Doc, its Ebola Flashcards
Rapid Strep Test
Swab, ELISA technique to detect Group A strep cell wall
Specificity >95%
Sensitivity > 90%
Good technique improves sensitivity
Throat pathogens
Streptococci, Gonococci, Meningitides, pertussis, diptherium
Throat culture
culture on chocolate agar or strep-specific agar, gram stain and culture is ID’d
usually takes 2 days
Negative rapid strep, negative throat culture
if sx persist 3+ weeks, could be acid reflux, or throat cancer. Could also be a fungus- candida albicans, thrush in immunocompromised pts
Streptolysis O
Produced by strep pyogens. Its toxic to PMNs, RBCs, platelets, etc. It increases the virulence of strep-pyogens.
ASO titer
used to detect recent infection with a group A strep. Rise over several weeks, are highest 3 weeks post infection. Draw an ASO titer when a patient has possible systemic manifestations of a sequelae of group A strep (has rheumatic fever, rash, glomerulonephritis)
Mononucleosis
Epsein Barr virus, over 80% of US pop has been exposed. Similar sx to strep throat
Rapid Mono
Detects IgM of EBV, usually present by day 6 85% sensitivity, 100% specificity Blood test
EBV titer
Do when a rapid mono is not available, if you suspect mono but rapid is negative, or to detect the timing of the infection
The most common congenital infection
CMV Cytomegalovirus
CMV
TORCH Virus Causes mono-like sx. 60 day incubation period!
CMV tests
- ELISA test 2. Latex-agglutination test you are evaluating the presence of CMV antibodies. Can reactivate after years.
The Flu
Fever greater than 100 and Myalgias are key! Caused by strain A or B
Rapid Flu test
More than 10 exist. Sometimes strain specific, and rapid do not identify the subtype/exact strain. (type A2). Will do a rapid flu if sx started within 48-72 hrs. contraindicated if outside this window- no treatment and the test itself is not comfortable.
Rapid flu disadvantages
only 50-70% sensitivity (higher in children than adults because children shed the virus longer). high rate of false negatives. nasopharyngeal swab
Flu Viral culture
The gold standard for flu diagnosis. Identifies which strain of flu. Takes 3-10 days.
Flu PCR
High sensitivity, differentiates between sub-types. more costly and time consuming. Only do in the seriously ill and to track flu outbreaks.
Sputum cultures
Lung sputum samples (expectorated from patient) can be collected and cultured in lab. gram staining can tell if bacteria, viral or fungal. Fungal can take 6-8 weeks to analyze! This is usually done for bacterial cultures.
Pertussis
whooping cough. Bacterial URI caused by bordetella pertussis. Also have an inspiratory whoop, coughing fits and post cough emesis
Pertussis test
It is another nasopharyngeal test. DO NOT use cotton or rayon swabs! only us Dacron swab with flexible shaft for sample collection.
Bordetella pertussis PCR
High cost Not affected by previous abx use 1-2 days for results
Bordetella pertussis Culture
GOLD STANDARD 30-60% sensitive, but 100% specific. Can take 7-10 days.
RSV
Respiratory Syncitital Virus Common in children: URI, fever, cough, apnea. Can lead to hospitalizations and even death
RSV testing
Nasal secretions analyzed via rapid antigen test (30 minutes, 90% specificity and sensitivity), Culture (4-14 days, too long) or PCR (can assay 33 pathogens in one test!)
Tuberculosis
spread through the air Cough, fever, weight loss, night sweats, fatigue, skeletal, GI and GU
TB skin test
also known as: Tuberculosis skin test, Purified protein derivative, Mantoux test, Tuberculin test, Tubersol
TB test, how it works
Inactivated TB culture is injected subdermally. The inactive culture contains mycobacterial PPD antigens, which causes a delayed hypersensitivity reaction by the T lymphocytes in its who have been exposed to TB whether it is active or dormant
TB test procedure
0.1mL TB PPD injected. 48-72 hrs later the skin is read. Test cannot determine if infection is active or dormant. Results will be positive 6-8 weeks after TB infection. TB will be positive for life- don’t test a known positive. Read from bump edges, not red edges.
TB Negative
less than 5 mm
TB > 5mm
TB positive in HIV, close contact with +, immunocompromised, CXR of old TB
TB>10mm
Positive in children under 4, foreigners of high risk country, IV drug users, people who work in high risk setting, economically disadvantaged, Cancer, diabetes, dialysis
TB>15
Positive in healthy, low risk, over the age of 4
Things that will result in a false negative TB
infection less than 8 weeks ago, immunosuppressed pt, or someone with waning natural immunity, MMR vaccine in past 4-6 weeks.
Things that will result in a false positive TB
Infection with non-TB mycobacterium or a BCG vaccination
IGRA test
TB test to use if you suspect a latent TB infection. Can be used regardless of BCG vaccination status. More specific. Cannot differentiate between latent and active, but can be used for latent. More expensive than normal TB. QFT-GIT and T-spot are the two available tests. Blood draw. Still uses an ELISA technique.
When to use IGRA test
if your patient comes from a country that administers BCG vaccines if your patient is not compliant in their TB reads.
H. pylori serologic test
least expensive, most commonly used. results in 2-3 days. Least sensitive. tests IgG, positive 2 months post infection.
H.pyelori bacterial culture
gastric mucus specimen is cultures on enriched medium. Takes at least 5-7 days.
H pyelori rapid urease test
biopsied gastric mucosa + urea on pH indicator. results in 3 hours, but can only be done on pts undergoing endoscopy.
H. pyelori stool specimen
ELISA technique, using fresh stool. very accurate. Usually used to test if H.pyelori has been eradicated.
H. pyelori urea breath test
orally administer radioactive carbon urea. positive result will have radioactive CO2 exhaled. Expensive, but generally non-invasive and reliable.
H. pyelori produces
increased urease
Pathogenic poop
Salmonella
Shigella
Yersinia
Campylobacter
E. coli pathogenic
C.diff
Staphylococcus pathogenic
SSYC
Normal in your poop
Enterococcus
Bacteroides
Proteus
Pseudomonas
Escherichia coli
Clostridium
Staphylococcus aureus
Candida albicans
stool culture staining
not gram stain
stain with methylene blue
can sometimes see leukocytes- shigella and salmonella
standard stool culture
salmonella
shigella
campylobacter
(may need to request yersinia and enterohemorrhagic e. coli)
C. diff testing
ordered separately from standard stool culture!
can only be performed on loose/watery stools.
Tests for toxins A and B
C diff PCR
Result in 1 hour, good Specificity and sensitivity.
c diff EIA test
75% sensitivity, 99% specificity
Can have false negative and you need more toxin to be present to detect.
c. diff cell culture assay
GOLD STANDARD for c.diff toxin diagnosis
Can take 2 days and is labor intensive
OVA and parasites in stool- who to check?
recent travel
daycare workers
AIDS pts
community outbreaks
parasites commonly found in stool
hookwork
tapeworm
giardia
cryptosporidium in AIDS pts
Hemoccult test
aka fecal occult blood test (FOBT) or stool guaiac
checks for occult bleeding from GI or to evaluate colorectal cancer, IBD, and hemorrhoids
False positives with red foods
False negatives with Vitamin C
Low sensitivity and low specificity
Normal blood in GI tract
2-2.5 mL daily
these tests detect 5mL, so if it is positive (blue stain) there could potentially be abnormal bleeding. usually do over a 3 day span.
