MYCOBACTERIA Flashcards
i. Mycobacterium tuberculosis
ii. Mycobacterium bovis
iii. Mycobacterium africanum
iv. Mycobacterium canetti
v. Mycobacterium microti
. Mycobacterium tuberculosis complex
Non-tuberculous mycobacteria
Group I – photochromogens, produces
pigment when there is light, no light = no
pigment (photo – light, chromo –
pigment)
ii. Group II – scotochromogens, produces
pigment with and without the presence
of light.
iii. Group III – non-photochromogens, does
not produce any kind of pigment.
➢ Group I, II, III are slow
growers.
iv. Group IV – rapid growers
- Slender, slightly curved or straight, rod-shaped organisms
MYCOBACTERIA
- Non-motile and do not form spores
MYCOBACTERIA
- The cell wall has extremely high lipid content; thus, mycobacterial cells
MYCOBACTERIA
- Resist staining with commonly used basic aniline dyes, such as those used in the Gram stain, at room temperature.
MYCOBACTERIA
- Take up dye with increased staining time or application of heat but resist decolorization with acid-ethanol
MYCOBACTERIA
- This characteristic is referred to as acid fastness—hence, the term AFB—and
MYCOBACTERIA
strictly aerobic, but increased carbon dioxide (CO2) will enhance the growth of some species.
MYCOBACTERIA
- Cause pulmonary tuberculosis
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- Studied using AFS (Acid Fast Staining)
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- Important component is the Mycolic acid (targeted by the antibiotics that are used
MYCOBACTERIA
- Antibiotics of Mycobacteria
Isoniazid, Rifampin
- Consists of M. tuberculosis, M. bovis
MYCOBACTERIUM TUBERCULOSIS COMPLEX
- (including the vaccination strain bacillus Calmette-Guérin), M. africanum, M. canettii, and
M. microti. M. africanum
MYCOBACTERIUM TUBERCULOSIS COMPLEX
usually a disease of the respiratory tract.
- TB
are acquired from persons with active disease who are excreting viable bacilli by sneezing or talking.
- Tubercle bacilli
an organization of lymphocytes, macrophages, fibroblasts, and
* capillaries.
granuloma
or granuloma may be formed
- Hard tubercle
o Granuloma treatment is from
9-12 months
screening test or the positive PPD (purified protein derivatives) skin test also known as Mantoux skin test.
- Clinical diagnosis of primary TB
ositive PPD (purified protein derivatives) skin test also known as
Mantoux skin test.
- Other tests for pulmonary tuberculosis
X-ray, culture of the sputum, AFS using the sputum
Diagnosis is confirmed by
y stained smear and culture of sputum, gastric aspirates, or bronchoscopy specimens
o Aside from your lungs, it can also infect other organs through hematogenous spread (spread through blood circulation)
- Extrapulmonary Tuberculosis
refers to the seeding of many organs outside the pulmonary tree with AFB through hematogenous spread. (sesame seeds)
- Miliary TB
unexplained pleural effusion with mononuclear pleurocytosis, manifests as cough, fever, and chest pain, resembling the presentation of bacterial pneumonia.
- Pleurisy
– inflammation of the lymph nodes
- Lymphadenitis
of the spine is referred to as Pott disease.
- Skeletal TB
, skinny, and not able to stand up
o Positive in TB
examination usually reveals an elevated protein level, decreased glucose level, and a predominance of lymphocytes.
- Cerebrospinal fluid (CSF)
malachite green, egg white)
LJ medium
characterized as cauliflower appearance.
- Mycobacterium tuberculosis
colonies typically raised, with a dry, rough appearance
- Mycobacterium tuberculosis
nonpigmented and classically described as being buff-colored
- Mycobacterium tuberculosis
- Optimal growth occurs at
35° C to 37° C.
- For pulmonary TB, treatment typically involves
9-month course of therapy with isoniazid and rifampin, usually once per day the first month and twice a week thereafte
o for severe/chronic TB, therap
12 months
first life of drugs for Pulmonary Tuberculosis.
o isoniazid and rifampin
inhibits mycolic acid
o Isoniazid
inhibits RNA polymerase
Rifampin
- Regimens also include a 2- to 8-week initial course of
streptomycin or ethambutol
may be added to the regimen if there is a suspicion of lowered cellular immunity and a need to obtain bactericidal levels of antimycobacterial activity intracellularly in macrophages.
- Pyrazinamide (PZA)
defined as resistance to at least isoniazid and rifampin
- MDR-TB (multi drug resistant TB)
is defined as resistance to isoniazid and rifampin plus resistance to any fluoroquinolone and at least one of three injectable second-line anti-TB drugs—the aminoglycosides amikacin, kanamycin, or capreomycin.
- Extensively drug-resistant TB (XDR-TB)
RIPES (Rifampin, Isoniazid, Pyrazinamide, Ethambutol, Streptomycin)
o Primary drugs
Aminoglycosides Amikacin, Kanamycin, or Capreomycin.
o Secondary drugs
- TB primarily in cattle but also in other ruminants, as well as in dogs, cats, swine, parrots, and humans. (domestic animals)
MYCOBACTERIUM BOVIS
- The disease in humans closely resembles that caused by M. tuberculosis and is treated similarly.
MYCOBACTERIUM BOVIS
- days of incubation at C.
21 , 37°C
o niacin-negative
o do not reduce nitrate
o do not grow in the presence of (T2H) thiophene-2-carboxylic acid hydrazide
- Test results of M. bovis
- Causes TB in Tropical Africa
MYCOBACTERIUM AFRICANUM
- Associated with AIDS patients
MYCOBACTERIUM CANETTI
- Causes TB for both immunocompromised and competent
MYCOBACTERIUM MICROTI
