Alfalfa infection model: is it a potential alternative for mouse pneumonia model to study pathogenesis of Stenotrophomonas maltophilia?

The objective of this study was to develop a new, inexpensive and simple plant model to study the virulence potential of Stenotrophomonas maltophilia. The alfalfa seedlings were visually monitored for disease symptoms till 7 days post infection with 10(5) cfu/ml of five different strains (Sm1-Sm5) of S. maltophilia. Symptoms including yellowing of leaves, stunted roots, and brown necrotic regions on seedlings were considered as disease symptoms. Sm5 and Sm2 appeared to be most virulent in alfalfa infection model, whereas Sm3 and Sm4 were moderately virulent. Strain Sm1 was found to be weakly virulent. A comparison of alfalfa infection model was carried out with mouse pneumonia model to compare the virulence of different strains of S. maltophilia in both models. Although there was variability in the level of infection caused by different strains, in both models of study, strains Sm5 and Sm2 appeared to be most virulent and were able to cause a comparatively more severe infection. We conclude that both the models can be used to study the pathogenesis of S. maltophilia and to analyze the preliminary virulence potential of this bacterium. However, clearly, to study the virulence factors, a mouse pneumonia model would be desirable.