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Lung Klebsiella pneumoniae infection in anti-LPS protected and unprotected mice - Survival, bacterial load and histopathological differences

Aim: The purpose of this work was to examine the effect of anti-LPS monoclonal antibody activity in mice intranasaly challenged with a lethal dose of Klebsiella pneumoniae (K. pneumoniae). Method: In our experiments we used BALB/CN mice eight to twelve weeks old. The animals were separated in two groups. One group received 1 mg per animal of anti-LPS monoclonal antibodies and other received saline intraperitoneally 4 hours prior to infection. We used anti-LPS monoclonal antibodies that were previously shown to be highly specific for O1 LPS of K. pneumoniae. The animals were infected with a lethal dose of K. pneumoniae Caroli O1:K2 (2, 6x102 CFU). The efficacy of monoclonal antibodies was determined by the survival study and by comparison of lungs colony counts and histopathological changes between two groups 24 and 48 hours after the infection. Results: Our study has shown that pre-treatment of animals with anti-LPS monoclonal antibodies resulted in 33 % survival compared to unprotected animals that all died within 4 days. Besides the survival we also found different lung bacterial loads between two groups. Sections of the lungs obtained from the protected mice 24 and 48 hours after the infection showed lower degree of inflammation compared to unprotected group. Conclusions: The anti-LPS monoclonal antibodies have shown to be protective in a lung model of K. pneumoniae infection. They reduced the bacterial loads in lung tissues of protected animals and histopathological changes compared to unprotected mice.

Klebsiella pneumoniae; antilipopolysaccharide immunity; intranasal infection

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