- If either beta hemolytic streptococci (in any amount) or total bacterial load of >1e6 CFU/gram of tissue is present in the screening biopsy sample at the ulcer site, the patient should be given a single 7-day course of topical antibiotics and then redebrided and biopsied for quantitative culture. A second biopsy exceeding the limits above will result in exclusion from the study due to the high risk of local infection than may adversely affect ulcer closure.