4 Mucosal Immunity and Evasion Strategies of Neisseria gonorrhoeae Mónica Imarai 1 , Claudio Acuña 1 , Alejandro Escobar 2 , Kevin Maisey 1 and Sebastián Reyes-Cerpa 1 1 Department of Biology, Faculty of Chemistry and Biology, Universidad de Santiago de Chile 2 Department of Basic Sciences, Faculty of Dentistry, University of Chile 1,2 Chile 1. Introduction Neisseria gonorrhoeae, the gonococcus, is a gram-negative diplococcus which causes the sexually transmitted disease gonorrhea (Figure 1). The contagious nature of gonococcal infection remains a major global health problem and represents 88 million new cases every year (WHO, 2011). N. gonorrhoeae is transmitted by human to human contact and is highly adapted to the genital tract, surviving poorly outside the human body. However, gonococcus develops resistance to antimicrobials, antigenic variability and mechanisms of immune evasion by which it evades host defenses, thus persisting and often causing undetected asymptomatic infection (Tapsall, 2001). Fig. 1. Neisseria gonorrhoeae. (A) Colonies on agar, (B) Gram-staining, (C) Transmission electron microscopy, (D) Confocal microscopy of the bacteria (in green). www.intechopen.com