CNS Infection: Some Cases

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SOME CASES

CNS infections can present in so many ways. Here are a few cases to get you thinking. Obviously they’re all CNS infections – can you guess the likely bugs?
Following this we’ll go through it all systematically, but this is just to give an overview…

1. A newborn, premature, low-birthweight baby is found to be hypothermic. They are not feeding well, irritable and tachypnoeic.
If this is a CNS infection, name 2 bacteria that are most likely to cause meningitis in this context…

Group B Strep (strep agalactiae)
Escheria coli

65-75 % of cases of sepsis or meningitis within 72 hours of birth caused by GBS or E. coli.

Early-onset infections reflect vertical transmission from maternal genital tract flora.

Increasing peripartum antibiotic prophylaxis may be associated with a shift in the pathogens causing sepsis in preterm and very low-birthweight infants, with Escherichia coli becoming a more prevalent cause.
Heath 2014 | Stoll 2011 | Stoll 2020

2. A 2 year old toddler from a family who are vaccination hesitant presents with fever, vomiting, headache and feeling unwell. They also complain of leg pain. On examination they have pale skin, and cold hands and feet.
Name the 3 bacteria that are most likely to cause this?

Strep pneumoniae
Neisseria meningitidis
Haemophilus influenzae type B

Strep pneumoniae and N. meningitidis are the most common pathogens in this age group, together accounting for 60-70% cases. Less common pathogens in this age group include group A streptococcus and GBS, H. influenzae, and other gram-negative organisms.

Nigrovic 2008

3. A 22 year old uni student presents with headache, photophobia, neck stiffness and a non-blanching rash.
Name the 2 bacteria that are most likely to cause this?

Neisseria meningitidis
Strep pneumoniae

4. An immunocompetent 55 year old female with no travel history presents with fever, headache, confusion, word finding difficulties and a focal seizure.

Which virus is most likely to cause these presentation?

HSV type 1

HSV 1 is common cause of sporadic encephalitis.

It is important to diagnose because it is treatable, and the success of treatment is related to how early therapy is initiated.

5. An 80 year old gentleman presents with fever, drowsiness and headache.

Which bacteria must you think of as a cause of his meningitis that alters his treatment compared to a younger patient?

Listeria monocytogenes

6. A 4 year old boy who’s recently moved from Nepal presents with a several week history of headache, and now photophobia

Which organism should be specifically considered in his differential diagnosis?

TB meningitis

7. A 32 year old landscape gardener who plants eucalyptus trees presents with a 6 week history of confusion, altered mental state, headache, nausea and vomiting.

Any particular organism you should think of here apart from the more common bacterial and viral causes of meningitis?

Cryptococcus (gattii specifically) – this organism is associated with Eucalyptus trees (esp Red River Gum) and can affect immunocompetent individuals
REF

8. A 56 male has an external ventricular drain (EVD) inserted to manage hydrocephalus complicating an intracranial hemorrhage. The EVD is now 14 days old. He develops a fever, with no other obvious source.

Name 2 organisms that are likely to infect an EVD.

Staphylococcal aureus (50%)
Staphylococcal epidermidis (33%)

Shunt infections most frequently develop via colonization of the shunt with skin flora.
Early infection with skin flora is the most common type of shunt infection; about half of all shunt infections are due to coagulase-negative staphylococci and about a third of cases are due to Staphylococcus aureus. Diphtheroids (such as Cutibacterium [formerly Propionibacterium] acnes and Corynebacterium jeikeium) may also be pathogenic.

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CNS Infection: Some Cases

SOME CASES

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