Sepsis in a renal transplant recipient due to Citrobacter braakii

Cellulitis is usually caused by organisms such as beta-hemolytic streptococci and Staphylococcus aureus. Citrobacter are gram-negative bacilli that can cause opportunistic infections in immunocompromised hosts. They are rarely implicated in skin or soft tissue infections. The genus Citrobacter has been respeciated according to genetic relatedness. Citrobacter braakii refers to the genomospecies 6 of the Citrobacter freundii complex. There are no detailed studies of infections caused by the newly formed specific genetic species. We report a case of C. braakii infection in a renal transplant patient receiving immunosuppressive therapy. The patient's lower extremity cellulitis did not respond to conventional antibiotic therapy. Blood cultures grew C. braakii. Sensitivity studies and treatment with appropriate antibiotics resulted in prompt recovery. Immunosuppressive therapy in renal transplant recipients predisposes to infection by unusual pathogens, and this should be suspected when lack of a clinical response to conventional antibiotics is observed. We believe this is the first reported case of C. braakii cellulitis and bacteremia in a renal transplant recipient.