Comparison of methods for the isolation of mycobacteria from water treatment plant sludge

Isolation and identification of nontuberculous mycobacteria from raw milk and traditional cheese based on the 16S rRNA and hsp65 genes, Tehran, Iran

As an important source of human food, milk can be a carrier of human pathogenic bacteria, including tuberculous and nontuberculous mycobacteria (NTM), in its raw and unpasteurized state. In this research, 175 raw milk samples and 175 traditional cheese samples were collected from traditional dairy stores in 22 regions of Tehran in a 9- month period from August 2019 to May 2020. Samples were prepared and transferred to a specialized laboratory, where they were inoculated in Lowenstein-Jensen (LJ) medium containing glycerol or sodium pyruvate, as well as Herrold's egg-yolk with and without Mycobactin J. to determine the sample's identity of samples. The recommended 16S rRNA (1436 bp) and hsp65 (644 bp) gene fragments from the positive isolates identified in Ziehl-Neelsen (Z-N) staining were amplified and sequenced using PCR and compared with the sequences of the gene fragments of reference strains available in the global GenBank database. No mycobacterial species were isolated from traditional cheese samples in microbial culture. In case of raw milk samples, a total of four bacteria were collected, all of which were found in the genetic differential testing to be NTM, including n = 1 Mycobacterium heraklionense, n = 2 Mycolicibacterium fortuitum, and n = 1 Mycobacterium thermoresistibile. The analysis of the results obtained by isolate sequencing using the 16S rRNA gene showed higher discriminatory power and percentage similarities in the identification of the isolates than the hsp65 gene.

Description of new species of Mycobacterium terrae complex isolated from sewage at the São Paulo zoological park foundation in Brazil

Five mycobacterial isolates from sewage were classified as members of the genus Mycobacterium but presented inconclusive species assignments. Thus, the isolates (MYC017, MYC098, MYC101, MYC123 and MYC340) were analyzed by phenotypical, biochemical, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and genomic features to clarify their taxonomic position. Phenotypic analysis and biochemical tests did not distinguish these isolates from other non-pigmented mycobacteria. In contrast, MALDI-TOF MS analysis showed that isolates were not related to any previously described Mycobacterium species. Comparative genomic analysis showed values of ANI and dDDH between 81.59-85.56% and 24.4-28.8%, respectively, when compared to the genomes of species of this genus. In addition, two (MYC101 and MYC123) presented indistinguishable protein spectra from each other and values of ANI = 98.57% and dDDH = 97.3%, therefore being considered as belonging to the same species. Phylogenetic analysis grouped the five isolates within the Mycobacterium terrae complex (MTC) but in a specific subclade and separated from the species already described and supported by 100% bootstrap value, confirming that they are part of this complex but different from earlier described species. According to these data, we propose the description of four new species belonging to the Mycobacterium genus: (i) Mycobacterium defluvii sp. nov. strain MYC017T (= ATCC TSD-296T = JCM 35364T), (ii) Mycobacterium crassicus sp. nov. strain MYC098T (= ATCC TSD-297T = JCM 35365T), (iii) Mycobacterium zoologicum sp. nov. strain MYC101T (= ATCC TSD-298T = JCM 35366T) and MYC123 (= ATCC BAA-3216 = JCM 35367); and (iv) Mycobacterium nativiensis sp. nov. strain MYC340T (= ATCC TSD-299T = JCM 35368T).

Comparison of Actinobacteria communities from human‐impacted and pristine karst caves

Actinobacteria are important cave inhabitants, but knowledge of how anthropization and anthropization‐related visual marks affect this community on cave walls is lacking. We compared Actinobacteria communities among four French limestone caves (Mouflon, Reille, Rouffignac, and Lascaux) ranging from pristine to anthropized, and within Lascaux Cave between marked (wall visual marks) and unmarked areas in different rooms (Sas‐1, Passage, Apse, and Diaclase). In addition to the 16S rRNA gene marker, 441 bp fragments of the hsp65 gene were used and an hsp65‐related taxonomic database was constructed for the identification of Actinobacteria to the species level by Illumina‐MiSeq analysis. The hsp65 marker revealed higher resolution for species and higher richness (99% operational taxonomic units cutoff) versus the 16S rRNA gene; however, more taxa were identified at higher taxonomic ranks. Actinobacteria communities varied between Mouflon and Reille caves (both pristine), and Rouffignac and Lascaux (both anthropized). Rouffignac displayed high diversity of Nocardia, suggesting human inputs, and Lascaux exhibited high Mycobacterium relative abundance, whereas Gaiellales were typical in pristine caves and the Diaclase (least affected area of Lascaux Cave). Within Lascaux, Pseudonocardiaceae dominated on unmarked walls and Streptomycetaceae (especially Streptomyces mirabilis) on marked walls, indicating a possible role in mark formation. A new taxonomic database  was developed. Although not all Actinobacteria species were represented, the use of the hsp65 marker enabled species‐level variations of the Actinobacteria community to be documented based on the extent of anthropogenic pressure. This approach proved effective when comparing different limestone caves or specific conditions within one cave.

One health pathogen surveillance demonstrated the dissemination of gut pathogens within the two coastal regions associated with intensive farming

BACKGROUND

Intensive aquaculture farming has caused significant degradation of coastal wetlands and has been proposed as a reservoir for pathogenic Vibrio spp.

RESULTS

Gut pathogens including Vibrio spp., Salmonella spp., and Klebsiella spp. were isolated from bird feces, shrimp and wetland water in two typical coastal regions of China in 2015 and 2017 and were subsequently subjected to whole-genome sequencing. Meanwhile, local patient isolates were also selected to confirm the epidemiological links. Bacterial community composition analyses of the sediments that were sampled in 2015 and 2017 were conducted by the hypervariable region 4 of the 16S rRNA gene. Together with the local clinical isolates, we observed highly related Vibrio isolates from waterbirds, wetlands and shrimp. Phylogenetic genome comparisons also demonstrated that sequence types ST3 and ST2414 Vibrio parahaemolyticus isolates obtained from aquatic animals were clonally related to patient isolates. Likewise, three Salmonella typhimurium isolates were also genomically related to one clinical strain. The results showed that farming activities significantly altered the community composition and resulted in the emergence of several pathogens, including Acinetobacter, Mycobacterium and Legionella.

CONCLUSIONS

In conclusion, our results demonstrated that intensive shrimp farming in wetlands has two devastating impacts: pathogen dissemination from aquatic animals into migratory birds and transmission of foodborne pathogens into local communities.

Genomic and temporal analyses of Mycobacterium bovis in southern Brazil

Mycobacterium bovis is a causal agent of bovine tuberculosis (bTB), one of the most important diseases currently facing the cattle industry worldwide. Tracing the source of M. bovis infections of livestock is an important tool for understanding the epidemiology of bTB and defining control/eradication strategies. In this study, whole genome sequencing (WGS) of 74 M. bovis isolates sourced from naturally infected cattle in the State of Rio Grande do Sul (RS), southern Brazil, was used to evaluate the population structure of M. bovis in the region, identify potential transmission events and date the introduction of clonal complex (CC) European 2 (Eu2). In silico spoligotyping identified 11 distinct patterns including four new profiles and two CCs, European 1 (Eu1) and Eu2. The analyses revealed a high level of genetic diversity in the majority of herds and identified putative transmission clusters that suggested that within- and between-herd transmission is occurring in RS. In addition, a comparison with other published M. bovis isolates from Argentina, Brazil, Paraguay and Uruguay demonstrated some evidence for a possible cross-border transmission of CC Eu1 into RS from Uruguay or Argentina. An estimated date for the introduction of CC Eu2 into RS in the middle of the 19th century correlated with the historical introduction of cattle into RS to improve existing local breeds. These findings contribute to the understanding of the population structure of M. bovis in southern Brazil and highlight the potential of WGS in surveillance and helping to identify bTB transmission.

Diversity of Mycobacteriaceae from aquatic environment at the São Paulo Zoological Park Foundation in Brazil

We investigated the species diversity of Mycobacteriaceae in surface water samples from six environments at the zoological park in São Paulo, Brazil. Three hundred and eighty isolates were cultivated and identified by phenotypic characteristics (growth rate and pigmentation) and sequencing of hsp65, rpoB and 16S rRNA genes. The results revealed that almost 48% of the isolates could be identified at the species level; about 50% were classified at the genus level, and only less than 2% of the isolates showed an inconclusive identification. The isolates classified at the genus level and not identified were then evaluated by phylogenetic analyses using the same three concatenated target genes. The results allowed us to identify at the genus level some isolates that previously had inconclusive identification, and they also suggested the presence of putative candidate species within the sample, demonstrating that this zoological park is an important source of diversity.

Matrix Assisted Laser Desorption Ionization-Time-of-Flight mass spectrometry identification of Mycobacterium bovis in Bovinae

In this study, Matrix Assisted Laser Desorption Ionization-Time-of-Flight (MALDI-TOF) mass spectrometry was used to identify Mycobacterium bovis from cattle and buffalo tissue isolates from the North and South regions of Brazil, grown in solid medium and previously identified by Polymerase Chain Reaction (PCR) based on Region of Difference 4 (RD4), sequencing and spoligotyping. For this purpose, the protein extraction protocol and the mass spectra reference database were optimized for the identification of 80 clinical isolates of mycobacteria. As a result of this optimization, it was possible to identify and differentiate M. bovis from other members of the Mycobacterium tuberculosis complex with 100% specificity, 90.91% sensitivity and 91.25% reliability. MALDI-TOF MS methodology described herein provides successful identification of M. bovis within bovine/bubaline clinical samples, demonstrating its usefulness for bovine tuberculosis diagnosis in the future.

Recovery of Non-tuberculous Mycobacteria from Water is Influenced by Phenotypic Characteristics and Decontamination Methods

Infections related to non-tuberculous mycobacteria (NTM) have recently increased worldwide. The transmission of these microorganisms from the environment has been suggested as the main source for human infections. To elucidate the epidemiological aspects and distribution of these pathogens, many studies have evaluated several decontamination methods and protocols to properly isolate NTM from environmental samples, mainly from water. However, no satisfactory strategy has been found for isolation of most of the NTM species harboring different phenotypic characteristics. Here, we evaluated the susceptibility of 23 NTM strains presenting variable growth rate and pigmentation patterns to eight different methods: oxalic acid (2.5% and 5%), cetylpyridinium chloride (CPC) (0.0025% and 0.005%), sodium hydroxide (NaOH) (2% and 4%), and sodium dodecyl sulfate (SDS) plus NaOH (SDS 1.5%-NaOH 0.5% and SDS 3%-NaOH 1%). It was found that the viability of NTM exposed to different decontamination methods varies according to their phenotypic characteristics and two methods (SDS 1.5% plus NaOH 0.5% and CPC 0.0025%) were necessary for effective isolation of all of the species tested. These findings supply important insights for future studies on the environmental occurrence of mycobacteria and improving the sensibility of traditional strategies.

Global Environmental Nontuberculous Mycobacteria and Their Contemporaneous Man-Made and Natural Niches

Seminal microbiological work of environmental nontuberculous mycobacteria (NTM) includes the discovery that NTM inhabit water distribution systems and soil, and that the species of NTM found are geographically diverse. It is likely that patients acquire their infections from repeated exposures to their environments, based on the well-accepted paradigm that water and soil bioaerosols - enriched for NTM - can be inhaled into the lungs. Support comes from reports demonstrating NTM isolated from the lungs of patients are genetically identical to NTM found in their environment. Well documented sources of NTM include peat-rich soils, natural waters, drinking water, hot water heaters, refrigerator taps, catheters, and environmental amoeba. However, NTM have also been recovered in biofilms from ice machines, heated nebulizers, and heater-cooler units, as well as seat dust from theaters, vacuum cleaners, and cobwebs. New studies on the horizon aim to significantly expand the current knowledge of environmental NTM niches in order to improve our current understanding of the specific ecological factors driving the emergence of NTM lung disease. Specifically, the Hawaiian Island environment is currently being studied as a model to identify other point sources of exposure as it is the U.S. state with the highest number of NTM lung disease cases. Because of its geographic isolation and unique ecosystem, the Hawaiian environment is being probed for correlative factors that may promote environmental NTM colonization.

Mycobacterium heraklionense sp. nov.: A case series

Mycobacterium heraklionense sp. nov. (M. heraklionense) is a novel non-tuberculous mycobacterium belonging to the Mycobacterium terrae complex that has recently been described. It has a world-wide distribution. Recently, a case of tenosynovitis in an immunocompetent individual caused by M. heraklionense was reported, indicating that it has the ability to cause diseases. In the present study, in order to provide a more detailed profile of this mycobacterium and to obtain a more complete overall picture of its clinical significance, we report all available data regarding the initial 12 cases of its isolation. Of the 12 patients, 5 (42%) eventually died within a period of 3 months following the isolation of the mycobacterium. However, any connection between the presence of M. heraklionense and these deaths could not be documented. These 5 patients were all males with a mean age of 74.6 years suffering from serious underlying diseases, which most probably were the cause of death. Additional data from possible new cases of M. heraklionense isolation are anticipated.

Draft Genome Sequence of Mycobacterium heraklionense Strain Davo

We report the draft genome sequence of Mycobacterium heraklionense strain Davo, isolated from a fine-needle aspirate of a right-ankle soft-tissue mass. This is the first draft genome sequence of Mycobacterium heraklionense, a nonpigmented rapidly growing mycobacterium.