Pathogenesis of Meningitis Infection; Colonization, Invasion into Bloodstream, Entry in Subarachnoid скачать в хорошем качестве

Pathogenesis of Meningitis Infection; Colonization, Invasion into Bloodstream, Entry in Subarachnoid

The pathogenesis of meningitis—particularly bacterial meningitis—is a multi-step process involving microbial invasion, immune evasion, and intense inflammation within the central nervous system (CNS). Here's a breakdown of how it unfolds: 🦠 Step-by-Step Pathogenesis Colonization of Mucosal Surfaces Pathogens like Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae first colonize the nasopharynx or respiratory tract. They use adhesins and pili to attach to epithelial cells and evade mucosal defenses. Invasion into the Bloodstream After breaching the mucosal barrier, bacteria enter the bloodstream. They resist phagocytosis and complement-mediated killing using capsules, IgA proteases, and other virulence factors. Crossing the Blood-Brain Barrier (BBB) Bacteria penetrate the BBB via: Transcellular traversal (through endothelial cells) Paracellular traversal (between cells) Trojan horse mechanism (inside infected immune cells) Once inside the subarachnoid space, they multiply rapidly due to limited immune surveillance. CNS Inflammation Bacterial components (e.g., lipopolysaccharide, peptidoglycan) trigger a massive cytokine response. This leads to: Increased vascular permeability Cerebral edema Leukocyte infiltration Elevated intracranial pressure Neuronal Injury The inflammatory response causes: Ischemia Oxidative stress Excitotoxicity Direct cytotoxicity from immune cells 🔬 Key Players in the Immune Response TNF-α, IL-1β, and IL-6: Major pro-inflammatory cytokines Neutrophils: First responders that release enzymes and reactive oxygen species Microglia: CNS-resident immune cells that amplify inflammation 🧠 Clinical Implications Symptoms like fever, headache, neck stiffness, and altered mental status stem from the inflammatory damage and increased intracranial pressure. Rapid diagnosis and treatment are critical to prevent complications like seizures, hearing loss, or brain herniation. #Pathogenesis #Meningitis #Infection