A 25-year-old male presented with severe urethritis. Over the past 2 days, he had developed fever and chills. Gram stain of the urethral discharge revealed the presence of gram-negative diplococci. The fever and chills are most likely due to the release of excessive amounts of which bacterial component?

In Neisseria, the equivalent to LPS is Lipooligosaccharide (LOS) (c), which consists of lipid A and core oligosaccharide but lacks the O antigen. By triggering an inflammatory response, LOS causes most of the symptoms during Neisseria gonorrhoeae infection. It activates the complement and stimulates the influx of phagocytes leading to the purulent discharge. LOS also contributes to serum resistance, which is an important feature of strains that causes systemic infection. Rapidly growing Neisseria releases outer membrane blebs, which contain LOS. Pili (e) mediate the initial attachment of N. gonorrhoeae to the surface of cervical or urethral epithelial cells. Pili are attached to the cell surface and are not released. The opacity protein (d), which provides N. gonorrhoeae colonies with their opaque appearance, is an outer membrane protein. It mediates binding of N. gonorrhoeae to epithelial cells and plays a role in cell-to-cell signaling. Similar to the pili, the opacity protein is a cell-associated factor. The capsule (a) surrounds pathogenic bacteria and provides them with antiphagocytic properties. However, N. gonorrhoeae is not encapsulated. Exotoxins (b), which are produced by some gram-negative and gram-positive bacteria, bind to specific receptors on the host cells and either alter the function of the host cell or destroy it. N. gonorrhoeae does not produce exotoxin.