gms | German Medical Science

Objectives: In vivo biofilm models play major role to study biofilm development, morphology, and regulatory molecules involve in biofilm. Thus, in vivo models helps to reveal therapeutic targets to treat biofilms as well as to screen the antimicrobial compounds to eradicate the biofilms. Due to ethical restrictions, the use mammalian models are replaced with other alternative models in basic research. Recently, we have developed insect infection model G. mellonella larvae to study implant associated biofilm infections. This model organism is easy to handle, cheap and ethical restriction free and could be used for the high through put screening of antimicrobial compounds to treat biofilm. To promote the use of this model in basic research we aimed to validate this based on the typical biofilm features such as less susceptible to the antibiotics, complexity of the biofilm structure and gene expression profile of biofilms.

Methods: G. mellonella larvae are maintained at 30^oC on artificial diet in an incubator. Titanium and Stainless steel K-wires were cut into small pieces with size of 4mm.For the infection process, implants were pre-incubated in specified bacterial growth culture S. aureus EDCC 5055 at 1x106 CFU/ml for 30 min at 150 rpm shaking conditions. Later, these implants were washed with 10ml PBS and implanted in the larvae as mentioned. To analyze the susceptibility of the biofilms towardsantibiotics, the larvae were treated with gentamicin and compared survival with with planktonic infection in G. mellonella. To reveal the complex structure of biofilm, the implants were removed and processed for the MALDI analysis. Whole genome-based transcriptome of biofilm was performed to explore the changes in transcriptional landscapes.

Results and Conclusion: The results are very promising to validate the use of G. mellonella as in vivo model to study the biofilm formation on implanted materials. The gentamicin treatment could rescue the larvae from the planktonic infection, but not from the biofilm infection on the implants. Further, the MALDI analysis could reveal the complex structure and components ofS. aureus biofilm formed on the implant inside the larvae. Finally, the transcriptomic analysis reveal the gene expression changes and regulatory networks that could be compared to normal biofilm gene expression profile.