Bacterial Meningitis Overview
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Questions and Answers

What is the most common route through which bacteria enter the cerebrospinal fluid (CSF)?

  • Haematogenous spread (correct)
  • Through a surgical procedure
  • From an adjacent focus of infection
  • Directly from the bloodstream

    • Which symptom is most likely associated with bacterial meningitis, as seen in the clinical case?

  • Stiff neck
  • Severe headache
  • Petechial rash (correct)
  • High fever

    • What is a key component in the management of a patient diagnosed with bacterial meningitis?

  • Antibiotic therapy (correct)
  • Intravenous hydration only
  • Antiviral medications
  • Surgical intervention

    • In discussing the prevention of bacterial meningitis, what should be emphasized?

    <p>Vaccination programs</p> Signup and view all the answers

    What differentiates meningitis from encephalitis based on their definitions?

    <p>Meningitis involves inflammation of the meninges.</p> Signup and view all the answers

    Which risk factor increases the likelihood of contracting Listeria monocytogenes during pregnancy?

    <p>Increased exposure to foodborne pathogens</p> Signup and view all the answers

    What specific population is most likely to asymptomatically carry Neisseria meningitidis?

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

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

    <p>Participating in outdoor sports</p> Signup and view all the answers

    Which underlying condition increases a person's risk for invasive bacterial disease such as meningitis?

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

    What factor is associated with a higher risk of infection for individuals traveling to sub-Saharan Africa?

    <p>Travel during the Hajj pilgrimage</p> Signup and view all the answers

    What is a common causative organism of meningitis in all age groups?

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

    Which patient condition significantly increases the risk of severe infection with encapsulated bacteria?

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

    Which of the following organisms is commonly associated with meningitis in neonates?

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

    What is a rare cause of post-traumatic meningitis?

    <p>Fracture of the skull</p> Signup and view all the answers

    Which organism is considered uncommon and affects immunocompromised patients?

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

    Diabetes mellitus has been linked to an increased risk of meningitis caused by which organism?

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

    What is a typical feature of how bacteria cause meningitis after entering the CSF?

    <p>Replication in subarachnoid space</p> Signup and view all the answers

    Which of the following factors is NOT associated with increased susceptibility to meningitis?

    <p>Regular physical exercise</p> Signup and view all the answers

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

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

    In a patient with neutropenia, which of the following organisms is least likely to be a concern?

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

    Which clinical feature is indicative of a brain abscess?

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

    What non-bacterial pathogen is associated with poorly-controlled HIV infection?

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

    Which of the following is a sign of raised intracranial pressure?

    <p>Severe headaches</p> Signup and view all the answers

    Which group of infections requires long-term prophylaxis with daily oral penicillin?

    <p>Asplenic patients</p> Signup and view all the answers

    Which of the following is a common microbial etiology of brain abscesses from a hematogenous source?

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

    In the case of meningococcal meningitis, which prophylactic treatment is indicated for close contacts?

    <p>Oral ciprofloxacin as a single dose</p> Signup and view all the answers

    What is a key precaution when dealing with a patient suspected of having an infectious droplet spread illness?

    <p>Droplet precautions until effective antimicrobial treatment for at least 24 hours</p> Signup and view all the answers

    Which condition is NOT indicated for prophylaxis in contacts of a patient with pneumococcal meningitis?

    <p>Other invasive pneumococcal disease</p> Signup and view all the answers

    Which of the following is a likely diagnostic step for a patient presenting with confusion and seizures?

    <p>CT or MRI of the brain</p> Signup and view all the answers

    What type of exposure risk is considered for a patient with a dental abscess exhibiting neurologic symptoms?

    <p>Possible direct inoculation from dental procedures</p> Signup and view all the answers

    Which of the following best describes the microbial profile associated with anaerobic infections from a dental source?

    <p>Composed primarily of anaerobes such as Bacteroides spp.</p> Signup and view all the answers

    What is the main reason that lumbar puncture (LP) should be avoided in cases of brain infection?

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

    Which imaging modality is recommended for diagnosing brain infections?

    <p>Contrast CT or MRI</p> Signup and view all the answers

    What is a common empirical antimicrobial regimen for treating brain abscess?

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

    What should be done after obtaining culture and susceptibility results in a patient with a brain abscess?

    <p>Rationalise antimicrobials based on results</p> Signup and view all the answers

    In cases of suspected meningococcal septicaemia, which specimen is NOT typically taken?

    <p>Pus from lesions</p> Signup and view all the answers

    What is an important step in managing public health when a meningococcal infection is identified?

    <p>Administering antibiotics to all housemates</p> Signup and view all the answers

    Identifying the source of a brain abscess is essential. What is the likely source in a patient with poor dental health?

    <p>Dental abscess</p> Signup and view all the answers

    Following a brain surgery to drain an abscess, what type of specimens should be sent to the laboratory?

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

    What is the primary mechanism through which bacteria commonly enter the cerebrospinal fluid (CSF)?

    <p>Haematogenous spread from distant sites</p> Signup and view all the answers

    Which of the following conditions is primarily characterized by inflammation of the brain parenchyma?

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

    In which situation is prophylactic treatment for meningococcal meningitis most critical?

    <p>Following exposure to a confirmed case of meningococcal disease</p> Signup and view all the answers

    How should the management of a brain abscess change after the infection source has been identified?

    <p>Tailor antibiotic therapy based on culture results</p> Signup and view all the answers

    Which specimen is generally NOT collected during the initial workup for suspected meningococcal septicaemia?

    <p>Nasal swab</p> Signup and view all the answers

    Which factor is associated with an increased risk of acquiring Listeria monocytogenes during pregnancy?

    <p>Diet high in processed meats</p> Signup and view all the answers

    Which condition can increase susceptibility to bacterial meningitis due to compromised immune function?

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

    What is a common characteristic of Neisseria meningitidis in relation to certain populations?

    <p>Highest asymptomatic carriage is seen in teens and young adults</p> Signup and view all the answers

    Which factor is unlikely to contribute to the risk of bacterial meningitis in communal living settings?

    <p>High levels of individual vaccinations</p> Signup and view all the answers

    Which of the following is a recognized risk factor for invasive diseases such as meningitis?

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

    Which of the following organisms is least likely to be associated with a brain abscess following trauma or neurosurgery?

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

    Which clinical feature is specifically indicative of an underlying infection that might lead to a brain abscess?

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

    In a neutropenic patient, which of the following pathogens poses the highest risk for developing a brain abscess?

    <p>Aerobic GNB</p> Signup and view all the answers

    What is the most likely cause of a brain abscess in a patient with poorly-controlled HIV infection?

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

    Which of the following statements about the diagnosis of brain abscess is correct?

    <p>Diagnosis often requires imaging and clinical features.</p> Signup and view all the answers

    Which organism is commonly associated with meningitis in the elderly population?

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

    What impact does asplenia have on susceptibility to bacterial meningitis?

    <p>Increases risk of severe infection with encapsulated bacteria</p> Signup and view all the answers

    What is a common causative organism of meningitis in neonates?

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

    What is a significant host factor contributing to the recurrent infection of Neisseria meningitidis?

    <p>Inherited defects in complement components</p> Signup and view all the answers

    Which factor is associated with an increased risk of contracting Listeria monocytogenes infection?

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

    What bacterial infection is most commonly linked to skull fractures and bony defects?

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

    What type of organism is Cryptococcus neoformans considered in relation to meningitis?

    <p>Uncommon, affecting immunocompromised patients</p> Signup and view all the answers

    What is a potential route for bacteria to enter the cerebrospinal fluid during trauma?

    <p>Through the nasal cavity via the cribriform plate</p> Signup and view all the answers

    Which of the following is true regarding the microbial etiology of brain abscesses from hematogenous sources?

    <p>Streptococci form a significant percentage of the microbial profile.</p> Signup and view all the answers

    In which case is long-term prophylaxis with daily oral penicillin indicated?

    <p>In congenital asplenia.</p> Signup and view all the answers

    What is NOT a recognized treatment option for contacts of a meningococcal meningitis case?

    <p>Long-term oral penicillin.</p> Signup and view all the answers

    Which of the following droplets precautions must be taken until effective antimicrobial treatment is initiated?

    <p>Droplet precautions until 24 hours after starting treatment.</p> Signup and view all the answers

    Which scenario may lead to a brain abscess secondary to contiguous infection?

    <p>Untreated dental abscess leading to infection.</p> Signup and view all the answers

    What is the primary source of infection in patients presenting with confusion, low-grade fever, and seizures?

    <p>Contiguous spread from dental or sinus infections.</p> Signup and view all the answers

    Which of the following statements about the pneumococcal vaccine is false?

    <p>It is indicated for all cases of pneumococcal meningitis.</p> Signup and view all the answers

    Which microbial pathogen group has a significant role in the development of brain abscesses due to hematogenous spread?

    <p>Both streptococci and anaerobes can be involved.</p> Signup and view all the answers

    What is the primary reason lumbar puncture (LP) should be avoided in cases of brain infection?

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

    Which medicinal regimen is commonly used for empiric treatment of a brain abscess?

    <p>Ceftriaxone, Flucloxacillin, and Metronidazole.</p> Signup and view all the answers

    When should antimicrobial therapy be rationalised in the management of a brain abscess?

    <p>Once culture and susceptibility results are available.</p> Signup and view all the answers

    What is essential to ensure after identifying a meningococcal infection?

    <p>Conducting contact tracing and applying prophylaxis.</p> Signup and view all the answers

    For a patient with a suspected dental source leading to a brain abscess, which specimen should be prioritized for analysis?

    <p>Pus from the brain for microbiology and histology.</p> Signup and view all the answers

    Which imaging method is recommended for diagnosing brain infections?

    <p>Contrast CT or MRI.</p> Signup and view all the answers

    What is a likely differential diagnosis for a patient presenting with confusion and seizures, suspected to have a brain abscess?

    <p>Encephalitis, tumour, or stroke.</p> Signup and view all the answers

    What is the expected duration of treatment for a brain abscess depending on clinical response?

    <p>Up to 6 weeks.</p> Signup and view all the answers

    Study Notes

    RCSI Bacterial Meningitis & Brain Abscess Lecture Notes

    • Topic: Bacterial Meningitis & Brain Abscess
    • Lecturer: Professor Karen Burns
    • Date: November 13, 2024
    • Course: Undergraduate Medicine
    • Class: Year 2, Semester 1

    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 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

    • Patient: 18-year-old male, university engineering student
    • Presentation: Unconscious, petechial rash
    • Living Situation: Shares a house with 4 other students
    • Likely Diagnosis: Meningococcal BSI (septicaemia)
    • Recommended Tests: Blood cultures, CSF
    • Treatment: Ceftriaxone/cefotaxime + vancomycin + steroids
    • Other Necessary Actions: Inform public health, contact tracing, prophylaxis

    Clinical Case 2

    • Patient: 45-year-old male engineer
    • Presentation: Low-grade temperature, confused, new-onset seizure
    • Reason for Seeking Care: Suspected dental abscess
    • Differential Diagnoses: Brain abscess, encephalitis, tumor, stroke
    • Potential Source: Dental abscess
    • Tests: Blood cultures, brain pus (microbiology and histology)
    • Treatment: Ceftriaxone/cefotaxime + flucloxacillin + metronidazole

    Where is the Inflammation?

    • Meningitis: Inflammation of the meninges (tissue surrounding the brain and spinal cord)
    • Encephalitis: Inflammation of the brain parenchyma (the actual brain tissue)
    • Meningoencephalitis: Inflammation of both the meninges and the brain parenchyma

    How Bacteria Enter the CSF

    • Haematogenous Spread (most common): From the nasopharynx or other infection site
    • Spread from Adjacent Focus: Sinusitis, Mastoiditis
    • Spread from Nasopharynx via Bony Defect or Head Injury: Cribriform plate (rarely)

    Causative Organisms of Meningitis

    • Bacteria: Severe illness, geographical and age-related differences in common organisms
    • Viruses: Usually a milder illness. Referred to in other lectures.
    • Fungi: Uncommon, immunocompromised patients (e.g., Cryptococcus neoformans)
    • Amoebae: Very uncommon

    Typical Pathogens (non-viral)

    • All ages: Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae type b (Hib), Group B streptococcus, E. coli, other aerobic gram-negative bacilli, Listeria monocytogenes
    • Neonates: Group B streptococcus, E. coli, other aerobic gram-negative bacilli, Listeria monocytogenes
    • Elderly: Streptococcus pneumoniae, Listeria monocytogenes

    Host Factors Increasing Meningitis Susceptibility

    • Asplenia: Increased risk of severe infection with encapsulated bacteria (Hib, S. pneumoniae, N. meningitidis)
    • Diabetes Mellitus & Alcohol Abuse: Increased risk with S. pneumoniae
    • Altered Cell-Mediated Immunity (Immunosuppression): Increased risk of Listeria monocytogenes,Cryptococcus neoformans
    • Skull Fracture/Bony Defect: Increased risk of recurrent S. pneumoniae
    • Inherited Defects in Late Complement Components: Recurrent invasive Neisseria meningitidis infection
    • Pregnancy: Increased risk of invasive disease, including meningitis if Listeria monocytogenes is acquired

    Risk Factors for Bacterial Meningitis

    • Unvaccinated: Against Hib, MenC, MenB, MenACWY, PCV13, and PPV23 vaccination
    • Age: All ages, but risk factors vary by age group and specific microorganisms
    • Living in a Communal Setting: Increases risk. Examples include college dorms or military bases
    • Compromised Immune System: HIV, alcohol abuse, diabetes, immunosuppressant drugs, asplenia
    • Pregnancy: Increases the risk of Listeria monocytogenes infection if exposed via contaminated food
    • Recent History of Infection (especially Respiratory or Ear Infection): Increased risk
    • Contact with Someone with Bacterial Meningitis: Increased risk
    • Head Trauma: Increased risk
    • CSF Otorrhea or Rhinorrhea: Increased risk
    • Travel History: Certain geographical areas have high penicillin resistance in S. pneumoniae
    • Complement Pathway Deficiency, Base of Skull Fracture,

    Causative Organisms: Recap

    • Nisseria meningitidis: Asymptomatic carriage in nasopharynx, highest in 15-20 years. Small minority develop invasive infection. Incubation period typically 1-10 days. Person-to-person transmission.
    • Streptococcus pneumoniae: Normal upper respiratory tract flora. Leading cause of meningitis in adults. May reach the CNS through bloodstream infection, chronic ear or sinus infection, after head trauma, or bony defect at the base of the skull.
    • Haemophilus influenzae type b (Hib): Historically, a major cause of meningitis and epiglottitis in early childhood but vaccination has created a large impact. Still seen in poorly resourced healthcare systems
    • Listeria monocytogenes: Zoonotic. Acquired by ingesting contaminated meat, meat products, vegetables, or dairy products. Pregnant women, neonates, and the elderly are at higher risk.
    • Cryptococcus neoformans: Encapsulated yeast. Soil, bird droppings. Inhaled into the lungs-generally no symptoms; however may cause meningitis when the immune system is compromised, especially in those with HIV infection. Acute bacterial meningitis presentation differences- gradual onset, headache.
    • Leptospira interrogans Zoonotic. Clinical features of leptospirosis which can include meningitis, lymphopcytis in CSF, consideration for renal, or hepatic failure. Clinical clues: occupation

    Clinical Signs in Meningitis

    • Kernig Sign: Pain or limiting extension of the leg when also flexed at the knee and hip
    • Brudzinski Sign: Involuntary flexion of legs when the head/neck is flexed

    Rash Associated With Meningococcal Sepsis

    • Purpuric: Rash of tiny "pin pricks" transforming into purple bruising
    • Non-blanching: Does not fade under pressure. DO THE GLASS TEST!

    What is Sepsis?

    • Infection: triggers
    • Host Response:
    • Organ Dysfunction:

    Complications of Bacterial Meningitis

    • CNS: Hearing loss, subdural abscess, cranial nerve palsies, intellectual problems, hydrocephalus, increased intracranial pressure
    • Outside the CNS: Dissemination and its consequences (e.g., bloodstream infection (BSI), septic shock)

    Antimicrobials Urgently

    • IV antimicrobials, not oral
    • Do not delay! Needed to penetrate the blood-brain barrier (BBB)
    • IV steroids

    Diagnosing Meningitis

    • Clinical Assessment: Mainstay
    • Laboratory Testing: Confirmation of clinical impression
      • Lumbar Puncture (LP) to get CSF microscopy, Gram stain, culture, PCR
      • Blood cultures
      • Blood for PCR

    Radiology

    • Role in Meningitis Diagnosis: Imaging is not usually used for primary diagnosis of meningitis; its findings are not sensitive or specific. Important to consider imaging if LP is unsafe or to see if complication like abscess or ventriculitis exist.
    • When Radiography is Useful: When there is concern about the safety of an LP, to assess for complications such as abscess or ventriculitis, or other intracranial issues.

    Lumbar Puncture (LP)

    • Contraindications: Signs of increased intracranial pressure (ICP), coagulopathy
    • CSF Characteristics: Normal CSF is clear and colourless. Cloudy or turbid CSF suggests bacterial infection.

    Laboratory Diagnosis of Bacterial Meningitis

    • CSF Microscopy: White Blood Cell Count (WCC) and Differential WCC, Gram stain
    • CSF Inoculation: Onto blood and chocolate agar plates: Identification of bacterial growth
    • Blood Cultures: Incubated
    • PCR: Directly on blood and CSF, results are quickly available

    CSF Characteristics in Meningitis

    • Bacterial Meningitis: Very elevated protein, low glucose, raised white cells (primarily neutrophils), specific micro-organisms detected by gram stain and culture and PCR.
    • Viral Meningitis: Elevated protein, normal glucose, raised white cells (lymphocytes), specific virus detected by PCR or other virological tests.
    • Tuberculous Meningitis: Elevated protein, low glucose, raised white cells (primarily lymphocytes), specific bacterium detected by PCR or other microbiological tests.

    Treatment of Bacterial Meningitis

    • Source Control: Surgical drainage (e.g., craniotomy or burr hole)
    • Empiric Antimicrobials: Local guidelines, often including ceftriaxone/cefotaxime, vancomycin, and flucloxacillin in combination with metronidazole.
    • Duration of Therapy: Varies based on the causative microorganism according to microbiology result
    • Steroids: With/before initiation of antibiotics. May reduce complications. Specific studies show this to be particularly important in cases of Hib or Pneumococcal meningitis

    Prevention of Bacterial Meningitis:

    • Vaccination: Highly important. Vaccines are available for N. meningitidis, H. influenzae type b (Hib), and Streptococcus pneumoniae
    • Prophylaxis: Long-term daily oral penicillin is indicated in those with underlying conditions like asplenia and immunosuppression. Prophylaxis is useful for their close contacts also. May also includes rifampicin or ciprofloxacin.

    Summary

    • Bacterial meningitis: Medical emergency; rapid diagnosis is critical
    • Empiric antimicrobials: With steroids and resuscitation, and ICU care where necessary, for patients with meningitis
    • Clinical assessment: Cell count, CSF for microscopy, biochemistry, culture and PCR testing are necessary to assess diagnosis
    • Blood cultures: Necessary for diagnosis
    • Vaccination: Highly effective in preventing bacterial meningitis (e.g., N. meningitidis, H. influenzae type b, Streptococcus pneumoniae).
    • Brain abscess: May mimic tumor or stroke
    • Source control: Surgical drainage is essential when infections in brain parenchyma occur.

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    Test your knowledge on bacterial meningitis through a variety of clinical questions. This quiz covers the routes of infection, symptoms, management strategies, and preventative measures. Additionally, it explores risk factors and differentiates between meningitis and encephalitis.

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