-
Cellular Microbiology Jun 2012The species Mycobacterium avium includes several subspecies representing highly specialized avian and mammalian pathogens, non-obligatory pathogens of immune compromised... (Review)
Review
The species Mycobacterium avium includes several subspecies representing highly specialized avian and mammalian pathogens, non-obligatory pathogens of immune compromised humans and saprophitic organisms. Recently obtained information concerning the diversity of M. avium genomic structures not only clarified phylogenic relationships within this species, but began to shed light on the question of how such closely related microorganisms adapt to the occupation of distinct ecological niches. In this review we discuss specific features of M. avium genetic composition, as well as genetic and molecular aspects of M. avium hominissuis (MAH)-triggered disease pathogenesis, including virulence, penetration, immune response manipulation and host genetic control.
Topics: Animals; Bacterial Proteins; Cell Wall; Gene Expression; Gene Expression Regulation, Bacterial; Genome, Bacterial; Host-Pathogen Interactions; Humans; Microbial Viability; Mycobacterium avium; Tuberculosis, Pulmonary
PubMed: 22348543
DOI: 10.1111/j.1462-5822.2012.01776.x -
Future Microbiology Jul 2021is an emerging opportunistic pathogen, globally. Infections caused by are laborious to treat and could result in drug resistance. This review discusses the importance... (Review)
Review
is an emerging opportunistic pathogen, globally. Infections caused by are laborious to treat and could result in drug resistance. This review discusses the importance of many factors including the cell wall in pathogenesis, since this unique structure modulates the pathogen's ability to thrive in various hosts and environmental niches including conferring resistance to killing by antimicrobials. More research efforts in future are solicited to develop novel therapeutics targeting . The complete eradication of infection in immunocompromised individuals would need a deeper understanding of the source of infection, unique underlying mechanisms and its uncharacterized pathways. This could, perhaps in future, hold the key to target and treat more effectively.
Topics: Anti-Infective Agents; Cell Wall; Humans; Mycobacterium avium; Mycobacterium avium-intracellulare Infection
PubMed: 34227394
DOI: 10.2217/fmb-2021-0016 -
Clinical Microbiology Reviews Apr 2007The past several years have witnessed an upsurge of genomic data pertaining to the Mycobacterium avium complex (MAC). Despite clear advances, problems with the detection... (Review)
Review
The past several years have witnessed an upsurge of genomic data pertaining to the Mycobacterium avium complex (MAC). Despite clear advances, problems with the detection of MAC persist, spanning the tests that can be used, samples required for their validation, and the use of appropriate nomenclature. Additionally, the amount of genomic variability documented to date greatly outstrips the functional understanding of epidemiologically different subsets of the organism. In this review, we discuss how postgenomic insights into the MAC have helped to clarify the relationships between MAC organisms, highlighting the distinction between environmental and pathogenic subsets of M. avium. We discuss the availability of various genetic targets for accurate classification of organisms and how these results provide a framework for future studies of MAC variability. The results of postgenomic M. avium study provide optimism that a functional understanding of these organisms will soon emerge, with genomically defined subsets that are epidemiologically distinct and possess different survival mechanisms for their various niches. Although the status quo has largely been to study different M. avium subsets in isolation, it is expected that attention to the similarities and differences between M. avium organisms will provide greater insight into their fundamental differences, including their propensity to cause disease.
Topics: Bacterial Proteins; Chaperonin 60; Chaperonins; DNA Transposable Elements; Genetic Variation; Genome, Bacterial; Genomics; Humans; Mycobacterium avium; Mycobacterium avium Complex; Mycobacterium avium-intracellulare Infection; Phylogeny; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Serotyping
PubMed: 17428883
DOI: 10.1128/CMR.00036-06 -
Infection, Genetics and Evolution :... Jan 2014Mycobacterium avium, one of the species of the M. avium complex (MAC), includes 4 subspecies, i.e., M. avium subsp. hominissuis (MAH), M. avium subsp. avium (MAA), M.... (Review)
Review
Mycobacterium avium, one of the species of the M. avium complex (MAC), includes 4 subspecies, i.e., M. avium subsp. hominissuis (MAH), M. avium subsp. avium (MAA), M. avium subsp. silvaticum (MAS) and M. avium subsp. paratuberculosis (MAP), in turn classified into the S (sheep) and C (cattle) types. These subspecies, although closely related, represent distinct organisms, each endowed with specific pathogenetic and host range characteristics, ranging from environmental opportunistic bacteria that cause infections in swine and immunocompromised patients to pathogens of birds and ruminants. The present review summarizes the basic epidemiological and pathological features of the M. avium subspecies, describes the major genomic events responsible of M. avium subspecies diversity (insertion sequences, sequence variations in specific chromosome loci or genes, deletions, duplications and insertions of large genomic regions) and then reconstructs the phylogenetic relationships among the M. avium subspecies.
Topics: Animals; Genetic Variation; Genome, Bacterial; Humans; Mycobacterium avium; Phylogeny; Species Specificity; Tuberculosis
PubMed: 24345519
DOI: 10.1016/j.meegid.2013.12.007 -
Frontiers in Bioscience : a Journal and... Jul 1999Mycobacterium avium is an environmental microorganism that is adapted to live both in the environment (mainly in water and soil) and in bird, fish and mammal hosts. In... (Review)
Review
Mycobacterium avium is an environmental microorganism that is adapted to live both in the environment (mainly in water and soil) and in bird, fish and mammal hosts. In humans, M. avium infection is seen in patients with some sort of immunosuppression, such as patients with chronic lung disease, and Acquired Immunodeficiency Syndrome. More recently, other populations were shown to be at risk to develop M. avium disease. For the majority of time, humans acquire M. avium through the intestinal tract where the bacterium comes in contact with and translocates the intestinal mucosa. M. avium possesses a unique manner to interact with the intestinal mucosa, and, following invasion, can enter and survive within macrophages and monocytes. Although in vitro entry seems to be dependent on binding to the complement receptor, this finding has not been observed in vivo where the bacterium appears to enter macrophages by alternative mechanisms. The bacterium appears to trigger little inflammatory response, and is able to adapt itself to different environments in the host.
Topics: Bacterial Translocation; HIV-1; Humans; Intestinal Mucosa; Macrophages; Mycobacterium avium; Phagocytes
PubMed: 10417376
DOI: 10.2741/sangari -
Emerging Infectious Diseases Mar 2019Attention to environmental sources of Mycobacterium avium complex (MAC) infection is a vital component of disease prevention and control. We investigated MAC...
Attention to environmental sources of Mycobacterium avium complex (MAC) infection is a vital component of disease prevention and control. We investigated MAC colonization of household plumbing in suburban Philadelphia, Pennsylvania, USA. We used variable-number tandem-repeat genotyping and whole-genome sequencing with core genome single-nucleotide variant analysis to compare M. avium from household plumbing biofilms with M. avium isolates from patient respiratory specimens. M. avium was recovered from 30 (81.1%) of 37 households, including 19 (90.5%) of 21 M. avium patient households. For 11 (52.4%) of 21 patients with M. avium disease, isolates recovered from their respiratory and household samples were of the same genotype. Within the same community, 18 (85.7%) of 21 M. avium respiratory isolates genotypically matched household plumbing isolates. Six predominant genotypes were recovered across multiple households and respiratory specimens. M. avium colonizing municipal water and household plumbing may be a substantial source of MAC pulmonary infection.
Topics: Adult; Aged; Aged, 80 and over; Environmental Microbiology; Female; Genotype; History, 21st Century; Humans; Male; Middle Aged; Minisatellite Repeats; Multilocus Sequence Typing; Mycobacterium avium; Mycobacterium avium Complex; Mycobacterium avium-intracellulare Infection; Philadelphia; Phylogeny; Public Health Surveillance; Water Microbiology; Whole Genome Sequencing
PubMed: 30789130
DOI: 10.3201/eid2503.180336 -
Future Microbiology 2014
Topics: Anti-Bacterial Agents; Crohn Disease; Global Health; Humans; Macrophages; Mycobacterium avium subsp. paratuberculosis; Phagocytosis
PubMed: 25156371
DOI: 10.2217/fmb.14.52 -
Virulence 2015Mycobacterium avium subspecies hominissuis (MAH) is an opportunistic pathogen and causes nontuberculous infections in immune compromised individuals, an emerging problem...
Mycobacterium avium subspecies hominissuis (MAH) is an opportunistic pathogen and causes nontuberculous infections in immune compromised individuals, an emerging problem that has been recognized worldwide. Understanding the pathogenesis of this organism is important as better treatment and prevention options are needed. Microaggregates form when two or more bacterial cells join at a surface. MAH forms micgroaggregates to promote its entry in to epithelial cells and cause infection. The mechanisms involved in the interaction between the microaggregate and the host are becoming clearer as the molecules involved in this process are being uncovered. Microaggregate Invasion Protein-1 (MIP-1) is now described as having a major role in the invasion of epithelial cells by MAH.
Topics: Animals; Epithelial Cells; Female; Humans; Mycobacterium avium
PubMed: 26364883
DOI: 10.1080/21505594.2015.1088633 -
Journal of Medical Microbiology Oct 2018To measure the aerosolization of Mycobacterium avium subspecies hominissuis and Mycobacterium abscessus subspecies abscessus from ultrasonic humidifiers.
PURPOSE
To measure the aerosolization of Mycobacterium avium subspecies hominissuis and Mycobacterium abscessus subspecies abscessus from ultrasonic humidifiers.
METHODOLOGY
An ultrasonic humidifier was filled with sterile tap water and inoculated with water-acclimated cells of either the M. avium or M. abscessus strains to achieve a range of densities similar to those of mycobacteria found in drinking waters. During operation of the humidifier, aerosols were collected using an Andersen 6-Stage Cascade Sampler.
RESULTS
Cells of the M. avium and M. abscessus strains were readily aerosolized and recovered in particles (1-5 µm diameter); small enough to enter the furthest reaches of the human lung. Aerosolization of M. abscessus was significantly reduced in the presence of a normal drinking water bacterial flora. Significantly greater numbers of M. avium cells were aerosolized from high-density suspensions (1200 c.f.u. ml), than from low-density (120 c.f.u. ml) and very low-density (12 c.f.u. ml) suspensions.
CONCLUSIONS
This report documents the potential for M. avium subspecies hominissuis and M. abscessus subspecies abscessus cells in drinking water to be aerosolized from one type of portable humidifier; an ultrasonic humidifier. Care should be taken in using an ultrasonic humidifier where an individual at risk for mycobacterial pulmonary disease could be exposed.
Topics: Aerosols; Air Pollution, Indoor; Equipment Contamination; Fresh Water; Humidifiers; Mycobacterium abscessus; Mycobacterium avium
PubMed: 30113303
DOI: 10.1099/jmm.0.000822 -
Veterinary Research Jun 2015Mycobacterium avium subspecies paratuberculosis (Map) is an important pathogen that causes a chronic, progressive granulomatous enteritis known as Johne's disease or... (Review)
Review
Mycobacterium avium subspecies paratuberculosis (Map) is an important pathogen that causes a chronic, progressive granulomatous enteritis known as Johne's disease or paratuberculosis. The disease is endemic in many parts of the world and responsible for considerable losses to the livestock and associated industries. Diagnosis and control are problematic, due mostly to the long incubation period of the disease when infected animals show no clinical signs and are difficult to detect, and the ability of the organism to survive and persist in the environment. The existence of phenotypically distinct strains of Map has been known since the 1930s but the genetic differentiation of Map strain types has been challenging and only recent technologies have proven sufficiently discriminative for strain comparisons, tracing the sources of infection and epidemiological studies. It is important to understand the differences that exist between Map strains and how they influence both development and transmission of disease. This information is required to develop improved diagnostics and effective vaccines for controlling Johne's disease. Here I review the current classification of Map strain types, the sources of the genetic variability within strains, growth characteristics and epidemiological traits associated with strain type and the influence of strain type on infection and pathogenicity.
Topics: Genetic Variation; Mycobacterium avium subsp. paratuberculosis; Paratuberculosis; Virulence
PubMed: 26092160
DOI: 10.1186/s13567-015-0203-2