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Microbiology > Microbiology - Meningitis > Flashcards

Microbiology - Meningitis Flashcards

1
Q

What is meningitis?

A

Inflammation of the meninges (whereas encephalitis is inflammation of the brain).

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2
Q

How does meningitis typically present? (4 main)

A

Headache
Fever
Nuchal Rigidity
Altered Mental Status

Nausea, vomiting, photophobia can also be seen.

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3
Q

What are the three subdivisions of meningitis? Timing?

A

Acute - SX w/in 24 hrs
Subacute - SX w/in days-weeks
Chronic - SX present for > 4 weeks

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4
Q

What is the pathophysiology of meningitis as seen in a) Strep Pneumonia b) Neisseria meningitidis and c) Haemophilus influenza

A

Pneumonia and Neiserria spread by normal flora of nasopharynx which invade bloodstream.

Haemophilus spread by respiratory droplets to nasopharynx.

They all have a polysaccharide capsule (avoid phagocytosis and complement). Infect the choroid plexus (which produces CSF) - SX will be caused by inflammatory response due to LPS/teichoic acids - increased cytokines and chemokines will be released.

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5
Q

What is the pathophysiology of meningitis as seen in Strep agalactiae (Group B Strep - GBS)?

A

(-) cause of meningitis in adults, (+) cause of meningitis in neonates. Colonize genitourinary tract - vaginal carriage is up to 30% in pregnant women. Passed to neonate during birth (MCC of MENINGITIS IN NEONATES)

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6
Q

What is the most common cause of meningitis in neonates? When does early onset disease present vs late onset?

A

Strep. agalactiae (Group B Strep).

Early onset: In first 7 days
Late onset: 1 week to 3 months after birth

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7
Q

What is the pathophysiology of meningitis as seen in Listeria monocytogenes? Where do they replicate?

A

Infection is caused by consuming contaminated food. They replicate in phagocytes.

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8
Q

Who is at risk to get listeria?

A

Pregnant women can pass to their children (in utero or during birth) and immunocompromised (old age, disease, etc - CMI deficient)

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9
Q

What is the presentation of early vs. late onset disease in neonates (Listeria)? Timing of each?

A

Early onset disease (seen in the first 7 days) - the severe form presents with Granulomatosis infantiseptica (abscesses and granulomas) and there is a HIGH MORTALITY RATE.

Late onset disease (appears 1-3 weeks after birth) and the neonate presents with meningitis or meningoencephalitis with septicemia.

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10
Q

How do you diagnose meningitis? What will be increased/decreased in ________?

A

Lumbar puncture is done (blood samples are second best). The CSF should have an INCREASE in the following:

INCREASED:

Pressure
WBC
Protein

DECREASED:

GLUCOSE

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11
Q

What physical SX would help you differentiate meningitis caused by Neisseria meningitidis from other causes?

A

Nonblanching petechial or purpuric rash

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12
Q

What is the treatment for meningitis? General tx? Specific tx?

A

Give empiric antibiotics w/in 60 minutes of presentation to emergency department.

General: START EMPIRIC ANTIBIOTICS IMMEDIATELY!

Specific: 3rd or 4th generation CEPHALOSPORIN (3rd gen - ceftriaxone or cefotaxime - can cross the BBB) + VANCOMYCIN

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13
Q

How does Neisseria meningitidis stain (gram stain)? Is it aerobic or anaerobic?

A

GN Diplococcus. Aerobic

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14
Q

Where is Neisseria meningitidis usually found? How does it spread?

A

Found: common in nasopharynx
Spread: respiratory droplets

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15
Q

Time frame for Neisseria meningitidis?

A

Causes disease in susceptible individual in less than 4 days.

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16
Q

What are Neisserias two virulence factors? (2)

A

Pilli - allow for colonization
Polysaccharide capsule

Note: Think DIPLOCOCCI = 2 cocci = 2 virulence factors and 2 diseases (meningitis and septicemia)

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17
Q

What are the two most common diseases caused by Neisseria meningitidis? (2)

A

Meningitis and Septicemia (meningococcemia)

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18
Q

How do you diagnose N. meningitidis? Skin? Gram Stain?

A

Rash (petechial/purpuric - separates it from other bacteria causing meningitis)
Gram strain - GN diplococcus
Culture and PCR

19
Q

What is the treatment for N. meningitis?

A

3rd or 4th generation cephalosporins.

20
Q

What is the physiology and structure of H. influenzae? Gram stain? Aerobe or anaerobe or facultative anaerobe? Growth factors? (2) Two group names? (2)

A

Gram strain: GN rod (bacillus)
Facultative anaerobe
Growth factor X and V
a) Type B (HiB) b) Nonencapsulated

21
Q

What is the capsule of H. influenza type B?

A

Polyribosyl ribitol phosphate (PRP) capsule

22
Q

Is H. influenza type B part of the normal flora and how is it spread? Is there a vaccine?

A

Not part of normal flora
Spread: Respiratory droplets
Vaccine exists (use PRP capsule)

23
Q

What are the virulence factors of H. influenza Type B? (2)

A
  1. Adhesins - allow for colonization

2. PRP capsule (polysaccharide capsule) - resist phagocytosis

24
Q

What are the most common diseases caused by HiB? (2)

A

Meningitis and epiglottitis

25
Q

How do you diagnose HiB?

A

Gram strain: Gram negative (GN) rod (bacillus)

26
Q

What is the TX for HiB?

A

3rd or 4th generation cephalosporin

27
Q

What is the physiology of nonencapsulated H. influenza ?

A

NO CAPSULE, DUH!

28
Q

Is nonencapsulated H. influenza part of the normal flora and how is it spread?

A

Yes, it is part of the normal flora.

Spread: Respiratory droplets

29
Q

What virulence factors do nonencapsulated H. influenza have? (1)

A

Adhesins - used for colonization

30
Q

What is the physiology and structure of the Leptospira species? Gram strain?

A

Spirochete (with one or both ends having a hook shape)
Grows slowly in culture
NO GRAM STAIN - too thin to see.

31
Q

What is the primary reservoir of Leptospira species?

A

Wild mammals (can also be cats, dogs and livestock)

32
Q

How is Leptospira transmitted?

A

By urine, contaminated water and handling of infected tissue. Farm workers, veterinarians, pet shop owners, meat handlers, people engaged in water sports are at risk.

33
Q

What disease is caused by Leptospira?

A

Leptospirosis

34
Q

What is the incubation period for MILD leptospirosis?

A

1 - 30 days

35
Q

What are the SX of MILD leptospirosis?

A 
Fever
Chills
Headache
Nausea
Vomiting
Abdominal Pain
Myalgia
*may have a rash

CAN LEAD TO MENINGITIS DURING THE IMMUNE PHASE.

36
Q

Does MILD leptospirosis resolve on its own or requires treatment?

A

It spontaneously resolves in 7-10 days but can treat with DOXYCYCLINE or AMPICILLIN.

37
Q

Where can leptospires be found during the first couple of days in MILD leptospirosis? Weeks to years?

A

Days: Blood and CSF.

Weeks to years: Urine

38
Q

Treatment for MILD leptospirosis?

A

Doxycycline or ampicillin

39
Q

What happens in SEVERE leptospirosis (Weil’s syndrome)? Death due to? Diagnosis? Treatment?

A

Rare progression from mild disease.
SX: hemorrhage, jaundice and acute kidney injury
Death: Septic shock with multi-organ failure, severe bleeding
DX: isolation of organism
TX: IV penicillin

40
Q

How are brain abscesses developed?

A
  1. Direct spread from infection (sinusitis, otitis media, mastoiditis, dental infection), can be from 2. hematogenous spread (spread by blood - causing multiple abscesses) and 3. head trauma.
41
Q

Name some bacteria that cause brain abscesses?

A
  1. Streptococcus
  2. Proteus
  3. E. coli
  4. Klebsiella
  5. Bacteroides
  6. Fusobacterium
  7. Staphylococcus

ALL PART OF NORMAL FLORA

42
Q

How do brain abscess patients present?

A

They present with headache, fever and FOCAL NEUROLOGICAL DEFECTS

NOTE: A focal neurological defect –> problem with nerve, spinal cord, or brain function. It affects a specific location, such as the left side of the face, right arm, or even a small area such as the tongue. Speech, vision, and hearing problems are also considered focal neurological deficits.

43
Q

How do you diagnose a brain abscess?

A

MRI

44
Q

What is the treatment for brain abscesses? (2)

A

Drainage of the abscess and empiric antibiotics (3rd or 4th generation cephalosporins)

Microbiology (5 decks)

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