CNS Infections and Related Topics Flashcards

Vocabulary flashcards based on lecture notes about CNS infections, bloodstream infections, malaria, and HIV/AIDS.

Meningitis

Serious infection of the meninges (protective membranes of the brain and spinal cord). Classified as viral, bacterial, fungal, parasitic, or non-infectious.

Clinical Triad (Meningitis)

Fever, headache, and neck stiffness; classic symptoms of meningitis.

Lumbar Puncture (LP)

Procedure involving needle insertion into the lumbar spine to collect cerebrospinal fluid for analysis.

Waterhouse-Friderichsen Syndrome

Life-threatening complication of bacterial meningitis, involving DIC, acute adrenal insufficiency, and tissue necrosis.

Bloodstream Entry (CNS Infections)

Inflammation-induced increase in capillary permeability, allowing pathogens to enter the cerebrospinal fluid from the bloodstream.

Shunts (CNS Infections)

Artificial entry route for CNS infections, often involving biofilm-forming bacteria like Staph. epidermidis.

VP Shunt

Surgical insertion of tubing to drain excess CSF from the brain ventricles to the peritoneum.

Acute Pyogenic Meningitis

Rapid onset, pus-forming infection of the meninges, requiring urgent diagnosis.

Group B Streptococcus (GBS)

Gram-positive cocci in chains, a common cause of neonatal meningitis, acquired during birth.

Listeria monocytogenes

Gram-positive bacilli, foodborne pathogen causing meningitis, especially in pregnant women and neonates; spreads via actin polymerization.

Neisseria meningitidis (Meningococcus)

Gram-negative diplococci (kidney bean-shaped), a major cause of meningitis in children and young adults, transmitted via respiratory droplets.

Purpuric Rash

Non-blanching, purple-red blotches with irregular borders; a sign of capillary leak and inflammation in meningococcal disease.

Aseptic Meningitis

Non-purulent meningitis, often caused by viruses, characterized by clear CSF.

Enteroviruses

Includes poliovirus; causes summer outbreaks; transmitted via fecal contamination in pools; resistant.

Mycobacterium tuberculosis (TB)

Acid-fast bacilli, cause of atypical, chronic meningitis; stain red with acid-fast stain.

Cryptococcus neoformans

Yeast with a large anti-phagocytic capsule, causing meningitis; diagnosed using India ink prep.

Naegleria fowleri

Free-living amoeba, causing Primary Amoebic Meningoencephalitis (PAM); enters via cribriform plate during swimming in warm freshwater.

Encephalitis

Inflammation of the brain parenchyma, more severe than meningitis, often caused by viruses.

Japanese Encephalitis Virus (JEV)

Spread via mosquitoes; severe outbreaks with high mortality; detected in Australia due to increased rainfall.

Rabies

Source of rabies; transmitted via saliva of infected animals; clinical signs include hydrophobia and agitation.

Toxoplasma gondii

Parasite transmitted via cat feces or undercooked meat; causes congenital toxoplasmosis.

Prion Diseases (e.g., CJD)

Infectious agents caused by misfolded proteins (prions); result in spongiform encephalopathy; resistant to sterilization.

Bacteremia

Presence of bacteria in the bloodstream, but not actively growing; usually transient and cleared by the immune system.

Septicemia (Sepsis)

Bacteria actively multiplying in the blood, leading to systemic inflammation and toxicity.

Lymphangitis

Red streaks spreading from an infected wound, indicating bacterial spread via the lymphatic system.

Endocarditis

Mouth flora; follows valve damage; produces heart murmurs; colonize damaged heart valves and form vegetations.

Gram-Negative Bacteria

Contains lipopolysaccharide (LPS) aka endotoxin; highly inflammatory; leads to vasodilation, hypotension, and higher mortality rate. Examples: E. coli, Klebsiella, Pseudomonas.

Malaria

a parasitic disease caused by Plasmodium species, transmitted via the bite of a female Anopheles mosquito.

Plasmodium falciparum

Most severe form of malaria; causes cerebral malaria; drug-resistant strains common; responsible for most deaths.

P. vivax

Can remain dormant in the liver (hypnozoites); causes relapsing malaria.

HIV/AIDS

HIV: Human Immunodeficiency Virus; AIDS: Acquired Immunodeficiency Syndrome — the clinical syndrome that may result from untreated HIV

Immunopathology of HIV

HIV targets CD4+ Helper T cells; Loss of helper T cells = impaired cell-mediated and humoral immunity

AIDS definition

AIDS = CD4 count < 200 cells/μL

Classification & Origin of HIV

HIV-1: Main global type (most common); HIV-2: Less transmissible, found primarily in West Africa; Simian Immunodeficiency Virus (SIV): Origin of HIV via zoonotic transmission from monkeys (likely via bushmeat handling)

HAART

Highly Active Anti-Retroviral Therapy; Usually a combination of 3 or more drugs: Reverse Transcriptase Inhibitors, Protease Inhibitors, Integrase Inhibitors, Fusion/Entry Inhibitors

Meningoencephalitis

Infection of brain parenchyma + meninges

Cerebrospinal Fluid Analysis

Test used to differentiate bacterial vs viral meningitis. Measures WBC count. Protein and glucose levels

N. Meningitidis

Vaccine preventable. Gram negative bacteria that causes petechial rash and potential Waterhouse-Friderichsen Syndrome

AIDS

HIV + opportunistic infection. CD4 count <200

HIV Transmission

Unprotected sex, IV drug use, mother to child

HIV Pathogenesis

Targets CD4+ T cells, leading to immunosuppression

P. vivax and P. ovale

Type of malaria with dormant liver stage

Malaria Life Cycle

Infects mosquitoes (sexual) and humans (asexual)

Endocarditis

Infection of the inner lining of the heart chambers and valves

Common causes of Endocarditis

S. aureus, Viridans streptococci, S. epidermidis

Meningoencephalitis

Infection of brain parenchyma + meninges

Cerebrospinal Fluid Analysis

Test used to differentiate bacterial vs viral meningitis. Measures WBC count. Protein and glucose levels

N. Meningitidis

Vaccine preventable. Gram negative bacteria that causes petechial rash and potential Waterhouse-Friderichsen Syndrome

AIDS

HIV + opportunistic infection. CD4 count <200

HIV Transmission

Unprotected sex, IV drug use, mother to child

HIV Pathogenesis

Targets CD4+ T cells, leading to immunosuppression

P. vivax and P. ovale

Type of malaria with dormant liver stage

Malaria Life Cycle

Infects mosquitoes (sexual) and humans (asexual)

Endocarditis

Infection of the inner lining of the heart chambers and valves

Common causes of Endocarditis

S. aureus, Viridans streptococci, S. epidermidis

Case Study: Meningitis

A 25-year-old male presents with fever, headache, and stiff neck. CSF analysis shows high WBC count and Gram-negative diplococci.

Case Study: Endocarditis

A patient with a history of IV drug use presents with fever, new heart murmur, and blood cultures positive for S. aureus.

Case Study: AIDS

Patient presents with fatigue, weight loss, and persistent cough. CD4 count is 150. Diagnosed with Pneumocystis jirovecii pneumonia.

Case Study: Malaria

A traveler returns from a malaria-endemic region with fever, chills, and headache. Blood smear shows Plasmodium falciparum.