Acid Fast Bacteria Part 2 Flashcards
Often called the MAC or MAI (M avium intracellulare) complex.
Grow optimally at 41°C and produce smooth, soft , nonpigmented colonies.
M avium complex
Patients at risk include those with .
cystic fibrosis and pulmonary alveolar proteinosis
Pulmonary MAC disease has also been described in middle-aged to elderly women in the absence of chronic lung disease and has been referred to as which this form of the disease is indolent and over time is characterized by nodules in the middle lobes and lingula that progress to cavitation.
Lady Windermere syndrome.
Is the most common presentation in young children (< 5 years of age).
Cervical lymphadenitis
The major manifestation of M avium complex
unilateral, firm adenopathy; fever is generally absent.
MAC organisms routinely are resistant to
first-line anti-tuberculosis drugs
Treatment for M avium complex
- With either clarithromycin or azithromycin plus EMB is a preferred initial therapy
- rifabutin (Ansamycin), clofazimine, and fluoroquinolones.
A photochromogen that requires complex media for growth at 37°C
M kansasii
It can produce pulmonary and systemic disease indistinguishable from tuberculosis, especially in patients with impaired immune responses.
M kansasii
M kansasii is sensitive to
RMP, it is treated with the combination of RMP, EMB, and INH with a good clinical response.
A scotochromogen occasionally found in water and as a saprophyte in adults with chronic lung disease.
Mycobacterium scrofulaceum
Mycobacterium scrofulaceum causes ______ lymphadenitis in children and, rarely, other granulomatous disease.
chronic cervical
Surgical excision of involved cervical lymph nodes may be curative, and resistance to antituberculosis drugs is common to treat.
Mycobacterium scrofulaceum
These organisms occur in water, grow best at low temperature (31°C), may infect fish, and can produce superficial skin lesions (ulcers, “swimming pool granulomas”) in humans.
Mycobacterium marinum
Mycobacterium ulcerans
Treatment for Mycobacterium marinum and Mycobacterium ulcerans
Surgical excision, tetracyclines, RMP, and EMB are sometimes effective
These are saprophytes found in soil and water that grow rapidly (3–6 days) in culture and form no pigment. They can produce superficial and systemic disease in humans on rare occasions.
Mycobacterium fortuitum Complex
Treatment for Mycobacterium fortuitum Complex
amikacin doxycycline cefoxitin erythromycin RMP.
Both species are capable of causing skin, so tissue, and bone infections after trauma or surgery, which can disseminate in immunocompromised patients.
Mycobacterium chelonae
Mycobacterium abscessus
Also frequently recovered from patients with respiratory disease in the United States, especially in south-eastern regions.
The individuals most commonly infected are elderly, white, female nonsmokers
Mycobacterium abscessus
Is typically susceptible to tobramycin, clarithromycin, linezolid, and imipenem.
Mycobacterium chelonae
Are usually used for treatment of M abscessus, although drug resistance is a major problem with this organism
Clarithromycin, amikacin, and cefoxitin
Causes a pulmonary tuberculosis-like disease in adults and lymphadenitis in children.
Mycobacterium malmoense
Cause disease in patients with AIDS
Mycobacterium haemophilum and Mycobacterium genavense
Current recommendations for prevention of leprosy include a
thorough examination of household contacts and close relatives.
Does provide some protection against leprosy especially among household contacts of cases.
BCG
Transmission of this is most likely to occur when small children are exposed for prolonged periods to heavy shedders of bacilli.
leprosy
Are the most likely infectious material for family contacts.
Nasal secretions
The incubation period of M leprea is
2–10 years
Are first-line therapy for both tuberculoid and lepromatous leprosy.
Sulfones such as dapsone
RMP and/or clofazimine generally are included in the initial treatment regimens.
Scrapings with a scalpel blade from skin or nasal mucosa or from a biopsy of earlobe skin are smeared on a slide and stained by the
Ziehl-Neelsen technique.
Nontreponemal serologic tests for syphilis frequently yield ______ results in patients with leprosy
false-positive
The skin lesions of this bacteria may occur as pale, anesthetic macular lesions 1–10 cm in diameter; diffuse or discrete erythematous, infiltrated nodules 1–5 cm in diameter; or a diffuse skin infiltration.
M leprea
Neurologic disturbances are manifested by nerve infiltration and thickening, with resultant anesthesia, neuritis, paresthesia, trophic ulcers, and bone resorption and shortening of the digits.
M leprea
The disease leprosy is divided into two major types:
Lepromatous
Tuberculoid
In the lepromatous type, the course is _______, with nodular skin lesions; ________ nerve involvement; abundant acid-fast bacilli in the skin lesions; ______ bacteremia; and a ______ lepromin (extract of lepromatous tissue) skin test result.
- progressive and malignant
- slow, symmetric
- continuous
- negative
In the tuberculoid type, the course is ______, with a ______ of macular skin lesions containing few bacilli, ______ nerve involvement of sudden onset, and a _____ lepromin skin test result.
- benign and nonprogressive
- small number
- severe asymmetric
- positive
Involvement of this organ is common in leprosy
Eye
Involvement of this organ is common in leprosy
Eye
Typical acid-fast bacilli—singly, in parallel bundles, or in globular masses—are regularly found in scrapings from skin or mucous membranes (particularly the nasal septum) in patients with lepromatous leprosy.
M leprea
When bacilli from human leprosy (ground tissue nasal scrapings) are inoculated into the footpads of mice, _______ with limited multiplication of bacilli.
local granulomatous lesions develop
They develop extensive lepromatous leprosy.
Inoculated armadillos
M leprae from armadillo or human tissue contains a unique enzyme that is a characteristic of leprosy bacilli.
o-diphenoloxidase
