Gastroenteritis%20-%20bacterial Diagnosis

• Initial clinical evaluation of the patient with acute diarrhea should focus on assessment of the severity of the illness, the need for rehydration and the identification of likely causes on the basis of history and clinical findings
• A careful clinical evaluation is needed in order to provide a cost-effective evidence-based approach to initial diagnostic tests and treatment
• Management of acute diarrhea may be decided upon the history and presentation

Toxin-Induced Food Poisoning

• Should be suspected in those with vomiting as the major presenting symptom

Bacterial Toxin-Induced Food Poisoning

• Incubation period varies depending on causative agent
• Diarrhea may follow vomiting and is usually not so severe
• Abdominal pain may also be present and is usually colicky in nature
• Most patients are afebrile and not severely dehydrated unless vomiting or diarrhea is intense

Traveler’s Diarrhea

• Usually considered in a person who normally resides in an industrialized region and who travels to developing/underdeveloped countries
• May also refer to illness that occurs within 7-10 days after returning home
• Patient often feels weak and with orthostatic symptoms

• Types of diarrhea by duration includes acute and chronic diarrhea
  • Acute diarrhea is diarrhea lasting for ≤14 days duration
  • Chronic diarrhea is diarrhea lasting for >14 days

Goals

• To provide a starting point for treatment
• To segregate which patients can safely be sent home for therapy, which ones should remain for observation during therapy and which ones immediately need intensive therapy
  • Consider admitting patient to the hospital if with severe dehydration, failed rehydration, serious alternative diagnoses, or concerns regarding caregiver’s ability to administer rehydration therapy or to identify significant symptoms requiring a return visit 

Dehydration Assessment 

Minimal or No Dehydration

• Consists of <3% loss of body weight (<5% in infants)
• Normal heart rate (HR), respiratory rate (RR) and pulse volume
• Normal eyes with presence of tears, moist mucous membranes
• Normal capillary refill
• Normal to decreased urine output
• Patient is well and alert

Mild to Moderate Dehydration

• Consists of 6% loss of body weight (5-10% in infants)
• Normal to increased heart rate, respiratory rate
• Normal to decreased pulse volume
• Slightly sunken eyes with decreased tears, sticky mucous membranes
• Delayed capillary refill
• Decreased urine output
• Patient may appear normal, listless or fatigued

Severe Dehydration

• Consists of >9% loss of body weight (>10% in infants)
• Tachycardia with bradycardia especially in severe cases, deep respiration
• Thready to absent pulse
• Deeply sunken eyes with absence of tears, parched mucous membranes
• Poor capillary refill
• Minimal urine output
• Patient may appear lethargic to comatose

• Determine abrupt or gradual onset, duration and progression of symptoms
• Onset and frequency of bowel movement
• Amount of stool excreted
• If dysenteric symptoms are present (eg fever, tenesmus, blood/pus in stool)

• Vital Signs
  • Orthostatic pulse, blood pressure (BP) changes, rate of breathing, presence of fever
• Other signs of volume depletion
  • Dry mucous membranes, decrease in skin turgor
• Abdominal tenderness
• Altered sensorium
• Accurate body weight to estimate fluid loss
• Other findings may include excessive irritability, cyanosis, petechial rash 

• The majority of patients presenting with acute gastroenteritis do not require laboratory tests
• Consider complete blood count (CBC), blood culture, fecalysis, stool culture and sensitivity, molecular testing [eg polymerase chain reaction (PCR)], serum electrolytes, (ie sodium, bicarbonate, potassium), urinalysis, blood urea nitrogen (BUN), and creatinine in patients with evidence of systemic illness, fever, bloody stools and moderate to severe dehydration
  • Presence of white and red blood cells on direct microscopy of stool is diagnostic of Shigella
• If considering to give IV rehydration, electrolytes, glucose and creatinine should be ordered 
• Further stool studies are indicated when patient has a history of traveling abroad, or diarrhea that does not improve within 7 days or that occurred in a gastroenteritis outbreak
• Stool Exam: Stools typical of cholera are typically greenish-yellow, clear, watery and with little food residue (rice-watery stools)
  • If cholera is confirmed in nonendemic areas, it should be reported to health authorities
• Stool Microscopy:
  • May reveal bacteria with darting motility
  • No white blood cell (WBC) or red blood cell (RBC)
  • Cholera: Microscopic exam of stool may also reveal shooting bacteria, but not white blood cell (WBC) or red blood cell (RBC)
• Dark field microscopy (DFM) and Stool Culture/Sensitivity: Should be performed in both non-endemic and endemic areas
  • Cholera: Dark-field microscopy (DFM) and stool culture should be done in all cases