High Rates of Antibiotic Resistance in Infected Diabetic Foot Ulcers

In patients treated with early ambulatory surgical debridement (EASD) to avoid amputation resulting from infected diabetic foot ulcers, there was a high frequency of positive extended spectrum beta-lactamase (ESBL) Enterobacteriaceae and methicillin-resistant Staphylococcus aureus (MRSA) and high resistance to antibiotics such as ciprofloxacin, ceftriaxone, and clindamycin, according to research presented at ENDO 2017, April 1-4, in Orlando, Florida.

Marlon Yovera-Aldana from the National University of Piura in Peru, and colleagues conducted a cross-sectional study at the Edgardo Rebagliati Martins National Hospital between 2010 and 2014. They evaluated aerobic bacteria cultures from 88 patients who had undergone EASD. Cultures were taken from the base of the ulcer after debridement.

Of the 88 patients, 81.8% were men with an average age of 60.6±12.6. Median time for diabetes was 15 years; hemoglobin A1c was lower than 7% in only 18.7% of patients.

Using the Meggitt-Wagner classification, the severity of the foot ulcers were: 39.8% grade 3; 40.9% grade 4; and 1.1% grade 5. Infection severity, as defined by the Infectious Diseases Society of America, were: mild in 11.4%; moderate in 80.7%; and severe in 7.9% of patients.

The most frequent isolated bacteria were:

• Escherichia coli: 33.7%
• Enterococcus faecalis: 14.1%
• Staphylococcus aureus: 13.3%
• Proteus mirabilis: 10.2%
• Morganella morganii: 7.0%
• Citrobacter freundii: 5.5%
• Pseudomonas aeruginosa: 4.7%

In Gram-negative bacteria, 32% were ESBL-positive Enterobacteriaceae. Enterobacteriaceae showed no resistance to carbapenems, but P aeruginosa showed an 80% to 100% resistance.

In ESBL-negative Enterobacteriaceae, 69% of patients were resistant to ciprofloxacin and 56% were resistant to ceftriaxone. While Acinetobacter baumannii was found in only 2.3% of cases, it showed 100% resistance to all antibiotics.

In Gram-positive bacteria, 70.5% were MRSA. MRSA showed resistance to clindamycin and ciprofloxacin (89% and 100%, respectively). Non-MRSA also showed resistance to clindamycin and ciprofloxacin (50% and 66%, respectively). There was 0% resistance to vancomycin in all Gram-positive bacteria.

Based on these findings, until ulcer culture results have been obtained, the researchers concluded that “a carbapenem with vancomycin is the least resistant initial combination to use” in patients with an infected diabetic foot ulcers.

Reference

Yovera-Aldana M, Rodríguez A, Vargas M, et al. Bacterial resistance in patients with infected diabetic foot without major amputation outcome in a Peruvian national hospital. Presented at: ENDO 2017, April 1-4, 2017, Orlando, Florida. Abstract LB SUN 78.