Inter-rater and intra-rater reliability outcomes of a rapid bacteria counting system with pressure ulcer samples

Objective: Evaluating bacterial load in pressure ulcers (PUs) is key to combat infection; therefore, using technologies to measure bacterial count can be particularly useful. A rapid bacteria counting system was recently developed and introduced to the wound care field. However, its reliability was not established. This cross-sectional study aimed to evaluate the inter-rater and intra-rater reliability of bacterial count using this rapid counting system. Method: We took bacterial swabs from patients with category I or greater PUs to assess inter- and intra-rater reliability. An assessor swabbed the longest axis of the PU once and bacterial counts were measured using a rapid bacteria counting system. To confirm the inter-rater and intra-rater reliability, intraclass correlation coefficients (ICCs) were calculated. Results: We took 63 and 57 pairs of bacterial counts from 13 patients with 16 category I or greater PUs to assess inter- and intra-rater reliability, respectively. Overall ICCs [95% confidence intervals (CI)] for the bacterial counts were 0.83 [0.73-0.90, p<0.001, inter-rater reliability, n=63], and 0.89 [0.82-0.94, p< 0.001, intra-rater reliability, n=57]. Conclusion: A high level of reliability for counting bacterial numbers in PU sites was confirmed. The results should encourage clinicians and researchers to use this type of device for the real-time assessment of wound bacterial bioburden at the patient's bedside. Declaration of interest: This study was partly supported by a grant-inaid for Scientific Research A from the Japan Society for the Promotion of Science. The authors have no conflict of interest to declare.