L16: Meningitis Flashcards by Jeri Sheldon (AZ PA Mast 20)

Meningitis is infection of the

subarachnoid space

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higher incidence of meningitis

infants, elderly, developing countries

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pathogens considered community acquired meningitis (3)

S Pneumoniae
H influenzae
N meningitidis
normally able to colonize respiratory tract

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pathogens considered hospital acquired meningitis

G- rods
S aureus
other strep and staph
iatrogenic procedures, immunocompromised

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3 pathways to gain access to the CNS

Invasion of bloodstream and seeding of CNS (most common)
Retrograde neuronal pathway (ex Naegleria)
Direct contagious spread: infection, congenital malformation, trauma

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Meningitis presentation

Triad: Fever+Headache+Neck stiffness

+/- N/V, sleepiness, confusion, irritability, delirium

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Encephalitis is

inflammation of the parenchyma

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increases the permeability of the blood brain barrier

release of inflammatory cytokines→ WBC diapedesis into CSF

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Neonatal factors that predispose for meningitis

immaturity of host defense mechanisms or organ systems, low birth weight

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Maternal factors that predispose for meningitis

premature rupture of membranes, urogenital infection during late term, intrauterine infection during early term, invasion of the uterine space

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3 causative agents of neonatal meningitis

Strep agalactiae
E coli
Listeria monocytogenes

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Presentation of neonatal meningitis

Bulging fontanelle, high pitched cry, hypotonia, paradoxical irritability (crying when held)

Other:
Hyperthermia (more common, could be hypothermic), V/D/A, distention, lethargy, irritability, seizures, dyspnea/apnea, cyanosis

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Prevention of neonatal meningitis

Universal prenatal screening for vaginal/rectal colonization with group B strep at 35-37 weeks gestation

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if the mother is (+) for group B strep

antibiotic prophylaxis unless:

C-section planned
Membranes have ruptured/labor begun

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Strep agalactiae morphology

G+ coccus

Capsular polysaccharide

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Strep agalactiae produces

Hyaluronidase
Collagenase
Hemolysin

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Strep agalactiae occurs during ____ in ____

Winter, neonates and adults

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Strep agalactiae in neonates is usually transmitted

during delivery

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Early onset Strep agalactiae symptoms

maternal obstetric complications, symptoms during first 5 days of life.
Bacteremia, pneumonia, meningitis.

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Late onset Strep agalactiae symptoms

maternal obstetric complications uncommon. Symptoms develop 7 days-3 months of age.
Bone/joint infections, bacteremia with concomitant/fulminant meningitis

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Labs for Strep agalactiae

(+) CAMP factor: accentuation of hemolysis due to interaction w/staph beta lysin

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Culture of Strep agalactiae

Isolate organism from:
1. Normally sterile areas: CSF, blood→ definitive
2. Mixed flora areas: vagina, skin
Gray-white colonies with a narrow zone of beta-hemolysis

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Accuprobe can detect

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Strep agalactiae

Listeria monocytogene

E coli morphology

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G- enteric bacillus

Encapsulated K1 strains

who/how get E coli meningitis

Rectal colonization of mother’s vagina NOT an endogenous infection Rare in adults, can follow neurosurgical trauma

Most common bacterial cause. Most common cause in recurrent infections.

Streptococcus Pneumoniae

Streptococcus Pneumoniae presentation

Acute purulent meningitis may follow pneumococcal pneumonia, infection at other site, or appear with no antecedent infection

Streptococcus Pneumoniae risk

Risk: All ages, elderly. Multiple myeloma, sickle cell, cardiorespiratory disease, congenital defects

Streptococcus Pneumoniae occurs in the ____ in _____

Winter, infant, children, adults (elderly)

Haemophilus influenzae morphology

Nonmotile, G- coccobacillus | Lipooligosaccharide (LOS)

Haemophilus influenzae presentation

Prior URI/otitis media → deterioration, meningitis

Haemophilus influenzae occurs in the _____ in ____

Hib: later winter/early spring, infants

Listeria monocytogene morphology

G+ motile coccobacillus | Numerous serotypes, 3 in most cases

Listeria monocytogene is a _______

Facultative intracellular pathogen: in epithelial cells, macrophages, monocytes

Listeria monocytogene virulence factors

LPS like surface component: antiphagocytic. → induces complement dependent hemolytic antibodies Listeriolysin O: disrupts the phagolysosome membrane, inhibits antigen processing, induces apoptosis

the one pathogen more common in summer

Listeria monocytogene

Listeria monocytogene is seen in the _____ and _____

summer, newborns and predisposed adults

Listeria monocytogene sources

Worldwide, plants, soil, feces, vegetable and animal food sources Human and animal carriers

Listeria monocytogene presentation in a normal patient

eliminated by immune system

Listeria monocytogene presentation in an immunocompromised patient

intra and extracellular multiplication → systemic disease cancer/renal transplant→ leading cause of meningitis→ brain stem encephalitis

Listeria monocytogene can cause

Sepsis or meningitis

Listeria monocytogene in utero

tillbirth, abortion, death OR pneumonia, seizures, skin lesions→ high mortality if undiagnosed

Listeria monocytogene from mother’s genital tract

neonatal meningitis

culturing Listeria monocytogene

Requires reduced oxygen tension for in vitro growth Nonfastidious, grows from 0-50 C Pleomorphic, grown on blood agar → 60% of meningitis cases are negative → Tissues must be homogenized before culture

“Tumbling” motility in hanging drop preparation

Listeria monocytogene

meningococcal means

Neisseria meningitidis

Neisseria meningitidis morphology

G-, kidney bean shaped diplococci Encapsulated Disease causing serotypes: A, B, C, Y, W135

most important serotype of Neisseria meningitidis

Trumemba prevents

Neisseria meningitidis (in everyone)

Neisseria meningitidis reservoir

Human reservoir Asymptomatic/slightly symptomatic nasopharyngeal carriers: Chronic, Immune, Nonimmune Infection by close contact

Neisseria meningitidis is seen during the _____ in _____

winter, infants/children

Skin rash: widespread petechiae, pink macules within hour | +/- DIC, G- shock

Neisseria meningitidis

Neisseria meningitidis presentation

``` Transient bacteremia+fever→ spontaneous resolution in 1-2 days Acute meningococcemia (rash)→ meningitis ```

how Neisseria meningitidis causes disease

1. Entry through oropharynx 2. Spread through blood (hematogenous) 3. Diseases: meningitis or other sites 4. Exit through oropharynx

Neisseria meningitidis at home diagnostics

Tumbler test: press a glass tumbler to rash: 1. Does not change color → contact doctor: meningitis 2. Fades/loses color under pressure→ unlikely to be meningitis

Neisseria meningitidis culture/detection

Gram stain CSF Culture: blood, CSF Detect capsular polysaccharide in CSF

agars for Neisseria meningitidis

Fastidious, culture blood, CSF: chocolate agar Thayer-martin agar: Mueller Hinton supplemented with sheep RBC, abx: vancomycin, colistin, nystatin, bactrim

L16: Meningitis Flashcards

(57 cards)