Reliance on Clinical Signs and Symptoms Assessment Leads to Misuse of Antimicrobials: Post hoc Analysis of 350 Chronic Wounds

Abstract

Objectives: Bacteria frequently impede wound healing and cause infection. Clinicians rely on clinical signs and symptoms (CSS) to assess for bacteria at the point of care, and inform prescription of antibiotics and other antimicrobials. Yet, robust evidence suggests that CSS has poor sensitivity for detection of problematic bacterial burden and infection, hindering antimicrobial stewardship efforts. This study evaluated CSS-based antimicrobial prescribing practices across 14 wound care centers. Approach: Data were analyzed from the fluorescence assessment and guidance (FLAAG) trial, a study of 350 chronic wounds across 20 clinicians. Clinicians reviewed patient history and assessed for CSS using the International Wound Infection Institute infection checklist. Wounds with >3 criteria or any overwhelming symptom were considered CSS+. Bacterial levels were confirmed with quantitative tissue culture of wound biopsies. Results: Antimicrobials (including dressings, topicals, and systemic antibiotics) were prescribed at a similar rate for wounds identified as CSS+ (75.0%) and CSS- (72.8%, p = 0.76). Antimicrobial dressings, the most frequently prescribed antimicrobial, were prescribed at a similar rate for CSS+ (83.3%) and CSS- (89.5%, p = 0.27) wounds. In 33.3% of patients prescribed systemic antibiotics, no CSS were present. Prescribing patterns did not correlate with bacterial load. Innovation: This study is the first to evaluate antimicrobial prescribing trends in a large, multisite cohort of chronic wound patients. Conclusions: Reliance on CSS to diagnose clinically significant bacterial burden in chronic wounds leads to the haphazard use of antimicrobials. Improved methods of identifying bacterial burden and infection are needed to enhance antimicrobial stewardship efforts in wound care. Clinicaltrials.gov ID. NCT03540004.

Keywords: antibiotic prescribing; antimicrobial stewardship; bacterial burden; chronic wounds; clinical decision support; diagnostic pathway; wound clinic.

Conflict of interest statement

The authors declare no financial interests or conflicts of interest to disclose.

Figures

Thomas E. Serena, MD

Figure 1.

Total bacterial load of study wounds identified as negative (CSS−) or positive (CSS+) for CSS based on International Wound Infection Institute (IWII) wound infection criteria. Box and whisker plot of total bacterial load for wounds deemed CSS− (n = 302) and CSS+ (n = 48). Open circles represent individual study wounds; middle lines indicate median bacterial load; error bars indicate range. Of the CSS− wounds, 36 had total bacterial load of 0. Dashed lines at 104 CFU/g represent minimum bacterial threshold at which delayed healing is observed; dashed lines at 105 CFU/g and 106 CFU/g represent minimum bacterial thresholds at which wounds are considered infected and treatment is warranted. ***p < 0.001 by the Mann–Whitney test of log-transformed data. CSS, clinical signs and symptoms; CFU, colony forming units.

Figure 2.

Antimicrobial (a) and antibiotic (b) prescription based on assessment of CSS, patient history, and clinical judgment. Antimicrobials included topicals, dressings and antibiotics (topical or systemic), antibiotics included topicals, oral or intravenous. Percentages reflect proportion of CSS+ and CSS− wounds among all participants (n = 350), participants with bacterial loads of <104 CFU/g (n = 63), and participants with >108 CFU/g (n = 44). p values derived from chi-square tests after correcting for multiple comparisons. Any comparisons for which p-values are not shown were not significant.

Figure 3.

(a) Types of antimicrobials prescribed based on patient history and visual assessment of CSS of infection. Wounds with three or more CSS based on IWII criteria were considered positive for CSS (CSS+). Frequency represents the proportion out of the total number of antimicrobials prescribed for either CSS+ or CSS− wounds. (b) Frequency of specific CSS detected in patients prescribed systemic (oral or intravenous) antibiotics. Values represent % of all patients prescribed systemic antibiotics. Covert, overt, and spreading represent the designated categories of CSS in the IWII guidelines. p values derived from chi-square tests after correcting for multiple comparisons.