Abstract
Aim
To conduct a systematic review of non-rodent animal models (rabbit, pig, dog, goat and sheep) of bone infection. In the future, anti-infective technologies aiming to fight bone infections are depending on evaluation in reliable animal models. Therefore, it is highly relevant to evaluate the scientific quality of existing bone infection models.
Method
PubMed and Web of Science were searched systematically. To be included in the systematic review, publications had to deal with bacterial inoculation of non-rodent animals in order to model bone infections in humans. Data was extracted on study design e.g. bacterial inoculation dose and infection time, methodological quality and post-mortem evaluation with respect to registration and quantification of pathology and microbiology.
Results
In total, 316 publications were included in the systematic review. A substantial lack of study design information (e.g. bacterial identity and infection time) was demonstrated in many of the papers, which hampers reproducibility and continuation of the established work. Furthermore, the methodological study quality was found to be low as definition of infection, randomization, power analysis and blinding were only seldom reported. The use of histology has increased in recent years, but a semi-quantitative scoring of the lesions was often missing, i.e. no objective quantification of outcome. Most of the studies focused on whether the inoculated bacteria were present within the bone tissue post mortem or not. However, very often the bacterial burden was not quantified. In many of the models, different antimicrobial interventions were examined, and the lack of quantitative microbiology makes it difficult to estimate and reproduce the effects objectively. Although, antimicrobial effects were described for most interventions, a lack of sterile outcome was observed in many models. Failure to report a sterile outcome reduces the possibility for obtaining valuable knowledge regarding effective antibiotic doses in-vivo. Based on the present review a standard study template guideline for animal models of bone infections was established. The guideline describes details related to the animal, pathogen, animal + pathogen (infected animal) and post mortem analysis that are of crucial importance for validation of results and reproducibility.
Conclusions
Due to a substantial lack of uniformity we miss the opportunity to get maximal knowledge from the preclinical literature. The new guideline will improve reproducibility of future models and translation of findings to the clinical setting. Bone infection organisations/societies and journal editors should encourage compliance with the new guideline.
Reference: JBJS, 2019, In press
