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Neuropysch > Bacterial infection CNS > Flashcards

Bacterial infection CNS Flashcards

1
Q

Meninges

Three membranes enclosing the brain and the spinal cord, comprising the dura mater, the pia mater, and the arachnoid membrane.

The _____and _____ can become inflamed during bacterial meningitis, causing complications that may be life-threatening.

A

pia mater and the arachnoid

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2
Q

Primary pathogens in bacterial meningitis

A

Group B Streptococcus (baby)

Streptococcus pneumoniae

Neisseria meningitidis (teens/college)

Haemophilus influenza (unvaccinated)

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3
Q

Occasional pathogens seen in bacterial meningitis

A

Occasional pathogens

Listeria monocytogenes (> 50 years of age)

Escherichia coli and other Enterobacteriaceae

Staphylococcus aureus

Nocardia

Mycobacterium tuberculosis (AIDS associated)

Borrelia burgdorferi, Leptospira , Treponema pallidum

Brucella

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4
Q

Brain damage during meningitis is mostly attributable to :

Bacteria like Streptococcus pneumoniae activate ______ that release proteolytic enzymes and reactive oxygen species that can damage host tissue

A

the side effects of the host’s own inflammatory response.

leucocytes

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5
Q

Early signs on bacterial meningitis

A

Problem, early signs of meningitis can resemble the symptoms of influenza (fever, distinct and severe headache, stiff neck, nausea, vomiting, photophobia (light sensitivity) or analtered mental status (confusion).

**Key: rapid diagnosis. **

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6
Q

Premature babies and newborns up to three months old get what kind of bacterial meningitis

A

group B streptococci (inhabit the vagina and are mainly a cause during the first week of life)

Escherichia coli that normally inhabit the digestive tract and carry the K1 antigen

Listeria monocytogenes

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7
Q

Older children commonly get what kind of bacterial meningitis

A

Streptococcus pneumoniae and Neisseria meningitidis

Haemophilus influenzae type B (HiB, in countries that do not vaccinate)

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8
Q

Adults are most susceptible to what kinds of bacterial meningitis

A

Streptococcus pneumoniae and Neisseria meningitidis together cause 80% of bacterial meningitis cases.

Listeria monocytogenes is a risk in the elderly > 50 years.

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9
Q

Group B Streptococcus (agalactiae) (G+)

Has a capsule:

Has a vaccine:

What do you tx it with?

A

Yes

No

Neonatal sepsis–>meningitis Antibiotic therapy (Beta-lactams)

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10
Q

Streptococcus pneumoniae (G+)

Has a capsule:

Has a vaccine:

How do you identify it?

A

Yes

Yes

Responsible for most pneumonia and see Meningitis diplococcus identified in the CSF

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11
Q

Neisseria meningitidis (G-)

Has a capsule:

Has a vaccine:

What’s an issue with the vaccine?

A

Yes

YEs

Conjugate vaccine does not protect against serotype B, a di-sialic acid homopolymer similar to human structure

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12
Q

Most capsules are composed of________

Anti-capsule antibodies prevent ______

A

polysaccharides

host cell phagocytosis

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13
Q

Most common meningits causing pathogen worldwide

A

Gram negative Haemophilus influenzae.

(left) Small coccobacilli forms seen in sputum.
(right) Thin, pleomorphic forms seen in a 1-year-old unvaccinated child in Africa with overwhelming meningitis.

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14
Q

Capsular polysaccharide of Haemophilus influenzae that is the one we worry about

A

Serov B: has ribose and ribotol

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15
Q

Immunity to Hib

  • Good relationship between age & susceptibility
  • Children < 3 month, ______are protective
  • Most invasive disease occurs between________
A

maternal Abs

3 month and 3 years of age

humoral immunodeficiency

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16
Q
  • Children under 3 years of age show a ________ to Hib
  • Children older than 3 years of age develop ________
A

humoral immunodeficiency

bactericidal Ig to Hib (vaccination/non-clinical exposure)

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17
Q

1st generation Hib vaccine

–Purified capsular polysaccharide of Hib was licensed for immunization (PRP) (1985)

  • 90% effective in children ________
  • ineffective in children ______
A

>24 months

<18 months

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18
Q

Problem with 1st gen HIb vaccine

A

*Problem, Polysaccharides are:

1) poor immunogens
2) stimulate T-independent Ab
3) poor immunologic memory

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19
Q

Describe 2nd generation Hib Vaccine

A

PRP protein conjugates

has diptheria toxoid as the protein carrier

with vaccine tehre is limited clincal concern

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20
Q

Polysaccharide conjugate vaccines stimulate a ____ response and memory response

A

T-Cell dependent antibody response and memory response

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21
Q

Explain difference between polycaccharide only and conjugate vaccine for Hib

A

Polysac will result in no production of memory B cells; we get IgM to Hib but no memory cells

In Conjugate we get both IgM and IgG response; get this very robust response

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22
Q

is Gram negative diplococci and is an intracellular, human-specific pathogen responsible for septicemia and meningitis.

A

Neisseria meningitidis (Nm)

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23
Q

What are the 3 virulence factors in Neisseria meningitis

A

Lipooligosaccharide: component of the outer membrane (endotoxin) which stimulated TLR system to produce: fever, septic shock, and hemorrhage due to the destruction of red blood cells

Polysaccharide capsule: prevents host phagocytosis and evasion of host immune response

Fimbriae which mediate attachment of the bacterium to cells of the nasopharynx.

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24
Q

What is the gold standard to diagnose N.Meningitidis

A

• Gold standard is to isolate Nm as Gram negative diplococci from cerebrospinal

fluid (CSF)
• Culture CFS on chocolate agar plate
• Polymerase chain reaction (PCR) may also be sued to identify Nm

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25
Q

Pathology of N.meningitis

  • Fatality risk approaches 15% within 12 hours of infection, so initiate testing as quickly as possible, but :
  • Persons with confirmed Nm infection should be :
A

do not to wait for the results before initiating antibiotic therapy.

hospitalized immediately for treatment with antibiotics

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26
Q

What is done to prevent N.Meningitis

A

• Nm can be transmitted, so contacts of the infected patient over the 7 days before onset should receive antibiotics to prevent secondary infections, especially young children.

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27
Q

• ~1,000 people get meningococcal disease each year in the U.S. Even when treated with antibiotics, 10–15% of these people die.

It is most common in:

A

infants < one year and 16–21 years.
• Children with certain medical conditions, such as lack of a spleen, have increased risk of getting meningococcal disease.
• College students living in dorms are at increased risk (exposure).

28
Q

While N.Men has 13 serogroups the vaccine targets:

A

6 serogroups (A, B, C, Y, W135 and X) are responsible for virtually all cases in humans.

29
Q

is the preferred vaccine for people 55 years of age and younger.

A

Meningococcal conjugate vaccine (MCV4)

30
Q

has been available since the 1970s. It is the only meningococcal vaccine licensed for **people older than 55 (elderly) **

A

Meningococcal polysaccharide vaccine (MPSV4)

31
Q

(1) β-hemolytic streptococci are classified by _______
(2) α-hemolytic and γ-hemolytic streptococci, which are classified by biochemical testing,

_______ are referred to as viridans streptococci, derived from viridis (Latin for “green”), referring to the green pigment formed by the partial hemolysis of blood agar.

A

Lancefield grouping

a-hemolytic=green

32
Q

Classification of the streptococci

• Hemolysis when grown on blood agar plates measure lysis of blood cells

______ (complete lysis)

______ (partial lysis)

_______(no lysis)

A

b clear (complete lysis)

a green (partial lysis)

g none (no lysis)

33
Q

Descibe the lancifield classification that is based on cell wall components

A

Group A = Strep.Pyogennes (b hemolytic)

Group B = Strep.aglatiae (B hemolytic)

S. Pneumoniae = no lancefiled (aplha hemolytic)

34
Q

Elongated gram-positive cocci arranged in pairs (diplococci) and short chains

A

Streptococcus pneumoniae

35
Q

Key virulence factors in s. pneumonaie

A

Ability to colonize oropharynx (surface protein adhesions)

Spread into normally sterile tissues pneumolysin, IgA protease)

Stimulate TLR inflammatory response (teichoic acid, peptidoglycan fragments),

Evade phagocytic killing (polysaccharide capsule)

36
Q

Disease caused by Strep. pneumonaie

A

• Responsible for pneumonia, sinusitis and otitis media, meningitis, and bacteremia

37
Q

Vaccine for Pneumococcus for children under 2 or Children 6 through 18 and older

A

• PCV13 is given to infants as a series of 4 doses, one dose at each of these ages: 2 months, 4 months, 6 months, and 12 through 15 months.

Infants and Children younger than 2 Years of Age

38
Q

Gram positive, beta-hemolytic

Lancefield typing scheme Group B

Common inhabitant of pharynx, vagina neonatal infections, meningitis

A

Group B streptococcus, Streptococcus agalactiae

39
Q

Pneumococcal vaccine for 65 and older

A

Vaccinate with PPSV23 vaccin

40
Q

2 pneumococcal vaccines:

pneumococcal conjugate vaccine _____

pneumococcal polysaccharide vaccine _____

A

(PCV13)

(PPSV23).

41
Q

What happens to neonates that get infected with Group B strep?

A

neonatal infections, meningitis

– mortality in full-term infants = 2-8%, while in pre-term infants may rise to 30% mortality

42
Q

Tx for newborns with group B strep

A

No licensed vaccine

Penicillin is the drug of choice as a therapy

• Selective prophylaxis antibiotics for Group Bstreptococcus

Pre-term infants

Early membrane rupture (Infection and inflammation)

Previous infant with Group B streptococcal disease

43
Q

Rabies: (Latin for “madness”) has been present in human populations throughout recorded times and probably predates evolution of humans.

– A common cause of death in developing world, but rare in US and developed countries (why would that be?) – annual costs in US associated with post-exposure prophylaxis (PEP) for suspected exposures is significant

A

boring info on rabies

44
Q

how does rabies replicate?

A

Replication: is the prototype for (-) sense RNA viruses

45
Q

Rabies: There is one viral serotype, but several ‘strains’ from different animal species and locations can be identified due to genetic variation – these can be distinguished by

A

monoclonal antibodies or sequence information such that is possible to determine if a human was infected by a dog, bat, etc., rabies virus

46
Q

Rabies: The _____elicits neutralizing antibodies, but natural ‘timing’ of antibody production is not protective.

“Fixing” (primitive inactivation) of virus from rabbit brain yielded the ‘vaccine’ of Pasteur. ___________ allows for vaccine production

A

G glycoprotein

Antigenicity of G protein

47
Q

Entry and invasion features of rabies

A

a. entry is usually through a wound or skin abrasion via s bite and introduction infected saliva

– one report of “aerosol” infection in cave explorers

– can be transmitted by infected cornea transplants, and more recently from organ transplants !!

48
Q

i) “furious” or fulminant – classic rabies presents with:

A

with bizarre behavior; hallucinations; seizures; ‘hydrophobia’, which is violent spasms of respiratory muscles triggered by drinking water: sight, sound, or mention of water can trigger it.

**– ‘fury’ gives way to paralysis, then either coma or sudden fatal cardiac or respiratory arres

49
Q

How do we tx people exposed to rabies?

A

Post-exposure Prophylaxis (PEP, ~20,000/yr in US).

Almost always effective if incubation period is long enough, which is almost always the case. Thus, although an exposure is not a medical dFA emergency, **PEP should be initiated as soon as possible after exposure **

50
Q

Passive vs active immunization for rabies

A

ii. passive immunization – human or equine rabies immune globulin (HRIG/ERIG) introduced into wound area and intramuscularly to provide Ab until immunization becomes effective: keeps virus ‘local’
iii. active immunization – human diploid cell vaccine of “killed virus”. 2010 recommendation: 4 doses at 0,3,7, and 14d, post-exposure (used to be 5 doses, but shortage of vaccine in 2009 necessitated 4 dose, which proved effective

51
Q

Rabies is almost always fatal once _____

A

symptoms appear

*in 2004, the FIRST case of survival where NO immunotherapy intervention was initiated …. this success story happened at our Children’s Hospital of Wisconsin, with Dr. Rodney Willoughby as the lead physician.

52
Q

Describe Dr. Willoughbys rabies tx results

A

reatment based on observations that at death:
i) patient’s brains are ‘normal’, no gross pathology to explain devastating consequences of disease…

ii) there are antibodies during the final acute phase, as if the body mounted an immune response, but just too late…
iii) and, there is often little virus remaining, especially in those who have a prolonged acute phase, showing that the immune response can eradicate the virus…

53
Q

Dr. Willoughby suspected that rabies is a _________ Treatment was based on premise that if one could protect the brain long enough (through therapeutic coma)

for immune system to eradiate virus, the brain would be spared. It worked !!! And has worked 4 additional times (with many failures), most recently in 2011 in an 8-yr-old CA girl.

A

metabolic disease (a disease of ‘software’, not ‘hardware’).

54
Q

LP results:

CSF: WBC = 50-100

Predominant celsl = mononulcear

glucos = normal

protein = <200

A

Viral meningitis

55
Q

LP results:

CSF WBC: 200-500

predominant cells = neutrophils

gluocse = low

protein = 100-500

A

Bacterila meningitis

56
Q

LP results

CSF WBC = 50-300

Predominant cells = mononulcear

Glucose = low

protein = 50-300

A

TB meningitis

57
Q

LP results

CSF WBC = 0-500

Predom cells = mononuclear

glucose = low

>50 protein

A

Crypto meningitis

58
Q

Most common organisms for all meningitis

A

Streptococcus pneumo

59
Q

Alcholics are at risk for what type of meningitis?

A

Listeria(also seenin babies or immuncompromise)

60
Q

PT that has recent brain surgery is most at risk for what causitive organism causing meningitis?

A

staph

61
Q

What tx do you provide to pt with TB meningitis

A

PO rifamipin, isoniazid, pyrasinamide, ethambutol and coritocosteroids

62
Q

What meds would you start on pt you suspect has bacterial meningitis?

A

Empiric therapy:

IV ceftriaxone, vancomycin, corticosteroids

63
Q

What can be done to prevent bacterial meningitis?

A

vaccine for pneumo, menigococcs and H.flu

64
Q

What would we do for old pt with meningitis from listeria?

A

Add ampicillin; as well as the IV ceftrixone, vancomycin, corticosteriods

65
Q

Have 62 yo female acting crazy for few months; has auditory hallucinations and bizzare behavior for past few days. Afebrile, no stiff neck. She is arousable, but disorientd and uncooperative. No focal neuro deficiets, no PMHx, no meds

What is most important microbiologicl etiology to consider?

A

HSV1: because it’s curable!!!!

get imaging and LP

66
Q

See temporal lobe enhancement on CT

CSF shows 97 WBC

88% lymps

glucose 66 and protein 79

A

points to Herpes

start on acyclovir

Neuropysch (18 decks)

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