29 Microbiology: Bacterial CNS Infections

Question 1

CSF analysis

• These are vials of CSF
  
  • Which one is healthy?
  • Which one is most likely an infection?
  • What is the reason for the brown hue in the left vial?

Answer 1

Question 2

Pneumococcal Meningitis

• This is an acute purulent type of meningitis. What commonly occurs before patients present with meningitis?
• How does this type of meningitis relate to recurrent/chronic meningitis?

Answer 2

Question 3

Meningococcal Meningitis: Characteristics

• What is the present on the skin of infected patients?
• Does the skin blanch?
• When do these lesions erupt?
• What can occur if they erupt?

Answer 3

Question 4

GBS (S. agalactiae)

• Are they gram (+) or gram (-) ?
• How would you describe what these bacteria look like?
• When does the baby usually get affected?
  
  • How often does colonization cause infection in neonates?
• GBS (+) adults usually have what kind of conditions?

Answer 4

Question 5

Causative Agents: Streptococcus pneumoniae

• What time year are these types of infections more common?
• What 2 populations have a greater risk of infection and subsequent development of meningitis?
• What is important to know about how the microbiome relates to asymptomatic carriers of this pathogen?

Answer 5

Question 6

Adult Signs and Symptoms

• What is considered the classic triad of bacterial meningitis in adults?
• Besides the triad, what other signs and symptoms can patients have?

Answer 6

Question 7

Treatment and Prevention: Meningococcal Meningitis

• What is the drug of choice?
  
  • What can you use if the above answer is contraindicated?
• What should be done with close contacts?
• What kind of vaccine is used for all the infective strains, aside from B, in children, adolescents, or high-risk people?

Answer 7

Question 8

Meningococcal Meningitis: Epidemiology

• What animals carry this bacteria?
• What part of the body is usually colonized first?
• How does infection occur?

Answer 8

Question 9

Meningococcal Meningitis: Patient Groups

• Infants
  
  • Why might this group be difficult to Dx with early-stage infections?
  • What symptoms/signs does later stages of infection have?
• Older children and adults
  
  • What conditions might this population have?

Answer 9

Question 10

Hib Meningitis: Treatment and Prevention

• What can be detected in the CSF in more than 90% of cases?
  
  • How can this give you prognostic information?
• How many Hib conjugate vaccines exist?

Answer 10

Question 11

Seasonality

• All of these organisms are associated with meningitis that occurs in the winter?
  
  1. Which one is associated with late winter and early spring infections that occur in infants?
  2. Which one is associated with both winter and summer infections that affect newborns? When does this same organism have a high incidence of affected predisposed adults? Does it affect healthy adults?
  3. Which organism is associated with infants/toddlers as well as the elderly?
  4. Which one is associated with infants and adolescents?

Answer 11

Question 12

Meningitis

• What occurred between 1986 and 1995 that saw a major shift in the common bacterial causes of meningitis?
• What did this do the incidence of Group B Strep and Strep. pneumoniae?

Answer 12

Question 13

Diagnosis: S. pneumonia

• How do you presumptively ID this bacteria?
• How do you confirm your ID?
  
  • What happens to the bacterial cells with this test?
  • What kind of hemolysis does S. pneumoniae have?
• How do you observe the capsules associated with this bacteria?

Answer 13

Question 14

Dx of Bacterial Meningitis

• What must be done in order to dx this?
  
  • What 3 other basic types of tests can you do to compliment the above procedure or if the above procedure cannot be done?

Answer 14

Question 15

Early vs Late Onset GSB Neonatal Infections

• Occurrence
  
  • Which one is more common
• Time
  
  • When does early onset occur
  • When does late onset occur?
• Pneumonia
  
  • Does this occur in early or late onset?
• Bone/Joint Infections
  
  • Does this occur in early or late onset?

Answer 15

Question 16

Prevention and Prognosis of Neonatal Meningitis

• Prenatal screening can be done to see if pregnant women are infected.
  
  • What organism are mothers screened for?
  • When during pregnancy should they be screened?
• What kind of mortality rate does this condition have?
  
  • What is life like for survivors?

Answer 16

Question 17

Hib Meningitis pathogenesis

• Where are two types of infections common right before getting meningitis?

Answer 17

Question 18

Meningococcal Meningitis:: Epidemiology

• What are the 4 determinants for infection susceptibility in humans?

Answer 18

Question 19

Clinical Manifestations of Listeria monocytogenes

• What are the 2 most dangerous manifestations?
• Neonatal Infections
  
  • What are the devastating results of these type of infections?
• Adult Infections
  
  • What 2 types of unrelated conditions does Listeria monocytogenes commonly cause meningitis in?
  • Encephalitis is a classic feature of this.
    
    • Where in the brain does it occur: brainstem, diencephalon, or telencephalon?

Answer 19

Question 20

Pathogenesis of Listeria monocytogenes

• People who ingest contaminated foods may become infected with Listeria monocytogenes
  
  • What type of cell must first be penetrated? (known as invasion factor)
  • In healthy hosts
    
    • What occurs?
  • In compromised hosts?
    
    • Where does this organism replicate?
    • What occurs first before meningitis can occur?

Answer 20

Question 21

Tx of Bacterial Meningitis

• What must be done right away in order to have the best possible outcomes?
• What drug is used for pneumococcal meningitis?

Answer 21

Question 22

Pneumococcal Meningitis

• What are the 4 main predisposing conditions for this?

Answer 22

Question 23

Pneumococcus

• Capsule
  
  • What cellular process does this inhibit?
  • How does it evade opsonization?
  • Why is this a focus for medical scientists?
• Autolysin
  
  • What does this process release from the bacteria?
  • Why does it do it?
• Pneumolysin
  
  • What does this form in host cells?
  • What does it activate?
• Besides the above, what are the other 3 main virulence factors of this organism?

Answer 23

Question 24

Meningitis: Haemophilus influenza pathogenesis

• What kind of capsule do they have, and how what form of immunity does this help them avoid?
• What are the 2 molecules that virulent strains produce?
• These bacteria infect the nasopharynx. What structure is required for this?
• What is LOS?

Answer 24

Question 25

Meningitis and Neonates * What are the 8 common signs/symptoms of bacterial meningitis in this age group? * E. coli related meningitis is rare in this age group. What are the 2 common pathogens that cause neonatal meningitis?

Answer 25

Question 26

Prions * What are they? * What are some diseases they cause in humans? * What do they cause in deer and why is this concerning?

Answer 26

Question 27

Meningitis Besides vaccines, what else has caused a major decrease in the incidence of meningitis?

Answer 27

Question 28

Seasonality * What are the 3 main community-acquired bacterial causes of Meningitis? * What are the 3 main hospital-acquired bacterial causes of Meningitis?

Answer 28

Question 29

Meningitis: Epidemiology * About 70% of cases of meningitis occurs in what 2 age groups? * In adults * What is the fatality rate? * What percent of patients end up with permanent brain damage? * In children * What are the most common long term effects of meningitis? * US and Global * What is the incidence of meningitis US and worldwide, and what is the fatality rate world-wide?

Answer 29

Question 30

Listeria monocytogenes * This organism posses an LPS-like surface component. What about it' cell wall structure would indicate that it does not have true LPS? * Listeriolysin O (LLO) * What 3 abilities does this virulence factor have?

Answer 30

Question 31

Causative Agents: Streptococcus pneumoniae * Is this gram (+) or gram (-)? * What is unique about their shape? * What is important to remember with meningitis and how common these types of infections are? * What kind of hemolysis do they have, and what does this do to the color of their colonies? * These bacteria have optochin sensitivity. What does that mean? * What kind of strains are virulent?

Answer 31

Question 32

Neonatal Causative Agents: E. Coli * Are these gram (+) or gram (-)? * What do they look like? * What kind of strains are associated with meningitis? * Are these common or rare? * If this organism is the cause of meningitis an adult, what probably recently happened to the adult?

Answer 32

Question 33

Prevention of S. pneumoniae infection * Who usually gets the 23-valent capsular polysaccharide vaccine? * Who usually gets the 13-valent capsular polysaccharide vaccine?

Answer 33

Question 34

Pathogenesis of Bacterial Meningitis * What are the steps that lead to the Edema, increased ICP, and altered blood flow associated with bacterial meningitis?

Answer 34

Question 35

Hib Meningitis pathogenesis * Normal Colonization 1. What structure is first colonized? 2. What layer of cells is penetrated? 3. What must bacteria enter in order to reach the CNS? 4. What part of the brain is seeded first with bacteria?

Answer 35

Question 36

Meningococcal Meningitis: Dx * What can of stain should be performed? * What types of agar will be positive for this bacteria if infected blood or CSF is plated on it? * What can be detected in the CSF?

Answer 36

Chocolate agar is used for growing fastidious respiratory bacteria, such as Haemophilus influenza and Neisseria meningitidis

Question 37

Neonatal Meningitis * What are the 2 **Neonatal** **Factors** that contribute to this? * What are the 5 main **Maternal** **Factors** that contribute to this?

Answer 37

Question 38

Meningococcal Meningitis: Neisseria meningitis * Are these bacteria gram negative or gram positive? * What do they look like? * Do they have a capsule? * Which strains are the most important to remember? * Which strain had a new vaccine just recently made?

Answer 38

Question 39

Meningitis: Haemophilus influenza * Are these bacteria gram negative or gram positive? * Are they mobile? * What is special about their capsule, and why does this make it difficult to ID serotypes? * What kind of hemolysis doe they have?

Answer 39

Question 40

Causative Agents: Listeria monocytogenes * Are these bacteria gram (+) or gram (-)? * What shape do they have? * How do they move? * What kind of preparation can you see this type of motility? * What is notable about the temperature that they can grow in? * How does this make them an excellent foodborne pathogen? * They are a facultative intracellular pathogen. What does that mean?

Answer 40

Question 41

Treatment: S. pneumoniae 1. What is the first line treatment? 2. If the strain is resistant to the answer to number 1, what can you use? 3. What medication is used in children, and why? * If the strain is resistant to the answer to number 3, what do you use?

Answer 41

Question 42

Dx of GSB infection * What factor is would a lab test find to confirm a GSB infection? * What does this look like when plated, compared to S. aureus? * What kind of lysis occurs to RBC's when plated with GSB? * What does the test for the above factor require in order to be conduted?

Answer 42