Mycobacteria Flashcards
Genus mycobacterium morphology
Rod-shaped aerobic non motile do not have a cap show me the strictly gram-positive or gram-negative are usually considered gram positive because they lack outer cell membrane typical acid-fast bacteria when grown in liquid they form mould like pellicles
Mycobacterium species can be identified by looking at
Growth rate Colony morphology pigmentation biochemical profiles molecular methods
M tuberculosis
Non motile Aerobic No capsule No spores Gram + Acid fast Rod shaped
Pathogenesis and pathology of M tuberculosis
Infection is by inhalation
Which results in pulmonary tuberculosis
Primary infection usually occurs when there when these infections droplet nuclei are inhaled and lodge in lung alveoli in the lungs the bustling engulfed by the alveolar macrophages but the macrophages are in capable of digesting the bacterium is that the best ally multipliers at the macrophages and form lesions
Lesions classified as either
Oxidative lesions that occur as a result of acute inflammatory reaction the exudate secreted new includes polymorphonuclear leukocytes and monocytes these lesions are common in lung tissue and cause symptoms similar to pneumonia they may heal with the development of necrotic tissue or the lesions may develop into the second form the reproductive lesion in productive relations there is no accident instead macrophages surround the foci of infection and form granulomas which consist of several
Granulomas zones
Central zone area contains multinucleated giant bacilli
mid zone contains epithelioid cells
outer zone consist of fibroblasts lymphocytes and monocytes
Inside granulomas most bacilli die from acidosis and anoxia
Military distribution bacilli enter bloodstream and can be distributed to all organs
Primary and secondary infection
Bacilli become dormant and can later be reactivated causing post primary infection- primary
Bacilli may be swallowed and enter the stomach and intestines- secondary
Diagnosis of tuberculosis
Tuberculin test to assess people for latent TB infection a purified protein derivative is injected just under the skin if they injected individual has never been in contact with mycobacteria there will be no reaction at the site of the injection if the individual has had a primary TB infection and induration (hardening) edema( swelling) and erythema (redness) will develop within 24 to 48 hours a positive reaction does not mean that the individual has an active TB infection but as they may have cleared the primary infection but will be at risk of reactivation of the primary infection
Treatment of tuberculosis
Treatment using drugs that women first-line drugs used against tuberculosis are isoniazid and and rifampin pyrazinamide ethambutol streptomycin
second-line drugs are either more toxic for the patient or less effective against the bacteria and I used only treatment with the first-line drug is failing with the bacteria are known to be drug-resistant.
Mycobacterium leprae
Causes leprosy addis figuring disease that king without in permanent injury to the skin muslims and i transmitted from human to human probably fire nasal secretion and shed skin not very contagious incubation slow and a may be not symptoms for between 2 to 40 years lesions tend to form on colet tissues such a skin nose superficial nerves ears eyes larynx pharynx testicles
Two major types of leprae
Lepromatous malignant Tuberculoid benign Diagnosis by scraping skin and nasal mucosa skin biopsies PCR Acid fast staining Microscopy
Treatment of leprae
Involves on or more drugs with sulfones being first line drugs for both forms
Over a number of months but may also be over years to clear infection completey
Diagnosis and treatment
Non tubercular mycobacteria
Culture conducted at a range of temperatures using diverse media or additives growth rate colony morphology and the presence of pigmentation can help to identify the species microscopy acid-fast staining to ascertain whether it is a mycobacterium does not differentiate species biochemical testing molecular methods including molecular probes HPLC and pcr-based techniques
