Effect of delay to surgery and skin preparation upon bacterial growth in patients affected by proximal humeral fracture: a microbiological study.

Introduction. Fractures of the proximal humerus (PHF) are a social problem important either for the high frequency of this disease in the elderly population or the high cost in terms of disability and health care. Although the majority of the fractures can be treated conservatively, for some fractures surgical treatment remains the first choice. A high number of complications have been described regardless of the type of surgical treatment chosen. Infection is one of the complications that potentially has the worst impact on the patient paradoxically less known. To reduce the incidence of postoperative infection in PHF patients is essential to know the risk factors for the occurrence of such complication. Since the delay of surgery and preoperative skin preparation antibiotic are potentially important risk factors in the development of deep microbial infection after PHF, the effect of these variables on skin microbial flora at the level of the surgical site was evaluated. Materials and methods. Consecutive patients recruited at the Mauriziano Umberto I Hospital affected by PHF were subjected to skin swab collection in the area of the deltopectoral approach at the time of the fracture (day 0) and at the time of surgery (days from 0 to >8). At the time of surgery the skin swabs were taken either in an area with single preparation (povidone-iodine) or double skin preparation (chlorhexidine-gluconate solution plus povidone-iodine). The swabs were processed for qualitative and quantitative microbiological analysis by cultural techniques to define bacteria present at surgical site. Results. According to this study we highlighted that the delay of surgery influences the microbial colonization of the skin in the deltopectoral approach: an exponential raise of the bacterial load was observed after 5 days from trauma for all isolates, including potentially pathogen bacteria such as Staphylococcus aureus, Propionibacterium acnes and coagulase-negative staphylococci. The significant increase of the number and the change of the type of local skin bacteria could be due to the immobilization with a bandage, often without the possibility of skin washing, in patients that underwent to surgery after some days from trauma. This might justify the correlation between delay of surgery and risk of infection. Moreover, we proved that either the single or double skin preparation was efficacious in reducing or breaking down the bacterial load. Discussion and conclusions. From these results we obtained a deeper understanding of the role of the delay time to surgery and of the disinfection protocol in the reduction of the infection rates in patients affected by PHF by contributing to a safer patient follow up and to a relevant decrease of costs.