Klebsiella pneumoniae is a gram-negative bacillus commonly isolated from nosocomial pneumonia patients. Given the increasing development of strategies to bypass the therapeutic molecules used today, the development of an immunoprophylactic safe approach against the pathogen is of great clinical relevance. Here we employed the strain of Klebsiella pneumoniae ATCC BAA1706 for the intradermal Immunization of Balb/c mice. Two weeks after three immunizations the mice were intratracheally challenged with 3x108 or 1,5x106 CFUs of K. pneumoniae and euthanized 24h post-infection. We did not detect changes in the peripheral blood cell numbers. However, the infection with 3x108 CFUs of K. pneumoniae led to an increase in the neutrophil count on the bronchoalveolar lavage. The immunization protocol used in this study led to production of IgG serum titers of IgG1 and IgG2a subclasses against the bacterial antigens. Our results exhibited that the intradermal immunization with heat killed K. pneumoniae ATCC BAA1706 led to the activation of the humoral acquired immunity, which has been previously proved participant in K. pneumoniae infections depuration.

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