APATH - MENINGITIS Flashcards
State in full which three (3) bacteria are the major causes of bacterial meningitis in young children (3)
Pneumococcus, Neisseria meningitidis, Haemophilus influenza
Explain why these bacteria are important pathogens in the meninges in young children (4)
Capsule requires IgG for resistance. Born with transplacental maternal IgG which at 3 years is lost and the infant has to develop their own. A window period therefore exists of increased susceptibility.
List six different pathological complications that could result from an acute bacterial meningitis (6x½ = 3)
- Obstructive hydrocephalus (communicating or non-communicating)
- Cranial (especially VIII) or spinal neuritis
- Cranial (or spinal) arteritis, leading to infarcts
- Epilepsy, Subdural empyaema, Brain abscess, Intellectual/neurological deficits, Death
Name three possible major complications that may develop in an adolescent patient with acute bacterial meningitis – and the likely consequences of each (6)
- Obstructive hydrocephalus (usually non-communicating because of basal exudate): ICP, brain herniation, death
- Cranial and/or spinal neuritis: With consequent palsies deepening upon exactly which nerves are affected; most commonly seen is resulting deafness, from involvement of VIII (the auditory nerve).
- Cranial arteritis: Which may lead to one or more areas of infarction of the parenchyma supplied by the involved vessel (the neurologic effects again depending upon the anatomy)
- Brain abscess(-es)
- Subdural empyaema
- Cystic arachnoiditis
Describe the difference in eye signs typically seen in a long-standing case of TB meningitis occurring in a 3-year-old versus a 14-month-old infant. Explain the mechanism (4)
Setting sun sign (Papilloedema +-), Dilated pupil (Papilloedema ++)
[As the optic nerve sheath is continuous with the subarachnoid space of the brain (and is regarded as an extension of the central nervous system), increased pressure is transmitted through to the optic nerve. The brain itself is relatively spared from pathological consequences of high pressure. However, the anterior end of the optic nerve stops abruptly at the eye. Hence the pressure is asymmetrical and this causes a pinching and protrusion of the optic nerve at its head. The fibers of the retinal ganglion cells of the optic disc become engorged and bulge anteriorly. Persistent and extensive optic nerve head swelling, or optic disc edema, can lead to loss of these fibers and permanent visual impairment.]
2 y/o male child’s caregiver at the crèche notices he is irritable and feverish. Gives patient some paracetamol syrup. An hour later he is drowsy and not responding to his mom’s voice. Purplish spotty rash on his face and neck. Dr assesses him & immediately suspects meningococcal meningitis. Sends specimens to the lab and gives a stat dose of an antibiotic. The superintendent immediately notifies the crèche and the authorities of the case before the diagnosis was confirmed by lab findings. Within the same week, 6 other patients from the area were admitted to hospital with meningococcal meningitis.
• State which lesion may be found within the adrenals of the child (1)
• Name this syndrome (1)
• Briefly explain, physiologically, how this adrenal lesion causes shock (1)
• Briefly explain the pathogenesis of the purplish spotty rash (2)
• Explain the difference between leptomeningitis and pachymeningitis (2)
• State which lesion may be found within the adrenals of the child (1) Haemorrhage
• Name this syndrome (1) Waterhouse-Friderichsen Syndrome
• Briefly explain, physiologically, how this adrenal lesion causes shock (1) Lack of cortisol leads to shock [stress hormone]
• Briefly explain the pathogenesis of the purplish spotty rash (2) DIC secondary to gram negative infection
• Explain the difference between leptomeningitis and pachymeningitis (2)
Leptomeningitis = inflammation arachnoid/ subarachnoid space. Pachymeningitis = inflammation of dura
3 y/o female with a 4-day history of headache, vomiting and fever. Diagnosed with otitis media two days ago and prescribed an antibiotic. She is conscious, alert and complains of pain over the neck area. O/E she cries in pain when her neck is flexed. A lumbar puncture (LP) was performed - gram stain is negative for bacteria. Culture growth showed a scanty growth of S. pneumoniae. Her headache improved and she appears less ill following the LP.
Give two (2) haematogenous routes whereby an organism causing otitis media could have entered the brain (2)
Septicaemia, Diploic veins
Give two (2) conditions which would make this child at increased risk for S. pneumoniae (1)
Asplenia, Splenectomy, Sickle cell, HIV, Proteinuria
The finding of organisms on the Gram stain would confirm bacterial meningitis. Given that the child is 5 years old, list the three (3) most likely Gram stain results and give the full name of the organism you would expect for each result (4½)
Gram-negative (intracellular) diplococci (½) Neisseria (½) meningitidis (½)
Gram-negative coccobacilli (½) Haemophilus (½) influenzae (½)
Gram-positive diplococci (½) Streptococcus (½) pneumoniae (½)
Explain immunologically why the three organisms above are the most likely. Contrast these with the two (2) organisms usually encountered in the neonatal period (5)
These have a polysaccharide capsule which requires opsonization for the polymorphs to ingest [and thus kill them]. Opsonins are IgG type antibodies. These cross the placenta from the mother, giving immunity in the neonatal period.
E coli and L monocytogenes are neonatal organisms. These require IgM for protection and there is no transplacental passage of this type of Ab. The baby is thus at risk for these organisms in the neonatal period.
Indicate the likely findings in a sample of CSF obtained from a patient with (acute) bacterial meningitis (4x½ = 2)
- CSF pressure raised (if pressure was measured at the time of the lumbar puncture)
- Fluid turbid
- Pleocytosis – mainly neutrophils
- Decreased or absent glucose [Check serum glucose at the time]
- Raised protein concentration
- Organisms found on gram stain and/or culture
Compared with the findings above, outline two main differences that you would expect in a case of tuberculous meningitis (2)
- Lymphocytes would predominate by far in the pleocytosis, which would not be as marked
- Protein concentration likely to be higher
- Glucose likely to be normal or only slightly reduced
- [In longstanding cases, the chloride concentration may be reduced (from prolonged vomiting)]
3 y/o female child’s day-care mother noticed one morning that she was not her active playful self but quite pale and felt feverish. Child also complained of a headache. Gave her some paracetamol syrup and put her down for a nap. A few hours later child’s condition had deteriorated. She was drowsy and weak, felt cold and clammy and had a purple spotty rash on her arms and chest. Dr did a blood culture and lumbar puncture. He suspected meningitis as there had been an outbreak in the area recently.
CSF/serum: CSF Protein: 0.9g/L (N: 0.2-0.4), CSF Glucose: 0.15 mmol/L (N: approx 2/3 of serum value), Serum glucose: 6.5 mmol/L
CSF microscopy: Neutrophils: 3600/mm3, Lymphocytes: 180/mm3, RBCs: 40/mm3, Gram stain: Gram negative diplococci, ZN Stain (-)
Explain why, if this child has meningitis, it is highly UNLIKELY to be with E. coli organisms (1)
3 y/o - has been able to develop IgM Ab’s [½] required to protect against E coli [½]
Explain CSF… Protein result (1) Glucose result (1) Cell result (2)
Protein result (1) Acute Inflammation increased permeability
Glucose result (1) Organisms extracellular utilize glucose
Cell result (2) Cellular phase of Acute Inflam allows AI cells to exit from the vessels polymorphs are present in high numbers
3 y/o female with a 4-day history of headache, vomiting and fever. Diagnosed with otitis media two days ago and prescribed an antibiotic. She is conscious, alert and complains of pain over the neck area. O/E she cries in pain when her neck is flexed. A lumbar puncture (LP) was performed - gram stain is negative for bacteria. Culture growth showed a scanty growth of S. pneumoniae. Her headache improved and she appears less ill following the LP.
State what is the likely level of the protein in the cerebrospinal fluid (CSF): [markedly low/ moderately low /normal/ moderately raised/markedly raised] (½)
Moderately raised
