Acinetobacter radioresistensis a rare cause of nosocomial infection and is believed to confer antibiotic resistance to aggressive bacterial species. We present the first reported case of polymicrobial endocarditis caused byA. radioresistensandMicrobacterium paraoxydansco-infection, a case of a woman in her late 60s with bacteraemia and ultimate finding of endometrial carcinoma. Bacteraemia with either agent in a previously healthy patient should prompt providers to search for underlying malignancy or immunological problem.We support the use of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry for identifying these organisms in cultures, as well as the development of faster isolation techniques through PCR. Furthermore, we advocate for providers to order early antibiotic susceptibility testing, since our patient’sMicrobacteriumsp was not susceptible to meropenem unlike mostMicrobacteriumreported in literature.