Contamination of wounds with fecal bacteria in immuno-suppressed mice

Abstract

immunocompromised patients are predisposed to chronically infected wounds. especially ulcers in the dorsal region often experience secondary polymicrobial infections. However, current wound infection models mostly use single-strain bacteria. to mimic clinically occurring infections caused by fecal contamination in immunocompromised/immobile patients, which differ significantly from single-strain infections, the present study aimed at the establishment of a new mouse model using infection by fecal bacteria. Dorsal circular excision wounds in immunosuppressed mice were infected with fecal slurry solution in several dilutions up to 1:8,000. Impact of immunosuppressor, bacterial load and timing on development of wound infections was investigated. Wounds were analyzed by scoring, 3D imaging and swab analyses. Autofluorescence imaging was not successful. Dose-finding of cyclophosphamide-induced immunosuppression was necessary for establishment of bacterial wound infections. Infection with fecal slurry diluted 1:166 to 1:400 induced significantly delayed wound healing (p < 0.05) without systemic reactions. Swab analyses post-infection matched the initial polymicrobial suspension. The customized wound score confirmed significant differences between the groups (p < 0.05). Here we report the establishment of a simple, new mouse model for clinically occurring wound infections by fecal bacteria and the evaluation of appropriate wound analysis methods. in the future, this model will provide a suitable tool for the investigation of complex microbiological interactions and evaluation of new therapeutic approaches. Each year, 305 million people suffer from acute, traumatic or burn wounds, globally 1. The European community spends 2-4% of the total health expenditure on wound treatment 2. Wounds can arise from injuries, surgeries and as a consequence of extrinsic factors and underlying comorbidities (e.g. vascular diseases or diabetes). Hence, the general classifications differentiate between acute (e.g. burns or surgical wounds) and chronic wounds, (e.g. vascular, diabetic or pressure ulcers). In healthy individuals, the acute wounds generally heal without complications with basic supportive care and minimal infection risk. However, comorbidities and/or risk factors such as vascular diseases, diabetes, a weak immune system, bacterial colonization (especially with pathogens of high intrinsic virulence/resistance) may frequently lead to the development of a chronically infected wounds. Skin and soft tissue infections (SSTIs) represent the most common infections in humans 3. The associated impairment of wound healing incurs financial and logistic burden to the health care system and lowers the quality of life in affected patients 4. In the clinical setting, secondary infections of chronically non-healing wounds further aggravate their complex pathology and delay the healing processes. Immunocompromised patients are prone to develop chronically infected wounds 5 , and especially patients with pressure ulcers often experience seconda...

Recent Advancements on Photothermal Conversion and Antibacterial Applications over MXenes-Based Materials

“…As a global problem, uncontrollable harmful bacterial proliferation has posed great threat to public health, which eventually caused economic burdens to the infected patients and the whole society [ 1 , 2 ]. The infectious bacteria always brought in wound infections [ 3 , 4 ], disease transmission [ 5 , 6 ], water contamination [ 7 ], soil contamination [ 8 ], and widespread corrosions [ 9 ]. From a traditional viewpoint, antibiotics have held the top priority in the eradication of bacterial growth.…”