Bacteria, viruses, or fungi may spread through the bloodstream or from a nearby infection into a joint, causing infection.
Pain, swelling, and fever usually develop within hours or a couple of days.
Joint fluid is withdrawn with a needle and tested.
Antibiotics are begun immediately.
There are two types of infectious arthritis:
Acute infectious arthritis
Acute infectious arthritis that is caused by bacteria begins quickly. Most cases of infectious arthritis are acute. Acute infectious arthritis can affect healthy people as well as people who have risk factors Acute infectious arthritis Infectious arthritis is infection in the fluid and tissues of a joint usually caused by bacteria but occasionally by viruses or fungi. Bacteria, viruses, or fungi may spread through the bloodstream... read more . Cartilage within the joint, which is essential for normal joint function, can be destroyed or damaged within hours or days.
Sometimes, arthritis develops in people who have infections that do not involve the bones or joints, such as infections of the genital organs or digestive organs. This type of arthritis is a reaction to that infection and so is called reactive arthritis Reactive Arthritis Reactive arthritis (previously called Reiter syndrome) is a spondyloarthritis causing inflammation of the joints and tendon attachments at the joints, often related to an infection. Joint pain... read more . In reactive arthritis, the joint is inflamed but not actually infected.
Chronic infectious arthritis
Chronic infectious arthritis begins gradually over several weeks. Very few cases of infectious arthritis are chronic. Chronic infectious arthritis most often affects people who have risk factors Chronic infectious arthritis Infectious arthritis is infection in the fluid and tissues of a joint usually caused by bacteria but occasionally by viruses or fungi. Bacteria, viruses, or fungi may spread through the bloodstream... read more .
The joints most commonly infected are the knee, shoulder, wrist, hip, elbow, and the joints of the fingers. Most bacterial, fungal, and mycobacterial infections affect only one joint or, occasionally, several joints. For example, the bacteria that cause Lyme disease most often infect knee joints. Gonococcal bacteria (gonococci), which cause gonorrhea Gonorrhea Gonorrhea is a sexually transmitted infection caused by the bacteria Neisseria gonorrhoeae, which infect the lining of the urethra, cervix, rectum, and throat or the membranes that cover... read more , viruses (such as hepatitis), and occasionally some other bacteria can infect a few or many joints at the same time.
Causes of Infectious Arthritis
Organisms that cause infection, mainly bacteria, usually spread to the joint from a nearby infection (such as osteomyelitis Osteomyelitis Osteomyelitis is a bone infection usually caused by bacteria, mycobacteria, or fungi. Bacteria, mycobacteria, or fungi can infect bones by spreading through the bloodstream or, more often, by... read more or an infected wound) or through the bloodstream. A joint can be infected directly if it is contaminated during surgery or by an injection or an injury (such as a bite wound from a person Human Bites Because human teeth are not particularly sharp, most human bites cause a bruise and only a shallow tear ( laceration), if any. Exceptions are on fleshy appendages, such as the ears, nose, and... read more or a bite from a dog, cat, or rat Animal Bites Most animal bites in the United States are from dogs and cats. Wounds should be cleaned and cared for as soon as possible. (See also Introduction to Bites and Stings.) Although any animal may... read more ).
Acute infectious arthritis
Acute infectious arthritis is usually caused by bacteria and viruses.
Different bacteria can infect a joint, but the bacteria most likely to cause acute infectious arthritis depend on a person’s age:
Newborns: Group B streptococci Streptococcal Infections Streptococcal infections are caused by any one of several species of Streptococcus. These gram-positive, sphere-shaped (coccal) bacteria (see figure How Bacteria Shape Up) cause many... read more , Escherichia coli Escherichia coli Infections Escherichia coli (E. coli) are a group of gram-negative bacteria that normally reside in the intestine of healthy people, but some strains can cause infection in the digestive... read more (E. coli and other bacteria known as gram-negative bacilli Overview of Gram-Negative Bacteria Bacteria are classified by how they appear under the microscope and by other features. Gram-negative bacteria are classified by the color they turn after a chemical process called Gram staining... read more ), and Staphylococcus aureus Staphylococcus aureus Infections Staphylococcus aureus is the most dangerous of all of the many common staphylococcal bacteria. These gram-positive, sphere-shaped (coccal) bacteria (see figure How Bacteria Shape Up)... read more
Infants and young children: Staphylococcus aureus, streptococci Streptococcal Infections Streptococcal infections are caused by any one of several species of Streptococcus. These gram-positive, sphere-shaped (coccal) bacteria (see figure How Bacteria Shape Up) cause many... read more , gram-negative bacilli, and Kingella kingae
Older children and adults: Staphylococcus aureus, streptococci, and gonococci Gonorrhea Gonorrhea is a sexually transmitted infection caused by the bacteria Neisseria gonorrhoeae, which infect the lining of the urethra, cervix, rectum, and throat or the membranes that cover... read more
Spirochetes (a type of bacteria), such as those that cause Lyme disease Lyme Disease Lyme disease is a tick-transmitted infection caused by Borrelia species, primarily by Borrelia burgdorferi and sometimes by Borrelia mayonii in the United States. These... read more and syphilis Syphilis Syphilis is a sexually transmitted infection caused by the bacteria Treponema pallidum. Syphilis can occur in three stages of symptoms, separated by periods of apparent good health. It... read more , can infect joints.
Viruses, such as HIV Hepatitis B, Acute Acute hepatitis B is inflammation of the liver that is caused by the hepatitis B virus and that lasts from a few weeks up to 6 months. Hepatitis B is spread through contact with blood or other... read more , parvoviruses, and those that cause rubella Rubella Rubella is a contagious viral infection that typically causes mild symptoms, such as joint pain and a rash, but can cause severe birth defects if the mother becomes infected with rubella during... read more , mumps Mumps Mumps is a contagious viral infection that causes painful enlargement of the salivary glands. The infection may also affect the testes, brain, and pancreas, especially in adults. Mumps is caused... read more , and hepatitis B Overview of Hepatitis Hepatitis is inflammation of the liver. (See also Overview of Acute Viral Hepatitis and Overview of Chronic Hepatitis.) Hepatitis is common throughout the world. Hepatitis can be Acute (short-lived) read more and hepatitis C Hepatitis C, Acute Acute hepatitis C is inflammation of the liver that is caused by the hepatitis C virus and that lasts from a few weeks up to 6 months. Hepatitis C is spread through contact with blood or other... read more , can infect joints in people of any age.
There are many risk factors for infectious arthritis. Most children who develop infectious arthritis do not have identified risk factors.
Risk factors for acute infectious arthritis include
A past history of joint infection
Use of needles to inject drugs
Certain chronic illnesses (such as diabetes Diabetes Mellitus (DM) Diabetes mellitus is a disorder in which the body does not produce enough or respond normally to insulin, causing blood sugar (glucose) levels to be abnormally high. Urination and thirst are... read more , lupus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic autoimmune inflammatory connective tissue disorder that can involve joints, kidneys, skin, mucous membranes, and blood vessel walls. Problems in the... read more , and chronic lung or liver disorders)
Behaviors that increase risk of sexually transmitted infections Overview of Sexually Transmitted Infections (STIs) Sexually transmitted (venereal) diseases are infections that are typically, but not exclusively, passed from person to person through sexual contact. Sexually transmitted infections may be caused... read more (such as sex with multiple partners and without use of condoms)
Disorders that cause ongoing joint damage (including rheumatoid arthritis Rheumatoid Arthritis (RA) Rheumatoid arthritis is an inflammatory arthritis in which joints, usually including those of the hands and feet, are inflamed, resulting in swelling, pain, and often destruction of joints.... read more , osteoarthritis Osteoarthritis (OA) Osteoarthritis is a chronic disorder that causes damage to the cartilage and surrounding tissues and is characterized by pain, stiffness, and loss of function. Arthritis due to damage of joint... read more , and arthritis caused by injury)
For example, bacteria may become deposited in one or more joints in a person who has pneumonia Overview of Pneumonia Pneumonia is an infection of the small air sacs of the lungs (alveoli) and the tissues around them. Pneumonia is one of the most common causes of death worldwide. Often, pneumonia is the final... read more (a lung infection) or sepsis Sepsis and Septic Shock Sepsis is a serious bodywide response to bacteremia or another infection plus malfunction or failure of an essential system in the body. Septic shock is life-threatening low blood pressure ... read more (a bloodstream infection), resulting in infectious arthritis.
Acute infectious arthritis may occur in children who have no risk factors. About 50% of children with joint infection are under 3 years of age. However, routine childhood vaccination Childhood Vaccination Schedule Most doctors follow the vaccination schedule recommended by the Centers for Disease Control and Prevention (CDC—see the schedule for infants and children and the schedule for older children... read more for Haemophilus influenzae Haemophilus influenzae Type b Vaccine The Haemophilus influenzae type b (Hib) vaccine helps protect against bacterial infections due to Hib, such as pneumonia and meningitis. These infections may be serious in children. Use... read more and Streptococcus pneumoniae Pneumococcal Vaccine Pneumococcal vaccines help protect against bacterial infections caused by Streptococcus pneumoniae (pneumococci). Pneumococcal infections include ear infections, sinusitis, pneumonia... read more is lowering the incidence in this age group.
Chronic infectious arthritis
Chronic infectious arthritis is usually caused by Mycobacterium tuberculosis (the main cause of tuberculosis Tuberculosis (TB) Tuberculosis is a chronic contagious infection caused by the airborne bacteria Mycobacterium tuberculosis. It usually affects the lungs, but almost any organ can be involved. Tuberculosis... read more ), fungi, or bacteria.
Risk factors for chronic infectious arthritis include
A suppressed immune system Overview of the Immune System The immune system is designed to defend the body against foreign or dangerous invaders. Such invaders include Microorganisms (commonly called germs, such as bacteria, viruses, and fungi) Parasites... read more (due to cancer or use of drugs that suppress the immune system Secondary immunodeficiency disorders )
Did You Know...
Symptoms of Infectious Arthritis
In acute infectious arthritis, symptoms usually begin over hours to a few days. The infected joint usually becomes severely painful and sometimes red and warm. Moving or touching it is very painful. Fluid collects in the infected joint, causing it to swell and stiffen. Symptoms sometimes also include fever and chills. Very rarely, septic shock Sepsis and Septic Shock Sepsis is a serious bodywide response to bacteremia or another infection plus malfunction or failure of an essential system in the body. Septic shock is life-threatening low blood pressure ... read more develops.
Gonococcal arthritis usually causes milder symptoms. People typically have a fever for 5 to 7 days. People may have skin blisters, bumps, sores, or rashes, or sores on the mouth or genitals and on the trunk, hands, or legs. Pain may move from one joint to another before a joint becomes swollen and tender. Tendons may become inflamed.
Infants and children too young to talk tend not to move the infected joint, are irritable, may refuse to eat, and may have a fever, or may have no fever. Young children with knee or hip infections may refuse to walk.
In chronic infectious arthritis, symptoms are usually gradual swelling, mild warmth, minimal or no redness of the joint area, and aching pain that may be mild and less severe than in acute infectious arthritis. Usually, a single joint is involved.
People may have other symptoms depending on the cause of infectious arthritis, such as symptoms of Lyme disease, or swollen lymph nodes if the cause is an infected bite wound.
Diagnosis of Infectious Arthritis
Analysis and culture of joint fluid
Sometimes sputum, spinal fluid, and urine tests
Sometimes x-rays, magnetic resonance imaging (MRI), or ultrasonography
Doctors typically suspect the diagnosis of infectious arthritis in people who have severe or unexplained arthritis and in people who have other combinations of symptoms that are known to occur in people who have infectious arthritis.
Usually, a sample of joint fluid is removed with a needle (called joint aspiration Joint aspiration (arthrocentesis) A doctor can often diagnose a musculoskeletal disorder based on the history and the results of a physical examination. Laboratory tests, imaging tests, or other diagnostic procedures are sometimes... read more , or arthrocentesis) as soon as possible. It is examined for an increased number of white blood cells and tested for bacteria and other organisms. The laboratory can usually grow and identify the infecting bacteria from the joint fluid (called a culture), unless the person has recently taken antibiotics. However, the bacteria that cause gonorrhea, Lyme disease, and syphilis are difficult to recover from joint fluid. If bacteria do grow in culture, the laboratory then tests which antibiotics would be effective.
A doctor usually does blood tests because bacteria causing joint infections often appear in the bloodstream. Sputum, spinal fluid, and urine may also be tested for bacteria to help determine the source of infection and determine whether the infection is anywhere else.
If doctors suspect the infectious arthritis is caused by gonococci Gonorrhea Gonorrhea is a sexually transmitted infection caused by the bacteria Neisseria gonorrhoeae, which infect the lining of the urethra, cervix, rectum, and throat or the membranes that cover... read more , samples are also taken from the urethra, cervix, rectum, and throat. Tests for chlamydial infection Chlamydial and Other Nongonococcal Infections Chlamydial infections include sexually transmitted infections of the urethra, cervix, and rectum that are caused by the bacteria Chlamydia trachomatis. These bacteria can also infect... read more of the genitals (another sexually transmitted infection) are also done because many people who have gonorrhea also have a chlamydial infection.
To make the bacteria easier to detect and identify, doctors may analyze the joint fluid using the polymerase chain reaction technique (a type of nucleic acid amplification test [NAAT]) to detect the DNA of gonococci and mycobacteria.
Doctors may take x-rays X-rays A doctor can often diagnose a musculoskeletal disorder based on the history and the results of a physical examination. Laboratory tests, imaging tests, or other diagnostic procedures are sometimes... read more of the affected joint to rule out other conditions. Doctors may do magnetic resonance imaging Computed tomography (CT) and magnetic resonance imaging (MRI) A doctor can often diagnose a musculoskeletal disorder based on the history and the results of a physical examination. Laboratory tests, imaging tests, or other diagnostic procedures are sometimes... read more (MRI) if the joint cannot be easily examined or aspirated. MRI or ultrasonography Ultrasonography Ultrasonography uses high-frequency sound (ultrasound) waves to produce images of internal organs and other tissues. A device called a transducer converts electrical current into sound waves... read more is also done to identify accumulations of fluid or collections of pus (abscesses).
Prognosis for Infectious Arthritis
Infectious arthritis that is caused by nongonococcal bacteria can permanently destroy joint cartilage within hours or days.
Infectious arthritis that is caused by gonococcal bacteria does not usually damage joints permanently.
People with rheumatoid arthritis usually do not regain total use of the infected joint, and the risk of death is increased.
Treatment of Infectious Arthritis
Antibiotics or antifungal drugs
Removal of pus
Splinting of the joint, followed by physical therapy
Nonsteroidal anti-inflammatory drugs Nonsteroidal Anti-Inflammatory Drugs Pain relievers (analgesics) are the main drugs used to treat pain. Doctors choose a pain reliever based on the type and duration of pain and on the drug's likely benefits and risks. Most pain... read more (NSAIDs) and sometimes other analgesics are used to help reduce pain, inflammation, and fever.
It is important to start antibiotics as soon as an infection is suspected, even before the laboratory has identified the infecting organism. Antibiotics that kill the bacteria that are most likely causing the infection are given until the infecting organism is identified, usually within 48 hours of testing the joint fluid. Antibiotics are given by vein (intravenously) at first to ensure that enough of the drug reaches the infected joint.
If the antibiotics are effective against the infecting bacteria, some improvement usually occurs within 48 hours. As soon as the doctor receives the laboratory results, the antibiotic may be changed depending on the sensitivity of the particular bacteria to specific antibiotics. Intravenous antibiotics are continued for 2 to 4 weeks. Then, antibiotics are given by mouth at high doses for another 2 to 6 weeks.
An infection that lasts a long time and that does not go away after use of conventional antibiotics may be caused by mycobacteria or fungi. Infections caused by fungi are treated with antifungal drugs. Infections caused by mycobacteria are treated with a combination of antibiotics. Infections caused by fungi and mycobacteria require long-term treatment.
Infections caused by viruses usually get better without antibiotic treatment.
Removal of pus
The doctor often removes pus with a needle (aspiration) to prevent its accumulation because accumulated pus may damage a joint and may be more difficult to cure with antibiotics. If drainage with a needle is difficult (as with a hip joint) or unsuccessful, arthroscopy Arthroscopy A doctor can often diagnose a musculoskeletal disorder based on the history and the results of a physical examination. Laboratory tests, imaging tests, or other diagnostic procedures are sometimes... read more (a procedure using a small scope to view the inside of the joint directly) or surgery may be needed to drain the joint. Aspiration is often done more than once. Sometimes a tube is left in place to drain the pus.
Splinting and physical therapy
Splinting of the joint (to keep it from moving) is done for the first few days of the infection to help ease pain, but physical therapy Physical Therapy (PT) Physical therapy, a component of rehabilitation, involves exercising and manipulating the body with an emphasis on the back, upper arms, and legs. It can improve joint and muscle function, helping... read more is then started to strengthen muscles and prevent stiffness and permanent loss of function.
The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
Arthritis Foundation: Comprehensive information on various types of arthritis, including infectious arthritis, and information regarding living with arthritis