Wound Infections from Taiwan Cobra (Naja atra) Bites: Determining Bacteriology, Antibiotic Susceptibility, and the Use of Antibiotics-A Cobra BITE Study

Abstract

Wound necrosis and secondary infection are common complications after Naja atra bites. Clinical tools to evaluate the infection risk after Taiwan cobra bites are lacking. In this Cobra BITE study, we investigated the prevalence of wound infection, bacteriology, and corresponding antibiotic usage in patients presenting with Taiwan cobra snakebites. Patients with wound infection lacking tissue necrosis were included in developing Cobra BITE score utilizing univariate and multiple logistic regression, as patients with wound necrosis require antibiotics for infection treatment. 8,295,497 emergency department visits occurred in the span of this study, with 195 of those patients being diagnosed as having cobra bites. Of these patients, 23 had wound necrosis, and 30 had wound infection, resulting in a wound infection rate of 27.2% (53/195). Enterococcus faecalis and Morganella morganii were the main bacteria identified in the culture report regardless of whether patients' wounds had necrosis. As per our Cobra BITE score, the three factors predicting secondary wound infection after cobra bites are hospital admission, a white blood cell count (in 103/µL) × by neu-trophil-lymphocyte ratio value of ≥114.23, and the use of antivenin medication. The area under the receiver operating characteristic curve for the Cobra BITE score system was 0.88; ideal sensitivity and specificity were 0.89 and 0.76. This scoring system enables the assessment of wound infections after N. atra bites, and it could be modified and improved in the future for other Naja spp. bites.

Keywords: Naja atra; Taiwan cobra; snakebites; wound infections.

Figure 1

Study flow diagram for Cobra BITE score. The enrolled cobra bites patients were divided into wound tissue necrosis and nonnecrosis group. Patients were defined as having wound necrosis if they met the criteria of positive wound/pus culture or admission diagnoses of cellulitis, abscess, and necrotizing fasciitis. The nonnecrosis wound infection group was compared with the no wound infection group to develop the Cobra BITE score. The bacteriology of necrosis wound and nonnecrosis wound infection groups was employed to provide the clinical application of antibiotic administration for Taiwan cobra bites.

Figure 2

Cobra BITE scores and wound infection rates. Cobra BITE scores and wound infection rates. The higher the score was, the higher the wound infection rate. With an optimal cutoff point of 7, the sensitivity and specificity of Cobra BITE score were 0.89 and 0.76, respectively.

Figure 3

Receiver operator characteristic curve of Cobra BITE score. AUC: area under the curve. The receiver operator characteristic curve of Cobra BITE score was 0.88.