Bacterial infection secondary to Trimeresurus species bites: A retrospective cohort study in a university hospital in Bangkok.

Abstract

Trimeresurus spp. (green pit viper [GPV]) inhabit several Southeast Asian countries. They account for more than 90% of snake envenomations in Bangkok. GPV venom causes coagulopathy from a thrombin-like effect and thrombocytopaenia. Envenomation can also cause local tissue reactions. The present study primarily aimed to determine the bacterial infection rate from GPV (Trimeresurus spp.) bites. Antibiotic use, microbiology report, and clinical course between those with and without infection were secondary objectives. The present study took place at Vajira Hospital, Navamindradhiraj University. Medical records of patients more than 15 years old, bitten by GPV from our Toxicology Registry between 2015 and 2019, were reviewed by two chart extractors. Vital signs, pain scores, local reactions, time from bite to diagnosis of infection, use of antibiotics, bacterial culture samplings and complications were recorded. The infection rate was reported in percentages. Univariate analysis was utilised to determine risk factors for infection. The study included 123 patients over a 5-year period. The majority were male, 83 cases (67.5%). Overall, bacterial infection occurred in eight cases (6.5%). The median time from bite to infection diagnosis was 41.5h (interquartile range 25.5-68.5). The antibiotic prescription rate was 12.2%. Haemorrhagic bleb was the only risk factor for infection (OR 22.4, 95% confidence interval 3.6-140.2). All bacterial culture samplings were negative. The non-infection group had a decreasing pain score throughout each follow-up visit. We found a low infection rate from GPV bites even without antibiotics suggesting prophylactic antibiotics should not be routinely prescribed in cases of GPV bite.