Pneumococcus, meningococcus, GBS Flashcards Preview

Micro/Immuno > Pneumococcus, meningococcus, GBS > Flashcards

Flashcards in Pneumococcus, meningococcus, GBS Deck (24):

Not all Neisseria are; what makes the difference?

pathogenic (aside: meningitidis is facultative intracellular);
1. LOS (aside for quieter inflamm response)
2. IgA protease
3. Meningococcus capsule (gonococcus has pili, porins, Opa!!)


N meningitidis as a pathogen is a

gram neg diplococcus, aerobic/facultative, human-restricted, oxidase-positive, catalase-positive; FERMENTS MALTOSE!!
(aside: airborne droplet transmission and infection resolves without symptoms usually with IgG raised and individuals with natural immunity often by 20)


Growth of N meningitidis is; so use

inhibited on blood agar and overgrown by normal flora on nonselective media;
Thayer-Martin if sampling from mucus membrane (genital, nasopharyngeal), chocolate if NORMALLY-STERILE site (CSF, blood)


Host defends meningitidis with; what can cause complications?

IgG-enhanced complement and PMNs: often effective against meningococcus, usually contains gonococcus;

complement deficiency


_____ gonococcus in women leads to



What can follow DGI/meningococcemia:

septic arthritis (aside is draw joint fluid with gram negatives and culture on chocolate agar), meningitis (aside is draw CSF, maybe gram stain and culture on chocolate), endocarditis


Neonates are protected

from meningococcus by maternal passive, must be protected by prophylactic eye ointment from gonococcus


Test for N meningitidis with

culture and gram stain of appropriate samples; DNA testing is also available

(aside: you can have petechial rash and lead to gangrene; also Waterhouse-Friderichen syndrome with destruction of adrenals, DIC, purpura


What is available to prevent meningo/gonococcus?

Vaccine for former, condoms for latter!!!


How can you treat N meningitidis?

(aside: Penicillin G unless allergic)
Ceftriaxone, cefixime, NOT STEROIDS; admit if complications!!! (aside: give prophylactic rifampin)


For GBS (S agalactiae), give the key features:

1. Encapsulated gram +
2. beta-hemolytic cocci
3. often normal flora
4. seldom pathogenic in previously-healthy adults
(think normal vaginal flora or in GI and upper respiratory tract)


_____ pathogen in neonates regarding GBS, and what do we see?

sepsis with pneumonia early or meningitis late; early disease prevented by INTRAPARTUM IV antibiotics!!


______ pathogen in elderly with ______ regarding GBS; what are some issues?

Opportunistic; predispositions like diabetes and CHF;
think MECA (meningitis, endocarditis, cellulitis, abscess)


Test for GBS by; treat with

gram stain, cAMP factor (S aureus beta-hemolysin can be activated when secreted by GBS), hippurate;
penicillin, amoxicillin, vancomycin (if allergic), surgery!! (PAVS)


For strep pneumoniae, what's the key feature?

Gram +, catalase - diplococci, form chains in culture (aside: form diplococci in chains)


Pneumococcus is the most common cause of; important cause of

community-acquired pneumonia, bacterial meningitis, bacteremia, otitis media; (BOB)
sinusitis, septic arthritis, osteomyelitis, peritonitis, endocarditis (SOPES)


Pneumococcus carriage common in

upper respiratory tract: healthy adult, or vaccinated immunity contains it there


In non-invasive disease of pneumococcus, what is the pathogenesis and how do you diagnose and treat?

Pathogenesis by direct extension into sinuses, eustachian tubes, bronchi (SEB): can cause sinusitis, otitis media, mild pneumonia (diagnose by otoscope and stethoscope, outpatient amoxicillin or cephalosporin), severe pneumonia (diagnose by stethoscope and Xray for lobar consolidation, admit for amoxicillin, fluroquinolones, and/or vancomycin, so do antibiotic sens testing) FAV


Invasive disease pathogenesis for pneumococcus is

hematogenous spread to meninges, joints, heart valves and strong inflammatory response (aside: bimodal distribution, patients 65, immunosuppressed)


Spinal tap findings typical of bacterial meningitis with pneumococcus:

1. Elevated opening pressure
2. Elevated WBC count and neutrophil level
3. Elevated protein
4. Decreased glucose
5. Highly elevated lactic acid
6. Gram stain and culture are POSITIVE unless antibiotic treatment began >4 hrs prior to tap


Initial antibiotics (for invasive disease of pneumococcus) are

vancomycin plus ceftriaxome or cefotaxime (CVC); if antibiotic testing comes back resistant (toxic MIC), add RIFAMPIN, meropenem, or chloramphenicol (MCR)


Steroids may be used for _______

pneumococcus; sparingly early in the antibiotic course, surgical care for septic joints, cellulitis, endocarditis (SEC)


Invasive disease regarding pneumococcus is prevented by

VACCINATION: Prevnar7 recently increased to Prevnar13 and may have to step up again ("replacement disease")


Classic tetrad of meningitis:

Headache, fever, stiff neck, photophobia