exam 3

Question 1

pathogens with animals as reservoirs

Answer 1

Yersinia, most salmonella

Question 2

pathogens with humans as reservoirs

Answer 2

Shigella, Salmonella typhi

Question 3

opportunistic pathogens

Answer 3

Escherichia, Klebsiella, Proteus

Question 4

pathogens spread endogenously

Answer 4

E.coli

Question 5

true pathogens

Answer 5

always associated with disease. Salmonella, shigella, yersinia

Question 6

serologic group of EB based on 3 groups of antigens

Answer 6

1) Somaic O polysaccharides (LPS) - common to all EB, specific to each genus
2) K antigens (capsule) - common but different among both EB and non-EB
3) H proteins (flagella) - heat-liable, can undergo antigenic variation

Question 7

LPS consists of three parts

Answer 7

heat-stable major cell wall antigen

1) Lipid A - fatty acids attach LPS to OM
2) Core polysaccharides - joined to lipid A, 10 sugars
2) O side chain (Oantigen) - polyssachiride chain varying in composition

Question 8

General EB virulence factors

Answer 8

Endotoxin - lipid A of LPS released upon cell lysis
Can cause 5 things:
1-hypoglycemia
2-fever
3-reduced fever (soluble portion)
4-shock
5-DIC thrombosis (dissem interv clotting) - clotts but blood still pumping -> bleed out

Capsule - antigens prevent binding of antibodies to bacteria, poor immunogens

Antigenic phase Variation - capsular K and flagella H antigens under genetic control, protects from antibody-mediated cell death

Type III secretion system - delivers virulence factors directly into eukaryotic cells

Iron - is most important growth factor for EB

Hemolusins - lyse host cells->release iron bound in heme proteins (hemoglobin, myoglobin)

Enterobactin, aerobactin - act as competitive iron chelating compounds (lactoferrin, transferring)

Question 9

E.coli virulence factors

Answer 9

Adhesins - clonization fator antigen (CFA/I-CFA/III)
AAF/I, AAF/III, Bfp, Ipa

Exotoxins - shiga toxins lysogenic strains only,

Question 10

E.coli epidemiology

Answer 10

most common G- bacilli isolated from patients with sepsis, causes more than 80% of all UTis, prominent cause of gastroentericsin developing countries, most infections are endogenous(when immunocompromised)
Exceptions: neonatal meningitis, gastroenteritis

Question 11

Septicemia

Answer 11

Originates from urinary or GI tract infections. mortality rate is 90% when immunocompromised, when primary infection is in the abdomen or CNS

Question 12

Urinary tract infection

Answer 12

ascending infection, originate in colon->urethra->bladder->kidney or prostate, strains producingP pilli, AAFs, and Dr are the most virulent UTI strains:bind very tight to bladder and upper urinary tract - prevent elimination. Hemolysin A - lyses cells , stimulates inflammatory response.

Question 13

Neonatal meningitis

Answer 13

CNS infections in infants less than 1 month old, primary cause by E.coli and group B streptococci,
E.coli K-1 (K1 capsular antigen) - common in G tract of pregnant women and newborns, unknown ho causes disease in infants.

Question 14

6 groups cause gastroenteritis

Answer 14

• Enterotoxigenic (ETEC)
• Enteropathogenic (EPEC)
• Enterinvasive (EIEC)
• Enterhemmorhagic (EHEC)
• Enteroaggregative (EAEC)
• Diffusely adherent (DAEC)

Question 15

ETEC

Answer 15

Enterotoxigenic E.coli - most common in developng countries, high infectious dose no perso to person spread

Question 16

Guillain Barre Syndrome

pathogens

Answer 16

Campylobacter jejuni, Campilobacter upsaliensis

autoimmune disorder of peripheral nervous system, due to closs reactivity between oligosaccharides of campylobacter and lipids on surface of neural tissue?

Question 17

Helicobacter pylori

colonization
tissue damage
evidence

Answer 17

Initial colonization:
blockage of acid production by bacterial acid-inhibitory protein. Neutralize gastric acid by ammonia, produced by urease activity

Tissue damage:
Urease byproducts-mucinase, phospholipase
Vacuolating cytotoxin - induces inflammatory response

Evidence tha H.pylori is the tiologic agent in all cases of type B gastroenteritis (ulcers)

1) a 100% association between gastritis and infection with organism
2) production of experimental infection in both animals and humans
3) histologic resolution of pathologic changes when specific therapy used to eradicate the organism

Question 18

Proteus mirabilis and what causes stones

Answer 18

most common disease produced by this genus is UTI

Produces urease->splits urea into carbon dioxide and ammonia->increases urine pH->facilitates formation of renal/bladder stones and is toxic to uroepithelium

Question 19

Septicemia

Answer 19

E.coli
Originates in GI and urinary tract,
90% mortal if initial infection is in abdomen or CNS

Question 20

UTI

Answer 20

E.coli
Ascending infection, originate in colon
Strains producing P pilli, AAFs and Dr are the most virulent, bind very tightly to bladder and upper urinary tract, hemolysin A lyses cells stimulates inflammatory response

Question 21

Neonatal meningitis

Answer 21

E.coli, group B strep
CNS infections in infants <1 y.o.
E.coli K1 (K1 capsular antigen) - common in GI tract in pregnant women and newborns

Question 22

Salmonella

Answer 22

Resistant to acid environments (stomach, phagosome) - acid tolerance response gene
can colonize all animals,some do not host disease in nonhuman hosts
From contaminatexd food and fecal-oral transmission - children (fecal-oral), Adults (contaminated food)
Poultry, eggs, fecal oral
Multiply innside

Question 23

Enteritis

Answer 23

most common form of salmonelosis, from contaminated food/water, 6-48 hrs first symptoms, resolve in 2-7 days, diarrhea no blood
Salmonella

Question 24

Septicemia

Answer 24

risk is higher in immunocompromised,
osteomylytis, endocarditis and arthritis
Salmonella

Question 25

Enteric fever

Answer 25

``` Typhoid - S.typhi Paratyphoid fever - S.paratyphi 7 day fever followed by GI symptoms after colonization of gall bladder Salmonella ```

Question 26

Shigella

Answer 26

70% in childen <15 Endemic in homosexuals Epidemic in daycares and nurseries Transmitted by fecal oral route (contaminated hands) Multiplies inside, replicate in phagosome unlike salmonella move from cell to cell like lysteria Shiga toxin

Question 27

Shigellosis

Answer 27

initial(enterotoxin) - cramps, fever, watery diarrhea Secondary (cell destruction) - lower abdominal cramps, diarrhea with blood, pus and mucus self limiting, but antibiotics used to decrease spread to family members

Question 28

Yersinia

Answer 28

All are zoonotic humans are the accidental host, fleas and the vector Y.pestis - systemic disease, high mortality Y.enterocolitica - enteric, rarely systemic Urban plague - rats are reservoir Sylvatic plague - wildlife are reservoirs impossible to eliminate

Question 29

Bulbonic plague

Answer 29

Y.pestis must be bitten by infected flea, high fever painful bubos (inflamated lymph nodes) in groin, 75% mortality rate, bacteremia rarely develops even with treatment

Question 30

Pneumonic plague

Answer 30

Y.pestis initially fever, malaise, pulmonary signs develop within 1 day, patients are highly infectious - aerosol transmission, 90% mortality rate even when treated

Question 31

Enterocolitis

Answer 31

Y.enterocolitica ingest contaminated food and water; diarrhea fever, abdominal pain for 2 weeks, can becaome chronic and persist for 2 months

Question 32

Bacteremia

Answer 32

Y.enterocolitica Blood transfusions - related bacteremia yersinia can grow at 4C

Question 33

Klebsiella

Answer 33

K.pneumoniae, community-acquired pneumonia, necrosis of alveolar spaces, cavity formation blood tinged sputum, also causes wound, soft tissue infections and UTIs

Question 34

Proteus

Answer 34

P.mirabilis UTI - most common !!! Produces urease-splits urea into carbon dioxide and ammonia - increases urine pH - facilitates formation of renal/bladder stones and is toxic to uroepithelium

Question 35

EB treatment and prevention

Answer 35

Antibiotics cannot be used for E.coli and Salmonella gastroenteritis due to increased risk of secondary inf. and prolonged fecal carriage Cannot prevent endogenous infections due to most organism being normal microbiota Can prevent exogenous - - Salmonella - proper preparation and storage of poultry products - Shigella - proper hygene, especially in children Y.pestis - vaccines

Question 36

Vibrio cholerae

Answer 36

serotypes based on O antigen (LPS) V.cholerae O1 and O139 cause classic epidemic and pandemic cholerae, other cause cholera but not epidemic/pandemic grow naturally in water enviroments worldwide (increased salinity low temperatures, high numbers in water with shellfish asymptomatically infected humans serve as reservoir initially sporadic and endemic disease spread during war Spread by contaminated food and water, requires high infectious dose with normal gastric acidity pH 2.0-2.5 Gastric acidity decreases, ID decreases signs begin 2-3 days after ingestion. increased flui loss, colorless odorless feces, no protein, mucus - rice water stools death in 60% of untreated

Question 37

Vibrio parahaemolyticus

Answer 37

Consumption of improperly cooked oysters, Self limiting diarrhea to mild cholera-like illness develops 24 hrs after consumption - explosive watery diarrhea no blood or mucus, most recover in 72 hrs can cause wound infections in people exposed to contaminated seawater

Question 38

Vibrio vulfinicus

Answer 38

Rapidly progressive wound infections after exposure to contaminated seawater initiall swelling, pain; development of vesicles; tissue necrosis, systemic signs fever and chills 50% mortality rate once systemic even with treatment

Question 39

Aeromonas

Answer 39

Ubiquitous in water, GI carriage in 30% increases during warmer months - Opportunistic systemic disease - in immunocompromised - Diarrheal disease - in immunocompetent, acute and severe in children resembling shigelosis

Question 40

Plesiomonas shigelloides

Answer 40

Taxonomically related to Proteus, serologically to Shigella Infected from contact with contaminated water, seafood or exposure to amphibians or reptiles Self limited gastroenteritis with 48hrs onset susceptibility is a must

Question 41

Pseudomonas

Answer 41

Ubiquitous in water, soil, vegetation Found throughout hospital (food, cut flowers, sinks, toilets Normal microbiota in hospitalized and immunocompromised, opportunistic infections. P. aerogenosa most common

Question 42

Pseuomonas pulmonary infections

Answer 42

lower respiratory tract colonization in 100% patients with cystic fibrosis and chronic lung disease

Question 43

pseudomonas primary skin infections (burns)

Answer 43

predisposing factors for infection, moist surface of the burn, lack of immune response to invasion, topical ab has little success

Question 44

Pseudomonas primary skin infections (folliculitis)

Answer 44

results from immersion in contaminated water, hot tubs, swimming pools, secondary folliculitis infections in people with bad acne

Question 45

Pseudomonas UTI and ear infections

Answer 45

UTI - primarily in patients with long term indwelling urinary catheters treated with range of AB Ear infections - Otitis extrna media - swimmers ear malignant external otitis - in diabetics, elderly - damage cranial nerves and bone, surgery required

Question 46

Pseudomonas eye infections

Answer 46

occur after truma to cornea then exposure to organism in contaminated water - contact lense abraison, scratch - corneal ulcers, eye-threatening disease

Question 47

Campylobacter jejuni

Answer 47

most common cause of bacterial gastroenteritis in US

Question 48

Campylobacter coli

Answer 48

2-5% of campylobacter associated gastroenteritis

Question 49

Campylobacter fetus

Answer 49

systemic infections - bacteremia, arthritis, meningitis