Methods for Studying Neisseria meningitidisBiofilms
Neisseria meningitidisis an organism whose environmental niche is limited to the human host. It can frequently colonize the human nasopharynx and has the ability to cause severe systemic infections. These infections can be sporadic, endemic or occur in ou
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1. Introduction Biofilm research has gained considerable attention in the last 10–15 years. A biofilm is a community of microorganisms attached to a surface and encased in an exopolymeric matrix. Biofilms are formed under conditions of environmental stress and are often associated with shear forces. The members of the biofilm are afforded more protection from environmental factors than, if they were, in an individual planktonic state. These include protection from antimicrobials, osmolarity fluctuation, predation, UV light, reactive oxygen species, and dehydration (1). A model organism for biofilm development is Pseudomonas aeruginosa, which forms biofilms in the lungs of cystic fibrosis patients. Biofilm formation occurs in five stages for this organism and these stages are generally applicable to other biofilm-forming organisms: (1) Loose association of the bacterium with a surface; (2) tight bacterial adherence and transcriptional changes to adapt to the new environment; (3) bacterial aggregation and microcolony formation as defined by a small number
Myron Christodoulides (ed.), Neisseria meningitidis: Advanced Methods and Protocols, Methods in Molecular Biology, vol. 799, DOI 10.1007/978-1-61779-346-2_11, © Springer Science+Business Media, LLC 2012
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of bacteria encased in a matrix; (4) mature biofilm development, often seen as mats or tall structures that have channels to disperse nutrients to all the bacteria; (5) detachment of bacteria from the biofilm to colonize other locations (1). Neisseria spp. are obligate human pathogens and commensal organisms. The nasopharyngeal flora members, N. meningitidis and Neisseria lactamica, are able to colonize human hosts for long periods of time without causing obvious symptomatic disease (2, 3). This requires evasion of both innate and adaptive immune defense mechanisms. Neisseria gonorrhoeae is the etiologic cause of the sexually transmitted disease, gonorrhoeae. In men, gonococcal infection results in acute urethritis, 2–5 days postinfection, whereas in women, infection is often asymptomatic. The undetected infection can ascend the female genital tract and cause more serious infections such as pelvic inflammatory disease, which can lead to sterility. The ascending infection can also escape the female reproductive tract to cause disseminated gonococcal infection (4). The ability of the gonococcus to remain undetected in women led to speculation that N. gonorrhoeae was persisting as a biofilm. Gonococcal biofilms can form on cervical tissue ex vivo and persist up to 8 days without obvious damage to the cervical tissue (5). These biofilms can also be maintained in a flow cell on a glass surface (5). Gonococcal biofilms have been demonstrated in vivo, including on in-dwelling intrauterine devices of women with reproductive tract infections (6). Electron micrographs of gonococcal or meningococcal biofilms show the presence of long membrane-like structures throughout biofilms grown in vitro on glass or on cervical tissue culture cells in flo
