Ecthyma Gangrenosum Resulting From Microbial Substitution: A Rare Case Report

Ecthyma gangrenosum (EG) is an infectious disease characterized by vesicles or blisters which rapidly evolve into pustules and necrotic ulcers, sometimes accompanied with fulminant bacteremia [1]. Although microbial substitution (MS) to Pseudomonas aeruginosa can occur during long-term antibiotic therapy, EG associated with MS has been rarely reported. We experienced a case of EG resulting from MS associated with prolonged antibiotic administration and continuous duodenal drainage after cholecystectomy. A 53-year-old woman was referred with a 1-day history of ulceration around a percutaneous duodenal cannula placed 1 month earlier (Figure 1a). The next day, purpura and ulceration appeared under the right breast (Figure 1b) as well as on the left thigh (Figure 1c) and the right forearm (Figure 1d). She had myelosuppression (neutrophil count, 200/μL) due to advanced fallopian tube cancer treated with paclitaxel and carboplatin. Cholecystectomy for cholecystitis with gallstones resulted in duodenal injury, requiring cannula placement. Postoperatively, a periduodenal abscess developed, necessitating prolonged drainage. Bacterial examination at the cholecystectomy detected Escherichia coli in dissected biliary system, resulting in the administration of E. coli-sensitive cefmetazole. The examination at 5 days before the skin ulcer formation failed to detect any bacteria in the blood. Blood examinations at the ulcer formation showed white blood cell count, 1100 /μL and C-reactive protein, 32.71 mg/dL. P. aeruginosa was isolated from cultures of peripheral blood, skin ulcer tissue surrounding the cannula, and cannula discharge, as well as from a lesion on the upper arm. The isolates exhibited identical antimicrobial susceptibility profiles, indicating a common source of infection. On the other hand, E. coli was not detected from them. Based on them, the diagnosis of EG associated with P. aeruginosa resulting from MS was made. The patient was treated with sensitive antibiotics of meropenem. The infectious condition was controlled after 2 months under the antibiotics administration. However, the patient died due to the progression of fallopian tube cancer after 3 months. There are a few reports of EG in association with central venous catheter and tracheotomy tube [2]. However, this case was specific in the following two points: (i) EG appeared as MS disease, and (ii) the disease was associated with percutaneous cannula for digestive system. During a 1-month course of cefmetazole targeting E. coli, which was isolated from intraoperative bile cultures, P. aeruginosa, which was not sensitive to cefmetazole, may have proliferated in the condition of myelosuppression [3]. Then, the bacteria may have infected cutaneous tissue around the cannula, resulting in skin ulcer formation. Subsequently, EG may have developed under the immunosuppression, leading to the septic condition [4]. The rare case report provides the evidence that EG can appear as MS disease. EG has been reported to develop in association with the infection of Staphylococcus aureus and Streptococcus pyogenes, and Klebsiella pneunomiae in addition to P. aeruginosa [5]. The facts suggest that long-term administration of antibiotics non-sensitive to these bacteria may potentially lead to MS, resulting in EG. Dermatologists should be aware of the disease resulting from MS. The authors would like to thank Masahiro Kanbe, Master of Arts and Sciences, who was involved in immunohistochemistry. The authors have nothing to report. Ethical approval for this case report was obtained from the Ethics Committee of the Jikei University School of Medicine, and written informed consent was obtained from the patient. The authors declare no conflicts of interest. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.