Bailey Lecture 2 Gram - Mucosal Pathogens Flashcards
What are the two toxin-producing bacterial genuses?
Vibrio & Entertoxigenic E. coli
cholerae, parahaemolyticus, vulnificus, & alginolyticus are all species of what genus?
vibrio
What are the two main types of Vibrio cholera?
1) El Tor
2) Classical
What antigen did the El Tor strain of cholera mutate?
O1 antigen
What ages of people and what percentage of people did the El Tor O139 encapsulated bacteria effect?
it affected all age groups and about 1 in 20 people (5%)
What are the 3 virulence factors of V. cholerae?
1) flagella
2) pili (to adhere to mucosal tissue)(shift from saltwater’s high ion concentration to the body’s low ion concentration leads to pili expression)
3) cholera toxin (phage encoded)
What is the end effect of V. cholerae and what is it similar to?
In the end, V. cholerae causes an increase in the intracellular cAMP (by way of adenylene cyclase) and an increase in intracellular cGMP in mucosal cells of the intestine causing evacuation of Cl and H2O leading to diarrhea
30-45% of cases of traveler’s diarrhea (Mexian) are the direct result of which strain of e. coli?
ETEC (enterotoxigenic e. coli)
does ETEC (enterotoxigenic e. coli) have a large or small infectious dose?
large
____ on the fimbrae of ETEC (enterotoxigenic e. coli) help it adhere to mucosal tissue
colonization factor antigens (cfa)
What two toxins are responsible for the traveler’s diarrhea caused by ETEC?
1) heat-labile toxin (LT)
2) heat-stable toxin (ST)
What does heat-labile toxin produced by ETEC activate?
it activates adenylene cyclase resulting in an intracellular increase in cAMP
In ETEC, what does ST (heat-stable toxin) activate?
ST causes an intracellular increase in cGMP
What types of food typically leads to V. cholerae?
shellfish
Match the antibiotic with the infection:
Tetracycline
Flouroquinolones
ETEC
Vibrio infection
tetracycline for vibrio infection and 2nd generation flouroquinolones for ETEC
What specific types of bacteria are the “hybrid misfit” strains we have been talking about?
1) EPEC (enteropathogenic e. coli)
2) EHEC (enterohemorrhagic e. coli)
What type of e. coli is prevalent in newborns and causes noninflammatory secretory diarrhea?
EPEC (enteropathogenic e. coli), is present in the DISTAL small intestine, has a large infectious dose, has an ABSENCE of traditional endotoxins (such as those found in ETEC) and has a characteristic intimate adherence pattern (aka an attaching and effacing lesion)
The following is an image showing the three main steps in EPEC & EHEC adherence which is intimate (AKA attaching and effacing) note that the “syringe” in the second stage is called a type III secretin and that the final result is the bacterium on a pedistal on the cell
Since there is no toxin production with EPEC, what is the cause of diarrhea?
the cause is malabsorption of nutrients and water due to the disruptions to the microvilli and epithelial tight junctions as a result of the pedistal formation
EHEC has a set of EPEC genes that produce an attaching effacing lesion just like EPEC but is much more dangerous due to what?
the fact that the toxin produced can lead to hemolytic uremic syndrome (bleeding in the urine)
What is the primary reservoir for EHEC?
cattle. note that EHEC produces what’s called a “shiga-like” toxin which causes hemorrhagic colitis as well as hemolytic urine syndrome (HUS), causing 250-500 deaths annually
EHEC can be diagnosed on an agar plate because it cannot do what?
cannot ferment sorbitol
“Other” mucosal surfaces include the urinary tract and the respiratory tract. Which organisms connonly infect each of these respectively?
urinary tract: Proteus species and UPEC
respiratory tract: Klebsiella species
What is the most common bodily infection besides those in the mouth?
UTI (most frequent reason for doctor visit) Remember that inflammation in the bladder is termed cystitis
Which genus is most responsible for cases of uncomplicated UTIs?
e. coli. (80%). For complicated UTIs, e. coli only account for 20% (enterobacteriaceae such as pseudomonas aeruginosa and serratia accounting for the other 80%)
Where will a complicated UTI likely spread?
kidneys (calledpyelonephritis)
How to UPEC (uropathogenic e. coli) adhere to uroepithelial cells?
via fimbriae
_____ produces aerobactin and hemolysin
UPEC
P. mirabilis is a common cause of _____
uncomplicated UTI
If you have an abnormal urinary tract structure, you are you more likely to have a UTI from UPEC or from P. mirabilis?
p. mirabilis
Is a P. mirabilis UTI or an E. coli UTI more severe?
P. mirabilis
What type of protease does P. mirabilis carry?
IgA protease
urease does what to the pH of urine?
raises it (note that urease is a virulence factor of P. mirabilis). Bacteria will grow better in a lecc acidic environment but urease is toxic to renal cells. This can lead to the formation of urinary stones
In an individual with dysuria (urinary infection), is the bacterial concentration in the urine higher or lower than normal?
Lower (at least with pyuria)
What are the best two factors that can help with a proteus UTI infection diagnosis?
1) constantly alkaline urine
2) production of urease
What is notable about agar colonies of Klebsiella?
large mucoid colonies due to their large capsule
Do Klebsiella have pili?
yes they do, two types
Type 1: important for adherence to urinary tract epithelial cells
Type 3: important for adherence to respiratory tract epithelial cells
Do Klebsiella contain enterotoxins?
yes, they are similar to ST & LT and therefore induce secretory diarrhea
What does aerobactin do?
it sequesters iron
What is the PRIMARY virulence factor for Klebsiella?
the antiphagocytic capsule
What type of bacteria is known to transfer via oral to oral contact?
Helicobacter (transmits from fecal-to-oral as well) and is a GI bacteria
Is helicobacter a fast or slow bacterium?
it is a slow bacteriumthat is only found in the mucous overlying mucous secreting cells of the stomach
What type of bacteria we have discussed are readily killed by gastric acid?
H. pylori. It is an efficient producer of urease, causes epithelial cells to release IL-8, has a cytotoxin associated with peptic ulcer disease, and downregulates somatostatin-producing D-cells
Treatment for _____ is intense with many side effects
H. pylori
