CS2 Exam 2: Infectious Disease/Fecal/GU Testing

What is tuberculosis?

bacterial infection of the lungs

What is the agent of tuberculosis?

Mycobacterium tuberculosis

What is the gram and shape of tuberculosis?

- G +

- rod

- aerobe

How is tuberculosis spread?

airborne droplets

How is tuberculosis stained?

acid-fast bacillus staining

What are the 2 stages of tuberculosis?

1. primary (active and latent)

2. secondary (reactivation)

What primary active TB?

- bacteria not contained by macrophages

- bacteria replicates

- symptomatic contagious

What is primary latent TB?

- bacteria contained by macrophages

- bacteria do not replicate

- non-contagious

What is secondary TB?

Immunity wanes --> contained TB in macrophages deteriorates --> Bacteria begin to replicate --> symptomatic contagious

What is extrapulmonary tuberculosis?

- infection outside the lungs

- active infection goes untreated or hematogenous spread

What is miliary tuberculosis?

the development of active tubercles throughout the body

What are 2 screening options for tuberculosis?

- PPD

- Quantiferon Gold /T-spot

What is 1 diagnostic option for tuberculosis?

AFB culture

What are the 4 screening AND diagnostic options for tuberculosis?

- PCR/NAAT

- CXR

- AFB smear

- IgG antibodies

What is the QuantiFERON TB GOLD test?

- blood measurement of cell-mediated immune reactivity of M. tuberculosis

- preferred testing over PPD in ages OVER 5 years old

- whole blood specimen

What are the advantages of the QuantiFERON TB GOLD test?

- can be performed on patients with prior Bacille Calmette-Guerin vaccination

- no reader bias/error

- 1 visit

-no cross rxn with other mycobacterium species

- 24 hour results

What are the disadvantages of the QuantiFERON TB GOLD test?

- cannot differentiate active from latent disease

- higher cost

- false - are possible

What is a PPD test?

a purified protein derivative of tuberculin was injected intradermally, and if a patient has active or latent disease, it would cause a localized inflammatory reaction (can take 6 weeks to become positive after infection)

What is a PPD test known as?

- tuberculin skin test

- Mantoux text

- tine test

Explain how to administer a PPD test?

- 0.1 mL PPD solution injected to form a 1 cm wheal

- do not bandage

- come back in 48-72 hours

- measure diameter of the INDURATION ONLY

What should only be measured with the PPD test?

induration (the raised surface not the redness)

What are advantages of PPD test?

inexpensive

What are the disadvantages of the PPD test?

- cannot diff active from latent

- reader error is possible

- repeat testing is needed

- cross reaction with other mycobacterium species

- cannot be given with the BCG vaccine

What are the contraindications of the PPD test?

- previous severe reaction to TST

- patient with documented TB

- patient who received BCG vaccine

What are the ways of getting a false (-) on the PPD test?

- subcutanously instead of intradermally

- immunocompromised patient

- improper storage/dosage of PPD

- waning rxn

In what patients is 5mm induration considered (+)?

- HIV (+)

- close contacts with TB

- CXR consistent with healed TB granulomas

- organ transplant recipient/immunosuppressed

In what patients is 10mm induration considered (+)?

- immigrants within the past 5 years

- IV drug users

- nursing home/prison resident

- medical personelle

- high-risk populations

In what patients is 15mm induration considered (+)?

all other populations

What is seen on a CXR with tuberculosis?

- ceaseating granulomas

- apical caviations

- ranke complex

What is the difference between a Ghon Lesion and Ghon Complex?

- lesion = granuloma alone

- complex = granuloma + enlarged hilar lymph nodes

What is an AFB smear?

- acid fast bacillus stain

- a way of identifying TB since it needs a special culturing medium

What is the main collection for AFB smear?

- sputum culture (deep cough from lungs after waking)

- get at least 3 specimens

AFB smear has a 50% false ___ rate.

(-)

1 multiple choice option

Can AFB smear be used to diagnose tuberculosis?

- no

- start empiric therapy

- monitor treatment efficacy

1 multiple choice option

What is the gold standard diagnostic test for tuberculosis?

culture

How long does a tuberculosis culture take?

4-6 weeks

What is the collection of a tuberculosis culture?

sputum culture (deep cough x 3)

What are 2 techniques to evaluate tuberculosis culture?

- BACTEC

- PCR/NAAT

What is BACTEC, and how long does it take?

- method of culture that quantifies the amount of CO2 produced by a bacteria

- takes 1 week

- differentiates M. tuberculosis from other mycobacteria types

What is PCR/NAAT, and how long does it take?

- method of culture that identifies mycobacterium DNA

- takes 24-48 hours for pulmonary specimens

What tests will be (+) for LATENT TB infection?

- PPD

- QuantiFERON

What tests will be (-) for LATENT TB infection?

- culture

- smear

- PCR/NAAT

What tests will be (+) for ACTIVE TB infection?

- PPD

- QuantiFERON

- culture

- smear

- PCR/NAAT

Where do atypical mycobacterium usually reside?

soil and water

What are 5 diagnostics for atypical mycobacterium?

- CXR

- AFB smear

- AFB culture (high rate false -)

- PCR/NAAT of tissue (confirmatory)

- biopsy

What is hepatitis?

inflammation of the liver that can lead to liver cell death via necrosis and triggering of apoptosis

What 6 tests reflect liver function?

- Aspartate aminotransferase (AST)

- Alanine aminotransferase (ALT)

- Albumin

- Alk Phosphatase

- Prothrombin Time

- Bilirubin

What does an AST: ALT ratio < 1 indicate?

viral hepatitis

What are the types of viral hepatitis?

- HAV

- HBV

- HCV

- HDV

- HEV

- Epstein Barr Virus

- Cytomegalovirus

What is acute viral hepatitis?

- hepatocellular injury lasting < 6 months

- Viral agent attacks hepatocyte

- Incubation period

- Inflammation

- Changes in liver function studies

- Signs and symptoms appear

What is chronic viral hepatitis?

- > 6 months of hepatocellular injury

- immune-mediated attack of the liver secondary to persistent viral hepatitis

What kinds of viral hepatitis have the potential to become chronic?

- Hepatitis B

- Hepatitis C

- Hepatitis D

- Hepatitis E

What are the 3 diagnostics for Hep A?

1. HAV-IgM ab

2. HAV-IgG ab

3. HAV RNA

What diagnostic test for hepatitis A is first to rise, peaks 1 month after exposure, and appears 5-10 days before clinical symptoms?

HAV-IgM antibody

What diagnostic test for hepatitis A signifies lifelong immunity or vaccination?

HAV-IgG antibody

What diagnostic test measures the hepatitis A viral load in patients with suspected acute infection but it's too soon for IgM to be detected?

Hepatitis A Virus RNA

What IgM/IgG indicates an acute Hep A infection?

- IgM positive

- IgG +/-

What IgM/IgG indicates a previous Hep A infection or vaccination?

- IgM negative

- IgG positive

What is the anatomy of the Hep B virus?

- DNA virus

- outer capsule = surface antigen

- inner core = core antigen and envelope antigen

What are the diagnostics for Hep B?

1. HBsAg & HBsAb

2. HBcAg & HBcAb

3. HBeAg & HbeAb

4. HBV DNA

What hepatitis B diagnostic is the first to increase?

Hepatitis B surface antigen (HBsAg)

What diagnostic indicates an active HepB infection?

Hepatitis B surface antigen (HBsAg)

What diagnostic indicates resolved infection, natural immunity, and vaccination immunity for HepB?

Hepatitis B surface antibody (HBsAb)

What are the two types of hepatitis B core antibody (HBcAb)?

- IgM HBcAb

- total HBcAb

What diagnostic indicates acute infection of HepB?

IgM HBcAb

What diagnostic indicates previous infection of HepB?

total HBcAb

What diagnostic indicates early and active disease as well as predicts the development of chronic hepatitis of HepB?

Hepatitis B envelop antigen (HBeAg)

What diagnostic indicates the end of the acute infection phase of HepB?

Hepatitis B envelop antibody (HBeAb)

What diagnostic is a direct measurement of HBV viral load for HepB?

HepB DNA

What is hepatitis B DNA test helpful in terms of treatment?

Determining candidacy for antiviral therapy & disease monitoring

What are the 2 diagnostics for Hep C?

1. anti-HCV ab

2. HCV RNA

What is the initial screening for hepatitis C?

Anti-HCV antibody

What diagnostic indicates HCV recombinant core antigen for HepC?

Anti-HCV antibody

What diagnostic indicates viral load for HepC as well as monitors response to therapy?

HCV RNA

What are the 2 diagnostics for HepD?

1. HDV RNA

2. Anti-HDV Antibody

What does HepD require for infection?

HepB

Are there any HepE diagnostics available?

- tests not commercially available in the US

- Anti-HEV IgM & IgG

- HEV RNA

What is autoimmune hepatitis?

chronic, inflammatory disease of the liver characterized by circulating autoantibodies and elevated serum globulin levels

What does the diagnostics of autoimmune hepatitis look like?

- Elevated AST/ALT (10-20X the normal limit)

- Elevated of gamma globulins: IgG

- Presence of autoantibodies

What are the autoantibodies present in autoimmune hepatits?

- Antinuclear antibody (ANA)

- anti-smooth muscle antibody (ASMA)

- antimitochondrial antibody (AMA)

- atypical perinuclear antineutrophil cytoplasmic antibody (p-ANCA)

- anti soluble liver antigen (anti-SLA)

- anti-double-stranded DNA antibody (anti-dsDNA)

What are the screening recommendations for HIV?

- adolescents 13-64

- adults with risk factors

- pregnant women

- newborns with HIV + mom or mom with unknown status

What are the screening options for HIV?

1. p24 antigen

2. HIV-1/HIV-2 Antibodies

3. combined p24 + HIV-1/HIV-2 Antibodies

What is a confirmation test for HIV?

NAAT

What is the p24 antigen?

an HIV protein that is elevated within as early as 2-6 weeks after a person becomes infected

What's the technology utilized for a p24 antigen?

ELISA like assay that

detects protein p24

When does p24 antigen rise?

- 2-6 weeks post-infection

- can detect HIV infection before antibody seroconversion

When is the p24 antigen used?

- evaluate the antiviral activity of anti-HIV treatment

- support active neonatal HIV infection

- screen donated blood

What are the two strains of HIV?

HIV-1 and HIV-2

What are the methods of HIV collection?

1. traditional blood draw

2. point of service rapid antibody screening

3. oral mucosa transudate

4. urine antibody test

What is the collection of rapid POC antibody test for HIV?

finger prick or saliva

What do you need in addition to a rapid POC antibody test for HIV confirmation?

NAAT

What is the collection of oral mucosal transudate antibody tests for HIV?

- oral mucosa

- the saliva will contain the antibodies for the virus, not the virus itself

Why is there always one line visible with oral mucosal transudate antibody test for HIV?

- control line

- (+) result will have 2 lines

What is collection for urine sample antibody test for HIV?

- urine specimen

- detects HIV antibodies

Which mode of antibody collection for HIV is best?

serum

What is the confirmatory tests for HIV?

NAAT test

What is the MOA of NAAT test for HIV?

quantifies HIV RNA viral load

What is the clinical use of the NAAT test for HIV?

- differentiates true newborn HIV infection from passive antibodies

- confirms a true HIV infection

What are false positives for HIV serology?

- Technical errors

- Assay with reduced specificity

- HIV-1 trial vaccine

- Hypergammaglobulinemia

What are false negatives for HIV serology?

- Technical errors

- Early incubation stage

- Delayed seroconversion

- Immunosuppression