Which test(s) can best identify the causative pathogen(s) and result in tailored use of antibiotics?

Abstract

We read with great interest the paper by Shaoling Yang et al.¹ who in their meta-analysis showed that the prevalence of MDR bacteria in DFUs was 50.86% (95% confidence interval (CI) 41.92%–59.78%), the prevalence of MDR gram-positive bacteria (GPB) in DFUs was 19.81% (95% CI:14.35%–25.91%) and the prevalence of MDR gram-negative bacteria (GNB) in DFUs was 32.84% (95% CI: 26.40%–39.62%). These results have significant implications for the correct diagnosis and appropriate use of antibiotics in antimicrobial stewardship to avoid treating patients with only colonization. We would like to further discuss these implications.

The recent IDSA guidelines² ask an important question: “In a person with diabetes and infection of the foot, which test(s) can best identify the causative pathogen(s), and result in tailored use of antibiotics?

ISDA guidelines answer this question with the following recommendation: “In a person with suspected soft tissue DFI, consider a sample for culture to determine the causative microorganisms, preferably by aseptically collecting a tissue specimen (by curettage or biopsy) from the wound.”

The scientific basis for this claim is given by two systematic reviews^{3, 4}: two prospective studies reported higher sensitivity and specificity of tissue samples for culture results compared to surface swabs.^{5, 6} However, we realize that collecting a tissue sample may require slightly more training and carry a slight risk of discomfort or bleeding. Still, we believe that the benefits outweigh the minimal risk of harm of carrying out targeted therapy in a proper view of antimicrobial stewardship. Considering the above, we think that Shaoling Yang et al. have a more accurate result, it would have been better to divide the studies between those who were diagnosed with swabs and those who were diagnosed with a biopsy.

Elisabetta Pagani: Conceptualization. Raffaele Bruno: Conceptualization; writing – review and editing.

The authors declare no conflicts of interest.