Infecto 1 Flashcards
Meningococcus/Enterovirus
Neisseria meningitidis is a commensal of the human _____
Nasopharynx; 10% of the population are colonized
N. meningitidis is a gram _____; encapsulated; oxidase-_____; aerobic/anaerobic; diplococcus
negative; positive; aerobic
What allows for the definition of the 12 serological capsular groups?
Differences in the chemistry of the polysaccharide capsule
MeningoD; Name the 6 serological types responsible for almost all cases of disease:
A; B; C; W; X; Y
Outbreaks are usually caused by multiple strains (T/F)
False; most outbreaks are clonal; caused by single strains
How is N. meningitidis transmitted?
Aerosol droplets and respiratory secretions; cant survive for long in the enviroment
MeningoD; Carriage peaks during _____ (age period)
adolescence and young adulthood
Highest rate of meningococcal disease occurs in: (age)
Infants <1yr; immunologic inexperience
Most cases of meningococcal d. in <1yr are caused by wich strain?
B strain
After 1yr which strain causes meningo d.?
85% are caused by B and C strains; remainder by Y
MeningoC; Disease occurs ____ after acquisition of the pathogen.
1-14d
How does N. meningitidis circumvents secretory IgA?
Invasive bacteria secretes IgA A1 “protease”
Resistance to complement-mediated lyses and phagocytosis is mediated by
Polysaccharide capsule and “lipopolysaccharide”
Most of the tissue damage in meningo d. is caused by
host immune mechanisms activated by meningo d. components (LPS)
Capillary leak syndrome is explained by:
microvascular injury that leads to increased vasc permeability
Main complication of Capillary leak Sd:
Pulmonary edema
Which cytokine has a negative effect on myocardial contractility?
IL-6
N. meningitidis can penetrate the blood-brain barrier (T/F)
True; this is facilitated by pili and possibly Opc (Opsonization protein C)
Cite the two main mechanisms CNS damage occurs by:
Direct meningeal inflammation and indirectly by circulatory collapse
Main neurological cause of death in meningo d.
increased intracranial pressure > herniation
Levels of Serum Bactericidal Antibody are highest and lowest:
Highest at birth and amog adults; lowest between 6m and 2yr
Nonpathogenic Neisseria can elicit natural antibodies (T/F)
True; N. lactamica and others can estimulate antibodies production
MeningoD; Serum bactericidal antibody is ____ dependent
Complement
Complement deficiencies increase menigo d. risk up to:
1000-fold
Monoclonal antibody against complement prot C5
Eculizumab; increases risk of meningo d.
For paroxysmal nocturnal hemoglobinuria & atypical hemolytic uremic Sd
Most common form of meningococcal infection:
Asymptomatic carriage in the nasopharynx
Main presentation of “invasive” meningo d.
Meningitis; 30-50% of cases
Clinical presentations of invasive meningo d. other than meningitis (5)
Bacteremia; meningo septicemia; pneumonia; chronic meningo; occult bacteremia
Describe initial rash in meningo d.
Maculopapular; indistinguishable from viral rashes; 10% of cases
MeningoD; Rash that develops in 80% of cases:
Nonblanching or petechial rash
Fulminant meningo d. skin lesion:
prominent petechiae and “purpura”; also known as purpura fulminans
Most children <5yrs report headache during meningo meningitis (T/F)
False; most infants do not report headache
Seizures occurs less frequently in meningitis by meningococcus (T/F)
True; seizures more common in pneumococcus and haemophilus b
Serotype that can cause a meningo”encephalitis” like case:
Group A
Simptoms of “chronic” meningococcemia: (6)
fever; nontoxic appearance; arthralgia; headache; splenomegaly; maculopapular petechial rash
Mean duration of chronic meningo:
6-8 wks; cultures may be sterile; sulfonamide therapy is a risk factor
First line of ATB for suspected menigo d.
Third gen Cephalosporin (Ceftriax)
Offers protection against pneumococcus and H. influenzae
Meningo D; When should vancomycin shold be considered as aditional ATB?
Local high rate of B-lactam-resistant pneumococcus
Necrotic skin lesions are less frequent when this ATB is used
Ceftriaxone
Meningococcal disease; Recommended treatment duration
5-7 days
Decreased susceptibility to penicillin in meningo d. is caused by:
Altered penicillin-binding protein 2; doesn’t seem to affect response to therapy
Because of pulmonary edema; ETI is recommended after
40ml/kg with compensated shock; reduces work of breathing
CTC are recommended in meningo meningitis (T/F)
False; alhough used in meningitis by h influenzae; no data supports use in meningo .d
Which viral infection usually reactivates during meningo infection?
Latent herpes simplex
Immune complex vaculitis may occur at wich point of meningo .d
First 10 days
Most commmon complication of severe meningo septicemia
Focal skin infarction; typically lower limbs
Most frequent neurologic sequela of meningo meningitis
Deafness; 5-10%
MeningoD; Profilaxis is indicated for:
Close contacts; contact with oral secretions