Microbiology 1: CNS Infections And Meningitis Flashcards
What is the most frequent route of entry for pathogens causing CNS infections ?
Haematogenous spread
List 4 routes of entry to the CNS for pathogens
Haematogenous spread (meningococcus, pneumococcus) Direct implantation (after surgery) Local extension (from the ear) PNS into CNS (rabies)
Which organism is a common cause of neonatal meningitis ?
Group B streptococcus
Floral bacteria in the mothers vagina
What organism commonly causes chronic meningitis ?
Tuberculosis
What organisms can cause aseptic meningitis ?
Enterovirus - coxsackievirus
Herpes simplex
Which organisms cause acute meningitis ?
N.meningitidis
Streptococcus.pneumonia
Haemophilus.influenza
Which N.meningitidis serotypes are there vaccinations for ?
B and C
Which virus transferred by vectors including birds and mosquitoes is becoming a leading cause of encephalitis world wide ?
West Nile virus
Name a bacterial cause of encephalitis ?
Listeria
Which organisms can cause encephalitis via local invasion ?
Amoebae
Which organism causes encephalitis via oral route ? (Eating cat poo 🤮)
Toxoplasmosis- e.g toxoplasma gonadii
What are the most common organisms responsible for brain abscesses ?
Streptococci
Staphylococci
What is the most common route of entry for organisms causing brain abscess ?
Local extension e.g from mastoiditis
Name a common spinal infection ?
Pyogenic vertebral osteomyelitis
What type of meningitis is suggested by this CSF sample ? What are the likely causative organisms ?
CSF appearance: clear Cells: 0-5 leukocytes Gram stain/antigen tests: negative results Protein: 0.15-0.4 g/l Glucose: 2.2-3.3mmol/m
Normal
No organisms
What type of meningitis is suggested by this CSF sample ? What are the likely causative organisms ?
CSF appearance: Turbid Cells: 100-2000 polymorphs Gram stain/antigen tests: positive results Protein: 0.5-3.0 g/l Glucose: 0-2.2 mmol/l
Purulent meningitis (bacterial)
Meningococcus
Pneumococcus
Listeria
What type of meningitis is suggested by this CSF sample ? What are the likely causative organisms ?
CSF appearance: clear/slightly turbid Cells: 15-500 lymphocytes Gram stain/antigen tests: negative results Protein: 0.5-1 g/l Glucose: 2.2-3.3 (normal)
Aseptic meningitis
Coxsackie virus
Echovirus
TB
Could also be:
bacterial meningitis partially treated with ABx
Encephalitis
Brain abscess
What type of meningitis is suggested by this CSF sample ? What are the likely causative organisms ?
CSF appearance: clear/slightly turbid
Cells: 30-500 lymphocytes/ some polymorphs
Gram stain/antigen tests: negative results (scanty acid fast bacilli)
Protein: 1.0-6.0 g/l (high)
Glucose: 0-2.2 (normal)
Tuberculous meningitis
Mycobacterium TB
Culture and microscopy shows a gram +ve, alpha haemolytic diplococcus organism, what is the likely organism causing the meningitis ?
Streptococcus. Pneumoniae
Culture and microscopy shows a gram -ve diplococci which is non-haemolytic, what organism is the likely cause of this meningitis ?
Meningococcus (Neisseria meningitides)
Culture and microscopy shows gram +ve rods, what organism is the likely cause of this meningitis ?
Listeria monocytogenes
Culture and microscopy shows a positive Ziehl-Nielsen stain what organism is the likely cause of this meningitis ?
TB
India ink stain: shows orbit structures (yeast cells with surrounding halos)
Lumber puncture: high opening pressure
What is the likely causative organism of this meningitis ?
Cryptococcus Neoformans
Which organism commonly causes meningitis in men who have sex with men (MSM)
Cryptococcus Neoformans
Which drug is effective against Meningococcus, pneumococcus, haemophilus and e.coli ?
Ceftriaxone I.V
Which drug is effective at treating Listeria ?
Ampicillin
Which organism is most commonly associated with recurrent aseptic meningitis (Mollaret’s meningitis) ?
HSV-1 and HSV-2
Which organisms are the most common cause of aseptic meningitis ?
Enterovirus (80%) - Echovirus, coxsackie virus
