[10.09a] Diffuse Neurological Infections (Part 1) V2.pdf

Membranous coverings of the brain and spinal cord

What are the meninges?

Dura mater

What is the outermost, toughest, and thickest layer of the meninges?

Endosteal and meningeal

What are the two layers of the dura mater?

Meningeal layer

Which layer of the dura mater is specifically inflamed in meningitis?

Arachnoid mater

What is the middle, thin layer of the meninges filled with CSF?

Pia mater

What is the innermost, delicate layer that adheres to the brain surface?

Triangle of Death

What is the area from the bridge of the nose to the corners of the mouth called?

Cavernous sinus

Through what network of veins behind the orbit can facial infections spread to the brain?

Meningitis

What is the term for inflammation of the meninges?

Acute bacterial meningitis

What is an acute purulent infection within the subarachnoid space?

Meningoencephalitis

What is the inflammation of the meninges, brain parenchyma, and subarachnoid space?

Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae

Which three bacteria are referred to as SNH?

Listeria monocytogenes

Which etiologic agent is noted as not being found in the Philippines?

Group B Streptococcus

Which agent is considered rare in the Philippines but is part of newborn screening?

Streptococcus pneumoniae

Which etiologic agent is the most common cause of meningitis in adults?

Group B Streptococcus

What is the predominant cause of meningitis among neonates?

S. agalactiae

What is another name for Group B Streptococcus?

Individuals over 50 years old with comorbidities

Besides neonates, GBS is increasing in frequency in which population?

Fulminant sepsis and ARDS

What are two other diseases Group B Streptococcus may cause?

35th to 37th week

At what week of gestation is a GBS culture requested for pregnant women?

Gram positive cocci

What is the Gram stain and morphology of GBS?

Catalase negative

Is GBS catalase positive or negative?

Beta hemolytic

What is the hemolysis pattern of GBS?

Bacitracin resistant

Is GBS sensitive or resistant to bacitracin?

Children and young adults (2 to 20 years old)

In what age group do 60 percent of Neisseria meningitidis cases occur?

Meningococcemia

What condition caused by N. meningitidis presents with an erythematous rash and petechiae?

Trunk, lower extremities, mucous membranes, and conjunctiva

What four areas are commonly involved in the skin lesions of meningococcemia?

Neisseria meningitidis

What is the only bacterium capable of generating epidemics of meningitis?

Waterhouse Friderichsen Syndrome

What syndrome involves primary acute adrenocortical insufficiency and bilateral adrenal hemorrhage?

Gram negative diplococci

What is the Gram stain and morphology of N. meningitidis?

Kidney shaped

How is the shape of N. meningitidis diplococci described?

Oxidase positive

Is N. meningitidis oxidase positive or negative?

Dark purple

What color does a positive oxidase test turn?

Polysaccharide capsule

What is used to categorize the 13 serogroups of N. meningitidis?

Serogroups A, C, Y, and W 135

Which four N. meningitidis serogroups are used for vaccines?

Pili

What structure does N. meningitidis use for motility?

LPS (Lipopolysaccharide)

What component causes the toxic effects of N. meningitidis?

Complement dependent antibodies

What mediates immunity against N. meningitidis?

Hib vaccine

Why has H. influenzae type B meningitis declined in the Philippines?

Gram negative coccoid bacilli

What is the Gram stain and morphology of H. influenzae?

Satellite phenomenon

What is the term for H. influenzae growing around S. aureus colonies?

NAD (Nicotinamide adenine dinucleotide)

What substance released by S. aureus allows H. influenzae to thrive?

Factor V

Which growth factor is equivalent to NAD or Coenzyme A?

Factor X

Which growth factor is equivalent to Hemin?

Unencapsulated or Nontypeable (NTHi)

Which category of H. influenzae is part of the normal flora and causes mucosal infections?

Nontypeable H. influenzae

What is currently the most common cause of invasive H. influenzae disease in countries with routine Hib vaccination?

PRP (Polyribosyl ribitol phosphate)

What is the specific capsular antigen found in H. influenzae Type B?

Hib

Which is the most virulent strain of H. influenzae?

Pneumonia, sinusitis, and otitis media

What are three common risk factors/preceding conditions for pneumococcal meningitis?

Alcoholism

In what condition is depressed phagocytic activity a risk factor for S. pneumoniae?

20 percent

What is the mortality rate for S. pneumoniae meningitis?

Lancet shaped diplococci

What is the morphology of S. pneumoniae?

Alpha hemolytic

What is the hemolysis pattern of S. pneumoniae?

Optochin sensitive

Is S. pneumoniae sensitive or resistant to optochin?

Quellung reaction

What test results in a halo effect due to capsular swelling?

Type specific capsule

What is the primary virulence determinant of S. pneumoniae?

GI route (contaminated food)

How does Listeria monocytogenes enter the body?

Coleslaw, cheese, hotdogs, and cold cuts

What are four types of food often contaminated with Listeria?

Neonates, pregnant women, elderly, and immunocompromised

What are the four populations primarily at risk for Listeria?

Granulomatosis infantiseptica

What in utero infection causes neonatal sepsis and multiple organ granulomas?

Gram positive bacilli

What is the Gram stain and morphology of L. monocytogenes?

Catalase positive

Is Listeria catalase positive or negative?

4C, low pH, high salt

Under what three harsh conditions can Listeria survive?

Tumbling motility

What specific motility is observed in Listeria at 22 to 28C?

Beta hemolytic

What is the hemolysis pattern of Listeria?

Serotype 4b

Which Listeria serotype is the most pathogenic?

Adhesins

What proteins facilitate Listeria binding to host cells?

Siderophores

What high affinity iron chelating compounds does Listeria use to obtain iron?

Enterobacters

What is another name for enteric gram negative bacilli?

Head trauma and neurosurgical procedures

In what clinical settings are Enteric gram negative bacilli usually seen?

Nasopharynx

Where do most meningitis causing bacteria (except Listeria) enter and attach?

Polysaccharide capsule

What structure allows bacteria to avoid phagocytosis and complement in the bloodstream?

Choroid plexus

Through what structure does meningeal invasion occur?

Few WBCs, low complement, and low immunoglobulins

Why do bacteria multiply rapidly within the CSF?

TNF and IL 1

Which two cytokines are produced by CSF leukocytes during the inflammatory response?

Lipopolysaccharide

What cell wall component is released upon the lysis of Gram negative bacteria?

Teichoic acid and peptidoglycans

What cell wall components are released upon the lysis of S. pneumoniae?

Selectins

The upregulation of which proteins on endothelial cells promotes leukocyte adherence?

CSF outlet obstruction

What occurs due to the leakage of serum proteins into the subarachnoid space?

Cerebral ischemia

What is caused by increased ICP compromising blood flow?

Decreased CSF glucose

What CSF biochemical change results from increased glucose utilization by the brain?

Fever, Headache, Nuchal Rigidity

What is the classic triad of meningitis?

Nuchal rigidity

What symptom is caused by inflammation stimulating nociceptive fibers in the meninges?

Increased ICP

What is the major cause of obtundation and coma in meningitis?

Papilledema, gait instability, and CN VI palsy

What are three symptoms of increased intracranial pressure?

Biopsy of petechiae

What specific specimen can be used for Neisseria diagnosis?

Chocolate agar

What culture medium is used with growth factors for meningitis diagnosis?

Increased

What happens to the opening pressure in bacterial meningitis?

Neutrophils

Which white blood cell type predominates in the CSF of acute bacterial meningitis?

Decreased

What happens to glucose levels in the CSF of bacterial meningitis?

Increased

What happens to protein levels in the CSF of bacterial meningitis?

Neuroimaging (CT or MRI)

What should be performed prior to a lumbar puncture if increased ICP is suspected?

Epidemiology

What is the basis for empiric antibiotic therapy?

Penicillin G or Ampicillin

What is the antibiotic of choice for penicillin sensitive N. meningitidis?

Ceftriaxone or Cefotaxime

What third generation cephalosporins are used for penicillin resistant N. meningitidis?

Vancomycin

What is added to cephalosporins for penicillin resistant S. pneumoniae?

Ampicillin plus Gentamicin

What is the treatment for Listeria monocytogenes?

Nafcillin

What is used for methicillin sensitive Staphylococcus?

Ceftazidime, Cefepime, or Meropenem

What are three antibiotic options for Pseudomonas?

Dexamethasone

Which adjunct steroid therapy is given 20 minutes before antibiotics?