Basics
Description
- Bacteria can be introduced into a joint by:
- Hematogenous spread (most common)
- Invasive procedures
- Contiguous infection (e.g., osteomyelitis, cellulitis)
- Direct inoculation such as plant thorns or nails
- Acute inflammatory process results in migration of WBCs into joint.
- Synovial hyperplasia, cartilage damage, and formation of a purulent effusion
- Irreversible loss of function in up to 50%
- Mortality rate reported as high as 11%
- Hip infections are most common:
- Often in patients with otitis media, upper respiratory tract infections or history of femoral venipuncture
- Complications of septic arthritis (SA) of hip in children: Avascular necrosis, epiphyseal separation, pathologic dislocation, and arthritis
- 50% occur in children <3 yr old.
- Infants present with irritability, fever, and loss of appetite.
- Older children present with fever, and a limp or refusal to bear weight or use joint.
Etiology
- Risk factors:
- Old age, infancy
- Rheumatoid arthritis and degenerative joint disease
- Intravenous drug user (IVDU), endocarditis
- Females (gonococcal [GC] infection)
- Immunosuppression (AIDS, diabetes, chemotherapy, steroid therapy)
- Repeated joint injections, pre-existing joint diseases, trauma, or prosthesis
- Skin infection, cutaneous ulcers
- No bacterial pathogen is identified in 10-20%.
- Most common organisms:
- Staphylococcus aureus in adults, hip infections (80%), and patients with rheumatoid arthritis or diabetes
- Multidrug-resistant S. aureus (MRSA) has been noted in some studies to be the most common organism in community-onset adult SA.
- Neisseria gonorrhoeae most common in young, healthy, sexually active patients (incidence has decreased over the past decades due to a decrease in the incidence of mucosal GC infections)
- Other pathogens: Group A β-hemolytic and group B, C, and G streptococci:
- Gram-negative rods (e.g., Pseudomonas aeruginosa, Escherichia. coli) in 10% of cases
- Neisseria meningitides (12% of patients with meningococcal meningitis)
- Common in old age, infancy, immunosuppression, and IVDU (Pseudomonas)
- Anaerobes: Diabetes, prosthetic joints
- Mycobacterial and fungal causes: Atypical (e.g. in advanced HIV); more indolent course
Diagnosis
Signs and Symptoms
- Presents abruptly as a single painful, swollen, warm, tender joint
- Common findings include:
- Fever
- A separate source of infection (e.g., skin)
- Extremely painful joint motion in all planes
- A joint effusion (less evident in sacroiliac, hip, and shoulder)
- Any joint can be involved:
- Typically a single joint is involved.
- Most commonly knee, then hip, shoulder, and ankle
- Commonly seen in IVDUs: Sacroiliac costochondral and sternoclavicular joints:
- Vertebral involvement such as lumbar facets possible
- Human and animal bites, plant thorns, local steroid therapy, and trauma may lead to infection in atypical locations.
- Polyarticular involvement in 10-20%:
- Mostly with rheumatoid arthritis; delay in diagnosis from low suspicion and more subtle presentations (fever in only 50%)
- Patients with sepsis
- GC SA features:
- Develops in 1-3% of untreated gonorrhea and in 42-85% of disseminated GC infection:
- Typically monoarticular but commonly polyarticular
- Migratory polyarthralgia, tenosynovitis (present in 20% of patients with arthritis), and dermatitis:
- Involves small joints (e.g., fingers, wrist, elbow, ankle)
- Signs of urethral or vaginal GC infection may be present.
- Painless maculopapular lesions on trunk, arms, legs, and around affected joint
Essential Workup
Arthrocentesis
- Perform joint aspiration in any suspected case.
- Send fluid for protein and glucose, cell count, Gram stain, and culture.
- Typical SA findings:
- A turbid, purulent, or serosanguineous fluid
- A leukocytosis (50,000-150,000/mm3) with a polymorphonuclear predominance (>75%)
- Often a decreased glucose and elevated protein level
- Appearance of crystals does not rule out SA.
- Use special stain or culture media when indicated (e.g., GC, anaerobes, fungus, mycobacterium)
- Intra-articular lidocaine reduces the sensitivity of subsequent cultures; immediate emptying of aspirated sample into a blood culture flask increases the yield.
- In non-GC SA, Gram stain and culture are positive in 50% and 90% of cases, respectively:
- Drops to nearly 10% and 50% in GC SA, respectively
- Real-time PCR can detect bacterial pathogen DNA in many culture-negative aspirates.
- Fluoroscopic, sonographic, or CT guidance can be used in technically difficult aspirations.
- CT scan and MRI may aid in the diagnosis for joints such as the sacroiliac joint.
- Arthrocentesis is contraindicated whenever there is an underlying joint prosthesis or an overlying skin infection:
- If cellulitis present, use an alternate approach through normal skin.
Diagnosis Tests & Interpretation
Lab
- Nonspecific serum leukocytosis (more common in children), left shift, and C-reactive protein (CRP) and ESR elevation are usually present.
- Procalcitonin can be a helpful aid to rule in rather than rule out SA
- UA and culture can reveal a urologic source for the pathogen.
- Blood cultures may be useful: Positive in 50-70% of non-GC SA.
- Culture any potential focus of infection (pharynx, urine, cervix, or anus), particularly when suspecting GC.
Imaging
- Plain radiographs to identify:
- Effusion
- Baseline status of the joint
- Contiguous osteomyelitis
- Concurrent rheumatologic diseases
- Fractures or foreign body
- Joint loosening (a late nonspecific sign)
- US, CT, and MRI are more sensitive:
- US may be used to guide aspiration of some joints (e.g., hip) and to detect joint effusions.
- Scintigraphic techniques are sensitive and specific in diagnosis of SA. However, they are often not available through ED.
- Other tests:
- Bacterial DNA amplification techniques in rapid detection and identification of organisms
Differential Diagnosis
- Viral arthritis
- Rheumatoid arthritis
- Gout or pseudogout
- HIV-associated arthritis
- Reactive arthritis
- Lyme disease
- Osteomyelitis
- Endocarditis
- Septic bursitis
- Trauma
- In children:
- Juvenile idiopathic arthritis
- Slipped capital femoral epiphysis
- Legg-Calv ©-Perthes disease
- Metaphyseal osteomyelitis
- Transient synovitis
- Because of vaccine, Haemophilus influenzae is no longer the most common agent.
- S. aureus is most common.
- Group B streptococcus, enterobacteria, and gram-negative rods in the newborn
Treatment
Pre-Hospital
No specific considerations
Initial Stabilization/Therapy
- Patient may be septic and require resuscitation.
- If patient is toxic, do not delay antibiotics for aspiration results.
Ed Treatment/Procedures
- Promptly aspirate joint fluid.
- Obtain cultures.
- Start empiric antibiotics based on Gram stain (if available) and age group or risk factors-consider staphylococcal, streptococcal, and gram-negative coverage; and MRSA in the appropriate setting. Recommended duration of treatment is 2-4 wk. Intra-articular antibiotics are contraindicated.
- No risk factors for atypical organisms:
- Use Flucloxacillin or equivalent 2 g QDS IV. Local policy may be to add gentamicin IV.
- If penicillin allergic, clindamycin 450-600 mg QDS IV or 2nd or 3rd generation cephalosporin IV.
- High risk of gram-negative sepsis (elderly, frail, recurrent UTI, and recent abdominal surgery):
- 2nd or 3rd generation cephalosporin for example, cefuroxime 1.5 g TDS IV. Local policy may be to add flucloxacillin IV to 3rd generation cephalosporin.
- Gram stain may influence antibiotic choice.
- MRSA risk (known MRSA, recent inpatient, nursing home resident, leg ulcers or catheters, or other risk factors determined locally):
- Vancomycin IV + 2nd or 3rd generation cephalosporin IV
- Suspected gonococcus or meningococcus:
- Ceftriaxone IV or similar
- Dependent on local policy or resistance
- IVDUs: Discuss with microbiologist
- ICU patients, known colonization of other organs (e.g., cystic fibrosis): Discuss with microbiologist
- Early orthopedic consultation to evaluate eligibility for surgical drainage
- Pain control: Narcotics and moderately flexed splinting
- Immunologic therapies are experimental.
- Prosthesis: Some may try to preserve the limb unless it is loose on plain films.
- Patients should be at rest with joint maintained in optimal position to prevent damage.
Medication
- Cefazolin: 1-2 g IV q6h
- Ceftazidime: 1-2 g IV q8h
- Cefotaxime: 2 g IV q8h; peds: 50 mg/kg q12h
- Ceftriaxone:2 g IV QD; peds: 50 mg/kg
- Ciprofloxacin: 400 mg IV q12h
- Flucloxacillin: 2 g QD IV
- Gentamicin: 2-5 mg/kg IV load
- Nafcillin: 2 g IV q4h; peds: 25 mg/kg q6h
- Tobramycin: 1 mg/kg IV q8h; peds: 2.5 mg/kg q8h
- Vancomycin: 1 g IV q12h; peds: 10 mg/kg q6h
- Open surgical drainage is the method of choice in pediatric hip SA.
- Cover H. influenzae type B if prior immunization cannot be established.
Follow-Up
Disposition
Admission Criteria
- All patients with suspected SA should be admitted until SA is ruled out.
- May undergo drainage of joint, as indicated, by serial aspirations, arthroscopy, or arthrotomy
Discharge Criteria
Cases where suspected SA has been adequately ruled out
Pearls and Pitfalls
- CRP and ESR can be used to follow up response to treatment
- It can be difficult to distinguish SA from toxic synovitis or crystal arthropathy; have a low threshold for arthrocentesis.
Additional Reading
- Carpenter CR, Schuur JD, Everett WW, et al. Evidence-based diagnostics: Adult septic arthritis. Acad Emerg Med. 2011;18:781-796.
- Coakley G, Mathews C, Field M, et al. BSR & BHPR, BOA, RCGP and BSAC guidelines for management of the hot swollen joint in adults. Rheumatology. 2006;45:1039-1041.
- Mathews CJ, Weston VC, Jones A, et al. Bacterial septic arthritis in adults. Lancet. 2010;375:846-855.
- Rosey AL, Abachin E, Quesnes G, et al. Development of a broad-range 16S rDNA real-time PCR for the diagnosis of septic arthritis in children. J Microbiol Methods. 2007;68:88-93.
- Shen CJ, Wu MS, Lin KH, et al. The use of procalcitonin in the diagnosis of bone and joint infection: A systemic review and meta-analysis. Eur J Clin Microbiol Infect Dis. 2013;32(6):807-814.
- Weisfelt M, van de Beek D, Spanjaard L, et al. Arthritis in adults with community-acquired bacterial meningitis: A prospective cohort study. BMC Infect Dis. 2006;6:64.
Codes
ICD9
- 711.00 Pyogenic arthritis, site unspecified
- 711.05 Pyogenic arthritis, pelvic region and thigh
- 711.45 Arthropathy associated with other bacterial diseases, pelvic region and thigh
ICD10
- M00.9 Pyogenic arthritis, unspecified
- M00.052 Staphylococcal arthritis, left hip
- M00.059 Staphylococcal arthritis, unspecified hip
- M00.051 Staphylococcal arthritis, right hip
- M00.05 Staphylococcal arthritis, hip
- M00.859 Arthritis due to other bacteria, unspecified hip
SNOMED
- 396234004 Infective arthritis (disorder)
- 372941008 Pyogenic arthritis of hip