Bacterial Meningitis & Brain Abscess 2024 (RCSI PDF)

Leading the world to better health Bacterial Meningitis & Brain Abscess Professor Karen Burns, Consultant Clinical Microbiologist, Beaumont Hospital & Dept. of Clinical Microbiology, RCSI  RCSI Royal College of Surgeons in Ireland Coláiste Ríoga na Máinleá in Éirinn Bacter...

Leading the world to better health Bacterial Meningitis & Brain Abscess Professor Karen Burns, Consultant Clinical Microbiologist, Beaumont Hospital & Dept. of Clinical Microbiology, RCSI  RCSI Royal College of Surgeons in Ireland Coláiste Ríoga na Máinleá in Éirinn Bacterial Meningitis & Brain Abscess Class: Year 2 Semester 1 Course: Undergraduate Medicine Lecturer: Professor Karen Burns Date: 13th November 2024 LEARNING OUTCOMES AT THE END OF THIS SESSION YOU SHOULD BE ABLE TO.......... 1. Discuss the pathogenesis of meningitis 2. Describe the causes, clinical presentation & complications of bacterial meningitis 3. Discuss the diagnosis & management of bacterial meningitis 4. Discuss the prevention of bacterial meningitis & describe the changing local & international epidemiology 5. Describe the basic clinical & microbiological features of brain abscess & how to manage the infection  CLINICAL CASE 1 18 year-old male. University engineering student is found unconscious with a petechial rash He shares a house with 4 other students 1. What is the likely diagnosis? 2. What specimens would you take? 3. What treatment does he need? 4. What else is necessary? WHERE IS THE INFLAMMATION? Meningitis Encephalitis Inflammation of the Inflammation of the meninges brain parenchyma  HOW DO BACTERIA GET INTO THE CSF? 1. Haematogenous spread (the most common) – From the nasopharynx, or from a focus of infection 2. Spread from an adjacent focus of infection – Sinusitis – Mastoiditis 3. Spread from the nasopharynx via a bony defect or with head injury – It is postulated that occasionally entry may occur via the cribriform plate – Head injury – post-traumatic meningitis is rare & typically associated with fracture & persistent CSF leak Source: http://site.motifolio.com/images/Pathogenic-steps-leading-to-meningitis-1021168.png  CAUSATIVE ORGANISMS OF MENINGITIS Bacteria (severe illness) – Geographical & age-related differences in the common causative organisms Viruses (common, milder illness) – See lecture on Viral Pathogens of the CNS Fungi (uncommon, immunocompromised pts) – e.g., Cryptococcus neoformans Amoebae (very uncommon) FOLLOWING ENTRY TO THE CSF Bacteria replicate in the subarachnoid space, causing inflammation of the meninges (MENINGITIS)  THE TYPICAL PATHOGENS (OTHER THAN VIRUSES) Group Organism All ages Streptococcus pneumoniae (pneumococcus) Neisseria meningitidis (meningococcus) Don’t forget M. Haemophilus influenzae type b (Hib) tuberculosis Neonate Group B streptococcus (GBS) E. coli & other aerobic Gram negative bacilli Listeria monocytogenes Elderly Streptococcus pneumoniae Listeria monocytogenes  HOST FACTORS THAT INCREASE SUSCEPTIBILITY TO MENINGITIS 1. Asplenia (absent spleen): Splenectomy, congenital asplenia, functional asplenia – Increased risk of severe infection with encapsulated bacteria: Hib, S. pneumoniae, N. meningitidis 2. Diabetes mellitus and alcohol abuse - S. pneumoniae 3. Altered cell-mediated immunity (immunosuppressive therapy, HIV infection) – Listeria monocytogenes, Cryptococcus neoformans 4. Fracture or bony defect of the skull – Recurrent S. pneumoniae 5. Inherited defects in the late complement components – Recurrent invasive N. meningitidis infection 6. Pregnancy – Increased risk of invasive disease, including meningitis if Listeria monocytogenes is acquired  RISK FACTORS FOR BACTERIAL MENINGITIS Unvaccinated – Complement pathway – HiB deficiency – MenC, MenB, MenACWY – Base of skull fracture – PCV13, PPV23 Pregnancy Age – increases the risk of Listeria – Any age! monocytogenes infection if – but certain common causes exposed via foodstuff vary by age group Recent history of Living in a communal setting – Infection (especially respiratory – college dormitories, asylum or ear) seeker accommodation, military – Contact with someone with bases etc. bacterial meningitis – Head trauma Compromised immune system – CSF otorrhoea or rhinorrhoea – HIV, alcohol abuse, diabetes – Travel mellitus, use of Eg Hajj pilgrimage, meningitis belt in immunosuppressant drugs Sub-Saharan Africa – Asplenia – surgical, congenital or functional  CAUSATIVE ORGANISMS: RECAP Neisseria meningitidis Streptococcus pneumoniae Asymptomatic carriage in Normal upper respiratory tract flora nasopharynx Leading cause of meningitis in – highest in 15-20 yrs; 65 years ii. Asplenia, immunosuppression iii. Chronic renal failure iv. CSF leak, intracranial shunt, cochlear implant IMPACT OF PNEUMOCOCCAL VACCINE Source: Irish Pneumococcal Reference Laboratory IMPACT OF PNEUMOCOCCAL VACCINE PAEDIATRIC INVASIVE INFECTION Data source: HPSC and Irish Pneumococcal Reference Laboratory  PREVENTION: PROPHYLAXIS Asplenia – surgical, Close contacts of a case – in congenial, functional consultation with public Risk of infection with health department encapsulated organisms Meningococcal meningitis – Long-term prophylaxis daily – & /or other invasive oral penicillin meningococcal disease – Reduces risk of infection – PO rifampicin x 2/7 or PO ciprofloxacin x 1 dose Hib meningitis – & /or other invasive Hib disease – PO rifampicin x 4/7or IV ceftriaxone OD x 2/7 Prophylaxis is NOT indicated for contacts of pneumococcal meningitis (&/or other invasive pneumococcal disease) PREVENTION: PREVENTION OF EXPOSURE ≥1m Droplet precautions until on effective antimicrobial treatment x 24 hours (in addition to standard precautions)  CLINICAL CASE 2 45 year-old engineer has a low-grade temperature, is confused & has a new onset seizure He was due to see his dentist for a suspected dental abscess 1. What is the differential? 2. What specimens would you take? 3. What is the likely source? 4. What treatment does he need?  BRAIN/CEREBRAL ABSCESS: PATHOGENESIS 1. Secondary to a focus Microbial aetiology: elsewhere May be polymicrobial (e.g., a) Contiguous – direct spread streptococci & anaerobes) from ears, teeth, sinuses – Nasopharyngeal/oral flora b) Haematogenous – via – Streptococci (35%) e.g., S. bloodstream infection milleri group – Staphylococci (20%) 2. Trauma – direct inoculation – Aerobic GNB (23%) e.g., E. coli of pathogenic microorganisms – Anaerobes (14%) e.g., a) Penetrating head wound Bacteroides spp. b) Fractured skull Clin Microbiol Infect 2003;9:803-809 c) Post-operative (neurosurgery)  LIKELY PATHOGENS Condition Organisms Otitis media / mastoiditis / Streptococci e.g. Str. milleri sinusitis Staphylococcus e.g. S. aureus (most common category) Anaerobes, e.g. Bacteroides Aerobic GNB e.g. E. coli Trauma or neurosurgery S. aureus Neutropenia / Aerobic GNB immunosuppression Aspergillus Candida Mycobacterium tuberculosis HIV Toxoplasma gondii M. tuberculosis Endocarditis S. aureus Streptococci NON- BACTERIAL CAUSES Toxoplasma gondii (e.g., poorly-controlled HIV infection) Aspergillus spp. single organ or disseminated in immunosuppression (e.g., severe & prolonged neutropenia) Images: Prof Michael Farrell, Neuropathology Beaumont Hospital BRAIN ABSCESS: CLINICAL FEATURES Signs of raised intracranial pressure – Headache – Seizures – Nausea & vomiting – Altered mental status Signs of infection e.g. high temperature Signs & symptoms of underlying condition (e.g., ear, dental or sinus infection) Challenging to diagnose  WHAT SPECIMENS WILL YOU SEND & WHAT MICROBIOLOGICAL INVESTIGATIONS WILL YOU REQUEST? Infection is in brain parenchyma not CSF, so CSF usually not helpful and LP should be avoided because of risk of high intracranial pressure leading to “coning” Craniotomy and drainage or Burrhole aspiration – intra- operative specimens to microbiology and histology – Gram stain – Culture & susceptibility – 16S PCR if culture negative Blood cultures – think of haematogenous source Diagnose by imaging (contrast CT/MRI) BRAIN ABSCESS: MANAGEMENT & TREATMENT Source control: surgical aspiration/drainage – Send sample to laboratory Empiric antimicrobials – check local antimicrobial guidelines & consult microbiology/ID – Ceftriaxone (3rd generation cephalosporin) + – Flucloxacillin + – Metronidazole Rationalise antimicrobials once culture & susceptibility results available – Lengthy treatment course expected – up to 6 weeks depending on clinical response and interval imaging findings Treat underlying causes (e.g., sinusitis, poor dentition)  CLINICAL CASE 1 18 year-old male. University engineering student is found unconscious with a petechial rash He shares a house with 4 other students 1. What is the likely diagnosis? Meningococcal BSI (septicaemia) 2. What specimens would you take? Blood cultures, CSF 3. What treatment does he need? Ceftriaxone/cefotaxime & vancomycin + steroids 4. What else is necessary? Inform public health, contact tracing & prophylaxis  CLINICAL CASE 2 45 year-old engineer has a low-grade temperature, is confused & has a new onset seizure He was due to see his dentist for a suspected dental abscess 1. What is the differential? Brain abscess, encephalitis, tumour, stroke 2. What specimens would you take? Pus from brain for microbiology and histology & blood cultures 3. What is the likely source? Dental abscess, poor dentition 4. What treatment does he need? Ceftriaxone/cefotaxime + flucloxacillin + metronidazole  1 2 4 5 6 7 8 3 SAMPLE PSA MCQ: Case presentation: A 68 year old female presents to the Emergency Department A. Amoxicillin complaining of a headache, neck stiffness and B. Amoxicillin, photophobia. On examination there is evidence ceftriaxone, of meningism. Her temperature is 38.5C, BP vancomycin 95/55 mmHg, HR 110 bpm. C. Ceftriaxone, vancomycin Question: What is the most appropriate empiric D. Meropenem antimicrobial management of this patient? E. Vancomycin  SUMMARY Bacterial meningitis is a medical emergency & rapid diagnosis is critical Empiric antimicrobials + steroids, with resuscitation and ICU care if needed Clinical assessment, CSF for microscopy, biochemistry, cell count, culture & PCR Blood cultures and blood for PCR Vaccination significantly reduces meningococcal, pneumococcal & HiB meningitis Brain abscess may mimic tumour & stroke – Polymicrobial infection not uncommon & source control (surgical drainage) is essential Thank you