Staphylococcus aureus-induced sepsis in the lobster cockroach Nauphoeta cinerea.

Invertebrates have been instrumental in understanding the mechanisms involved in infectious diseases, considering the idea to replace, reduce and refine the use of mammals as well as to understand the basic principles of immune response in insect. We evaluated the consequences of Staphylococcus aureus-induced sepsis in the last instar nymphs of Nauphoeta cinerea injected with different concentrations of bacteria preserved in two culture media. Infected groups had a decrease in hemolymph metabolites (glucose, amino acids, total proteins, and cholesterol), in contrast to the proteins in the fat body. Higher concentrations of S. aureus caused permanent morphological alterations in adults, decrease in food consumption, increase in isolation, and increase in CFU until death of the cockroaches. Survival and protection of nymphs against a repeated and stronger challenge with the same bacteria varied according to the medium they were conserved. N. cinerea proves to be a suitable and promising model for studies related to bacterial infections.