Investigation of virulence factors in clinical isolates of stenotrophomonas maltophilia using galleria mellonella model

Aim: In this study, it was aimed to investigate the virulence characteristics of Stenotrophomonas maltophilia isolates, to grow and produce Galleria mellonella larvae as experimental animal model and to show the usefulness of this model in pathogenesis and treatment studies. Materials and Methods: Antibiotic susceptibility status of Stenotrophomonas maltophilia isolates included in the study were determined using MicroScan Neg MIC Panel Type 44 kit according to the manufacturer's instructions. Biofilm formation was evaluated by spectrophotometric microplate method on twitching Müller Hinton medium and spreading on Luria Bertani medium. Galleria mellonella larvae were grown and produced in Zonguldak Bülent Ecevit Üniversitesi Medical Microbiology laboratory within the scope of our project. The melanization characteristics and mortality rates of the larvae were monitored between 24 and 144 hours after injection. Results: Antibiotic susceptibility profiles were examined; trimetoprim sulfometaxazole and minocycline were susceptible to all isolates, 50% susceptible to ceftazidime, 15% were moderately susceptible and 35% were resistant; levofloxacin and chloramphenicol were found to be 90% sensitive and 10% moderate. It was seen that 90% of the isolates formed strong biofilms and 10% did not form biofilms. In Galleria mellonella infection model, the average larval mortality rate in the first 24 hours was 28.5% and this rate increased to 73% at 144th hours. Conclusion: Galleria mellonella larvae in Stenotrophomonas maltophilia virulence study concluded can be used as model experimental infection. Keywords: Stenotrophomanas maltophilia, virulence factors, Galleria mellonella infection model, model organism