2. Septic arthritis Inflammation of a joint caused by a bacterial infection

3. Septic arthritis is also called infectious arthritis

4. Septic arthritis is diagnosed by identifying infected joint fluid

5. Epidemiology Incidence: General population 2-5/100,000/yr
Children /100,000/yr
RA /100,000/yr
Prosthetic joint /100,000/yr
Monoarticular (<20% more than one joint)
Large joints>small joints
Knee (>50%), ankle, wrist, hip, …

6. The most common joints to become infected are the knee In infants under the age of three, septic arthritis usually affects the hip

7. 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

8. 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

9. Microbiology : Every bacterium has been reported to cause SA.
Staph. aureus %
Streptococcus %
S. pneumoniae %
gram negative bacilli %
Anaerobes %

10. Etiology Gram-negative bacilli (15-20%) Anaerobes (5-7%) E-coli
Pseudomonas
IV drug abuse, immuncompromise
Older age, Comorbidity, UTI
Salmonella
Proteus
SLE
Anaerobes (5-7%)
Trauma, joint surgery

11. 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

12. Polyarticular septic arthritis:
10-15%
Two or more joints
S. aureus is the most common pathogen
More common in s. pneumoniae (36%)
Streptococci, H-influenza, salmonella, gonorrhoeae, anaerobes
Many have comorbidity (RA, IVDA)
Mortality

13. Risk factors : Prosthetic joint Underlying joint diseases ( RA , OA )
Age > 80 years
Recent joint surgery
Previous SA
Diabetes mellitus, hemodialysis, advanced hepatic disease, malignancy, hemophilia, sickle cell disease, hypogammaglobulinemia, IV drug abuse, AIDS
Low social economic status
Skin infection

14. Bacterial colonization
Pathogenesis
Bacterial colonization
host immune response
Joint damage

15. Pathogenesis Hematogenous seeding Direct inoculation 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

16. Source of infection : Hematogenous seeding (bacteremia):
skin, lung, urinary tract, oral cavity, IV
catheter
Direct inoculation :
joint aspiration and injection ( %)
arthroscopic surgery (0.5 %)
Spread from adjacent soft tissue infection or osteomyelitis (hip and shoulder)

18. Pathogenesis Microbial factors: virulence
Attach to host tissue within joint
Evade host defenses
Host factors:
Immune response
Opsonization
Phagocytosis
cytokines

19. Clinical manifestations
Monoarticular, knee
Febrile
Acute onset of pain and swelling
Warmth and tenderness, joint effusion, redness and limited active and passive ROM

21. How is it diagnosed?

22. Diagnosis
History
PH/E
Arthrocentesis
Imaging

23. 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

24. Diagnosis Septic joint: Purulent Decreased viscosity
WBC > 50,000/mm³, PMN predominance
Glucose less than half the serum glucose

25. The normal joint fluid is sterile and, if removed and cultured in the laboratory, no microbes will be detected.

26. 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
Organisms in septic arthritis #
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27. Diagnosis Culture: 70% - 90% Blood culture: 40% - 50%
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

28. Diagnosis Plain radiographs Imaging: 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

29. Staphylococcal arthritis: wrists (radiograph)
The septic arthritis of the wrist on the right is caused by a staphylococcal infection. The carpus and adjacent bones reveal soft-tissue swelling and localized osteopenia. There is narrowing of multiple joints and irregularity of adjacent bony margins. The left wrist is normal. #
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30. Septic arthritis: early and late changes, hip (radiographs)
Left, The anteroposterior view of the hip shows narrowing of the joint space without reactive bone change or osteopenia.
Right, Destruction and flattening of the weight-bearing surface of the femoral head have occurred. Some osteopenia is also present. Diffuse loss of cortex (rather than focal erosion) is characteristic of septic arthritis, as demonstrated in both the femoral head and the acetabulum. #
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31. Septic arthritis: sternoclavicular joint (technetium radioisotope scan)
The technetium radioisotope scan demonstrates increased uptake in the medial aspect of the left clavicle (arrow) and medial aspect of the anterior left first rib (short arrow). The two sites are separated more than usual, indicative of a soft-tissue lesion, which, in this case, was secondary to a joint-space infection caused by Staphylococcus aureus. #
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32. Differential diagnosis
Crystal induced arthritis RA
Reactive arthritis
Trauma
………………..

33. If septic arthritis is left untreated

34. 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

35. Treatment Immediate treatment after clinical evaluation and cultures
Appropriate antibiotics and adequate drainage
Initial treatment is IV

36. Treatment Gram-positive cocci 1gr IV q12h Gram-negative bacilli
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

37. Treatment Ceftriaxone or Cefotaxime
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

38. Prognosis Disability: 25-50% Mortality: 5-20%
Patients receiving immunosuppressive therapy
Serious underlying comorbidities (liver, kidney, or heart diseases)
Juxta-articular osteomyelitis
Disability: 25-50%
Mortality: 5-20%

39. Septic olecranon bursa
Marked tenderness, swelling, and erythema are present over the olecranon bursa. A purulent serosanguinous drainage is seen exuding from the bursa after needle puncture. Staphylococcus aureus was cultured from the drainage. #
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40. There are more than 150 bursae in the human body.
Superficial
Deep

41. 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)

43. Gonococcal arthritis Clinical features DGI septic arthritis
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

44. Gonococcal arthritis Diagnosis DGI: Septic arthritis: DNA-PCR
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

45. Gonococcal arthritis Treatment DGI: Septic arthritis:
Ceftriaxone/cefotaxime days
Doxycycline
Septic arthritis:
Ceftriaxone/cefotaxime days
drainage

46. Prosthetic joints infection
Epidemiology
Knee: 1-2%
Hip: 0.5-1%
Shoulder: <1%

47. 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

48. Prosthetic joints infection
 Delayed ( 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

49. Prosthetic joints infection
Treatment
Medical and surgical
Organisms within biofilms are resistant to antibiotics: