Background/Objectives: Current international guidelines recommend choosing an empirical antibiotic regimen for treating diabetic foot infections (DFI) based largely on clinical severity of the infection and local microbiological epidemiology. This may lead to selecting unnecessarily broad-spectrum initial empiric antibiotic therapy. Methods: Using data from our hospital in a large Swiss city, we retrospectively analyzed the performance of the Gram-stained smears of predominantly deep surgical DFI specimens processed by our microbiology laboratory in predicting the microorganism grown on standard cultures. We excluded episodes with paucibacillary stain results, which we interpret as contamination. Results: Among 1235 operated moderates or severe DFIs, Gram-stained smear was reported in 321 (26%) of cases, and showed bacteria in 172 episodes (54%) of these. Overall, among Gram stain results with organism seen, the sensitivity, specificity, accuracy, positive and negative predictive values of the Gram stain smear when compared with the cultures was 56%, 93%, 97%, and 38%, respectively. The accuracy was 73%. The corresponding statistical values specifically for Gram-negative bacteria were 61%, 97%, 50%, and 82%. Conclusions: The results of routine Gram stain smears of deep intraoperative DFI specimens generally lack sufficient sensitivity, and was only useful to reasonably exclude a DFI caused predominantly by Gram-negative bacteria. For Gram-stained smears results to be useful for guiding antibiotic stewardship, we need prospective trials to assess their value in different types of DFIs.

Purpose: Methods: Results: Conclusion:

Background/Objectives: In orthopedic (diabetic) foot surgery, the serum C-reactive protein (CRP) is frequently measured not only as a diagnostic tool, but also as a control inflammatory marker in the follow-up of operated surgical site infections (SSI) Methods: We investigate the predictive value of the post-debridement routine (control) serum CRP level in adult (diabetic) patients with SSI in the foot. We exclude community-acquired (diabetic foot) infections and focus on the predictive accuracy of routine (control) CRP measurements in terms of ultimate therapeutics failures. Results: The median pre- and postoperative CRP were 25 mg/L and 8.8 mg/L, respectively. In group comparisons and multivariate assessment, neither the immediate (relative and absolute) drop of the serum CRP level, nor its values between 5 and 8 weeks and between 11 and 14 weeks predicted the failure risk of 19%. In contrast, in cases of a surprisingly elevated CRP levels, this finding leads to unnecessary radiological, clinical and laboratory exams during clinical treatment of infections. Conclusions: Routine, postoperative CRP monitoring during the treatment of established (diabetic) foot SSIs is futile, unnecessarily costly, and should be avoided in favor of a clinical surveillance of the postoperative evolution.

Current international guidelines recommend choosing an empirical antibiotic regimen for treating diabetic foot infections (DFI) based largely on the clinical severity of infection and the local microbiological epidemiology. This may lead to selecting unnecessarily broad spectrum initial empiric antibiotic therapy. Using data from our hospital in a large Swiss city, we retrospectively analyzed the performance of the Gram-stained smears of predominantly deep surgical DFI specimens processed by our microbiology laboratory in predicting the microorganism grown on standard cultures. We excluded episodes with paucibacillary stain results, which we interpret as contamination. Among 1,235 operated moderates or severe DFIs, Gram-stained smear was reported in 321 (26%) of cases, and showed bacteria in 172 episodes (54%) of these. Overall, among Gram-stain results with organism seen, the sensitivity, specificity, positive and negative predictive values of the Gram-stain smear when compared with the cultures was 56%, 93%, 97%, and 38%, respectively. The corresponding statistical values specifically for Gram-negative bacteria were 61%, 97%, 50%, and 82%. We conclude that the results of routine Gram-stain smears of deep intraoperative DFI specimens generally lack sufficient sensitivity, and was only useful to reasonably exclude a DFI caused predominantly by gram-negative bacteria. For Gram-stained smears results to be useful for guiding antibiotic stewardship, we need prospective trials to assess its value in different types of DFIs.

Background/Objectives: In orthopedic (diabetic) foot surgery, the serum C-reactive protein (CRP) level is frequently measured not only as a diagnostic tool, but also as a control inflammatory marker in the follow-up of postoperative surgical-site infections (SSIs) Methods: We investigated the predictive value of the post-debridement routine (control) serum CRP level in adult (diabetic) patients with an SSI in the foot. We excluded community-acquired (diabetic foot) infections and focused on the predictive accuracy of routine (control) CRP measurements in terms of ultimate therapeutic failures. Results: The median pre- and postoperative CRP levels were 25 mg/L and 8.8 mg/L, respectively. In group comparisons and multivariate assessment, neither the immediate (relative and absolute) drop in the serum CRP level, nor its values between 5 and 8 weeks and between 11 and 14 weeks predicted the failure risk of 19%. In contrast, in cases of surprisingly elevated CRP levels, this finding leads to unnecessary radiological (median costs approximatively USD 200), clinical, microbiological urinary sample (median costs USD 50), and laboratory (one CRP sample USD 10) exams. These additional exams also likely prolong the duration of hospitalization by one to two days (e.g., whilst awaiting the microbiological results) and often generate unnecessary consultations among internist and/or infectious diseases experts (USD 50). Conclusions: Routine, postoperative CRP monitoring during the treatment of established orthopedic (diabetic) foot SSIs is unnecessarily costly, and should be avoided in favor of clinical surveillance of the postoperative evolution.