Usmle - Micro

Front 1

What in gram positive bacteria induces TNF and IL-1?

Back 1

Teichoic acid

Front 2

What in gram negative bacteria induces TNF and IL-1?

Back 2

Lipid A from LPS (outer membrane)

Front 3

Which bacteria has no cell wall?

Back 3

Mycoplasma

Front 4

What do you use to culture H. influenzae?

Back 4

Chocolate agar with factors V (NAD+) and X (hematin)

Front 5

What do you use to culture M. tuberculosis?

Back 5

Lowenstein-Jensen agar

Front 6

What do you use to culture fungi?

Back 6

Sabouraud's agar

Front 7

What bacteria are intracellular?

Back 7

Rickettsia, Chlamydia, and Legionella

Front 8

Which bacteria are encapsulated?

Back 8

Klebsiella, Salmonella, Streptococcus Pneumoniae, Haemophilus influenzae, and Neisseria meningitidis.

Diagonised with a positive quelling reaction

Front 9

What is the only gram positive bacteria with endotoxin?

Back 9

Listeria monocytogenes

Front 10

What test is used to detect a recent S. pyogenes infection?

Back 10

ASO titer

Front 11

Glycocalyx

Back 11

For bacteria, this mediates adherence to surfaces, especially foreign surfaces (indwelling catheters).

Front 12

Teichoic acid

Back 12

Unique to cell wall of gram positive organisms. Induces TNF and IL-1.

Front 13

Outer membrane

Back 13

Lippopolysaccharide. Unique to cell wall of gram negative organisms. Lipid A induces TNF and IL-1.

Front 14

What bacteria have unusual cell membranes/walls and what is unusual?

Back 14

Mycoplasma - contains sterols and has no cell wall

Mycobacteria - contains mycolic acid and has a high lipid content

Front 15

Which bacteria do not gram stain well?

Back 15

Treponema, Rickettsia, Mycobacteria, Mycoplasma, Legionella pneumophila, and Chlamydia.

These Rascals May Microscopically Lack Color.

Front 16

What stain is used for Cryptococcus neoformans?

Back 16

India ink

Front 17

What stain is used for Legionella?

Back 17

Silver stain; also used for fungi

Front 18

What culture media is used for H. influenzae?

Back 18

Chocolate agar with factors V (NAD+) and X (hematin).

Some CHOCOLATE from the five (V) and dime (X) will make that FLU feel better.

Front 19

What culture media is used for M. tuberculosis?

Back 19

Lowenstein-Jensen agar

Front 20

What culture media is used for fungi?

Back 20

Sabouraud's agar

Front 21

What is MacConkey's agar?

Back 21

Used for lactose fermenting enterics; fermentation produces acid, turning plate pink); bile salts and crystal violet inhibit gram + growth.

Front 22

What bacteria are obligate aerobes?

Back 22

Nocardia, Pseudomonas, Mycobacterium tuberculosis, and Bacillus

Nagging Pests Must Breath.

Front 23

What bacteria are obligate anaerobes?

Back 23

Clostridium, Bacteroides (found in gut), and Actinomyces = Anaerobes Can't Breath Air.

They lack catalase and/or superoxide dismutase and are thus susceptible to oxidative damage. Aminoglycosides are ineffective b/c these antibiotics require O2 to enter the bacterial cell.

Drugs of choice - clindamycin and metronidazole

Front 24

What bacteria are obligate intracellular?

Back 24

Rickettsia, Chlamydia - can't make either own ATP

also Legionella

Stay inside because it's Really Cold (and Legionella).

Front 25

Which bacteria are encapsulated?

Back 25

Klebsiella pneumoniae, Salmonella, Streptococcus pneumoniae, Haemophilus influenzae type B, and Neisseria meningitidis.

Kapsules Shield SHiN

SHiN can produce IgA protease, cause meningitis, and take up DNA from the environment.

Front 26

Staph aureus alpha-toxin

Back 26

Causes hemolysis

Front 27

Staph aureus beta-toxin

Back 27

Sphingomyelinase

Front 28

Staph aureus proteins A, B, and C of gamma toxin

Back 28

A+B = hemolysin
B+C = leukocidin

Front 29

Staph aureus TSST-1

Back 29

Causes toxic shock syndrome; release of cytokines

Front 30

Staph aureus exfoliative toxin

Back 30

Causes scalded skin syndrome

Front 31

What toxins are secreted by Streptococcus pyogenes (group A step)? What is the action of each?

Back 31

Streptolysin O - hemolysis; oxygen labile

Steptolysin S - hemolysis; oxygen Stable

Erythrogenic/pyrogenic toxins - skin rash and fever of scarlet fever

Front 32

What do ASO titers detect?

Back 32

Group A streptococcus (AntiStreptolysin O); used to detect rheumatic fever.

Front 33

Superantigens

Back 33

Bind directly to MHC II and T-cell receptors simultaneously, activating large numbers of T cells to stimulate release of INF-gamma and IL-2.

Front 34

ADP ribosylating A-B toxins

Back 34

ADP ribosylating A-B toxin

Interferes 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 protein (ADP ribosylation), altering protein function.

Front 35

Corynebacterium diphtheriae toxin

Back 35

ADP ribosylating A-B toxin

Inactivates elongation factor (EF-2); causes pharyngitis and "pseudomembrane" in throat. Do not scrape pseudomembrane; this will cause the toxin to go systemic and affect protein synthesis in the heart and brain.

Front 36

Vibrio cholerae toxin

Back 36

ADP ribosylating A-B toxin

ADP ribosylation of G protein stimulates adenylyl cyclase, increasing Cl pumping into the gut and decreasing Na absorption. H2O moves into gut lumen; causes voluminous rice-water diarrhea.

Front 37

E. coli toxin

Back 37

ADP ribosylating A-B toxin

ETEC; Heat-labile toxin stimulates adenylate cyclase; heat-stable toxin stimulates guanylate cyclase. Both cause watery diarrhea.

Labile like the Air, Stable like the Ground.

Front 38

Bordetella pertussis toxin

Back 38

ADP ribosylating A-B toxin

Increases cAMP by inhibiting Galpha1 (Gi); causes whooping cough; inhibits chemokine receptor, causing lymphocytosis.

Front 39

Clostridium perfringens toxin

Back 39

Alpha toxin causes gas gangrene; get double zone of hemolysis on blood agar.

Front 40

C. tetani toxin

Back 40

Blocks the release of GABA and glycine; causes "lockjaw".

Front 41

Bacillus anthracis toxin

Back 41

Edema factor, part of the toxin complex, is an adenylate cyclase.

Front 42

Shigella toxin

Back 42

Shiga toxin (also part of E. coli O157:H7) cleaves host cell rRNA (inactivates 60S ribosome); also enhances cytokine release, causing hemolytic uremic syndrome.

Front 43

Mutated CMV DNA polymerase or lack of viral protein kinase

Back 43

Ganciclovir Resistance

Front 44

What organisms are most commonly implicated in subacute endocarditis?

Back 44

Streptococcus viridans, staphylococcus epidermidis, enterococci

Front 45

What is the most common aerobic skin flora?

Back 45

Staphylococcus epidermidis

Front 46

What 4 conditions is Streptococcus pneumoniae the most common cause of?

Back 46

Meningitis, Otitis media, Pneumonia, Sinusitis

S. pneumo MOPS are Most OPtochin Sensitive

Associated with "rusty" sputum, sepsis in sickle cell anemia and splenectomy.

Front 47

What bacteria are most responsible for neonatal death?

Back 47

Group B strep, E. coli, and Listeria

Front 48

What is the pathogenesis behind rheumatic fever?

Back 48

Antibodies against M protein enhance host defenses against S. pyogenes but can give rise to rheumatic fever.

Front 49

What bacteria form spores?

Back 49

Only certain gram positive rods form spores - Bacillus anthracis, Clostridium perfringens, Clostridium tetani, Bacillus cereus, C. botulinum, and Coxiella burnetti.

Front 50

What antibiotic use is most likely to result in C. diff superinfection? What is the treatment?

Back 50

Clindamycin or ampicillin

Treatment is metronidazole or oral vancomycin.

Front 51

What is a toxicity of methicillin?

Back 51

Hypersensitivity and interstitial nephritis

Front 52

Coinfection of N. gonnorhea and C. trachomatis is common. What antibiotics should be given to cover both?

Back 52

N. gonnorhea - ceftriaxone or fluoroquinolone

C. trichomatis - azithromycin or doxycycline

Front 53

Which bugs are covered by cephalexin or cefazolin?

Back 53

First gen cephalosporins

Gram positive cocci and PEcK (Proteus, E. coli, and Klebsiella)

Front 54

Which bugs are covered by cefprozil?

Back 54

Second generation cephalosporins

Gram positive cocci plus HEN PEcKS

H. flu type B, Enterobacter, Neisseria, Proteus, E. coli, Klebsiella, Serratia

Front 55

Which bugs are covered by cefdinir and ceftriaxone?

Back 55

Serious gram negative infections resistant to other beta lactams; meningitis (S. pneumo), pseudomonas, gonorrhea.

Front 56

What bugs are covered by cefepime?

Back 56

Fourth generation cephalosporin

Increased activity against gram positive organisms and Pseudomonas

Front 57

What stain would you use for Treponemes?

Back 57

Darkfield microscopy and fluorescent antibody staining

Front 58

Antibodies to which protein of Streptococcus pyogenes (group A streptococci) enhance host defenses but can give rise to rheumatic fever?

Back 58

M protein

Front 59

What is the function of protein A of staph aureus?

Back 59

Binds Fc region of Ig. Prevents opsonization and phagocytosis.

Front 60

What is the MOA for Vibrio cholerae toxin?

Back 60

Permanently activates Gs, increasing cAMP, and causing rice water stools.

Front 61

What is the MOA for Vibrio pertussis toxin?

Back 61

Permanently disables Gi, increasing cAMP, and causing whooping cough.

Front 62

What is the MOA of Bacillus anthracis toxin?

Back 62

Bacillus anthracis toxin includes edema factor, a bacterial adenylate cyclase (increases cAMP).

Front 63

What are the symptoms of rheumatic fever?

Back 63

No "rheum" for SPECCulation:

Subcutaneous plaques, Polyarthritis, Erythema marginatum, Chorea, and Carditis

Front 64

Which type of steptococcus can grow in 6.5% NaCl?

Back 64

Enterococci

Front 65

Which bacteria is associated with bacteremia and subacute endocarditis in colon cancer?

Back 65

Streptococcus bovis

Front 66

What medium is used to grow diphtheria?

Back 66

Tellurite agar

Front 67

Which bacteria form spores?

Back 67

Only certain gram positive rods - Bacillus anthracis, Clostridium perfringens, C. tetani, B. cereus, and C. botulinum.

Spores have dipicolinic acid in their core.

Front 68

Tetanospasmin

Back 68

An exotoxin produced by Clostridium tetani which blocks glycine release from Renshaw cells in the spinal cord. Causes spastic paralysis, trismus (lockjaw), and risus sardonicus.

Front 69

What is the only bacteria with a polypeptide capsule?

Back 69

Bacillus anthracis has a capsule that contains D-glutamate.

Front 70

What is the only gram positive bacteria with endotoxin?

Back 70

Listeria

Front 71

What are the possibilities if a PPD comes back positive?

Back 71

Current TB infection, past TB infection, or BCG vaccination

Front 72

Mycobacterium kansasii

Back 72

Found in patients with chronic bronchitis or COPD; produces TB like pulmonary symptoms.

Front 73

Mycobacterium avium intracellulare

Back 73

Often resistant to multiple drugs; causes disseminated disease in AIDS.

Front 74

Mycobacterium scrofulaceum

Back 74

Causes cervical lymphadenitis in children.

Front 75

Mycobacterium marinum

Back 75

Aquatic; causes osteomyelitis, arthritis, and cellulitis in patients that work in shipyards or aquarium handlers.

Front 76

What is the reservoir for Mycobaterium leprae in the United States?

Back 76

Armadillos

Front 77

What is the treatment for Hansen's disease?

Back 77

Leprosy; treatment is long term oral dapsone (toxicity is hemolysis and methemoglobinemia). Alternate treatments include rifampin and combination of clofazimine and dapsone.

Front 78

What would you give for prophylaxis in close contracts with someone who had contracted meningococcus infection?

Back 78

Rifampin

Front 79

What causes pontiac fever?

Back 79

Legionella pneumophila; it is a mild flu-like syndrome.

Front 80

What are the toxins produced by Pseudomonas?

Back 80

endotoxin (fever, shock) and exotoxin A (inactivates EF-2)

Front 81

Which strain of E. coli causes bloody diarrhea and fever?

Back 81

EIEC

Front 82

Salmonella typhi

Back 82

Causes typhoid fever - fever, diarrhea, headache, rose spots on abdomen. Can remain in the gallbladder chronically.

Front 83

Yersinia enterocolitica

Back 83

Usually transmitted from pet feces, contaminated milk, or pork. Outbreaks are common in day-care centers. Can mimic Crohn's or appendicitis, especially in adolescents.

LLQ or RLQ pain with fever.

Front 84

Which bacteria are spirochetes?

Back 84

BLT

Borrelia, Leptospira, and Treponema

Front 85

Treponema pertenue

Back 85

Causes yaws - infection of the skin, bone, and joints, healing with keloids, and severe limb deformities after 5-10 years. Disease of the tropics. Not an STD, but VDRL positive.

Front 86

What are the symptoms of congenital syphilis?

Back 86

Saber shins, saddle nose, CN VIII deafness, Hutchinson's teeth, mulberry molars, and frontal bossing

Front 87

What causes bacillary angiomatosis?

Back 87

Bartonella hensli

Front 88

What causes undulant fever?

Back 88

Brucella

Front 89

What is the classic triad of Rickettsiae infection?

Back 89

Headache, fever, and rash (vasculitis)

Front 90

What infections cause a rash seen on palms and soles?

Back 90

Coxsackie A infection, Rocky Mountain Spotted Fever, and Syphilis

Front 91

Chlamydia psittaci

Back 91

Causes psitticosis, a lung disease that can spread systemically. Notable for an avian reservoir.

Front 92

Which bacteria has a cell wall that is lacking muramic acid?

Back 92

Chlamydiae species

Front 93

What is the only bacteria whose cell membrane contains cholestrol?

Back 93

Mycoplasma

Front 94

How does congenital toxoplasmosis present?

Back 94

Chorioretinitis, hydrocephalus, and intracranial calcifications