Tuberculosis

____ epidemic is considered a major risk factor for opening the door for active TB infection

AIDS

Factors that contribute to the emergence of TB?

Epidemic proportions of TB among HIV patients, emergence of multi-drug resistant strains of M. Tuberculosis

Tuberculosis is an infectious disease transmitted by

Mycobacterium tuberculosis

Tuberculosis is spread by

coughing, sneezing, laughing or __? (Airborne)

TB usually involves the lungs but also occurs in

kidneys, bones, lymph nodes, and meninges

3 strains of Mycobacterium tuberculosis that affect man

human, Avian (bird), Bovine (cows)

MDR-TB strains developed due to

poor vigilance in treating TB clients, poor compliance w/ drug therapy, patients lost in FU tx, drug regimens that infections are not susceptible to anymore

Who are at risk for TB?

poor, underserved and minorities; homeless, socio-economically disadvantaged, residents of inner city neighborhoods, foreign-born persons, older adults in LTC, injection drug users, medically underserved in all races

M. Tuberculosis is a gram _____ acid-fast bacilli

negative

TB transmission requires

close (w/in 6 inchest of person's mouth), frequent, and/or prolonged exposure

TB cannot be spread by

hands, books, glasses or dishes

TB infection

small droplet remains airborne for minutes to hours until inhaled, deposits in alveoli, replicates slowly and spreads to lymphatic system, cellular immunity limits further multiplication and spreads to infection, after cellular immune system is activated

Favorable environment for TB

upper lobes of lungs, kidneys, epiphyses of bones, cerebral cortex, and adrenal glands

____ can be seen on x-ray

Pockets of infection

Will have a positive skin test ___ post exposure

2-10 weeks

Durimg the 2-10 weeks post exposure can you spread to others?

no

Reactivation of latent TB can occur with

impaired host defense mechanisms, elderly, concomitant disease, immunosuppresant therapy (long-term corticosteroid use, diabetics)

Classification of TB

Class 0 - No TB exposure
Class 1 - TB exposure, no infection
Class 2 - Latent TB infection, no disease
Class 3 - TB clinically active
Class 4 - TB, but no clinically active
Class 5 - TB suspect

S/S of early stages of TB

usually no symptoms

S/S of latent TB

positive skin test but no symptoms

S/S of active TB

fatigue, malaise, anorexia, unexplained weight loss, low-grade fever, night sweats, cough that becomes frequent and produces white frothy sputum

Active TB with acute sx

high fever, chills, generalized flu-like sx, pleuritic pain, productive cough

HIV-infected w/ TB symptoms

atypical exam and cxray findings, weight loss, fever and cough

Complications of TB

military TB - either acute or chronic systemic problems, pleural effusion, empyema, TB pneumonia, CNS problems (confusion, HA, back pain, disorientation

What is the TB skin test called

Mantoux test

Positive TB reaction occurs

2-12 weeks after exposure

A positive TB reaction indicates

the individual has been infected and has developed sensitivity to the protein of the Tubercle Bacillus--does not confirm presence of actual disease-only few with positive TB will ever develop active TB

Guidelines for PPDs

Must be checked after 48-72 hours (2-3 days) ***need to look up, can't read the slide ;-) be back soon

Other diagnostic tests for TB

Chest x-ray - upper lobe infiltrates and lymph nodes
Bacteriologic studies - sputum smear, sputum culture, QuantiFERON-TB (QFT)

Sputum smear as diagnostic test for TB

microscopic exam for acid-fast bacilli (AFB tests) --need >10,000 bacteria/mL to produce a positive smear

Sputum culture as a diagnostic test for TB

most accurate means of dx, BUT takes up to 8 weeks for culture to grow

QuantiFERON-TB as a diagnostic test for TB

Serum placed in chambers in mycobacterial antigens - if positive takes only a few hours

Drug therapy for TB

Long-term tx with antimicrobials, FU bacteriologic studies and chest x-rays

Drug therapy for active TB

isoniazid (INH) - but many are resistant to this; rifampin (Rifadin)
pyrazinamide (PZA); ethambutol *
combo therapy best
*
Others: fluroquinolones, levofloxacin, moxifloxacin, gatifloxacin, steptomycin, kanamycin

Problems w/ TB drug therapy

Length of time meds must be taken, short course 6-9 months, Dev of severe liver disease, FU evals, compliance, side effects,

Latent TB infection

infection is present but not active, drug therapy administered to prevent TB infection dev into clinical disease in some cases

Drug of choice for latent TB infection

INH (isoniazid) - short course is 6-9 months; 9-month course more effective but lower compliance

What is the vaccine to prevent TB?

bacille Calmette0Guerin (BCG)

Precautions for patients with TB who are hospitalized

Place in respiratory isolation (HEPA masks), give appropriate drug therapy, immediate medical workup of sputum smear, culture and chest x-ray

How long are they isolated?

Isolated in negative pressure airflow room with 6-12 exchanges per hour. Must be there until 3 negative AFB smears