Neisseria gonorrhoeae. Neisseria gonorrhoeae is a Gram-negative diplococcus and the etiologic agent that causes the sexually transmitted disease gonorrhea. This obligate human pathogen belongs to the family Neisseriaceae that includes Gram-negative aerobic bacteria from fourteen genera. The genus Neisseria contains two important human pathogens, Neisseria gonorrhoeae and Neisseria meningitidis, the latter being a major cause of septicemia and meningitis. Neisseria gonorrhoeae is an ancient pathogen with biblical references (Leviticus 15:1–19) but was not discovered to be the causative agent of gonorrhea until 1879 by the Polish physician Xxxxxx Xxxxxx Xxxxxxxxx Xxxxxxx (98). Neisseria gonorrhoeae is a heterotrophic organism measuring 0.6 to 1.0 μm in diameter. The gonococcus is microaerophilic, grows optimally at 35-37°C with 3-10% CO2 added to the atmosphere, and requires cysteine, iron, yeast extract, and glucose (55). A facultative aerobic intracellular pathogen, the gonococcus exhibits twitching motility and uses type IV pili to adhere to surfaces. The gonococcus exhibits the ability to be naturally competent for genetic transformation at all phases of growth (20, 69, 183). This frequent uptake of exogenous DNA (i.e. transformation) exhibited by the gonococcus results in a high rate of genetic variation. Transformation and the prevalence of nearly 100 phase variable genes all lead to extensive genome plasticity. Remarkably, the gonococcus has recently demonstrated the ability to acquire human DNA through horizontal gene transfer which is the first evidence of the transfer of genetic material from a human to a bacterial pathogen (9).
Neisseria gonorrhoeae. Neisseria gonorrhoeae is a Gram-negative, aerobic diplococcus and the causative agent of the sexually transmitted infection, gonorrhea. N. gonorrhoeae is one of two important human pathogens belonging to the genus Neisseria, which is comprised of many species that are commensals and pathogens of humans and animals. The other human pathogen, Neisseria meningitidis, is a major cause of meningitis and septicemia. While the earliest references to meningococcal disease date back to the 19th century writings of Vieusseaux, gonorrhea is an ancient disease, with descriptions found as far back as the Old Testament in the Book of Leviticus (61). Gonococcal disease was termed “gonorrhea” by the second century physician Xxxxx from the Greek words “xxxxx” (seed) and “rhia” (flow), in reference to the hallmark discharge observed in male infection; the causative agent, however was not identified until 1879 by the Polish physician Xxxxxx Xxxxxx Seigesmund Neisser (130, 180). Thus, N. gonorrhoeae has been evolving with mankind for thousands of years, allowing ample time for the gonococcus to develop into an efficient human pathogen. Several factors contribute to the success of N. gonorrhoeae as a pathogen. The gonococcus is naturally competent for genetic transformation, allowing frequent uptake of exogenous DNA and thus a high rate of genetic variation by horizontal gene transfer (HGT). Transformation is most efficient from other Neisseria spp. based on the presence of a 10 base pair specific DNA uptake sequence (74). However, there are examples of HGT from other organisms, most remarkably of which is the presence of a fragment of the human nuclear element L1 gene recently identified in approximately 11% of N. gonorrhoeae strains, which also serves as the first example of HGT between humans and a bacterial pathogen (5). In addition, the gonococcus possesses many phase variable genes, which in conjunction with frequent transformation, allows extensive genome plasticity, facilitating adaptation to environmental changes in the host and evasion of the host immune response. N. gonorrhoeae also demonstrates the ability to form biofilms, both in vitro and in vivo, which may contribute to the development of asymptomatic infection in women and provide increased resistance to antimicrobials (99, 234). Furthermore, N. gonorrhoeae has been shown to survive and replicate within neutrophils (262) and possesses a number of mechanisms to resist oxidative stress, antimicrobial agents, and...
Neisseria gonorrhoeae. Neisseria meningitidis ...............................................................................
