Mycobacterium tuberculosis in the context of "Lung cavity"

Tuberculosis (TB) (RP:/tjuːˈbɜːrkjuːˌloʊsɪs/ tew-BER-kew-loh-sis, also /ˌtjuːbərkjuːˈloʊsɪs/ tew-bər-kew-LOH-sis), also known colloquially as the "white death", or historically as consumption, is a contagious disease usually caused by Mycobacterium tuberculosis (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, in which case it is known as inactive or latent tuberculosis. A small proportion of latent infections progress to active disease that, if left untreated, can be fatal. Typical symptoms of active TB are chronic cough with blood-containing mucus, fever, night sweats, and weight loss. Infection of other organs can cause a wide range of symptoms.

Tuberculosis is spread from one person to the next through the air when people who have active TB in their lungs cough, spit, speak, or sneeze. People with latent TB do not spread the disease. A latent infection is more likely to become active in those with weakened immune systems. There are two principal tests for TB: interferon-gamma release assay (IGRA) of a blood sample, and the tuberculin skin test.

Latent tuberculosis (LTB), also called latent tuberculosis infection (LTBI), is when a person is infected with Mycobacterium tuberculosis, but does not have active tuberculosis (TB). Active tuberculosis can be contagious while latent tuberculosis is not, and therefore it is not possible to get TB from someone with latent tuberculosis. Various treatment regimens are in use for latent tuberculosis. They generally need to be taken for several months.

Tuberculosis is diagnosed by finding Mycobacterium tuberculosis bacteria in a clinical specimen taken from the patient. While other investigations may strongly suggest tuberculosis as the diagnosis, they cannot confirm it.

A complete medical evaluation for tuberculosis (TB) must include a medical history, a physical examination, a chest X-ray and microbiological examination (of sputum or some other appropriate sample). It may also include a tuberculin skin test, other scans and X-rays, surgical biopsy.

Acute septic arthritis, infectious arthritis, suppurative arthritis, pyogenic arthritis, osteomyelitis, or joint infection is the invasion of a joint by an infectious agent resulting in joint inflammation. Generally speaking, symptoms typically include redness, heat and pain in a single joint associated with a decreased ability to move the joint. Onset is usually rapid. Other symptoms may include fever, weakness and headache. Occasionally, more than one joint may be involved, especially in neonates, younger children and immunocompromised individuals. In neonates, infants during the first year of life, and toddlers, the signs and symptoms of septic arthritis can be deceptive and mimic other infectious and non-infectious disorders.

In children, septic arthritis is usually caused by non-specific bacterial infection and commonly hematogenous, i.e., spread through the bloodstream. Septic arthritis and/or acute hematogenous osteomyelitis usually occurs in children with no co-occurring health problems. Other routes of infection include direct trauma and spread from a nearby abscess. Other less common cause include specific bacteria as mycobacterium tuberculosis, viruses, fungi and parasites. In children, however, there are certain groups that are specifically vulnerable to such infections, namely preterm infants, neonates in general, children and adolescents with hematologic disorders, renal osteodystrophy, and immune-compromised status. In adults, vulnerable groups include those with an artificial joint, prior arthritis, diabetes and poor immune function. Diagnosis is generally based on accurate correlation between history-taking and clinical examination findings, and basic laboratory and imaging findings like joint ultrasound.

Mycobacterium leprae (also known as the leprosy bacillus or Hansen's bacillus) is oneof the two species of bacteria that cause Hansen's disease (leprosy), a chronic but curable infectious disease that damages the peripheral nerves and targets the skin, eyes, nose, and muscles.

It is an acid-fast, Gram-positive, rod shaped bacterium and an obligate intracellular parasite, which means, unlike its relative Mycobacterium tuberculosis, it cannot be grown in cell-free laboratory media. This is likely due to gene deletion and decay that the genome of the species has experienced via reductive evolution, which has caused the bacterium to depend heavily on its host for nutrients and metabolic intermediates. It has a narrow host range and apart from humans, the only other natural hosts are nine-banded armadillo and red squirrels. The bacteria infect mainly macrophages and Schwann cells, and are typically found congregated as a palisade.

Acid-fastness is a physical property of certain bacteria, protozoa, and eukaryotic cells, as well as some subcellular structures, referring to their resistance to decolorization by acids during laboratory staining procedures. Once stained as part of a sample, these organisms can resist the acid and/or ethanol-based decolorization procedures common in many staining protocols, hence the name acid-fast.

Historically, acid-fast stains were thought to stain lipids of the cells based on the observed charectistics of cell staining under a wide range of conditions, although the results were limited by the tools available, however as early as 1959 there were observations of how nucleic acids were acid fast. Dyes such as carbol fuchsin and auramine O penetrate the cell and bind to DNA and RNA, producing characteristic red or yellow-green fluorescence, respectively. The property of “acid-fastness” therefore reflects the organism’s ability to retain these dyes after acid–alcohol decolorization, a feature determined mainly by the integrity and composition of the outer cell wall rather than by any specific lipid chemistry.

Mycobacteriaceae is a family of bacteria in the phylum Actinomycetota. Its name is derived from the Mycobacterium genus, which includes pathogens known to cause serious diseases in mammals, including tuberculosis (M. tuberculosis) and leprosy (M. leprae) in humans. The Greek prefix myco- means 'fungus', alluding to the mold-like appearance of these organisms on agar plates.

Mycolic acids are long fatty acids found in the cell walls of Mycobacteriales taxon, a group of bacteria that includes Mycobacterium tuberculosis, the causative agent of the disease tuberculosis. They form the major component of the cell wall of many Mycobacteriales species. Despite their name, mycolic acids have no biological link to fungi; the name arises from the filamentous appearance their presence gives Mycobacteriales under high magnification. The presence of mycolic acids in the cell wall also gives Mycobacteriales a distinct gross morphological trait known as "cording". Mycolic acids were first isolated by Stodola et al. in 1938 from an extract of M. tuberculosis.

Mycolic acids are composed of a longer beta-hydroxy chain with a shorter alpha-alkyl side chain. Each molecule contains between 60 and 90 carbon atoms. The exact number of carbons varies by species and can be used as an identification aid. Most mycolic acids also contain various functional groups.

The Ziehl–Neelsen stain, also known as the acid-fast stain, is a bacteriological staining technique used in cytopathology and microbiology to identify acid-fast bacteria under microscopy, particularly members of the Mycobacterium genus. This staining method was initially introduced by Paul Ehrlich (1854–1915) and subsequently modified by the German bacteriologists Franz Ziehl (1859–1926) and Friedrich Neelsen (1854–1898) during the late 19th century.

The acid-fast staining method, in conjunction with auramine phenol staining, serves as the standard diagnostic tool and is widely accessible for rapidly diagnosing tuberculosis (caused by Mycobacterium tuberculosis) and other diseases caused by atypical mycobacteria, such as leprosy (caused by Mycobacterium leprae) and Mycobacterium avium-intracellulare infection (caused by Mycobacterium avium complex) in samples like sputum, gastric washing fluid, and bronchoalveolar lavage fluid. These acid-fast bacteria possess a waxy lipid-rich outer layer that contains high concentrations of mycolic acid, rendering them resistant to conventional staining techniques like the Gram stain.