Infectious Lung Diseases (TB, flu, etc) Flashcards
Who should get a flu vaccine?
Anyone 6 months or older who does not have a contraindication.
When should we start administering flu vaccines?
Before flu activity starts in the community: preferably October if possible
What group might require 2 vaccines?
Children between the ages of 6 months & 8 years who are being vaccinated for the first time.
At what type of visit should providers offer the flu vaccine?
At EVERY visit: office visit, hospital, etc.
Which is more effective in adults: live attenuated virus or inactivated virus vaccine?
Both are equally effective in adults.
Which is more effective in children: live attenuated virus or inactivated virus vaccine?
Live attenuated virus (flu mist)
According to the CDC website: “When immediately available, LAIV should be used for healthy children aged 2 through 8 years who have no contraindications or precautions (Category A). If LAIV is not immediately available, IIV should be used.”
Which is convenient so you don’t have to chase a kid around to give them a shot. :)
The live attenuated flu virus should not be used in the following populations:
1) Persons aged 49 years;
2) Children aged 2 through 17 years who are receiving aspirin or aspirin-containing products;
3) Persons who have experienced severe allergic reactions to the vaccine or components;
4) Pregnant women;
5) Immunosuppressed persons;
6) Persons with a history of egg allergy;
7) Children aged 2 through 4 years who have asthma or who have had a wheezing episode within the past 12 months
8) Persons who have taken influenza antiviral medications within the previous 48 hours.
What is tuberculosis?
Disease caused by bacteria of the Mycobacterium tuberculosis complex.
Usually affects the lungs but other organs can be involved in up to 1/3 of cases.
Description of M. tuberculosis bacterium
#rod-shaped #non spore-forming #aerobic #acid fast
What does it mean for a bacterium to be acid-fast?
Once stained via Gram-staining, it cannot be decolorized with acid alcohol
When a bacterium is acid-fast, what does that mean for antibiotic therapy?
Cell wall is not very permeable, rendering antibiotics less effective
Of the new cases of TB reported to the World Health Organization in 2009, where were most located?
95% of them in the developing nations of Asia, Africa, Middle East, & Latin America.
How is TB transmitted?
Droplets from a person with infectious pulmonary TB are aerosolized by coughing, sneezing, speaking. Remain suspended in air for several hours & are inhaled by others.
Important determinants of likelihood of transmission
1) Probability of contact with infectious TB patient
2) Intimacy & duration of that contact
3) Degree of infectiousness of the case
4) Shared environment where contact happens
What TB patient is most likely to transmit infection?
Those who sputum contains AFB visible by microscopy
One of the most important factors in the transmission of TB is…
Overcrowding in poorly ventilated rooms (which makes sense with the developing nations TB problem)
What is the “Ghon focus” in the context of TB?
Lung lesion forming after initial infection
Lobes most commonly involved in primary TB
Middle & lower lung zones
Primary TB may quickly progress to clinical illness in what populations?
1) Children
2) Immunocompromised
Post-primary TB or “adult-type” TB can result from either
1) Endogenous reactivation of distant, latent infection
2) Recent infection
Adult-type TB localizes to…
the apical & posterior upper lung segments, where high O2 tension favors bacterial growth
With cavity formation in the lung parenchyma, what happens to the spread of TB in the lung?
Liquified necrotic contents of the cavities are discharged into the airways & undergo bronchogenic spread, resulting in more lesions that could undergo cavitation
Up to 1/3 of untreated TB patients with post-primary disease…
…succumb to severe pulmonary TB within a few months. In the Olden Days this was called “galloping consumption”. Bonus points if you write that in a chart.
Other patients undergo a spontaneous remission…
…and have a more chronic course. This was just “consumption” in the Olden Days. Doc Holliday had it!
When TB is on the differential, how do we diagnose?
1) AFB microscopy
2) Mycobacterial culture
3) Nucleic acid amplification
High points of AFB microscopy for TB
1) Relatively low sensitivity
2) 2-3 sputum specimens, preferably from early morning collection
How long does it take to culture TB?
4-8 weeks
How long does nucleic acid amplification for TB take us?
Diagnosis in just a few hours, with high specificity & sensitivity approaching that of culture.
High points of radiography for TB
1) Initial suspicion for TB is usually based on the CXR of a patient with respiratory sx
2) Classic picture: upper-lobe disease with infiltrates & cavities
3) Virtually ANY CXR pattern may show up, though
What’s the PPD skin test?
Subcutaneous injection of “tuberculin purified protein derivative”, which is widley used in screening for latent TB infection.
It’s unable to discriminate between active vs. latent disease.
PPD false negatives? False positives?
#False negative: Immunosuppressed patients, patients with overwhelming TB #False positive: infections with non-TB mycobacteria, BCG vaccination (a TB vaccine)
Two goals of TB therapy
1) Interrupt transmission by rendering patients noninfectious
2) Prevent morbidity & death by curing patients while preventing drug resistance
Well don’t WE just have lofty goals?
Though standard therapy is 3 drugs, there are 4 drugs considered 1st-line agents. They are:
1) Isoniazid
2) Rifampin
3) Pyrazinamide
4) Ethambutol
The 4 first line TB agents are recommended based on what properties?
1) Bactericidal activity
2) Sterilizing activity
3) Low rate of induction of drug resistance
Some 2nd-line drugs, used only in patients refractory to 1st-line agents:
1) Injectable aminoglycosides (streptomycin, kanamycin, amikacin)
2) Injectable polypeptide capreomycin
3) Oral agents (ethionamide, cycloserine, PAS)
4) Fluoroquinolone antibiotics (levofloxacin, moxifloxacin)
Standard short-course therapy for TB is divided into 2 stages. What are they & what do they do?
1) Initial: bactericidal. KILL IT WITH FIRE. Kill the majority of the bacteria, resolve symptoms, patient becomes noninfectious.
2) Continuation: sterilization. PUT OUT THE HOT SPOTS. Eliminate persisting bacteria, prevent relapse.
Standard therapy for virtually all forms of adult TB
2 month initial phase: isoniazid, rifampin, pyrazinamide, & ethambutol
4 month continuation phase: isoniazid & rifampin
Who is at high-risk for isoniazid-related neuropathy? What do we give to prevent it?
Ppl with B6 deficiency: alcoholics, malnourished perople, pregnant & lactating women, patients with renal failure, diabetes, or HIV
Give pyridoxine (10-25 mg daily) to prevent
Most important impediment to TB cure worldwide is…
…lack of adherence to treatment!
TAKE YOUR MEDS, PEOPLE. WORK WITH ME HERE.
What is likely to happen to the bacteria infecting non-adherent patients?
Drug resistance!
CONGRATULATIONS, JERK.
Patient-related factors affecting compliance
1) Lack of belief that illness is significant
2) Lack of trust in treatment
3) Existence of comorbidities or conditions (substance abuse)
4) Lack of social support
5) Poverty
Provider-related factors improving compliance
1) Education & encouragement
2) Convenient hours
3) Provisions of incentives like meals or travel vouchers
4) Direct observation of treatment
5) Provision of fixed-drug combo products
Monitoring for TB therapy response:
1) Sputum examined monthly until cultures are negative
2) With recommended regimen, 80% have negative sputum cultures by end of 2nd month
3) By 3rd month, virtually ALL patients should be negative
Patients with cavitary disease & positive sputum culture by the end of 2 months require…
…extended treatment
If sputum culture is still positive by ≥ 3 months of treatment, suspect:
1) Treatment failure & drug resistance or
2) Poor adherence to therapy
Is a CXR useful at the end of TB treatment?
Yes, but not for diagnosis of cure. It may be useful for comparative purposes should the patient later develop recurrent symptoms months or years later.
The high points of monitoring patients for drug toxicity in TB treatment
1) Most common adverse reaction: hepatitis
2) Educate patients about sx; discontinue treatment & see provider promptly
3) Baseline liver function tests for everyone before treatment (YOU get LFTs! YOU get LFTs! EVERYONE gets LFTs!)
4) Monthly monitoring in: older patients, hx of hepatic disease, daily alcohol users, & the immunosuppressed.
Is the BCG TB vaccine recommended for general use in the US? Why or why not?
No, because of
1) low risk of transmission in US
2) Unreliability of vaccine
3) Impact on the TB skin test
Reading a PPD: Size considered positive for different groups
HIV-infected or immunosuppressed: ≥ 5mm Close contacts of TB patient: ≥ 5mm Fibrotic lesions on CXR: ≥ 5mm Ppl infected ≤ 2 yrs: ≥ 10mm Ppl w/ high risk conditions: ≥ 10mm Low risk ppl: ≥ 15mm
