Infectious Disease #3 Flashcards
How do you check for Helminth infections?
Stool sample - Ova & Parasites (O&P)
Indications to run a O&P checking for Helminth?
Unrelenting diarrhea
Fever
Abdominal bloating
Blood in the stool
Ascaris (hookworm)
Cestoda (tapeworm)
Enterobius (pinworm)
Ascaris is?
bookworm
Cestoda is?
tapeworm
Enterobius is?
pinworm
Interfering factors with stool sample from worms?
- Urine may inhibit growth
- recent barium studies (obscures parasites) - barium swallow or barium enema
- Drugs: Abs, bismuth ( pepto)- black tarry stool? make sure they are not taking pepto), mineral oil
Procedure for stool sample collection?
Explain procedure to patient:
No urine or TP into bedpan or container
Instruct pt to defecate into clean container
Place small amount of stool into sterile collection cup
Rectal swab could also be used - it patient is unable or unwilling to give sample
Post-procedure stool collection?
Use gloves and proper contact precautions when handling.
Send specimen promptly - so nothing dies off
Stool sample collection results: labs?
Inform about which ova or parasite they found in the stool
Enterobius organism?
Enterobius vermicularis
*pin worm - who gets it? children - sucking there thumb after scratching their tush**
Tape test is for what worm?
pin worm
Procedure for tape test?
Place a strip of clear tape in the perianal area
Remove it in the am before rising
Press directly to the glass slide for examination
*put the tape on at night cause the female worms come out and lay eggs outside the rectum, you can do bx of colon and O&P for pin worm but this test is best **
Schistosomiasis AKA?
“Bilharzia” or “Snail Fever”
Schistosomiasis gold standard?
O&P
What other tests can you do for Schistosomiasis that is not a GS?
Bx of rectum, colon, liver, bladder
Antigen tests in development (not in US)
ELISA
Schistosomiasis ELISA?
Schistosomal Ab
Requires eggs to mature to adults (6-8 wks) - because we need adult worms, we cant find the eggs
*big liver cysts full of worms
, vague abd pain and they get distended and bloated **
eating what food can give you Trichinosis?
pork
What will a CBC show if there is a Trichinosis infection?
eosinophilia ( all worm infections really)
Trichinosis test?
Trichinella-specific Ab titer
What is the Trichinella-specific Ab titer and how long after infection is it detectable?
IgG (+) 12-60 days after infection
What test gives a definitive diagnosis and is infrequently performed for Trichinosis infection?
Biopsy of muscle
*no bx of muscle first line**
What Trichinosis test allows typing of trichinella species?
Biopsy of muscle
- typing of the trichinella ? then yes the answer is bx of muscle**
How does Amebiasis infection happen?
fecal to water and then little kids drinking out of hoses
Two type of Entamoeba, which causes the issue and makes patients symptomatic?
Entamoeba histolytica
Gs for Amebiasis?
Stool for O&P
Other tests for Amebiasis that is not GS?
IgG Ab tests - unreliable
Incubation period for Malaria?
7-30 days
When do Malaria symptom attacks occur?
Attacks occur every second or third day
Symptoms of Malaria classic attack?
Lasts 6-10 hours
Cold
Hot
Sweats
Clinical Dx of Malaria?
Travel within the last 12 months Fever Chills Sweats Pattern of malaria
Labs for Malaria test for?
Anemia ( hemolytic anemia )
Renal failure
Hypoglycemia
Hyperbilirubinemia ( hemolysis)
Acid-base disturbances ( without renal failure)
Malaria GS test?
Blood smear:
- Use giemsa stain
- Microscopic direct exam
* you can actually see parasite in RBC**
What stain does the blood smear for malaria use?
giemsa stain
Test for antigen detection for Malaria?
Serum study - quick , like preg. test
Rapid Diagnostic Test - used more in the field , can use serum
Accuracy needs improvement
Cannot tell severity of disease
Malaria antigen test disadvantage?
Cannot tell severity of disease
PCR for Malaria, is it a serum or antigen study?
serum
What malaria test is most useful in defining species of malarial parasite after dx of infection is made?
PCR
What Malaria test uses parasite nucleic acids ?
PCR
What Malaria tests measures past exposure?
ELISA
IFA
*good a measuring past exposure not acute exposure; past exposure might give you some immunity **
Toxoplasmosis organism?
Toxoplasma gondii
Toxoplasma gondii causes severe __________ symptoms and is part of the _____ diseases.
congenital
TORCH
- Can cause severe sxs in immunocompromised patients**
Indication to test for Toxoplasmosis?
r/o congenital infection in infants
Pregnant women (baseline)
HIV + patients (baseline)
Acute infection
Toxoplasmosis GS?
IFA (indirect fluorescent antibody test)
For the GS test for Toxoplasmosis IgM rises in about _ week and peaks - months.
rises about 1 week
peaks about 2-3 months
For the GS test for Toxoplasmosis IgG rises in about _ week and peaks - months.
rises in 2 weeks
peaks about 2-3 months
*can be positive for 5 years**
Issues with Toxoplasmosis testing?
Difficulty isolating in culture
False Positives
What conditions can cause a false positive in a Toxoplasmosis infection?
Rheumatoid arthritis , LUPUS
Other autoimmune disease
Indication for testing wound culture?
Signs of infection
Post-op pt with FUO (culture from incision?)
Spontaneous drainage from a wound
Would culture: test should be done ______ abs tx.
before
Wound Culture: what is started after the culture and sample collected?
Empiric abx
Wound Culture: Preliminary results in about __ hours? Giving us what information about the infectious organism?
24
giving us gram stain and shape and configuration
gram - = pink
gram + = purple
Wound Culture: Final report within __-__ hours
48-72 hours
Based on the cell composition
gram-positive bugs have large peptidoglycan layer and thus are more ______ in color?
Blue
Based on the cell composition
gram-negative bugs have smaller peptidoglycan layer and an outer membrane and thus are more ____ in color?
Red
Culture and Sensitivity final report?
susceptible versus resistant
The Abx sensitivities reported are MICs (minimal inhibitory conc.) The numerical portion of the MIC is specific for that Abx and does not represent a relationship between the potential efficacy of one Abx over another.
*the number do not matter to us, but what does matter is the greater than or less than signs**
S <= (any number) means?
effective at lowest dilution tested
*it is sensitive to less than or equal to = best
Example: Ampicillin S <= 0.25. Interpretation:
This organism is susceptible to Ampicillin at the lowest dilution tested.
**
R >= (any number) means?
Unlikely to be effective
- R >= ..”it is the worst, not killing any bacteria at all**
What is a product of cell metabolism?
Lactic acid
What can cause lactic acidosis?
Circulatory insufficiency
Shock
Severe infxn
Bowel ischemia
Cardiac failure
seizures
Lactic acid can be tested from what sample?
serum or CSF
Indications to test lactic acid?
r/o lactic acidosis
Indicator of sepsis/septic shock
*good indicator of sepsis to septic shock : mesenteric / bowel ischemia **
Normal values of lactic acid from venous blood?
5-20 mg/dL
0.6-2.2 mmol/L
Normal values of lactic acid from arterial blood?
3-7 mg/dL
0.3-0.8 mmol/L
What are some interfering factors of Lactic Acid?
Drugs (ASA, cyanide, ethanol)
Prolonged intense exercise
Clenching fists tightly for prolonged period with blood draw
Lactic acid critical value?
> 4mmol/L
When will lactic acid be elevated?
Shock
Sepsis
Tissue ischemia
CO poisoning ( hypoxia)
Uncontrolled DM - where the cells are starving
What signifies necrotizing skin or deeper tissue infection?
soft tissue gas
- Can be related to variable pathogens, Can also be seen in penetrating trauma**
- Can be seen because of gas created by bacterial respiration ; by-product of bacteria in the skin**
