Microreview137B(Invasive Bacterial Diarrhea)

Front 1

What is the clinical course of Shigella?

Back 1

Incubation period of 1-3 days, followed by abdominal cramping, fevers and watery diarrhea for the next 1-2 days. Then bloody mucus stools of low volume with rectal urgency and tenesmus with symptoms resolving after a week.

Front 2

Does everyone with shigellosis get grossly bloody diarrhea?

Back 2

No, only 40% get gross blood, patients with Shigella dysenteriae are more likely to have severe disease than patient with Shigella sonnei or other Shigella species.

Front 3

What is the treatment for Shigellosis?

Back 3

For mild disease, antibiotics are given more to prevent the spread of the bug than to treat the disease. For, severe cases, fluoroquinolones or TMP-SMX is given. As always with diarrhea, fluid replacement is essential.

Front 4

Which species of bacteria that produces a bloody diarrhea can be distinguished from Shighella by their ability to produce H2S>

Back 4

Salmonella

Front 5

Is the ID50 for salmonella higher or lower than Shigella?

Back 5

Much higher. App 100,000 organisms required. The organism is susceptible to gastric acid, so patients on antacid and/or with a gastrectomy are more susceptible to infection.

Front 6

What are the three clinical syndromes that Salmonella can cause?

Back 6

Salmonella enterocolitis, Salmonella bacteremia, and typhoid fever(not the same as typhus). Note that while salmonella enterocolitis is the only syndrome that affects the GI system primarily, the intestine is the portal of entry in all 3 cases.

Front 7

What is the mode of transmission for Salmonella?

Back 7

Domestic pets, poultry and human beings. salmonella typhi is only transmitted by human beings.

Front 8

What is the clinical course of Salmonella enterocolitis?

Back 8

Fever, abdominal cramps bloody or watery diarrhea. 80% of patients will have fecal leukocytes. Symptoms usually resolve within 7 days, though stool cultures can be positive for more than 2 months in 5-10% of patients.

Front 9

What is the treatment for Salmonella enterocolitis?

Back 9

Primarily fluid and electrolyte replacement. Antibiotics should generally be avoided as they do not reduce symptoms or duration of disease and may even prolong excretion of organisms and encourage carrier state. So, ciprofloxacin, TMP-SMX are given only to neonates, patients with chronic disease, atherosclerosis, or immunocompromise.

Front 10

What organin in particular causes typhoid fever?

Back 10

S. typhi

Front 11

At what histologic site does S. typhi replicate during intestinal invasion?

Back 11

Within the macrophages concentrated at Peyer patches. This causes hypertrophy and eventual necrosis leading to severe abdominal pain and subsequent ileal perforation.

Front 12

What is the pathogenesis of typhoid fever during primary bacteremia?

Back 12

After 5-7 days of replication in the Peyer's patches, the S. typhi seeds into the reticuloendothelial system(liver, bone marrow, spleen) through the lymphatic system and blood stream

Front 13

What happens during secondary bacteremia?

Back 13

S. typhi returns to the bowel through roundabout means. After 3-5 days of primary bacteremia, infection is established in the gall bladder where the chronic carrier state can persist. S. typhi can silently shed from the biliary tract into the intestine.

Front 14

What are the symptoms during the stage of intestinal invasion?

Back 14

Few symptoms. Mild abdominal pain and sometimes constipation or diarrhea.

Front 15

What are the symptoms during primary bacteremia?

Back 15

Fever and rose spots on skin of abdomen. Once seeding takes hold in the RES patients have hepatosplenomegaly.

Front 16

What are rose spots?

Back 16

Erythematous macular skin lesions characteristic of S. typhi infections.