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Bacteria in general interact with zooplankton in aquatic ecosystems. These zooplankton-bacterial interactions help to shape the bacterial community by regulating bacterial abundances. Such interactions are even more significant and crucially in need of investigation in the case of pathogenic bacteria, which cause severe diseases in humans and animals. Among the many associations between a host metazoan and pathogenic bacteria, zooplankton provide nutrition and protection from stressful conditions, promote the horizontal transfer of virulence genes, and act as a mode of pathogen transport. These interactions allow the pathogen to survive and proliferate in aquatic environments and to endure water treatment processes, thereby creating a potential risk to human health. This review highlights current knowledge on the contributions of zooplankton to the survival and pathogenicity of pathogenic bacteria. We also discuss the need to consider these interactions as a risk factor in water treatment processes.
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Ecossistema , Zooplâncton , Animais , Humanos , BactériasRESUMO
Delamanid (DLM), a nitro-dihydroimidazooxazole derivative currently approved for pulmonary multidrug-resistant tuberculosis (TB) therapy, is a prodrug activated by mycobacterial 7,8-didemethyl-8-hydroxy 5-deazaflavin electron transfer coenzyme (F420)-dependent nitroreductase (Ddn). Despite inhibiting the biosynthesis of a subclass of mycolic acids, the active DLM metabolite remained unknown. Comparative liquid chromatography-mass spectrometry (LC-MS) analysis of DLM metabolites revealed covalent binding of reduced DLM with a nicotinamide ring of NAD derivatives (oxidized form) in DLM-treated Mycobacterium tuberculosis var. Bacille de Calmette et Guérin. Isoniazid-resistant mutations in the type II NADH dehydrogenase gene (ndh) showed a higher intracellular NADH/NAD ratio and cross-resistance to DLM, which were restored by complementation of the mutants with wild-type ndh Our data demonstrated for the first time the adduct formation of reduced DLM with NAD in mycobacterial cells and its importance in the action of DLM.
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Antituberculosos/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/genética , Nitroimidazóis/farmacologia , Oxazóis/farmacologia , Tuberculose Resistente a Múltiplos Medicamentos/genética , Tuberculose Pulmonar/tratamento farmacológico , Cromatografia Líquida , Farmacorresistência Bacteriana Múltipla/genética , Isoniazida/farmacologia , Espectrometria de Massas , Ácidos Micólicos/metabolismo , NAD/análise , NADH Desidrogenase/genética , Oxirredução , Polimorfismo de Nucleotídeo Único/genética , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológicoRESUMO
We previously demonstrated the colonization of Mycobacterium avium complex in bathrooms by the conventional culture method. In the present study, we aimed to directly detect M. avium organisms in the environment using loop-mediated isothermal amplification (LAMP), and to demonstrate the efficacy of LAMP by comparing the results with those obtained by culture. Our data showed that LAMP analysis has detection limits of 100 fg DNA/reaction for M. avium. Using an FTA(®) elute card, DNA templates were extracted from environmental samples from bathrooms in the residences of 29 patients with pulmonary M. avium disease. Of the 162 environmental samples examined, 143 (88%) showed identical results by both methods; 20 (12%) and 123 (76%) samples were positive and negative, respectively, for M. avium. Of the remaining 19 samples (12%), seven (5%) and 12 (7%) samples were positive by the LAMP and culture methods, respectively. All samples that contained over 20 colony forming units/primary isolation plate, as measured by the culture method, were also positive by the LAMP method. Our data demonstrate that the combination of the FTA elute card and LAMP can facilitate prompt detection of M. avium in the environment.
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Monitoramento Ambiental/métodos , Complexo Mycobacterium avium/isolamento & purificação , Técnicas de Amplificação de Ácido Nucleico/métodos , Quartos de Pacientes , Microbiologia da Água , Humanos , Japão , Complexo Mycobacterium avium/genética , Complexo Mycobacterium avium/crescimento & desenvolvimento , Infecção por Mycobacterium avium-intracellulare/microbiologia , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/metabolismo , Sensibilidade e EspecificidadeRESUMO
Bioaerosols play essential roles in the atmospheric environment and can affect human health. With a few exceptions (e.g., farm or rainforest environments), bioaerosol samples from wide-ranging environments typically have a low biomass, including bioaerosols from indoor environments (e.g., residential homes, offices, or hospitals), outdoor environments (e.g., urban or rural air). Some specialized environments (e.g., clean rooms, the Earth's upper atmosphere, or the international space station) have an ultra-low-biomass. This review discusses the primary sources of bioaerosols and influencing factors, the recent advances in air sampling techniques and the new generation sequencing (NGS) methods used for the characterization of low-biomass bioaerosol communities, and challenges in terms of the bias introduced by different air samplers when samples are subjected to NGS analysis with a focus on ultra-low biomass. High-volume filter-based or liquid-based air samplers compatible with NGS analysis are required to improve the bioaerosol detection limits for microorganisms. A thorough understanding of the performance and outcomes of bioaerosol sampling using NGS methods and a robust protocol for aerosol sample treatment for NGS analysis are needed. Advances in NGS techniques and bioinformatic tools will contribute toward the precise high-throughput identification of the taxonomic profiles of bioaerosol communities and the determination of their functional and ecological attributes in the atmospheric environment. In particular, long-read amplicon sequencing, viability PCR, and meta-transcriptomics are promising techniques for discriminating and detecting pathogenic microorganisms that may be active and infectious in bioaerosols and, therefore, pose a threat to human health. Supplementary Information: The online version contains supplementary material available at 10.1007/s41745-023-00380-x.
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Currently, tuberculosis (TB) in Japan is highly prevalent among elderly patients who were born during a time when TB was highly prevalent. Mycobacterium tuberculosis (Mtb) lineage 2 (L2) is the predominant strain in the country. Moreover, the proportion of foreign-born patients with TB has been increasing. This epidemiological situation in Japan motivated us to explore the heterogeneity in transmission dynamics among the sublineages of Mtb L2 within this aging population. For this purpose, we conducted a population-based whole genome sequencing analysis of 550 Mtb strains in Kobe, Japan, and employed pairwise single nucleotide polymorphism (SNP) distance clustering and terminal branch length (TBL) distribution analysis to assess Mtb transmission. The genomic clustering rate with a threshold of ≤5 SNPs was significantly lower in elderly patients aged 70 years or higher than in non-elderly patients. The elderly patient group showed significantly longer TBL than the non-elderly group. These results supported the notion that reactivation of distant infection is a major driving force for the high incidence of TB in elderly individuals. The age group distribution and frequency of lineages/sublineages were found to significantly differ between foreign-born and Japan-born patients. The increased proportion of foreign-born patients might have resulted in more strain diversity in Japan. The L2.2.A sublineage demonstrated a significant association with elderly patients and exhibited lower transmission rates, which indicate to be prone to reactivate from long-term latency. In contrast, L2.2.Modern, showed a strong association with younger and foreign-born patients. This sublineage showed a high genomic cluster rate, suggesting its high transmissibility. The other three major sublineages, namely L2.2.AA2, L2.2.AA3.1, and L2.2.AA3.2, exhibited a consistent increase in cluster rates across varying SNP thresholds, indicating their relatively recent emergence as endemic sublineages in Japan. In conclusion, this study highlights distinct differences in the transmission dynamics of L2 sublineages within an aging society.
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Mycobacterium tuberculosis , Tuberculose , Idoso , Humanos , Pessoa de Meia-Idade , Mycobacterium tuberculosis/genética , Japão/epidemiologia , Genótipo , Tuberculose/epidemiologia , Tuberculose/microbiologia , Epidemiologia MolecularRESUMO
Survival of the live attenuated Bacillus Calmette-Guérin (BCG) vaccine amidst harsh host environments is key for BCG effectiveness as it allows continuous immune response induction and protection against tuberculosis. Mycobacterial DNA binding protein 1 (MDP1), a nucleoid associated protein, is essential in BCG. However, there is limited knowledge on the extent of MDP1 gene regulation and how this influences BCG survival. Here, we demonstrate that MDP1 conditional knockdown (cKD) BCG grows slower than vector control in vitro, and dies faster upon exposure to antibiotics (bedaquiline) and oxidative stress (H2O2 and menadione). MDP1-cKD BCG also exhibited low infectivity and survival in THP-1 macrophages and mice indicating possible susceptibility to host mediated stress. Consequently, low in vivo survival resulted in reduced cytokine (IFN-gamma and TNF-alpha) production by splenocytes. Temporal transcriptome profiling showed more upregulated (81-240) than downregulated (5-175) genes in response to MDP1 suppression. Pathway analysis showed suppression of biosynthetic pathways that coincide with low in vitro growth. Notable was the deferential expression of genes involved in stress response (sigI), maintenance of DNA integrity (mutT1), REDOX balance (WhiB3), and host interactions (PE/PE_PGRS). Thus, this study shows MDP1's importance in BCG survival and highlights MDP1-dependent gene regulation suggesting its role in growth and stress adaptation.
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Vacina BCG , Insuficiência Renal Crônica , Animais , Camundongos , Peróxido de Hidrogênio , Proteínas de Ligação a DNA/genética , AclimataçãoRESUMO
Mycobacterium avium, a member of the M. avium complex (MAC), is the major pathogen contributing to nontuberculous mycobacteria (NTM) infections worldwide. Fluoroquinolones (FQs) are recommended for the treatment of macrolide-resistant MACs. The association of FQ resistance and mutations in the quinolone resistance-determining region (QRDR) of gyrA of M. avium is not yet clearly understood, as many FQ-resistant clinical M. avium isolates do not have such mutations. This study aimed to elucidate the role of amino acid substitution in the QRDR of M. avium GyrA in the development of FQ resistance. We found four clinical M. avium subsp. hominissuis isolates with Asp-to-Gly change at position 95 (Asp95Gly) and Asp95Tyr mutations in gyrA that were highly resistant to FQs and had 2- to 32-fold-higher MICs than the wild-type (WT) isolates. To clarify the contribution of amino acid substitutions to FQ resistance, we produced recombinant WT GyrA, GyrB, and four GyrA mutant proteins (Ala91Val, Asp95Ala, Asp95Gly, and Asp95Tyr) to elucidate their potential role in FQ resistance, using them to perform FQ-inhibited DNA supercoiling assays. While all the mutant GyrAs contributed to the higher (1.3- to 35.6-fold) FQ 50% inhibitory concentration (IC50) than the WT, Asp95Tyr was the most resistant mutant, with an IC50 15- to 35.6-higher than that of the WT, followed by the Asp95Gly mutant, with an IC50 12.5- to 17.6-fold higher than that of the WT, indicating that these amino acid substitutions significantly reduced the inhibitory activity of FQs. Our results showed that amino acid substitutions in the gyrA of M. avium contribute to FQ resistance. IMPORTANCE The emergence of fluoroquinolone (FQ) resistance has further compounded the control of emerging Mycobacterium avium-associated nontuberculous mycobacteria infections worldwide. For M. avium, the association of FQ resistance and mutations in the quinolone resistance-determining region (QRDR) of gyrA is not yet clearly understood. Here, we report that four clinical M. avium isolates with a mutation in the QRDR of gyrA were highly resistant to FQs. We further clarified the impact of mutations in the QRDR of GyrA proteins by performing in vitro FQ-inhibited DNA supercoiling assays. These results confirmed that, like in Mycobacterium tuberculosis, mutations in the QRDR of gyrA also strongly contribute to FQ resistance in M. avium. Since many FQ-resistant M. avium isolates do have these mutations, the detailed molecular mechanism of FQ resistance in M. avium needs further exploration.
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Fluoroquinolonas , Mycobacterium tuberculosis , Fluoroquinolonas/farmacologia , Substituição de Aminoácidos , DNA Girase/genética , DNA Girase/metabolismo , Mycobacterium avium/genética , Antibacterianos/farmacologia , Mutação , Mycobacterium tuberculosis/metabolismo , Testes de Sensibilidade Microbiana , Farmacorresistência Bacteriana/genéticaRESUMO
Mycobacterium avium subsp. hominissuis (MAH) is one of the most prevalent mycobacteria causing non-tuberculous mycobacterial disease in humans and animals. Of note, MAH is a major cause of mycobacterial granulomatous mesenteric lymphadenitis outbreaks in pig populations. To determine the precise source of infection of MAH in a pig farm and to clarify the epidemiological relationship among pig, human and environmental MAH lineages, we collected 50 MAH isolates from pigs reared in Japan and determined draft genome sequences of 30 isolates. A variable number of tandem repeat analysis revealed that most pig MAH isolates in Japan were closely related to North American, European and Russian human isolates but not to those from East Asian human and their residential environments. Historical recombination analysis revealed that most pig isolates could be classified into SC2/4 and SC3, which contain MAH isolated from pig, European human and environmental isolates. Half of the isolates in SC2/4 had many recombination events with MAH lineages isolated from humans in East Asia. To our surprise, four isolates belonged to a new lineage (SC5) in the global MAH population. Members of SC5 had few footprints of inter-lineage recombination in the genome, and carried 80 unique genes, most of which were located on lineage specific-genomic islands. Using unique genetic features, we were able to trace the putative transmission route via their host pigs. Together, we clarify the possibility of species-specificity of MAH in addition to local adaptation. Our results highlight two transmission routes of MAH, one exposure on pig farms from the environment and the other via pig movement. Moreover, our study also warns that the evolution of MAH in pigs is influenced by MAH from patients and their residential environments, even if the MAH are genetically distinct.
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We report herein the draft genome sequence of Mycobacterium intracellulare clinical strain M.i.198, which consistently exhibits hypervirulence in human patients, human macrophages in vitro, and immunocompetent mice.
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Genoma Bacteriano , Complexo Mycobacterium avium/classificação , Complexo Mycobacterium avium/genética , Infecção por Mycobacterium avium-intracellulare/microbiologia , Animais , Células Cultivadas , Humanos , Imunocompetência , Macrófagos/microbiologia , Camundongos , Dados de Sequência Molecular , Complexo Mycobacterium avium/patogenicidade , VirulênciaRESUMO
Pathogenic intracellular mycobacteria, such as Mycobacterium tuberculosis and Mycobacterium avium, which cause lung diseases, can grow in macrophages. Extracellular mycobacteria have been reported in the lungs, blood, and sputum of patients, indicating the involvement of these pathogens in disease progression. Erythrocytes are involved in the symptoms associated with pulmonary mycobacterial diseases, such as bloody sputum and hemoptysis; however, little attention has been paid to the role of erythrocytes in mycobacterial diseases. Herein, we found that Mycobacterium avium subsp. hominissuis (MAH) and Mycobacterium intracellulare colocalized with erythrocytes at the sites of lung infection, inside capillaries and necrotic areas of granulomas, using histopathological examinations. Electron microscopy showed that MAH adhered and entered human erythrocytes when they were cocultured in vitro. MAH adhered to erythrocytes through complement receptor 1 and cell-surface sialo-glycoproteins. Importantly, MAH grew vigorously without causing any pronounced damage to erythrocytes. This erythrocyte-mediated enhancement of MAH growth occurred extracellularly depending on its direct attachment to erythrocytes. In contrast, MAH failed to multiply inside erythrocytes. Similarly, erythrocytes augmented the growth of other pathogenic mycobacteria, such as M. intracellulare and M. tuberculosis. THP-1 cell-derived human macrophages preferentially phagocytosed erythrocytes that were attached to mycobacteria (compared to bacteria alone), suggesting that erythrocyte-attached mycobacteria are an efficient infectious source for macrophages. Our findings provide new insights into the pathogenesis of mycobacterial diseases and offer an alternative and useful strategy for treating mycobacterial disease. IMPORTANCE Pathogenic mycobacteria, such as Mycobacterium tuberculosis, Mycobacterium avium subsp. hominissuis (MAH), and Mycobacterium intracellulare, cause pulmonary infections as intracellular parasites of lung macrophages and epithelial cells. Here, using histopathological examinations we found that MAH and M. intracellulare colocalized with erythrocytes in lung infection sites. Subsequent studies demonstrated that direct interaction with erythrocytes enhances the extracellular proliferation of mycobacteria based on the following results: 1. MAH adhered and invaded human erythrocytes upon coculture in vitro; 2. MAH adhered to erythrocytes through complement receptor 1 and cell-surface sialo-glycoproteins; 3. MAH rapidly proliferated when directly attached to erythrocytes but not within them; 4. other mycobacteria, such as M. intracellulare and M. tuberculosis, also proliferated in the same way as MAH. The finding that pathogenic mycobacteria grow extracellularly in an erythrocyte-dependent manner is of considerable clinical importance for understanding disease progression and latent infection.
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Infecção por Mycobacterium avium-intracellulare , Mycobacterium tuberculosis , Tuberculose , Progressão da Doença , Eritrócitos , Glicoproteínas , Humanos , Mycobacterium , Complexo Mycobacterium avium , Receptores de Complemento , Tuberculose/microbiologiaRESUMO
Mycobacterium avium subsp. hominissuis (MAH) is one of the most common nontuberculous mycobacterial pathogens responsible for chronic lung disease in humans. It is widely distributed in biofilms in natural and living environments. It is considered to be transmitted from the environment. Despite its importance in public health, the ultrastructure of the MAH biofilm remains largely unknown. The ultrastructure of a MAH-containing multispecies biofilm that formed naturally in a bathtub inlet was herein reported along with those of monoculture biofilms developed from microcolonies and pellicles formed in the laboratory. Scanning electron microscopy revealed an essentially multilayered bathtub biofilm that was packed with cocci and short and long rods connected by an extracellular matrix (ECM). Scattered mycobacterium-like rod-shaped cells were observed around biofilm chunks. The MAH monoculture biofilms that developed from microcolonies in vitro exhibited an assembly of flat layers covered with thin film-like ECM membranes. Numerous small bacterial cells (0.76±0.19| |µm in length) were observed, but not embedded in ECM. A glycopeptidolipid-deficient strain did not develop the layered ECM membrane architecture, suggesting its essential role in the development of biofilms. The pellicle biofilm also consisted of flat layered cells covered with an ECM membrane and small cells. MAH alone generated a flat layered biofilm covered with an ECM membrane. This unique structure may be suitable for resistance to water flow and disinfectants and the exclusion of fast-growing competitors, and small cells in biofilms may contribute to the formation and transmission of bioaerosols.
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Biofilmes , Mycobacterium/fisiologia , Mycobacterium/ultraestrutura , Humanos , Microscopia Eletrônica de Varredura , Mycobacterium/genética , Infecções por Mycobacterium/microbiologiaRESUMO
Early detection and treatment are paramount for the timely control of Mycobacterium avium infections. Herein, we designed a LAMP assay targeting a widely used species-specific marker IS1245 for the rapid detection of M. avium and evaluated its applicability using human (n = 137) and pig (n = 91) M. avium isolates from Japan. The developed assay could detect as low as 1 genome copy of M. avium DNA within 30 minutes. All 91 (100%) M. avium isolates from pigs were detected positive while all other tested bacterial species were negative. Interestingly, among the 137 clinical M. avium isolates, 41 (30%) were undetectable with this LAMP assay as they lacked IS1245, the absence of which was revealed by PCR and whole-genome sequencing. These findings highlighted genotypic differences in M. avium strains from humans and pigs in Japan and how this diversity can influence the applicability of a detection tool across different geographic areas and hosts.
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Elementos de DNA Transponíveis/genética , Técnicas de Diagnóstico Molecular/métodos , Mycobacterium avium/genética , Técnicas de Amplificação de Ácido Nucleico/métodos , Animais , Variação Genética , Genoma Bacteriano/genética , Humanos , Japão , Infecções por Mycobacterium/microbiologia , Infecções por Mycobacterium/veterinária , Mycobacterium avium/classificação , Mycobacterium avium/isolamento & purificação , Reação em Cadeia da Polimerase , Sensibilidade e Especificidade , Especificidade da Espécie , Suínos , Doenças dos Suínos/microbiologiaRESUMO
Mycobacterium avium subsp. hominissuis (MAH) is one of the most important agents causing non-tuberculosis mycobacterial infection in humans and pigs. There have been advances in genome analysis of MAH from human isolates, but studies of isolates from pigs are limited despite its potential source of infection to human. Here, we obtained 30 draft genome sequences of MAH from pigs reared in Japan. The 30 draft genomes were 4,848,678-5,620,788 bp in length, comprising 4652-5388 coding genes and 46-75 (median: 47) tRNAs. All isolates had restriction modification-associated genes and 185-222 predicted virulence genes. Two isolates had tRNA arrays and one isolate had a clustered regularly interspaced short palindromic repeat (CRISPR) region. Our results will be useful for evaluation of the ecology of MAH by providing a foundation for genome-based epidemiological studies.
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Medical treatment of pulmonary Mycobacterium avium complex (MAC) disease does not always provide curative effects and is frequently hampered by recurrence. This suggests the presence of a reservoir for MAC in the environment surrounding patients. We previously reported the recovery of MAC isolates from the residential bathrooms of outpatients. In the present study, to ascertain the colonizing sites and the possibility of an MAC reservoir in the bathrooms of patients, we tested the recovery and the genetic diversity of MAC isolates from 6 sites of specimens, including 2 additional sampling sites, inside the showerhead and the bathtub inlet, in the residential bathrooms of patients with pulmonary MAC disease. MAC isolates were recovered from 15 out of the 29 bathrooms (52%), including specimens from 14 bathtub inlets and 3 showerheads. Nearly half of these bathrooms (7/15) contained MAC strains that were identical or similar to their respective clinical isolates Additionally, in 5 out of 15 bathrooms, polyclonal colonization was revealed by pulsed-field gel electrophoresis. The results imply that colonization of MAC organisms in the bathrooms of MAC patients occurs predominantly in the bathtub inlets, and there is thus a risk of infection and/or reinfection for patients via use of the bathtub and other sites in the bathroom.
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Banhos , Contaminação de Equipamentos , Hospitais , Complexo Mycobacterium avium/isolamento & purificação , Quartos de Pacientes , Biofilmes , Distribuição de Qui-Quadrado , Eletroforese em Gel de Campo Pulsado , Zeladoria Hospitalar , Humanos , Japão , Complexo Mycobacterium avium/genética , Complexo Mycobacterium avium/crescimento & desenvolvimento , Infecção por Mycobacterium avium-intracellulare/microbiologia , Engenharia Sanitária , Estatísticas não Paramétricas , Microbiologia da ÁguaRESUMO
Japan reportedly has high incidence rate of nontuberculous mycobacterial lung disease (14.7 cases per 100,000 person in 2014). In Japan, the most common etiology is Mycobacterium avium subsp. hominissuis (MAH). MAH is a typical inhabitant of the environment, especially bathrooms, which are considered as a potential source of infection. To corroborate this hypothesis, we determined the detection rate of MAH in bathrooms of healthy volunteers by an ordinary culture method and we analyzed the genetic relatedness of these isolates with those from patients and other sources. We collected swabs of bathtub inlets, showerheads, bathroom drains, and shower water from 180 residences throughout Japan. The overall MAH detection rate was 16.1%, but the rate varied among regions: it was high in Kanto (9/34, 26.5%) and Kinki (9/33, 27.3%), but low in Kyushu (0/11, 0%), Tohoku (1/23, 4.3%), and Hokkaido (2/23, 8.7%). MAH was detected primarily in bathtub inlet samples (25 out of 170 residences). Variable numbers of tandem repeats (VNTR) analysis was used to examine the genetic relatedness of 57 MAH isolates from bathrooms of the healthy volunteers with human clinical isolates. A minimum spanning tree generated on the basis of the VNTR data indicated that isolates from the bathrooms of the healthy volunteers had a high degree of genetic relatedness with those from Japanese patients, bathrooms of patients, and river water, but not with those from Russian patients and Japanese pigs. These results showed that bathtub inlets in Japan provide an environmental niche for MAH and suggest that bathrooms are one of the important infection sources of MAH in Japan. Understanding country-specific lifestyle habits, such as bathing in Japan, as well as the genetic diversity of MAH, will help in elucidating the sources of this pathogen.
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Pneumopatias/microbiologia , Repetições Minissatélites , Mycobacterium avium/classificação , Rios/microbiologia , DNA Bacteriano/genética , Voluntários Saudáveis , Humanos , Japão , Mycobacterium avium/genética , Mycobacterium avium/isolamento & purificação , Filogeografia , Federação Russa , Microbiologia do Solo , Banheiros , Microbiologia da ÁguaRESUMO
Bacteria coordinate assembly of the cell wall as well as synthesis of cellular components depending on the growth state. The mycobacterial cell wall is dominated by mycolic acids covalently linked to sugars, such as trehalose and arabinose, and is critical for pathogenesis of mycobacteria. Transfer of mycolic acids to sugars is necessary for cell wall biogenesis and is mediated by mycolyltransferases, which have been previously identified as three antigen 85 (Ag85) complex proteins. However, the regulation mechanism which links cell wall biogenesis and the growth state has not been elucidated. Here we found that a histone-like protein has a dual concentration-dependent regulatory effect on mycolyltransferase functions of the Ag85 complex through direct binding to both the Ag85 complex and the substrate, trehalose-6-monomycolate, in the cell wall. A histone-like protein-deficient Mycobacterium smegmatis strain has an unusual crenellated cell wall structure and exhibits impaired cessation of glycolipid biosynthesis in the growth-retarded phase. Furthermore, we found that artificial alteration of the amount of the extracellular histone-like protein and the Ag85 complex changes the growth rate of mycobacteria, perhaps due to impaired down-regulation of glycolipid biosynthesis. Our results demonstrate novel regulation of cell wall assembly which has an impact on bacterial growth.
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Proteínas de Bactérias/metabolismo , Parede Celular/metabolismo , Proteínas de Ligação a DNA/metabolismo , Histonas/metabolismo , Mycobacterium smegmatis/citologia , Mycobacterium smegmatis/metabolismo , Aciltransferases/metabolismo , Adesinas Bacterianas/metabolismo , Antígenos de Bactérias/metabolismo , Proteínas de Bactérias/genética , Fatores Corda , Proteínas de Ligação a DNA/genética , Regulação Bacteriana da Expressão Gênica , Glicolipídeos , Histonas/química , Histonas/genética , Mycobacterium bovis , Mycobacterium smegmatis/genética , Ligação ProteicaRESUMO
The distribution of Mycobacterium avium-intracellulare complex (MAC) in residences was examined. MAC was only recovered from bathrooms but not from other sites of residences. The appearance ratio in the bathrooms of patients with pulmonary MAC was significantly higher than that in healthy volunteers' bathrooms (P=.01). For 2 patients, the genotypes of environmental isolates were identical to their respective clinical isolates.
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Complexo Mycobacterium avium/isolamento & purificação , Infecção por Mycobacterium avium-intracellulare/microbiologia , Mycobacterium avium/isolamento & purificação , Características de Residência , Infecções Respiratórias/microbiologia , Humanos , Higiene , Japão , Mycobacterium avium/classificação , Complexo Mycobacterium avium/classificação , Infecções Oportunistas/diagnóstico , Infecções Oportunistas/microbiologia , Valores de Referência , Microbiologia da ÁguaRESUMO
Numerous studies have revealed a continuous increase in the worldwide incidence and prevalence of non-tuberculous mycobacteria (NTM) diseases, especially pulmonary Mycobacterium avium complex (MAC) diseases. Although it is not clear why NTM diseases have been increasing, one possibility is an increase of mycobacterial infection sources in the environment. Thus, in this review, we focused on the infection sources of pathogenic NTM, especially MAC. The environmental niches for MAC include water, soil, and dust. The formation of aerosols containing NTM arising from shower water, soil, and pool water implies that these niches can be infection sources. Furthermore, genotyping has shown that clinical isolates are identical to environmental ones from household tap water, bathrooms, potting soil, and garden soil. Therefore, to prevent and treat MAC diseases, it is essential to identify the infection sources for these organisms, because patients with these diseases often suffer from reinfections and recurrent infections with them. In the environmental sources, MAC and other NTM organisms can form biofilms, survive within amoebae, and exist in a free-living state. Mycobacterial communities are also likely to occur in these infection sources in households. Water distribution systems are a transmission route from natural water reservoirs to household tap water. Other infection sources include areas with frequent human contact, such as soil and bathrooms, indicating that individuals may carry NTM organisms that concomitantly attach to their household belongings. To explore the mechanisms associated with the global spread of infection and MAC transmission routes, an epidemiological population-wide genotyping survey would be very useful. A good example of the power of genotyping comes from M. avium subsp. hominissuis, where close genetic relatedness was found between isolates of it from European patients and pigs in Japan and Europe, implying global transmission of this bacterium. It is anticipated that whole genome sequencing technologies will improve NTM surveys so that the mechanisms for the global spread of MAC disease will become clearer in the near future. Better understanding of the niches exploited by MAC and its ecology is essential for preventing MAC infections and developing new methods for its effective treatment and elimination.
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Mycobacterium avium subsp. hominissuis (MAH) is the major causative agent of nontuberculous mycobacteriosis, the representative case of environment-related infectious diseases the incidence of which is increasing in industrialized countries. MAH is found in biofilm in drinking water distribution system and residential environments. We investigated the effect of gaseous and nutritional conditions, and the role of glycopeptidolipids (GPLs) on biofilm-like pellicle formation in MAH. Pellicle formation was observed under 5% oxygen in Middlebrook 7H9 broth containing 0.2% glycerol and 10% albumin-dextrose-catalase enrichment but not under normoxia or in nutrient-poor media. An analysis of 17 environmental isolates revealed that hypoxia (5% oxygen) preferentially enhanced pellicle formation both in plastic plates and in glass tubes, compared with hypercapnia (5% carbon dioxide). Wild-type strains (WT) developed much thicker pellicles than GPL-deficient rough mutants (RM). WT bacterial cells distributed randomly and individually in contrast to that RM cells positioned linearly in a definite order. Exogenous supplementation of GPLs thickened the pellicles of RM, resulting in a similar morphological pattern to WT. These data suggest a significant implication of eutrophication and hypoxia in biofilm-like pellicle formation, and a functional role of GPLs on development of pellicles in MAH.
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Biofilmes/crescimento & desenvolvimento , Microbiologia Ambiental , Glicolipídeos/metabolismo , Infecções por Mycobacterium não Tuberculosas/microbiologia , Mycobacterium avium/fisiologia , Fenômenos Fisiológicos da Nutrição , Consumo de Oxigênio , Biofilmes/efeitos dos fármacos , Desinfetantes/farmacologia , Meio Ambiente , Humanos , Hipóxia , Mutação , Mycobacterium avium/efeitos dos fármacos , Mycobacterium avium/ultraestrutura , FenótipoRESUMO
Mycobacterium avium subsp. hominissuis (MAH) is one of the most common nontuberculous mycobacterial species responsible for chronic lung disease in humans. Despite increasing worldwide incidence, little is known about the genetic mechanisms behind the population evolution of MAH. To elucidate the local adaptation mechanisms of MAH, we assessed genetic population structure, the mutual homologous recombination, and gene content for 36 global MAH isolates, including 12 Japanese isolates sequenced in the present study. We identified five major MAH lineages and found that extensive mutual homologous recombination occurs among them. Two lineages (MahEastAsia1 and MahEastAsia2) were predominant in the Japanese isolates. We identified alleles unique to these two East Asian lineages in the loci responsible for trehalose biosynthesis (treS and mak) and in one mammalian cell entry operon, which presumably originated from as yet undiscovered mycobacterial lineages. Several genes and alleles unique to East Asian strains were located in the fragments introduced via recombination between East Asian lineages, suggesting implication of recombination in local adaptation. These patterns of MAH genomes are consistent with the signature of distribution conjugative transfer, a mode of sexual reproduction reported for other mycobacterial species.