Vibrio

Characteristics Gram-negative, highly motile curved rods, polar flagella Oxidase-positive Facultative anaerobic Tolerant to alkali but not to acid

Pathogens of humans V. cholerae V. parahaemolyticus

Vibrio cholerae

Biological characteristics Structure and shape Gram-negative curved rods a single, polar flagellum Culture in the absence of salt at a high pH (8.5-9.5) TCBS (thiosulfate-citrate-bile-sucrose)

Biological characteristics Antigenic structure and classification H antigen: non-specific O antigen: 155 serogroups V. Cholerae serogroups O1 V. Cholerae serogroups O139 V. Cholerae serogroups non-O1/non-O139

Biological characteristics Antigenic strcture and classification 2 biotypes (O1): classic biotype El Tor biotype 3 serotypes (O1): Ogawa（AB） Inaba（AC） Hikojima（ABC）

History Epidemic: a disease occurring in an unusually high number of individuals in a population at the same time. Pandemic: a worldwide epidemic. Endemic: a disease that always presents in low members in a particular community Sporadic: a disease that occurs occasionally, usually affecting one person. 7 pandemics (since 1817) the former 6 pandemics → classical strains (O1) the latter 1 pandemic → El Tor strains (O1): began in 1961 in Asia. a recent epidemic (in 1992 in India) → V. Cholerae O139→ cholera-like symptoms.

Pathogenicity Virulence factors Vibrio cholerae enterotoxin Flagellum pili（toxin-coregulated pilus A, tcpA） other toxic factors: hlyA, hap capsule: O139

Mode of enterotoxin a protein composed of A and B subunits. B subunits (binding sites) → binding to receptors of epithelial cells A subunit (toxic site) → activating adenyl cyclase ↓ ATP → cAMP changing ion transport mechanisms extensive secretion of fluids and electrolytes ie. Na+, Cl-, K+, HCO3- severe vomiting and diarrhea

Pathogenicity Disease: Cholera human is the only host Source of infection : (O1,O139) ingestion of the contaminated food and water 1010 bacteria → mouth → stomach → small intestine → enterotoxin

Pathogenicity Incubation period: 2-3 days. Manifestation: severe vomiting, rice-water diarrhea, and dehydration. Death rate: renal failure, metabolic acidosis, shock. non-O1 strains: symptoms similar to those of O1 strains, but less severe; often sporadic not pandemic or epidemic.

Immunity HI Permanent SIgA antibodies vibriocidal antibodies antitoxin antibodies Permanent

Control Prevention Treatment improvement of sanitation vaccine: limited or no effective Treatment water and electrolyte replacement antimicrobial agents

V.parahaemolyticus

Characteristics a marine vibrio culture - grow best under high salt concentration condition.

Pathogenicity Virulence factor hemolysins hemolyze the human and rabbit erythrocytes -kanagawa test 神奈川现象: differentiates pathogenic strains from non-pathogenic strains

Pathogenicity Disease Gastroenteritis (food poisoning) Transmission ingestion of potential contaminated seafood Manifestations watery diarrhea, abdominal cramps, nausea, and vomiting.

Treatment in mild infections self-limited disease in severe infections antibiotics, fluid and electrolytes replacement