Bacterial infx CNS Flashcards Preview

Microbio > Bacterial infx CNS > Flashcards

Flashcards in Bacterial infx CNS Deck (72):
1

What are the two categories of CNS infections?

1. Those involving the meninges (meningitis)
2. Those which are confined to the brain (encephalitis)

2

What is the blood-brain barrier? What are the three functions it provides?

1 Separates blood and CSF
2. Provides physical isolation for the CNS
3. Protects the CNS, but not the PNS

3

What must microbes be able to do to cause CNS infections?

Disrupt the BBB

4

What is the BBB made of?

Tight junctions between endothelial cells and the cerebral microvasculature, cpithelial cells of the chorid plexus, and arachoind cells

5

What two features of the epithelial cells that comprise the BBB make them a good barrier?

1. Tight junctions
2. Little pinocytosis/channels

6

How do CNS infections usually start? (3)

1. Bacteremia or spread from a site adjacent/contiguous with the CNS
2. Direct inoculation (rare)
3. Neuronal spread

7

What are the three categories of meningitis? What are the usual causes of each?

1. Acute pyogenic (bacterial)
2. Aseptic (viral)
3. Chronic (any class)

8

Bacterial meningitis is more or less fatal than viral?

More

9

What are the predisposing factors to pneumococcal meningitis? (2)

Pneumonia and chronic OM

10

What are the predisposing factors to meningococcal meningitis? (2)

1. h/o recent URI (viral)
2. Complement deficiencies

11

Which type of meningitis occurs frequently in complement deficiencies?

Meningococcal

12

Where/when are meningococcal outbreaks (specifically) common?

Schools and military barracks

Winter months

13

What are the two common features of the bacteria that cause meningitis?

1. Capsule
2. Fimbrae/pili

14

What is the function of the capsule of the meningitis-causing bacteria?

Resists immune mechanisms that allows them to travel to the CNS

15

What is the function of the fimbrae/pilli of the meningitis-causing bacteria?

help colonize the CNS cells

16

What are the two main things that cause the damage with meningitis?

1. Toxins
2. Immune response

17

What is the significance of the bacterial toxins?

Incude the production of cytokines

18

What is the function of the cytokines released?

Cause inflammation and edema in the CNS

19

What are the four common symptoms of meningitis?

1. Fever
2. HA
3. Stiff neck
4. AMS

20

How do you diagnose meningitis? (3)

1. Gram stain CSF
2. Cultures
3. Latex agglutination

21

What is the treatment for meningitis? What is this based on?

Empiric abx

Examination of CSF, age, preexisting conditions

22

The majority of cases of bacterial meningitis occur in what population group?

infants and children

23

What is the most (and second most) common pathogen of bacterial meningitis?

1. Strep pneumonia
2. Neisseria meningitidis

24

What percent of meningitis are caused by Strep agalactiae?

5-10%

25

What percent of meningitis are caused by listeria monocytogenes?

5-10%

26

What percent of meningitis are caused by H/influenzae?

5-10%

27

What percent of meningitis are caused by Strep pneumonia?

50%

28

What percent of meningitis are caused by N.meningitidis?

25%

29

Kids less than 2 month of age (or 2 yo) are have bacterial meningitis caused by what pathogen?

Strep agalactiae

30

What are the four major causes of bacterial meningitis in neonates?

1. Strep agalactiae
2. E.coli
3. Gram negative enterics

31

What is the gram stain and morph of strep pneumonia? Catalase?

Gram positive cocci, catalase negative

32

What is the hemolysis patterns seen in strep penumo? Is it optochin sensitive? bile?

alpha

Sensitive to bile and optochin

33

Who are more frequently colonized by strep pneumonia kids or adults?

Kiddos

34

What are the three virulence factors that strep pneumo produces to help them spread in the body?

1. IgA protease
2. Pneumolysin
3. Capsule

35

How fast is the onset of pneumococcal meningitis?

hours

36

How do you diagnose pneumococcal meningitis?

Gram stain CSF
Latex agglutination

37

What does the latex agglutination test detect in pneumococcal meningitis?

Capsular antigens

38

What is the treatment for meningitis?

Initially vanco with a cephalosporin

Later with more targeted

39

How do you prevent pneumococcal meningitis?

Vaccination

40

What does the vaccine against pneumococcal meningitis contain?

Purified capsular polysaccharide from 23 types of pneumococcus

41

Why is the vaccine for pneumococcal meningitis not effective in children?

They have a problem developing antibodies to polysaccharides

42

What are the recommendations for the PPV vaccine?

Adults >65 yo
Persons >2 with chronic illness or likely exposure

43

What is PCV13 used in the pneumococcal vaccine?

Pneumococcal polysaccharide conjugated to nontoxic diphtheria toxin

44

What is the gram stain and morph of Neisseria meningititidis? (**key shape**)

Gram negative diplococci with **coffee bean appearance**

45

What are the two virulence factors for N.Meningitidis?

1. LOS
2. Capsule

46

Coffee/kidney bean appearing bacteria = ?

N. Meningitidis

47

How do you differentiate between N. Meningitidis vs gonorrhea?

Oxidizes both glucose and maltose

48

Is N. Meningitidis oxidase positive? Catalase?

Both positive

49

What type of agar is needed for N. Meningitidis?

Chocolate agar

50

Do we have vaccines against N. Meningitidis?

Four of the five common ones

51

How is N. Meningitidis transmitted?

Coughs, secretions etc

52

What are the serotypes of N. meningitidis most often causes disease? (5) Which one do we not have a vaccine against?

1. C
2. B** no vaccine
3. Y
4. W
5. A

53

What are the significant sequelae of N. Meningitidis infections?

Neuro deficits
Limb amputation

54

What are the symptoms of meningococcal disease besides HA, stiff neck? (3)

Abrupt fever, hypotension, rash

55

How do you diagnose Meningococcal meningitis?

1. gram stain CSF
2. Antigen detection in CSF

56

What percent of patients with only bacteremia caused by meningococcal have detectable organisms in blood smears?

30%

57

What is the treatment for meningococcal meningitis? (initially vs confirmed Meningococcal)

Vanco initially,

Penicillin if confirmed Meningococcal disease

58

What are the two types of vaccine against meningococcal disease? Which is actually used?

tetravalent polysaccharide only used for immune suppressed

(MCV4) Tetravalent polysaccharide conjugate vaccine = actually used

59

How many doses of the vaccine against meningoccal disease ?

one dose in 2-5 years if indicated

60

What is the conjugated polysaccharide that the meningococcal vaccine is conjugated to?

Diptheria toxin subunit

61

Which type of meningitis displays decreased glucose levels in the CSF: bacterial or viral?

bacterial

62

Which type of meningitis displays increased protein levels in the CSF: bacterial or viral?

Bacterial

63

Which type of meningitis displays increased pressure in the CSF: bacterial or viral?

Bacterial

64

Which type of meningitis displays increased levels of mom/lymphocytes: bacterial or viral?

Viral

65

Which type of meningitis displays increased levels PMNs: bacterial or viral?

Bacterial

66

If a pt presents with meningitis, without knowing anything else, what is the most likely cause of it? What is it's a kid <2 yo (or months

Strep Pneumonia

GBS for kiddos

67

What is the gram stain and morphology of listeria?

Gram positive rod

68

What is the gram stain and morphology of HiB?

Gram negative rod

69

What groups of people is Listeria a major factor for meningitis?

Very young and old

70

Bile test is used to differentiate between what pathogens?

Strep and enterococcus

71

What bacteria need chocolate agar?

1. Neiserria
2. Heamophilus

72

Does the MCV4 vaccine against N. Meningiditis work well?

Yes, IgG and goodness