SEPTIC ARTHRITIS

Septic arthritis, also called infectious arthritis, is a serious condition where an infection invades your joints, causing inflammation. This inflammation affects the cartilage (the smooth, rubbery tissue lining your joints) and the synovial fluid (the lubricating fluid inside your joints). The culprit behind this infection can be bacteria, viruses, or even fungi, often traveling in your bloodstream from another part of the body. While large joints like your hips and knees are more prone to septic arthritis, it can affect any joint, including your shoulders and ankles.

It’s important to remember that “arthritis” is a general term for joint inflammation, and there are many types, such as osteoarthritis (wear-and-tear arthritis), rheumatoid arthritis (an autoimmune disease), psoriatic arthritis (linked to the skin condition psoriasis), and gout (caused by uric acid crystal buildup). Interestingly, even though arthritis is often associated with older adults, septic arthritis is actually more common in children.

Septic arthritis, an infection in your joints, can strike various joints, but some are more vulnerable than others. Here’s a breakdown:

Large Lower Body Joints: Hips, knees, and ankles in adults are most susceptible due to their size and frequent use.
Children and Hips: Kids are more likely to develop septic arthritis in their hips.
Injection Drug Users: In this group, the infection often targets the joints connecting the lower spine and pelvis (sacroiliac) and the joint between the collarbone and breastbone (sternoclavicular).

While most cases involve a single infected joint, sometimes multiple joints can be affected. This is more common with certain bacteria, like Neisseria, compared to Staphylococcus, the usual culprit.

Who gets septic arthritis?

Children are more susceptible, especially boys between 2 and 3 years old. However, adults can also develop septic arthritis.

Septic arthritis spread

Septic arthritis isn’t contagious, meaning you can’t catch it directly from someone else. However, the bacteria that cause this painful joint infection can be spread through close contact. Common culprits include Staphylococcus aureus (staph), methicillin-resistant Staphylococcus aureus (MRSA), and Neisseria gonorrhoeae (the bacteria that causes gonorrhea). If left untreated, the infection causing septic arthritis can travel through your bloodstream and infect other body parts, leading to a life-threatening condition called sepsis.

Causes of septic arthritis

Septic arthritis occurs due to an infection, which can be caused by various pathogens such as bacteria, fungi, mycobacteria, viruses, and other microorganisms. Typically, the infection originates elsewhere in the body and spreads through the bloodstream to reach the joint. Here are some specific organisms known to cause septic arthritis:

Staphylococcus aureus, commonly referred to as staph, is the leading cause of septic arthritis in both children and adults.
Methicillin-resistant Staphylococcus aureus (MRSA): MRSA is a strain of staph infection resistant to certain antibiotics. Individuals with higher risks of developing this infectious arthritis from MRSA include intravenous drug users, those with HIV (human immunodeficiency virus infection), or those with diabetes.
Groups A and B streptococci: Streptococci, a type of bacteria, can also lead to this infectious arthritis. Elderly individuals and those with chronic conditions like diabetes and cirrhosis are more susceptible to septic arthritis caused by streptococci.
Neisseria gonorrhoeae: This bacterium causes gonorrhea, a sexually transmitted infection (STI). Individuals with gonorrhea can develop gonococcal arthritis, a form of septic arthritis.
Neisseria meningitidis (meningococcus): This bacterium is responsible for meningitis, an inflammation of the protective membranes covering the brain and spinal cord. While rare, septic arthritis can result from a Neisseria meningitidis infection.

Among these pathogens, Staphylococcus aureus stands out as the most prevalent bacteria causing septic arthritis, accounting for approximately 37% to 56% of cases.

Symptoms

Here are the main symptoms to watch out for:

Severe pain and tenderness in one joint
Swelling and warmth around the joint
Difficulty moving the joint
Feeling feverish or having chills
Not wanting to put any weight on the joint (if it’s in your leg or foot)

Risk factor

The risk factors for developing septic arthritis vary between children and adults.

For Children:

Age: Newborns have a higher risk due to their still-developing immune systems.
Hemophilia: Children with hemophilia, a genetic bleeding disorder, are at increased risk.
Weakened immune system: Conditions like sickle cell anemia and HIV compromise the immune system, elevating the risk.
Chemotherapy: Chemotherapy weakens immunity, making children undergoing treatment more vulnerable.

For Adults:

Age: Adults over 80 are at higher risk.
Rheumatoid arthritis (RA) or osteoarthritis: existing joint damage increases susceptibility.
HIV: HIV weakens the immune system, making infections, including septic arthritis, more likely.
Diabetes: High blood sugar weakens immunity, raising the risk of infection and septic arthritis.
Skin infections: Infections elsewhere in the body can lead to septic arthritis.
Recent joint surgery: Surgical wounds increase susceptibility to infection.
Artificial joints: prosthetic joints are more susceptible to infection than natural joints.
Injection drug use: needle use introduces bacteria, elevating the risk.
Sexual activity: Unprotected sex, particularly with Neisseria gonorrhoeae, increases the risk of gonococcal arthritis, a form of septic arthritis.

Diagnosing Septic Arthritis

Diagnosing this infectious arthritis typically involves several tests and procedures:

Synovial fluid aspiration: Your healthcare provider will likely withdraw synovial fluid from the affected joint using a needle in a procedure called aspiration. This fluid will be examined in a laboratory to detect the presence of bacteria, which confirms the diagnosis of septic arthritis.
Blood tests: Blood tests may be conducted to assess your body’s immune response to infection and to rule out other potential issues.
X-rays: X-rays utilize radiation to produce images of bones. They can reveal widened joint spaces and soft tissue swelling, which are indicative of septic arthritis.
Ultrasound: Ultrasound imaging employs sound waves to visualize the inside of the body. It helps assess joint swelling and aids in guiding the aspiration procedure to collect joint fluid.
MRI (Magnetic Resonance Imaging): MRI scans generate detailed images of organs and bones using a combination of magnets, radio waves, and a computer. MRI can detect early signs of septic arthritis and provide additional information about joint damage.

Treatment for septic arthritis

Treatment for this infectious arthritis typically involves a combination of approaches tailored to the individual case:

Surgery: In most cases, surgical intervention is necessary to remove inflamed tissue through a procedure known as surgical debridement. This is often accompanied by the administration of intravenous (IV) antibiotics.
Antibiotics: Antibiotic therapy is essential for treating this infectious arthritis. Antibiotics may be administered intravenously or orally, depending on the severity of the infection.
Joint fluid drainage: Fluid from the affected joint may be drained using a fine needle in a procedure called aspiration. This may need to be repeated as part of the recovery process.
Physical therapy: this therapy is typically recommended to restore joint function and prevent muscle weakness around the affected joint.
Removal of artificial joint: If this infectious arthritis occurs in an artificial (prosthetic) joint, surgical removal of the artificial joint may be necessary. It may be replaced temporarily with a joint spacer containing antibiotic cement. Eventually, the artificial joint can be replaced once the infection is under control.

Recovery time

The duration of healing varies depending on factors such as the underlying cause of the infection and the individual’s overall health. Antibiotic treatment may last several weeks, and the healing process may be prolonged if the infection has caused damage to the joint and surrounding tissues.

Prevention

To reduce the risk of this infectious arthritis, consider the following preventive measures:

Maintain wound hygiene: Keep cuts and wounds clean to prevent infection. Promptly clean any wounds and monitor for signs of infection, such as redness, warmth, or pus. Seek medical attention if signs of infection develop.
Manage chronic health conditions: If you have conditions like diabetes or AIDS, diligent management is crucial to supporting overall health and immune function. Follow treatment plans and attend regular medical appointments to monitor and control your condition effectively.
Practice safe sex: Engage in safe sex practices to minimize the risk of sexually transmitted infections (STIs) like gonorrhea, which can lead to gonococcal arthritis. Always use condoms or dental dams and communicate openly with sexual partners about STI history.
Avoid drug abuse: Injection drug use can introduce harmful bacteria and increase the risk of infections, including septic arthritis. Only use medications as prescribed by healthcare professionals and seek help if struggling with substance abuse.

Complications of septic arthritis

Complications associated with this infectious arthritis include:

Chronic pain
Osteomyelitis (bone inflammation)
Osteonecrosis (bone tissue death)
Leg length discrepancy
Sepsis (systemic inflammation)
Death

When should I see a doctor?

If you experience symptoms such as joint pain, fever, warmth, redness, or limited mobility, it’s vital to contact your healthcare provider or seek immediate medical care. This infectious arthritis requires prompt antibiotic treatment to prevent serious consequences.

Prognosis

The prognosis (outlook) for this infectious arthritis depends on several factors:

Type of causative organism: The type of bacteria or organism responsible for the infection influences the prognosis. Some bacteria, like MRSA, pose greater treatment challenges.
Duration of infection: The longer the infection persists, the higher the likelihood of joint damage.
Age and overall health: Younger, healthier individuals may have better outcomes compared to those with weakened immune systems or underlying health conditions.

Septic arthritis FAQs

Can the arthritis heal without treatment?

This infectious arthritis cannot resolve on its own as it is caused by an infection. Prompt medical attention is crucial to preventing serious complications and potential life-threatening situations. If symptoms of this infectious arthritis are present, contacting a healthcare provider or seeking care at the nearest hospital is essential for timely treatment and management.

How common is septic arthritis?

Septic arthritis is an uncommon infection in the joint that causes serious problems if left untreated. It affects only a few people out of every hundred thousand each year. While uncommon, it’s important to see a doctor right away if you experience symptoms because early treatment helps prevent permanent damage to the joint.

What’s the mortality rate for septic arthritis?

This infectious arthritis can indeed be fatal, with a mortality rate ranging from 7% to 15%, despite antibiotic treatment. Prompt medical attention is crucial to preventing life-threatening complications.

What is the difference between septic arthritis and osteomyelitis?

Osteomyelitis is an infection of the bone, while septic arthritis involves inflammation of the joint’s cartilage and synovial fluid due to infection.
Both conditions share similar symptoms, including pain, tenderness, and swelling in the affected area. Septic arthritis can lead to osteomyelitis, and both may coexist.
Diagnostic tests are necessary to differentiate between the two conditions, and both require medical treatment.

Distinguish between septic arthritis and gout

Gout is a form of inflammatory arthritis caused by uric acid crystals, while septic arthritis results from joint infection.
Symptoms such as joint inflammation, redness, and swelling can overlap between the two conditions.
Medical evaluation and tests are needed to determine the underlying cause of symptoms and initiate appropriate treatment.

Sources

Medline Plus
Clevland clinic
WebMD
JAMA
University of Maryland Medical Center