#Yersinia, Campylobacter + Helicobacter Flashcards
Three important pathogenic Yersinia spp are __
Y pestis – causes bubonic plague
Y enterolitica – causes bloody, inflammatory diarrhea (this one’s the one you’ll likely see in the US)
Y pseudotuberculosis – similar to Y enterolitica
Yersinia morphology, gram staining, enzymes etc
Gram negative motile (flagella) oxidase +ve curved rod
Y enterocolitica is part of the normal flora of ___. Causes foodborne gastroenteritis, primarily from ingestion of contaminated __
Y enterocolitica is part of the normal flora of farm animals (sketchy says pets also). Causes foodborne gastroenteritis, primarily from ingestion of pork
Y enterocolitica likes to grow in __ temperatures (hence why you can also find it in contaminated milk)
Cold temps
Dx for Y enterocolitica
stool culture (slow lactose fermentation on McConkey agar)
Rx for Y enterocolitica
Rx: antibiotics not usually helpful but if sensitive isolate, use cephalosporins
Yersinia generally colonizes the ___ in the distal small intestine/proximal colon following entry thru M cells
The bug avaoids killing by macrophages via __ released by a Type 3 secretion system
The hallmark of Yersnia infection = ___
Colonizes Payer’s patches and lymphoid tissue following invasion into M cells
Avoids killing by macrophages via YOP proteins (yersinia outer membrane proteins) that are released by a type 3 secretion system
Hallmark of Yersinia infection = neutrophil influx (again Yersinia likes to hang out in lymphoid tissue)
**replicates extracellulary so can cause abscesses or lesions**
Yersinia can sometimes be mis Dx’d as ___
Appendicitis (yersinia mimics appendicitis)
Presentation of Yersinia infection
Rx of Yersinia infection
Fever, vomiting, inflammatory and/or watery diarrhea
Rx for Yersinia: cephalosporins + aminoglycosides with severe/complicated disease (ceftriaxone w/ gentamicin or ciprofloxacin)
The virulence factors that Yersinia pestis has that the others don’t are ___
f1 capsule
Plasminogen activator
(all Yersinia have a Type III Secretion system)
___ is the main Campylobacter pathogen and causes traveler’s diarrhea
C jejuni
C jejuni infection is ass’d with ___(type of meat) and transmission is via __
Campy – often associated with poultry; lives in the guts of animals so transmission = fecal/oral
**remember the camp fire with the chicken roasting**
**can also be transmitted by ingestion of raw milk**
Campylobacter morphological/enzyme/gram stain characteristics
Gram negative CURVED microaerophilic rod (oxidase +ve)
Motile
Campy causes an __ diarrhea (like Salmonella and Shigella) and requires a __ infectious dose
Causes bloody inflammatory diarrhea like Salmonella and Shigella
Low infectious dose
Rx for campylobacter infection includes __ if given only within frst 72 hrs
Rx: azithromycin (only effective within 72 hrs)
Campy infection can lead to ___ (ascending paralysis) via cross-reacting surface antigens
Guillain-Barre syndrome (ascending paralysis, contrast with botulism which causes descending paralysis) – antibodies made against a specific call wall structure of Campy can attack host neurons (which have a similar looking structure on their surfaces #molecularmimicry)
**about 1-3 weeks post infection**
Virulence factors of Campylobacter
Flagella (invasion)
CDT (cytolethal distending toxin) - host cell cycle arrest
Altered flagellin (avoid TLR5) and high AT content (avoid TLR9)
A 26-yr old medical student presents with diarrhea and abdominal pain after eating chicken and pork in the previous 5 days. A typical Gram-negative rod, that is lactose-negative on MacConkey agar is cultured from the stool. What is the most likely pathogen?
A.Campylobacter
B.Yersinia
C.Shigella
D.Salmonella (NTS)
E.S. Typhi
B, C or D (what the actual heck bruh)
Helicobacter pylori characteristics (morphology, gram staining etc)
Gram negative, microaeropholic, motile, helical, oxidase +ve rod
H pylori mostly affects the __ and __
Stomach and duodenum
Transmission of H pylori:
Person-to-person
Fomites
Food/water
Chronic H. pylori infection is the most important
etiological factor for ___
Chronic H. pylori infection is the most important
etiological factor for gastric cancer
The most important virulence factor in H pylori is ___
The most important virulence factor in H pylori is urease
**The conversion of urea to NH3 and CO2 allow for the neutralization of stomach acid, making an environment for the bug to #thrive**
Outcomes of H pylori infection (3)
Gastritis in the pyloric region of the stomach results in __
Gastric ulcer or gastric cancer
Chronic gastritis
Duodenal ulcer
Pyloric region gastritis >> hypersecretion of acid
H pylori virulence factors:
Flagella
__ (creates alkaline environment)
Modified LPS
Toxins (__ and ___)
Flagella - move thru mucous
Urease (creates alkaline environment)
Modified LPS (evade TLR4)
Toxins (VacA - forms holes in epithelial cell membrane and cagA – higher risk of severe disease and cancer)
Role of H pylori Type IV secretion system and CagA
H pylori has a Type IV secretion system and release of CagA causes the following:
IL8 mediated inflammation
Actin polymerization >> change cell shape to Hummingbird phenotype
What is one thing about the H pylori infectious process that is unique to it?
Unique to helicobacter: H pylori triggers host immune response but the infection itself isn’t cleared
H pylori Dx
Endoscopic: urease test/tissue biopsy/histology
Non-endoscopic: serology/urease breath test
**Urease breath test: patient ingests labeled solution of urea which makes its way to the gut. If the pt has H pylori, the urea will be broken down to ammonia and CO2, then the CO2 (radiolabeled) amount is measured**
H pylori Rx
Triple therapy:
PPI, amoxicillin/metronidazole, clarithromycin
Antibiotic treatment is indicated for infections due to which of the following pathogens:
A.Salmonella (NTS) and Yersinia
B.Helicobacter, S. Typhi, and Shigella
C.Campylobacter and Shigella
D.Campylobacter and Salmonella (NTS)
B
