Determinants of Microbial Load in Infected Diabetic Foot Ulcers: A Pilot Study

We examined the determinants of microbial load in infected diabetic foot ulcers in 62 patients (38 men and 24 women, mean age: 65.63 +/- 12.71 years) with clinically infected diabetic foot ulcers. Tissue cultures were taken from ulcers by 4 mm punches. Ulcer grade (University of Texas classification), neuropathy disability score (NDS), neuropathy symptom score (NSS), ankle-brachial index (ABI), perfusion, extent, depth, infection, and sensation (PEDIS) grade of diabetic foot infection, and laboratory parameters were evaluated in all patients. Total microbial load was positively correlated with the number of isolates on tissue cultures (r(s) = 0.544, P < 0.001), white blood cell count (WBC) (r(s) = 0.273, P = 0.032), and platelet count (PLT) (r(s) = 0.306, P = 0.015). It also exhibited a borderline insignificant positive correlation with PEDIS infection grade (r(s) = 0.246, P = 0.053). In stepwise linear regression analysis, the number of isolates on tissue cultures and WBC were identified as the only two significant parameters accounting for 38% of the variation in the log of total microbial load (adjusted R-2 = 0.380, P < 0.001). In conclusion, patients with infected diabetic foot ulcer exhibit a positive correlation of total microbial load with the number of isolates on tissue cultures, WBC and PLT.