Enterobacteria II Flashcards
What are the features of Shigella?
Biochemically and antigenically similar to E. coli but has some DIFFERENCES:
Non-lactose fermenter
Non gas producer
Nonmotile
What is the main transmission of Shigella?
Fecal-oral route
What is the pathogenesis of Shigella?
Virulent strains carry plasmid for attachment and entry
Enters cells by phagocytic vacuole
Organism escapes in cytoplasm
Intracellular replication
Actin “tail” drives organism in cytoplasm
Organisms enter adjacent cells
What diseases does Shigella cause?
Bacillary Dysentery
What are the main symptoms of Shigella infection?
Abdominal cramps, tenesmus, pus and blood in stool
What does E. tarda cause?
Gastroenteritis
What are the symptoms of E. tarda infection?
Acute, self-limiting gastroenteritis with watery diarrhea
Typhoid-like illness with bloody diarrhea and possible
fever, nausea, vomiting, colonic ulcerations and terminal ileum nodularity
What is the reservoir of Salmonella?
Poultry, cows, pigs, pets for nontyphoid strains
Humans for S. typhi
What is the reservoir of Salmonella?
Poultry, cows, pigs, pets for nontyphoid strains
Humans for S. typhi
What are the characteristics of Salmonella?
Gram Negative
Non-lactose fermenter
Produces hydrogen sulfide (black)
What are the routes of transmission of Salmonella?
Contaminated poultry and poultry products
Also associated with reptiles
What are the 5 Salmonella clinical syndromes?
- Asymptomatic Carrier
- Febrile Gastroenteritis
- Enteric Fever (as in Typhoid Fever)
- Septicemia
- Focal Infections
What is the only reservoir of S. typhi?
Humans
What is the pathogenesis of Salmonella?
Bacteria bind to M cells
Infection kills cell, bacteria go to Peyer’s
patches
Organisms invade macrophages where they multiply
Inhibition of oxidative metabolic burst allows organisms to survive intracellularly
What are the clinical manifestations of Salmonella enteric fever?
Presents with fever, headache, rose spots, constipation
What is the treatment for Salmonella bacteremia?
3rd Generation Cephalosporin
A 50 year old female returned to Chicago from a 3 week trip to Jakarta (Indonesia) and about 5 days later started having flu like symptoms and a low grade fever. On the day prior to admission she had spiking fevers followed by profuse sweating. Stool cultures, ova and parasite exams and urine cultures were all negative. The blood culture collected after a spiking fever episode grew a glucose-fermenting, gram-negative rod that was oxidase negative. Additional testing showed the organism was lactose-negative and H2S positive. What is the likely etiologic agent of this patient’s symptoms?
A. Shigella B. E.coli O157 C. Malaria (Plasmodium falciparum) D. Salmonella typhi E. Vibrio cholera
D. Salmonella typhi