A Case of False-PositiveMycobacterium tuberculosisCaused byMycobacterium celatum

Abstract

Mycobacterium celatum is a nontuberculous mycobacterium shown to cause symptoms similar to pulmonary M. tuberculosis. Certain strains have been shown to cross-react with the probes used to detect M. tuberculosis, making this a diagnostic challenge. We present a 56-year-old gentleman who developed signs and symptoms of lung infection with computed tomography scan of the chest showing right lung apex cavitation. Serial sputum samples were positive for acid-fast bacilli and nucleic acid amplification testing identified M. tuberculosis ribosomal RNA, resulting in treatment initiation. Further testing with high performance liquid chromatography showed a pattern consistent with M. celatum. This case illustrates the potential for M. celatum to mimic M. tuberculosis in both its clinical history and laboratory testing due to the identical oligonucleotide sequence contained in both. An increasing number of case reports suggest that early reliable differentiation could reduce unnecessary treatment and public health intervention associated with misdiagnosed tuberculosis.

Attenuated tuberculin skin test responses associated with Mycobacterium intracellulare sputum colonization in an adolescent TB prevalence survey in Western Kenya

“…We isolated slow-growing M. celatum in 14 cases, all of whom were immunocompetent, which is an uncommon finding [ 39 – 42 ]. M. celatum has also been reported as a cause of false positive Mtb nucleic acid amplification [ 43 , 44 ]. We also isolated M. ulcerans from one immunocompetent participant.…”

A rare case of pulmonary mycobacteriosis caused by rifabutin resistant Mycobacterium celatum and review of the literature

“…A negative T-SPOT test and M. tuberculosis complex DNA test however disproved this diagnosis and were strongly suggestive of atypical mycobacteriosis, underlying importance of all mentioned methods in routine diagnostic process. Nevertheless, false positive cases of M. tuberculosis complex DNA test have been described using nucleic acid amplification methods causing a false diagnose and consequent therapy, due to a cross-reactivity of certain Mycobacteria strains with M. tuberculosis probe [ 13 , 14 ]. Microbiological culture analysis for atypical mycobacteria can however take up to six weeks, therapy against atypical mycobacteriosis should immediately be started as soon as the positive microscopical examination and negative M. tuberculosis complex DNA test is available.…”

TB or not TB? Mycobacterium celatum mimicking Mycobacterium tuberculosis : A case of mistaken identity

“…Infection with M. celatum or M. tuberculosis produce similar symptoms, including cough, weight loss, lung infiltrates, and cavitary lung lesions [ 19 ], likely reflecting similar pathogenic mechanisms. Complicating diagnosis further is the finding that M. celatum types 1 and 3 cross-react with gene probes used to detect M. tuberculosis , which has made this pathogen a challenge to diagnose [ 18 ]. Thus, M. tuberculosis complex and M. avium complex DNA is currently detected by real-time polymerase chain reaction (PCR), and negative cultures are further characterized using matrix-assisted later desorption/ionization-time of flight mass spectrometry (MALDI-TOF).…”