Infection is the invasion and multiplication of microorganisms — such as bacteria, viruses, fungi, or parasites — in the body, which may cause tissue damage and trigger an immune response.
Key Points: Causative agents: Pathogens (e.g., Streptococcus, influenza virus, Candida, Plasmodium)
Routes of entry: Skin, respiratory tract, gastrointestinal tract, urogenital tract, or bloodstream
Types:
Localized (e.g., skin abscess)
Systemic (e.g., sepsis)
Acute vs. Chronic
Nosocomial (hospital-acquired) vs. community-acquired
Signs/Symptoms: Fever, inflammation, pain, pus, malaise, organ dysfunction (depending on site)
Diagnosis: Cultures, serologies, PCR, imaging
Treatment: Antimicrobials (antibiotics, antivirals, antifungals, antiparasitics), supportive care