Case Presentation: Ms. M is an 80 yo female with DM 2, COPD and gout, initially admitted to a tertiary care medical center in 2019 for sepsis of presumed urinary origin. She was treated with ceftriaxone and rapidly improved. Her urine culture and blood cultures from admission remained negative on hospital day 3, so she was discharged home on empiric ciprofloxacin. However, one day post discharge, 2/4 blood cultures returned positive for gram negative rods. She was readmitted and restarted on ceftriaxone. Blood cultures eventually speciated to Capnocytophaga, and questioning revealed the patient owned a cat and dog. She sustained a cat scratch and bite on her left forearm two weeks prior to her initial admission, and her dog licked wounds on her legs, sustained while doing yardwork, one week prior to admission. An Infectious Disease consult was obtained when Capnocytophaga was identified. Her antibiotic regimen was changed to piperacillin/tazobactam and she was observed for another day, prior to discharge home, to complete a two-week course of parenteral therapy.
Discussion: Capnocytophaga infections are primarily found in patients recently exposed to cat and dog saliva in an open wound, and can result in severe complications, including sepsis, septic shock, soft tissue infections and meningitis. The case fatality rate averages thirty percent, with mortality rates high even among patients who are immunocompetent. (van Dam, 2011) Patients at increased risk for severe illness include those who are immunocompromised, those with asplenia or functional splenia and those with cirrhosis or a history of excessive alcohol use. The diagnosis is established by culture, but organism growth is slow. Blood cultures turn positive at a mean of six days and colonies on plates take two to four days to reach adequate size for analysis. (Kullberg, 1991) Many hospitals do not do sensitivity testing. Once identified, severe infections should be treated with a beta-lactam-beta-lactamase combination or a carbapenem. No studies have examined optimal duration of treatment. (Goldberg, 2020) Patients with less severe infections may be treated with oral therapy such a amoxicillin-clavulanate or clindamycin.
Conclusions: 1. Capnocytophaga infections should be considered in the differential of patients exposed to cat and dog saliva in open wounds.2. Patients who are asplenic, alcoholic, immunocompromised, or have cirrhosis are at increased risk for severe infections. 3. Blood cultures turn positive at a mean of six days and colonies can take up to four days to reach adequate size for analysis. 4. Piperacillin-tazobactam can be used to treat, based on common sensitivity patterns. Alternative regimens include a carbapenem. Amoxicillin-clavulanate or clindamycin can be used for mild infections. 5. No studies have examined optimal duration of therapy.