VIBRIONACEAE :
• Curved to comma shaped
• Polarly flagellated
• Facultative anaerobes
o Aerobic & therefore catalase & oxidase +ve (similar to aerobic Pseudomonads)
o Fermenters ie anaerobic
• Widespread distribution (fresh water, sea water) & human & animal intestinal tracts); not indicators of fecal pollution.
• 3 genera (Vibrio, Aeromonas, Photobacterium)
o Vibrio Cholera (aka Asiatic cholera)
Two biotypes of serogroup O:1 known (classic cholera & Eltor [Mecca camp]); Eltor endemic in coastal regions eg India, Bangladesh & South America; USA non-O1 serogroup due to consumption of contaminated seafood.
Transmitted thro' sewage contaminated water & food; rice water stools
Multiplies in intestinal epithelial cells (but not invasive to other tissues) & produces an enterotoxin (binds irreversibly to epithelial cells stimulating the production of cyclic which changes cell permeability leading to the secretion of water & electrolytes into the lumen. 12 to 20 litres of water lost-- dehydration; replacement of electrolytes & water necessary is the best treatment; Tetracycline decreases disease period; vaccines provide short immunity but natural infections provide a longer duration (against enterotoxin & cells)
Culture in alkaline medium (high pH decreases the growth of other bacteria)
Vibrio parahemolyticus
Habitat is salt water and requires > 2% NaCl for growth in laboratory media (halophilic) Gastroenteritis from contaminated shell fish, crabs; USA, Japan, Hawaii Large nos. within 24 hr & recovery follows in a few days.
o Aeromonas
Mainly pathogens of fresh water fish, turtles & frogs.
May be encountered as causative agents of human diseases.
o Photobacterium
Interesting due to the property of bioluminescence (aka luminescent bacteria); ATP + electron transport chain + enzyme luciferase = luminescence
Normal flora of some fish (flash light fish); behavioral activities (mating, protection)
Sunday, April 5, 2009
13 - Facultative anaerobes part 3 ( ENTEROBACTERIACEAE )
• Escherichia :
o Most common inhabitants of intestinal tracts.
o Food & water presence indicates fecal contamination; indicator bacterium
o Endogenous spread (septacemia, urinary tract infections, meningitis) or food-water borne transmission (gastroenteritis, travellers diarrhea)
o Antigenic composition complex: 170, 57 H and several K antigens (epidemiological & specific serotypes associated with increased virulence (H157:O7)
o Septicimia: Focus of infection is urinary tract or intestine and spreads to bloodstream (higher incidence of death in immunocmpromised patients)
o Urinary tract infection: 80% = community aquired or hospital aquired. 10 specific serotypes usually involved (eg 01, 02, 016, 075) & origin is from gastrointestinal tract.
o Pathogenecity --serotypes more adhesive to uroepithelial cells than other serotypes
o Meningitis: E.coli & B streptococci cause 75%. Serotype K1
o Gastroenteritis: 4 groups; enterotoxigenic (ETEC) causes travellers & infant diarrhea, pathogenecity similar to V. cholera toxin ie stimulates hypersecretion of fluids & electrolytes in gastrointestinal tract , not serotype specific, produce heat labile & heat stable plasmid mediated enterotoxins, not serotype specific (NA probing, tissue culture or animal models & not serotyping for identification. Enteroinvasiveness (EIEC)
• Klebsiella :
o Capsulated
o K. pneumoniae-- pneumonia (old or immunocompromised eg alcoholics); also causes septecimia in hospital pediatric wards
• Serratia :
o S. marcesens- red pigmented colonies
o Causes hospital aquired infections (nosocomial) like Enerobacter
o Urinary & respiratory tract infection
o Isolated from sterile saline solution, catheters
• Proteus :
o Extremely motile
o P. mirabilis-- urinary tract infection; produces urease & splits urea to CO2 and NH3 to increase pH & therefore facilitate renal stone formation & uroepithelium toxicity.
o Pili decreases phagocytosis & therefore decreases virulence unlike E. coli .
• Erwinia :
o Plant pathogens (phytopathogens)
o Produce pectinase which hydrolyse pectin between plant cells & cause plants to rot
o Most common inhabitants of intestinal tracts.
o Food & water presence indicates fecal contamination; indicator bacterium
o Endogenous spread (septacemia, urinary tract infections, meningitis) or food-water borne transmission (gastroenteritis, travellers diarrhea)
o Antigenic composition complex: 170, 57 H and several K antigens (epidemiological & specific serotypes associated with increased virulence (H157:O7)
o Septicimia: Focus of infection is urinary tract or intestine and spreads to bloodstream (higher incidence of death in immunocmpromised patients)
o Urinary tract infection: 80% = community aquired or hospital aquired. 10 specific serotypes usually involved (eg 01, 02, 016, 075) & origin is from gastrointestinal tract.
o Pathogenecity --serotypes more adhesive to uroepithelial cells than other serotypes
o Meningitis: E.coli & B streptococci cause 75%. Serotype K1
o Gastroenteritis: 4 groups; enterotoxigenic (ETEC) causes travellers & infant diarrhea, pathogenecity similar to V. cholera toxin ie stimulates hypersecretion of fluids & electrolytes in gastrointestinal tract , not serotype specific, produce heat labile & heat stable plasmid mediated enterotoxins, not serotype specific (NA probing, tissue culture or animal models & not serotyping for identification. Enteroinvasiveness (EIEC)
• Klebsiella :
o Capsulated
o K. pneumoniae-- pneumonia (old or immunocompromised eg alcoholics); also causes septecimia in hospital pediatric wards
• Serratia :
o S. marcesens- red pigmented colonies
o Causes hospital aquired infections (nosocomial) like Enerobacter
o Urinary & respiratory tract infection
o Isolated from sterile saline solution, catheters
• Proteus :
o Extremely motile
o P. mirabilis-- urinary tract infection; produces urease & splits urea to CO2 and NH3 to increase pH & therefore facilitate renal stone formation & uroepithelium toxicity.
o Pili decreases phagocytosis & therefore decreases virulence unlike E. coli .
• Erwinia :
o Plant pathogens (phytopathogens)
o Produce pectinase which hydrolyse pectin between plant cells & cause plants to rot
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