Enterobacteriacea

Question 1

Enterobacteriaceae: gram + or -?
shape?
where does it normally live? where does it colonize?
What medium does it grow on? aerobic or anaerobic?

Answer 1

gram- rods
normally lives in GI tract, but colonizes resp tract of hospital patients
grows on simple medium, in aerobic or anaerobic conditions

Question 2

enterobacteriaceae main virulence factor?

Answer 2

LPS (causes fever, diarrhea, and septic shock via lipid A)

Question 3

4 biochemical characteristics of all enterobacteriaceae?

Answer 3

Facultative anaerobe (can live in aerobic+anaerobic conditions)
Ferment glucose
Oxidase neg
Reduce nitrate to nitrite

Question 4

E. coli diseases?

Answer 4

sepsis
UTIs
meningitis (#1 cause of meningitis in neonates)
wound infection
pneumonia in hospitalized patients
gastroenteritis

Question 5

5 E. coli species that cause gastroenteritis and diarrhea?

Answer 5

ETEC (secretory diarrhea/travelers diarrhea-profuse watery diarrhea)
EPEC (cause lesions in epithelial cells, infantile diarrhea, not bloody)
EIEC (same as shigella, blood, mucus, and lymphocytes in stool, have fever)
EHEC/STEC (create shiva toxin, bloody diarrhea without WBCs and fever, can profess to HUC)
EAggEC (adhere to epithelial cells, watery diarrhea with blood and mucus)

Question 6

Shiga toxin producing E. coli (STEC/EHEC): most common strain? resevoir?

Answer 6

Strain: E coli 0157
Resevoir: Healthy dairy cattle, also sheep, deer, other ruminants

Question 7

E coli 0157 transmission?

Answer 7

Food, person-to-person contact, contaminated water

Question 8

Hemorrhagic colitis symptoms?

Answer 8

abdominal cramps, watery diarrhea, bloody discharge

no fever or WBCs in stool

Question 9

HUS triad of symptoms?

Answer 9

acute renal failure
thrombocytopenia (loss of platelets, increased bleeding)
Hemolytic anemia

Question 10

STEC/EHEC MOA?

Answer 10

MOA: inhibition of protein synthesis in commensals and host cells, damage to microcirculation (infarction of mucosa leads to bleeding into bowel and bloody diarrhea), cause cell apop and cytokine secretion

Question 11

STEC/EHEC clinical diagnosis?

Answer 11

Clinical: Causes bloody and nonbloody diarrhea (first nonbloody w/some ab pain, then bloody w/severe ab pain), hemorrhagic colitis, HUS

Question 12

STEC/EHEC lab diagnosis?

Answer 12

Lab diagnosis: needs to be collected early and before antibiotics are started, test for antigens via multiplex PCR to detect 0157. stain shows no platelets and fragmented RBCs (shistocytes=sign of hemolytic anemia)

Question 13

STEC/EHEC Treatment?

Answer 13

Treatment: Treat the symptoms (If HUS-dialysis and ventilation needed). So hydrate and monitor kidney functions. DONT GIVE ANTIBIOTICS OR ANTIMOTILITY AGENTS (like pepto) (killing the Ecoli causes release of toxins which cause the increase of one another and cause major problems like HUS).

Question 14

Shigella Transmission?

Answer 14

person to person via fecal oral route
water and 5 f’s: food flies fingers fomites feces
Low inoculum needed to spread disease so easily spread

Question 15

Shigella disease and clinical manifestation?

Answer 15

Bacillary Dysentery: abdominal cramps, tenesmus (having to poop but nothing there), pus/WBCs and blood in stool.

Question 16

Edwardsiella diseases?

Answer 16

Causes gastroenteritis (watery diarrhea or bloody diarrhea w/fever, nausea vomiting)
rarely septicemia

Question 17

Salmonella Transmission?

Answer 17

Improper food handling (found in livestock, mainly poultry)
secondary person to person transmission (Typhoid)
takes a lot of the bacteria to cause symptoms

Question 18

5 Salmonella diseases/clinical manifestations?

Answer 18

1. Asymptomatic Carrier
2. Febrile gastroenteritis: malaise, nausea, vomiting(sometimes), abdominal pain, diarrhea
3. Enteric Fever (Typhoid Fever): 2 weeks of bacteremia (fever) and then 2 weeks of cramps and diarrhea
4. Septicemia: bacteremia that can spread throughout body
5. Focal infections: osteomyelitis, meningitis

Question 19

Clinical manifestation of salmonella enteric fever?

Answer 19

fever, headache, constipation, rose spots (purpuric lesions)

Fever has temp-pulse dissociation (relative bradycardia for the temperature)

Question 20

Salmonella: lactose fermentor?

What does it uniquely produce?

Answer 20

Non-lactose fermentor

produces hydrogen sulfide (black)

Question 21

Citrobacter: 2 species and their diseases?

Answer 21

C. freundii- (rarely) cause diarrhea
C. Koseri- (rarely) cause meningitis and brain abscess in neonates
one of the 3 things that cause neonatal meningitis

Question 22

Klebsiella diseases?

Answer 22

pneumonia, atrophic rhinitis

Question 23

Enterobacter diseases?

Answer 23

colonize hospitaly patients causing respiratory tract infections, UTIs, infect wounds
Have antibiotic resistance in their chromosomes

Question 24

Serratia: color when plated?

diseases?

Answer 24

Colonies are naturally red

Nosocomial infections: pneumonia, septicemia, UTI, surgical wound infection, endocarditis, osteomyelitis

Question 25

Proteus: unique plate characteristics?

diseases?

Answer 25

***Only one that swarms (grows in intervals, look like the effect of waves on sand), strongly urease positive***
2nd most common in hospital lab
Renal stones (splits urea leading to bicarb which increases pH of urine causing struvite formation), also causes UTI

Question 26

Yersinia enterocolitica: shape of colonies?
glucose fermentor?
grows at what temp?

Answer 26

pinpoint colonies
glucose fermentor
grows at 25C (lower than most bacteria, likes cooler temps because it has evolved in colder environments (lakes and reservoirs))

Question 27

Yersinia enterocolitica reservoir?

How is it spread to humans?

Answer 27

Pigs are reservoir
Spread through prep of chitterlings (pig intestine)
also spread through blood donations (it can persist and be in blood donation, then blood is stored in fridge and Y enterocolitica can grow at low temp and then upon blood transfusion it is spread to new patient)

Question 28

Y enterocolitica clinical manifestation?

Answer 28

diarrhea
casues terminal ileitis, lymphadenitis, and enterocolitis (diarrhea, abdominal pain, fever)
can persist and then be passed on through blood donation