Mycobacteriumdiagnostics: from the primitive to the promising

Abstract

The field of clinical microbiology has been revolutionised by genomic and proteomic methods, which have facilitated more rapid diagnosis and characterisation of infection in many cases. In contrast, mycobacteriological evolution has tended to retain the traditional methods of smear microscopy for detection of acid-fast bacilli to indicate mycobacteria, along with culture, and in synergy with more modern molecular methods. Thus, efforts have been focused on reducing the time to diagnosis of infection, while increasing the amount of diagnostic information available, including more definitive speciation, and more rapid susceptibility test results. Although smear microscopy remains a mainstay for the laboratory-based diagnosis of mycobacterial infection, molecular testing has vastly reduced the time needed for identification of Mycobacterium tuberculosis in particular, when compared with traditional culture-based techniques. Molecular methods may also yield antimicrobial susceptibility results through testing for the most common resistance-inducing mutations to some of the antimicrobial agents of choice. However, the diversity of resistance mutations already characterised suggests that these currently-available molecular detection systems should be accompanied by culture-based susceptibility testing. This review compares the efficacy of microscopic, phenotypic, proteomic and genotypic methods available for mycobacterial diagnosis. The diversity of methods currently in use reflects the complexity of this area of diagnostic microbiology.

Coinfection of disseminated Talaromyces marneffei and Mycobacteria kansasii in a patient with papillary thyroid cancer

“…Unfortunately, our patient did not undergo strain identification at local hospitals, even though studies provided evidence that infections with several strains of NTM including M. kansasii also could result in a positive T-SPOT.TB result. [3] In addition, the lung lesions were not absorbed completely after antifungal therapy during her first hospitalization, indicating the potential infections with 2 or more pathogens. Thus, in our opinion, the mixed infections of disseminated T. marneffei and M. kansasii were to occur concurrently instead of sequentially.…”

Temporal Expression of Peripheral Blood Leukocyte Biomarkers in a Macaca fascicularis Infection Model of Tuberculosis; Comparison with Human Datasets and Analysis with Parametric/Non-parametric Tools for Improved Diagnostic Biomarker Identification

“…Methods used for TB diagnosis have not changed significantly in recent years in many routine diagnostic laboratories [ 14 ] and current tests are still somewhat inadequate. There is substantial evidence that TB diagnosis is subject to significant error, with up to 52% under-diagnosis reported in some studies using comparative indices between TB diagnosis methods as measured against autopsy observations [ 11 ].…”

Importance of using several molecular targets for the appropriated identification of Mycobacterium marinum

“…To this is added the increasing trend in the number of communications on the role of new species of mycobacteria in human and animal health. 2,46 Additionally, the characteristics of the case lead us to suggest, as it has been indicated by O'Connor et al 7 , that is very important to keep and continuing to use the bacteriological techniques as the first line of identification and to apply and include more specific and sensitive molecular tests that exploit different mycobacterial targets with the aim to broaden the specificity of the mycobacterial identification.…”

“…6 Although molecular methods require also specialized laboratories and resources, they are more popular and accessible, existing an increasing trend to use them in laboratories but without displacing conventional methods of culture and biochemical identification as the first approach to the identification and amplification of mycobacteria populations. 7 Furthermore, molecular tests are fundamental since the selection of drugs and treatment schemes against mycobacterial diseases are based on the genetic identification of the mycobacterial species involved. 8 As a mycobacteria grouped into NTM, M. marinum is considered as saprophyte specie, capable not only to infect about 150 species of freshwater and saltwater fish, but also to produce infections in the soft tissues of human being.…”