30 Questions
Which of the following is the primary mode of transmission of Shigella?
Fecal-oral
A 28-year-old male has been diagnosed with typhoid fever. What is the most common source of transmission for Salmonella typhi?
Contaminated water
A child is brought to the emergency room with bloody diarrhea and dehydration. Shiga toxin is detected in the stool sample. What complication should be closely monitored in this patient?
HUS
Which one of the following organisms is gram -ve, non-lactose fermenter, +ve O antigen and -ve Vi and H antigen?
Shigella
A 48-year-old patient presented with salmonella gastroenteritis. Which of the following morbidities requires mandatory antibiotic therapy?
Sickle cell anemia
A patient came with abdominal cramps, fever and bloody diarrhea. Microbiology lab isolated an organism that was suspected as salmonella spp. or shigella spp. Which one of the following is a differentiating test between the two organisms.
Production of H2S
What is the most likely diagnosis for the 4-year-old child presented with fever, diarrhea, and skin rash?
Typhoid fever
What do you expect the blood culture to show for the child presented with fever, diarrhea, and skin rash?
Positive for salmonella typhi
What caused the growth of black colonies on XLD media for the child presented with fever, diarrhea, and skin rash?
H2S production by salmonella spp.
What are the causes of infectious diarrhea mentioned in the text?
Campylobacter, Yersinia, Salmonella
What is the incubation period for Shigella infection?
1-2 days
What is the main antigen on the cell membrane of Salmonella typhi?
Vi
What is the infectious dose for Shigella?
$200$ organisms
How is Salmonella differentiated from Shigella?
Motility, antigen on cell membrane, non-lactose fermentation
What media is used to differentiate between Salmonella and Shigella?
HEA
What are the medical treatments mentioned for Salmonella and Shigella infections?
Ceftriaxone, Azithromycin, and/or other antibiotics as needed.
Which Salmonella subspecies is mentioned in the text?
S. Enteritidis (IIIa)
What are the antigenic factors mentioned for Salmonella?
Somatic (O) and flagellar (H)
Which infection is caused by Salmonella serotype typhi or S. paratyphi A, B, and C?
Typhoid fever
What are the sources of Salmonella infections mentioned in the text?
Contaminated food, water, and human or animal excreta
Which species causes bacillary dysentery?
S. dysenteriae (group A6)
What are the risk factors mentioned for Shigella infections?
Young children, young adults, crowded areas, and anal-oral sex
What is the recommended treatment for Salmonella and Shigella infections?
Antibiotics
Which of the following statements about Salmonella is correct?
Salmonella is a gram-negative, motile, facultative anaerobic bacilli
Where are Salmonella species usually found?
In warm-blooded animals like birds and rodents
Which type of climate is associated with the highest prevalence of Salmonella infections?
Tropical climates during the rainy season
How many species of Salmonella are there?
Two: S. enterica and S. borgori
Which subspecies of Salmonella is associated with 1504 serotypes and usually found in warm-blooded animals?
$S. enterica$ subsp. enterica (I)
Which type of animals are known to carry Salmonella?
Birds and rodents
What are the characteristics of the colonies formed by Salmonella on appropriate media?
Non-lactose fermenting colonies
Study Notes
- Three infections discussed: food poisoning, gastroenteritis, and typhoid fever
- Salmonella (S.) infections:
- Three subspecies mentioned: Enteritidis (IIIa), Diarizonae (IIIb), and Houtenae (IV)
- Total of 2541 S. Enterica bacteria
- Important Salmonella virulence and antigenic factors:
- Antigenic factors: somatic (O) and flagellar (H)
- Vi capsular antigen: labile, protects Salmonella from phagocytosis
- Infections caused by Salmonella:
- Salmonella gastroenteritis: caused by S. enterica subsp. Enteritidis, incubation period 8-36 hours, symptoms include fever, diarrhea, abdominal pain, and nausea
- Typhoid fever: caused by Salmonella serotype typhi or S. paratyphi A, B, and C, incubation period 9-14 days, symptoms include fever, headache, constipation, and rash
- Sources of Salmonella infections: contaminated food, water, and human or animal excreta
- Shigella infections:
- Bacillary dysentery: causes bloody diarrhea, mucus, and pus in the stool
- Four species: S. sonnei (group D1), S. flexneri (group B15), S. dysenteriae (group A6), and S. boydii (group C20)
- Shigella species have O antigens and some have K antigens, which are heat-labile and removed by boiling
- Shigella infections risk factors: young children, young adults, crowded areas, and anal-oral sex
- Shigella infections symptoms: high fever, diarrhea, abdominal pain, and tenesmus
- Treatment for Salmonella and Shigella infections: antibiotics to reduce duration of illness
- Complications of Salmonella and Shigella infections: ileus, obstruction, toxic megacolon, bacteremia, seizures, hemolytic-uremic syndrome, and meningitis
- Diagnosis methods: stool culture and serotyping using agglutination agar test for Salmonella, Shigella, and E. coli.
Test your knowledge on the classifications of diarrhea, including infectious and non-infectious diarrhea and the common organisms responsible for infectious diarrhea such as Campylobacter, Yersinia, and Salmonella. Explore the characteristics and treatments for each type of infectious diarrhea.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
