Polymicrobial bacteremia including Ignatzschineria indica caused by myiasis in a female patient with carcinoma of unknown primary.

Abstract

A 70-year-old woman with a 6-month history of poor hygiene presented with a right occipital mass, ulceration, and neck swelling. The right occipital region was infested with approximately 100 fly maggots, and the mass contained a foul-smelling abscess. Maggots were removed, and the mass was drained, irrigated, and dressed with padding. Ceftriaxone 1 g/day was administered for 6 days. The patient was transferred on hospital day 32. Blood cultures obtained at admission were positive at 17.3 hours. Gram stain revealed both Gram-positive cocci and Gram-negative rods. However, only Providencia stuartii, Ignatzschineria indica, and Desulfovibrio desulfuricans were subsequently identified. Aerobic reculture of the initial blood culture bottle was performed for 4 days, followed by repeated incubation under 5% CO₂ and anaerobic conditions. A 1 mm colony adjacent to I. indica growth was isolated after CO2 incubation and identified as Fastidiosipila sanguinis by 16S rRNA analysis. Myiasis, a parasitic disease caused by dipteran larvae, can lead to the detection of maggot-associated bacteria in blood cultures. Ignatzschineria species, particularly I. indica, are most commonly isolated in myiasis patients. These organisms are typically associated with blood cultures from unhygienic male patients, although cases in females with adenocarcinoma have been reported. Fastidiosipila sanguinis has only been documented in three cases since its description in 2005, with its origin remaining unknown. In this case, the origin of F. sanguinis was presumed to be the myiasis.