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
Rarehuman 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 10commonly 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