Question

a 52-year-old man who had recently received a kidney transplant was admitted to the hospital with a low-grade fever, a heart murmur, and neutropenia. he had a history of periodontal disease and recently had two teeth extracted. blood cultures were positive after 48 hours. the isolate grew on choc agar and sba in 5% co2. the colonies were nonhemolytic, slightly adhered to the surface of the media, and had a slight yellow appearance when removed. the isolate was catalase-, indole-, and oxidase negative. microscopic morphology indicated gram-negative fusiform bacilli. the most probable identification is:

Answer 1

The patient is most likely infected with Capnocytophaga spp., considering their clinical history and the laboratory findings including growth on chocolate agar and negative catalase, indole, and oxidase tests.

Step-by-step explanation:

The most probable identification of the pathogen based on the clinical presentation and laboratory results is Capnocytophaga spp., specifically Capnocytophaga ochracea. This identification is grounded on the patient's recent history of dental procedures, nonhemolytic colonies with a slight yellow appearance that grew on chocolate agar (CHOC) and sheep's blood agar (SBA) in 5% CO2, and other test results such as being catalase-, indole-, and oxidase-negative. Given the patient's immunocompromised state due to the recent kidney transplant, the history of periodontal disease, and recent dental extractions, Capnocytophaga spp. can cause opportunistic infections leading to symptoms such as fever, heart murmurs, and neutropenia indicative of a bacterial infection.