tb intro

Question 1

1st line agents for TB

Answer 1

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

Question 2

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

Answer 2

anti-TNF agents, i.e. infliximab

Question 3

tb tx requires ??

Answer 3

• 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

Question 4

Tubercle bacilli are killed by antituberculosis drugs only during ??

Answer 4

replication

-obligate aerobe

Question 5

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

Answer 5

• 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.

Question 6

table 1

Answer 6

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

Question 7

resistance to INH is ?? in the US

Answer 7

increasing (native-born)

Question 8

Active Disease Treatment

Answer 8

• 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.

Question 9

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.

Answer 9

pyrazinamide

Question 10

Short-Course Chemotherapy

Answer 10

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)

Question 11

Direct observation of therapy (DOT)

Answer 11

encourage patients to complete therapy w. incentives

Question 12

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

Answer 12

chest radiograph

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

Question 13

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

Answer 13

reviewing symptoms and obtaining a chest radiograph

Question 14

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.??

Answer 14

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

Question 15

HIV-infected persons

Answer 15

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.