Bacterial Inf of GI Tract Flashcards
Improperly canned non-acidic food - what problem?
botulism - Clostridium
Botulism
- when onset?
- some effects on the body and its progression?
- how is fever
- 12 to 36 hours after eating improperly canned non-acidic food
- dizziness, dry mouth, blurred or double vision - eye muscle weakness
- abdominal pain, nausea, vomiting, and diarrhea or constipation
- progressive paralysis: all voluntary muscles
- no fever! == there is no bacterial infection!!
Most common cause of death with botulism?
-respiratory paralysis
Where is clostridium found?
endospores in the soil!
Clostridium
1) organism details:
2) where is it found in environment?
3) which toxins and which most common in humans
4) toxin production/activation?
1) Gram+; strict anaerobe; spore forming; rod
2) endospores found in soil - RESISTANT TO BOILING
3) A, B, C1, D, E, F, and G
4) toxin formed as inactive state and activated by proteolytic cleavage upon lysis
spores located at the end of the cells - organism is?
clostridium - botulinum
Botulinal toxin - type of toxin, what it does?
- A-B bacterial toxin
- B portion for binding to receptors on motor nerve endings
- A-portion enters nerve cell and blocks discharge of acetylcholine = FLACCID PARALYSIS
Which organism causes a flaccid paralysis?
the botulinum toxin from clostridium causes this
Which organism causes a rigid paralysis?
Clostridium tetani TOXIN!
What does clostridium botulinum do to infants?
- invades the intestines = constipation followed by generalized paralysis ==> FLOPPY BABY SYNDROME
- Babies get this bc they lack full acidity of stomach and complete gut biome.
- toxin and organism found in feces - low levels in blood
What organism causes floppy baby syndrome?
Clostridium botulinum TOXIN!!!!
Treatment of botulinum poisoning:
- IV antitoxin - horse derived (15% get serum sickness)
- neutralization of circulating toxin
- takes weeks and months to regain full function
Clostridium difficile
- organism details
- causes what disease?
-gram pos, strict anaerobe, spore forming, rod-shaped
- causes antibiotic associated pseudomembranous colitis
- most common cause of nosocomial diarrhea
- rarely invades GI epithelium
Clostridium difficile
- found where in environment?
- transmission?
- found in GI tract of 3% of peoplel and tends to be found more often in hospital GI tracts
- fecal oral transmission - usually hands of hospital personnel are intermediate
most common causes of clostridium difficile infection?
pseudomembraneous colitis - Antibiotic associated- most often caused by 2nd and 3rd gen cephalosporins
Most common cause of nosocomial diarrhea?
Clostridium difficile
**Two things needed to get clostridium difficile infection?
- need to get the organism - in hospital or where ever
- need to disrupt the normal GI flora - aka with antibiotics; diet; stress; chemo
Appearance of pseudomembranes on colon mucosa?
white-yellow plaques
Stool finding - clostridium difficile?
non-bloody
neutrophils in half of patients
Clostridium difficile- patient presentation?
- fever
- abd cramping
- toxic megacolon
- toxin will be found in the stool
Clostridium difficile treatment?
- antibiotic should be withdrawn
- give metronidazole (prefered) or vancomycin (prevent creation of vanco resistant enterococci)
- replace fluids
most often treatment does not get rid of carrier state =occurrence
Shigella -
1) causes what disease?
2) disease occurs where?
1) shigellosis
2) worldwide and especially where no sanitary practices
Shigella -
organism details?
-invades where?
- gram neg; rod; non-lactose fermenting (colorless on MacConkey agar)
- invades distal ileum and colon - rarely penetrate mucosa or enter blood stream
What organism confused with shigella? why?
Salmonella - also non-lactose fermenting
Distinguishing Shigella from Salmonella?
Shigella are different bc:
- not motile
- do not produce H2S
- no gas production from glucose f ermentation
Shigella - virulence factors?
o-antigens (polysaccharide, LPS)
Infectious dose for Shigella vs salmonella?
- shigella = LOW DOSE (EFFECTIVE GI PATHOGEN)
- salmonella = high dose
Shigellosis - presentation in patient?
- 1-4 days incubation
- fever, cramps, wattery diarrhea that later contains blood and mucous
Most likely person to get Shigella or a dysentery infection?
someone who travels abroad
Shigella treatment:
- fluid and electrolyes
- no antibiotics for mild cases
- if severe = give fluoroquinolone (ciproflaxin)
- if peds patient=give Trimethoprim-sulfamethoxazole or azithromycin
Do not give what kind of drugs to shigellosis patient?
antiperistaltic drugs = prolongs fever, diarrhea and excretion of organism
All fluoroquinolones increase risk for?
-tendinitis and tendon rupture
Salmonella -
- causes what diseases?
- enterocolitis
- enteric fevers (typhoid)
- septicemia with metastatic incfections such as osteomyelitis
Salmonella- organism details?
- gram neg rod
- non lactosee fermenting
- H2S production
Salmonella- virulence factors:
- Cell wall o antigen (LPS)
- flagellar H and capsular Vi
All gram negatives have what virulence factor?
LPS! - o-antigen
Salmonella typhimurium- causes what and invasion:
ENTEROCOLITIS-invades epithelial and subepithelial tissue of small and large intestines
- penetrate lamina propria = inflammation & diarrhea - PMNs help prevent spread to adjacent LN but septicemia is possible
- LARGE INFECTIVE DOSE NEEDED
Important host defense against salmonella?
gastric acid!!!
Salmonella Typhi- causes what and invasion?
- typhoid - enteric fever
- small intestine first affected but few GI symptoms
- multiply on mononuclear phagocytes of Peyers patches
- spread to liver gallbladder (carrier state), and spleen = bacteremia - FEVER and LPS induces symptoms
How does salmonella typhi multiply and spread through body?
multiplies and spreads inside/via phagocytes
Salmonella typhimurium - clinical presentation:
-incubation 12-48 hours
-ENTEROCOLITIS begins with nausea and vomiting
then abd pain and diarrhea (with or without BLOOD)
-if blood you need to intervene
-last several days and self limited
Who is at greatest risk for severe Salmonella typhimurium infection?
Enterocolitis severe/like threatening in the very young and very old
Salmonella typhi - clinical presentation:
-onset much slower that typhimurium
-flu like symptoms first
-sometimes constipation
-YES fever
- ROSE SPOTS
if bacteremia becomes high=
-high fever delirium, tender abdomen
-Liver function is abnormal
Patient has ROSE SPOTS among other symptoms – what is the organism?
salmonella typhi!
Treatment for
1) general enterocolitis:
2) enteric fevers, septicemia, severe enterocolitis
1) -self limiting - just give fluid and electrolytes
- antibiotics do not shorten or reduce symptoms –> instead could prolong fecal shedding and possibility for carrier state
- Only give antibiotics if septicemia risk
2) ceftriaxone or ciproflaxin
- chronic carriers of typhi = ampicillin or ciprofloxacin
- may need to perform cholecytectomy to get rid of carrer state
How is resistance transmitted with salmonella?
plasmid mediated antibiotic resistance
E Coli -
1) organism details?
2) where found in environemtn?
3) causes what?
4) antigens which characterize it?
1) -gram neg rod
- ferments lactose = pink on macconkeys
- faculative anaerobe
2) normal GI flora
3) Gastroenteritis, UTI…
4) O (cell wall); H (flagellar); K (capsule)
most travelers diarrhea caused by?
enterotoxigenic E Coli (ETEC)
most common cause of diarrhea in infants?
ETEC!
ETEC gastroenteritis - patient presentation:
- nausea
- vomitin
- abd cramping
- massive watery diarrhea = dehydration
- NO BLOOD
Infective process of GI tract- ETECi:
- Use adhesins to bind mucosa
- release 2 toxins - similar to cholera toxin
- small intestine involved
EIEC ( enteroinvasive E Coli) - presentation, where infect?
- like shigella infection -
- organism enters and grows in large intestine epithelium = cell death
EIEC presentation in patient:
- fever
- cramps
- BLOOD AND PUS IN FECES
EPEC (enteropathogenic E Coli) - most common associations?
- diarrheal outbreaks in hospital nurseries
- bottle fed infants in dev countires
EPEC - what does it cause? What population?
-in infants = CHRONIC watery DIARRHEA w/ mucous
EPEC - where infect & how?
- has plasmid dependent adhesins = LOSS OF MICROVILLI AT SITE OF ATTACHEMNT bc of actin bundle change of shape (pedestal formation)
- Small intestines
Infant with watery diarrhea w/ pus - what organism?
EPEC
EHEC ( enterohemorrhagic E Coli) - most important serotype?
O157:H7
EHEC - infection process?
produces toxins similar to Shigella – EHEC toxins= shiga like toxins (SLT-I and II)
-infects large intestines
EHEC - patient presentation?
- BLOODY DIARRHEA NO PUS
- hemolytic uremic syndrome (due to toxins) = kidney failure and lysis of RBC
E Coli- usual treatments:
- replace fluids
- antibiotics should not be used routinely
E Coli with infants treatment
fluids and gentamycin or polymyxin
E Coli - travelers diarrhea treatment
bismuth or fluoroquinolones
Cholera - symptoms/patient presentation:
Severe watery diarrhea - RICE WATER STOOL
-NO PMNs IN POOP
Patient presents with rice water stools?
-cholera!
Vibrio cholerae - organism details:
curved gram neg rod
vibrio cholerae - pathogenesis?
- exotoxin = cholera toxin=
- A-B subunit - B binds and A activates adenylate cyclase = more cAMP
- heat labile
Cholera treatment:
-REPLACE FLUID AND ELECTROLYTES
Campylobacter jejuni
-associate with which food?
CHICKEN
Does campylobacter jejuni cause diarrhea?
ERR YES – dysentery
Campylobacter jejuni- organism details:
curved gram neg rod
motile
**Which organism can grow under MICROAEROPHILIC conditions?
**Campylobacter jejuni
H. pylori too
Someone went out to eat, got some kind of GI bug, and got better in less than ten days - most likely organism?
-campylobacter jejuni
Campylobacter jejuni - treatment -
usually gets bettter on its own – if severe give erythromycin or ciproflaxin
H. pylori- organism details:
causes what?
- gram neg
- microaerophilic
- short, spiral
- multiple sheathed polar flagella
stomach ulcers!
How does H pylori infect/pathogenensis?
-survive stomach acidity with urease - creates alkaline environemtn making urea into ammonia
