The distribution of causative pathogens and their drug susceptibilities in diabetic foot infections

Objective To investigate the main causative pathogens and their drug susceptibility patterns in diabetic foot infections with different Wagner grades. Methods The bacterial culture results and drug susceptibilities of 705 patients with diabetic foot infections at the Air Force General Hospital from January 2012 to December 2014 were retrospectively analyzed. Enumeration data were compared with Chi-square test. Results Of 1 343 samples collected from 705 patients with diabetic foot, 991 samples revealed pathogen growth. The positive rate was 73.8%. In culture-positive samples, 358 strains were gram-positive, 586 stains were gram-negative, whereas 47 strains were fungi. Pseudomonas aeruginosa, Baumanii and Staphylococcus aureus were dominant. The proportions of gram-positive and gram-negative bacteria in patients with Wagner 1-2 were 48.33%(29/60) and 46.67%(28/60), respectively, and 35.34%(329/931) and 59.94%(558/931), respectively in those with Wagner 3-5 (χ2 =4.324, P=0.038). The composite infection in patients with mild, moderate and sever diabetic foot were 3.41%, 7.84%, and 13.84%, respectively (χ2=11.353, P=0.003). Among gram-negative bacteria, Pseudomonas aeruginosa and Baumanii were dominating floras. Susceptibilities of Pseudomonas aeruginosa to imipenem, piperacillin/tazobactam and ceftazidime were 25.8%, 24.76% and 23.92%, respectively, while susceptibilities of Baumanii to trimethoprim/sulphamethoxazole, imipenem and cefoperazone/sulbactam were 41.71%, 25.13% and 24.29%, respectively. Staphylococcus aureus and Enterococcus faecalis were found to be prevalent among gram-positive bacteria. Staphylococcus aureus was most susceptible to tigecycline and vancomycin (both 100.00%), and Enterococcus faecalis was most susceptible to tigecycline and linezolid (both 100.00%). Conclusions The distribution of pathogenic bacteria in diabetic foot infections patients different Wagner grades varies significantly, and causative pathogens are resistant to multiple antimicrobial drugs. Key words: Diabetic foot; Infection; Pathogen profile; Anti-bacterial agents; Drug susceptibility