What are the causes and signs/symptoms of sepsis?

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Last updated: June 23, 2025View editorial policy

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From the Guidelines

Sepsis is a life-threatening condition caused by the body's extreme response to an infection, and prompt medical attention is crucial to prevent mortality and morbidity. The most common causes of sepsis include bacterial infections, particularly pneumonia, urinary tract infections, abdominal infections, and bloodstream infections, though viral, fungal, and parasitic infections can also trigger sepsis 1. Risk factors for sepsis include advanced age, weakened immune systems, chronic medical conditions, and recent hospitalizations or invasive procedures 1.

Signs and Symptoms of Sepsis

The signs and symptoms of sepsis follow a progression that can rapidly become dangerous. Early signs include:

  • Fever or low body temperature
  • Rapid heart rate
  • Rapid breathing
  • Confusion or disorientation As sepsis progresses, patients may develop:
  • Difficulty breathing
  • Abdominal pain
  • Decreased urination
  • Mottled skin
  • Extremely low blood pressure (septic shock) 1.

Organ Dysfunction and Sepsis

The hallmark of sepsis is organ dysfunction resulting from the body's dysregulated response to infection, which occurs because the immune system releases chemicals that trigger widespread inflammation, leading to blood clots, leaky blood vessels, and impaired blood flow that damages organs 1.

Importance of Early Recognition and Treatment

Recognizing these signs early is essential, as mortality increases significantly with each hour treatment is delayed 1. The use of NEWS2 for stratifying risk of severe illness or death from sepsis can help guide the urgency of antibiotic prescribing and source control 1. Prompt medical attention is crucial, as sepsis requires immediate treatment with antibiotics, intravenous fluids, and sometimes vasopressors to maintain blood pressure 1.

From the Research

Causes of Sepsis

  • Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection 2, 3, 4, 5.
  • Sepsis can be caused by a broad range of pathogens, including bacterial, fungal, or viral pathogens 2, 3, 6.
  • Bacterial infections represent the majority of sepsis cases, but up to 42% of sepsis presentations are culture negative, suggesting a non-bacterial cause 2.
  • Almost any virus can cause sepsis in vulnerable patients, such as neonates, infants, and other immunosuppressed groups 2.
  • Leading causative agents of sepsis include bacterial pathogens such as Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, and Streptococcus pyogenes, along with fungal pathogens of the Candida species 6.

Signs and Symptoms of Sepsis

  • The clinical manifestations of sepsis can include an altered mental status, dyspnea, reduced urine output, tachycardia, and hypotension 3.
  • Sepsis occurs in two concurrent phases, which consist of an initial immune activation phase followed by a chronic immunosuppressive phase, leading to immune cell death 4.
  • The hosts immune system may not fully recover, leading to ongoing complications proceeding the initial infection 4.
  • Sepsis is characterized by sustained excessive inflammation and immune suppression 5.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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