Mycobacterial Infections Flashcards
Tuberculosis
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
TB risk factors
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.
Symptoms of TB
Fever
Fatigue
Weight loss
Night sweats
Cough
Hemoptysis (cough blood)
TB diagnosis
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)
Management of TB
Patients should be placed in Airborne infection isolation with appropriate infection control measures for providers and visitors
Report to local health authorities
Treatment of TB
2 month initial phase of treatment:
Isoniazid, Rifampin, Pyrazinamide, plus Ethambutol
Followed by a 4 month continuation phase:
Isoniazid and rifampin
Latent TB infection
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
Latent TB infection
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)
Latent TB cont.
-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
Latent TB Treatment
Isoniazid
Rifampicin
NOTE:
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?
Nontuberculous mycobacterial diseases!!!
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
Nontuberculous mycobacterial diseases cont.
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.
Other non TB mycobacterial diseases:
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
Know:
There are more mycobacteria than just TB
Non TB myco: Lymphadenitis
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
lymphadenitis treatment
surgical excision of infected lymph node
(antituberculosis therapy not needed)
Non TB Myco:
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
Treatment of skin and soft tissue infection
Surgical debridement (cut out) along with at least two active antibiotics
-Resistant to antituberculosis drugs
-Obtain antibiotic susceptibility testing
-Antibiotic therapy for 3 months
Swimming pool granuloma
nodular skin lesion following exposure to non-chlorinated water
Buruli ulcer
Mainly in Africa and Australia (test specific)
large ulcerative lesion
therapy consists of surgical excision and skin grafting
Still Non TB myco diseases: MAC infection
-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%.
Treatment of MAC infection:
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
MAC prophylaxis
-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)
