septic arthritis inflammation of a joint caused by a bacterial infection
TRANSCRIPT
Septic arthritis
Inflammation
of a joint caused by
a bacterial infection
Septic arthritis is also called infectious arthritis
Septic arthritis is diagnosed by identifying
infected joint fluid
Epidemiology
Incidence:
General population 2-5/100,000/yr
Children 5.5 - 12/100,000/yr
RA 28 - 38/100,000/yr
Prosthetic joint 40 - 68/100,000/yr
Monoarticular (<20% more than one joint)
Large joints>small joints
Knee (>50%), ankle, wrist, hip, …
The most common joints to become infected are the knee
In infants under the age of three, septic arthritis usually affects the hip
Epidemiology:
Tow peaks in the age related incidence children < 5 years adult > 64 years> 75% of childhood SA previously healthy> 75% of adult onset SA predisposing factor
Etiology
Gonococcal
Non gonococcal
Gram-positive cocci (75-80%)
• Staphylococcus aureus (most common)
• Staphylococcus epidermidis
Immuncompromise, joint surgery
• β-Hemolytic Streptococci
• Streptococcus pneumoniae (polyarticular, bacteremia)
Hemophilia,Sickle cell disease
Older age, comorbidity
Microbiology :
Every bacterium has been reported to cause SA.
Staph. aureus 40-60%Streptococcus 9.5-28%S. pneumoniae 5.5-9.7%gram negative bacilli 9-19%Anaerobes 1.2-6%
Etiology Gram-negative bacilli (15-20%)
• E-coli• Pseudomonas IV drug abuse, immuncompromise Older age, Comorbidity, UTI
• Salmonella• Proteus SLE
Anaerobes (5-7%) Trauma, joint surgery
Clinical presentation:
Acute onset of pain and swelling in a single joint.
The pain is typically severe and occurs at rest.Large joints (knee, hip, ankle, shoulder)Fever 60-80% (mild)Chills (unusual)Warmth, tenderness, effusion and limited
active and passive range of motion
Polyarticular septic arthritis:
10-15%Two or more jointsS. aureus is the most common pathogenMore common in s. pneumoniae (36%)Streptococci, H-influenza, salmonella,
gonorrhoeae, anaerobesMany have comorbidity (RA, IVDA)Mortality
Risk factors :Prosthetic jointUnderlying joint diseases ( RA , OA )Age > 80 yearsRecent joint surgery Previous SADiabetes mellitus, hemodialysis, advanced hepatic
disease, malignancy, hemophilia, sickle cell disease, hypogammaglobulinemia, IV drug abuse, AIDS
Low social economic status Skin infection
Pathogenesis
Bacterial colonization
host immune response
Joint damage
Pathogenesis
Hematogenous seeding• Most common• Abundant vascular supply of synovium and lack of a limiting basement
membrane
Direct inoculation• Trauma • Joint surgery• Arthroscopy (<0.5%)• Joint aspiration and injection (0.0002%)• Osteomyelitis, cellulitis, or septic bursitis
Source of infection :
Hematogenous seeding (bacteremia): skin, lung, urinary tract, oral cavity, IV catheter Direct inoculation : joint aspiration and injection (0.0002 %) arthroscopic surgery (0.5 %)Spread from adjacent soft tissue infection or
osteomyelitis (hip and shoulder)
Pathogenesis
Microbial factors:
virulence
Attach to host tissue within joint Evade host defenses
Host factors:
Immune response Opsonization Phagocytosis cytokines
Clinical manifestations
Monoarticular, knee
• Febrile
• Acute onset of pain and swelling
• Warmth and tenderness, joint effusion, redness and limited
active and passive ROM
How is it diagnosed?
Diagnosis
History
PH/E
Arthrocentesis
Imaging
Diagnosis
Arthrocentesis Normal synovial fluid:
• Small amount
• Clear
• Highly viscous
• Few WBCs (<200)
• Protein concentration is one third of plasma
• Glucose concentration is similar to plasma
Diagnosis
Septic joint:
• Purulent
• Decreased viscosity
1. WBC > 50,000/mm³, PMN predominance
• Glucose less than half the serum glucose
The normal joint fluid is sterile and, if removed and cultured in the laboratory, no microbes will be detected.
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Organisms in septic arthritis• Gram -positive cocci
– S. aureus – S. pyogenes– S. pneumoniae – S. viridans group
• Gram-negative cocci– N. gonorrhoeae and meningitidis – H. influenzae
• Gram-negative bacilli– E. coli– Salmonella – Pseudomonas species
• Mycobacteria and Fungi
Diagnosis
Definite diagnosis: Gram-stained smear and culture of synovial fluid
• Smear: Gram-positive cocci: 50% - 75% Gram-negative bacilli: <50%
• Culture: 70% - 90%
• Blood culture: 40% - 50%
• Extraarticular site of infection
Diagnosis
Imaging: Plain radiographs
• Early stages: normal, soft tissue swelling
• Advanced infection: periosteal reaction, marginal or central erosions, destruction of subchondral bone, Bony ankylosis
• Baseline films should be obtained to look for evidence of other
disease and osteomyelitis
Copyright © 1972-2004 American College of Rheumatology Slide Collection. All rights reserved.
Staphylococcal arthritis: wrists (radiograph)
Copyright © 1972-2004 American College of Rheumatology Slide Collection. All rights reserved.
Septic arthritis: early and late changes, hip (radiographs)
Copyright © 1972-2004 American College of Rheumatology Slide Collection. All rights reserved.
Septic arthritis: sternoclavicular joint (technetium radioisotope scan)
Differential diagnosis
Crystal induced arthritis
RA
Reactive arthritis
Trauma
………………..
If septic arthritis is left untreated
Treatment: septic arthritis is suspected
blood and synovial fluid sample
empiric parenteral antibiotics based on gram stain
joint drainage
adjust antibiotics based on culture and sensitivity results
Treatment
Immediate treatment after clinical
evaluation and cultures
Appropriate antibiotics and adequate
drainage
Initial treatment is IV
Treatment
Gram-positive cocci• MSSA Nafcillin/Oxacillin 2gr IV q4h • MRSA Vancomycin
1gr IV q12h
Gram-negative bacilli Ceftriaxone/Cefotaxime 2gr IV q24h/ 2gr IV q8h
• Pseudomonas Piperacillin/Ceftazidime + AG
3gr IV q6h/ 2gr IVq8h
Treatment
No organism• Healthy, sexually active patient with community-acquired septic
arthritis
Ceftriaxone or Cefotaxime
• Elderly debilitated patient
Antistaphylococcal + Antipseudomonal
+ AG
Polymicrobial
Nafcillin/oxacillin + ceftriaxone/cefotaxime
Prognosis
Patients receiving immunosuppressive therapy
Serious underlying comorbidities (liver, kidney, or heart diseases)
Juxta-articular osteomyelitis
Disability: 25-50%
Mortality: 5-20%
Copyright © 1972-2004 American College of Rheumatology Slide Collection. All rights reserved.
Septic olecranon bursa
There are more than 150 bursae in the human body.
Superficial
Deep
Gonococcal arthritis
Neisseria gonorrhea
Clinical presentation:
• Disseminated gonococcal infection (DGI)
• Gonococcal septic arthritis
Most common cause of acute monoarthritis in sexually
active healthy young adults
DGI is more common in women than men (3/1)
Gonococcal arthritis
Clinical features
DGI
• Women/men: 3/1
• Intrauterine devices, menstruation, pregnancy, and pelvic operation
• Fever, shaking chills, skin lesions (vesiculopustular, hemmorhagic),
tenosynovitis (wrist, fingers, ankle, and toes), polyarthralgias, and arthritis
septic arthritis
• knee, wrist, ankle, or more than one joint
Gonococcal arthritis Diagnosis
DGI:
• Skin lesion culture: negative • SF culture: often negative• Blood culture: 50% positive• Culture from genital, rectal, and pharyngeal sites
Septic arthritis:
• SF culture: 50% positive• Blood culture: often negative
DNA-PCR
Gonococcal arthritis
Treatment
DGI:
• Ceftriaxone/cefotaxime 7-10 days
• Doxycycline
Septic arthritis:
• Ceftriaxone/cefotaxime 7-14 days
• drainage
Prosthetic joints infection
Epidemiology
• Knee: 1-2%
• Hip: 0.5-1%
• Shoulder: <1%
Prosthetic joints infection
Clinical manifestations Depend on the timing of infection:
Early (<3 m)
• Acquired during implantation
• Virulent pathogens such as S. aureus or gram-negative bacilli
• Joint pain, and effusion, wound drainage, fever,
implant site erythema, induration or edema, sinus tract
Prosthetic joints infection
Delayed (3 - 24 m)
• Acquired during implantation
• Less virulent pathogens such as S. epidermidis, P. acnes
• Persistent joint pain, with or without implant loosening, fever< 50% and
leukocytosis<10
Late (>24 m)
• Hematogenous
• S. aureus
• Joint pain, tenderness and swelling, fever, leukocytosis
Prosthetic joints infection
Treatment
Medical and surgical
• Organisms within biofilms are resistant to antibiotics: