Infectious diseases B7 Flashcards
1/4 of patients with AIDS will develop what?
CMB retinitis
What is #1 infectious disease related cause of blindness?
Trachoma! (important)
caused by chlamidya trachomatis (sp?)
Chlamidya trachomatis A B and C
Presence of microbe on or in the body
Colonization
Is infection required for bacterial-related disease?
NO
True/False: A virus that infects your eye may have trouble infecting other parts of your body
True
Non living infectious particles
Viruses
Pathogen present in diseased animal
Pathogen isolated and grown in culture
INoculation of healthy animal with isolated pathogen causes disease
Koch’s postulates
What are some exceptions to Koch’s postulates?
we tend not to do this to people (we recover pathogen, or see evidence that a person is infected)
- difficulty isolating the virus
- ethical probs
True/False: An STD can affect the eye.
True
True/False: The inner part of the eye is sterile.
True
What are some sterile body sites?
Blood CSF Pleural fluid Tissues Lower respiratory tract Bladder Inner part of eye
What are some non-sterile body sites?
Eye/Mouth/Nose/Upper respiratory
Skin
Gastrointestinal tract (GI)
Urethra
If we find coagulase negative staphloccocus in a patient what do we consider?
assumed it is a contaminant until we have proved that it is a pathogen
Have a healthy dose of doubt about the gram stain you are sent. (FYI)
Use it as a clue but don’t take it to the bank. After the culture is old it gets hard to read
Wet preparations include what?
KOH dissolves protein tissue, doesn’t work on fungal wall.
Calcoflour white: fungi turns it fluorescent
Most common lab diagnostic stain used for bacteria?
Gram stain
Acid fast stain is for TB, what names are there for it
Ziehl-Neelsen or (Kinyoun)
Blood smear for white blood cell, epithelial inclusion bodies, protozoans. Can stain icanthomoeaba…
Wright-Giemsa stain can stain it in your eye
Potassium hydroxide (KOH)
10% KOH Dissolves keratin but DOES NOT DISSOLVE FUNGI CELL WALL (IMPORTANT)
Calcoflour white (CWF)
10% KOH and CWF dissolves tissue (KOH) and binds to chitin in fungal wall (fungi appear bright white)
Gram stain process
Put sample on slide
Heat fixed to seal organisms on the slide
Flood slide with crystal violet stain
Iodine- (yellos, mordant, seals bacterial cell wall, seals thick walls well, but doesn’t seal thin walls)
Between every stage wash with water
Then use alcohol for decolorization
Then use safranin to Counter stain
Gram stain which colors are positive and negative?
Purple= Gram positive Red= Gram negative
Thick peptidoglycan is what kind of grain stain?
Gram positive (purple/blue)
Thin peptidoglycan is what kind of grain stain?
Gram negative (Red)
ETOH can wash away crystal violet safranin counterstains in _______________.
thin peptidoglycan
Spheres are called what?
Rods are called what?
COCCI
BACILLI
All cocci are what?
Gram positive!! (except Neisseria and Morazxella, both can be in eye)
Vast majority of pathogens are what?
gram-negative rods
If you are debating whether a bacteria microbe is cocci or bacillus and it is small what is it likely?
likely a bacillus because Cocci are big
Pair of spheres
Diplococcus
Chains of spheres
Streptococcus
Clusters of spheres
Staphylococcus
All gram positive rods are ____.
big
True/False: Gram positive rods can be coccobaccili.
True
Spiral has 3 forms what are they?
Vibrio: coma shapped
Spirochetes: thin walled helical, w/o flagella
Syphillis is a spiral rod, won’t see it on gram stain… (CANNOT SEE SYPHYLIS ON GRAM STAIN) Treponema pallidum
If you test negative for disease, and you dilute it out and repeat it and its positive, it could be what?
Prozone
Gram stain red means what?
Acid fast stain red means what?
Gram stain= positive Acid fast= negative (use acid alcohol to have a very rough acid to strip out and damage cell wall except for acid fast cells) Use carbolfuschin Used on mycobacterium tuberculosis
Gram stain red means what?
Acid fast stain red means what?
Gram stain= negative Acid fast= positive (use acid alcohol to have a very rough acid to strip out and damage cell wall except for acid fast cells, because of lipid) Use carbolfuschin Used on mycobacterium tuberculosis
Chlamydia producess intracellular pockets called ______________.
inclusion bodies (FRIED EGG LOOK)
KNOW IF Chlamydia positive or chlamydia negative from stains.
-Chlamydia are obligate and intracellular
-Seen with wright giemsa stain and also seen with iodine stain
A person who has shingles has to have had what?
chicken pox
Vericella zoster follows dermatome
-bad things happen if get into eye
What is a problem with cultures?
Positive cultures generally more meaningful than negative cultures
-Neg may be false neg, positive may be contaminant
What are two unculturable bacteria?
chlamydia, syphilis
How is chlamydia virus like? (important)
Intracellular (can see it with inclusion bodies)
If coagulase negative staph what is it probably?
Probably contaminant (know it)
What agar supports a broad range of bacteria?
What agar contains extra growth nutrients?
What agar contains substances that prevent growth of some but not others
What agar gives visual clues to identification?
General
Enriched
Selective
Differential
IF i want to identify acid fast, what agar?
If i want to identify fungi, what agar?
Lowenstein Jensen’s Agar
Sabouraud’s dextrose agar
Agar used for bacteria, IS DIFFERENTIAL and will show you homolysis.
Blood Agar
Overcooked blood agar, doesn’t show homolysis, for Haemophilus and Neisseria.
Chocolate agar, fastidious bacteria
What only grows Neisseria?
Thayer-Martin
This agar grows gram negative rods, but not all of them.
MacConkey Agar
What agar grows staphylococci? Won’t grow strep?
Mannitol salt
What agar rules out TB?
Lowenstein-Jensen
What grows fungi?
Sabouraud Agar
What is an example of most common coagulase negative staph?
Staph epidermidis (USUALLY CONTAMINANT) very common skin contaminant
Do not clean arm for blood cultures with what? we instead use what?
Dont use alcohol
Use ETOH because it can cause contaminant of coagulase negative staph. (important)
Why do you try to minimize exposure to air with wound cultures?
Wound cultures often have anaerobes (cannot tolerate oxygen).
_________ is caused by chlamydia in the conjunctiva causing scaring and affecting the eyelids, the eye lids then lay on the cornea (entropia) which can scar the cornea.
Trachoma
OBJ!
Developed countries: whats the leading cause of death?
Developing countries: whats the leading cause of death?
Coronary Heart Disease (CHD)
Lower respiratory infection (LRI)
Bacteria is being __________ where the broth is clear. Minimal drug used to kill the bacteria is __.
inhibited
1
MIC is what?
MBC is what?
NO visible growth
MBC is dead (MBC not usually given from hospitals, and can never be more than MIC)
This probes for antigen with a single labeled antibody
Direct ELISA
This probes for antibody to an antigen… labeled antibody binds to an unlabeled antibody.
Indirect ELISA
Antigen is “sandwiched between 2 antibodies.
Sandwich ELISA (most common)
Best liver test?
ALT
Kidney function test?
BUN and Creatinine
