Mycobacterial Infections

Question 1

Tuberculosis

Answer 1

Aerobic, nonspore forming, nonmotile, gram-positive bacteria

Spread through the air from one person to another when bacteria are aerosolized from a person with pulmonary TB

Question 2

TB risk factors

Answer 2

Close contacts of a person with infectious TB disease.
Children < 5 years old who have a positive tuberculin skin test

Persons who have immigrated from regions of the world with high rates of TB

Groups with high rates of TB transmission including persons with HIV infection, injection drug users, and homeless persons

Working or residing with people at high risk for TB in facilities or institutions

Medical conditions that weaken the immune system such as HIV infection, treatment with immunosuppressive medications, diabetes, malignancy, organ transplantation, silicosis, substance abuse disorder, severe kidney disease, or low body weight.

Question 3

Symptoms of TB

Answer 3

Fever
Fatigue
Weight loss
Night sweats
Cough
Hemoptysis (cough blood)

Question 4

TB diagnosis

Answer 4

Identification ofMycobacterium tuberculosisin respiratory specimen confirms diagnosisof pulmonary TB in patients with compatible clinical symptoms

Acid fast bacillus smear microscopy

Nucleic Acid Amplification Testing

(sample collected from sputum, hack it up)
(or go into the lungs with a tube)

Question 5

Management of TB

Answer 5

Patients should be placed in Airborne infection isolation with appropriate infection control measures for providers and visitors

Report to local health authorities

Question 6

Treatment of TB

Answer 6

2 month initial phase of treatment:
Isoniazid, Rifampin, Pyrazinamide, plus Ethambutol

Followed by a 4 month continuation phase:
Isoniazid and rifampin

Question 7

Latent TB infection

Answer 7

in the absence of clinical disease, latent TB is detected by presence of an immune response to M. tuberculosis antigens

1/4 of the world’s population has latent TB

Question 7

Latent TB infection

Answer 7

in the absence of clinical disease, latent TB is detected by presence of an immune response to M. tuberculosis antigens

1/4 of the world’s population has latent TB (not actively contagious)

Question 8

Latent TB cont.

Answer 8

-Testing is routinely performed in at-risk population
-Tuberculin skin test (TST): Injected M. Tuberculosis purified protein derivative (PPD)
-Quantiferon (ELISA) test: measures plasma concentration of interferon gamma after stimulation with M. tuberculosis peptides
-Positive tests need to be evaluated with a review of symptoms (if any) and chest x-ray

Question 9

Latent TB Treatment

Answer 9

Isoniazid
Rifampicin

Question 10

NOTE:

Answer 10

TB can impact areas other than the lungs, and he wants us to be familiar with it and get tested on it

what makes it stand out as TB opposed to something else when elsewhere in the body?

Question 11

Nontuberculous mycobacterial diseases!!!

Answer 11

Do not cause TB, but do cause respiratory issues and resemble TB

May Cause:
Pulmonary Infections
Lymphadenitis
Skin & Soft Tissue Infections
Disseminated Mycobacterium Avium Infection

Question 12

Nontuberculous mycobacterial diseases cont.

Answer 12

Pulmonary Infections:

Mycobacterium avium complex (MAC)
-Causes a chronic, slowly progressive pulmonary infection resembling tuberculosis
-Immunocompetent patients
-With Underlying pulmonary disease
-Susceptibility testing for macrolide-resistance should be performed on clinical isolates
-Sputum culture
-Bronchioalveolar lavage
-Pulmonary disease is often classified as nodular, bronchiectatic, or fibrocavitary.

Question 13

Other non TB mycobacterial diseases:

Answer 13

Pulmonary Infections
-M kansasii
-Can resemble tuberculosis
-But illness progresses more slowly
-In patients with preexisting lung disease 60% of the
time
-Sensitive to the same drugs as M tuberculosis except
pyrazinamide

Question 14

Know:

Answer 14

There are more mycobacteria than just TB

Question 15

Non TB myco: Lymphadenitis

Answer 15

Most cases in adults caused by M tuberculosis in disseminated disease

In children, the majority of cases are due to nontuberculous mycobacterial species:
-MAC being the most common

Question 16

lymphadenitis treatment

Answer 16

surgical excision of infected lymph node

(antituberculosis therapy not needed)

Question 17

Non TB Myco:

Answer 17

Skin & Soft Tissue Infection
-Abscesses
-Septic arthritis
-Osteomyelitis
Can result from direct inoculation
Or hematogenous dissemination from surgery
-Ex. Removal of infected lymph node above

Question 18

Treatment of skin and soft tissue infection

Answer 18

Surgical debridement (cut out) along with at least two active antibiotics
-Resistant to antituberculosis drugs
-Obtain antibiotic susceptibility testing
-Antibiotic therapy for 3 months

Question 19

Swimming pool granuloma

Answer 19

nodular skin lesion following exposure to non-chlorinated water

Question 20

Buruli ulcer

Answer 20

Mainly in Africa and Australia (test specific)

large ulcerative lesion

therapy consists of surgical excision and skin grafting

Question 21

Still Non TB myco diseases: MAC infection

Answer 21

-Immunocompromised patients
-AIDS patients with CD4+ cell count <50/mcL
-Persistent fever
-Weight loss are the most common symptoms
-MAC can be cultured from multiple sites:
-Blood, liver, lymph node, or bone marrow.
-Blood culture is the preferred means of establishing the diagnosis and has a sensitivity of 98%.

Question 22

Treatment of MAC infection:

Answer 22

Clarithromycin
Plus ethambutol
With or without rifabutin
Therapy may be discontinued after 12 months if:
no evidence of active disease,
CD4 counts >100/mcL for 6 months while receiving antiretroviral therapy

Question 23

MAC prophylaxis

Answer 23

-Prevents disseminated disease and prolongs survival
-Standard of care in all patients with HIV infection and CD4 counts ≤50/mcL
-Single-drug oral regimens suffice

(Mentioned something about knowing prophylaxis, maybe take more detailed notes)