Infectious Diseases Flashcards
What 3 symptoms make up the classic triad of meningism?
Neck stiffness
Photophobia
Headache
Which layer of the meninges do bacterial infections most commonly affect?
Sub-arachnoid layer
What are the main causative pathogens of meningism in neonates?
Group B strep
E. coli
Listeria monocytogenes
What are the main causative pathogens of meningism in infants?
Neiserria meningitides
Haemophilus influenzae
Strep pneumoniae
What are the main causative pathogens of meningism in children/adolescents?
N. meningitides
Strep pneumoniae
What are the main causative pathogens of meningism in adults?
Strep pneumoniae
N. meningitides
What are the main causative pathogens of meningism in the elderly?
Strep pneumoniae
Listeria monocytogenes
What pathogen, capable of causing meningites, can be transmitted in soft cheeses and should be of particular concern to pregnant women due to possible vertical transmission?
Listeria monocytogenes (gram positive facultative anaerobe)
If a patient presented with symptoms of meningism, what would be your main suspected causative pathogen if they…
a) had a fractured cribriform plate?
b) had recently had neurosurgery or head trauma?
a) Strep pneumoniae
b) Staph aureus and epidermidis
What is Waterhouse-Friederichsen Syndrome?
What pathogen is it associated with?
Form of rapidly escalating fulminant meningococcal disease with accompanying septicaemia, bilateral haemorrhages into the adrenal glands and DIC
Associated with N meningitides
What was previously the most common cause of meningitis in children until the introduction of a vaccine?
What is now the most common cause?
Previously Haemophilus influenzae
Now N meningitides
Other than meningism, there are some other clinical signs of meningeal infection.
What are Kernig’s sign and Brudzinki’s sign?
Kerning sign - patient resists knee extension when their hip is flexed. May be positive in meningococcal disease
Brudzinki’s sign - flexion of the neck will ellicit flexion of the hip and knee joints
So you’ve got a patient with suspected meningitis - what investigations do you perform?
Urgent CT - required to rule out increasing cranial pressure (always indicated prior to LP?)
According to ward notes, LP is the most urgent test to perform but a CT should be performed first if the patient has a reduced GCS
How is community acquired meningitis treated? What additional treatment may be of benefit within the first 12 hours of symptoms?
What would you add if the patient was over 60, or immunocompromised?
Treated with IV Ceftriaxone 2g BD
If first 12 hours, add IV dexamethasone 10mg QDS
If the patient is over 60 or IC/IS, add IV amoxicillin 2g every 4 hours
When treating a patient with meningitis, what additional medication would you add if you suspected encephalitis?
IV Aciclovir
Are there any contact precautions that should be taken by those close to someone with confirmed meningitis?
Yes, treat prophylactically with Ciprofloxacin
What would the following LP results suggest as a cause of meningitis?
Clear fluid
Raised cell count
Low/normal glucose
Normal Protein
Normal opening pressure
Asceptic/Viral meningitis
What type of viruses are commonly associated with asceptic meningitis?
What type of viral meningitis can lead to a more severe infection and potentially encephalitis?
Enteroviruses are most commonly associated with viral meningitis
HSV infection is associated with more severe meningitis and subsequent encephalopathy
How is asceptic meningitis managed?
In many cases the condition is self-limiting and is managed conservatively
If infection is severe, IV Aciclovir may be used
What would the following LP results suggest as a cause of meningitis?
Clear CSF
Culture negative
Raised white cells
Low blood glucose
High protein
Elevated opening pressure
Fibrin webs appear if the CSF is left to settle
Tuberculosis meningitis
What is the diagnosis?
Child presents with rapidly developing signs of severe infection over the course of 24 hours, excessive drooling, difficulty swallowing, voice changes, fever and increased resp rate
What does the presence of stridor indicate?
Epiglottitis/Supraglottitis
Presence of stridor indicates upper airway obstruction and is an indication of emergency
Historically epiglottitis was most commonly caused by Haemophilus influenzae type B, however since vaccination this has become less common.
What are the most common causes now of epiglottitis?
Strep pneumoniae
Strep pyogenes
Staph aureus
Other than bacterial infection, what else might cause epiglottitis/supraglottitis?
Severe burns/trauma
Excessive use of crack cocaine
Graft vs Host Disease
How is epiglottitis medically managed?
IV Ceftriaxone, 2g OD
When diagnosing community acquired pneumonia, assessing the patient with CURB65 is useful.
What does CURB65 refer to?
Confusion (new onset)
Urea (Blood Urea Nitrogen) greater than 7 mmol/l
Respiratory rate of 30 or more
BP less than 90 systolic or 60 diastolic
Age 65 or older
What is the most common causative organism of CAP?
Strep Pneumoniae
What might be the causative pathogens of pneumonia in a patient with IC/IS?
H. influenzae
Pneumocystis jirovecii
What might be the causative pathogens of pneumonia in neonates?
Group B Strep (S. agalacticae)
Listeria monocytogenes
HSV
Adenovirus
Mumps
Enterovirus
Chlamydia trachomatis
Give an example of (and an associated condition)…
Group A Strep
Group B Strep
Group A Strep - Strep. pyogenes (
Suspect CAP? What investigations do you perform?
Clinical examination and CURB65
CXR
+/- Sputum examination
How is mild/moderate CAP treated (CURB65 score of 0-2)?
IV/PO Amoxicillin, 1g TDS for a total of 5 days
If penicillin allergic, give PO Doxycycline on day 1 then 100mg OD or IV Clarithromycin
How is severe CAP treated (CURB65 3 or more, or in the ICU/HDU, or if nil by mouth)
IV Co-amoxiclav 1.2g TDS
AND
IV Clarithromycin 500mg BD for a total of 7 days
If penicillin-allergic, give IV Levofloxacin 500mg BD monotherapy
Step-down therapy for all patients is PO Doxycycline 100mg BD
HAP is, after UTI, the most common nosocomial infection seen and lengthens hospital stay by 1-2 weeks. It can be caused by both bacteria and viruses.
What are the most common causes of both?
Bacteria - most commonly caused by gram-negative rods (Pseudomonas aeruginosa), but can also be caused by Staph aureus, H influenzae, Klebsiella and enterobacter
Viral - influenza, RSV and CMV in immunocompromised hosts
How is non-severe HAP treated?
PO Amoxicillin for total 5 days
If penicillin allergic, PO Doxycycline 100mg BD
How is severe HAP treated?
IV Amoxicillin AND Gentamicin
If penicillin-allergic, IV Co-trimoxazole and Gentamicin
Step-down to PO Co-trimoxazole
All IV/PO therapy should total 7 days
When would you treat an exacerbation of COPD?
What medications are used?
If there is purulent discharge, or signs of consolidation/pneumonia on CXR
Treat with Amoxicillin 500mg TDS, or if penicillin-allergic with Doxycycline 200mg on day 1 then 100mg OD for a total of 5 days
What is Duke’s criteria used for?
It consists of major and minor criteria - what are the two major criteria?
Duke’s criteria is used to assess likelihood of endocarditis
The two major criteria are…
positive blood cultures for infective endocarditis
evidence of endocardial involvement
