A case about how to reach the diagnosis of septic arthritis

1. VIGNETTE A
Done by:
Arwa H. Al-
Onayzan.
ID: 215007943.

2. OUR CASE
 An otherwise healthy 68 years old man.
 Complain of pain and swelling in the right knee.
 He doesn’t feel particularly ill.
 His temperature is 38.5 C.

3. LEARNING OBJECTIVES
1. What additional information do you need to obtain from this patient?
2. What aspects of physical examination are of particular relevance in
this case?
3. What additional diagnostic procedure would you perfume?
4. Suppose this patient has septic arthritis; which microorganism could
be responsible?
5. What would your treatment plan be?

4. WHAT ADDITIONAL INFORMATION DO
YOU NEED TO OBTAIN FROM THIS
PATIENT?

5. CON…
We confirm with patient whether :
 Is it one joint or more – mono versus poly
arthritis??
 Is it acute or chronic ??
 Is it recurrent ??
 Does the pain localized or general ?
 Does the pain radiate to other part of the body?
 Are there any aggravating or relieving factors ?

6. CON…
 Any associated inflammation (redness and warmth)?
 Any associated medical condition such as: DM, liver disease, and
trauma?
 Any one in your family member have the same complain or related
condition?Because in this case is one joint involvement so, it could be traumatic,
septic arthritis or psedogout.
We should ask about trauma. And ask of Recurrent acute episodes
usually MCP joint but can rarely affect knee is gout and if knee can be
pseudogout.
But in this case it look possibly septic arthritis.

7. WHAT ASPECTS OF PHYSICAL
EXAMINATION ARE OF PARTICULAR
RELEVANCE IN THIS CASE?

8. EXAMINATION OF THE JOINT
1. Look 3. Move2. Feel

9. CON…
 For example, If there is:
 Signs of erythema, swelling, warmth, and tenderness of knee.
 Infected joint exhibit an obvious effusion which is associated with
marked limitation of both active and passive ranges of motion.
 Signs and symptoms of infection such as fever.
 The affected joint associated with agonizingly painful held immobile by
muscle spasm.

10. WHAT ADDITIONAL DIAGNOSTIC
PROCEDURE WOULD YOU PERFUME?

11. COMPLETE BLOOD COUNT (CBC)
 Hemoglobin:
• Normochromic, normocytic anemia suggests chronic inflammatory and
autoimmune diseases.
• Hypochromic, microcytic anemia indicates iron deficiency or GI bleeding (Used
NSAID).
 White cell count:
• Neutrophilia is seen in bacterial infection (e.g. septic arthritis). It occurs with
use of corticosteroid.
• Lymphopenia occurs with viral illnesses or active systemic lupus
erythematosus (SLE).
• Neutropenia may reflect drug-induced bone marrow suppression.

12. CON…
Platelets:
Raised platelets occur with any chronic inflammation.
Thrombocytopenia is seen in drug induced bone marrow
suppression.

13. CON… (INVESTIGATION)
 Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP):
An increase of these reflects inflammation.
Plasma viscosity is also raised in inflammatory disease.
 Bone and liver biochemistry:
A raised serum alkaline phosphatase may indicate liver or bone
disease.
A rise in liver enzymes is seen with drug-induced toxicity.
 Serum uric acid: for gout.
 Antistreptolysin-O titre: in rheumatic fever.

14. CON… (INVESTIGATION)
 Joint aspiration:
Examination of joint fluid is used mainly to diagnose septic, reactive or
crystal arthritis.
The appearance of the fluid is an indicator of the level of inflammation.
The procedure is often undertaken in combination with injection of a
corticosteroid.
Aspiration alone is therapeutic in crystal arthritis

15. CON… (INVESTIGATION)
 Examination of synovial fluid:
Aspiration and analysis of synovial fluid are always indicated when an
infected or crystal induced arthritis is suspected, particularly a
monoarthritis.
Normal fluid is clear and straw colored and contains <3000
WBC/mm3.
Inflammatory fluid is cloudy and contains >3000 WBC/mm3.
Septic fluid is opaque and less viscous and contains up to 75 000
WCC/ mm3.

16. CON… (INVESTIGATION)
Polarized light microscopy is performed for crystals:
1) Gout:
 Negatively birefringent, needle-shaped crystals of sodium urate.
2) Pyrophosphate arthropathy (pseudogout):
 Rhomboidal, weakly positively birefringent crystals of calcium
pyrophosphate.

17. CON… (INVESTIGATION)
 Gram staining:
 Is essential if septic arthritis is suspected and may identify the
organism immediately.
 Joint fluid should be cultured and antibiotic sensitivities requested.

18. SUPPOSE THIS PATIENT HAS SEPTIC
ARTHRITIS; WHICH MICROORGANISM
COULD BE RESPONSIBLE?

19. CON…
 The organism that most commonly causes septic arthritis is
Staphylococcus aureus.
 Other organisms include:
 Streptococci, other species of staphylococcus, Neisseria
gonorrhoeae.
 Haemophilus influenzae in children,
 Other Gram-negative organisms in the elderly or complicating RA.

20. WHAT WOULD YOUR TREATMENT
PLAN BE?

21. WHAT WOULD YOUR TREATMENT
PLAN BE?
 Treatment should be started immediately because joint destruction may
occur within weeks.
 The joint should be immobilized initially and then physiotherapy started
early to prevent stiffness and muscle wasting.
 Intravenous antibiotics should be given for 1–2 weeks.
 It is usual to give two antibiotics to which the organism is sensitive for 6
weeks, then one for a further 6 weeks, orally.
Monitor clinically with the ESR and CRP.

22. EMPIRICAL TREATMENT IN SEPTIC
ARTHRITIS
 This is started before the results of culture are obtained.
 IV flucloxacillin 1–2 g is given 6-hourly, plus fusidic acid 500 mg orally 8-
hourly.
 If the patient is allergic to penicillin:
 Replace flucloxacillin with erythromycin 1 g i.v. 6-hourly or clindamycin 600
mg i.v. 8-hourly.
 In immunosuppressed patients, flucloxacillin 1–2 g i.v. 6-hourly plus
gentamicin.
 Change the antibiotics if the organism is not sensitive.
 Drainage of the joint and arthroscopic joint washouts are helpful in relieving
pain.

23. SUMMARY
 Carful history is very important to reach final diagnosis.
 Physical examination of the joint: Look  feel  move.
 Additional investigation that we can do in this case.
 The organism that most commonly causes septic arthritis is
Staphylococcus aureus.
 Treatment should be started immediately because joint destruction may
occur within weeks

24. REFERENCE
 Kumar and Clark's clinical medicine 8th Ch:11, (P532-533) and (P.
497).
 Merk manual (Nineteenth edition).