Large-restriction-fragment polymorphism analysis of Mycobacterium chelonae and Mycobacterium terrae isolates

Non-tuberculous mycobacteria: a disease beyond TB and preparedness in India

BACKGROUND AND METHODS

Fifty-six Indian studies on NTM diseases were selected between 1981 and 2020 from various electronic databases (PubMed, EMBASE, Medline, BIOSIS preview, and Scopus) for systematic review.

RESULTS

NTM isolation rates increased from 0.9% between 2001 and 2010 to 1.6% between 2011 and 2020. Prevalence of NTM-pulmonary disease (NTM-PD) among presumptive-TB patients in India was 1.1% (395/34,829). M. avium complex (MAC) (19%) was most commonly isolated from pulmonary specimens followed by M. chelonae (10%), M. fortuitum (9.8%), and M. abscessus (8.8%). M. fortuitum (35.5%), M. chelonae (23.6%) and M. abscessus (15%) were frequently reported from extra-pulmonary specimens. Patients with NTM-PD were mostly treated with a macrolide-based three-drug regimen. Clarithromycin-based-drug regimen in combination with amikacin, ciprofloxacin and several other drugs (rifampicin, imipenem, ofloxacin, linezolid, azithromycin) was used for treatment of EP-NTM. Median duration of the treatment in NTM-PD was 12 months, (6-18 months) whereas it was 6 months (3.1-8.7 months) in EP-NTM. Treatment was successful in 45% (19/42) of NTM-PD patients and 75% (93/124) of EP-NTM patients.

CONCLUSION

It is concluded from this review that most Indian studies have published laboratory data on NTM isolation and speciation and lacked information on clinical, microbiological and radiological correlation and treatment outcome details. Future studies should address these issues while publishing on NTM diseases.

Mycobacteriosis in zebrafish colonies

Mycobacteriosis, a chronic bacterial infection, has been associated with severe losses in some zebrafish facilities and low-level mortalities and unknown impacts in others. The occurrence of at least six different described species (Mycobacterium abscessus, M. chelonae, M. fortuitum, M. haemophilum, M. marinum, M. peregrinum) from zebrafish complicates diagnosis and control because each species is unique. As a generalization, mycobacteria are often considered opportunists, but M. haemophilum and M. marinum appear to be more virulent. Background genetics of zebrafish and environmental conditions influence the susceptibility of fish and progression of disease, emphasizing the importance of regular monitoring and good husbandry practices. A combined approach to diagnostics is ultimately the most informative, with histology as a first-level screen, polymerase chain reaction for rapid detection and species identification, and culture for strain differentiation. Occurrence of identical strains of Mycobacterium in both fish and biofilms in zebrafish systems suggests transmission can occur when fish feed on infected tissues or tank detritus containing mycobacteria. Within a facility, good husbandry practices and sentinel programs are essential for minimizing the impacts of mycobacteria. In addition, quarantine and screening of animals coming into a facility is important for eliminating the introduction of the more severe pathogens. Elimination of mycobacteria from an aquatic system is likely not feasible because these species readily establish biofilms on surfaces even in extremely low nutrient conditions. Risks associated with each commonly encountered species need to be identified and informed management plans developed. Basic research on the growth characteristics, disinfection, and pathogenesis of zebrafish mycobacteria is critical moving forward.

Outbreak of Mycobacterium chelonae infection associated with tattoo ink

BACKGROUND

In January 2012, on the basis of an initial report from a dermatologist, we began to investigate an outbreak of tattoo-associated Mycobacterium chelonae skin and soft-tissue infections in Rochester, New York. The main goals were to identify the extent, cause, and form of transmission of the outbreak and to prevent further cases of infection.

METHODS

We analyzed data from structured interviews with the patients, histopathological testing of skin-biopsy specimens, acid-fast bacilli smears, and microbial cultures and antimicrobial susceptibility testing. We also performed DNA sequencing, pulsed-field gel electrophoresis (PFGE), cultures of the ink and ingredients used in the preparation and packaging of the ink, assessment of source water and faucets at tattoo parlors, and investigation of the ink manufacturer.

RESULTS

Between October and December 2011, a persistent, raised, erythematous rash in the tattoo area developed in 19 persons (13 men and 6 women) within 3 weeks after they received a tattoo from a single artist who used premixed gray ink; the highest occurrence of tattooing and rash onset was in November (accounting for 15 and 12 patients, respectively). The average age of the patients was 35 years (range, 18 to 48). Skin-biopsy specimens, obtained from 17 patients, showed abnormalities in all 17, with M. chelonae isolated from 14 and confirmed by means of DNA sequencing. PFGE analysis showed indistinguishable patterns in 11 clinical isolates and one of three unopened bottles of premixed ink. Eighteen of the 19 patients were treated with appropriate antibiotics, and their condition improved.

CONCLUSIONS

The premixed ink was the common source of infection in this outbreak. These findings led to a recall by the manufacturer.

Outbreak of nontuberculous mycobacterial subcutaneous infections related to multiple mesotherapy injections

We describe an outbreak of severe subcutaneous infections due to nontuberculous mycobacteria following mesotherapy. Epidemiological studies and molecular comparisons of Mycobacterium chelonae strains from different patients and the environment suggested that contamination may be associated with inappropriate cleaning of the multiple-injection device with tap water.

Distribution and genetic characterization of Mycobacterium chelonae in laboratory zebrafish Danio rerio

During routine screening of zebrafish at a research facility, histological changes consistent with mycobacteriosis were observed, prompting an investigation to determine the background prevalence and distribution of Mycobacterium species throughout the facility. Infection status was evaluated in 240 zebrafish representing 9 genetic lines, using histology, culture and PCR. Environmental sources were also tested for the presence of mycobacteria. Prevalence in zebrafish by culture and PCR was 10% (24/240), 21 of which were TU line fish. All isolates from fish were identified as M. chelonae by hsp65 DNA sequencing; subsequent DNA fingerprinting delineated 3 strains, designated H1E1 (1/24), H1E2 (22/24), and H1E3 (1/24). From external sources, tank or tubing surface biofilms were positive by culture (13/32) with multiple species and strains isolated including M. neoaurum, M. phocaicum, and identical strains of M. chelonae that were found in zebrafish: H1E1 (2/13) and H1E2 (8/13). Comparing diagnostic methods, acid-fast stained histological sections showed substantial agreement with plate culture and PCR for detection of mycobacteria in fish. Observation of granulomas in hematoxylin and eosin-stained sections was a less reliable predictor of mycobacteriosis, as uninfected females with egg-associated inflammation and hyperplasia were misdiagnosed. These data revealed background levels of mycobacteriosis in a healthy and well-managed facility. Infected populations were removed, although the apparent ability for M. chelonae to remain viable in environmental reservoirs may make it difficult to eradicate completely. This highlights the importance of an animal-health monitoring program and good husbandry practices to prevent disease in zebrafish research laboratories.

Assessment of DNA damage and repair in Mycobacterium terrae after exposure to UV irradiation

AIM

Ultraviolet (UV) irradiation for drinking water treatment was examined for inactivation and subsequent dark and photo-repair of Mycobacterium terrae.

METHODS AND RESULTS

UV sources tested were low pressure (monochromatic, 254 nm) and medium pressure (polychromatic UV output) Hg lamps. UV exposure resulted in inactivation, and was followed by dark or photo-repair experiments. Inactivation and repair were quantified utilizing a molecular-based endonuclease sensitive site (ESS) assay and conventional colony forming unit (CFU) viability assay. Mycobacterium terrae was more resistant to UV disinfection compared to many other bacteria, with approximately 2-log reduction at a UV fluence of 10 mJ cm(-2) ; similar to UV inactivation of M. tuberculosis. There was no difference in inactivation between monochromatic or polychromatic UV lamps. Mycobacterium terrae did not undergo detectable dark repair. Photo-repair resulted in recovery from inactivation by approximately 0.5-log in less than 30 min for both UV lamp systems.

CONCLUSIONS

Mycobacterium terrae is able to photo-repair DNA damage within a short timeframe. The number of pyrimidine dimers induced by UV light were similar for Escherichia coli and M. terrae, however, this similarity did not hold true for viability results.

SIGNIFICANCE AND IMPACT OF THE STUDY

There is no practical difference between UV sources for disinfection or prevention of DNA repair for M. terrae. The capability of M. terrae to photo-repair UV damage fairly quickly is important for wastewater treatment applications where disinfected effluent is exposed to sunlight. Finally, molecular based assay results should be evaluated with respect to differences in the nucleic acid content of the test micro-organism.

Occurrence and characterization of multiple novel genotypes of Mycobacterium immunogenum and Mycobacterium chelonae in metalworking fluids

Rapidly growing mycobacteria colonize metalworking fluids, leading to contamination of occupational environments and exposure-related respiratory illnesses in machine workers. Lately, it has been emphasized that these fluids are colonizable by a single genotype of a rapidly growing mycobacterium species, Mycobacterium immunogenum. Here, we report on the genotypic diversity of mycobacteria in these fluids, including isolation and characterization of multiple novel genotypes of two distinct species, Mycobacterium chelonae and M. immunogenum. Using agar culturing and Mycobacterium-specific PCR, 13 mycobacterial isolates were recovered from 100 geographically diverse in-use metalworking fluid samples. Based on restriction fragment length polymorphism of PCR products, DNA sequencing (hsp65 gene segment), and phylogenetic analysis of 16S-23S rDNA internal transcribed spacer (ITS) sequences, six isolates were identified as M. immunogenum and seven as M. chelonae; an additional isolate from metalworking fluid diluent water was identified as M. diernhoferi. Genomic DNA macro-restriction fragment pattern analysis, using pulsed-field gel electrophoresis with XbaI and SpeI restriction digestions, showed intraspecies variation among the isolates of M. immunogenum and M. chelonae. Visual and computer-assisted dendrogram analysis of the XbaI macro-restriction patterns revealed three novel genotypes of M. immunogenum and two of M. chelonae, whereas SpeI macro-restriction patterns revealed only two genotypes for each isolate. None of the identified genotypes matched the reportedly dominant one of M. immunogenum from metalworking fluids. Both mycobacterial species are prevalent in metalworking fluids and there is a considerable strain-level genetic diversity within them.

Genetic diversity of Mycobacterium avium subspecies paratuberculosis isolates from goats detected by pulsed-field gel electrophoresis

Paratuberculosis in goats occurs worldwide causing considerable economic losses mainly due to reduced milk production. Nowadays, there is still relatively little knowledge about the epidemiology of this disease in goats, and only a few epidemiological studies have been carried out in goats naturally infected with Mycobacterium avium subspecies paratuberculosis (M. a. paratuberculosis). The objective of this study was to characterize forty four clinical caprine isolates of M. a. paratuberculosis by different molecular techniques (pulsed-field gel electrophoresis [PFGE], restriction fragment length polymorphism analysis coupled with hybridization to IS900, and IS1311 polymerase chain reaction-restriction enzyme analysis) to determine the most useful technique for molecular typing of caprine isolates, as well as to disclose the genetic variation amongst caprine isolates and the relationship with strains isolated from other animal species. PFGE was found to be the most discriminative technique identifying a total of 13 'multiplex' PFGE profiles, ten of which were novel profiles found only in caprine isolates to date. All isolates were genotyped as Type II strains, except two isolates that resembled the intermediate group referred as Type III.