Ignatzschineria larvae bacteriemia in an intensive care unit patient: a case report and a review of the literature

Background Ignatzschineria larvae is a Gram-negative bacterium found in the microbiota of several fly species but rarely involved in human pathology. Case presentation We report the case of a patient admitted to the intensive care unit for sepsis with a bloodstream infection due to Ignatzschineria larvae and methicillin-susceptible Staphylococcus aureus secondary to a scalp wound infestation by Calliphora vomitaria . Morphological examination allowed identification of the larva, bacterial culture and molecular biology techniques identified the bacteria and its antibiotic susceptibility and resistance. An unusual resistance profile, including fluoroquinolones, fosfomycin and cyclines, was observed. NGS identified the underlying genetic determinant. The patient was successfully treated with cefotaxime and daptomycin then trimethoprim-sulfamethoxazole and oxacillin. Discussion Only eight Ignatzschineria larvae infections in humans had been previously reported, always from a skin barrier alteration in patients with poor social conditions and often associated with chronic alcohol consumption. Although most strains described in the literature are susceptible to beta-lactam antibiotics, our clinical case provides additional documentation necessary for optimizing the management of this type of infection.