Infectious Lung Diseases: TB, Pertussis, Croup, Epiglottitis Flashcards
Tuberculosis
TB Infection v. TB Disease
- TB Infection:
- Eaiser to treat than Dz
- People can get this with NO presentation
- Infection….Latency… Disease!
- Disease:
- Bacteria overcome the Immune System, mutiply & progress from latent infection to DISEASE
- Some symptoms:
- Weight loss, Loss of Appetite, Fatigue, Chills, Fever
TB
A Quick History
- Has affected humans for millennia
- Historic names:
- Consumption
- Wasting Disease
- White Plague
- Used to cause many deaths, not well-controlled
- Before 1800’s, thought was hereditary
- 1882- R. Koch disovered M. tuberculosis
TB
Sanatoriums
- Before Abx, many sent to locations where they were isolated
- Provided with: open air, bed rest, sunshine
- Lots of people could not afford this
- 70-75% fatalities in the “olden days”
- As drugs were created, death rates dropped
- Sanatoriums closed by mid-1970’s
TB
Drugs created in the 1940’s & 50’s
- 1943: Streptomycin
- 1943-1952:
- Isonizaid (INH)*
- p-aminosalicylic acid (PAS)
*Same drug formula used today!!
TB
Why was there a resurgence in 1980’s?
- Inadequate funding
- HIV epidemic
- Increase immigration from countries were TB is common
- Spread in close-quarters (shelters)
- Multi-drug resistant TB increase and spread
*Still a global issue!
TB
Epidemiology
‘The study of the distribution & causes of disease and other health problems in different groups of people”
- One of the leading causes of death due to infectious disease in the world
- ~2 Billion people are Infected!
- About 9 million people develop TB/year
– About 2 million people die of TB/year
TB
Trend in the U.S.
- Before 1953, more than 84,000 cases in US
- Declined by 6%/year after 1953
- Reached a low in 1985, but then picked up again in 1986…
TB
Transmission
“Transmission is defined as the spread of an organism, such as M. Tuberculosis from one person to another”
TB
Transmission
- There are several type of Mycobacteria that cause TB
- M. tuberculosis is the most common
- Some others: M. bovis, M. africanum, M. microti, M. canetti
***M. avium complex DOES NOT caused TB
TB
Transmission
-
Air Droplet Nuclei - spread person-to-person
- The other person inhales the nuclei and BAM!
- Can catch it from:
- Coughing
- Sneezing
- Speaking
- Singing…
TB
Transmission
Probability of Transmission
- Chance of Transmission depends on:
- Infectiousness of person w/ TB dz
- Enviroment in which exposure occured
- Blewett 15… no good.
- Length of Exposure
- Virulence (strength) of tubercle bacilli
TB
How to stop transmission!
- Isolate the infected person(s)
- Negative pressure room in hosp.
- Provide effective treatment to infectious persons ASAP
TB
High Risk Groups
@ High Risk for Becoming Infected
- Close contacts
- Foreign born
- Low-income & homeless
- Healthcare workers serving high-risk groups
- Racial and ethnic minorities
- Infants, children, & adolescents
- Injectable drug users
TB
High Risk Groups
People at High Risk for developing TB Dz after Infection!!!
- People living with HIV
- W/ medical condition that increases the risk
- Those infected w/ M. tuberculosis w/in past 2 years
- Ages 4+ younger
- Injectable drug users
TB
High Risk Groups
People Living with HIV
- HIV is the Strongest known risk factor for developing the disease
- TB is the Leading Cause of Death for those w/ HIV/AIDs
TB
High Risk Groups
People with Certain Medical Conditions
- Prolonged therapy w/ corticosteroids & other immunosuppresive therapy
- ex: TNF-a antagonists
- Silicosis
- Diabetes
TB
High Risk Groups
Recently Infected
- If you are infected w/in past 2 years, more likely to develop disease!!
- 5% risk of developing disease in the first two years
- 10% risk over a lifetime
- (unless you get treated)
TB
High Risk Groups
Ages under 4 Years
- Undeveloped Immune System =’s Higher Risk!
TB
Pathogenesis: Latent TB Infection
“How an Infection or Disease develops in the Body”
- Latent TB Infection (LBTI)
- Tubercle bacilli in are in body, but
- Immune System is keeping them under control!
*NOT INFECTIOUS!!!
- Dectected by:
- Mantoux TB Skin Test (TST)
- Blood tests: Interferon-gamma release assays (IGRAs); ex: T-SPOT
TB
Pathogenesis
TB Disease
- Immune System CANNOT keep tubercle bacilli under control
- May develop soon after infection, or man y years later
- About 10% w/ LTBI will develop TB
- May develop soon after infection, or man y years later
If you have the Disease, you are often Infectious!!
TB
Pathogenesis, pt. 1
- Droplet Nuclei containg the Tubercle Bacilli are inhaled
* Enter the lungs &
* Travel to the small air sacs (alveoli)
* These nuclei just sneak through your system!
- Droplet Nuclei containg the Tubercle Bacilli are inhaled
- They mutiply in your alveoli (asymptomatic)
* Infection begins…
- They mutiply in your alveoli (asymptomatic)
- Small number of Bacilli enter bloodstream & spread through the body!
- See next flashcard
TB
Pathogenesis, pt. 2
- In 2-8wks, immune system produces Macrophages that surround tubercle bacilli & keep it in check!
* Macrophages form a barrier shell keeping the bacilli contained (LTBI)
- In 2-8wks, immune system produces Macrophages that surround tubercle bacilli & keep it in check!
- 5.
TB
LTBI vs. Disease
- Latent:
- Inactive/contained
- TST or blood test
- Normal CXR
- No Symptoms, not infectious, not a Case!
- Disease:
- Active/bacilli are multiplying in body
- TST or blood test
- Abnormal CXR
- Symptoms: cough, fever, weight loss
- Infectious b4 treatment
- THIS IS A CASE OF TB!
TB
Diagnosis
- Mantoux tuberculin skin test (TST)
- Tuberculin injection
- Tuberculin = proteins from inactive bacilli
- test = reaction at injection site
- Induration (swelling), measure swelling in mm.
- 15mm = + in healthy person
- test = reaction at injection site
- Tuberculin injection
- Blood-tests: Interferon-gamma release assays (IGRAs)
- Measures immune reactivity
- Pros:
- Single patient visit, fast results
- More accurate results than skin test
- Cons:
- Process blood samples quickly
- Limited data in use 4 some pops
- Errors can occur in running/interpreting tests
TB
Treatment
LTBI
- LTBI treated to prevent development into disease
- Treated with medication
- ex: Isoniazid for ~9months
TB
Pathogenesis
Progression from LTBI to TB Disease
- Highest risk first 2 years after infection
- Detect early!
- Prevents new cases
- Conditions = increasing probability
- HIV infection
- Organ Transplant
- CXR suggestive of previous TB
- DM
- Silicosis
TB
Diagnosis
Medical Evaluation
Components include:
- Medical Hx
- PE
- TB Test
- CXR
- Bacteriological Exam
TB
Diagnosis
Medical Hx:
Does patient have…
- Disease sxs
- Been exposed
- Any risk factors
- LTBI or TB dz before?
TB
Lungs
TB
General Symptoms
- Fever
- Chills
- Night Sweats
- Weight Loss
- Appetite Loss
- Fatigue
- Malaise
*Cough lasting 3+ weeks
**Chest pain
** Sputum or blood coming up wit cough
TB
Chest X-Ray
Inflitrates & Cavities
- CXR may show:
-
Inflitrates
- Collections of fluid & cells in lung tissue
-
Cavities
- Hollow Spaces w/in lung
-
Inflitrates
TB
Bacteriologic Examination
Pulmonary TB
- Sputum Sample Specimen Collection:
- Patient cough into sterile container
- 3 sputum samples for examination
- Collect in 8-24 hour intervals
- One early in the morning!
- Induced Sputum Collection = use when patient cannot cough up sputum on their own. Label “induced specimen”
- Bronchoscopy: Use if the 2 above fail
- Gastric Washing: Use is all above fail. Used more often in children
TB
Bacteriologic Examination
Extrapulmonary TB
- Can collect samples other than Sputum depending on affected body part
- Ex: Urine samples for TB of kidneys
- Fluid samples from around Spine
TB
Bacteriologic Examination:
Examination of AFB Smears
- Specimens smear onto glass slide
-
AFB = mycobacteria that remain stained after being washed in acid solution
- “Red Snappers”
TB
Bacteriologic Examination
- Nucleic Acid Amplification Tests (NAA)*
- &*
- Culturing*
- Directly ID M. tuberculosis from sputum specimens by:
- Amplification of DNA & RNA segments
- Can guide clinical decisions
- Does not replace the AFB smear
- Culture all specimens!! IDs TB
TB
Bacteriologic Examination
Drug Susceptibility Testing
- Conducted when patient is first found to have positive TB culture
- Determines which drugs kill the TB Bacilli
- Resistance vs. Susceptibility!!!
- Resistance = drugs can no longer kill bacteria
TB
Drug-Resistant TB
Primary & Secondary
- Primary:
- Caused by person-to-person transmission of drug resistant organism
- Secondary:
- Develops during treatment
- Bad practices:
- Inappropriate regimen
- Incompliance
- Bad practices:
- Develops during treatment
TB
Drug Resistant TB
- Mono-resistant: Resistant to any one TB Treatment
- Poly-resistant: Resistant to any 2 TB drugs
- (not Isoniazid & Rifampin together)
- Multidrug Resistant: Resistant to Isoniazid & Rifampin
- Extensively Drug Resistant: Resistant to so many drugs!!
TB
Sites of TB Disease
- Common sites:
- LUNG
- Brain
- Lymph nodes
- Pleura
- Spine
- Larynx
- Bone
- Kidney
*Extrapulmonary locations are found more often in HIV-infected, immunocompromised
TB
Treatment of TB Disease
- TB disease must be treated for at least 6 months, sometimes longer
- Initial Phase - 4 drugs used:
- First 8 weeks
- More bacilli killed during this phase
- Continuation Phase - at least 2 drugs used
- Relapse:
- Occurs when treatment is not continued for long enough
- Surviving bacilli may cause TB at a later time
TB
Treatment
Drugs
Inital regimen should include these 4 drugs:
- Isoniazid
- Rifampin
- Pyrazinamide
- Ethambutol
(At least 2 of these drugs should be susceptible to dz; using only 1 drug can create a population that is resistant to drugs)
*TB is a treatable, curable disease!
**Work with patients to adhere to treatment regimen
