The most common complication in open fractures is infection, which often escalates to sepsis, osteomyelitis, and amputations. The use of prophylactic antibiotics is one of the most effective strategies to prevent infection. The prevailing bacterial isolate patterns must guide the choice of antibiotics for both prophylactic and empiric therapy. This study aims to describe the bacterial isolate profiles in infected open fractures. A prospective cross-sectional study was carried out at Kenyatta National Hospital, Kenya, between October 2019 and January 2020. 66 infected open fractures were identified and pus swabs/infected tissue specimens taken for bacterial cultures. Other data were collected from patient interviews and their hospital records. Results revealed that the culture growth rate was 79%. Gram-negative isolates accounted for 73% while Gram-positive isolates were 27%. The most pre-dominant bacterial isolate was Pseudomonas aeruginosa (34%), followed by Staphylococcus aureus (27%), Escherichia coli (20%), Proteus mirabilis (16%) and Klebsiella pneumoniae (3%). There were more gram-negative than gram-positive bacterial isolates. The pre-dominant bacterial isolate was P. aeruginosa followed by S. aureus. The higher proportion of gram negative isolates is in variance with what is widely documented in the literature. The selection of antibiotics for both prophylaxis and empiric therapy should be tailored to the local patterns of bacterial isolates.