Week 2 - Gastrointestinal infections Flashcards
To consider a diarrhea as invasive it needs to cross a layer of the intestinal lumen, which one is it?
Lamina propia
Bacteriemia signs and symptoms
- Shivers
- Piloerección
- Marble skin
Salmonella spp. likes to invade an organ of the GIT, which one is it?
Gallbladder
Uncomplicated Salmonella (non typhi) is treated with what type of antibiotic?
None, since its uncomplicated adding an antibiotic will lead to Salmonella staying @ gallbladder
Principal cause of dysentery
Shigella dysenteriae
Bacterias that grow on SS agar
- Salmonella (black bc of sulfhidric acid)
- Shigella (transparent)
Patient with systemic manifestations (fever, chills, shivers) and inflammatory diarrhea needs lab tests, which ones?
- Blood culture
- Feces culture
Difference between food poisoning and an infection
- Presence of fever in infection
- Food poisoning has a shorter incubation period
- Food poisoning only causes diarrhea, nausea and vomit but NO fever
Entamoeba histolytica doesn’t cause diarrhea and causes colitis, why tf?
Bc it affects the large bowel and NOT the small intestine
Resistant form of Entamoeba histolytic
Cysts (4 nuclei)
Why is blood and mucus seen at feces when infected with Entamoeba histolytic?
Bc it causes ulcers that bleed and produce mucus
Organs that can be invaded by Entamoeba histolytic
- Liver
- Lungs
- Brain
Virulence factor present in Entamoeba histolytic
Lectin
Characteristics of enteric fever
- Caused by Salmonella typhi
- Febrile illness
- Starts with fever, arthralgia, astenia, myalgia and general discomfort
- 2 weeks later starts with inflammatory diarrhea
- Bradycardia
Characteristic dermatological manifestation of enteric/ typhoid fever
Rose/ red exanthema rash at back
Zoonoses is caused by
Yersenia
Rotavirus is a…
- Non-Enveloped | naked
- RNA virus | double stranded
- Double icosahedral capsid
Leading cause of dehydration due to enteritis (childhood and infants)
Rotavirus
The stomach flu is caused by…
Rotavirus
There are 8 strains of Rotavirus A-H, which one is the one associated with the “stomach flu”
Rotavirus strain A
Rotavirus is part of the reovirus family, and REO stands for…
- R: respiratory
- E: enteric
- O: orphan
Rotavirus is transmitted via
Fecal-oral route (ingesting poop or vomit)
- Fluids
- Fingers
- Fields
- Flies
Clinical manifestations of Rotavirus
- Gastroenteritis
- Diarrhea (watery|malabsorption) and vomiting (acute onset)
- Can lead to severe dehydration
- Low grade fever
Complications of Rotavirus
- Severe dehydration
- Temporary lactose intolerance
- Seizures when rotavirus is present @ CSF
Virus associated with intuception
Rotavirus
Pathogenesis of rotavirus
- Infects epithelial cells @ small intestine
- Causes malabsorption due to epithelial cell loss
- Production of enterotoxin
- Damage to Enteric Nervous System
Rotavirus decreases the activity of some digestive enzymes produced by the enterocytes, which ones?
- Lactase
- Maltase
Rotavirus’ production of… causes enterocyte death, leading to them being replaced by new loser underdeveloped enterocytes
Non-structural protein 4
Epidemiological characteristics of rotavirus
- Universal infection during the first years
- Can cause a severe sickness between 6M and 2 years old
- 450,000 deaths in children
There aren’t any vaccines for Rotavirus (V/F)
False, there are 2 vaccines for rotavirus:
- Rotarix: monovalent vaccine
- RotaTeq: pentavalent vaccine
- Live attenuated oral vaccine
Reinfection is common throughout life when it comes to Rotavirus
True
Diagnosis for Rotavirus
- Specific virologic diagnosis isn’t useful nor necessary
- Antigen detected @ stool: enzyme-linked immuno-sorbent assay
Name of the specific treatment for Rotavirus
- There isn’t any specific treatment
- Hydration and supportive treatment
Why can’t someone infected with rotavirus take antidiarrheals
Bc it’ll slow down clearing of the virus
What kind of supplementation should you give to a patient with malnutrition that presents with Rotavirus
Zinc supplementation
Outer capsid proteins present in Rotavirus viral structure
- VP8
- VP5
- VP7
Intermediate capsid proteins present in the Rotavirus viral structure
VP6
Enterobacteriacea characteristics
- Gram -, non-spore forming
- Facultative anaerobes (ferment glucose)
- Coverts nitrate to nitrite
- Produce catalase
- Oxidase negative
- Urease +
- Grow on MacConkey agar
- Some can ferment lactose (pink colonies)
Enterobacter virulence factors
Fimbriae
Which bacterias form part of the enterobacteriacea squad?
- Salmonella
- Escherichia coli
- Proteus
- Klebsiella
- Citobacter
- Yersenia
- Shigella
Diagnosis techniques for enterobacteriacea
- Standard culture
- Immunoassays
- PCR
- Gel electrophoresis
Name the vaccine for all of these bacteriacea
There isn’t any vaccine
Enterobacteria that acts on the small intestine, causes traveler’s diarrhea, has a plasmid-mediated pathogenesis plus ST and LT enterotoxins
ETEC
Enterotoxins released by ETEC
- Heat-labile enterotoxin
- Heat stable enterotoxin
Inflammation @intestines - fluid @ intestinal lumen that then produces watery diarrhea
ETEC causes intestinal wall destruction, therefore bleeding
False
Enterobacteria that acts on the small intestine, causes infant diarrhea in developing countries (rare @USA), has a plasmid-mediated pathogenicity plus disruption on normal microvillus structure
EPEC
EPEC causes disease @ what specific age group
Children under 2 yo
What type of diarrhea does EPEC cause
Malabsorptive diarrhea because the cells flatten
Diagnosis for Traveler’s diarrhea (ETEC)
Commercial immunoassays
Diagnosis for EPEC
Characteristic adherence to Hep-2 or HeLa cells
Enterobacteria that acts on small intestine, causes infant diarrhea in developing/ developed countries, has a plasmid-mediated aggregative adherence to rods (shortening microvilli)
EAEC
Diagnosis for EAEC
Characteristic adherence to HeP-2 cells
Enterobacteria that acts on large intestine, starts with watery diarrhea and them followed by bloody diarrhea; pathology mediated by Shiga toxin plus destruction of microvilli
STEC
Diagnosis for STEC
- Screening for O157:H7 with sorbitol-MacConkey agar
- Immunoassays
- DNA amplification assays
Enterobacteria that acts on large intestine, rare in developing and developed countries, that causes fever, cramping and watery diarrhea. Plasmid-mediated pathogenesis + destruction of cells lining the colon
EIEC
Where does EIEC replicate
Inside the intestinal lumen
Enterobacteria that can progress to hemolytic uremic syndrome
STEC
Enterobacteria that may progress to dysentery + bloody scant stools
EIEC
UPEC causes UTIs in what percentage
- 90% of community acquired UTIs
- 50% of hospital acquired UTIs
Does UPEC cause cystitis or polynephritis?
BOTH
Diagnosis for EIEC
- Sereny test
- Plaque assay in HeLa cells
Characteristics of E. coli
- Gram -
- Catalase +
- Lactose fermentor
- Facultative anaerobe
- Encapsulated
- Flagela
- Grows in eosin agar
Antigens present in E. coli
- O: somatic
- K: capsular
- F: fimbrial
- H: Flagellar
K1 E. coli is associated with
Neonatal meningitis
- Hemorrhagic colitis
- Hemolytic Uremic Syndrome
- Diarrheal outbreaks are all associated with what type of E. coli
E. coli O157:H7
Characteristics of a moderate fluid loss
- Irritable children
- Thirst: moderately increased
- HR: elevated
- BP: normal or slightly reduced
- RR: elevated with deep inspiration
- Eyes: sunken orbits
- Capillary refill: delayed 2-3 seconds
- Urine output: moderately decreased
- Anterior fontanelle: sunken
Moderate fluid loss in percentage
6 to 9%
Characteristics of severe fluid loss
- Lethargic
- Children: irritable
- Thirst: extreme but too lethargic to drink
- HR: tachycardia or bradycardia
- BP: hypotensive
- RR: Kussmaul breathing
- Eyes: deeply sunken orbits + NO tear production
- Capillary refill: delayed > 3 seconds
- Urine output: oliguria or anuria
- Anterior fontanelle: markedly sunken
Severe fluid loss in percentage
> 10%
Enterobacteria that can ferment lactose
Escherichia coli
Which E. coli causes watery diarrhea + vomiting
- EPEC: Enteropathogenic
- ETEC: Enterotoxigenic
- EAEC: Enteroaggregative
Which E. coli causes watery than bloody diarrhea
- STEC: Shiga toxin-producing
- EHEC: Enterohemorragic
FUN FACT: son lo mismo on god
Which enterobacteria can lead to a severe infection
EIEC (similar to Shigela)
What increases the risk of hemolytic uremic syndrome
Antibiotics
Where can E. coli grow (media cultures)
- MacConkey’s agar (pink color)
- Eosin methylene blue (green color)
Extra-intestinal infections caused by E. coli
- Opportunistic pathogens
- Commensals
- UTI or neonatal meningitis
Mechanism of contagio of enterobacter
- Endogenous: ppl who take a lot of antibiotics
- Exogenous: direct/ indirect contact
“Coma shaped” gram - bacteria, that causes diarrhea even though it’s considered noninvasive
Vibrio cholerae
Microbiological characteristics of V. cholerae
- Gram negative coma shaped
- Oxidase positive
- Grows @ alkaline media
- Has a singular flagellum
- Facultative anaerobe
Which V. cholerae causes epidemic cholera
O1 and O139
What causes the secretory diarrhea present in a Vibrio cholerae infection
Cholera toxin
V. cholerae has a reservoir, where?
Aquatic reservoir at brackish estuarine water