GI tract Pathogens Flashcards

Question

Calciviridae-Norovirus (GI)

Answer 1

* _{^{Star of David virus particles}} * **_{^{Positive ssRNA-NON enveloped icosahedral}}** * _{^{Found in GI tract}} * **_High risk:_** * _{^{Food & water enviromentally stable}} * _{^{Outbreak in large groups (cruise ships)}} * _{^{Virus alters integrity of SI brush border}} * **_Symptoms:_**_{^{Incubation 1-2 days fever}} * _{^{Rapid onset of Vomiting & diarrhea 2-3 days}} * "winter vomiting disease" * **_Diagnosis:_** Clinical signs 1st * **_Treat:_** Self-limiting BUT use oral rehydration * **_Prevention:_** Sanitation * Resistant @ 60C, Low PH, & *detergents/Chlorination* * ***Re-infection*** or infection w/other genotype

Answer 2

* Wheel-like=Rota/__{^{Segmented 11 parts}}_ * _{^{dsDNA, NON-enveloped icosahedral nucleocaspid}} * Stable over a WIDE range of temp/pH * **_High risk:_** Infants/children * Winter-spring months * Causes ***shortening & blunting*** of villi w/Mononuclear cell infiltration * **_Disease:_** ***Gastroenteritis*** * Icubation 1-3 days w/symptoms 3-8 days * ***Clinical triad=***Fever, vomiting, diarrhea _^{_{(coryza/infection of URT & cough)}}_ * ***#1 cause of diarrhea*** in 6-24 months * **_Diagnosis:_** ID in stool * **_Treat:_** _{^{Children w/immunodef=Rotavirus-specific immunoglobulin prep (orally)}} * **_Vaccine-_** * ***Rotarix***-_{^{Human Attenuated-G1&P8 2 doses}} * ***RotaTeq-***_{^{Bovine strain-express human VP4-7 (3) doses}}

Answer 3

* ds DNA, NON-eveloped ***12 protruding fibers (penton)*** from corners of caspid * Found in ***Late fall-winter*** * **_High risk:_** Infants * **_Disease:_** Infantile diarrhea Inoculation 7-8 days w/symptoms 8-12 days * ***Watery diarrhea & fever*** * _Diagnosis:_ *Serotype 40/41* in stool * **_Other serotype_**: * Pharyngoconjunctival fever (pools) * Acute Rep disease (military) * Pneumonia

Answer 4

* Star-like shape for each virus particle * (+) ssRNA non-eveloped * ***#2 cause*** of infantile diarrhea __{^{(#1 rota)}}_ * **_High risk:_** *Institutionalized Elderly* & immunocomprimised children * **_Disease:_** Gastroenteritis __{^{(milder than rota)}}_ * Icubation 3-4 days, symptoms 5+ days * ***Winter Peak*** in temperate climates * NO vaccine

Answer 5

* "**_Daycare Diarrhea"_** * Endemic=homosexual males & children * Dyenteriae _{^{(most severe)}} & Sonnei _{^{(common in USA)}} * Flexneri **_^(poor)** & Boydii **_^(rich)** * Gram (-) rods/Non-motile **_{^{(salmonella is motile)}}** * 4 F's _{^{(finger, food, flies, feces)}} Low dose _{^{(survives acidity)}} * **_Virulence-_** * Invasiveness **_{^{(moving to neighbor cell w/o leaving)}}** * **_{^{Enter through M-cells, Enter macrophages which recruit IL-1 &8, Break out of macro to infect Epi cells @ basal surface, Final POLYMERIZE actin filaments (movement)}}** * Enterotoxins & Shiga-toxin **_^(verotoxin)**

Answer 6

* _**Enterotoxins-***Common in all 4*_ * **ShET1 & 2 _{^{(also found in EAEC)}}**=Blocks absorption of electrolytes, glucose, & amino acids in GI lumen **_{^{(watery diarrhea)}}** * **_Shiga Toxins (AB)_**-*_S.Dysenteriae_* * _{^{Cytotoxin(stx)=Shiga kills GI epi & endo cells}} * _{^{Inhibits protein synthesis inactivating 60S}} * _{^{Synergy w/LPS=Inflammatory cytokines=Damage to endo of BV (bloody diarrhea)}} * **_Bacillary Dysentery_** (watery-Bloody) _{^{incubation 36-72hrs}} * Non-specific symptoms-**fever & cramping** * 48 hrs after **watery diarrhea** * Dysentery (**invasion & damage mucosa)**

Answer 7

* **_HUS-_**Assoc w/Dysenteriae **__{^{(shiga toxin)}}_** * _{^{Causes hemolysis, renal failure (uremia), DIC}} * _{^{Primary disease of infants & children}} * **_Reiter's syndrome_** **__{^{(reactive arhritis)}}_**-Autoimmune * _{^{2-4 weeks after Flexneri (poor) infection}} * _{^{Triad-"Can't see, Can't pee, Can't climb a tree"}} * _{^{Men 20-40 years & HLA-B27 (Spondyloarthropathy)}} * **_Shigellosis=_**Self limiting w/water & electrolyte therapy * **_{^{Antidiarrheal compounds inhibit peristalsis NOT recommended}}** * **_Diagnosis-_**Non/lactose fermenter * Hektoen enteric agar**__{^{(shigella/salmonella)}}_** Faint green color ***NON-H2S producer (differs from Salmonella)***

Answer 8

* Gram(-) rod, non-lactose fermenter * DOES make ***H2S & Motile*** **_{^{(unlike Shigella)}}** * Found in poultry, eggs, dairy products * Need HIGH infective dose=***Acid sensitive*** * **_High risk:_** Children & elderly due low acid * **_Local invasion-_**ingestion, colonization in ileum/cecum, mucosal invasion (M-cells), inflammation, ulcers=***Bloody diarrhea*** * **_Enterotoxins-_**Adenylate cyclase(cAMP), fluid production (large/small)=***Watery diarrhea*** * **_Systemic invasion-_**Multiply in endosome/phagosome * Growth inside macrophage-Goes to lymphatics

Answer 9

* **_Gastroenteritis/Salmonellosis:_** * Incubation time 6-48hrs * Inflammatory diarrhea w/orw/o blood * Lasts 2-7 days self limiting * **Systemic infection** **_{^{(sicklecell pts more susceptible)}}**: * Enter blood through lymph=Septicemia * Brain _{^(meningitis)}, bone **_{^{(osteomyelitis)}}**, lungs **_^(pneumonia)** * **_Treat:_** neonates, elderly, sickle cell w/antibios * **_Diagnose:_** Hektoen enteric agar **_{^(blue-green)}**w/Hydrogen sulfide production _{^{(black center)}}

Answer 10

* _{^{Gram (-) comma or S shaped ROD}} * _{^{Polar flagella motile}} * **Microaerophilic** **_{^{(O2 but lower lvls than atmosphere)}}** _{^{& grows best @ 42C}} * _{^{Zoonotic (cattle, chickens, pets)}} * **_Transmission_**: _{^{Oral-fecal, water-food w/animal feces}} * Poultry, beef, milk-***Food*** * Pets-***Children*** * **_High risk:_** Young children, immunocompromised, decreased/neutral stomach acids **_{^{(antiacids/milk)}}** * _{^{Common cause of diarrhea in US & UK (treat w/antibiotics longer than 1 week)}} * _{^{Diagnose: Campy-BAP or Skirrow (antibiotics-Vancomycin, polymyxin B) selective of other enteric microorganisms, which grows @ 42C}}

Answer 11

* **_Virulence & Pathogenesis:_** * Toxin production-invasion of epicells & survival in monocytes **_{^(salmonella)}** * **_Enterotoxin-_**Electrolyte movement **_{^{(watery diarrhea)}}** * _{^{Followed by inflammatory diarrhea-Invasion of epi=ulcers in bowel mucosa}} * _{^{Watery diarrhea w/foul smelling bloody feces (10+stools/day)}} * _{^{Mimic acute appendicitis (self-limiting)}} * _{^{Systemic infection: survives in monocytes then carried to other parts of body=Septicemia}} * **_Complications-Autoimmune_** * ***Guillain-Barre:*** Acute neuromuscular paralysis * _{^{Cross reactivity w/O Ag & glycosphigolipids (peripheral NS)}} * ***Reactive arthritis:*** inflammation of joints

Answer 12

* _{^{Gram(-) rod NON-lactose fermenters}} * _{^{Grows @ 25C}} **_{^{(cold enrichment)}}** _{^{& motile BUT not @ 37C}} * _{^{Found in GI of animals}} * _{^{Contaminated food, Pet feces, High dose needed}} * **_High Risk:_** Any one in cold climate (North) * **_Virulence/Pathogenesis:_** Enterotoxin & invasion of mucosa-Inflammation=Ulceration * Systemic to mesenteric lymph=**_Mesenteric adentitis_** * _{^{SEVERE ab pain in LRQ pseudo-appendicits}} * **Complication**=_Reiter's syndrome_ **_{^{(HLA-B27-Same as shigella)}}** * **_Diagnose_**: Stool culture "cold enrichment" 2-4 weeks Yersinia INCREASE and other microbes DIE

Answer 13

* Gram + rod & anaerobic spore former * Found in GI tract-High % colonies in Hospital pts * **_Transmission:_** * **_{^{Endogenous or via spores}}** * **_{^{Fecal-oral (clothing, surfaces)}}** * **_High Risk:_** **_^Hospital** * Long term Antibiotic use **__{^{(ampicillin, cephalosporins, clindamycin)}}_** * _{^{Hospital pts-Long term stay (4weeks)}} * **_Anibiotic Assoc Diarrhea-_**_{^{Mild diarrhea to pseudomembranous colitis}} __{^{(4-10 days after antibio & 2weeks after termination)}}_ * **_{^{Most common nosocomial diarrhea (hospital)}}**

Answer 14

* Adhesion (surface layer proteins) * **_Toxin A (enterotoxin_**)_{^{=Hypersecretion of fluid, induce inflammation (cytokine production & Hemorrhagic necrosis)}} * **_Toxin B (cytotoxin)_**_{^{=Depolymerization of actin, loss of cytoskeleton & cell death}} * **_Toxin C (Super BUG)_**_{^{=Deletion of A/B reg gene tcdC-Makes 20x more (resistant to antibios)}} * **_Pseudomembranous colitis-_** Severe ab pain, watery diarrhea w/high # of neutrophils in stool * _{^{Irreg yellow plaques nectotic debris (fibrin&mucus)}} * **_Diagnose:_** _{^{Toxin detection in stool or ELISA for A/B}} * **_Treat:_** _{^{Stop current antibio & use Metronidazole/Vancomycin}} * **Restore normal GI flora**=_{^{Saccharomyces boulardii or fecal transplant}}

Answer 15

* Typhi & Parathyi * Gram(-) rod/motile, non-lactose, produces H2S * ***Found in gallbladder*** up to 1 year * **_High risk:_** Poor hygiene & traverlers to endemic areas under 30 yrs old * **_Virulence:_** Multiplies in macrophages w/LPS * **_1st week_**=_{^{Fever w/bradycardia (no GI)}} * **_2nd week_**=_{^{GI w/rash on trunk/ab (Rose spots)}} * **_3rd week_**=_{^{hepatosplenomegaly w/GI bleeding (erosion to peyer's patches)}} * _{^{Complications=shock, stupor, seizures, psychosis, myelitis, and pneumonia.}}

Answer 16

* W/GI perforation=***Fatty degeneration*** * _{^{Accum of fat in cells w/enlarged spleen, liver, mesenteric glands, kidney, & heart}} * **_DIC-_**Thrombophlebitis __{^{(vein inflammation=Blood clot)}}_ * **_Diagnose: _** * Specimen-Blood, bone, urine, stool w/chornic pt * Culture=***Hektoen*** __{^{(non-lactose fermenter)}}_ * Serology=***Widal test*** _{^{(test tube agglutination)-Detect Ab against O/H Ag}} * **_Treat:_** Borad spec fluroquinolones, cipro, ceftriaxone * **_Prevention:_** ID & treat carriers __{^{(removal of gallbaldder)}}_ * **_Vaccine:_** Capsular=**VI** & live attenuated=**Ty21a** * _{^{Both taken oral for traverler's in endemic areas}}

GI tract Pathogens Flashcards

(40 cards)