Bacterial reservoir in deeper skin is a potential source for surgical site and biomaterial-associated infections.

BACKGROUND: The origin of surgical site and biomaterial-associated infection is still elusive. Micro-organisms contaminating the wound may come from the air in the operating theatre, the surgical team or the skin of the patient. The skin of patients is disinfected prior to surgery, but bacteria deeper in the skin (e.g. in sweat glands or sebaceous glands) may not be reached. METHODS: A preliminary cohort study was performed to study the origin of surgical site and biomaterial-associated infection between May 2020 and February 2021. In order to investigate whether cutaneous microbiota colonize the wound when released from the skin upon cutting, aerobic and anaerobic bacteria were isolated, quantified and identified from the skin of 99 patients undergoing trauma surgery, before and after skin disinfection, from knife blades and from the wound directly after the first cut. RESULTS: Ninety-nine percent of the patients were culture-positive before disinfection with chlorhexidine. Of these, 40% were still culture-positive after disinfection. Of these, 54% had a positive culture of the wound after cutting the skin. Twenty percent of the patients with a negative culture after disinfection had a positive wound culture after cutting the skin. Staphylococcus epidermidis and Cutibacterium acnes were the most commonly cultured bacterial species. In 9% of cases, more than 100 bacterial colonies were cultured from the wound; this may cause biomaterial-associated infection. CONCLUSION: Bacteria residing in the skin and not eradicated by disinfection may enter the surgical wound upon cutting, resulting in contamination which may cause biomaterial-associated infection.

Current osteomyelitis mouse models, a systematic review.

Osteomyelitis is an inflammatory bone disease caused by an infecting microorganism leading to a gradual bone loss. Due to the difficulty in studying osteomyelitis directly in patients, animal models allow researchers to investigate the pathogenesis of the infection and the development of novel prophylactic, anti-inflammatory and antimicrobial treatment strategies. This review is specifically focused on the in vivo mouse osteomyelitis studies available in literature. Thus, a systematic search on Web of Science and PubMed was conducted using the query "(infection) AND (mice OR mouse OR murine) AND (model OR models) AND (arthroplasty OR fracture OR (internal fixator) OR (internal fixation OR prosthesis OR implant OR osteomyelitis)". After critical assessment of the studies according to the inclusion and exclusion criteria, 135 studies were included in the detailed analysis. Based on the model characteristics, the studies were classified into five subject groups: haematogenous osteomyelitis, post-traumatic osteomyelitis, bone-implant-related infection, peri-prosthetic joint infection, fracture-related infection. In addition, the characteristics of the mice used, such as inbred strain, age or gender, the characteristics of the pathogens used, the inoculation methods, the type of anaesthesia and analgesia used during surgery and the procedures for evaluating the pathogenicity of the infecting micro-organism were described. Overall, the mouse is an excellent first step in vivo model to study the pathogenesis, inflammation and healing process of osteomyelitis and to evaluate novel prophylaxis and treatment strategies.