Salmonella typhi

Snapshot

• A 4-year-old girl presents to her pediatrician for diarrhea and fever. She recently flew back from India, where she spent a summer with her grandparents. She has had a low-grade fever since 3 days prior and had constipation followed by non-bloody diarrhea. On physical exam, she has a low grade fever, abdominal tenderness to palpation, and a faint pink macular rash on her trunk and upper arms. She is started on antibiotics.

Introduction

• Classification 
  • Salmonella typhi
    • a flagellated, non-lactose fermenting, gram – rod
    • a endotoxin-producing bacteria
  • transmission
    • fecal-oral route 
• Epidemiology
  • incidence
    • high in places of poor sanitation
    • India, China, Southeast Asia, and Africa
  • demographics
    • travelers
    • children
  • risk factors
    • travel to endemic area
• Pathogenesis
  • inactivated by gastric acids, so a large inoculum is required
  • crosses intestinal epithelium track through invasion of Peyer patches M cells
  • the bacteria then spread via lymphatics and bloodstream
    • may colonize the gallbladder in chronic carriers 
• Associated conditions
  • typhoid fever
  • osteomyelitis
    • most common cause in sickle cell patients
• Prevention
  • vaccines are recommended prior to traveling to endemic areas
  • oral live-attenuated vaccine
    • 6 years of age or older
  • parenteral vaccine containing Vi capsular polysaccharide
• 2 years of age or older

Presentation

• Symptoms 
  • fever lasting several days
  • constipation initially
  • non-bloody diarrhea later
  • abdominal pain
  • malaise
  • anorexia
• Physical exam
  • fever
  • relative bradycardia
  • pink macular rash that spreads from trunk to extremities
    • rose spots  
  • abdominal tenderness
  • hepatosplenomegaly
• signs of dehydration

Studies

• Labs 
  • culture of blood or stool
• Making the diagnosis
• based on clinical presentation and laboratory studies

Differential

• Shigella infection
  • distinguishing factor
• bloody diarrhea

Treatment

• Management approach
  • antibiotics can increase the duration of gastrointestinal symptoms but are still recommended to prevent complications and relapse
  • choice of antibiotics should be guided by local resistance patterns
• Conservative
  • supportive care
    • indication
      • all patients
    • modalities
      • rehydration
      • correction of any electrolyte imbalances
• Medical
  • fluoroquinolones 
    • indication
      • first-line for all patients
    • drugs
      • ciprofloxacin
      • ofloxacin
  • azithromycin          
    • indication
• resistance or intolerance of fluoroquinolones

Complications

• Intestinal perforation
  • cause of mortality