entero part 2

• Citrobacter


  Genus of bacteria
• Citrobacter species


  • 12 species
• Citrobacter


  • Normal gastrointestinal flora
  • Most common species: C. freundii, C. koseri, and C. braakii
• Citrobacter transmission


  • Person-to-person
  • Nosocomial
• Citrobacter virulence factors


  • Endotoxin
  • Capsule
  • Adhesion proteins
  • AmpC genes (for C. freundii, resistance to ampicillin and 1st Gen cephalosporins)
• C. freundii


  • More of an extraintestinal pathogen
  • Can cause endocarditis in IV drug abuser
• C. koseri


  • Can cause nursery outbreaks of neonatal meningitis and brain abscess
• C. braakii


  • Rare human pathogen associated with community-acquired infections including septicemia in a patient with cervical cancer
• Citrobacter freundii resembles Salmonella because 80% produce hydrogen sulfide and 50% fail to ferment lactose
• Laboratory diagnosis of Citrobacter


  • Hydrolyze urea slowly
  • Late lactose fermenter (CHYSSS)
  • All species grow on Simmons citrate medium
  • Methyl red: positive
  • Resembles Salmonella
• Cronobacter


  (formerly Enterobacter)
• Cronobacter species


  • 7 species
• Cronobacter habitat


  • Normal gastrointestinal flora
  • Powdered infant formula (since di agad natutuyo)
• Cronobacter transmission


  • Person-to-person
  • Ingestion
• Cronobacter virulence factors


  • AmpC chromosomal betalactamase - resistance to ampicillin, and 1G and 2G cephalosporins (mutation shall result to overproduction of beta lactamase leading to resistance to 3G cephalosphorin)
• C. sakazaki


  • Can cause neonatal infection such as bacteremia, meningitis and necrotizing colitis
• C. maloniticus


  • Can cause adult infection
• Edwardsiella


  Genus of bacteria
• Edwardsiella species

  • 3 species; H: 1 only
• Edwardsiella habitat


  • Water harboring fish and turtles
  • Commonly cold- and warm-blooded animals
• Edwardsiella transmission


  • Endogenous
  • Nosocomial
• E. tarda


  • Rarely encountered unless immunocompromised
  • Can cause wound infection called myonecrosis, gastroenteritis, septicemia, meningitis, and systemic infection if with underlying liver disease
• E. hoshinae


  • Found in snakes, birds, and water
• E. ictaluri


  • Causes enteric septicemia in fish
• Myonecrosis


  Also called infarction of skeletal muscle, occurs when the blood supply is inadequate to maintain muscle viability
• Edwardsiella laboratory diagnosis


  • Culture: MAC - clear and colorless
  • Biochemical test: Urease (-), LDC (+), H2S (+) - black PECS, Indole (+) - Mor PECPEK Ples
• Enterobacter


  Genus of bacteria
• Enterobacter species


  • 12 species
• Enterobacter habitat


  • Normal gastrointestinal flora, water, food and vegetables (common in farmers)
• Enterobacter transmission


  • Endogenous
  • Nosocomial
• Enterobacter virulence factors


  • Endotoxin
  • Capsule
  • Adhesion proteins
  • Plasmids - resistance to multiple antimicrobial agents
• E. cloacae

  • Most commonly isolated
  • Causes UTI, respiratory tract and wound infections
  • Listed in the top 10 commonly isolated healthcare-associated infections
• Enterobacter laboratory diagnosis


  • Motile
  • Rapid lactose fermenter
  • Produces mucoid colony
  • Urease (-) except E. gervoiae
• Escherichia coli


  Genus of bacteria
• E. coli species


  • 6 species
• E. coli habitats


  • Diarrheagenic or intestinal: STEC, ETEC, EPEC, EIEC, EAEC
  • Extraintestinal: UPEC, MNEC
  • 80% have K1 antigen
• E. coli transmission


  • Fecal-oral route or consumption of undercooked beef or milk from colonized cattle (depending on strain)
  • Endogenous
• Escherichia coli is the leading cause of UTI, along with Staphylococcus saprophyticus
• E. coli is used as an indicator of fecal contamination of water
• UPEC virulence factors


  • Pili: for adherence to cells
  • Cytolysins: inhibit immune effector cells
  • Aerobactin: chelate iron
  • Capsule production