Case Presentation: A 49-year-old man with uncontrolled diabetes type 2 presented to the hospital for right foot pain of three-weeks duration. He had tachycardia to 102/min, a temperature of 101.3 F, and white blood cell (WBC) count of 26.8 x109 cells/L. An X-Ray of his right foot was consistent with osteomyelitis and necrotizing fasciitis. Two sets of admission blood cultures were negative. He underwent right foot transmetatarsal amputation with two subsequent revisions. The cultures had growth of Streptococcus agalactiae, Prevotella denticola, Actinomyces turicensis, and Solobacterium moorei. Bone margins were negative for osteomyelitis; patient received ampicillin-sulbactam then a five-day course of amoxicillin-clavulanate. He failed to change his wound dressing after two weeks as he run out of supplies. Three weeks later, patient presented with a two-day history of right foot foul-smelling discharge. Exam revealed a poorly healing right foot wound manifesting as surgical site dehiscence, with maggots embedded within and along the surgical site. He had elevated WBC count of 11.4×109/L. CT scan could not rule out infection and the ankle brachial index showed normal perfusion. Blood cultures this admission grew Wohlfahrtiimonas chitiniclastica, Ignatzschineria spp., and Citrobacter koseri. He was started on vancomycin, cefepime, and metronidazole. He underwent a right transmetatarsal revision. Tissue cultures showed growth of W. chitiniclastica, C. koseri, Proteus vulgaris, Morganella morganii, Klebsiella pneumoniae, Vagococcus fluvalis, and Enterococcus faecalis. Then, a Lisfranc amputation was performed with clear, viable margins. He was sent to a long-term care facility for antibiotics and wound management, during which time he developed worsening wound drainage. Therefore, he was continued on six weeks of piperacillin-tazobactam.
Discussion: W. chitiniclastica and Ignatzschineria spp, are gram-negative bacillus implicated in the pathogenesis of maggot-infested foot wounds, or myiasis [1]. Risk factors for W. chitiniclastica infections are homelessness, poor hygiene, chronic vascular diseases, and low socioeconomic status [1]. Lucilia sericata is possibly the vector for transmission of W. chitiniclastica in the Americas [1], and Ignatzschineria spp worldwide [2]. The spectrum of illness ranges from local wound infection to bacteremia [1]. While infections, as seen in our case, are likely to result from maggot infestations, maggot excreta have been known to possess potent antibacterial activity [3]. We hypothesize that this microbicidal activity inhibited the growth of Staphylococcus aureus, and Staphylococcus epidermidis, the usual bone cultured pathogens in diabetic foot infections. In terms of therapy, W. chitiniclastica infection was mostly treated with B-lactams with overall favorable outcomes [4]. For Ignatzschineria spp, aminoglycosides and fluoroquinolones are options for treatment. We had successful eradication of both pathogen with piperacillin-tazobactam treatment.
Conclusions: Maggot infestation results in the growth of rare pathogens like W. chitiniclastica and Ignatzschineria spp. in wounds. We urge careful consideration of atypical pathogens in case of failure of improvement on existing antimicrobial regimen and to include empiric coverage in maggot-infested wounds.