Vibrio

• Cholera is one of the oldest diseases with pandemic potential

  
• The world has experienced seven cholera pandemics in the last 194 years

  
• The first cholera pandemic occurred, largely originating in Jessore, India


  1817 and 1923

  
• The epidemic continued and eventually reached other continents including Europe and the Americas
• The seventh pandemic began in the Celebes Islands, Indonesia, with spread to Asia, the Middle East, and Africa and continues today


  1961
• In the Philippines, the last case of cholera of the pandemic which commenced March 20, 1902, was reported to have occurred March 8, 1904. During that period 166,252 cases, with 109,461 deaths, were reported

  
• In 2019, the Department of Health (DOH) reported a 211% increase of reported cholera cases from 918 in 2018 to 2,856 cases in 2019

  
• Gram-negative curved or comma-shaped bacilli


  • Motile (polar, monotrichous flagellum), EXCEPT Vibrio metschnikovii; they exhibit "darting: or "shooting star" motility
  • Non-spore-forming
  • Facultative anaerobic
  • Aquatic organisms that are found in fresh water, brackish or estuarine water, and marine or salt water
  • Grow in alkaline media
  • Most are halotolerant, some are halophilic
  • Glucose fermentation
  • Catalase(+), EXCEPT Vibrio metschnikovii
  • Oxidase(+), EXCEPT Vibrio metschnikovii
• Kommabacillus


  Common name for V. cholerae because of the characteristic curved or comma-shaped appearance of the individual bacterial cells
• Man is the only known reservoir of V. cholerae
• Human carriage may persist after untreated infection for months after infection; however, permanent carrier state is rare
• They can survive and grow in fresh and brackish water
• Transmission


  By fecal-oral route. The most common source of infection is contaminated water. Food, especially shellfish (contaminated from contaminated waters) eaten raw, have also been a source of infection
• Cholera


  Also known as Asiatic cholera or epidemic cholera
• Incubation period


  12 hours up to 3 days depending on the size of the inoculum ingested
• Symptoms


  • Sudden onset of nausea, vomiting, abdominal cramps and profuse "rice water" diarrhea (stool resembles water in which the rice has been boiled) that may be as many as 10 to 30 per day, containing mucus, epithelial cells, and large numbers of vibrios
• Severe cholera


  Infected individual can lose several liters of fluid, as much as 20-30 liters per day. If left untreated, it can result in a rapid fluid and electrolyte loss that leads to dehydration, hypovolemic shock, metabolic acidosis, and death in a matter of hours
• Virulence factors


  • Motility and mucinase to aid in penetration of the protective mucin layer
  • Choleragen (cholera toxin) which activates adenylate cyclase, causing increased levels of cyclic adenosine monophosphate (cAMP) and hypersecretion of electrolytes (Na+, K+, HCO3−) and water out of the cell and into the lumen of the intestine
• V. cholerae are sensitive to gastric acid, thus require high infectious dose if the stomach acid is normal. An estimated 1010 organisms per milliliter are required to survive gastric passage in healthy persons; only about 100 organisms per milliliter are required in hypochlorhydric persons, either because of previous gastrectomy or from ingestion of antacids in treatment of gastric ulcer disease
• H antigen (or flagellar antigen)


  Heat-labile substances that are found in all V. cholerae strains
• O antigen (or somatic antigen)


  Cell wall lipopolysaccharides that confer serologic specificity to the bacterial cells and form the basis of a serotyping scheme that classifies the 139 strains of V. cholerae, designated from O1 to O139
• Serogroups of V. cholerae


  • V. cholerae O1
  • V. cholerae non-O1
  • V. cholerae O139
• V. cholerae O1


  Is agglutinated by V. cholerae O1 antiserum, includes virulent strains producing cholera toxin, associated with epidemic cholera
• V. cholerae non-O1


  Is NOT agglutinated by V. cholerae O1 antiserum, includes V. cholerae O2 up to V. cholerae O138, does NOT produce cholera toxin but appears to produce an enterotoxin different from cholera toxin, has been associated with isolated cases of diarrheal disease (NOT epidemic-associated)
• V. cholerae O139


  Is NOT agglutinated by V. cholerae O1 antiserum, represented a new serogroup, produces cholera toxin in quantities similar to that produced by V. cholerae O1, makes polysaccharide capsule like other non-O1 strains, has spread in epidemic proportions across the Indian subcontinent

  
• Biotypes of V. cholerae O1


  • Classical strain
  • El Tor strain
• Classical strain of V. cholerae

  Caused the epidemic cholera from early 1800s to early 1900 during which there were 6 waves of cholera pandemic that spread across the world

  
• El Tor strain of V. cholerae


  Isolated in the early 1900s from Mecca-bound pilgrims at the El Tor Quarantine Station in Sinai Peninsula, found to be hardier and better capable of surviving in the environment, associated with the epidemic in the Philippines in 1961 that has started the 7th pandemic, currently the predominant cholera pathogen

  
• Serotypes of V. cholerae O1


  • Ogawa
  • Inaba
  • Hikojima
• Ogawa and Inaba strains


  Considered the predominant epidemic strains
• Hikojima strain


  Has been isolated in outbreaks, but its occurrence has been rare
• Control rests on education and on improvement of sanitation, particularly of food and water
• Patients should be isolated, their excreta disinfected, and contacts followed up
• Repeated injection of a vaccine containing either lipopolysaccharides extracted from vibrios or dense Vibrio suspensions can confer limited protection to heavily exposed persons (eg, family contacts) but is not effective as an epidemic control measure
• Specimens


  Feces is the preferred specimen, collected and transported in Cary-Blair medium. Rectal swabs are also acceptable
• Microscopy


  • Gram-negative curved or comma-shaped bacilli, 2–4 µm long. On prolonged cultivation, vibrios may become straight rods that resemble the Gram-negative enteric bacteria
• Alkaline Peptone Water (APW)


  Enrichment medium that promotes the growth of Vibrio species while inhibiting most of the commensal intestinal bacteria
• 5% Sheep BAM


  Nonselective medium for culturing Vibrio species
• APW


  Alkaline peptone water
• APW


  • 1% (w/v) sodium chloride promotes the growth of Vibrio species
  • Alkalinity (pH 8.6) inhibits most of the commensal intestinal bacteria