Acute infectious diarrheal disease - Salmonellosis - DONE Flashcards
Salmonella:
- gram negative
- non-spore forming
- facultatively anaerobic bacillus
Nontyphoidal serotypes of Salmonella…..
Nontyphoidal serotypes of Salmonella are highly adapted for growth in human and animals
What is restricted to human host?
Only serotypes S.typhi and S.paratyphi are restricted to human host
How many serotypes of Salmonella are pathogenic to humans?
More then 200 serotypes of Salmonella are pathogenic to humans
How does Salmonella infections begin?
All Salmonella infections begin with ingestion of organisms, most commonly in contaminated food or water
What causes the transmission of Salmonella?
Food-borne or water-borne transmission results from fecal contamination by ill or asymptomatic person
What is important determinant of incubation period and disease severity?
Ingested dose of pathogen is important determinant of incubation period and disease severity
Salmonellosis - Risk factors:
- Decreased stomach acidity
- Decreased intestinal integrity
Decreased stomach acidity:
- age less then 1 year
- antacid digestion
- achlorhydric disease
Decreased intestinal integrity:
- inflammatory bowel diseases
- prior gastrointestinal surgery
- alteration of intestinal flora by antibiotic administration
Typhoid (enteric) fever:
Typhoid fever is a systemic disease caused by dissemination of S.typhi or S.paratyphi
- S.paratyphi may cause milder disease
Where does typhoid (enteric) fever occur?
Typhoid fever occurs worldwide, primarily in developing nations whose sanitary conditions are poor
Typhoid (enteric) fever is endemic in:
- Asia
- Africa
- Latin America
- the Caribbean
- Oceania
- but 80% of cases come from Bangladesh, China, India, Indonesia, Laos, Nepal, Pakistan, or Vietnam
Typhoid (enteric) fever - incubation fever:
10-14 days (ranges from 5-21 days)
Typhoid (enteric) fever - symptoms:
- prolonged up to 4 weeks fever (the most prominent symptom) plus fatigue
- headache, malaise, and anorexia are nearly universal
- abdominal pain, diarrhea, or constipation are common
- bronchitic cough is common in the early stage of the illness
What is the most prominent symptom Typhoid (enteric) fever?
prolonged up to 4 weeks fever (the most prominent symptom) plus fatigue
What is common in the early stage of Typhoid (enteric) fever?
bronchitic cough is common in the early stage of the illness
Typhoid (enteric) fever - Clinical findings:
- transient, macular rash of rose-colored spots on the trunk on the end of the first weak of disease, resolves after 2-5 days
- hepatosplenomegaly
- relative bradycardia at the peak of high fever
- gastrointestinal bleeding and intestinal perforation
- meningitis
- neuropsychiatric syndrome (muttering delirium)
Typhoid (enteric) fever - Chronic carriage:
- up to 10% of untreated persons excrete S.typhi in feces for up to 3 months
- 1-4% of patients for more than 1 year
Typhoid (enteric) fever - Chronic carriage are common amongst:
- women
- infants
- persons with biliary anatomic biliary abnormalities and concurrent infections
Typhoid (enteric) fever - Diagnosis:
- Blood culture is the mainstay of the diagnosis.
Definitive diagnosis requires isolating of S.typhi or S.paratyphi from blood, bone marrow, other sterile sites, rose spots, stool, intestinal secretions - The presence of clinical symptoms characteristic of typhoid fever or the detection of a specific antibody response is suggestive of typhoid fever but not definitive.
- Antimicrobial susceptibility testing is crucial for the guidance of clinical management.
Typhoid (enteric) fever - Diagnosis - Laboratory tests: non-specific:
- leukopenia
- neutropenia
- anaemia
- elevated values of liver function and muscle enzyme levels
Typhoid (enteric) fever - Diagnosis - Serologic tests:
Salmonellae can be characterized by their somatic (O) and flagellar (H) antigen
Widal test:
- For Typhoid (enteric) fever diagnosis
- Widal test measures agglutinating antibody levels against O and H antigens.
- Test has only moderate sensitivity and specificity. It can be negative in up to 30% of culture-proven cases of typhoid fever.
Typhoid (enteric) fever - Treatment:
- Appropriate antimicrobials should be administer promptly to prevent severe complications
- Supportive treatment:
- oral or intravenous hydration
- the use of antipyretics
- appropriate nutrition
- blood transfusions if indicated
Drug-susceptible S. typhi and S. paratyphi - treatment:
- fluoroquinolones are the optimal treatment.
- ciproflaxacin or oxofloxacin for 5-7 days
MDR S.typhi or S. paratyphi - Treatment:
- ceftriaxon iv for 10-14 days
- or azithromycin p.o. for 5 days
Chronic carriers – treatment:
4-6 weeks of appropriate oral antibiotic
- e.g. amoxicillin, TMP-SMX, ciprofloxacin, norfloxacin
Typhoid (enteric) fever - prevention:
Prevention is based on ensuring access to safe water, promoting safe food handling practices and by vaccination.
- wash hands
- drink boiled water
- clean fruits and vegetables
- get vaccinated!
Typhoid (enteric) fever - prevention - vaccination:
polysaccharide capsule Vi is present in about 90% of all freshly isolated S.typhi has a protective effect against the bactericidal action of the serum of infected patients
How many vaccines do we have against Enteric (typhoid) fever?
two currently available improved typhoid vaccines
Two currently available improved typhoid vaccines:
- parenteral Vi polysaccharide is given in a single dose with a booster every 2 years subcutaneous or i.m.
- oral live attenuated Ty21a given on days 1, 3, 5, 7 with a booster every 5 years
