Invasive CSP-1-Capnocytophaga gingivalis in a 60 year-old female with severe neutropenia.

The human-oral associated Capnocytophaga species are low-grade pathogens, more commonly affecting immunocompromised patients. Bloodstream infections are the most common clinical presentation. Microbiological diagnosis and antibiotic susceptibility testing are challenging due to the hard-to-growth character of these species, which complicates the initiation of effective antibiotic therapy. We present the case of an immunocompromised 60-year-old female receiving cefepime who developed febrile neutropenia. Blood cultures remained positive for a Capnocytophaga gingivalis isolate producing the CSP-1 extended-spectrum-β-lactamase (ESBL). This is the first description of CSP-1 in a non-C. sputigena species. Immune reconstitution led to clinical resolution.