SALMONELLA INFECTION

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SALMONELLA INFECTION

• Abdelaziz Elamin, MD, PhD, FRCPCH
• College of Medicine
• Sultan Qaboos University

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INTRODUCTION

• Discovered in 1880 named after Daniel Salmon,
  the pathologist who first isolated the organism
  from porcine intestine.

• Salmonella is a motile, gram-negative,
  rod-shaped bacteria, which is a leading cause of
  bacterial food-borne diseases.

• Of the 2000 strains recognized, human infection
  are caused mainly by 5 serotypes, typhi,
  paratyphi, typhimurium, choleraesuis
  enteritidis.

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TRANSMISSION

• Infection follows ingestion of contaminated food
  or water. Meat, poultry, eggs diary products
  are frequent sources.

• Pets, domestic animals and infected human are
  potential reservoirs. Person to person animal
  to human transmission is recognized.

• In healthy humans a dose of about one million
  bacteria is necessary to produce symptoms.

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PATHOPHYSIOLOGY

• After ingestion salmonella must survive the
  stomach acidic PH colonize small intestine.

• Salmonella then attach to penetrate the gut
  mucosa resulting in diarrhea from direct mucosal
  damage by action of exotoxins.

• Another portal of entry is invasion of lymphoid
  tissue in the GIT (peyer patches)
  multiplication within macrophages leading to
  bacteremia.

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SALMONELLOSIS

• Salmonella typically produces 3 distinct
  syndromes food poisoning, typhoid fever
  asymptomatic carrier state.

• Salmonella gastroenteritis manifest as vomiting
  diarrhea within 6-48 hours after ingestion of
  food or drink contaminated with bacteria.

• It is self-limiting, treatment is by water
  salts replacement. Antibiotics are not usually
  needed.

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MORTALITY MORBIDITY

• Infection with nontyphoidal salmonella produces
  self-limiting gastroenteritis and food poisoning.

• Whereas mortality caused by typhoid fever is
  rare in western countries, it is associated with
  significant mortality morbidity in tropical
  countries (10-30).

• Dehydration is the most common complication of
  typhoid fever, but serious intestinal
  extra-intestinal complications may occur.

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TYPHOID FEVER

• Typhoid fever is the most serious salmonella
  infection with significant morbidity mortality.

• Caused by salmonella typhi paratyphi.

• Incubation period is 1-2 weeks.

• Salmonella has somatic (O antigen) flagellar H
  antigen. The O antigen is more specific for
  serologic testing.

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FREQUENCY

• An estimated 15-30 million cases of typhoid
  fever occur globally each year.

• The disease is endemic in many developing
  countries in Asia, Central America Africa.

• Outbreak of typhoid fever have been reported
  recently from Eastern Europe.

• Incidence in Sudan is not exactly known, but
  estimated as 50 per 100,000 people/year.

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PRECIPITATING FACTORS

• Defects in cellular-mediated immunity (AIDS,
  Transplant patients malignancy).

• Defects in phagocytic function (malaria,
  histoplasmosis schistosomiasis).

• Splenectomy or functional asplenia (sickle cell
  dis)

• Low stomach PH ( patients on anti-ulcer drug).

• Prolonged use of antibiotics (altered gut flora).

• Injured gut barrier (bowel disease or surgery).

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DIFFERENTIAL DIAGNOSES

• Cryptosporidiosis

• Campylobacter infection

• Cyclospora

• Listeria monocytogenes

• Escherichia Coli infection

• Shigellosis

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LAB FINDINGS

• Salmonella can be grown from blood or bone
  marrow in the 1st week, from stool in the 2nd
  week from urine in the 3rd week.

• Special media are needed for transport for
  culture.

• leukopenia is typical but WBC may be normal.

• Widal test is not diagnostic, titer gt 1320 or 4
  fold increase in titer support the diagnosis.

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CLINICAL PICTURE

• Symptoms begin with sudden onset of high-grade
  fever, headache dry cough.

• Fever is swinging or may show step ladder
  pattern patient initially feel well mobile.

• Abdominal pain toxicity follow soon by the
  end of 1st week spleen is palpable pink,
  discrete, skin rash appears over the trunk.

• Constipation is more common than diarrhea which
  is usually greenish in color (pea soup).

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CLINICAL PICTURE/2

• Abdominal tenderness hepatomegaly occur in 50
  of patients.

• The pulse is relatively slow in relation to
  fever (Paget sign).

• The tongue is coated with free margins
  halitosis may be present.

• The sweat of some patients smell like yeast.

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CLINICAL PICTURE/3

• The 3rd week of illness is the usual time for
  complications in the untreated patients.

• Local gut as well as systemic complications may
  occur.

• Serious infections may progress rapidly to
  drowsiness coma which is usually fatal (coma
  vigil).

• Mortality is unlikely after the 4th week
  patients may become carrier if not treated.

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LOCAL COMPLICATIONS

• Intestinal hemorrhage

• Intestinal perforation

• Paralytic ileus

• Zenker degeneration of abdominal muscles

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SYSTEMIC COMPLICATIONS

• Endocarditis

• Arteritis arterial emboli

• Cholecystitis

• Hepatic splenic abscesses

• Pneumonia or empyema

• Osteomyelitis septic arthritis

• Meningitis

• Urinary tract infection

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TREATMENT

• Medical care include rehydration, antipyretics
  antibiotics.

• Drugs of choice are Ceftriaxone ciprofloxacin
  but Cotrimoxazole Chloramphenicol are still
  used in developing countries. Ampicillin kills
  bacilli hiding in the bile hence prevents or
  reduce the carrier state.

• Chronic resistant carrier state may necessitate
  cholecystectomy. Surgical care may also be needed
  in patients with intestinal complications.

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NURSING CARE

• Isolation barrier nursing is indicated

• Notification of the case to the infection
  control nurse in the hospital.

• Trace source of infection.

• continue breastfeeding infants young children
  and give ORS light diet for other patients in
  the first 48 hours.

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PREVENTION

• Education on hygiene practices like hand washing
  after toilet use avoidance of eating in non
  hygienic restaurants.

• Proper handling refrigeration of food even
  after cooking.

• Salmonella TAB vaccine is available but
  affectivity is low (50 claimed protection).

• Antibiotic prophylaxis is not needed for
  house-hold contacts.

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PROGNOSIS

• With early diagnosis and prompt treatment most
  patients with typhoid fever will recover in due
  time.

• Fever toxicity subsides within 72 hours of
  antibiotic treatment.

• Mortality is gt 50 in untreated severe typhoid
  fever particularly in children elderly.

• Recrudescence is rare but chronic carrier state
  is reported in 10 of patients.