Enterobacteriaceae III Flashcards
Frequent passage of stool containing blood and mucus, straining and painful defecation
Dysentary
Shigella:
S. sonnei, S. flexneri, S. dysenteriae, S. boydii
Disease
Pathogenesis
Diagnosis
Treatment
Dysentary (voluminous watery stool) - common cause of outbreaks (foodborne, daycare centers, contaminated water) - also fever, abdominal cramps
Invades colonic epithelial cells and survives low gastric pH, multiplies in small intestine cells, spreads to adjacent cells, causes inflammation and ulceration and destroys colonic mucosa
Stool culture, assay for Shiga toxin, fecal leukocytosis
Antibiotics, replace lost fluids, avoid antimotility agents
Shigella species that is foodborne
S. sonnei
Shigella species that is sexually transmitted during male-male sex
S. flexneri
What is the infectious dose of shigella?
10-100 organisms (VERY LOW)
What population is incidence of Shigella infection highest in?
Kids ages 1-4
What are possible immunologic complications of enteric infection?
What HLA type has highest risk?
Post-infection reactive arthritis (ReA) (aka Reiter’s syndrome) - arthritis, urethritis, conjunctivitis
- HLA-B27 assoc w/ risk
Erythema nodosum - nodular lesions that lack discrete borders
Inflammation where tendon attaches to bone
Enthesopathy
Small hard nodules on soles of feet
Keratoderma blenorrhagica
Two types of infections caused by Salmonella
Gastroenteritis (nontyphoidal)
Typhoid or enteric fever (not typphus)
Salmonella gastroenteritis
Sources of infection
Symptoms
Treatment
- Food items (raw poultry, eggs, dairy), peanut butter
- Pets - turtles, lizards, etc.
Nausea, vomiting, diarrhea (non-bloody)
Fevers, cramps, chills ,headache
Treatment: antibiotics only for at-risk patients
Salmonella - pathogenesis (3 routes)
Intestinal: Ingested, passes to intestine through M cells, bacterial mediated endocytosis
Typhoid fever: bacteria pass through mucosa, enter Peyer’s patches, invade macrophages and spread
Enterocolitis: intestinal invasion and neutrophil recruitment triggers inflammation
Salmonella gastroenteritis
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Salmonella bacteremia occurs much higher in what population?
HIV patients, if recurring, it’s an AIDS-defining illness
What bacteria causes typhoid fever? What is the reservoir for these organisms? Where in the body do bacteria disseminate?
Salmonella typhi and Salmonella paratyphi
Reservoir: humans and primates only
Spread to spleen, bone marrow, gall bladder
What condition?
- Enterocolitis w/ or w/o diarrhea
- Low grade fever –> high grade
- Headache, malaise, chills, muscle pains
- Bradycardia
- Rose spots
Diagnosis?
Complications?
Lab findings?
Enteric fever
Diagnosis: blood or bone marrow biopsy
Complications: Delirium, psychosis, intestinal perforation
Lab: Leukopenia, anemia, elevated LFTs
What types of antibiotics are ineffective against intracellular bacteria?
What antibiotics is often used instead?
Aminoglycosides
Quinolones, 3rd gen cephalosporins)
What vascular complication can result from Salmonella infection?
Mycotic aneurysm of aorta
What is chronic carriage? Risk factors for it?
Defined as persistence of organism in stool for > year
Risk: biliary abnormalities
Yersinia enterocolitica
Pathogenesis
What does it mimic? What toxin does it produce? Symptoms? Increased risk for infection? Diagnosis Antibiotics
Natural host?
Ingestion followed by mucosal ulcerations in terminal ileum, necrosis of Peyer’s patches, enlargement of mesenteric nodes
Mimics appendicitis
Heat-stable toxin (similar to Shiga toxin)
Symptoms: Diarrhea, fever, vomiting, ab pain, bloody stools, mesenteric adenitis (fever, RLQ pain, leukocytosis)
Risk: Iron overload
Diagnosis: routine culture, cold enrichment
Antibiotics: for septic patients
Natural host: zoonotic! (often isolated in pig GI tract)
What species of Yersinia can grow at 4 degrees Celsius?
Y. enterocolitica - grows well on refrigerated blood products (meat)
Yersinia pestis
What disease?
Stains?
How is it transmitted?
Symptoms?
Plague
Bipolar staining - “safety pin” appearance
Bite of infected flea - bacteria proliferate in regional LN’s
Symptoms: fever, chills, weakness, headache, bubos (intensely painful, swollen node), bacteremia –> septic shock, purpura, necrosis of fingers and toes from vessel blockage
3 clinical forms of plague
Bubonic - bubos
Septicemic
Pneumonic - rapid, hemorrhagic pulmonary failure
Pathogenesis of pneumonic plague
Bacteria from blood invade lung and cause pneumonia, coughing creates aerosols which can spread to other people
