AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Nongonococcal infectious arthritis is an acute or subacute illness with potentially significant morbidity and mortality. Bacteria, mycobacteria, and fungi can cause the disease. Both healthy individuals and individuals with predisposing conditions can be infected. Nongonococcal infectious arthritis is typically a monoarticular disease, but, in approximately 10% of patients, it affects multiple joints. Without treatment, the condition results in joint destruction.

Pathophysiology

Infectious arthritis ensues when foreign organisms invade the synovium or joint space. These organisms invade the joint via (1) hematogenous dissemination from a distant site; (2) periarticular infection, such as osteomyelitis or adjacent soft-tissue infection; or (3) direct introduction through penetrating trauma or procedural intervention, such as arthrocentesis or surgical repair.

Frequency

United States

The yearly incidence of bacterial arthritis varies from 2-10 cases per 100,000 persons in the general population to 30-70 cases per 100,000 persons in patients with rheumatoid arthritis.

Mortality/Morbidity

• Mortality occurs in 10-15% of cases.
• Joint destruction occurs in 25-50% of cases.

Race

• No inherent racial predilections for infectious arthritis are recognized.

Sex

• Sex is not an independent risk factor to predispose individuals to infectious arthritis.

Age

• Age older than 80 years has been shown in some studies to be an independent risk factor for susceptibility to bacterial arthritis.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

• The clinical course of bacterial arthritis is typically acute in onset.
• • Patients with joint prostheses are the exception. These patients' symptoms may persist for weeks or months before a diagnosis is made.
  • Individuals with mycobacterial or fungal arthritis also tend to have a much more indolent or subacute prodrome before the diagnosis is considered.
  • The sternoclavicular and sacroiliac joints are preferentially involved in patients who abuse parenteral drugs.
• Joint pain, swelling, erythema, and loss of motion are common presenting symptoms.
• • The most commonly affected joint in persons with bacterial arthritis is the knee.
  • The shoulder, hip, elbow, and wrist joints are infected less frequently.
• Approximately 10% of individuals with bacterial arthritis have infection in multiple joints, particularly in the presence of a preexisting destructive joint disease (eg, rheumatoid arthritis) or compromising medical conditions (eg, diabetes, glucocorticoid therapy).

Physical

• During the first 24 hours of hospitalization, 78% of patients with nongonococcal bacterial arthritis exhibit fever; however, the fever rarely exceeds 39°C (102.2°F).
• The patient may have decreased range of motion in the joint.
• Swelling, tenderness to palpation, erythema, warmth to touch, and pain upon movement of the affected joint are common physical examination findings.

Causes

• Risk factors
• • The presence of a preexisting, chronic, inflammatory, destructive arthritis, especially rheumatoid arthritis, is correlated with infectious arthritis. The recent introduction of anti–tumor necrosis factor (TNF) agents in the treatment of inflammatory arthritis may additionally predispose this population to infectious arthritis.
  • A person undergoing immunosuppressive therapy, such as with corticosteroids or cytotoxic agents, is more likely to become infected.
  • A person who has a prosthetic joint has greater risk of infection.
  • Elderly individuals are particularly at risk for infectious arthritis.
  • Comorbid nonarticular conditions, such as diabetes mellitus, immunodeficiency diseases, cancer, or intravenous drug abuse, also increase the risk of infectious arthritis.
• Bacteria
• • Gram-positive cocci, especially Staphylococcus aureus, are the predominant etiologic agents. Streptococcal species are also common, especially group A streptococci.
  • If a prosthetic joint was implanted within the preceding 6 months, Staphylococcus epidermidis and S aureus are major pathogens.
  • Gram-negative bacilli are more common in elderly patients with chronic medical conditions.
  • Pseudomonas aeruginosa and methicillin-resistant S aureus are more prevalent in the infectious arthritis that affects individuals who abuse intravenous drugs.
  • Salmonella species exhibit a predilection for individuals with systemic lupus erythematosus.
  • Consider Pasteurella multocida subsequent to a cat bite or Eikenella corrodens after a human bite.
• Mycobacteria
• • In addition to the common pathogen Mycobacterium tuberculosis, nontuberculous species, such as Mycobacterium kansasii, may spread from a pulmonary focus and infect a joint.
  • Mycobacterium marinum should be considered in individuals exposed to aquatic or marine environments.
• Fungi
• • Candida organisms, including Candida albicans and Candida parapsilosis, are causative in debilitated hospitalized patients or in patients on long-term antibacterial therapy.
  • Sporothrix schenckii may infect the hand or wrist joints of a person frequently exposed to moist soil, rose thorns, or the outdoors.

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Synovial fluid tests
• • The synovial fluid cell count is generally higher than 50,000/µL, with a predominance of neutrophils greater than 90% in persons with acute bacterial arthritis.
  • Results of a Gram stain of synovial fluid are positive in approximately 75% of patients with staphylococcal infections; however, results are positive in only 50% of patients with gram-negative infections.
  • A microscopic examination of synovial fluid for monosodium urate crystals and calcium pyrophosphate crystals is performed to exclude crystal-induced arthritis (eg, gout, pseudogout); however, recognizing the possibility of infectious arthritis and crystal-induced arthritis coexisting in a single joint is also important, although this is reportedly very uncommon.
  • A culture of synovial fluid should be performed for aerobic and anaerobic organisms. Inoculation of blood culture bottles is more sensitive than culture on solid medium, especially in patients pretreated with antibiotics.
  • A biopsy of synovial tissue for culture and histologic examination is important if mycobacterial or fungal infections are suggested. A culture of synovial fluid is an insensitive diagnostic test in this setting.
• Complete blood cell count
• • Leukocytosis is common in patients with acute bacterial arthritis.
  • Approximately 50% of persons with acute disease exhibit WBC counts greater than 10,000/µL.
• Blood culture: Results are positive in approximately 33-50% of patients with nongonococcal bacterial arthritis.

Imaging Studies

• Radiography
• • Plain radiography findings are generally nonspecific and may reveal only a joint effusion in the early stages of infection.
  • Cartilage destruction and joint space narrowing are late findings and may be difficult to interpret if the patient has a preexisting joint disease.
• CT scanning: This study may help to diagnose sternoclavicular or sacroiliac joint infections.
• MRI: MRI is most useful in assessing the presence of periarticular osteomyelitis as a causative mechanism.
• Radionuclide images
• • Findings from radionuclide studies, such as bone scans, are positive for any inflammatory arthritis and are therefore very nonspecific.
  • These may be useful for diagnosing sternoclavicular or sacroiliac joint infection.

Procedures

• Arthrocentesis with synovial biopsy
• • If indicated, this is the single most important diagnostic procedure for evaluating infectious arthritis.
  • It allows for culture and appropriate microscopic examination of the synovial fluid and tissue.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical Care

• The most important consideration in the treatment of infectious arthritis is the rapid institution of appropriate antimicrobial therapy. Daily joint aspiration must be performed until inflammation subsides.
• Patients with bacterial arthritis must be hospitalized.
• • Intravenous antibiotic therapy is initiated immediately upon admission. If the results of a Gram stain of synovial fluid identify no organism, initiate empiric therapy based on the clinical characteristics of the host.
  • Healthy adults can be treated with antistaphylococcal penicillin or cephalosporin. Patients who reside in communities with a high prevalence of community-acquired methicillin-resistant S aureus should be initially treated with vancomycin pending culture results.
  • Elderly debilitated patients or patients with chronic medical conditions require expanded antimicrobial coverage to cover gram-negative bacteria. This usually requires the addition of a third-generation cephalosporin, an aminoglycoside, or a quinolone.
  • Patients with nosocomial infections in whom pseudomonal species are considered may need an extended-spectrum penicillin such as piperacillin or carbenicillin.
  • Cultural sensitivities, when available, may help identify appropriate modifications to subsequent therapy.
  • Depending on the causative organism, most experts recommend 2-4 weeks of parenteral therapy.
  • Institute daily arthrocentesis of the affected joint until synovial fluid culture results are negative or considerable clinical improvement in the joint is apparent.
• Fungal arthritis is appropriately treated with intravenous amphotericin B plus an oral azole. The recommended duration of therapy is 6-12 weeks, for a total dose of 1-3 g of amphotericin B.
• Mycobacterial arthritis treatment varies depending on the infecting agent.
• • Patients with M tuberculosis infection are treated initially with 4 drugs (rifampin, isoniazid, pyrazinamide, ethambutol [RIPE]) for 2 months; then, depending on the sensitivities, isoniazid and rifampin are continued for a total of 9-12 months.
  • An M marinum infection requires rifampin and ethambutol for 6-12 weeks.

Surgical Care

• Joints that do not respond to antimicrobial therapy and daily arthrocentesis require drainage and debridement, either with arthroscopy or with an open procedure.
• A joint with an infected prosthesis requires removal of the prosthesis and reimplantation after an appropriate course of antimicrobial therapy.

Consultations

• Rheumatologist
• Orthopedic surgeon

Activity

• Encourage either passive or active daily range-of-motion exercises.
• Avoid immobilizing the joint.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Antimicrobial therapy is dictated by the results of a Gram stain and the clinical characteristics of the host. If the Gram stain result is positive for gram-positive cocci, then S aureus and streptococci are the most likely infecting agents. If the patient is a healthy sexually active adult, gonococci and gram-positive cocci are the most likely infecting agents. If the Gram stain result is negative in an elderly or compromised host, an increased prevalence of gram-negative rods is likely. A patient with a prosthetic joint or a patient who has undergone a recent operative procedure is likely to have an increased prevalence of S epidermidis and gram-negative rods.

Drug Category: Antibiotics

Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.

Drug Category: Antitubercular agents

These agents are used when therapy for tuberculous arthritis is indicated.

Drug Category: Antifungals

These agents are used when fungal arthritis, such as candidal arthritis, is documented.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Inpatient Care

• Admit patients for parenteral antibacterial therapy and daily arthrocentesis.
• Perform surgical debridement if no response to medical therapy is observed.

Deterrence/Prevention

• Patients with prosthetic joints require antibacterial prophylaxis before surgical procedures. This prophylaxis is similar to the treatment indicated for endocarditis prophylaxis in patients with valvular heart disease.

Complications

• Irreversible loss of joint function may result if the condition is not treated immediately and for an appropriate duration.

Prognosis

• Morbidity and mortality rates are increased in elderly individuals and individuals with preexisting medical conditions.

Patient Education

• For excellent patient education resources, visit eMedicine's Arthritis Center and Bacterial and Viral Infections Center. Also, see eMedicine's patient education article Knee Pain.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Failure to consider an infectious etiology in monoarticular arthritic flares in the setting of chronic inflammatory polyarthritis

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

• Chambers HF. Community-associated MRSA--resistance and virulence converge. N Engl J Med. Apr 7 2005;352(14):1485-7. [Medline].
• Goldenberg DL, Reed JI. Bacterial arthritis. N Engl J Med. Mar 21 1985;312(12):764-71. [Medline].
• Harrington JT. Mycobacterial and fungal arthritis. Curr Opin Rheumatol. Jul 1998;10(4):335-8. [Medline].
• Kaandorp CJ, Krijnen P, Moens HJ, Habbema JD, van Schaardenburg D. The outcome of bacterial arthritis: a prospective community-based study. Arthritis Rheum. May 1997;40(5):884-92. [Medline].
• Mathews CJ, Kingsley G, Field M, Jones A, Weston VC, Phillips M, et al. Management of septic arthritis: a systematic review. Ann Rheum Dis. Apr 2007;66(4):440-5. [Medline].
• Shirtliff ME, Mader JT. Acute septic arthritis. Clin Microbiol Rev. Oct 2002;15(4):527-44. [Medline].
• Smith JW, Chalupa P, Shabaz Hasan M. Infectious arthritis: clinical features, laboratory findings and treatment. Clin Microbiol Infect. Apr 2006;12(4):309-14. [Medline].
• von Essen R. Culture of joint specimens in bacterial arthritis. Impact of blood culture bottle utilization. Scand J Rheumatol. 1997;26(4):293-300. [Medline].

Article Last Updated: Nov 26, 2007