Microbiology 6 - Gram Negative Cocci We differentiate based on 16S rRNA sequencing; Neisseria sp. - Order Nesseriales - Family Neisseriaceae - Genus Neisseria - Species N.gonorrheae - Important organisms that can infect us in many ways - 10+ different species - Limited virulence of immune-compromised - Gonococcus & meningococcus o Important human pathogens o Meningococcus: They are in the room - 10-15% Characteristics - Non- motile - Gram-negative o Two membrane o Lipopolysaccharides (LPS) Neisseria - lipo-oligosaccharide (fewer sugars) o Thin PG layer o OMPs - Diplococcus Pilus o Two cocci together o Flat sides with division plate porin o 0.6 - 1um - Fastidious growth requirement o Means it's hard to please outer membrane o Aa, purines/pyrimidines, vitamins periplasmic space - 35-37oc. Humid peptidoglycan - Aerobic / capnophilic o require carbon dioxide) plasma membrane o Cultured 5% CO2 - Oxidative positive - Catalase positive Catalase destroys H202 to make H20 + 02 o We make H2O2 to try and defend ourselves against organisms in the respiratory burst o Strong positive - Gonococcus o Variable positive - Meningococcus - Need an energy source; o Glucose - Both o Maltose - Meningococcus LOS lipoprotein
Commensal + (can be) Target epithelium Nasopharynx (upper respiratory tract) Invasive + + (not so invasive) Purulent infection (pus associated with it) Meningococcus + Gonococcus - Genital tract (UTI) + Gram-Negative Envelope Pili (hairs coming out of the diplococci) - Important for pathogenies - Without this they cannot take out - The ones that can stick, have a better focus of infection o Can start to grow - Bind to CD46 - Has a tip - Pil C Sticky bit - Are diverse, can stay one step ahead of the immune system - Change the protein at Pil C - Repeating sub-units at Pil E o Many options for PIl E Allows us to get variation o Antigenic variation · Many antigenically distinct pili (10,000,000+) o Phase variation " Can turn it off and on, have a pili or do not have · Express Pil S instead (is silent) Endotoxin (Lipooligosaccharide LOS) - Neisseria don't have the extra repeating portion, stop at the O portion - Very toxic - Antigenic variation o Core sugars · Low Sialic acid . Makes it look like one of our cells " Avoids destruction " It's really infecting . But can be killed easily o High sialic acid
. Can't be killed by our cells · But not as infecting Protected from serum factors - LOS can be released form the surface in blebs (vesicles) o Carry them away from the main organism Can cause systemic inflammation > death N.meningtidis - MOMPs (major outer membrane proteins) - I - V (decreasing MW) - I, II, III o They are porins o Useful for transportive material - IV o RMP - reduction modifiable proteins - V o Opa Opacity - Porins proteins o Inhibit phagosome maturation " All though the organism is taken up, it's not killed, . the host cells