Citrobacter spp

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Citrobacter freundii growth on agar

Citrobacter spp are Gram-negative enteric coliform bacteria associated with cystitis in the dog and cat[1].

These bacteria are enterobacteria commonly isolated from soil, water, sewage, and food and are considered to be an opportunistic or secondary pathogen of the skin, and gastrointestinal and respiratory tracts[2]. In dogs, they are part of the normal biotome of the oropharynx[3] and gastrointestinal flora.

Species which are pathogenic to dogs include:

  • Citrobacter freundii
  • Citrobacter diversus
  • Citrobacter koserii

In humans, this bacteria has been reported as causing sepsis and meningitis in neonates[4][5].

In dogs, Citrobacter spp are commonly involved in recurrent cystitis, with reports of emphysematous cystitis occurring rarely[6]. Localized infections associated with indwelling intravenous catheters[7] are common, and secondary infections with respiratory ailments are noted[8].

However, septicemia is not uncommon, with a number of puppies and immunocompromised adult dogs reportedly suffering acute hemorrhagic diarrhea, followed by septicemia, peritonitis[9], myocarditis[10] and fibrinous pericarditis[11].

Antimicrobial therapy is advised, using drugs such as amoxycillin/clavulanate or cephalosporins[12] such as cefovecin, based on culture and sensitivity studies. Resistance to fluoroquinolones has been reported[13].


  1. Euclid, JM et al (2011) Case Study: Citrobacter vaginitis and salpingitis in a Burmese kitten. Online J Vet Res 15(4):420-423
  2. Farmer, JJ & Kelly, MT (1991) Enterobacteriaceae, p.360-383. In A. Balows, et al (Eds): Manual of clinical microbiology, 5th ed. American Society for Microbiology, Washington, D.C.
  3. Kasempimolporn S et al (2003) Oral bacterial flora of dogs with and without rabies: a preliminary study in Thailand. J Med Assoc Thai 86(12):1162-1166
  4. Eppes SC et al (1993) Recurring ventriculitis due to Citrobacter diversus: clinical and bacteriologic analysis. Clin Infect Dis 17(3):437–440
  5. Tse G et al (1997) Neonatal meningitis and multiple brain abscesses due to Citrobacter diversus. Pediatr Pathol Lab Med 17(6):977–982
  6. Chang J et al (2007) What is your diagnosis? Emphysematous pyometra with a large amount of gas. J Small Anim Pract 48(12):717-719
  7. Lobetti RG et al (2002) Bacterial colonization of intravenous catheters in young dogs suspected to have parvoviral enteritis. J Am Vet Med Assoc 220(9):1321-1324
  8. Johnson LR & Fales WH (2001) Clinical and microbiologic findings in dogs with bronchoscopically diagnosed tracheal collapse: 37 cases (1990-1995). J Am Vet Med Assoc 219(9):1247-1250
  9. Galarneau JR et al (2003) Citrobacter freundii septicemia in two dogs. J Vet Diagn Invest 15(3):297-299
  10. Cassidy JP et al (2002) Myocarditis in sibling boxer puppies associated with Citrobacter koseri infection. Vet Pathol 39(3):393-395
  11. Stafford Johnson JM et al (2003) Septic fibrinous pericarditis in a cocker spaniel. J Small Anim Pract 44(3):117-120
  12. Limbert M et al (1991) Antibacterial activities in vitro and in vivo and pharmacokinetics of cefquinome (HR 111V), a new broad-spectrum cephalosporin. Antimicrob Agents Chemother 35(1):14-19
  13. Ewers C et al (2011) Companion animals: a relevant source of extended-spectrum β-lactamase-producing fluoroquinolone-resistant Citrobacter freundii. Int J Antimicrob Agents 37(1):86-87