Information on Infectious Arthritis. 

 May 7, 2024

By  Linda Rook



Infectious arthritis, also known as septic arthritis, is a serious problem in both rheumatology and infectious diseases. It happens when germs invade a joint, causing inflammation that can harm joint health movement, and even overall health. It can come from bacteria, viruses, fungi, or parasites, each posing its own challenges for diagnosis and treatment.

Why it matters: Infectious arthritis is where rheumatology and infectious diseases meet, showing how the body's immune response interacts with germs. It's not just about the affected joint; it can cause other problems and even be life-threatening if not treated quickly and correctly.

In this blog I shall explore the various germs that cause infectious arthritis, and what makes some people more likely to get it, like weakened immune systems or joint injuries. I shall also talk about the symptoms, such as pain, swelling, fever and how doctors diagnose it using exams, tests, and scans. Then into the treatments like antibiotics, draining the joint, managing pain, and rehab to keep the joint working.

The next section will show you the Prevention is key: this will go through stress and the importance of preventing infectious arthritis through good hygiene, vaccines, and other precautions.

The last one is team effort: beating infectious arthritis takes everyone such as doctors, researchers, policymakers, and communities to work together, making life better for those affected.

Causes of Infectious Arthritis

Bacterial Infections

Bacterial infections are the main reason for infectious arthritis, causing most cases. There are different bacteria that can lead to septic arthritis, but the most common ones are Staphylococcus aureus and Streptococcus species.

1.    Staphylococcus aureus: This germ often causes skin and soft tissue infections. It can get into the bloodstream through wounds, surgeries, or catheters, and then reach the joints, causing inflammation. Staphylococcus aureus can be tough to treat because it can resist many antibiotics, including the difficult-to-treat MRSA.


2.    Streptococcus species: Various types of Streptococcus, like Streptococcus pyogenes (group A Streptococcus) and Streptococcus pneumoniae, can also cause septic arthritis. These infections often start in the throat or respiratory system and then spread to the joints through the bloodstream.

3.    Other Bacterial Pathogens: There are other bacteria like Neisseria gonorrhoea (which causes gonorrhoea), Escherichia coli, Pseudomonas aeruginosa, and Haemophilus influenzae that can infect joints, especially in certain groups of people or after specific exposures.

virus pathogen antibody

Viral Infections.

Viral Infections: Viral infections are not as common as bacterial ones in causing infectious arthritis, but they can still cause significant joint inflammation. Viruses can directly infect joint tissues or trigger immune responses that lead to arthritis.

1.    Hepatitis C Virus (HCV): Chronic HCV infection can cause a type of arthritis called arthralgia syndrome, which includes joint pain and swelling. Exactly how HCV causes joint inflammation isn't fully understood, but it likely involves immune responses and autoimmune reactions.

2.    Human Immunodeficiency Virus (HIV): HIV infection can cause various rheumatic problems, including HIV-associated arthritis. This condition leads to symmetric polyarthritis, which can look like other autoimmune arthritis types. Also, people with HIV have a higher risk of getting septic arthritis from opportunistic infections.

3.    Parvovirus B19: Parvovirus B19 infection can lead to joint problems, especially in children and young adults. It causes symmetric arthritis, mainly in the small joints of the hands and feet. While this arthritis usually goes away on its own, it can be very painful during the acute phase.

Fungal Arthritis

Fungal Arthritis: Fungal arthritis isn't as common as bacterial or viral arthritis, but it can happen, especially in people with weakened immune systems or if fungi get directly into the joint.

1.    Candida species: Candida albicans and other Candida fungi can cause infections in people with weakened immune systems. Fungal arthritis usually happens because of widespread Candida infections, especially in those with IV catheters or on strong antibiotics.

2. Aspergillus species: Aspergillus molds are everywhere in the environment and usually cause lung problems. But in severely immunocompromised people, like those getting stem cell transplants or long-term steroids, Aspergillus can spread and cause arthritis.

Parasitic Infections.

Parasitic Infections: Parasites rarely cause infectious arthritis but can be found in specific areas or in people who've traveled to those places. Parasites can infect joints through the bloodstream or direct contact.

1.    Toxoplasma gondii: This parasite usually causes mild illness in healthy people, but in those with weak immune systems, like people with HIV or organ transplants, it can spread and affect the joints.

Parasitic infections

2.    Filarial Worms: These worms cause lymphatic filariasis, common in tropical regions. While joint problems aren't typical with this infection, the body's immune response to the worms' antigens can lead to reactive arthritis.

Risk Factors for Infectious Arthritis:

Immunocompromised States:

1.    HIV/AIDS: People with HIV have a weakened immune system, making them more likely to get infectious arthritis. They can develop arthritis that looks like rheumatoid arthritis or get joint infections from other infections.

2.    Immunosuppressive Therapy: Patients on drugs that weaken the immune system, like steroids or biologics, for conditions like rheumatoid arthritis or after organ transplants, are more prone to infections, including infectious arthritis.

3.    Underlying Medical Conditions: Some conditions like diabetes, kidney disease, cancer, or liver disease can weaken the immune system, making it harder to fight off infections like infectious arthritis.

Child with a fever.

Joint Trauma or Surgery:

1.    Joint Injuries: Damage to a joint, like fractures or cuts, can let bacteria in, causing septic arthritis.

2.    Orthopaedic Procedures: Surgeries or injections into joints can introduce bacteria, leading to infectious arthritis, even with infection control measures.


1.    Infants and Children: Kids have higher infection risk because of their developing immune systems. Septic arthritis in this group often affects big joints like the hip or knee.

2.    Elderly: Older adults are more vulnerable due to age-related immune changes and other health problems. Their septic arthritis symptoms may not be typical, and it can be more severe.

Lifestyle Factors:

1.    Intravenous Drug Use (IVDU): People who inject drugs have a higher risk because they can introduce germs directly into their bloodstream.

2.    High-Risk Sexual Behaviour: Certain STIs, like gonorrhoea, can cause septic arthritis if untreated. Having multiple partners or a history of STIs increases the risk.

Chronic Joint Conditions:

1.    Rheumatoid Arthritis (RA): People with RA have a higher risk of infectious arthritis because of their autoimmune disease and the immune-suppressing effects of RA drugs. The joint damage and inflammation in RA make it easier for bacteria to cause infection.

2.    Osteoarthritis (OA): Even though OA is mainly wear-and-tear on joints, joint injuries from OA or injections for pain can raise the risk of infectious arthritis. Plus, other health issues like diabetes or obesity in OA patients can make it worse.

Environmental and Occupational Exposures:

1.    Healthcare Workers: People in healthcare, especially those working directly with patients, face more exposure to germs that cause septic arthritis. Following infection control rules is crucial for lowering this risk.

2.    Outdoor Workers: Jobs involving outdoor work or contact with soil, water, or animals—like farming or gardening—can expose people to infection sources, raising the risk of infectious arthritis.

Symptoms: Now, let us talk about the signs of infectious arthritis, looking at what patients might experience:

Farmers outdoor workers ( cows)

Joint Pain:

1.    Intensity: Infectious arthritis usually brings severe joint pain, ranging from mild discomfort to severe agony. The pain might stay or get worse with movement or touching the joint.

2.    Location: It depends on which joint is infected, but common ones include the knee, hip, shoulder, wrist, and ankle. Sometimes, multiple joints hurt at once, especially with widespread infections.

Driving with painful back.

Joint Swelling and Warmth:

1.    Swelling: The infected joint often swells up from fluid build-up, making it look or feel full. How much it swells depends on how bad the infection is.

2.    Warmth: The inflamed joint can feel warmer than usual because of increased blood flow as the body fights the infection.

Limited Range of Motion:

1.    Stiffness: Infectious arthritis can make the joint stiff, making it hard to move normally. Patients might struggle to bend or straighten the joint, especially if it's swollen and painful.

2.    Functional Impairment: As inflammation worsens, it can make it tough to do everyday tasks like walking or using hands. In severe cases, the joint might not move at all.

Systemic Symptoms:

1.    Fever: Many people with infectious arthritis get a fever, usually not too high but it can be worse with severe infections. Fever shows the body is fighting infection.

2.    Chills: Patients might shiver or have chills along with fever as the body tries to warm up to fight infection.

Skin Changes:

1.    Redness: The infected joint might look red or flushed from inflammation, showing increased blood flow.

2.    Warmth: The skin around the joint might feel warm too, from increased blood flow caused by inflammation.

Other Symptoms:

1.    Fatigue: Infection and inflammation can make patients feel tired or sick, even after joint symptoms improve.

2.    Generalized Symptoms: Depending on what's causing the infection, patients might have other symptoms like rash, mouth sores, breathing problems, or stomach issues, giving clues to the infection type.

Diagnosis of Infectious Arthritis:

Clinical Evaluation:

1.    Medical History: The doctor will ask about recent infections, joint injuries, surgeries, and existing health conditions.

2.    Symptom Assessment: Symptoms like joint pain, swelling, stiffness, fever, and overall feeling are carefully checked.

3.    Physical Examination: The doctor looks for signs of joint inflammation, like swelling, warmth, tenderness, and limited movement. They also check for any other signs of infection.

Laboratory Tests:

1.    Blood Tests:

•     Complete Blood Count (CBC): Checks for high white blood cell count, indicating infection.

•     C-reactive Protein (CRP) and Erythrocyte Sedimentation Rate (ESR): Shows inflammation levels.

•     Blood Cultures: Tests for bacteria in the blood.

2.    Joint Fluid Analysis:

•     Synovial Fluid Examination: Analyses fluid from the affected joint for infection markers and bacteria.

3.    Microbiological Tests:

•     Culture and Sensitivity Testing: Identifies the infecting organism and the best treatment.

Blood Test

Imaging Studies:

1.    X-rays: Shows joint damage or complications like osteomyelitis.

2.    Ultrasound: Checks for joint fluid and inflammation.

3.    Magnetic Resonance Imaging (MRI): Provides detailed images of soft tissues and detects early joint problems.

Differential Diagnosis: Other conditions with similar symptoms, like gout or autoimmune arthritis, need to be ruled out.

Treatment of Infectious Arthritis:

Antibiotic Therapy:

1.    Empirical Antibiotics: Start broad-spectrum antibiotics right away while waiting for lab results.

2.    Definitive Antibiotics: Adjust antibiotics based on lab results to target the specific germ.

3.    Duration of Therapy: Take antibiotics for 2 to 6 weeks, depending on infection severity and response to treatment.

Antiviral or Antifungal Therapy:

1.    Antiviral Agents: Take antiviral drugs for viral arthritis like hepatitis C, as per the doctor's recommendation.

2.    Antifungal Agents: Treat fungal arthritis with antifungal medications, either by mouth or intravenously, based on the specific fungus and its susceptibility.

Joint Drainage:

1.    Arthrocentesis: Drain fluid from swollen joints to relieve pain and improve antibiotic delivery.

2.    Surgical Drainage: In severe cases, surgery might be needed to clean out infected joints.

Pain Management:

1.    NSAIDs: Use NSAIDs like ibuprofen for pain and swelling, but be cautious if you have kidney issues or stomach ulcers.

2.    Analgesics: Take acetaminophen for pain relief if NSAIDs aren't suitable for you.

A weekly box of medication.

Physical Therapy:

1.    Range-of-Motion Exercises: Start gentle exercises to improve joint movement once the infection is controlled.

2.    Muscle Strengthening: Build up muscles around the affected joint to improve stability and function under the guidance of a physical therapist.

 Follow-up and Monitoring:

Clinical Assessment:

1.    Regular visits with healthcare providers help monitor symptoms and treatment progress.

2.    Rheumatologists or infectious disease specialists may be involved for specialized care.

Laboratory Monitoring:

1.    Tracking inflammatory markers like CRP and ESR helps evaluate treatment response and detect complications.

Prevention of Complications:

1.    Preventing Joint Damage: Early treatment and proper management reduce the risk of permanent joint damage.

2.    Avoiding Systemic Complications: Timely treatment lowers the chance of infections spreading to other parts of the body.


General Hygiene Practices:

1.    Hand Hygiene: Wash hands often to prevent infection spread.

2.    Respiratory Hygiene: Cover mouth and nose when coughing or sneezing.

3.    Wound Care: Keep wounds clean and covered to prevent infections.


1.    Routine Vaccinations: Stay up-to-date with recommended vaccines to prevent infections.

2.    High-Risk Populations: High-risk groups should get vaccinated to lower infection risks.

Prompt Treatment of Infections:

1.    Early Diagnosis: Catch and treat infections early to prevent complications.

2.    Antimicrobial Therapy: Take prescribed antibiotics as directed to stop infections from spreading.

hygiene washing hands

Infection Control Practices:

Healthcare Settings:

1.    Follow hand hygiene, cleaning, and protective gear protocols to prevent infections in hospitals.

2.    Standard precautions help reduce the spread of germs in medical settings.

Community Settings:

1.    Practice safe food handling, safe sex, and avoid risky behaviors like intravenous drug use.

2.    Community awareness helps stop infections from spreading outside healthcare settings.

Joint Protection:

1.    Prevent joint injuries with safety measures like wearing protective gear during sports.

2.    Antibiotics might be given before dental work or joint surgeries to prevent infections.

Lifestyle Modifications:

1.    Stay healthy with balanced diet, exercise, sleep, and stress management to support the immune system.

2.    Quit smoking to lower the risk of infections and inflammation in joints.

Surveillance and Monitoring:

1.    Keep an eye on high-risk groups like those with autoimmune conditions or immunosuppression.

2.    Public health programs track and manage infectious diseases to prevent outbreaks and complications.


Infectious arthritis, stemming from various pathogens, demands early recognition and tailored treatment to avert joint damage and complications. Identifying predisposing factors and implementing preventive measures can curb its incidence.

Recognizing Symptoms: Understanding infectious arthritis symptoms, ranging from joint pain to systemic manifestations, aids prompt diagnosis and management, averting long-term consequences.

Diagnostic Precision: Accurate diagnosis through clinical evaluation, lab tests, and imaging is pivotal. Differential diagnosis ensures distinguishing it from similar conditions, promoting targeted treatment.

Comprehensive Treatment: The treatment spectrum, including antimicrobial therapy, drainage, pain management, and physical therapy, ensures holistic care. Timely intervention mitigates complications and preserves joint function.

Collaborative Care: Interdisciplinary collaboration among healthcare providers ensures nuanced management, tailored to individual needs. A comprehensive approach maximizes outcomes and patient well-being.

I hope this article has helped you. Please subscribe to my website and I will keep you updated on new blogs.  Also if you need to know anything about arthritis, please go to my contact page and leave a message, and I will get back to you.

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I am not a medical professional, and this blog is for information only. If you have any worries, you should consult your doctor.

I hope this blog has helped.

Linda Rook

Linda is now retired and has suffered from Osteoarthritis for about 40+ years.  She struggled with her weight until she found the correct one that also helped with her arthritic pain.  Linda was in terrible pain until the physician thought her right hip needed replacement. 

Now Linda has an artificial right hip, which has left her with the left leg shorter than the right.  Therefore, her spine is now wonky, and has arthritis of the lower back, also it seems to be going all over the body, her pain is now in the knees, elbow, wrist, fingers and both hips.

Linda now spends her days writing information to help others with the same conditions, so they do not suffer like Linda.

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