Microbiology Flashcards
What infectious disease is characterized by trismus, risus sardonicus, and opisthotonos? Also, define these terms.
Clostridium tetani
Trismus - Lockjaw
Risus Sardonicus - Raised eyebrows and open grin (think of creepy rhesus monkeys in sketchy)
Opisthotonos - Spasms of extensor muscles leading to back arching
What cells in the spinal cord does tetanus effect?
Renshaw cells
Think wrench-saw
What are the three main symptoms of scarlet fever?
- Strawberry tongue
- Pharyngitis
- Blanching, full-body rash which spares the face. (cheeks will still be flushed, with a circumoral pallor around the mouth (looks relatively pale))
What is the life cycle of malaria species? Which can be dormant?
Female Anopheles mosquito injects sporozoites, they spread to blood stream and enter hepatocytes as trophozoites (cannot infect RBCs). These trophozoites mature into schizonts and rupture, releasing merozoite form. Merozoites invade RBCs -> turn into trophozoites -> schizonts -> rupture to release merozoites in cycles. Sometimes gametocytes are released by schizonts which are taken up by mosquitos.
Food = protein from heme breakdown. Need to form hemozoin to deal with heme rings.
P. vivax (Ax) and P. ovale (shield) can become dormant
What drugs are used to treat regular P. malariae? P. vivax / P. ovale? P. falciparum? Prophyaxis?
P. malariae - chloroquine if susceptible (blocks heme polymerase for hemozoin formation), otherwise mefloquine (me-fly queen)
P. ovale / vivax - same treatment, except add primaquine (primal queen, treats hypnozoite dormant stage)
P. falciparum - use artemisins like artesunate, causes more serious infection
What blood smear can be seen in malaria inside the RBC?
Ring form -> from trophozoite form
What organs does P. falciparum tend to affect and why?
Binds to ICAM-1 receptor on endothelium in brain, kidney, and liver to avoid splenic clearance
- > can cause complications in all these organs, such as cerebral malaria
- > think of gold kidney / lung plates in sketchy
How is Babesia microti transmitted and how can it be differentiated from malaria symptomatically? What is the biggest risk factor for severe disease?
via the Ixodes tic (think of Robin of Ixodes amongst the vampires)
-> fever does not follow regular cycles
Risk factor = sickle cell disease (Severe hemolytic anemia). This is in contrast to malaria, where sickle cell disease is protective.
What is seen in peripheral blood smear of Babesia? How is it treated?
Maltese cross and ring form
Treatment: Atovaquone (vampire queen) + azithromycin (crow on her shoulder)
If an AIDS patient presents with multiple ring-enhancing lesions on CT, what is the most likely diagnosis and why?
Toxoplasma gondii -> most likely to cause mass effect and multiple lesions, much more common than cryptococcoma
C. neoformans is unlikely to be the diagnosis as it causes soap bubble lesions, although it is the most common fungal cause of this.
Aspergillus -> more likely to cause a single abscess.
A primary central nervous system B-lymphoma (due to EBV, associated in AIDS patients) is actually more likely than these fungal causes as a second item on a DDx to Toxoplasmosis
Where in the cell do RNA / DNA viruses replicate and what is the exception to the rule in each of these?
RNA - replicate in the cytoplasm
-> exception: Orthomyxoviruses
DNA - replicate in the nucleus (need an RNA polymerase)
-> exception: Poxviruses -> brings its own RNA polymerase AND makes its own envelope
What are the clinical features of molluscum contagiosum infection?
Dome-shaped, flesh-colored papules all over the body except in palms / soles
- > central umbilication (ulceration in the center)
- > it is a poxvirus, common in children, but can be an STD for adults and will present as one lesion
What pathogens can cause rashes on palms and soles?
Syphilis - Secondary
Rickettsia Rickettsii - RMSF
Coxsackie A virus - Hand, foot, and mouth disease
What childhood exanthem is caused by HHV6, and what cell type does it primarily affect?
Exanthem subitum -> roseola (child holding rosary) -> 4 feathers on his hat for CD4 cell
What are the clinical features of roseola?
Think of the four suns -> 4 day fever, extremely high fever (>104 F) that can cause seizures. Think of the boy seizing.
Think of mother mary with lacy clothes with blue flames -> once the fever has subsided, a diffuse, “lacy”, macular rash will appear all over the body except face
What other virus can cause Roseola? How do you distinguish roseola from measles?
HHV7.
Measles (Rubeola) will have fever and rash at the same time.
What is HHV8 associated with and what does that look like? Who is most susceptible?
Kaposi sarcoma - endothelial neoplasm due to dysregulation of VEGF
- > look like dark violet plaques / nodules, especially on hard palate and extremities
- > seen in AIDS patients / immunocompromised
What other organs are commonly involved in Kaposi sarcoma?
GI tract, lungs
-> think of the colon covering to her flowers at Kate’s Posies
How do you tell Taenia saginata vs Taenia solium apart on stool O and P?
Taenia solium will have hooks around its proglottid head -> remember the hooks around the pig at the carnival
How are Taenia infections normally treated? What if they are in the brain? How do you get a Taenia brain infection?
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Normally -> i.e. intestinal or elsewhere in the body = Praziquantel (pretzel)
Neurocysticercosis -> add albenzazole (bendy bar guy)
-> the EGGS of the cestode (rather than the larvae) must be ingested
What is Diphyllobothrium latum also known as? What is its most memorable side effect?
Bothrium = bathroom in sketchy Fish tapeworm (throwing plate of fish while running towards bathroom) -> largest tapeworm -> competes for B12 (must be 12 to use fireworks) in the intestine, can cause B12 deficiency and megaloblastic anemia (fireworks in background)
What parasite is known to cause liver cysts? What are its definitive and intermediate host?
Echinococcus granulosus, another cestode. Think EchinoCOCKER SPANIEL -> winning the dog show
Definitive: Dogs
Intermediate: Sheep (Sheep dog is #2 in the dog show)
Humans are incidental host
How do the hydatid cysts of Echinoccus appear on CT? Why are they concerning?
Appear as “eggshell calcification” as a liver cyst
- > concerning because if they rupture they can cause anaphylaxis (think of the guy holding a cyst walking next to the dog show with a red face)
- > need to be careful when removing this (vs Entamoeba which you wouldn’t remove)
What is the #1 cause of osteomyelitis in patients with sickle cell disease? What is its primary virulence factor?
Salmonella typhi
Think of the seagull (gall bladder) holding the sickle with the Typhoid Mary apron.
Vi capsule = Virulence capsule, resistance to phagocytosis and opsonization
Why can HSV not undergo reassortment?
Only segmented viruses (i.e. influenza virus) can undergo reassortment
-> HSV viruses can coinfect cells and undergo recombination by crossing over of homologous regions, however
What are the segmented viruses?
All are RNA viruses Include BOAR: Bunyaviruses Orthomyxoviruses Arenaviruses Reoviruses
What are the exotoxins produced via ETEC?
Labile in the Air, Stable on the Ground
- Heat-labile toxin - overactivates adenylyl cyclase -> cAMP increase, Cl- secretion and H20 efflux in gut.
Also called Cholera-like toxin - Heat-stable toxin - overactivates guanylate cyclase -> cGMP increase, decreasing resorption of NaCl and H20
- > causes watery diarrhea overall
What is the function of cord factor in Mycobacterium TB?
It is a mycolic acid derivative required for virulence of TB.
Helps TB form “serpentine cords” with respect to the other TB bacteria. This formation activates macrophages, induces the release of TNF, and inactivates neutrophils. This allows them to be walled off in a granuloma where they can’t be accessed by the rest of the immune system.
Think of the Lasso from the TB cowboy holding onto the macrophage cart driver
What virulence factor inhibits phagolysosome fusion in TB? How does it work?
Sulfatides -> surface glycolipids of TB. These glycolipids are released and cause secondary lysosomes to become incompetent, inhibiting fusion with the phagosome containing TB.
What microbe is typically the cause of bilateral adrenal gland hemorrhaging?
Waterhouse-Friderichesen syndrome, a complication of Neiserria meningitidis bacteremia which can occur without meningitis.
Also causes fever, disseminated intravascular coagulation, and shock
This is due to extensive vasoconstriction of the adrenals during shock
What causes undulant fever? What is the source and treatment?
Brucella - a zoonosis normally from unpasteurized dairy
Treatment - Doxycycline (remember the bicycle windmill) and rifampin (rifle actually carried by the sick person)
Where does Brucella live? How does this relate to disease course?
Facultative intracellularly in macrophages
Cause cause hepatosplenomegaly and LN enlargement due to its growth in macrophages
What microbe is characterized by a “spaghetti and meatballs” appearance under the microscope?
Malassezia furfur (Tinea versicolor) -> Italian restaurant in sketchy
What are the symptoms of tinea versicolor and what is the treatment? Why does this happen?
Hypo and hyperpigmented spots on skin due to interference with melanocytes via degradation of lipids by acids.
Lives in stratum corneum (think of corn in sketchy)
Treatment = Selsun Blue (blue doorway in sketchy) = Selenium sulfide
What is onychomycosis and what is the treatment?
Another name for tinea unguium or tinea of the nails
Treat with terbinafine (inhibits squalene epoxidase and can cause GI upset) or griseofulvin (inhibits microtubule formation)
What are the treatments for Trypanosoma brucei infection?
Melarsoprol - mela “soap” - in sketchy, for CNS infections
Suramin - sounds like bottle of serum, for blood infection
What are the two forms of Leishmaniasis and where does the protozoa live inside the body?
Visceral (Donovan, black fever “kala-azar”) and Cutaneous (Braziliensis, brazil flag, zombie is flesh-eating)
Protozoa lives as amastigotes inside macrophages (goats in macrophage cages) -> characteristically multiple in macrophages
What are the symptoms of cutaneous and visceral leishmaniasis?
Cutaneous - skin ulcers
Visceral / Kala-Azar - Spiking fevers, pancytopenia (think of pan with RBCs in it), and hepatosplenomegaly (from macrophage involvement). Basically think of infected macrophages crowding out the bone marrow.
What is the treatment for Leishmaniasis? Where is this bug spread?
Cutaneous - T-bone steak = stibogluconate
Visceral - Amphotericin B - think of frogs everywhere in da desert
Spread in Africa / Middle east -> desert area, since it is spread by the sandfly
What infection is especially associated with pigmented gallstones and how do you get it?
Clonorchis sinesis (think orca whale in trematode sketchy)
Get from eating undercooked fish i.e. sushi
Think of the seagull on stack of rocks to remember pigmented gallstones
What cancer is associated with Clonorchis sinensis?
Cholangiocarcinoma -> due to it causing biliary tract inflammation
Think of the seagull having fibrotic rope (biliary tract) grabbed on by crab
What are scabies and how are they spread?
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Mites which burrow into skin and cause a pruritic, erythematous rash
Common in children and teachers, spread via skin to skin contact. Rash can even start on palms
What can be expected to happen if you eat death cap mushrooms (Amanita phalloides)? What is the mechanism of action?
Amatoxin will accumulate in liver cells and cause severe hepatotoxicity -> elevated liver enzymes
-> amatoxin binds RNA polymerase II, stopping mRNA synthesis and leading to apoptosis of the cell
What are the symptoms of deathcap mushroom poisoning?
Delayed onset vomiting and cholera-like diarrhea which will ultimately result in hepatotoxicity and acute renal failure
-> toxin accumulates in cells with rapid cellular turnover
What protein is responsible for the beta-hemolytic properties of Group A Strept?
Streptolysin O (SLO)
What is the capsule of Bacillus anthracis made of?
Poly-D glutamate
-> one of the only bacteria to be made of dis capsule type (protein rather than polysaccharide)
What is the defining characteristic difference between the growth of Clostridia and Bacillus species?
Clostridia -> anaerobes
Bacillus -> aerobes
What is the active ingredient and reversal agent for most rat poisons?
Active ingredient is a 4-hydroxycoumarin derivative called brodifacoum
Give FFP for reversal (Same as warfarin)
What media other than tellurite agar is used for growth of Corynebacterium diphtheriae?
Loeffler’s media
-> think of the boy laughing
What test is used to determine if diphtheria possesses toxins?
Elek’s test
- > think “E-lick” -> Bull’s tongue hanging out
- > basically have a filter paper with antitoxin on it which reacts with the exotoxin of diphtheria
What type of vaccine is diphtheria?
Toxoid -> inactivated toxin. Remember this because the syringe sticking out of the bull is green, same as the green bow-tie, indicating it is a vaccine of the toxin
part of the TDaP vaccine
Can Listeria cause a transplacental infection? Is it susceptible to cefotaxime?
Yes - causes a transplacental infection
No - not susceptible to cefotAXime or other 3rd generation cephalosporins. This is the reason why ampicillin is added to the treatment regimen of potentially susceptible populations.
Who tends to get Nocardia infection, what are the clinical manifestations, and how is it treated?
Immunocompromised, especially those exposed to glucocorticoids longterm
respiratory - cavitary lesions in lungs mimicking TB (think of bullet cavitating ID badge)
CNS - brain abscesses
skin - cutaneous indurated abscesses
Treatment - sulfonamide eggs
What is Thayer-Martin agar also called and what is it used to isolate?
VPN agar
Vancomycin - inhibit gram +
Polymyxin E (colistin) - inhibit most gram negative
Nystatin - inhibit yeast
Used to isolate Neisseria
What is responsible for the massive inflammatory response to Neisseria?
Think of the burning envelopes in sketchy
-> Lipooligosaccharide (LOS) is like LPS, grows so quickly that it blebs off and activates the immune system
Does Neisseria gonorrhea have a capsule? Why does this matter?
No! Think of the broken glass on the floor in sketchy
-> important because N. meningitidis DOES have a capsule -> makes it more likely in those with sickle cell
What’s the mechanism of action of Shigatoxin?
Inactivates 60S ribosome by removing adenine from rRNA
-> think of 60s hourglass
- > there is NO ribbon in the sketch, so it’s not ADP-RIBOsylating like the E2F (accordian) interaction of diphtheria or pseudomonas.
- > It’s an AB toxin, but does NOT work via ribosylation
What gram negative bug is pretty similar to Listeria and how is it spread? Is it encapsulated / what shape is it?
Yersinia enterocolitica (Think English terrier) -> is resistant to cold temperatures, and is thus able to multiply in stored blood transfusions
Like Listeria, spread via contaminated milk (think of the Toddler holding the bottle of milk), or via pet feces (especially puppies)
It is an encapsulated gram negative organism that exhibits bipolar (safety pin) staining
What problems does Yersinia enterocolitica cause?
RLQ pain due to mesenteric adenitis or terminal ileitis
- > “pseudoappendicitis”
- > think of the puppy licking the child’s RLQ
-> also causes acute bloody diarrhea (think of his red stool)
What is a Yop?
Yersinia outer proteins
-> secreted by Yersinia pestis in a Type 3 secretion system, cause macrophage and neutrophil dysfunction by inhibiting phagocytosis / cytokine production
Worker using Type 3 secretion system to give the rodent water
What is the treatment for Yersinia infections?
Think of the guy holding the psi as well as the rodent bicycle wheel:
aminoglycosides (particularly streptomycin) + tetracycline
What is the treatment for H. pylori?
- PPI - H+ bomb
- Clarithromycin - “Keep clear” crow
- Amoxicillin - ammo box. Metronidazole if allergic
Who is at risk for Pseudomonas osteomyelitis?
IV drug users -> direct hematogenous seeding. Think of the mortar and pestle next to the fishbones in sketchy.
Diabetics -> Think of the candy jar next to the fishbones in sketchy.
What type of vaccine is the Hib vaccine?
Type b capsular polysaccharide polyribosylribitol phosphate, conjugated with diphtheria toxin to increase immunogenicity
What are the clinical features of Legionnaire’s disease?
Smoker presents with high fever, lobar pneumonia, CNS symptoms (sailor getting hit by bucket) including headache / confusion, hyponatremia, and diarrhea
What is the gram morphology of Francisella tularensis? How is it spread?
Gram negative and radish-shaped
Spread via rabbit reservoir or indirect contact via dermacentor tick vector
Describe the disease that Francisella tularensis causes.
Tularemia - Bacteria lives facultative intracellularly inside macrophages (cage). Causes formation of cutaneous ulcer at site of bite, and regional lymphadenopathy with caseating granulomas (think of underground radishes pushing up dirt piles).
What type of immune response is adaptive for leprosy and what will the disease do in this case? Which form is transmissible between humans and how is it spread?
Th1 response - “Tuberculoid” - best response. Well controlled, with some hypoesthetic and hairless skin (think of bald guy) plaques due to peripheral involvement on cold parts of extremities. Can be confirmed via Lepromin skin test.
Th2 response - “Lepromatous” - mostly humoral - worst outcome -> respiratory communicable due to poor control. Typically stocking and glove / extensor surface involvement.
What’s the treatment for leprosy?
Tuberculoid form - Dapsone (Deputy) + rifampin (rifle)
Lepromatous form - Add Clofazimine (cloth)
How do you differentiate Chlamydia neonatal conjunctivitis from Gonorrhea?
Chlamydia - presents later, and often accompanied by pneumonia (“Staccato cough”)
Gonorrhea - presents early
What type of arthritis do chlamydia and gonorrhea cause?
Chlamydia - reactive (B27-associated)
Gonorrhea - septic
What are the symptoms of Q fever and what causes it?
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Coxiella burnetti - gram negative closely related to Rickettsia
Fever, retroorbital headache, lobar pneumonia, and granulomatous hepatitis
-> differentiate from Brucella by lack of undulating fever
How does Coxiella grow and how is it transmitted? What heart problem can it cause?
Grows as obligate intracellularly (sheep is locked in)
Transmitted via aerosolized farm animal secretions (feces or amniotic fluid) in its endospore form
Very important cause of culture negative endocarditis.
What agar is used to grow Mycoplasma?
Eaton agar -> don’t “eat on” ice!
What disease does Rickettsia prowazekii cause and how does the rash spread?
Causes epidemic typhus
Just remember Typhus on the Trunk, or how the football coach directs his players from the center outward.
Another major difference from Rickettsia ricketsii is that it spares the palms and soles (football players with white hands)
How is R. prowazekii spread and what are the symptoms?
Spread via lice -> reason is can cause epidemics
Think of being tackled:
Arthralgias and myalgias
Pneumonia - wind knocked out of you
Encephalitis - like being concussed
How large is paracoccidioidomycosis and where do you get it? Symptoms?
South America
It is much larger than RBC (think of the center of the captain’s wheel being red)
Symptoms: pneumonia, cervical lymphadenopathy (white beads), and mucocutaneous lesions (missing teeth)
What fungus causes problems in neonates receiving TPN?
Malassezia -> it loves lipids
Think of the baby holding the piece of spaghetti (represents the catheter)
What are the treatments for Sporothrix?
- Itraconazole - pine cones
2. Potassium iodide - think of the potassium iodide pesticide
What form of Candida exists at 20 and 37 degrees?
Cold - think of the branching plants on the ground (the snow it cold) -> pseudohyphae
Heat - think of the ice cream cone stand - germ tubes -
true hyphae. “37 flavors”
What specialize enzyme does Candida possess that most other fungi do not?
Catalase -> increased risk with chronic granulomatous disease
-> Note that Aspergillus is also catalase positive (think of Cat on top of scarecrow)
At what CD4 count do you start getting a candida infection of the GI tract and what is it?
Esophagitis -> think of the slide
“Max 100 pounds” -> starts at CD4 <100
Normal weight cutoff between children and adults
Who gets candidal endocarditis and why?
IV drug users -> Candida is a common contaminant of heroin.
Think of the three pyramids -> Candida is commonly implicated in tricuspid valve endocarditis.
Who is susceptible to candidal vulvovaginitis and what will the pH be?
- Diabetics
- OCP users
- Antibiotic users
pH will be <4 (unlike Trichomonas or Gardnerella), candida does not change pH. Park is only open til 4pm.
What is the most specific test for Cryptococcus?
Latex agglutination for the polysaccharide capsule (only fungus with this unique polysaccharide capsule)
-> think of the guy with the latex gloves holding the urease bottle over the polysaccharide sarcophagus capsule
