evaluation of 99mtc-ubiquicidin 29-41 scintigraphyin in differentiation of bacterial infection from sterile inflammationin diabetic foot

introduction: ubiquicidin (ubi) 29-41 is a synthetic antimicrobial peptide that binds with the microbial cell membrane at the location of infection. this study was conducted to evaluate its probable efficacy as an infection-imaging agent with potential to differentiate bacterial infection from sterile inflammation in humans. methods: fifteen diabetic foot patients (10 males and 5 females) with suspected bacterial infection, prior to starting antibiotic treatment, were selected for this study. first a routine three phase bone scan and later a 99mtc-ubi scan was performed for all the patients. 555-740 mbq of 99mtc-ubi was injected intravenously. a 10 minute dynamic study was followed by spot views of the suspected region of infection and corresponding normal areas (liver and kidneys) at 60 and 120 min. whole-body anterior and posterior images were also acquired. to interpret the studies as positive or negative, visual score (0 -3) was used, with scores of 0 (minimal or no uptake; equivalent to soft tissue) and 1 (mild; less uptake than in liver) being considered negative and scores of 2 (moderate; uptake equal to or greater than that in liver) and 3 (intense uptake equal to or greater than that in kidneys) being considered positive. results: of 15 studies performed with 99mtc-ubi, all had positive bacterial cultures. the result of bone scan was positive for osteomyelitis in 12 patients (80%). 99mtc-ubi scintigraphy was positive in 6 patients, but negative in nine. the sensitivity of 99mtc-ubi for detection of infection was therefore 40%. from 12 patients who had positive bone scans, only 6 had a positive 99mtc-ubi (50%) indicating the sensitivity of 50% for 99mtc-ubi in osteomyelitis cases. 99mtc-ubi was not positive in any patient who had evidence of soft tissue infection in the bone scan. conclusion: although 99mtc-ubi 29-41 was well tolerated by all the patients without any side effects, considering low sensitivity of this agent, this radiopharmaceutical is not of great value for diabetic foot infection diagnosis.