Fun with oral
What organism causes oral thrush? What does it look like?
BONUS: Can you scrape it off?
Candida Albicans
Oval yeast with a single bud of varying size. Forms both elongated pseudohyphae and true hyphae
Yes! You can scrape it off
What are the viral characteristics of reovirdiae?
Virions are composed of segmented, double-stranded RNA; a double-layered icosahedral nucleocapsid, and are nonenveloped.
The virions contain an RNA-dependent RNA polymerase.
What part of the GI tract does Enteropathogenic E. Coli (EPEC) infect? What does it look like microscopically? (there's a buzz word) What does this do to the cell?
Small intestine
Pedestals on the host cell surface
Destroys the microvilli
What is the most important virulence factor for C. perfringes? What foods can be contaminated with CP?
•Alpha toxin is the most important
–A lecithinase
–Lyses (RBCs, WBCs, platelets, endothelial cells)
–Massive hemolysis increased vascular permeability, tissue destruction (myonecrosis)
–Ingestion of meat products (stews, casseroles, and gravy) “food service germ.”
What treatment is Aeromonas resistant to?
Penicillins, most cephalosporins, and erythromycin.
What organism can cause protrusion of the eye?
Zygomycosis (Mucormycosis)
What is the viral protein associated with rotavirus? What type of toxin is it and what does it cause?
NSP4: virus protein which serves as an enterotoxin and it prevents absorption of water
What do the Heat-labile toxin (LT) and heat-stable toxin (ST) do inside the cell for ETEC? What is a common issue that is mainly caused by ETEC?
HT and ST both lead to Cl- export and hyper-secretion of H2O (watery diarrhea)
Traveler's diarrhea
What are the viral characteristics of C. diff? What are the virulence factors? (Sorry this question sucks)
•Gram-positive, spore-forming rod. Strict anaerobe (vegetative cells are extremely oxygen sensitive)
•Enterotoxin (toxin A)
–Promotes fluid secretions and intestinal hemorrhage, induces cytokine production
•Cytotoxin (toxin B)
–Damages mucosal membranes
•Adhesion factor
–Binds to human colon cells
•Spores highly resistant
What is the #1 cause of gastroenteritis? What are the characteristics of it? What do we catch it from?
Campylobacter
Gram-negative, Helical (spiral or curved) morphology, Microaerophilic atmospheric requirements
Poultry, unpasteurized milk, or improperly treated water
What are the 3 necessary requirements for the formation of dental caries?
–Cariogenic bacteria
–Sugar
–Teeth
What family is Norovirus in and what are the viral characteristics? Where would one likely get this viral illness?
Caliciviridae
Nonsegmented, (+) ssRNA; an icosahedral nucleocapsid, and are nonenveloped.
Cruise ships (and schools, camps, hospitals, and nursing homes)
Which E. Coli strand is associated with diarrhea lasting >14 days? What part of the body does it infect?
Enteroaggregative E. coli (EAEC)
Small intestine
What are the two types of illnesses that B. cereus produces and what enterotoxins are associated with them?
•Emetic form
–HEAT-STABLE ENTEROTOXIN
–Associated with FRIED RICE
–Abdominal cramps and vomiting
–Incubation period of 1 to 5 hours
–Resolves in 9 hours
•Diarrheal syndrome
–HEAT-LABILE ENTEROTOXIN
–Associated with MEAT, POULTRY, AND SOUPS, CREAM SAUCE
–Incubation period of 8 to 16 hours
–Fever uncommon
–Resolves within 24 hours
What is Reiter's syndrome caused by and what are the symptoms?
•Shigella, Salmonella, Yersinia, Campylobacter
•characterized by the triad of arthritis, conjunctivitis, and urethritis
What two subspecies of Strep Viridans is associated with dental caries?
Dental caries are associated with S. mutans and S. sobrinus
What are the 3 ways Norovirus' infection is enhanced?
•Low infectious dose (as few as 10 virions are needed to cause disease).
•Excretion of virus in the stool both before onset of symptoms and for several weeks after recovery.
•Resistance to inactivation by chlorination and to drying in the environment.
What are the virulence factors for Shigella? Does it ferment lactose? Does it produce H2S? Is it sensitive or resistant to bile salts? How does it move through the cytoplasm?
•Virulence: Ipa, Shiga toxin, VirA
•Non-lactose fermenting
•Do not produce H2S
•Resistant to bile salts
Shigella move through the cytoplasm by utilizing actin rocket.
What kinds of foods can you get Staph. food poisoning from and does it matter whether you cook them or not?
•Staphylococcus is salt tolerant and can grow in salty foods like ham
•Enterotoxin A-D (A and D most common)
–From enterotoxin producing strains contaminating rich foods (mayonnaise, custards, ice cream)
•Staphylococcal toxins are resistant to heat and cannot be destroyed by cooking
What's the drug of choice for C. perifringens?
Penicillin
What are the 3 main organisms that cause peridontal disease and what kind of viruses are they?
•Actinomyces viscosus
–Gram-positive, non-acid-fact, facultative, catalase-positive, filamentous, or diphtheroidal microorganism
•Actinobacillus
–Gram-negative, immotile and nonspore-forming, oval to rod-shaped bacteria
•Bacteroides spp.
–Gram-negative, obligately anaerobic, non-endospore-forming bacilli
What are the important serotypes to know with Adenoviridae?
•Serotypes 40 and 41 are usually associated with “infant diarrhea” (usually older children than those infected with rotaviruses)
•Serotype 42 - sometimes associated with gastroenteritis
What foods can you get Salmonella from? Does it ferment lactose? Does it produce H2S? Is it sensitive or resistant to bile salts?
Meat, unpasteurized milk, raw poultry, fresh produce, and cantaloupe
•Lactose-negative
• H2S-producing
•Resistant to bile salts
Is Listeria catalase positive or negative? Explain its motility. What test can you do to identify it? What does listeriolysin do? Last but not least, does it grow at high or low temperatures?
Catalase positive
•"umbrella" type motility in hanging drop preparations AND actin rockets - protein that mediates actin-directed motility
CAMP test
It allows the organism to escape from the phagosome
Low!! In your fridge
What two illnesses does C. diff cause?
–Antibiotic-associated diarrhea
–Pseudomembranous colitis