gram negative cocci

Question 1

moraxella catarrhalis: character

Answer 1

oxidase positive, gram negative cocci

upper respiratory tract normal flora

Question 2

moraxella cataarhalis: clinical presentations

Answer 2

chest infections in patients with predisposing conditions: pneumonia

Question 3

moraxella catarrhalis: treatment

Answer 3

co-amoxiclav

Question 4

neisseria gonorrhoeae: histology + character

Answer 4

gram negative intracellular diplococci (in polymorphonuclear leukocytes)

oxidase positive glucose fermenting

carriage in urogenital sites, rectum and throat

Question 5

neisseria gonorrhoeae: culture

Answer 5

cultured on chocolate agar; normal culture has too many contaminants from commensals

Question 6

neisseria gonorrhoeae: transmission

Answer 6

sexually transmitted disease

Question 7

neisseria gonorrhoeae: virulence factors

Answer 7

lipooligosaccharide (endotoxin released by gram negative bacteria from the outer cell membrane) - elicits systemic immune response
fimbriae
other outer membrane proteins

Question 8

neisseria gonorrhoeae:

diagnosis

Answer 8

male: discharge/swab from urethra/throat/rectum
female: discharge/swab from urethra, endocervix, lower vaginal, throat, rectum

tests: culture, antigen detection, molecular diagnosis
* n. gonorrohoeae is extremely delicate and requires charcoal transport medium and chocolate agar
* check for other stds in the presence of gonorhoeae

Question 9

neisseria gonorrhoeae: clinical presentations

Answer 9

males - acute urethritis (discharge, dysuria, urethral stricture with repeated infections)
females - often asymptomatic carriae in endocervical canal; may result in ascending infections:
acute salpingitis, pelvic inflammatory disease, fitz-hugh-curtis syndrome (perihepatitis - inflammation around the liver)

in either gender: entry to blood resulting in disseminated gonococcal infection, periorbital cellulitis, pharyngitis

in prepubertal girls and postmenopausal women - vulvovaginitis

gonococcal conjunctivitis in neonates (ophthalmia neonatorum)

Question 10

neisseria gonorrhoeae: treatment

Answer 10

ceftriaxone (most strains are resistant to penicillin and ciprofloxacin)

azithromycin (has increasing. ceftriaxone resistance, and to tackle chlamydia (another sti) if present)

Question 11

neisseria gonorrhoeae: prevention

Answer 11

condom usage

prophylactic silver nitrate/antibiotic eyedrops for neonates

Question 12

neisseria mengiditis: histology + character

Answer 12

gram negative intracellular diplococci found in polymorphonuclear leukocytes

oxidase positive, glucose and maltose fermenting

carriage in the nasopharynx

Question 13

neisseria meningiditis: transmission

Answer 13

close contact (kissing) / respiratory droplets

Question 14

neisseria meningiditis: virulence factors

Answer 14

lipooligosaccharide (endotoxin, elicits systemic immune response system)
anti-phagocytic capsule: groups A B C Y W-135

Question 15

neisseria meningiditis: clinical presentations

Answer 15

meningococcaemia (when meningococcus enters the bloodstream, may progress to severe state of fulminant meningococcaemia, SIRS)
^complications: meningococcal rash (non blanching, petechiae - purpura - ecchymoses on skin and conjunctivae) & waterhouse-friderichsen syndrome (haemorrhagic adrenalitis)

meningitis (when meningococcus seeds directly to the meninges)

uncommon presentations: pneumonia, pericarditis, endocarditism, conjunctivitis, arthritis, chronic meningococcaemia

*meningitis belt: Africa

Question 16

neisseria meningiditis: diagnosis

Answer 16

direct gram stain of CSF
blood (+CSF +throat swab) cultures
molecular diagnosis

Question 17

neisseria meningiditis: treatment

Answer 17

ceftriaxone (clears throat carriage)

benzylpenicillin (does not clear throat carriage)

Question 18

neisseria meningiditis: prevention

Answer 18

prophylaxis: ceftriaxone, rifampicin or ciprofloxacin

Question 19

neisseria meningiditis: vaccination

Answer 19

quadrivalent polysaccharide vaccines for serogroups A C Y W-135 (not useful for infants)

tetravalent polysaccharide vaccines for serogroups A C Y W-135

*no vaccines for serogroup B as it resemble self antigen, even though it accounts for 80% of the cases