Abstract: Objective · To examine the seasonality of post-traumatic wound infection (PWI) and surgery site infection (SSI) from the perspectives of
occurrence and microbiological distribution. Methods · The cumulative incidences of PWI and SSI in different seasons were respectively calculated
and compared in a cohort of 2 177 patients who sustained open-wounded injuries in the upper or lower extremity and a cohort of 11 809 patients
receiving selective orthopedic operation from 2013 to 2015 in Shanghai Sixth People’s Hospital. Multifactorial linear regression was used to measure the
influence of meteorological parameters on PWI incidence. Moreover, the microbiological distribution of PWI and SSI was analyzed on a seasonal basis.
Results · The incidence of PWI in the patients was 2.20% from 2013 to 2015, and there were significant seasonal patterns (1.04% in spring, 3.52% in
summer, 3.10% in autumn, 0.71% in winter, P=0.004). The incidence of SSI was 0.21%, and there was no seasonal difference (P=0.809). Only average
temperature (P=0.002, β=0.016) was correlated with the occurrence of PWI in multifactorial linear regression analysis. Microbiological analysis revealed
the dominance of Gram-negative bacteria in SSI cases during the summer and autumn (P=0.021). However, this trend was not observed in PWI cases
(P=0.694). Conclusion · There is a seasonal pattern in PWI occurrence with peaks in summer and autumn, which is correlated with temperature. There is
no seasonal difference in SSI incidence, but SSI cases were dominantly infected by Gram-negative bacteria in summer and autumn.

Key words: post-traumatic wound infection, surgery site infection, season, temperature, gram-negative bacteria