Week 3 - C (2) - Microbiology Practical Tutorial questions

Question 1

What are the normal CSF values for White cell count, Red cell count, Protein and glucose?

Answer 1

White cell count - 3 Red cell count - usually 0 but less than 5mm 3 Protein - 150-450mg/L Glucose - 60-70% of blood glucose concentration

Question 2

What age group is viral meningitis most common in? When does it usually occur? What is the most common cause?

Answer 2

Most common in children Usually occurs during summer and autumn Usually caused by enteroviruses (eg echovirus (most common) and coxsachie)

Question 3

Clinical presentation of viral meningitis Headache, fever, neck stiffness, photophobia Need to differentiate from bacterial meningitis How is viral differentiated from bacterial?

Answer 3

Differentiated by carrying out a lumbar puncture

Question 4

What is seen on CSF analysis after a lumbar puncture in viral meningitis?

Answer 4

CSF white cell count raised , not as high as in bacterial and predominantly lymphocytes Protein count normal or slightly raised Glucose usually normal Negative bacteria on gram stain CSF is also clear on inspection

Question 5

How is the type of virus causing the viral meningitis diagnosed?

Answer 5

Take a throat swab CSF PCR for enterovirus (or HSV, VZV) Stool culture for enterovirus also Throat swab, stool culture, CSF PCR

Question 6

What is the treatment for viral meningitis?

Answer 6

Before diagnosis of viral, treat as if bacterial Once viral diagnosed, supportive treatment if enterovirus, start on IV aciclovir if HSV or VZV

Question 7

What are the causative organisms of bacterial meningitis in neonates(up until first month)? Children? 10-21 year olds? 21+ year olds? 65+ year olds?

Answer 7

Neonates - listeria monocytogenase, Group B strep and E.coli Children - H.influenza 10-21 year olds - Neisseria meningitis 21+ - Strep pneumoniae > Neisseria meningitis 65+ - Strep pneumoniae > Listeria monocytogenase Pneumococcal meningitis means strep pneumonia cause Meningococcal meningitis means neissieria meningitis

Question 8

How is group B streptococcus treated? How is it acquired?

Answer 8

Children younger than 3 months 1.4.11 Treat Group B streptococcal meningitis with intravenous cefotaxime for at least 14 days or IV ceftriaxone (usually not given until older than 3 months) with IV amoxicillin for coverage against listeria monocytogenase Occurs within the first days in life and is passed on due to vaginal colonisation of group B strep

Question 9

Neonatal meningiits We know in community acquirred bacterial meningitis that amox/ampicillin is given to cover meningitis in neonates and over 60 If diagnosed with Listeria monocytogenes Found in various foods -soft cheeses, paté What is it treated with?

Answer 9

Treat with amoxicillin (and gentamicin?)

Question 10

Brain abscess an arise from either local spread of infection What is the classic triad of brain abscess symptoms?

Answer 10

Fever, headache and focal neurological signs (ie seizures)

Question 11

How is a brain abscess diagnosed and treated?

Answer 11

Diagnosed via a contrast CT Treated with IV ceftriaxone and IV metronidazole

Question 12

What are the three meningeal layers? Where is a lumbar puncture carried out?

Answer 12

Dura mater- thickest outermost portion Arachnoid mater Pia mater - thinnest innermost portion L3/4 vertebral space into the subarachnoid space

Question 13

Why is a lumbar puncture carried out at L3/4? What are normal CSF white and red cell counts? What are normal protein and glucose CSF levels?

Answer 13

Spinal cord ends at the L1/L2 level and sacrum is fused so really only can carry it out L3-L5 therefore L4 level is chosen as it most likely wont damage the cauda equina Normal White cell count - 3 Normal red cell count is less than 5 also (usually 0) Protein - 150-450mg/L , Glucose - 60-70% of blood glucose levels

Question 14

Is bacteria or viral meningitis more likely to have polymorphs or lymphocytes?

Answer 14

Bacteria - polymorphs (neutrophils) Viral - Lymphocytes

Question 15

An 18 year old fresher is admitted as an emergency. He fell asleep on the couch last night and was difficult to rouse this morning. He has a blotchy purple rash. On admission to hospital he is pyrexial and has a positive kernig’s sign and a positive brudzinski sign. Is it safe to perform a lumbar puncture without a CT scan in this patient?

Answer 15

If his GCS is less than 12 or any focal neurological signs/symptoms then carry out CT This patient would likely recieve a lumbar puncture post CT

Question 16

An 18 year old fresher is admitted as an emergency. He fell asleep on the couch last night and was difficult to rouse this morning. He has a blotchy purple rash. On admission to hospital he is pyrexial and has a positive kernig’s sign and a positive brudzinski sign. CSF WCC - 2815/mm3 (95% polymorphs), CSF RCC - 30 red cells, few gram negative diplococci What is the diagnosis?

Answer 16

Meningococcal meningitis (due to Neisseria meningitis)

Question 17

An 18 year old fresher is admitted as an emergency. He fell asleep on the couch last night and was difficult to rouse this morning. He has a blotchy purple rash. On admission to hospital he is pyrexial and has a positive kernig’s sign and a positive brudzinski sign. What would intiiral treatment have been? What is treatment now diagnosis of bacteria has been confirmed?

Answer 17

Inititally give IV ceftriaxone and IV dexamthasone before LP Now confirmed meningococcal meningitis - change to just IV ceftriaxone

Question 18

An 18 year old fresher is admitted as an emergency. He fell asleep on the couch last night and was difficult to rouse this morning. He has a blotchy purple rash. On admission to hospital he is pyrexial and has a positive kernig’s sign and a positive brudzinski sign. What prophylactic treatment will be offered to people he has come into contact with?

Answer 18

Offer oral ciproflaxacin, oral rifampicin or IV ceftriaxone in children under 12

Question 19

19 year old boy gives a one day history of severe headache with vomiting. Has photophobia and neck stiffness. LP perofrmed and CSF protein is raised (600mg/L) and CSF glucose within normal levels. What type of meningitis is this likely to be? What other qustions for the patient? How would diagnosis be confirmed? What is the treatment and prognosis?

Answer 19

Likely to be a viral meningitis due to enterovirus Ask about sexual history and immunocompromised Should recieve symptomatic treatment as it is likely to be self liiting

Question 20

60 year old man is admitted with 3 day history of headache and increasing confusion. His speech is slurred and difficult to take a history from. He has a temperature and CT shows focal oedema in temporal lobes. What is the likely diagnosis?

Answer 20

Likely to be encephalitis

Question 21

What are some key features of encephalitis?

Answer 21

Insidious onset (few days) Confusion Fever Difficulty speaking

Question 22

What is the usual cause of encephalitis? What treatment should the patient recieve?

Answer 22

Usually caused by HSV Start on IV acicylovir

Question 23

A 75 year old woman is admitted from home having been found confused by neighbours. Neighbours are unsure how long she may have been confused. She has no focal neurological signs but seems to have some neck stiffness and is found to have a fever. She is very droesy. What tests would you prioritise in this patient? (three tests)

Answer 23

Blood culture CT scan Lumbar uncture

Question 24

A 75 year old woman is admitted from home having been found confused by neighbours. Neighbours are unsure how long she may have been confused. She has no focal neurological signs but seems to have some neck stiffness and is found to have a fever. She is very droesy. What treatment would you prescribe immediately?

Answer 24

IV ceftriaxone IV dexamethasone IV amoxicillin as she is above 60 and at risk of listeria monocytogenase

Question 25

A 75 year old woman is admitted from home having been found confused by neighbours. Neighbours are unsure how long she may have been confused. She has no focal neurological signs but seems to have some neck stiffness and is found to have a fever. She is very droesy. What three pathogens are liekly hear?

Answer 25

Streptococcus pneumoniae, listeria monocytogenase, herpes simplex virus

Question 26

A 75 year old woman is admitted from home having been found confused by neighbours. Neighbours are unsure how long she may have been confused. She has no focal neurological signs but seems to have some neck stiffness and is found to have a fever. She is very droesy. WBC - 4500/mm3, few gram positive diplococci What is the diagnoss and what is the treatment now?

Answer 26

Streptococcus pneumoniae Give IV ceftriaxone and IV dexamethasone

Question 27

22 year old admitted to hospital having had a new onset generalized tonic clonic seizure. Reported that for the past few days, complaining of headache, feverish and vomited. Three weeks previously GP treated her for sinusitis, but symtoms didnt improve. CT head on admission showed a ring enhacning lesion in frontal lobe of brin. What is likely diagnosis? What is the empircal treatment?

Answer 27

Brain abscess Treat with IV ceftriaxone and IV metronidazole

Question 28

What organisms can cause a brain abscess?

Answer 28

Streptoccocci - particulary streptoccous milleri Coliforms Staph aureus

Question 29

Where can brain abscess infections usually origniate?

Answer 29

Middle ear infections and sinusitis