Microbio-Bacterias

Question 0

Bacterial virulence factors - What does IgA protease do? Which organisms secrete it?

Answer 0

Enzyme that cleaves IgA. Secreted by Strep. pneumoniae, H. influenza type B, and Neisseria.

Question 1

Bacterial virulence factors: what does Protein A do? What organism expresses it?

Answer 1

Protein A binds to the Fc Region of IgG. It prevents opsonization and phagocytosis. Expressed by S. aureus.

Question 2

Bacterial virulence factors- role of M protein? It is expressed by which organism(s)?

Answer 2

Helps prevent phagocytosis. Expressed by group A streptococci.

Question 3

What is a type III secretion system, and who uses it? Aka-injectosome (4)

Answer 3

Needle-like protein appendage facilitating direct delivery of toxins from certain G (-) bacteria: pseudomonas, Salmonella, Shigella, E. coli, to eukaryotic host cell.

Question 4

Organism that infects prosthetic devices and intravenous catheters by producing adherent biofilms. Component of normal skin flora; contaminates blood cultures. Novobiocin sensitive.

Answer 4

Staphylococcus epidermidis

Question 5

Organism that is second most common cause of uncomplicated UTI in young women (first E. Coli). Novobiocin resistant.

Answer 5

Staphylococcus saprophyticus

Question 6

Lancet-shaped, gram-positive diplococci. Encapsulated. IgA protease.
Assoc. with appearance of Rusty Colored Sputum, sepsis in sickle cell anemia and splenectomy. No virulence without capsule.

Most common cause of MOPS.

Answer 6

Streptococcus pneumoniae

Question 7

Optochin resistant (vs. S. Pneumoniae), alpha-hemolytic, part of normal flora of the oropharynx and cause dental caries, and subacute bacterial endocarditis at damaged valves.

Answer 7

Viridans group streptococci - Streptococcus mutans, S. Sanguinis.

Question 8

JONES criteria for rheumatic fever. Causes pharyngitis, cellulitis, impetigo. Toxigenic-scarlet fever, toxic shock-like syndrome, necrotizing fasciitis. Immunologic-rheumatic fever, acute glomerulonephritis. Bacitracin sensitive. Antibodies to M protein enhance host defenses. ASO titer detects recent infection.

Answer 8

Streptococcus pyogenes (group A streptococci).

Question 9

Presentation of skin rash with sandpaper-like texture, strawberry tongue, circumoral pallor.

Answer 9

Scarlet Fever

Question 10

Bacitracin resistant, beta-hemolytic, colonized vagina; causes pneumonia, meningitis, and sepsis, mainly in babies. Produces CAMP factor. Screen pregnant women at 35-37 weeks. Patients with positive culture receive intrapartum penicillin prophylaxis.

Answer 10

Streptococcus agalactiae (group B streptococci)

Question 11

Normal part of colonic flora that are penicillin-G resistant and cause UTI, biliary tract infections and subacute endocarditis (following GI/GU procedures). Vancomycin-resistant enterococci are an important cause of nosocomial infection. Can grow in 6.5%NaCl and bile test.

Answer 11

Enterococci (group D streptococci) - Enterococcus faecalis and E. faecium)

Question 12

Colonizes the gut. Can cause bacteremia and subacute endocarditis in colon cancer patients.

Answer 12

Streptococcus bovis- (group D streptococci)

Question 13

(G+) rods- exotoxin encoded by beta-prophage. Potent exotoxin inhibits protein synthesis via ADP-ribosylation of EF-2. Symptoms include pseudomembranous pharyngitis (grayish-white membrane) with lymphadenopathy, myocarditis, and arrhythmias. Black colonies on cysteine-telluride agar.

Answer 13

Corynebacterium diphtheriae

Question 14

Cleaves releasing proteins for neurotransmitters; paralysis from Renshaw cells in spinal cord. Causes spastic paralysis, trismus (lockjaw), and risus sardonicus.

Answer 14

Clostridium tetani

Question 15

Produces a preformed, heat-labile toxin that inhibits ACh release at the NMJ. In adults usually caused by ingestion of preformed toxin in canned foods. In babies, due to ingestion of spores in honey causing floppy baby syndrome. **spore former

Answer 15

Clostrium botulinum

Question 16

Produces alpha-toxin (“lecithinase” a phospholipase) that can cause myonecrosis and hemolysis (gas gangrene). **spore former

Answer 16

Clostridium perfringens

Question 17

Produces 2 toxins- Toxin A, enterotoxin binds to the brush border of the gut. Toxin B, cytotoxin, causes cytoskeletal disruption via actin depolymerization–> pseudomembranous colitis–>diarrhea. Often secondary to antibiotic use. Tx metronidazole or oral vancomycin.

Answer 17

Clostridium dificile

Question 18

G (+) spore forming rod - only bacterium with a polypeptide capsule (contains D-glutamate). Boil like lesion –> ulcer with black eschar –> uncommonly progresses to bacteremia and death.

Answer 18

Cutaneous anthrax - Bacillus anthracis

Question 19

G (+) spore forming rod - only bacterium with a polypeptide capsule (contains D-glutamate). Inhalation of spores –> flu like symptoms that rapidly progress to fever, pulmonary hemorrhage, mediastinitis, and shock. Aka- Woolsorter’s disease.

Answer 19

Pulmonary anthrax

Question 20

Gram (+) Causes food poisoning. Causes watery, non-bloody diarrhea and GI pain within 8 hrs. Associated with reheated rice. **spore former

Answer 20

Bacillus cereus

Question 21

Only G(+), facultatative intracellular microbe that produces LPS; acquired by ingestion of unpasteurized dairy products and deli meats, via transplacental transmission, or by vaginal transmission during birth. –>neonatal meningitis Charac. rocket tails that allow for tumbling mobility. Can cause spontaneous abortions in pregnancy.

Answer 21

Listeria monocytogenes

Question 22

Organism with branching filaments resembling fungi. G(+) Anaerobe, not acid fast, part of normal oral flora, causes oral/facial abscesses that drain through sinus tracts, forms yellow “sulfur granules”. Tx with penicillin

Answer 22

Actinomyces

Question 23

Organism with branching filaments resembling fungi. G(+) Aerobe, weakly acid fast, found in soil, causes pulmonary infections in imunocompromised and cutaneous infections after trauma in immunocompetent. Tx with sulfonamides

Answer 23

Nocardia

Question 24

Acid fast organism. Symptoms include fever, night sweats, weight loss, and hemoptysis. Cord factor in virulent strains inhibits macrophage maturation and induces release of TNF-alpha. Sulfatides (surface glycolipids) inhibit phagolysosomal fusion.

Answer 24

Mycobacterium: M. tuberculosis (TB, often resistant to multiple drugs). M. kansasii (pulmonary TB-like symptoms). M. avium-intracellulare (causes disseminated, non TB disease in AIDS.

Question 25

Acid-fast bacillus that likes cool temperatures (infects skin and superficial nerves - "glove and stocking" loss of sensation) cannot be grown in vitro. Reservoir in US: armadillos. Presents diffusely over the skin, with leonine facies, and is communicable; charac. by low cell-mediated immunity with a humoral Th2 response.

Answer 25

Mycobacterium leprae- Leprosy (Hansen disease) Lepromatous. Tx: clofazimine for 2-5 years

Question 26

Acid-fast bacillus that likes cool temperatures (infects skin and superficial nerves - "glove and stocking" loss of sensation) cannot be grown in vitro. Reservoir in US: armadillos. Limited to a few hypoesthetic hairless plaques; characterized by high cell-mediated immunity with largely Th1-type immune response.

Answer 26

Mycobacterium leprae- Leprosy (Hansen Disease) Tuberculoid - Tx: consists of multi drug therapy: dapsone and rifampin for 6 months.

Question 27

Gram negative diplococci, produces IgA proteases. 2 types:

Answer 27

Neisseria: Gonococci Meningococci

Question 28

Ferments glucose only. No polysaccharide capsule; no maltose fermentation; no vaccine (due to rapid antigenic variation of pious proteins); sexually transmitted, causes gonorrhea, septic arthritis, neonatal conjunctivitis, pelvic inflammatory disease, and Fitz-Hugh-Curtis syndrome. Erythromycin ointment prevents neonatal transmission.

Answer 28

Neisseria gonococci

Question 29

Ferments: maltose and glucose. Polysaccharide capsule; maltose fermentation; vaccine (none for type B), respiratory and oral secretions. Causes meningococcemia and meningitis, Waterhouse-Friderichsen syndrome. Tx: Ceftriaxone or penicillin G. When patient has meningitis, presents with púrpura formation on the skin.

Answer 29

Neisseria: meningococci

Question 30

Small gram-negative (coccobacillary) rod; aerosol transmission. Most invasive disease caused by capsular type B. Produces IgA protease. Culture on chocolate agar with factor V and X (10). Known for epiglottitis (cherry red in children), meningitis, otitis media, and pneumonia. Does NOT cause the flu.

Answer 30

Haemophilus influenzae

Question 31

G(-) rod, stains poorly-use silver stain. Grow on charcoal yeast extract culture with iron and cysteine. Detected clinically with presence of antigen in urine. Aerosol transmission from environmental water source habitat. No person to person transmission. Causes: severe pneumonia, fever, GI and CNS symptoms.

Answer 31

Legionella pneumophila - legionnaires' disease Pontiac fever= mild flu-like syndrome.

Question 32

Aerobic G(-) rod. Non-lactose fermenting oxidase [+]. Produces pyocyanin (blue-green pigment); has a grape like odor. Water source. Produces endotoxin (fever, shock), and exotoxin A (inactivates EF-2). Assoc. w/wound and burn infections, Ecthyma gangrenosum- rapidly growing necrotic tissue, pneumonia in CF, sepsis, external otitis, UTI, drug use, diabetic osteomyelitis, and hot tub folliculitis.

Answer 32

Pseudomonas aeruginosa

Question 33

Virulence factors: fimbriae- cystitis and pyelonephritis; K capsule- pneumonia, neonatal meningitis; LPS endotoxin-septic shock. Microbe invades intestinal mucosa and causes necrosis and inflammation. Clinical manifestations similar to Shigella.

Answer 33

E. Coli- EIEC: invasive; dysentery

Question 34

Virulence factors: fimbriae- cystitis and pyelonephritis; K capsule- pneumonia, neonatal meningitis; LPS endotoxin-septic shock. Produces heat-labile and heat-stable enterotoxins. No inflammation or invasion.

Answer 34

E. coli- ETEC: traveler's diarrhea (watery)

Question 35

Virulence factors: fimbriae- cystitis and pyelonephritis; K capsule- pneumonia, neonatal meningitis; LPS endotoxin-septic shock. No toxin produced. Adheres to apical surface, flattens villi, prevents absorption.

Answer 35

E. coli - EPEC: diarrhea usually in children (pediatrics).

Question 36

Virulence factors: fimbriae- cystitis and pyelonephritis; K capsule- pneumonia, neonatal meningitis; LPS endotoxin-septic shock. O157:H7 is the most common serotype. Produces Shiga-like toxin that causes Hemolytic-uremic syndrome. Microthrombi form on endothelium damaged by toxin--> mechanical hemolysis (schistocytes formed) and decrease renal blood flow; microthrombi consume platelets--> thrombocytopenia.

Answer 36

E. coli - EHEC Dysentery (toxin alone causes necrosis and inflammation). Does not ferment sorbitol (distinguishes it from other E. coli).

Question 37

An intestinal flora that causes lobar pneumonia in alcoholics and diabetics when aspirated. Very mucoid colonies caused by abundant polysaccharide capsules. CF: patient presents Red "currant jelly" sputum. Also cause nosocomial UTIs. 4 A's...

Answer 37

Klebsiella- 4 A's: Aspiration pneumonia Abscess in lungs and liver Alcoholics di-A-betics

Question 38

Organism that does not ferment lactose, can cause bloody diarrhea, invades intestinal mucosa and causes a monocytic response. Antibiotics may prolong fecal excretion of the organism. Produces hydrogen sulfide and has many animal reservoirs. Have flagella and can disseminate hematogenously.

Answer 38

Salmonella

Question 39

Does not ferment lactose, often causes bloody diarrhea, invades mucosa and causes PMN infiltration. Antibiotics shorten duration of fecal excretion of organism. Does NOT produce hydrogen sulfide. Only reservoirs are humans and primates. Cell to cell transmission; no hematogenous spread. No flagella.

Answer 39

Shigella

Question 40

Causes typhoid fever. Found only in humans. Characterized by rose spots on the abdomen, fever, headache, and diarrhea. Can remain in gallbladder and cause carrier state.

Answer 40

Salmonella typhi

Question 41

Major cause of bloody diarrhea, especially in children. Fecal oral transmission through foods such as poultry, meat, unpasteurized milk. Comma or S-shaped, oxidase [+], grows at 42*C. Common antecedent to Guillain-Barré syndrome and reactive arthritis.

Answer 41

Campylobacter jeujuni

Question 42

Produces profuse rice-water diarrhea via enterotoxins that permanently activates Gs, increases cAMP. Comma shaped, oxidase [+], grows in alkaline media. Endemic to developing countries. Prompt oral rehydration is necessary.

Answer 42

Vibrio cholerae

Question 43

Gram (-) Usually transmitted from pet feces (puppies), contaminated milk, or pork. Causes messengering adenitis that can mimic Crohn disease or pseudoappendicitis. Produces H2S.

Answer 43

Yersenia enterocolitica

Question 44

Causes gastritis and peptic ulcers (especially duodenal). Risk factor for peptic ulcer, gastric adenocarcinoma and lymphoma. Curved G(-) rod that is catalase, oxidase, and urease [+] (can use urea breath test for Dx). Creates alkaline environment. Most common initial treatment is triple therapy: PPI + clarithromycin + either amoxicillin or metronidazole.

Answer 44

Helicobacter pylori

Question 45

Spiral shaped bacteria with axial filaments and include Borrelia, Leptospira, and Treponema.

Answer 45

Spirochetes

Question 46

Found in water contaminated with animal urine. Causes myalgias (classically in calves), flu-like symptoms, jaundice, photophobia with conjunctival suffusion (erythema without exudate). Prevalent among surfers and in tropics (i.e., Hawaii).

Answer 46

Leptospira interrogans or leptospirosis

Question 47

This infection causes severe jaundice and azotemia from liver and kidney dysfunction; fever, hemorrhage, and anemia. Found in water contaminated with animal waste residues. What is it’s clinical agent and aka?

Answer 47

Icterohemorrhagic leptospirosis - aka: Weil’s disease

Question 48

Disease transmitted by Ixodes (also a vector for Babesia). Natural reservoir is the mouse. Mice are important for the tick life cycle, common in NE US. Symptoms: Erythema Chronicum Migrans; flu-like symptoms, +\- facial nerve palsy. Late symptoms: monoarthritis (large joints) and migratory polyarthritis, cardiac AV nodal block, neurologic (encephalopathy, facial nerve palsy, polyneuropathy).

Answer 48

Lyme disease- caused by Borrelia burgdorferi

Question 49

Localized disease presenting with painless chancre. Dark field microscopy can be used to visualize organism in fluid from chancre. Serologic testing VDRL/RPR (non-specific), confirm diagnosis with specific test (e.g. FTA-ABS).

Answer 49

Caused by Treponema pallidum - Primary syphilis.

Question 50

Disseminated disease with constitutional symptoms, maculopapular rash (palms and soles), condylomata lata (also confirmable with dark-field microscopy). Serologic testing VDRL/RPR (non-specific), confirm diagnosis with specific test (e.g. FTA-ABS).

Answer 50

Treponema pallidum- secondary syphilis Secondary syphilis- Systemic. Latent syphilis ([+] serology without symptoms) follows.

Question 51

Gummas (chronic granulomas), aortitis (vasa vasorum destruction), neurosyphilis (tabes dorsalis, "general paresis"), Argyll Robertson pupil. Signs: broad-based ataxia, [+] Romberg, Charcot joint, stroke without hypertension.

Answer 51

Treponema pallidum - Tertiary syphilis For neurosyphilis: test spinal fluid with VDRL or RPR.

Question 52

Saber shins, saddle nose, CN VIII deafness, Hutchinson teeth, mulberry molars. Prevention can be acquired by treating mother early in pregnancy, as placental transmission typically occurs after first trimester.

Answer 52

Congenital syphilis

Question 53

Argyll Robertson pupil: what is it, and what is associated with it?

Answer 53

The pupil constricts with accommodation but is not reactive to light. Associated with tertiary syphilis. AKA- prostitute pupil- accommodates but does not react.

Question 54

What is VDRL?

Answer 54

Test for detection of treponema pallidum. ****may create false positives because it detects nonspecific antibody that reacts with beef cardiolipin. For: Viruses (mono, hepatitis) Drugs Rheumatic fever Lupus and Leprosy

Question 55

What is the Jarisch-Herxheimer reaction?

Answer 55

Flu-like syndrome after antibiotics are started- due to killed bacteria releasing pyrogens.

Question 56

A pleiomorphic, gram-variable rod that is involved in vaginosis. Presents as gray vaginal discharge with a fishy smell; nonpainful (vs. vaginitis). Assoc. with sexual activity, but not sexually transmitted. Clue cells, or vaginal epithelial cells covered with the bacteria, visible under the microscope. What microorganism is this, and what is the treatment?

Answer 56

Gardnerella vaginalis | Tx-Metronidazole or clindamycin

Question 57

Ixodes ticks (vectors are deer and mice). Granulocytes with morulae in cytoplasm.

Answer 57

Anaplasma spp.

Question 58

Cat scratch disease?

Answer 58

Bartonella spp.

Question 59

Organism that causes relapsing fever. Transmission source are louse (recurrent due to variable surface antigens).

Answer 59

Borrelia recurrentis

Question 60

Gram (-) Organism associated with unpasteurized dairy- causes undulant fever.

Answer 60

Brucella spp.

Question 61

Organism that causes Q fever; no arthropod vector: tick feces and cattle placenta release spores that are inhaled as aerosols of cattle/sheep amniotic fluid. Presents as pneumonia. **spore former

Answer 61

Coxiella burnetii

Question 62

Rash is usually rare during infection. Organism is found in Lone star ticks that cause appearance of monocytes with morulae (berry-like inclusions) in cytoplasm.

Answer 62

Ehrlichia chaffeensis

Question 63

Organism associated with ticks, rabbits, and deer fly- causes Tularemia.

Answer 63

Francisella tularensis

Question 64

Gram (-) Organism associated with animal bite, dogs, cats: causes cellulitis, osteomyelitis

Answer 64

Pasteurella multocida

Question 65

This organism produces headache, fever, and a rash that typically starts at wrists and spreads to trunk, palms, and soles. Obligate intracellular organisms that need CoA and NAD+ because they cannot synthesize ATP. Most common in North Carolina.

Answer 65

Rocky Mountain Spotted Fever - Richettsia rickettsii

Question 66

Organism that starts centrally (trunk) and spreads out, sparing palms and soles. One type is endemic to fleas, one to ticks, and one is epidemic in human body louse. What are they??

Answer 66

Typhus: Flea- Richettsia typhi Louse- Richettsia prowazekii Tick- Richettsia rickettsii

Question 67

Obligate intracellular organism (can't make its own ATP), that cause mucosal infections. Two forms: elementary body, and reticulate body. Causes reactive arthritis (Reiter's Syndrome), follicular conjunctivitis, nongonococcal urethritis, and PID. Giemsa stain.

Answer 67

Chlamydia trachomatis

Question 68

Obligate intracellular organism (can't make its own ATP), that cause mucosal infections. Two forms: elementary body, and reticulate body. Both of these strains cause atypical pneumonia, transmitted by aerosol. Giemsa stain.

Answer 68

C. Pneumonia and C. Psittaci

Question 69

Lymphogranuloma venereum- small, painless ulcers on genitals --> swollen, painful inguinal lymph nodes that ulcerate ("buboes"). What is the microorganism, the subtype, and treatment?

Answer 69

Chlamydia trachomatis serotype L1, L2, and L3. Treat with doxycycline.

Question 70

Classic cause of walking pneumonia (insidious onset, headache, nonproductive cough, patchy or diffuse interstitial infiltrate). X-Ray looks worse than patient. High titer of cold agglutinins (IgM), which can agglutinate or lose RBCs. Grown on eaton agar. Penicillin ineffective since the organism has no cell wall.

Answer 70

Mycoplasma pneumoniae

Question 71

What is this organism: bone of child with sepsis, on top of the bone, on the metaphisis of the bone: yellowish area, looks like an abscess - osteomyelitis . In addition, this child has sickle cell.

Answer 71

Salmonella Why is it on metaphisis of bone? BC most of the blood supply is supplied there and the mechanism of spread is hematogenous (comes from another source and then it gets to the bone).

Question 72

What is seen when you have a focal myocardial inflammation with multinucleate giant cells?

Answer 72

Aschoff bodies (rheumatic fever)

Question 73

This microorganism produces a cord factor (serpentine cord) appearance in virulent XXX strains. It activates macrophages (promoting granuloma formation) and induces release of TNF-alpha. Sulfatides (surface glycoproteins) inhibit phagolysosomal fusion. What microorganism is this??

Answer 73

Mycobacteria spp.

Question 74

This infection can be chronic where it can cause blindness (due to follicular conjunctivitis in Africa). What is the microorganism and the subtype?

Answer 74

Chlamydia trachomatis - Types A, B, and C.

Question 75

This infection can cause Urethritis/PID, ectopic pregnancy, neonatal pneumonia, (staccato cough) with eosinophilia, neonatal conjunctivitis (1-2wks after birth). What is the microorganism and the subtype?

Answer 75

Chlamydia trachomatis | Types: D-K