Enteric bacteria

Question 1

what is the O and H antigen

Answer 1

O- LPS

H- flagellum

Question 2

Cholera

Answer 2

Cholera toxin AB-Adenylate cyclase
TCP-coregulated Pilus–> colonization
shellfish-oral-fecal

rice water diarrhea, leg cramps

Tx- rehydration, tetracycline in severe cases

Question 3

ETEC

Answer 3

common source of travelers diarrhea
watery diarrhea
non-invasive
Tx- oral rehydration, maybe doxy or FQOLNS

heat stabile toxin–>GC–> cGMP
Heat labile toxin–> AC–>cAMP

Question 4

EPEC

Answer 4

watery diarrhea in children in the developing world

Adherence:  bundling forming pilus 
   attaching and Effacing lesion 
   Type III secretion system 
    translocated intimin receptor 
    Pedestal formation  
Loss of microvilli:  
malabsorption

Question 5

EHEC

Answer 5

no fever, bloody diarrhea/ initial watery diarrhea
sorbitol neg, lactose pos
O157H7

VIRULENCE FACTORS 
•Forms attaching/effacing lesions 
•Shiga toxins-inactivates 60 s ribsome by removing adenosine from rRNA
       •Inhibit protein synthesis 
•AB toxins 
hemolytic uremic syndrome in children 
-acute renal injury 
-thrombocytopenia
-hemolytic anemia
•severe in young and old 

NO ABX
food borne

Question 6

Shigella

Answer 6

PATHOGENESIS
Invasion of colonic M cells
-Type III secretory system
Apoptosis of macrophages
-Type III secretory system
-IL1 production
Entry of enterocytes
-Type III secretory system
-IL8 production
Cell-cell spread
-IcsA
-IL1 and IL8 attract PMN

SYNDROME
lower abdominal cramps
blood mucous pus diarrhea fever
HUS in dysentary

Question 7

Salmonella Typhi

Answer 7

causes typhoid

Question 8

Salmonella

Answer 8

Nontyphoidal salmonellae- S. Typhimurium, S.
Enteritidis
-food poisoning, watery diarrhea, self-limiting , fever,
-neutrophils
-Disseminated in HIV-infected people
-dont use ABX

Typhoidal salmonellae-Human adapted, S. 
Typhi
-Enteric fever, systemic disease, fever,  
-mononuclear phagocytes 
-kills immunocompetent people 
-gallbladder biofilms
-capsule
-Use ABX
-Vaccine (live attenuated or (capsular antigen))

Question 9

salmonella virulence factors

Answer 9

VIRULENCE FACTORS.

Invasion

• Salmonella pathogenicity island 1
• SPI1 type III secretion system

Survival in macrophages

• Salmonella pathogenicity island 2
• SPI2 type III secretion system

Capsule
-immune invasion

Question 10

Campylobacter Jejuni

Answer 10

gullwing in shape gram -
fecal oral, milk poultry, meat, pets
42 degress, microaerophilic

most common cause of gastroenteritis
-bloody diarrhea in children

Question 11

Campy virulence

Answer 11

Colonize distal ileum and colon 
Motility- for penetration of intestinal mucus 
Flagella are essential 
Invasive 
in vitro
 - tissue culture 
Toxins - 
cytolethal
 distending toxin 
Induces inflammatory response

vomiting fever, bloody diarrhea, cramps

Question 12

H. Pylori

Answer 12

motility
–penetrate gastric mucus, colonize more neutral pH region -close to epithelium 
UREASE
 -neutralizes acidity 
VacA
-epithelial damage 
cag+ pathogenicity island:  
-gastric and duodenal ulcers, inflammation

Question 13

H. Pylori Tx

Answer 13

PPI, Bismuth, Clarithro, Metronidazole, amox