Molecular characterization of Mycobacterium kansasii isolates in the State of São Paulo between 1995-1998

A Murine Model of Mycobacterium kansasii Infection Reproducing Necrotic Lung Pathology Reveals Considerable Heterogeneity in Virulence of Clinical Isolates

Among non-tuberculous mycobacteria, Mycobacterium kansasii is one of the most pathogenic, able to cause pulmonary disease indistinguishable from tuberculosis in immunocompetent susceptible adults. The lack of animal models that reproduce human-like lung disease, associated with the necrotic lung pathology, impairs studies of M. kansasii virulence and pathogenicity. In this study, we examined the ability of the C57BL/6 mice, intratracheally infected with highly virulent M. kansasii strains, to produce a chronic infection and necrotic lung pathology. As a first approach, we evaluated ten M. kansasii strains isolated from Brazilian patients with pulmonary disease and the reference strain M. kansasii ATCC 12478 for virulence-associated features in macrophages infected in vitro; five of these strains differing in virulence were selected for in vivo analysis. Highly virulent isolates induced progressive lung disease in mice, forming large encapsulated caseous granulomas in later stages (120–150 days post-infection), while the low-virulent strain was cleared from the lungs by day 40. Two strains demonstrated increased virulence, causing premature death in the infected animals. These data demonstrate that C57BL/6 mice are an excellent candidate to investigate the virulence of M. kansasii isolates. We observed considerable heterogeneity in the virulence profile of these strains, in which the presence of highly virulent strains allowed us to establish a clinically relevant animal model. Comparing public genomic data between Brazilian isolates and isolates from other geographic regions worldwide demonstrated that at least some of the highly pathogenic strains isolated in Brazil display remarkable genomic similarities with the ATCC strain 12478 isolated in the United States 70 years ago (less than 100 SNPs of difference), as well as with some recent European clinical isolates. These data suggest that few pathogenic clones have been widely spread within M. kansasii population around the world.

Molecular epidemiology of Mycobacterium tuberculosis in Brazil before the whole genome sequencing era: a literature review

Molecular-typing can help in unraveling epidemiological scenarios and improvement for disease control strategies. A literature review of Mycobacterium tuberculosis transmission in Brazil through genotyping on 56 studies published from 1996-2019 was performed. The clustering rate for mycobacterial interspersed repetitive units - variable tandem repeats (MIRU-VNTR) of 1,613 isolates were: 73%, 33% and 28% based on 12, 15 and 24-loci, respectively; while for RFLP-IS6110 were: 84% among prison population in Rio de Janeiro, 69% among multidrug-resistant isolates in Rio Grande do Sul, and 56.2% in general population in São Paulo. These findings could improve tuberculosis (TB) surveillance and set up a solid basis to build a database of Mycobacterium genomes.

Phylogenomics reveal that Mycobacterium kansasii subtypes are species-level lineages. Description of Mycobacterium pseudokansasii sp. nov., Mycobacterium innocens sp. nov. and Mycobacterium attenuatum sp. nov

Among the species Mycobacterium kansasii, seven subtypes have been previously reported based on the PCR and the restriction fragment length polymorphism of the gene hsp65. Here, we used whole-genome sequencing to refine M. kansasii taxonomy and correct multiple inconsistencies. Average nucleotide identity (ANI) values between M. kansasii subtypes ranged from 88.4 to 94.2 %, lower than the accepted 95-96 % cut-off for species delineation. In addition, Mycobacterium gastri was closer to the M. kansasii subtypes 1, 2, 3, 4 and 5 than M. kansasii subtype 6. The recently described species Mycobacterium persicum shared 99.77 % ANI with M. kansasii subtype 2. Consistent with the ANI results, the digital DNA-DNA hybridization value was below the 70 % threshold for species delineation between subtypes and above it within subtypes as well as between subtype 2 and M. persicum. Furthermore, core-genome phylogeny confirmed the current M. kansasii species to be polyphyletic. Hence, we propose (i) Mycobacterium pseudokansasii sp. nov., replacing subtype 3, with the type strain MK142^T(=CCUG 72128^T=DSM 107152^T), (ii) Mycobacterium innocens sp. nov., replacing subtype 5, with the type strain MK13^T (=CCUG 72126^T=DSM 107161^T), and (iii) Mycobacterium attenuatum sp. nov., replacing subtype 6, with the type strain MK41^T(=CCUG 72127^T=DSM 107153^T). Subtype 4 represents a new species-level lineage based on the genomic data but no strain was available. No genome sequence or strain was available for subtype 7. The proposed nomenclature will facilitate the identification of the most pathogenic subtype 1 as M. kansasii by clinicians while the new species names suggest the attenuated pathogenicity of the other subtypes.

Clinical, radiological and molecular features of Mycobacterium kansasii pulmonary disease

BACKGROUND

Studies concerning sociodemographic, clinical, and laboratory features of Mycobacterium kansasii pulmonary disease are few and based on small patient cohorts. The objective of the study was to evaluate characteristics of patients from whom M. kansasii respiratory isolates were recovered and to provide a detailed description of M. kansasii disease.

BASIC PROCEDURES

Retrospective review of electronic medical records of all patients for whom at least one positive M. kansasii culture was obtained at the Department of Internal Medicine, Pulmonology and Allergology of the Warsaw Medical University between the year 2000 and 2015. Patients were categorized as having mycobacterial disease or as isolation cases based on the American Thoracic Society and Infectious Diseases Society of America (ATS/IDSA) diagnostic criteria.

MAIN FINDINGS

The study comprised of 105 patients (63 females, 42 males, mean age 64.6 ± 17.8 years). Of these, 86 (81.9%) were diagnosed as having M. kansasii disease. The proportion of positive smear microscopy was significantly higher in patients with M. kansasii disease compared to M. kansasii isolation (P < 0.001). There were no statistically significant differences between M. kansasii disease and isolation cases in terms of clinical symptoms or comorbidities. Patients with M. kansasii disease presented most commonly (43/86, 50%) fibro-cavitary disease upon radiology. Lesion distribution usually showed bilateral upper lobe involvement. Among the 191 isolates genotyped, all were identified as M. kansasii type I.

PRINCIPAL CONCLUSIONS

The findings from this study support the relaxation of the diagnostic criteria for the definition of M. kansasii disease, set forth by ATS/IDSA. Molecular typing did not differentiate isolates from patients with true disease from those with isolation only; the role of bacterial virulence factors thus remains elusive.

Molecular typing of Mycobacterium kansasii using pulsed-field gel electrophoresis and a newly designed variable-number tandem repeat analysis

Molecular epidemiological studies of Mycobacterium kansasii are hampered by the lack of highly-discriminatory genotyping modalities. The purpose of this study was to design a new, high-resolution fingerprinting method for M. kansasii. Complete genome sequence of the M. kansasii ATCC 12478 reference strain was searched for satellite-like repetitive DNA elements comprising tandem repeats. A total of 24 variable-number tandem repeat (VNTR) loci were identified with potential discriminatory capacity. Of these, 17 were used to study polymorphism among 67 M. kansasii strains representing six subtypes (I-VI). The results of VNTR typing were compared with those of pulsed-field gel electrophoresis (PFGE) with AsnI digestion. Six VNTRs i.e. (VNTR 1, 2, 8, 14, 20 and 23) allow to differentiate analyzed strains with the same discriminatory capacities as use of a 17-loci panel. VNTR typing and PFGE in conjunction revealed 45 distinct patterns, including 11 clusters with 33 isolates and 34 unique patterns. The Hunter-Gaston's discriminatory index was 0.95 and 0.66 for PFGE and VNTR typing respectively, and 0.97 for the two methods combined. In conclusion, this study delivers a new typing scheme, based on VNTR polymorphism, and recommends it as a first-line test prior to PFGE analysis in a two-step typing strategy for M. kansasii.

The looming tide of nontuberculous mycobacterial infections in Portugal and Brazil

Nontuberculous mycobacteria (NTM) are widely disseminated in the environment and an emerging cause of infectious diseases worldwide. Their remarkable natural resistance to disinfectants and antibiotics and an ability to survive under low-nutrient conditions allows NTM to colonize and persist in man-made environments such as household and hospital water distribution systems. This overlap between human and NTM environments afforded new opportunities for human exposure, and for expression of their often neglected and underestimated pathogenic potential. Some risk factors predisposing to NTM disease have been identified and are mainly associated with immune fragilities of the human host. However, infections in apparently immunocompetent persons are also increasingly reported. The purpose of this review is to bring attention to this emerging health problem in Portugal and Brazil and to emphasize the urgent need for increased surveillance and more comprehensive epidemiological data in both countries, where such information is scarce and seriously thwarts the adoption of proper preventive strategies and therapeutic options.

Molecular characterisation of clinical and environmental isolates of Mycobacterium kansasii isolates from South African gold mines

Mycobacterium kansasii (M. kansasii) is a major cause of non-tuberculous mycobacterial pulmonary disease in the South African gold-mining workforce, but the source of infection and molecular epidemiology are unknown. This study investigated the presence of M. kansasii in gold and coal mine and associated hostel water supplies and compared the genetic diversity of clinical and environmental isolates of M. kansasii. Five M. kansasii and ten other potentially pathogenic mycobacteria were cultured mainly from showerhead biofilms. Polymerase chain reaction-restriction analysis of the hsp65 gene on 196 clinical and environmental M. kansasii isolates revealed 160 subtype I, eight subtype II and six subtype IV strains. Twenty-two isolates did not show the typical M. kansasii restriction patterns, suggesting that these isolates may represent new subtypes of M. kansasii. In contrast to the clonal population structure found amongst the subtype I isolates from studies in other countries, DNA fingerprinting of 114 clinical and three environmental subtype I isolates demonstrated genetic diversity amongst the isolates. This study demonstrated that showerheads are possible sources of M. kansasii and other pathogenic non-tuberculous mycobacterial infection in a gold-mining region, that subtype I is the major clinical isolate of M. kansasii strain and that this subtype exhibits genetic diversity.

Short communication: subtyping of Mycobacterium kansasii by PCR-restriction enzyme analysis of the hsp65 gene

Mycobacterium kansasii is one of the most common causes of pulmonary disease resulting from nontuberculous mycobacteria (NTM). It is also the most frequently isolated NTM species from clinical specimens in Poland. The aim of this study was to investigate the distribution of M. kansasii subtypes among patients suspected of having pulmonary NTM disease. Fifty clinical isolates of M. kansasii recovered from as many patients with suspected mycobacterial lung disease between 2000 and 2010 in Poland were genotyped by PCR-restriction enzyme analysis (PCR-REA) of partial hsp65 gene. Mycobacterium kansasii subtype I was the only genotype to be identified among the isolates, both disease-associated and non-disease-associated. Isolation of M. kansasii subtype I from clinical specimens may be indicative of infection but may also merely represent colonization.

Clinical and therapeutic features of pulmonary nontuberculous mycobacterial disease, Brazil, 1993-2011

To identify clinical and therapeutic features of pulmonary nontuberculous mycobacterial (PNTM) disease, we conducted a retrospective analysis of patients referred to the Brazilian reference center, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil, who received a diagnosis of PNTM during 1993–2011 with at least 1 respiratory culture positive for NTM. Associated conditions included bronchiectasis (21.8%), chronic obstructive pulmonary disease (20.7%), cardiovascular disease (15.5%), AIDS (9.8%), diabetes (9.8%), and hepatitis C (4.6%).Two patients had Hansen disease; 1 had Marfan syndrome. Four mycobacterial species comprised 85.6% of NTM infections: Mycobacterium kansasii, 59 cases (33.9%); M. avium complex, 53 (30.4%); M. abscessus, 23 (13.2%); and M. fortuitum, 14 (8.0%). A total of 42 (24.1%) cases were associated with rapidly growing mycobacteria. In countries with a high prevalence of tuberculosis, PNTM is likely misdiagnosed as tuberculosis, thus showing the need for improved capacity to diagnose mycobacterial disease as well as greater awareness of PNTM disease prevalence.

hsp65 PCR-restriction analysis (PRA) with capillary electrophoresis for species identification and differentiation of Mycobacterium kansasii and Mycobacterium chelonae-Mycobacterium abscessus group

OBJECTIVES

The aim of the present study was to identify and differentiate Mycobacterium kansasii and Mycobacterium chelonae-Mycobacterium abscessus group strains isolated from clinical and environmental sources in different countries.

METHODS

PCR-restriction analysis of the hsp65 gene (PRA) with automated capillary electrophoresis was applied to the isolates previously identified by conventional biochemical testing and the molecular INNO-LiPA MYCOBACTERIA assay.

RESULTS

PRA performed very well in comparison with the two other methods (96.4% concordance). Among 27 M. kansasii isolates, this method detected five genetic types, of which type 1 represented the most common clinical isolate, as it is worldwide. PRA differentiated 29 M. chelonae-M. abscessus group isolates into Mycobacterium immunogenum type 2 (n=13), M. chelonae (n=12), and M. abscessus types 1 (n=1) and 2 (n=1). M. immunogenum was the most frequent (69%) isolate from humans, but only one of 11 cases was clinically significant. M. chelonae was the most commonly (83%) recovered from water. PRA also identified two isolates with hsp65 alleles representing previously unreported patterns.

CONCLUSIONS

PRA based on automated capillary electrophoresis is a rapid, simple, and reliable method for the identification and differentiation of both clinically relevant and environmental isolates of M. kansasii and M. chelonae-M. abscessus group.

Isolamento de micobactérias não-tuberculosas em São José do Rio Preto entre 1996 e 2005

OBJETIVO: Estudar a ocorrência de micobactérias não-tuberculosas e a variabilidade das espécies isoladas na região atendida pelo Instituto Adolfo Lutz-Regional de São José do Rio Preto-no período entre 1996 e 2005, assim como mostrar a importância do diagnóstico laboratorial. MÉTODOS: A partir de amostras pulmonares e extrapulmonares, foi realizado o isolamento de micobactérias, e estas foram identificadas por métodos fenotípicos e pelo método molecular polymerase chain reaction-restriction enzyme analysis. RESULTADOS: Foram isoladas 317 cepas de micobactérias não-tuberculosas: complexo Mycobacterium avium, 182 (57,4%); M. gordonae, 33 (10,4%); M. fortuitum, 25(7,9%); M. chelonae, 8 (2,5%); complexo M. terrae, 8 (2,5%); M. kansasii, 7 (2,2%); e espécies menos freqüentes, 54 (17%). No período, foram caracterizados 72 casos (33,3%) de micobacterioses, de acordo com os critérios bacteriológicos estabelecidos pela American Thoracic Society (2007).Desses, complexo M. avium foi responsável por 56 casos, sendo que 29 (51,8%) foram caracterizados como doença disseminada. M. fortuitum foi responsável por 6 casos; M. gordonae, 3; M. chelonae, 2; M. abscessus, 1; M. kansasii, 1; M. intracellulare, 1; M. malmoense, 1; e Mycobacterium ssp., 1. CONCLUSÕES: Os resultados obtidos mostraram a importância do diagnóstico bacteriológico das micobacterioses, pois a identificação das espécies possibilita a introdução de um tratamento adequado precocemente.

Reliable identification of mycobacterial species by PCR-restriction enzyme analysis (PRA)-hsp65 in a reference laboratory and elaboration of a sequence-based extended algorithm of PRA-hsp65 patterns

BACKGROUND

Identification of nontuberculous mycobacteria (NTM) based on phenotypic tests is time-consuming, labor-intensive, expensive and often provides erroneous or inconclusive results. In the molecular method referred to as PRA-hsp65, a fragment of the hsp65 gene is amplified by PCR and then analyzed by restriction digest; this rapid approach offers the promise of accurate, cost-effective species identification. The aim of this study was to determine whether species identification of NTM using PRA-hsp65 is sufficiently reliable to serve as the routine methodology in a reference laboratory.

RESULTS

A total of 434 NTM isolates were obtained from 5019 cultures submitted to the Institute Adolpho Lutz, Sao Paulo Brazil, between January 2000 and January 2001. Species identification was performed for all isolates using conventional phenotypic methods and PRA-hsp65. For isolates for which these methods gave discordant results, definitive species identification was obtained by sequencing a 441 bp fragment of hsp65. Phenotypic evaluation and PRA-hsp65 were concordant for 321 (74%) isolates. These assignments were presumed to be correct. For the remaining 113 discordant isolates, definitive identification was based on sequencing a 441 bp fragment of hsp65. PRA-hsp65 identified 30 isolates with hsp65 alleles representing 13 previously unreported PRA-hsp65 patterns. Overall, species identification by PRA-hsp65 was significantly more accurate than by phenotype methods (392 (90.3%) vs. 338 (77.9%), respectively; p < .0001, Fisher's test). Among the 333 isolates representing the most common pathogenic species, PRA-hsp65 provided an incorrect result for only 1.2%.

CONCLUSION

PRA-hsp65 is a rapid and highly reliable method and deserves consideration by any clinical microbiology laboratory charged with performing species identification of NTM.

Application of the hsp65 PRA method for the rapid identification of mycobacteria isolated from clinical samples in Belgium

Biochemical identification of mycobacteria is slow and many times fail to produce correct results. We compared PCR-restriction fragment length polymorphism analysis (PRA) of hsp65 and biochemical methods for the identification of mycobacteria from human samples in Belgium. PRA was found useful in the identification of mycobacteria and simple to implement as a quick method in the laboratory.

Derrame pleural por micobactéria não tuberculosa

O Mycobacterium kansasii, micobactéria não tuberculosa, pode causar doença pulmonar com manifestação clínico-radiológica semelhante à tuberculose. Estão associados fatores de risco: bronquiectasias, doença pulmonar obstrutiva crônica, seqüela de tuberculose, pneumoconiose e imunossupressão. Relata-se um caso de derrame pleural, em paciente de 67 anos, com doença pulmonar obstrutiva crônica e antecedente de tuberculose. O diagnóstico de tuberculose pleuropulmonar foi sugerido pelo exame anatomopatológico de pleura, que demonstrou processo crônico granulomatoso e presença de bacilo álcool-ácido resistente. Nas culturas de líquido e tecido pleurais foi detectado Mycobacterium kansasii. Discute-se o diagnóstico diferencial com outros agentes infecciosos na doença granulomatosa pleural e tratamento.