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Micro Exam 5 > Lecture 61 Bacterial Meningitis > Flashcards

Lecture 61 Bacterial Meningitis Flashcards

1
Q

Name the primary bacteria involved with meningitis

A 
Haemophilus influenzae
Listeria monocytogenes
Neisseria meningitidis
Streptococcus agalactiae
Streptococcus pneumoniae
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2
Q

Bacterial meningitis has highest incidence rate in what groups?

A

Newborns and elderly

Developing countries

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3
Q

Community vs hospital acquired bacterial meningitis

A

Community acquired must be able to infect respiratory tract: S. pneumoniae, H. influenzae, N. meningitidis

Hospital: after iatrogenic procedures, include gram (-) rods, S. aureus, other Strep and Staph

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4
Q

Pathogenesis of bacterial meningitis

A

Infect mucosa –> enter blood –> penetrate BBB –> release inflammatory cytokines –> WBC diapedesis into CSF –> increase permeability of BBB –> Exudates and serum into brain => Edema, intracranial pressure, altered blood flow

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5
Q

Classic triad of symptoms for bacterial meningitis

A

Fever
Excruciating headache
Neck stiffness

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6
Q

Other symptoms for bacterial meningitis

A

Nausea, vomiting, confusion, irritability, delirium, sleepiness

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7
Q

H. influenza seasonality and age of incidence

A

Late winter, early spring

Infants 7-18 months

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8
Q

N. meningitidis seasonality and age of incidence

A

Winter

Infants and children 1 month to 19 years

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9
Q

S. pneumoniae seasonality and age of incidence

A

Winter
Infants and children 1 month to 4 years
Elderly

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10
Q

S. agalactiae seasonality and age of incidence

A

Winter

Neonates

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11
Q

Listeria monocytogenes seasonality and age of incidence

A

Summer

Newborns and predisposed adults

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12
Q

General diagnosis and treatment of bacterial meningitis

A

Many studies can be useful, but CSF analysis is most

Initiate treatment quickly if any sign of potential infection

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13
Q

Signs of neonatal meningitis

A

Hyperthermia (or hypothermia when close to death)
CNS manifestations: lethargy, seizures, irritability
GI: vomiting, diarrhea, anorexia, distension
Respiratory: dyspnea, apnea, cyanosis
Bulging fontanelle
Hypotonia

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14
Q

Primary bacteria that cause neonatal meningitis

A

S. agalactiae (most common)
E. coli
Listeria monocytogenes

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15
Q

Early vs late Neonatal Group B Strep

A

Early: within first 5 days, Ob complications common, bacteremia, pneumonia, meningitis

Late: 7 days – 3 months, Ob complications uncommon, bone/joint infections, bacteremia and fulminant meningitis

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16
Q

Other name for GBS (group B Strep)

A

Strep agalactiae

17
Q

Diagnosis of S. agalactiae

A

Presumptive tests: CAMP factor looking at hemolysis, DNA probe

Definitive: isolation from infected site

18
Q

E. coli and meningitis

A

Important in neonatal, but rare in adults–only after surgery that introduced bacteria
Encapsulated K1 strains, g(-)

19
Q

Listeria monocytogens general characteristics

A

Gram (+) motile coccobacillus
Tumbling motility
Facultative intracellular–epithelial cells and macrophages

20
Q

Listeria monocytogenes virulence factors

A 
LPS-like surface component: inhibits phagocytosis
Listeriolysin O (LLO): disrupts phagolysosome membrane, inhibits antigen processing, induces apoptosis
21
Q

Listeriosis clinical manifestations

A

Neonates: if acquired in utero => death or pneumonia, seizures, skin lesions

Adults: leading cause of meningitis in cancer and renal transplant patients, brain stem encephalitis is classic feature

22
Q

Haemophilus influenzae general characteristics

A

Also called HIB
Gram (-), non-motile coccobacillus
With or without a capsule
Has Lipooligosaccharide in cell wall (LOS)
Requires RBC factors for growth but isn’t hemolytic
Considered normal flora in 80%

23
Q

Haemophilus influenzae virulence factors

A 
LOS
PRP: prevents killing by PMN's
Nueraminidase
IgA protease
Fimbriae: attaching to nasopharynx
24
Q

Common onset of HIB meningitis

A

Usually mild URI or otitis media several days before

Followed by deterioration and signs of meningitis

25
Q

Pathogenesis of HIB meningitis

A

Infects respiratory epithelium
Penetrates epithelium
Enters blood and lymph
Spreads to CSF

Non-encapsulated strains have adhesins that allow attachment to mucins on ciliated cells

Causes loss of cilia, inflammation, and sloughing of damaged cells from action of LOS

26
Q

Treatment of HIB meningitis

A

beta-lactams like amoxicillin/clavulanic acid

Or cephalosporins

27
Q

Prevention of HIB

A

Vaccines

28
Q

Strep pneumoniae general characteristics

A

Gram (+), lancet shaped diplococcus
Alpha-hemolytic–greenish colonies
Optochin sensitivity
Encapsulated strains are virulent

Occurs more often in colder and wetter months
Young children and adults over 65
Viral infections => inc risk of pneumococcal pneumonias
Organism is aspirated

29
Q

Pneumococcal meningitis may follow?

A

May follow pneumococcal pneumonia or infections elsewhere in the body

30
Q

What is the most common agent in recurrent meningeal infections?

A

S. pneumoniae

31
Q

Pneumococcus virulence factors

A

IgA protease, H2O2, Pili
Peptidoglycan-teichoic acid complex–g(+)
Capsule
Autolysin–lyses itself to release pneumolysin in effort to dampen immune response
Pneumolysin–causes pores to form in target cell membrane => apoptosis, activates complement

32
Q

S. pneumoniae diagnosis

A

Optochin sensitivity

Bile solubility test

33
Q

S. pneumoniae treatment and prevention

A

Penicillin G
Fluorquinolones, vancomycin, linezolid

Vaccines exist and are recommended for elderly

34
Q

Meningococcal meningitis general

A 
Caused by Neisseria meningitidis
Often in dorms and military recruits
Gram (-)
Kidney bean shaped diplococcus
Encapsulated
Serogroupds A,B,C,Y,W135
Acute meningococcemia=>meningitis
35
Q

Meningococcal meningitis epidemiology

A

Humans only reservoir
Close contact required
Colonizes nasopharymx

36
Q

Meningococcal meningitis manifestations

A

Presence of non-blanching rash–petichiea and pink macules

37
Q

Meningococcal meningitis diagnosis

A

Gram stain CSF
Culture on chocolate agar, Thayer-Martin agar
Capsular polysaccharide in CSF

38
Q

Meningococcal meningitis treatment

A

Penicillin G

Vaccine now available for all serotypes

Micro Exam 5 (8 decks)

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