Gram (-) Cocci Flashcards Preview

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Flashcards in Gram (-) Cocci Deck (12):

Oxidase positive encapsulated diplococci, growth on Chocolate agar, ferments glucose and maltose, transmitted by respiratory droplets

Neisseria meningitidis


Strain of N. meningitidis that is most common

B strain (NOTE: vaccine contains strains Y, W-135, C, and A. B strain is not immunogenic so no protection would be induced anyway)


Virulence factors of N. meningitidis?

Polysaccharide capsule (detect with latex particle agglutination)

IgA protease (allows colonization in pharynx)

Endotoxin (fever, septic shock)


Deficiency in late complement components (C5-C8) predisposes to bacteremia


What indicates that N. meningitidis infection has spread to blood? What are dangerous complications of fulminant cases of meningitis caused by N. meninigitidis?

- bacteremia indicated by rash

- Waterhouse-Friderichsen syndrome, DIC, shock, coma, death


What are the best ways to diagnose N. meningitidis?

Gram stain of CSF (look for G- diplococci), PCR, latex agglutination to detect capsule


Why are all infants born in the US given erythromycin ointment on their eyes?

Prevention of ophthalmia (N. gonorrhea infection that leads to blindness if untreated)


Oxidase positive diplococci, ferments flucose, growth on chocolate agar, sensitive to drying and cold, sexually transmitted disease

Neisseria gonorrhoeae


Which occurs more commonly, gonorrhea or chlamydia?



What are the pathogenic factors of N. gonorrhoeae?

Pili (attachment), Opa (adherence), IgA protease, invasion of mucosal surfaces to cause inflammation

- all can undergo antigenic variation, which causes antibiotic resistance


Symptoms of a gonorrhea infection

Males: more likely to present, purulent urethral exudate

Females: more likely to be asymptomatic, endocervitis, PID, arthritis


Diplococcus, causes otitis media or sinusitis, normal flora of upper respiratory tract

Moraxella catarrhalis


Top 3 most common causes of otitis media

1) Streptococcus pneumoniae

2) Haemophilus influenzae

3) Moraxella catarrhalis