Diabetic foot infections in Zagazig University Hospital: bacterial etiology, antimicrobial resistance and biofilm formation
*Corresponding Author E-mail: firstname.lastname@example.org
This study aimed to investigate the etiologic agents of diabetic foot infections, their antimicrobial resistance and biofilm formation ability. 50 non-repetitive samples were taken during a six-month period. Isolation and identification of pathogens were done according to standard procedures. The sensitivity to antimicrobial agents was determined by the disc diffusion method and the assessment of biofilm production was performed by the tube method.
Negative cultures were found in 4 (8%) samples. Polymicrobial infections were found in 22 (44%) samples. A total of 75 bacteria were isolated with an isolation ratio of 1.63 bacteria per patient. Gram-positive cocci were observed in 14.67% of isolates and Gram-negative bacilli in 85.33% of isolates. The most frequent organisms isolated were Proteus mirabilis (20%), E. coli (18.67%), Pseudomonas aeruginosa (16%), Klebsiella pneumoniae and Staphylococcus aureus (10.67% each). Fifty one strains were isolated in polymicrobial cultures. Proteus mirabilis (21.57%), Pseudomonas aeruginosa (19.61%), E. coli (15.69%), Klebsiella pneumoniae (11.76%), and Staphylococcus aureus (7.84%) were the most common organisms recovered in polymicrobial infections.
Imipenem was the most effective antibiotic against both Gram-negative and Gram-positive isolates. High resistance was shown by Acinetobacter baumanii (90.91%) followed by Klebsiella spp. (81.12%), Staphylococcus epidermidis (80%), E. coli (75.97%), Pseudomonas spp. (65.73%), Enterococcus faecalis (60%), Citrobacter freundii (54.55%), Proteus spp. (46.97%), while the least resistance was observed with Staphylococcus aureus (23.75%).
Biofilm production was positive in 70 isolates (93.33%). Among these isolates 44.29% were assessed as strong biofilm forming. Six gram-positive isolates (54.55%) and 31 isolates (48.44%) of gram-negative bacilli were strong biofilm forming. Among the common isolated pathogens, Proteus mirabilis was the predominant strong biofilm producer (80%), followed by Pseudomonas aeruginosa and staphylococcus aureus (50% each) and E.coli (28.57%). Resistance to antibiotics was higher among biofilm forming isolates than non-biofilm forming ones.
Multidrug resistance was found in 81.33% of isolates. Gram-negative bacilli showed higher multidrug resistance (89.06%) than gram-positive cocci (36.36%). The most frequent multidrug resistance pathogens were E. coli (21.31%), Pseudomonas aeruginosa and Proteus mirabilis (19.67% each) and Klebsiella pneumoniae (13.11%). Biofilm production was correlated with multidrug resistance. In 90.16% of MDR pathogens, biofilm formation was positive. The most common MDR biofilm producer pathogens were Pseudomonas aeruginosa and Proteus mirabilis (21.82% each), E. coli (18.18%) and Klebsiella pneumoniae (12.73%).
Due to the great involvement of diabetic foot ulcer in non-traumatic foot amputations, it is of significance to identify the causative pathogens of these ulcers, their antibiogram and biofilm formation in order to select the proper therapy.
Diabetes mellitus, diabetic foot ulcers, aerobic bacteria, resistance profile, biofilm.