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Flashcards in tb intro Deck (15):

1st line agents for TB

Isoniazid (NydrazidR)
Ethambutol (Myambutol)
Rifampin (RimactaneR, Rifadin)


risk for reactivation of latent tb w. these agents??

anti-TNF agents, i.e. infliximab


tb tx requires ??

-two or more drugs to which the tubercle organisms are susceptible
-must continue 3-6 mos after the sputum becomes negative to sterilize the lesions and prevent relapse


Tubercle bacilli are killed by antituberculosis drugs only during ??

-obligate aerobe


Several populations of tubercle bacilli are hypothesized to exist in the host:

-cavitary lesions: O2 tension is high, medium is neutral or slightly alkaline and multiplication active;
- in closed caseous lesions: O2 tension is low, medium is neutral and replication is slow and intermittent
-w.in macrophages: intracellular miliew is acidic and multiplication is relatively slow.


table 1

actively multiplying: alveoli
acid pH: macrophages
neutral pH: only INH, rifampin work


resistance to INH is ?? in the US

increasing (native-born)


Active Disease Treatment

*Isoniazid* should be used (in conjunction with other drugs) for the duration of therapy because of its efficacy, low cost, and tolerability.
-If rifampin is not used, 18 months is the minimal duration of therapy associated with acceptable rates of cure.
-the absence of drug resistance, a regimen of isoniazid and rifampin administered for 9 months is curative.


addition of ?? for the first 2 months of treatment allows the regimen to be shortened to 6 months and is associated with improved compliance and cure rates.



Short-Course Chemotherapy

6 and 9-month:
-initial phase with isoniazid, rifampin, pyrazinamide and ethambutol administered daily for 2 months,
-followed by a continuation phase consisting of isoniazid and rifampin given daily, twice a week, or three times a week for 4 months
(4 for 2, 2 for 4)


Direct observation of therapy (DOT)

encourage patients to complete therapy w. incentives


A ?? should be obtained at the beginning of treatment to help establish the diagnosis

chest radiograph
-should also be obtained at the end of treatment as a base line for future reference.


For culture-negative cases of tuberculosis, the response to therapy is monitored by ?? at three months.

reviewing symptoms and obtaining a chest radiograph


To prevent infection in an individual with a negative Mantoux skin test in the absence of anergy who has had intimate contact with an active case.??

2 months of daily treatment with rifampin and pyrazinamide is an effective alternative treatment to isoniazid.


HIV-infected persons

6-month chemotherapy. Isoniazid, rifampin and pyrazinamide are given daily for 2 months and if there is no resistance to either isoniazid or rifampin, treatment is continued with only the latter drugs for an additional 7 months or at least another 6 months following 3 negative cultures. Ethambutol is added to the regimen for patients with CNS involvement or disseminated tuberculosis or when resistance to isoniazid is suspected.