157 - Tuberculosis and Infections with Atypical Mycobacteria Flashcards by dvojnd rivera

Main cause of death in patients infected with HIV

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Highest burden of TB in the following countries

India
Indonesia
China
Philippines
Pakistan

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In contrast to the obligate pathogens, _____ pathogens do not cause disease by person-to-person spread

Facultative

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2 most frequent forms of skin tuberculosis

Lupus vulgaris

Scrofuloderma

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In the tropics, LV is rare, wherease _____ lesions predominate

Scrofuloderma

Tuberculosis verrucosa cutis

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Exogenous infection with naive host immune status

Primary inoculation tuberculosis

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Exogenous infection with immune host status

Tuberculosis verrucosa cutis

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Endogenous spread with high host immune status

Lupus vulgaris

Scrofuloderma

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Endogenous spread with low host immune status

Acute miliary tuberculosis
Orificial tuberculosis
Metastatic tuberculous abscess (tuberculous gumma)

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Tuberculosis caused by bacille Calmette-Guerin

Normal primary complex-like reaction
Perforating regional adenitis
Postvaccination lupus vulgaris

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Tuberculids: conditions in which Mycobacterium tuberculosis/Mycobacterium bovis appears to play a significant role

Lichen scrofulosum

Papulonecrotic tuberculid

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Facultative tuberculids: conditions in which M. tuberculosis/M. bovis may be one of several pathogenic factors

Nodular vasculitis/erythema induratum of Bazin

Erythema nodosum

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Most common cause of disseminated bacterial infection in patients with AIDS

Mycobacterium avium-intracellulare complex

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In AIDS patients, Mycobacterium _____ is more common than M. tuberculosis

kansasii

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Cutaneous disease in AIDS is frequently caused by Mycobacterium _____

Other than Mycobacterium tuberculosis

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A large number of bacteria can be found in the lesions of

Primary chancre

Acute miliary tuberculosis

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Delayed-type hypersensitivity reaction induced by mycobacteria during primary infection

Tuberculin reaction (Koch phenomenon)

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Maximum intensity of tuberculin reaction after

48 hours

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QuantiFERON-TB Gold test measures specific antigen-driven _____ synthesis

Interferon-gamma

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Tuberculin sensitivity usually develops _____ after infection and persists throughout life

2 to 10 weeks

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In patients with clinical tuberculosis, an increase in skin sensitivity usually indicates a (favorable/poor) prognosis

Favorable

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In tuberculous skin disease accompanied by high levels of skin sensitivity, the number of bacteria within the lesions is (small/large)

Small

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Although more sensitive than the tuberculin skin test, _____ may be negative in patients with early active tuberculosis and indeterminate results are more common in immunocompromised individuals and young children

QFT-G

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Measures the IFN-gamma producing T cells

T-SPOT TB test

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Procedure that has been used to ascertain the presence of mycobacterial DNA in skin specimens

Polymerase chain reaction

PCR showed _____% sensitivity in multibacillary disease. In paucibacillary disease, PCR testing showed _____% sensitivity and specificity

100 | 55

Multidrug resistant TB is defined as

Resistance to at least rifampicin and isoniazid

Regimen for extrapulmonary tuberculosis

Initial Phase INH, RIF, PZA, EMB 7 days per week for 56 doses (8 weeks) or 5 days per week for 40 doses (8 weeks) Continuation Phase INH/RIF 7 days per week for 128 doses (18 weeks) or 5 days per week for 90 doses (18 weeks)

Doses of medications (maximum dose) when given daily

EMB 18 mg/kg (1600 mg) INH 5 mg/kg (300 mg) PZA 25 mg/kg (2000 mg) RIF 10 mg/kg

Tuberculosis verrucosa cutis and localized forms of LV without evidence of associated internal tuberculosis may be treated with

Isoniazid alone for up to 12 months

Because viable mycobacteria have been found in clinically healed lesions, treatment should be continued for at least _____ after complete involution of the lesion

2 months

Extensively multidrug-resistant TB is defined as

Resistance to at least rifampicin and isoniazid in addition to resistance to any fluoroquinolone, and to at least 1 of the 3 injectable second-line anti-TB drugs (capreomycin, kanamycin, and amikacin)

Tuberculous chancre and affected regional lymph nodes constitute the

Tuberculous primary complex

Most often affected with primary inoculation tuberculosis

Children

Primary inoculation tuberculosis is initially (paucibacillary/multibacillary)

Multibacillary, but becomes paucibacillary as immunity develops

PPD reaction finding in primary inoculation tuberculosis

Negative initially and later converts to positive

Paucibacillary disorder caused by exogenous reinfection (inoculation) in previously sensitized individuals with high immunity

Tuberculosis verrucosa cutis

Extremely chronic, progressive form of cutaneous tuberculosis occurring in individuals with moderate immunity and a high degree of tuberculin sensitivity

Lupus vulgaris

(Males/Females) are appear to be more commonly affected in lupus vulgaris

Females

In approximately 90% of patients, the _____ are involved in LV

Head and neck

After a transient impairment of immunity, particularly after measles, multiple disseminated lesions may arise simultaneously in different regions of the body as a consequence of hematogenous spread from a latent tuberculous focus

Lupus postexanthematicus

Often the only symptom of early nasal LV

Dry rhinitis

Longstanding LV may lead to the development of

SCC

Subcutaneous tuberculosis leading to cold abscess and a secondary breakdown of the overlying skin

Scrofuloderma

Scrofuloderma prevalence is higher among

Children, adolescents, and the aged

Scrofuloderma most often occurs in the _____ regions

Parotideal, submandibular, supraclavicular

Y/N: In scrofuloderma, tuberculin sensitivity is usually pronounced

Yes

Rare form of tuberculosis of the mucous membranes and orifices that is caused by autoinoculation of mycobacteria from progressive tuberculosis of internal organs

Orificial tuberculosis

Most frequently affected in orificial tuberculosis

Tongue

Y/N: Orificial tuberculosis is a symptom of advanced internal disease and usually portends a fatal outcome

Yes

In the normal course of BCG vaccination, an infiltrated papule develops after approximately _____, ulcerates, and then slowly heals, leaving a scar

2 weeks

Tuberculin sensitivity appears _____ after vaccination

5 to 6 weeks

Y/N: Antituberculosis drugs are beneficial in all cases of tuberculids

No - beneficial in some cases but not all

Uncommon lichenoid eruption ascribed to hematogenous spread of mycobacteria in an individual strongly sensitive to M. tuberculosis

Lichen scrofulosorum

Lichen scrofulosorum lesions are usually confined to the

Trunk

Lichen scrofulosorum occur most often in

Children and adolescents with active tuberculosis

Symmetric eruption of necrotizing papules, appearing in crops and healing with scar formation

Papulonecrotic tuberculid

Papulonecrotic tuberculid occurs preferentially in

Children or young adults

Sites of predilection of papulonecrotic tuberculid

Extensor aspects of the extremities, buttocks, and lower trunk

Atypical mycobacteria are usually acquired from

Environmental sources such as water or soil

Y/N: MOTT seem more likely to disseminate than M. tuberculosis, and infections usually run a more aggressive and chronic course

No - less likely to disseminate; more benign and limited course

Y/N: MOTT are much less responsive to antituberculosis drugs

Yes

MOTT that affects skin, subcutis, lymph nodes and other organs

Mycobacterium kansasii | Mycobacterium avium-intracellulare complex (including Mycobacterium scrofulaceum)

Only 2 MOTT produce a characteristic clinical picture

M. ulcerans | M. marinuum

Third most frequent mycobacterial pathogen, after M. tuberculosis and M. lepra

M. ulcerans

M. ulcerans causes

Buruli ulcer disease

Buruli ulcer disease is found most often in

Children and young adults | Females more often than males

Y/N: Buruli ulcer disease is deeply undermined, and necrotic fat is exposed. The preceding nodule, as well as the ulcer, is painless

Yes

The painless nature of Buruli ulcer disease has been attributed to nerve damage and tissue destruction caused by the toxin

Mycolactone

Occurs in freshwater and saltwater, including swimming polls and fish tanks

Mycobacterium marinum infection

Atypical Mycobacterium most closely related to M. tuberculosis

Mycobacterium kansasii

Skin disease caused by M. kansasii usually occurs in

Adults, and is more common in individuals with underlying immunosuppression

Most commonly affected organ by M. kansasii

Lung

Usual manifestation is cervical lymphadenitis, frequently unilateral, in children, mainly between the ages of 1 and 3 years

Mycobacterium scrofulaceum infection

Lymph nodes typically involved in Mycobacterium scrofulaceum infection

Submandibular | Submaxillary

M. scrofulaceum is usually grouped together with

Mycobacterium-avium intracellulare

Whereas M. scrofulaceum produces only a benign, self-limited lymphadenopathy with no organ involvement, M. avium-intracellulare infection usually causes

Lung disease or, less frequently, osteomyelitis

3 species of fast-growing, facultative pathogenic mycobacteria

M. fortuitum M. chelonae M. abscessus