Bacteria can enter the blood and lymph through breaks in skin or mucosa, or spread from localized infections. This lesson explains how a usually limited bacteremia can become life-threatening sepsis and compares toxic shock syndromes.
Bacteremia is the presence of bacteria in the bloodstream. Small exposures, including minor wounds, insect bites, or gum irritation during tooth brushing, can cause brief, low-level bacteremia that is often undetectable and cleared by the immune system. A localized infection can also spread into blood and lymph.
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How does sepsis differ from bacteremia?
Bacteremia is the presence of bacteria in the bloodstream; sepsis is a dangerous systemic response to infection.
How can excessive cytokine release contribute to septic shock?
Systemic IL-1 and TNF-α can promote vasodilation, vascular leak, edema, and clot formation, contributing to hypotension and impaired organ function.
What causes staphylococcal toxic shock syndrome?
Some Staphylococcus aureus strains produce TSST-1, a superantigen that can trigger excessive immune activation.
How does streptococcal toxic shock-like syndrome differ from staphylococcal TSS?
STSS is caused by Streptococcus pyogenes and is often more severe, with frequent bacteremia, necrotizing fasciitis, and higher mortality.
What is puerperal sepsis, and how can its risk be reduced?
It is infection arising after childbirth; antiseptic practices during delivery and careful handwashing by health-care workers reduce risk.
Quiz questions
Which test is central to diagnosing infectious arthritis?Answer: Aspiration and analysis of synovial fluid
How do bacteria commonly reach bone in children with osteomyelitis?Answer: They spread to bone through the bloodstream.
What can initiate acute rheumatic fever?Answer: An immune response after Streptococcus pyogenes pharyngitis
Which condition creates a favorable environment for Clostridium perfringens to cause gas gangrene?Answer: Poorly perfused, oxygen-poor tissue
Which form of plague can spread directly between people through infectious aerosols?Answer: Pneumonic plague
Based on Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.