Bacterial Meningitis Quiz
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What is the primary route through which bacteria commonly enter the cerebrospinal fluid (CSF)?

  • Haematogenous spread (correct)
  • Direct inoculation from surgery
  • Through the respiratory tract
  • Via the lymphatic system

    • Which of the following is a complication associated with bacterial meningitis?

  • Gastrointestinal bleeding
  • Thyroid dysfunction
  • Hearing loss (correct)
  • Kidney failure

    • When evaluating a patient with suspected bacterial meningitis, what specimen is essential to collect for proper diagnosis?

  • Urine sample
  • Throat swab
  • Blood culture
  • Cerebrospinal fluid (CSF) (correct)

    • In the clinical case of the 18-year-old male with a petechial rash, which bacterial infection is most likely indicated?

    <p>Bacterial meningitis</p> Signup and view all the answers

    What aspect of bacterial meningitis is important to consider in terms of prevention?

    <p>Vaccination against specific bacteria</p> Signup and view all the answers

    What is a significant risk factor for acquiring Listeria monocytogenes infection during pregnancy?

    <p>Exposure to contaminated food</p> Signup and view all the answers

    Which of the following conditions is NOT considered a risk factor for bacterial meningitis?

    <p>Strenuous physical activity</p> Signup and view all the answers

    Which bacteria is a leading cause of meningitis and typically resides in the normal upper respiratory tract flora?

    <p>Streptococcus pneumoniae</p> Signup and view all the answers

    In which demographic is asymptomatic carriage of Neisseria meningitidis highest?

    <p>Individuals aged 15-20 years</p> Signup and view all the answers

    Which immunocompromising condition increases the risk of bacterial meningitis?

    <p>HIV infection</p> Signup and view all the answers

    Which organism is a common cause of meningitis in neonates?

    <p>Group B streptococcus</p> Signup and view all the answers

    What host factor increases susceptibility to meningitis by increasing the risk of severe infections with encapsulated bacteria?

    <p>Asplenia</p> Signup and view all the answers

    Which bacterium is NOT typically associated with meningitis in immunocompromised patients?

    <p>E.coli</p> Signup and view all the answers

    What is a common causative organism of meningitis in the elderly?

    <p>Listeria monocytogenes</p> Signup and view all the answers

    Which pathogen primarily causes post-traumatic meningitis following head injury?

    <p>Streptococcus pneumoniae</p> Signup and view all the answers

    What type of meningitis is typically a result of viral infections?

    <p>Common, milder illness</p> Signup and view all the answers

    Following entry into the cerebrospinal fluid, which process leads to inflammation of the meninges?

    <p>Bacterial replication</p> Signup and view all the answers

    What is a notable causative organism of meningitis that exhibits geographical and age-related differences in commonality?

    <p>Neisseria meningitidis</p> Signup and view all the answers

    Which organism is most commonly associated with otitis media, mastoiditis, and sinusitis?

    <p>Streptococcus, e.g., Str. milleri</p> Signup and view all the answers

    What is a common symptom of raised intracranial pressure associated with a brain abscess?

    <p>Headache</p> Signup and view all the answers

    Which factor can contribute to the risk of developing a brain abscess?

    <p>Trauma or neurosurgery</p> Signup and view all the answers

    Which pathogen is commonly associated with endocarditis?

    <p>Streptococcus</p> Signup and view all the answers

    In patients with neutropenia, which organism is frequently implicated in infections?

    <p>Candida</p> Signup and view all the answers

    What is the purpose of long-term prophylaxis with oral penicillin in asplenic patients?

    <p>To reduce the risk of infection with encapsulated organisms</p> Signup and view all the answers

    Which of the following treatments is indicated for close contacts of patients with meningococcal meningitis?

    <p>PO rifampicin x 2/7 or PO ciprofloxacin x 1 dose</p> Signup and view all the answers

    In the clinical case presented, what is the likely source of the patient's symptoms?

    <p>Cerebral abscess secondary to dental infection</p> Signup and view all the answers

    Which of the following pathogens is most likely to be involved in a polymicrobial brain/cerebral abscess?

    <p>Streptococci and anaerobes</p> Signup and view all the answers

    What precaution should be taken until effective antimicrobial treatment is administered for suspected bacterial exposure?

    <p>Droplet precautions for 24 hours</p> Signup and view all the answers

    Which type of infection is NOT indicated for prophylaxis in contacts?

    <p>Pneumococcal meningitis</p> Signup and view all the answers

    What is one potential route for the development of a brain abscess?

    <p>Contiguous spread from sinusitis</p> Signup and view all the answers

    What type of organisms are asplenic individuals particularly at risk for?

    <p>Encapsulated organisms</p> Signup and view all the answers

    What is the primary reason for avoiding lumbar puncture in patients with brain abscess?

    <p>Risk of high intracranial pressure leading to coning.</p> Signup and view all the answers

    What diagnostic method is recommended for imaging a brain abscess?

    <p>CT scan with contrast.</p> Signup and view all the answers

    Which combination of antibiotics should be initiated empirically for treating a brain abscess?

    <p>Ceftriaxone and flucloxacillin.</p> Signup and view all the answers

    What procedure is critical for managing a brain abscess?

    <p>Surgical aspiration or drainage.</p> Signup and view all the answers

    Which of the following sources is most likely to cause a brain abscess in an adult?

    <p>Poor dentition or dental abscess.</p> Signup and view all the answers

    What is the expected duration for the treatment of a brain abscess?

    <p>4-6 weeks.</p> Signup and view all the answers

    What additional action should be taken for a patient diagnosed with meningococcal septicaemia?

    <p>Inform public health authorities.</p> Signup and view all the answers

    What laboratory tests are essential for diagnosing a brain abscess?

    <p>Pus for microbiology and histology, and blood cultures.</p> Signup and view all the answers

    Which of the following factors is least likely to increase the risk of acquiring Listeria monocytogenes infection during pregnancy?

    <p>Age over 65 years</p> Signup and view all the answers

    Which condition represents a compromised immune system that increases the risk of bacterial meningitis?

    <p>Chronic renal failure</p> Signup and view all the answers

    What is a common misconception regarding the demographic most affected by asymptomatic carriage of Neisseria meningitidis?

    <p>It affects individuals aged 35 and older.</p> Signup and view all the answers

    Which of the following is NOT a recognized risk factor for bacterial meningitis associated with recent infections?

    <p>History of asthma</p> Signup and view all the answers

    What is a significant factor that differentiates age groups in the common causes of bacterial meningitis?

    <p>The types of bacteria present in the community</p> Signup and view all the answers

    What condition is characterized by inflammation of the brain parenchyma?

    <p>Encephalitis</p> Signup and view all the answers

    Which method is least likely to lead to apprehension regarding bacterial spread to the cerebrospinal fluid (CSF)?

    <p>Spread from systemic infections</p> Signup and view all the answers

    In managing a brain abscess, which of the following is essential for ensuring effective treatment?

    <p>Surgical intervention to drain the abscess</p> Signup and view all the answers

    Which factor is most directly associated with the increased risk of developing a brain abscess?

    <p>Presence of chronic sinusitis</p> Signup and view all the answers

    What is a significant epidemiological change regarding bacterial meningitis at a global level?

    <p>Increased antibiotic resistance in common pathogens</p> Signup and view all the answers

    Which of the following is NOT a common causative organism of meningitis across all ages?

    <p>Group B streptococcus</p> Signup and view all the answers

    What is the primary underlying mechanism that leads to inflammation of the meninges after bacterial entry into the subarachnoid space?

    <p>Replication of bacteria</p> Signup and view all the answers

    Which condition significantly increases the risk of invasive infection from Neisseria meningitidis?

    <p>Splenectomy</p> Signup and view all the answers

    Which of the following is a potential complication of a fracture or bony defect of the skull?

    <p>Recurrent infections from encapsulated bacteria</p> Signup and view all the answers

    What factor contributes to increased susceptibility to meningitis related to altered immunity?

    <p>Immunosuppressive therapy</p> Signup and view all the answers

    Which bacterium is known to cause meningitis primarily in immunocompromised patients rather than in the general population?

    <p>Cryptococcus neoformans</p> Signup and view all the answers

    What is the role of the cribriform plate in the context of meningitis development?

    <p>Common route for bacterial dissemination</p> Signup and view all the answers

    Which strain of bacteria predominantly causes meningitis in neonates?

    <p>Group B streptococcus</p> Signup and view all the answers

    Which pathogen is associated with brain abscess in patients with neutropenia?

    <p>Aspergillus</p> Signup and view all the answers

    Which clinical feature is NOT typically associated with elevated intracranial pressure in a brain abscess?

    <p>Increased blood pressure</p> Signup and view all the answers

    What is the most common category of organisms involved in otitis media, mastoiditis, and sinusitis?

    <p>Streptococci</p> Signup and view all the answers

    Which of the following is considered a non-bacterial cause of brain abscess?

    <p>Toxoplasma gondii</p> Signup and view all the answers

    In the context of a brain abscess, which organism is most likely implicated in patients with a history of neurosurgery?

    <p>S. aureus</p> Signup and view all the answers

    Which of the following statements is true regarding prophylaxis for infected contacts?

    <p>Oral penicillin is prescribed for asplenic individuals to reduce infection risk.</p> Signup and view all the answers

    What is the most common microbial aetiology found in cases of brain abscess?

    <p>Streptococcus milleri group</p> Signup and view all the answers

    Which of the following is NOT a recommended practice while treating a patient suspected of having a brain abscess?

    <p>Waiting more than 24 hours before starting antibiotics</p> Signup and view all the answers

    In the context of secondary brain abscesses, what does 'haematogenous spread' primarily involve?

    <p>Bacteria entering the bloodstream and spreading from a remote site</p> Signup and view all the answers

    Which antibiotic regimen is appropriate for treating Hib meningitis?

    <p>PO rifampicin x 4/7</p> Signup and view all the answers

    Which of the following best describes a common source associated with the development of a brain abscess in adults?

    <p>Contamination from a dental abscess</p> Signup and view all the answers

    Which factor contributes to an increased risk of infection with encapsulated organisms in patients who are asplenic?

    <p>Loss of splenic function</p> Signup and view all the answers

    What is the recommended protocol for contacts in cases of suspected meningococcal meningitis?

    <p>Administration of PO rifampicin for 2 days</p> Signup and view all the answers

    What is the primary reason for performing a craniotomy in cases of brain abscess?

    <p>For source control through drainage and specimen collection</p> Signup and view all the answers

    Which combination of antibiotics is recommended for the empirical treatment of a brain abscess?

    <p>Ceftriaxone, flucloxacillin, and metronidazole</p> Signup and view all the answers

    What is a key diagnostic method used to identify a brain abscess?

    <p>Imaging, specifically contrast CT or MRI</p> Signup and view all the answers

    What is the expected duration for antibiotic treatment of a brain abscess?

    <p>Up to 6 weeks, depending on clinical response</p> Signup and view all the answers

    What is the recommended action to take regarding public health in cases of meningococcal septicaemia?

    <p>Inform public health authorities for contact tracing and prophylaxis</p> Signup and view all the answers

    Which of the following specimens is essential to collect when suspecting a brain abscess?

    <p>Blood cultures and pus from the brain</p> Signup and view all the answers

    What underlying condition should be treated to reduce the risk of a brain abscess in patients with poor dental health?

    <p>Chronic sinusitis</p> Signup and view all the answers

    Why should a lumbar puncture be avoided in patients with a suspected brain abscess?

    <p>There is a risk of high intracranial pressure and coning</p> Signup and view all the answers

    Study Notes

    RCSI Presentation: Bacterial Meningitis & Brain Abscess

    • RCSI is the Royal College of Surgeons in Ireland (Coláiste Ríoga na Máinleá in Éirinn)
    • The presentation covers bacterial meningitis and brain abscess
    • Learning outcomes include pathogenesis, causes, clinical presentation, complications, diagnosis, management, prevention, and epidemiology of bacterial meningitis, and clinical & microbiological features of brain abscess.

    Learning Outcomes

    • Discuss the pathogenesis of meningitis
    • Describe the causes, clinical presentation, and complications of bacterial meningitis
    • Discuss the diagnosis and management of bacterial meningitis
    • Discuss the prevention of bacterial meningitis and describe the changing local and international epidemiology
    • Describe the basic clinical and microbiological features of brain abscess and how to manage the infection

    Clinical Case 1

    • 18-year-old male university student, unconscious, with petechial rash
    • Shares a house with 4 other students.
    • Likely diagnosis: meningococcal BSI (septicemia)
    • Required specimens: blood cultures, CSF
    • Treatment: ceftriaxone/cefotaxime + vancomycin + steroids
    • Further actions: Inform Public Health, contact tracing, and prophylaxis.

    Clinical Case 2

    • 45-year-old engineer with low-grade temperature, confusion, and new onset seizure
    • Suspected dental abscess
    • Differential diagnoses: brain abscess, encephalitis, tumour, stroke
    • Specimens needed: pus from brain for microbiology, histology, and blood cultures
    • Likely source: dental abscess
    • Treatment: ceftriaxone/cefotaxime + flucloxacillin + metronidazole

    Where is the Inflammation?

    • Meningitis: inflammation of the meninges (tissues surrounding brain and spinal cord)
    • Encephalitis: inflammation of the brain parenchyma (brain tissue itself)
    • Meningoencephalitis: inflammation of both the meninges and the brain parenchyma.

    How do Bacteria get into CSF?

    • Haematogenous spread (most common): from nasopharynx or infection focus
    • Spread from an adjacent infection focus (sinuses, mastoiditis)
    • Spread through a bony defect or head injury: cribriform plate

    Causative Organisms of Meningitis

    • Bacteria (severe): geographical and age-related differences in causative organisms
    • Viruses (common, milder): see lecture on Viral Pathogens of CNS
    • Fungi (uncommon, immunocompromised): e.g., Cryptococcus neoformans
    • Amoebae (very uncommon)

    Following Entry to the CSF

    • Bacteria replicate in subarachnoid space, causing meningitis

    Typical Pathogens (other than viruses)

    • All ages: Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae type b, Group B streptococcus, E. coli, and other aerobic Gram-negative bacilli; Listeria monocytogenes
    • Neonate: Group B streptococcus, E. coli, and other aerobic Gram-negative bacilli
    • Elderly: Streptococcus pneumoniae, Listeria monocytogenes

    Host Factors Increasing Susceptibility to Meningitis

    • Asplenia (absent spleen)
    • Diabetes mellitus and alcohol abuse
    • Altered cell-mediated immunity (immunosuppressive therapy, HIV)
    • Fracture or bony defect of the skull
    • Inherited defects in late complement components
    • Pregnancy (increased risk if Listeria monocytogenes is acquired)

    Risk Factors for Bacterial Meningitis

    • Unvaccinated (HiB, MenC, MenB, etc)
    • Age (common causes vary by age group/living in communal settings)
    • Compromised immune system / HIV, alcohol abuse, diabetes/immunosuppressant drugs / asplenia
    • Recent infection (especially respiratory or ear)
    • Contact with someone with bacterial meningitis
    • Head trauma
    • CSF otorrhoea or rhinorrhoea
    • Travel history (Hajj pilgrimage, Sub-Saharan Africa)
    • Complement pathway deficiency
    • Base of skull fracture
    • Pregnancy

    Causative Organisms: Recap

    • Neisseria meningitidis: Asymptomatic carriage in nasopharynx (highest 15-20 years), incubation period 1–10 days, person-to-person droplet transmission, serogroups A, B, C, W, X, Y
    • Streptococcus pneumoniae: Normal upper respiratory flora, leading in adults; may reach CNS from bloodstream infection, chronic ear, or sinus infection. Can develop penicillin resistance.
    • H. influenzae type b (Hib): Historically major cause meningitis/epiglottitis, vaccination made impact, still prevalent in poorly-resourced countries, high mortality if untreated
    • Listeria monocytogenes: Zoonotic (acquired by ingestion of contaminated meat, contact with infected animals); affects pregnant women, neonates, and the elderly

    Causative Organisms: Recap (continued)

    • Cryptococcus neoformans: Yeast (encapsulated), soil, bird droppings, inhaled into lungs (no symptoms), meningitis in immunocompromised patients (especially HIV) , days to weeks onset, headache predominant.
    • Leptospira interrogans: Zoonotic (clinical features include leptospirosis, meningitis, consider if renal/hepatic failure)
    • Mycobacterium tuberculosis: Onset insidious, symptom weeks/not days/hours , different to acute bacterial meningitis, difficult to diagnose, CSF culture may be negative

    Clinical Signs in Meningitis (continued)

    • Kernig's sign: pain or limited extension when flexing the leg at the hip
    • Brudzinski's sign: involuntary flexion of the legs when flexing the neck

    Rash associated with meningococcal sepsis

    • Purpuric, non-blanching rash (does not fade under pressure)

    What is Sepsis?

    • Infection → host response → organ dysfunction

    Complications of Bacterial Meningitis

    • CNS: hearing loss, subdural abscess, cranial nerve palsies, intellectual problems, hydrocephalus, raised intracranial pressure
    • Outside the CNS: dissemination (bloodstream infection, septic shock)

    Diagnosing Meningitis

    • Clinical assessment is key / Laboratory testing confirms clinical impression/Lumbar puncture:Obtain CSF for microscopy, Gram stain, culture, and PCR. / Blood cultures for detection / Blood for PCR analysis

    Radiology

    • Bacterial meningitis is a clinical and laboratory diagnosis; imaging is not used for diagnosis, but useful to assess for complications (abscess, ventriculitis)
    • If CT required, blood cultures should be obtained and given empiric antibiotics.
    • Starting antimicrobials before LP will reduce likelihood of isolating the causative microorganism from CSF
    • Contraindications to LP include increased intracranial pressure and coagulopathy.

    Laboratory Diagnosis of Bacterial Meningitis

    • CSF microscopy: WBC count, differential, and gram stain; CSF inoculated onto blood and chocolate agar plates and Blood cultures
    • PCR directly on blood and CSF for determination of microbial subtype.

    CSF Characteristics in Meningitis

    • Bacterial: elevated protein, low glucose, elevated white cells (predominantly neutrophils)
    • Viral: elevated protein, normal glucose, elevated white cells (predominantly lymphocytic), other viruses may produce elevated white cells with other components that can differentiate them from bacterial pathogens
    • TB: elevated protein, low glucose, elevated white cells (predominantly lymphocytic)

    Why Take a Blood Culture?

    • Part of sepsis workup, patients with meningitis often have bloodstream infection/organsims may not grow in CSF but may grow in blood/especially important if no CSF sample / subtype of meningococcus

    Diagnosis of Cryptococcal Meningitis

    • Suspicion (e.g., HIV patient with low CD4 count)
    • Lumbar puncture/CSF: cryptococcal antigen detection, microscopy (India ink), fungal culture
    • Blood: cryptococcal antigen detection, blood cultures

    Pre-Hospital Admission

    • Meningitis is a medical emergency (immediate referral)
    • Red flag symptoms (confusion, photophobia, rash, neck stiffness, pain)
    • GPs & advanced paramedics carry benzylpenicillin or ceftriaxone/cefotaxime and administer without delay in patients with fever + petechial/purpuric rash.

    In Hospital: The Basics

    • IV antimicrobials, preferably not oral (crucial in first dose). Do not delay IV antimicrobials while waiting for CT. IV steroids. /IV fluid resuscitation /ICU care (if needed)/Increased ICP requiring fluid restriction /Correction of coagulation abnormalities /Airway protection, intubation, ventilation /Organ failure treatment/Seizure precautions/Public health notification

    Brain Abscess: Pathogenesis & Likely Pathogens

    • Secondary: contiguous spread (from ears, teeth, sinuses), haematogenous spread (via bloodstream infection): possible causative agents include otitis media or mastoiditis / sinusitis (streptococci, staphylococcus, aerobes, anaerobes)/ Trauma - direct inoculation (penetrating head wound, fractured skull, postoperative neurosurgery)
    • Microbial aetiology examples for Likely Pathogens include streptococci, aerobes, and anaerobes (dental/sinus infectious agents). Others include S.aureus, aerobic GNB, aspergillus, Candida.

    Brain Abscess: Clinical Features

    • Signs of raised intracranial pressure (headache, seizures, nausea/vomiting, altered mental status)
    • Signs of infection (high temperature)
    • Signs/symptoms of underlying condition (e.g., ear, dental or sinus infection)

    Brain Abscess: Investigations & Management

    • Investigations: CSF is unlikely helpful in brain abscess, usually avoid LP due to risk of high ICP leading to 'coning'; craniotomy and drainage; Intraoperative specimens to microbiology and histology (gram stain, culture, suscept. analysis)/ blood cultures; imaging (CT/MRI with contrast)
    • Treatment: empirical/local antimicrobial guidelines, CSF culture+susceptibility testing; cefatroxine/3rd gen cephalosporins + flucloxacillin + metronizadole; surgical aspiration/drainage; prolonged treatment (up to 6 weeks); treat underlying conditions (e.g., sinusitis, poor dentition).
    • Non-bacterial causes: Toxoplasma gondii (poorly controlled HIV infection), Aspergillus spp. (single organ/disseminated in immunosuppression)

    Prevention: Vaccination

    • Bacterial meningitis prevention is highly dependent on vaccination:
    • Vaccines are available for meningococcal disease, Hib, and pneumococcal bacteria.
    • At-risk groups, population-level vaccinations

    Prevention: Prophylaxis

    • Asplenia (surgical, congenital, functional): long-term oral penicillin to reduce risk of infection from encapsulated organisms, close contacts of cases to be evaluated, monitored by public health department
    • Meningococcal meningitis & other invasive forms: PO rifampicin x2/7 or PO ciprofloxacin x 1 dose
    • Hib meningitis & other invasive forms: PO rifampicin 4/7 or IV ceftriaxone OD 2/7

    Prevention: Exposure

    • Droplet precautions until on effective antimicrobial treatment (at least 24 hours)

    Antimicrobial Therapy Focus & Duration

    • Blood/CSF cultures to determine causative microorganism/antimicrobial susceptibility testing determines antimicrobial choice/Duration often ranges between 7–21 days (depends on microorganism)
    • Empiric IV antimicrobials depend on age and comorbid conditions.

    Summary of Bacterial Meningitis

    • Bacterial meningitis is a medical emergency and rapid diagnosis is critical
    • Empiric antimicrobials and steroids, resuscitation, and ICU care
    • Clinical assessment, CSF for microscopy, biochemistry, cell count, culture and PCR
    • Blood cultures, and blood for PCR
    • Vaccination significantly reduces cases
    • Brain abscess may mimic tumor and stroke
    • Polymicrobial infections are common

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