
authors.forename: E
authors.initials: E
authors.lastname: Tortoli
authors.forename: P G
authors.initials: PG
authors.lastname: Rogasi
authors.forename: E
authors.initials: E
authors.lastname: Fantoni
authors.forename: C
authors.initials: C
authors.lastname: Beltrami
authors.forename: A
authors.initials: A
authors.lastname: De Francisci
authors.forename: A
authors.initials: A
authors.lastname: Mariottini
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D002851:Chromatography, High Pressure Liquid; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D008969:Molecular Sequence Data; D009165:Mycobacterium Infections, Nontuberculous / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology; D009171:Mycolic Acids / Q000032:analysis; D009170:Nontuberculous Mycobacteria / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification*; D010802:Phylogeny; D013902:Radiography, Thoracic; D017422:Sequence Analysis, DNA; D012998:Somalia; D014057:Tomography, X-Ray Computed; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D009171:Mycolic Acids