Haemophilus, Neisseria and Fastidious gram-Negatives: Meningitis and Bites

Question 1

name two bacteria that can cause meningitis?

Answer 1

haemophilus influenzae and neisseria meningitidis

Question 2

define meninges

Answer 2

three connective tissue layers in the CNS. pia mater, arachnoid, and dura mater. support blood vessels and contain CSF mostly in subarachnoid space

Question 3

define meningitis. is it always due to infection?

Answer 3

inflammation of the meninges. usually but not always, can also have malignant or neoplastic meningitis and autoimmune

Question 4

what two other disease are associated with meningitis?

Answer 4

meningoencephalitis (parenchymal involvement) and encephalitis (predominantly disease of brain tissue)

Question 5

describe the pathogenesis of meningitis

Answer 5

bacteria in CNS and bacterial products leads to an inflammatory response of neutrophils and cytokine release. these result in injury to the BBB which leads to edema, elevated ICP, metabolic and toxic disturbances. immune response also leads to vaso-dilation and constriction which leads to more edema, elevated ICP, local ischemia, necrosis, and hydrocephalus

Question 6

name some symptoms of meningitis

Answer 6

systemic-fever, vomiting
local-headache stiff neck
organ related-photophobia, confusion, coma, somnolence, seizures.

Question 7

name some signs of meningitis

Answer 7

systemic-fever
local- meningismus (meniges are sensitive to stretch) i.e. headache, stiff neck, positive Kernig and Brudzinski signs
organ related- cranial nerve abnormal findings, signs of elevated CNS pressure, altered mental status

Question 8

describe 3 cases in which the typical signs and symptoms of meningitis may not be seen

Answer 8

newborns, older patients (no fever, just acute altered mental status), neutropenic and other immunocompromised patients.

Question 9

what factors will cause you to perform or not perform a STAT lumbar puncture with a clinical suspicion of meningitis? 7

Answer 9

immunocompromise, history of CNS disease, new-onset seizure, papilledema, altered state of consciousness, focal neurologic deficit (i.e. paresis, weakness in left or right arm), delay in performance of diagnostic lumbar puncture.

Question 10

What CSF lab results indicate a high risk for bacteria meningitis?

Answer 10

high leukocytes >1000, high neutrophils >85-95%, high protein count >100-150, low glucose serum <40%, 85% smear-positive

Question 11

describe the microbiology of bac meningitis in newborns, infants, children, and adults

Answer 11

1-group B streptococci, E. coli, Listeria
2-Neisseria meningitidis, Haemophilus influenzae, streptococcus pneumoniae
3-N. meningitidis, S. pneumoniae
4- S. pneumoniae, N. meningitidis

Question 12

name the sequelae of meningitis

Answer 12

hearing loss, vision loss, ataxia, stroke or spinal infection, hemi or quadraparesis, diabetes insipisus, hydrocephalus, intellectual and behavioral deficits

Question 13

Describe the biology of Haemophilus Influenzae

Answer 13

gram-negative coccobacilli, blood loving, requires X (heme) and V (NAD) factors for growth.

Question 14

which strain of H. influenzae is a major invasive human pathogen? what diseases can it cause? (5)

Answer 14

capsule type b (polyribitol ribose phosphate, PRP) strains. meningitis, epiglottitis, pneumonia and empyema (suppurative infection of sleural space), cellulitis, septic arthritis

Question 15

what is a bacterial capsule?

Answer 15

polysaccharide or polypeptide layer outside cell wall, usually has antiphagocytic and or other immunomodulatory properties

Question 16

what diseases can non-encapsulated H. influenzae cause?

Answer 16

otitis media, pneumonia, sinusitis, exacerbation of COPD

Question 17

describe the epidemiology of H. influenzae. where is it found? when is carriage common, genetic history

Answer 17

it’s found in humans only, carriage occurs a few days after birth, group b is clonal (i.e. derived from a single ancestor)

Question 18

What type of vaccine is H. Influenzae group b (Hib)

Answer 18

is a conjugate to protein antigen; because polysaccharide weren’t had beneficial for children the higher risk group.

Question 19

what is the drug of choice for H. influenzae infections. What abt for PCN-allergic? what else is used for decreasing sequelae?

Answer 19

ceftriaxone; chloramphenicol if PCN-allergic; dexamethasone

Question 20

describe the biology of neiserria meningitidis

Answer 20

aka meningococcus, gram-negative diplococci (slightly flattened, kidney bean shape), grows on chocolate (aka blood+RBC content) agar, prefers CO2

Question 21

What should be kept in mind when obtaining a Neisseria meningitidis?

Answer 21

specimen is highly susceptible to cold, high pH, and drying, must get to lab quickly.

Question 22

which portion of the immune system is important in immunity against Neiserria meningitidis?

Answer 22

complement

Question 23

describe the epidemiology of N. meningitidis. how does it spread, carrier, is it seasonal, rate in children and developing countries,

Answer 23

respiratory pathogen (spread via aerosol route), carrier state is frequent, highest in Feb-Mar, lowest in Sept, rate is 10x higher in children <2 y/o (day care is risk factor), higher rates in less-well developed nations (i.e. African meningitis belt).

Question 24

Name some diseases caused by meningococcus 3

Answer 24

meningitis and acute meningococcemia, chronic meningococcemia (fever, petechiae, dermatitis, artritis), note: pneumonia is unusual. also not primary cause of pharyngitis

Question 25

describe the pace, severity, and triad seen in meningococcal meningitis seen with acute septicemia.

Answer 25

• rapid (symptoms seen 12-15 hrs after disease onset)
• vry high mortality
• headache, confusion, and stiff neck in less than half of patients

Question 26

what are some other things to look for in meningococcal meningitis?

Answer 26

upper respiratory symptoms, myagias, petechial and purpuric rashes (>50%), shock, DIC, waterhouse-friderichsen syndrome

Question 27

what vaccines are available for meningococcal diseases? which group is not covered under this vaccine?

Answer 27

polysaccharide vaccine (ages 2-10 and >55)
conjugate vaccine (for everyone else)
does work with serogroup B

Question 28

what drug is used for chemoprophylaxis treatment of meningococcal meningitis?

Answer 28

rifampin 1st; ciprofloxacin, ceftriaxone

give within 24hrs of contact

Question 29

name common bacteria found in cat, dog, and human bites

Answer 29

cats/dogs-pasteurella multocida (agressive cellulitis and sepsis)
human-eikenella corrodens
dogs- capnocytophaga canimorsus-sepsis in P. with liver disease and asplenia