Related Experiment Video
Updated: Aug 15, 2026

Knee Arthrocentesis in Adults
Published on: February 25, 2022
[Arthritis and infections]
R Cimaz1, E Meregalli, M Biggioggero
1Clinica Pediatrica De Marchi, ICP, Milan. rolando.cimaz@unimi.it
Abstract:
Arthritis caused by infectious agents can be secondary to direct invasion of the joint space or to immune mechanisms (subsequent to or concomitant to an infection). Septic arthritis refers to a situation when bacteria can be cultured in synovial fluid. Arthritis can complicate for example meningococcemia or infection by Neisseria gonorrhoeae or Haemophilus influenzae. Reactive (postinfectious) arthritides are an important diagnostic category within a pediatric rheumatology practice. Yersinia and, less frequently, Salmonella, play an important role in postdiarrheal disorders. The arthritis that can ensue is usually oligoarticular and occurs 1-2 weeks after the enteric infection. Reiter's syndrome, rare in the pediatric age, is characterized by the triad urethritis-conjunctivitis-arthritis. Postviral arthritides can occur after a variety of viral infections, including Parvovirus B19, rubella, and others (e.g. hepatitis B, Epstein-Barr virus, chickenpox, mumps). Especially in patients with acute arthritis, the presence of preceding infections should always be investigated. Although the majority of postinfectious arthritides are self-limiting in nature and do not require specific treatment, conditions such as Lyme borreliosis and rheumatic fever can be associated with significant morbidity, and sometimes can be even lethal.
Insights
Infectious agents can cause arthritis through direct joint invasion or immune responses. Investigating preceding infections is crucial for diagnosing and managing various forms of infectious and postinfectious arthritis.
Area of Science:
- Rheumatology
- Infectious Diseases
- Pediatric Rheumatology
Context:
- Infectious agents can lead to arthritis via direct joint invasion or immune-mediated mechanisms.
- Septic arthritis involves bacteria in synovial fluid, complicating infections like meningococcemia.
- Reactive (postinfectious) arthritides are significant in pediatric rheumatology, often following enteric or viral infections.
Purpose:
- To explore the diverse causes and presentations of infectious and postinfectious arthritis.
- To highlight the diagnostic importance of preceding infections in acute arthritis cases.
- To differentiate between self-limiting postinfectious arthritides and those with significant morbidity.
Summary:
- Arthritis can arise from direct bacterial invasion (septic arthritis) or immune responses to infections (reactive arthritides).
- Common causes include bacteria (Neisseria gonorrhoeae, Haemophilus influenzae) and viruses (Parvovirus B19, rubella).
- Postinfectious arthritis typically presents 1-2 weeks after enteric infections (Yersinia, Salmonella) or viral illnesses, often oligoarticular.
Impact:
- Early investigation of preceding infections is vital for accurate diagnosis of acute arthritis.
- While many cases are self-limiting, conditions like Lyme borreliosis and rheumatic fever require specific management due to potential severity.
- Understanding infectious triggers aids in managing pediatric rheumatologic conditions.
Related Concept Videos
Inflammation
Acute Inflammation III: Local and Systemic Effects
Factors Affecting the Risk of Infection
The integrity and count of the white blood cells help the body resist pathogens and fight infection. When impaired, it reduces the body's resistance to pathogens. The acidic pH levels of the gastrointestinal, genitourinary tracts, and skin create...
Chronic Inflammation: Introduction
Inflammation: Introduction
Infectious Diseases and Their Occurrence