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134 Cards in this Set

  • Front
  • Back
Micro from FA:

Alcoholic vomits gastric contents and develops foul-smelling sputum.

Organism type?
Micro from FA:

Middle aged man presents with acute-onset monoarticular joint pain and bilateral Bell's palsy.

What is the likely disease and how did he get it?
Lyme disease, bite from Ixodes tick
Micro from FA:

UA of a pt shows WBC casts.

What is the diagnosis?
Micro from FA:

Patient presents with "rose gardeners" scenario (thorn prick with ulcers along lymphatic drainage)

What is the infectious bug?
Sporothrix schenckii
Micro from FA:

25 yo medical student has a buring feeling in his gut after meals.
Biopsy of gastric mucosa shows gram-neg rods.

What is the likely organism?
Helicobacter pylori
Micro from FA:

32 yo male has "cauliflower" skin lesions. Tissue biopsy shows broad based yeast.

What is the likely organism?
Micro from FA:

Breast-feeding women suddenly develops redness and swelling of her right breast. On examination it is found to be a fluctuant mass.

What is the diagnosis?
Mastitis caused by S.aureus
Micro from FA:

20yo college student presents with lymphadenopathy, fever, and hepatosplenomegaly.

His serum agglutinates sheep RBCs

What cell is infected?
B cell (EBV: infectious mononucleosis)
Micro from FA:

One hour after eating custard at a picnic, a whole family began to vomit. After 10 hrs they were better.

What is the organism?
S.aureus (produces preformed enterotoxin)
Micro from FA:

Infant becomes flaccid after eating honey.

What organism is implicated and what is the MOA?
Clostridum botulinum causes inhibited release of ACh
Micro from FA:

Man presents with squamous cell CA of the penis.

He had exposure to what virus?
Micro from FA:

Patient develops endocarditis three weeks after receiving a prosthetic heart valve.

What organism is suspected?
S.epidermis or S.aureus
Micro from FA:

55yo man who is a heavy smoker and a heavy drinker presents with a new cough and flulike symptoms. Gram stain shows no organisms; silver stain of sputum shows gram neg rods.

What is the dx?
Micro from FA:

After taking clindamycin, patient develops toxic megacolon and diarrhea.

What is the mechanism of diarrhea?
Clostridum difficile overgrowth
Micro from FA
Function and chemical composition of:

Gives rigid support, protects against osmotic pressure

Sugar backbone with cross-linked peptide side chains
Micro from FA
Function and chemical composition of:

Cell wall/cell membrane
Major surface antigen seen in GRAM POSITIVES

Made of: teichoic acid that induces TNF and IL-1
Micro from FA
Function and chemical composition of:

Outer membrane
Major surface antigen of GRAM NEGATIVES
Site of endotoxin (lipopolysaccaride)

Made of lipid A which induces TNF and IL-1
Micro from FA
Function and chemical composition of:

Plasma membrane
Site of oxidative and transport enzymes

Made of a lipoprotein bilayer
Micro from FA
Function and chemical composition of:

(ex of different composition)
Protects against phagocytosis

Made of polysaccaride (except for Bacillus anthracis, which contains D-glutamate)
Micro from FA
Function and chemical composition of:

Space between cytoplasmic membrane and outer membrane in gram-neg bacteria

Contains many hydrolytic enzymes, including beta-lactamases
Micro from FA
Function and chemical composition of:

Mediates adherence of bacteria to cell surface;
sex pilus froms attachment between two bacteria during conjugation.

Made of glycoprotein
Micro from FA
Function and chemical composition of:

Provides resistance to dehydration, heat, and chemicals

Made with a keratin-like coating and dipicolinic acid
Micro from FA
Function and chemical composition of:

What is a plasmid?
Contains a variety of genes fro antibiotic resistance, enzymes, and toxins

Made of DNA
Micro from FA
Function and chemical composition of:

Mediates adherence to surfaces, especially foreign surfaces (indwelling catheters)

Made of polysaccaride
Micro from FA
Function and chemical composition of:

IgA proteases
Allows some organisms to colonize mucosal surfaces:
S.Pneumo, N.Menigitis, N.Gonorrhea, H.Influenza
Micro from FA

What cell wall component is unique to gram neg? gram post?
Gram neg: endotoxin/LPS membrane (outer membrane)

Gram pos: teichoic acid (cell wall)
Micro from FA

What five cellular components are common to both gram pos and gram neg?
Cytoplasmic memb
Micro from FA

What six bugs don't gram stain well?
Treponema (too thin to be visualized)
Rickettsia (intracellular parasite)
Mycobacteria (high-lipid-content cell wall requires acid-fast stain)
Mycoplasma (no cell wall)
Legionella pnuemophilia (primary intracellular)
Chlamydia (intracellular parasite; lacks muramic acid in cell wall)
Micro from FA

Describe the lag, log, stationary, and death curve of bacterioal growth curve?
Lag: metabolic activity without division

Log: rapid cell division

Stationary: nutrient depletion slows growth

Death: prolonged nutrient depletion and buildup of waste products lead to death
Micro from FA

Source of exotoxins and endotoxins?
Exotoxins: certain species of some gram-neg and gram-positive bacteria

Endotoxins: cell wall of most gram-neg bacteria
Micro from FA

Are exotoxins and/or endotoxins secreted from cell?
Exotoxins: yes

Endotoxins: no
Micro from FA

What are exotoxins and endotoxins made of?
Exotoxins: polypeptide

Endotoxin: lipopolysaccaride
Micro from FA

What is the location of genes of an endotoxin? exotoxin?
Endo: bacterial chromosome

Exotoxin: plasmid or bacteriophage
Micro from FA

Describe the differences in toxicity between exotoxins and endotoxins
Exotoxins are highly toxic

Endo-very low
Micro from FA

Describe the differences in antigenicity of exotoxins and endotoxins?
Exotoxins: highly antigenic

Endotoxins: poorly antigenic
Micro from FA

Can toxiods from endotoxins and exotoxins be used in vaccines?
Exotoxins toxoids can be used in vaccines

Endotoxin toxoids: no toxoids are formed so they are not available
Micro from FA

Compare the heat stability of exotoxins and endotoxins?
Exotoxins: destroyed rapidly at 60C (except for staph enterotoxin)

Endo: stable up to 100C for 1hr
Micro from FA

Three typical diseases caused by exotoxins?
Micro from FA

Most common cause of endotoxin induced sepsis?
Micro from FA
Bugs with exotoxins

Two bugs with superantigens? What are superantigens?
Superantigens: bind directly to MHC II and T-cell receptor, activating large numbers of T-cells to stimulate release of IFN-gamma and IL-2

S.Aureus: TSST-1, entertox SE-A (food), ET A and B (skin wound infections)

S.Pyogenes: TSLS from exotoxin A (cellulitis), exo B (necrotizing fascitis), exo C (A,B,and C - scarlett fever post-pharyngitis)
Micro from FA

What do ADP ribosylating A-B toxins do and what four bacteria use them?
ADP ribosylating A-B:
Interfere with host cell function.
B (binding) component binds to a receptor on surface of host cell, enabling endocytosis.
A (active) component then attaches an ADP-ribosyl to a host cell protein (ADP ribosylation), altering protein function.

Corynebacterium diphtheriae
Vibrio cholerae
Bordetella pertussis
Micro from FA

ADP ribosylating A-B toxins of Corynebacterium diphtheriae:
Inactivates elongation factor (EF-2); similar to Pseudomonas exotoxin A

Causes pharanygitis and "psuedomembrane" in throat
Micro from FA

ADP ribosylating A-B toxins of Vibria cholera?
ADP ribosylation of G protein stimulates adenylyl cyclase;
increases pumping of Cl- and H2O into gut
Causes voluminous rice-water diarrhea (not blood)
Micro from FA

ADP ribosylating A-B toxins
of E.Coli?
E.Coli: heat-liable toxin stimulates adenylate cyclase (cholera-like mechanism), causing watery diarrhea.
Heat-stable toxin stimulates guanylate cyclase.
(similar to beta adrenergic receptor G protein increasing cAMP)

"Liable like the air, stable like the ground"
Micro from FA

ADP ribosylating A-B toxins of Bordetella pertussis?
Stimulates adenylate cyclase; cause whooping cough; inhibits chemokine receptor, causing lymphocytosis.
Micro from FA

What toxin does Clostridium perfringens produce?
Clostridum perfringens: alpha toxin causes gas gangrene

Get double zone of hemolysis on blood agar
Micro from FA

What toxin does C.tetani produce?
C.Tetani: blocks the release of inhibitory neurotransmitter glycine; cause "lockjaw"
Micro from FA

What toxin does C.botulinum produce?
C.Botulinum: blocks the release of ACh;
causes anticholinergic symptoms, CNS paralysis especially CN; spores found in canned food, honey (causes floppy baby)
Micro from FA

What toxin does Bacillus anthracis produces?
1-toxin in the toxin complex and it is an adenylate cyclase.
Micro from FA

What toxin does Shigella produce? Other bacteria assoc.
Shiga toxin (also produced by E.Coli O157:H7) cleaves host cell rRNA
Enhances cytokine release, causing HUS
Micro from FA

What other toxin (nonsuperantigen) does S.Pyogenes make?
Streptolysin O is a hemolysin; antigen ASO antibody in rheumatic fever.
Micro from FA

Describe the multiple effects of endotoxins?
Endotoxin is a lipopolysaccharide found in cell wall of gram-neg bacteria.

N-dotoxin is an integral part of gram-Negative cell wall.
Endotoxin is heat stable.

Lipid A: activates macrophages (IL-1, TNF, NO), activates complement (C3a for hypotension and edema, C5a neutrophil chemotaxis), activated Hageman factor (activates coagulation cascade --> DIC)
Micro from FA

What ferments maltose and glucose?
Micro from FA

What ferments just glucose?
Gonococci ferment Glucose
Micro from FA

Produces yellow pigment?
S. Aureus
Micro from FA

Produces blue-green pigment?
Psuedomonas aeruginosa
Micro from FA

Produces red pigment?
Serratia marcescens (thik maraschino cherries)
Micro from FA

Culture requirement for:
H.flu: chocalate agar (with factors V and X)
N.gon: Thayer Martin media
B.Pertussis: Bordet-Gengou potato agar
C.Diphtheriae: tellurite plate, Loffler's medium, blood agar
M.Tuberculosis: Lowenstein-Jensen agar
Micro from FA

What culture is used on lactose fermenting enterics (2 examples)
lactose fermenting enterics: E.Coli, Enterobacter

Pink colonies on MacConkey's agar
Micro from FA

What media does legionella use?
Charcoal yeast extract agar buffered with increased iron and cysteine.
Micro from FA

What media is used to see fungi?
Sabouraud's agar
Micro from FA

What four bacteria use Giemsa stains?
Micro from FA

What two things does PAS stain? What is this used to dx?
Glycogen and mucopolysaccarides

Used to dx Whipples
Micro from FA

Ziehl-Neelsen stain is used to see what?
Acid-fast bacteria
Micro from FA

India ink is used to ID:
Cryptococcus neoformans
Micro from FA

Silver stain is used to see what three things?
Micro from FA

Compare conjugation and transduction?
Conjugation and transduction: both involve only prokaryotic organisms

Conjugation has direct transfer of DNA from cell to cell. And the DNA that is transferred is in either chromosomal or plasmid

In transduction: genes are transfered via a phage and any type of DNA can be used (unless it is "specialized transduction)
Micro from FA

Transformation occurs how and what kind of DNA is used?
Transformation: purified DNA is taken up by a cell

This can occur in prokaryotic and eukaryotic cells and it uses any DNA.
Micro from FA

What is transposition?
When DNA is transferred to same or another chromosome or plasmid within a cell.

This can occur using prokaryotic or eukaryotic cells and DNA SEQUENCES are used ("jumping genes")
Micro from FA

What is lysogeny and what four bacteria posses it?
Genetic code for bacterial toxin encoded in a lysogenic phage.

Botulinum toxin
Cholera toxin
Diphtheria toxin
Erythrogenic toxin of Strept pyogenes
Micro from FA

What are obligate aerobes?
Obligate aerobes use an O2 dependant system to generate ATP.

Psuedomonas aeruginosa
Mycobacterium tuberculosis

Nagging Pests Must Breathe
Micro from FA

Describe the characterisitics of obligate anaerobes?
They lack catalase and/or superoxide dismutase and thus are susceptible to oxidative damage.
Foul smelling (short-chain fatty acids)
Difficult to culture
Produce gas in tissue (CO2 and H2)

They are normal flora in GI tract.

AminO2glycosides are ineffective against anaerobes because these antibiotics requires O2 to enter into bacterial cells.

What are the four lactose fermenting enteric bacteria?
Lactose is KEE


Compare Salmonella and Shigella:
Both are lactose non-fermenters; both invade intestinal mucosa and can cause bloody diarrhea.

Only salMonella is Motile and can invade further and disseminate hematogenously.

Symptoms of Salmonella may be prolonged with antibiotic treatments, and there is typically a monocyte response.

Shigell is more virulent than Salmonella

"Salmon swim (motile and disseminate). Salmonella has an animal reservoir; Shigella does not and is transmitted via "Food, Fingers, Feces, and Flies"

What is a bacteria that is common in daycare outbreaks?
Yersinia enterocolitic

Usually transmitted from pet feces (eg puppies), contaminated milk, or pork.

Can mimic Crohn's or appendicitis

What 8 bugs cause food poisoning?
1. Vibro parahemolyticus and V.Vulnificus - contaminated seafood
2. Bacillus cereus: reheated rice
3. S.Aureus: in meats, mayonnaise, custard (food poisoning starts quickly and ends quickly)
4. C.Perfringens: reheated meat dishes
5. C.botulinum: improperly canned foods (bulging cans)
6. E.Coli 0157:H7 in undercooked meat
7. Salmonella: poultry, meat, and eggs

Bugs causing bloody diarrhea: (8)
Bloody diarrhea:
1. Campylobacter: comma- or S-shaped organisms; growth at 42 degrees; oxidase positive

2. Salmonella: motile, lactose neg

3. shigella: nonmotile, lactose neg, very low ID50; causes dysentery

4. Enterohemorrhagic E.Coli: shiga-like toxin; can cause HUS

5. Enteroinvasive E.coli: O157:H7, invades colonic mucosa

6. Yersinia enterocolitica: day-care outbreaks, psuedoappendicitis

7. C.Diff: pseudomembraneous colitis

8. Entamoeba histolytica: protozoan

Four cAMP inducer bacteria:
1. Vibrio Cholerae (toxin perminantly activates Gs causing rice water diarrhea)

2. Pertussis toxin: permanently disables Gi causing whooping cough. It also promotes lymphocytosis by inhibiting chemokine receptors.

3. EColi: heat liable toxin (first three toxins act via ADP ribosylation that permanently activates adenyl cyclase) --> increases cAMP

4. Bacillus anthracis toxin is composed of an edema factor, a bacterial adenylate cyclase (increases cAMP)

"Cholera toxin that "on" on
Pertussis turns the "off" off"
Parasite hints:

Brain cysts, seizures
Taenia solium (cysticercosis)
Parasite hints:

Liver cysts
Echinococcus granulosus
Parasite hints:

B12 deficiency
Diphyllobothrium latum
Parasite hints:

Paragonimus westermani
Parasite hints:

Portal HTN
Schistosoma mansoni
Parasite hints:

Hematuria, bladder CA
Schistosoma haematobium
Parasite hints:

Microcytic anemia
Ancylostoma, Necator
Parasite hints:

Perianal pruritus

Tricky T's: compare

Chlamydia TRACHomatis
TRICHomonas vaginalis
TRICHinella spiralis
Chlamydia TRACHomatis: bacteria, STD

TRICHomonas vaginalis: protozoan, STD

TRICHinella spiralis: worm in undercooked meat

TRYPanosoma: cause of Chagus' disease or African sleeping sickness

TREPonema: spirocete; causes syphilis (T.Pallidum) or yaws (T.Pertenue)

DNA viral genomes
All DNA viruses except the Parvoviridae are dsDNA.

All are linear except papovaviruses and hepadnaviruses (circular)

"All are dsDNA (like our cells), except "part-of-a-virus" (parvovirus) is ssDNA"

RNA viral genome
All RNA viruses except Reoviridae are ssRNA

All are ssRNA (like our mRNA) except "REpeatOvirus" - reovirus is dsRNA

Naked viral genome infectivity
Nake nucleic acids of most dsDNA (except poxviruses and HBV) and (+) strand ssRNA (mRNA) viruses are infectious.

Naked nucleic acids of (-) strand ssRNA and dsRNA viruses are not infectious.

Naked (=nonenveloped) RNA viruses include Calicivirus, Picornavirus, and Reovirus.
(Naked CPR)

Enveloped viruses
Generally, enveloped viruses acquire their envelops from plasma membrane when they exit from cell.

Explain virus ploidy
All viruses are haploid (with 1 copy of DNA or RNA) except retroviruses, which have 2 identical ssRNA molecules (=diploid)

Compare the location of DNA virus replication and RNA virus replication
DNA viruses: all repicate in the nucleus (except poxvirus)

RNA viruses: all replicate in the cytoplasm (except influenza and retroviruses)

Rules and exceptions for DNA viruses
Some general rules: all DNA viruses -
1. are HHAPPPy viruses
(Hepadna, Herpes, Adeno, Pox, Parvo, Papova)

2. are double stranded (except Parvo - single)

3. are linear (except Papovavirus which is circular and supercoiled and Hepadna which is circular and incomplete

4. are icosahedral (except Pox which is circular)

5. replicate in the nucleus (except Pox which carries own DNA dependant RNA polymerase)

What are the six naked DNA viruses?
You need to be naked for PAP smear:


What are the three enveloped DNA viruses


List the 8 live attenuated viruses vaccines:
1. measles
2. mumps
3. rubella
4. Sabin polio
5. VZV (for immunocompromised children)
6. yellow fever
7. small pox
8. adenovirus

What are the for Killed vaccines?
"RIP Always"
1. Rabies
2. Influenza
3. salk Polio
4. hAv

"SalK = Killed"

What are the three egg based vaccines?
FRY and egg

Yellow fever

Name one recombinant viral vaccine:
HBV (antigen = recombinant HBsAG)

What vaccine is most commonly assoc with post vaccine lymphadenitis?
Measles (will see Warthin-Finkeldy giant cells in measles or from live attenuated virus; they are formed from the fusion of lymphocytes)

Exchange of genes between 2 chromosomes by crossing over within regions of significant base sequence homology

When viruses with segmented genomes (eg influenza virus) exchange segments.

This is a high frequency recombination and the cause of worldwide pandemics.

When 1 of 2 viruses that infect the cell has a mutation that results in a nonfunctional protein.
The nonmutated virus "compleemtns" the mutated one by making a functional protein that serves both virus.

Phenotypic mixing
Genome of virus A can be coated with the surface proteins of virus B.
Type B protein coat determines the infectivity of the phenotypically mixed virus.
However, the progeny from this infection has a type A coat and is encoded by its type A genetic material.

Tzanck test
A smear of an opened skin vesicle to detect multinucleated giant cells.

Used to assay for HSV-1, HSV-2, and VZV.

"Tzanck heavens I do not have herpes"

Describe characteristics of HAV:
HAV: RNA picornavirus
ss+RNA, icosahedral, no env
transmitted fecal-oral
short incubation (3wks)
no carriers

"Hep A = Asymptomatic, Acute, Alone (no carriers, naked ssRNA)"

Describe characteristics of HBV:
HBV: (DNA hepadnavirus)
transmitted primarily by parenteral, sexual, and maternal-fetal routes.

Long incubation (3mths)
Reverse transcription occurs
Virion enzyme is a DNA-dependant DNA polymerase

Describe characteristics of HCV
HCV: RNA flavivirus
transmitted primarily via blood and resembles HBV in its course and severity

Common cause of IV drug use hepatitis in the US

Describe characteristics of HDV
HDV (delta agent)
Defective virus that requires HBsAg as its envelop

Describe characteristics of HEV
HEV: (RNA calcivirus)
Transmitted enterically and causes water-borne epidemics
Resembles HAV in course, severity, incubation.
High mortality rate in pregnany women

"Hep E: Enteric, Expectant mothers, Epidemics"
"A and E by fecal-oral route - the vowels hit the bowels"

Both HBV and HCV predispose patients to what:
HBV and HCV predispose a patient to chronic active hepatitis, cirrhosis, and hepatocellular carcinoma.

HIV Immunity:
Homozygous: immunity
Heterozygous: slower course

HIV Immunity:
Mutation that causes a rapid progressioin to AIDS

What are prions?
Prions: infectious agents that do not contain RNA or DNA (consist only of proteins); encoded by cellular genes.

Diseases include Cretzfeldt-Jakob diseae (CJD-rapid progressive dementia), kuru, scrapie (sheep), and "mad cow disease".

Normal prions have an alpha-helix conformation; pathologic prions (like CJD) are beta-pleated sheets.

What are the normal dominant flora of the:
Dental plaque
Skin: s. epidermidis
nose: s. aureus
oropharynx: viridans streptococci
dental plaque: strep mutans
colon: bacteroides fragilis > e.coli
vagina: lactobacillus, colonized by E.coli and group B strep

Describe the progression to HIV encephalopathy:
Occurs late in the course of HIV infection.
Virus gains access to the CNS via infected macrophages.

Forms microglial nodules with multinucleated giant cells

Describe the CSF findings in meningitis: Bacterial, Fungal/TB, Viral?
pressure increases
increase PMN's
increase protein
decrease sugar

Increase pressure
Increase lymphocytes
Increase protein
Decrease sugar

pressure normal to increased
increased lymphocytes
normal protein
normal sugar

If given no other information: what is the cause of osteomyelitis?

Top three causes of UTI's in ambulatory women:
Staph Saprophyticus

Top five causes of UTI's in women in the hospital:

Mneumonic for UTI's and their clinical findings:

Serratia Marcescens: some strains produce a red pigment

Staphylococcus Saprophyticus

E.Coli: leading cause of UTI's and colonies show a metallic sheen on EMB agar

Enterobacter cloacae: often nosocomial and drug resistant

Klebsiella pneumoniae: large mucoid capsule and viscous capsule

Proteus mirabilis: motility causes "swarming" on agar; produces urease; associated with struvite stones (no vaginitis)

Pseudomonas aeruginosa: blue-green pigment and fruity odor; usually nosocomial and drug resistant

Two diagnostic markers for UTI's?
Leukocyte esterase: positive = bacterial

Nitrite test: positive = gram neg.

Compare the clinical findings of these STD's:
Primary syphilis
Genital herpes
Gonorrhea: urethritis, cervicitis, PID, prostatitis, epididymitis, arthritis, creamy purulent discharge

Primary syphilis: painless chancre

Genital herpes: painful penile, vulvar, or cervical ulcers (HSV-2_

Chlamydia: urethritis, cervicitis, conjunctivitis, Reiter's syndrome, PID (note: no peptidoglycan wall so cephalosporins not effective; can't make ATP) - D-K

Trichomoniasis: vaginitis, strawberry colored mucosa (flaggelated with corkscrew motility)

What does lymphogranuloma venereum cause?
STD from C.trachomatis (L1-L3)

rectal strictures

Condylomata acuminata
Causes genital warts and koilocytes.

Caused by HPV 6 and 11

What is a chancroid?
Painful genital ulcer, inguinal adenopathy

Caused by: Haemophilus ducreyi

What STD causes a noninflammatory, malodorous discharge (fishy smell)? Tests?
Gardnerella Vaginalis (postive whiff test, presence of clue cells)

Bug hints:
Pus, empyema
Staph aureus
Bug hints:

Pediatric infection
Haemophilus influenza (including epiglottis)
Bug Hints

Pnuemonia in cystic fibrosis?
Pseudomonase aeruginosa
Bug hints

Branching rods in oral infection
Actinomyces israelii

Currant jelly sputum

Sepsis/meningitis in newborn
group B strep