Saline-soaked swabs help find more bacteria in dog skin infections

Abstract

BACKGROUND: Canine superficial bacterial folliculitis (SBF) is a common recurrent condition with a growing requirement for culture and susceptibility as a consequence of increased antimicrobial resistance and antimicrobial stewardship. Different opinions persist about the ideal technique for culture sample acquisition, which varies with lesion characteristics. OBJECTIVE: To determine if a difference exists in the recovered quantity of bacteria acquired when sampling nonexudative clinical lesions of SBF (crusts and epidermal collarettes) between a dry culture swab and a saline-moistened culture swab. ANIMALS: Nine dogs with crusts or epidermal collarettes and cytological findings consistent with SBF were recruited. MATERIALS AND METHODS: Each clinical lesion was divided into two halves. One half of the lesion was sampled with a dry cotton sterile swab, while the other half was sampled with a sterile swab saturated with sterile saline. Each lesion was sampled with the culture swab by rolling it over the corresponding half four times. Aerobic quantitative cultures were then performed to determine the number of Staphylococcus-type colonies present. RESULTS: A total of 19 lesions (13 crusts and six epidermal collarettes) were evaluated. Dry culture swab identified a mean staphylococcal bacterial count of 3.83 Logcolony-forming units (cfu)/mL (standard deviation [SD] = 0.70). The saline-soaked culture swab revealed a median bacterial count of 4.41 Logcfu/mL (SD = 0.77). There was a statistically significant difference between the sample collection methods (p = 0.002). CONCLUSIONS AND CLINICAL RELEVANCE: Sterile saline-soaked swabs are more likely than dry swabs to result in increased recovery of bacteria from nonexudative lesions.