enteric bac 3

Question 1

Vibrio Cholerae Bacteriology

Answer 1

Gram NEGATIVE rod: Curved comma-shaped, motile(can be seen on darkfield microscopy of stool), Aerobic + , Facultatively anaerobic. (Reservoirs: humans and plankton ecosystem of Indian ocean), oxidase +, halophile, gives acid rxn on triple-sugar-iron agar

Question 2

What are pathogenic strains of V. Cholerae?

Answer 2

O cell wall antigens: O1 Biotypes (El Tor and cholera), O1 Serotoypes (Ogawa, Inaba- endemic to Gulf of Mexico-, Hikojima). O1 snf O139 causes epidemic disease and indicate infection by bacteriophage

Question 3

V. Cholerae Transmission

Answer 3

Fecal-Oral (shed by asymptomatic carriers in incubation or convalescencce), untreated water or undercooked shellfish

Question 4

V. Cholerae Infectious Dose is High or Low?

Answer 4

High (1000-1000000 Ius) b/c it’s not adapted to a human pathogen but it’s pathogenecity in humans is only enabled by bacteriophage (Note: c. cholerae is normally killed by stomach acid)

Question 5

V. Cholerae Virulence

Answer 5

Mucinase (clears path to brush border), Toxin Coregulated Pilus-TCP- (attach to brush border) , Choleragen: Cholera toxin (an enterotxin) which is carried by lysogenic bacteriophage CTX

Question 6

What is the Pathogenesis of Cholera Toxin?

Answer 6

It has A-B subunit structure . It causes persistent activation of ADENYLATE CYCLASE which causes cell to release water and electrolytes. It blocks absorption from microvilli, promotes secretion from crypt causing MASSIVE DIARRHEA (Rice Water Stool) which can lead to morbidity and death. The B binds the ganglioside receptor GM1 on intestinal lining.

Question 7

What are some clinical findings expected with V. cholerae infection?

Answer 7

Vomiting, (NO FEVER- except in infancy), Acidosis and Hypokalemia- when acidemia is corrected-, Dehydration (leading to cardiac and renal failure) with prolonged skin tenting, If severe, glassy/sunken eyes may be present, sunken fontanelle in an infant, weak pulse, Hypoglycemia (convulsions may accompany in a peds. pt)

Question 8

What is the treatment for V. Cholerae?

Answer 8

Disease is self-limiting therefore Rehydration: IV Lactated Ringer solution for up to 4 hrs., Check for return of urine output every 3-4 hrs after 6-8 hrs of rehydration. To reduce shedding, you can use a short course of Tetracycline (prophylaxis protection from close contacts), doxycycline, furazolidone, or ciprofloxacin

Question 9

V. Parahaemo bacteriology

Answer 9

Oxidase +, Gram NEGATIVE rod: Curved motile, salt water-born halophile (Mexico)

Question 10

What disease is often caused by v. parahaemolyticus? Symptoms?

Answer 10

Disease: Gastroenteritis Symptoms: N/V/D/ab cramps/Fever

Question 11

V. parahaemolyticus virulence

Answer 11

Eterotoxin and Hemolysin

Question 12

V. parahaemolyticus diagnostic tests include:

Answer 12

Culture in *% NaCl, Culture from stool on THIOSULFATE-CITRATE-BILE SALTS-SUCROSE media, Bloodwork for DIC, HBV, HCV, Fe, Stool smear (blood, luekocytes, bacteria, parasites0eggs/ova)

Question 13

A HPI of a V. parahaemolyticus infected patient may reveal:

Answer 13

undercooked seafood(esp. shellfish), In a patient with complications of infection Immunodeficiency, Liver Disease, Fe Overload, Kidney Disease, Sepsis predospisition

Question 14

What is treatment for V. parahaemolyticus?

Answer 14

Oral Rehydration (It is a self-limited disease). If complicating factors or cyclic high fever is present, use doxycycline or quinolone , IV rehydration

Question 15

V. vulnificus Bacteriology

Answer 15

Oxidase +, Gram NEGATIVE rod: Curved motile, some encapsulated, salt water-born halophile (Gulf Coast)

Question 16

Where are V. vulnificus bacteriology often concentrated?

Answer 16

Filter- feeding mollusks

Question 17

V. vulnificus virulence

Answer 17

Hemolysin and Protease Exotoxins, Produes Siderophores (infection is exacerbated with Fe overload)

Question 18

What disease is often caused by v. vulnificus Symptoms?

Answer 18

Cellulitis progressing to necrotizing fasciitis; Fatal septicemia in immunocompromised individuals; Septicemia Symptoms: Hemorrhagic bullae, high fever, chills, severe pain progressing to numbness (feet)

Question 19

A HPI of a V. vulnificus infected patient may reveal:

Answer 19

A shellfish market worker who had a wound or a person whose whound was exposed to sea water as in alligator bite or fish hook puncture; Predisposing conditions (Immunodeficiency, Liver Disease , Iron overload, Kidney Disease)

Question 20

What may be found on a CXR and Radiography of a pat. Infected with V. vulnificus?

Answer 20

ARDS, wound site with shells, fish hooks etc (Respectively)

Question 21

V. vulnificus diagnostic tests include:

Answer 21

Bloodwork (DIC, HBV, HCV, Fe), Gram stain and culture (of aspirate) , Biopsy (reveal gram - bacilli, acute inflammation, tissue necrosis, fat infraction)

Question 22

What is treatment for V. vulnificus

Answer 22

Ceftazidime + Doxycycline OR Antipsuedomonal penicllin ; Alternatives: Cefotaxime or flurouinolones,; Debridement; Treatment of complications (septic shock, DIC, ARDS, RF)

Question 23

Campylobacter Bacteriology

Answer 23

Oxidase + , Catalase +, Gram NEGATIVE rod: Comma/S shaped, MICROAEROPHLIC, motile (flagella), nonspore forming

Question 24

Campylobacter Reservoirs and Transmission

Answer 24

Guts of domestic animals= reservoir, Transmitted: fecal-oral, sexual contact, sick pets

Question 25

Is Infectious Dose of Campylobacter high or low?

Answer 25

high(~10,000 but not as high as vibrio) b/c it’s sensitive to stomach acid

Question 26

Campulobacter Virulence

Answer 26

some strains produce enterotoxin (similar to cholera). Some strains have (S-layer) capsules and can resist phagocytosis from macrophages. (Others: T4SSS, Cytotoxin?)

Question 27

What disease is often caused by Campylobacter? Symptoms?

Answer 27

Mainly Diarrhea (bloody with crypt abscesses and ulcerations or watery). Sepsis (neonates and immunosuppressed)C. jejuni infection predisposes patients to Guillain-Barre Syndrome, Reactive Arthritis, HUS (rare- seen in bloody diarrhea strains). Bacteremia cnan lead to meningitis, vascular infection, abscess

Question 28

Who is vulnerable to Campylobacter infection?

Answer 28

men who have sex with men, complications if HIV+

Question 29

Campylobacter diagnostic tests include:

Answer 29

Sigmoidoscopy( mucosal edema, hyperemia, patchy petechiae, ulceration, r/u toxic megacolon, stool sample culture, Fecal smear (darting motility, leukocytes, erythrocytes, gram stain ), stool PCR tests, Blood culture (if suspect bacteremia), blood agar plates w/ antibiotics, 2 Temperatures, 5%O2/10%CO2

Question 30

What is treatment for Campylobacter?

Answer 30

Gastroenteritis is self -limited (Rehydrate), Use Azithromycin (non-pregnant adults) or Erythromycin (pregnant women /children) if : patient is a child (, has high fever, bloody diarrhea, >8 stools/day, ill >1week, pregnancy, HIV. Treat meningitis with Meropenem, Ampicillin, Chloramphenicol. DO NOT treat diarrhea with antimotility agents.

Question 31

H. Pylori Bacteriology

Answer 31

Gram NEGATIVE rods (LPS) and UREASE (+)

Question 32

What disease is often caused by H. Pylori? Symptoms?

Answer 32

Peptic Ulcer Disese. It is also associated with MALT lymphomas, Gastric Lymphoma, Adenocarcinoma of the stomach (predisposition is the irritation)

Question 33

How is H. pylori transmitted/

Answer 33

Unknown- perosn oto person?

Question 34

H. Pylori Virulence

Answer 34

Flagella is an attachment factor , Urease (breaks down uerea into ammonia , Upregulates Caspases (causing apotposis in neighboring cells), Some strains produce Vac-A Vavuolating cytotoxin, Some produce Cag-A (chemotatic for neutrophils)

Question 35

What is treatment for H. pylori?

Answer 35

Reducre irritation with bismuth salts (Pepto Bismol), PPIs (lansoprazole, omeprazole) may relieve pain and facilatate healing of ulcer, TRIPLE THERAPY includes 1 of the above with 2 antibiotics ( amoxicillin/clarithromcin with PPI or metronidazole/tetracycline with Bismuth subsalicyclate)

Question 36

What are common side effects of Triple Therapy?

Answer 36

Nausea and Metallic Taste