Table 1. Bacteria Which Are Most Commonly Isolated from Synovial Fluid of Patients with Bacterial Arthritis*


Gram-positive strains

Staphylococcus aureus  

Staphylococcus epidermidis, and other coagulase negative staphylococci


                        Streptococcus pyogenes

                        Streptococcus pneumoniae

                        Streptococcus agalactiae


Gram-negative strains

            Neisseria gonorrhoeae

            Escherichia coli

            Neisseria meningitides

 * Any strain, including anaerobes, which causes bacteraemia may invade joint tissues and elicit bacterial arthritis



Table 2  Risk Factors for the Development of Septic Arthritis

Old age (>80 years)

Rheumatoid arthritis

Immunosuppressive therapy

Prosthetic joint

Previous intra-articular corticosteroid injection

Diabetes mellitus


Low socioeconomic status


Cutaneous ulcers

Trauma penetrating into the joint



Table 3 Differential Diagnosis for Acute Monoarthritis


Septic arthritis



Rheumatoid arthritis

Apatite-related arthropathy

Reactive arthritis

Lyme arthritis

Transient synovitis of the hip

Pigmented villonodular synovitis


Neuropathic arthropathy


Intra-articular injury (fracture, meniscal tear, osteonecrosis)

Metastatic carcinoma




Table 4. Bacterial Infections Associated with the Development of Reactive Arthritis


Enteritis caused by


                        Various serovars


                        S. flexneri

                        S. dysenteriae

                        S. sonnei


                        Y. enterocolitica (especially O:3 and O:9)

                        Y. pseudotuberculosis


                        C. jejuni

                        C. coli

            Clostridium difficile

Urethritis caused by

            Chlamydia trachomatis

            Mycoplasma genitalium*

            Ureaplasma urealyticum*

Upper respiratory infection caused by

            Group A beta-haemolytic streptococcus**

            Chlamydia pneumoniae


* causes urethritis, but the role in reactive arthritis still discussed;

** typically causes acute rheumatic fever, but has been described to cause ‘reactive-like’ arthritis


Table 5. Clinical Features of Reactive Arthritis in Hospital Series


Number of joints,  range



Low back pain, range  (%)


X-ray sacroilitis, range (%)


Urethritis, mean, range (%)


Conjunctivitis, range  (%)


Iritis, range  (%)


Skin lesions, range (%)

  - erythema nodosum

  - pustules

  - keratodermia


Duration of arthritis, range, months


Chronic course (>12 months), range (%)


HLA-B27 + , range (%)



Table 6. Revised Jones Criteria for Acute Rheumatic Fever [8] 

Major manifestations

Minor manifestations

Laboratory findings







Elevated acute-phase reactants:

a) C-reactive protein (CRP)

b) Erythrocyte sedimentation rate (ESR)





Previous rheumatic fever or rheumatic heart disease


Prolonged P-R interval in ECG


Erythema marginatum


Subcutaneous nodules


Supporting evidence of preceding streptococcal infection:

a) Increased ASO or other streptococcal antibodies

b) Positive throat culture for Group A-haemolytic streptococci

c) Recent scarlet fever


Table 7. Musculoskeletal Features of Borreliosis with Respect to Geographical Areas. Adapted from [9] 

Clinical symptom

Europe and Asia (B. afzelii, B. garinii, B. burgdorferi ss)

North America (B. burgdorferi ss)

Arthritis, acute

Oligoarthritis (less frequent)

Less intense joint inflammation


Oligoarthritis (more frequent)

More intense joint inflammation


Arthritis, chronic

Persisting arthritis less frequent

Treatment-resistant arthritis in about 10% of the patients


Table 8. Arthritis and Autoimmune Diseases Associated with Parvovirus B19 Infection


Type of arthritis

Other autoimmune features

Other manifestations




Antiphospholipid syndrome


Rash, haematological changes, hepatitis, myocarditis, myositis, CNS symptoms


SLE, systemic lupus erythematosus; CNS, central nervous system


Table 9. Alphaviruses Related to Articular Symptoms. Adapted from [11] 


Clinical features

Epidemiological area


Fever, arthralgia/arthritis, rash, myalgia, chronic joint pain, haemorrhagic symptoms, paresthesias

Africa, India, South East Asia, Philippines


Fever, arthralgia/arthritis, chronic joint pain, rash, myalgia, haemorrhagic symptoms

Trinidad, Surinam, Brazil, Colombia, Bolivia


Fever, arthralgia/arthritis, chronic joint pain, rash, myalgia, haemorrhagic symptoms, paresthesias

Uganda, Kenya, Tanzania, Malawi, Senegal

Barmah Forest

Fever, arthralgia/arthritis, rash, myalgia


Igbo Ora

Fever, arthralgia, rash, myalgia

Ivory Coast

Ross River

Fever, polyarthritis, chronic arthralgia,  rash, paresthesias, glomerulonephritis

Australia, New Guinea, Fiji, The Solomon Islands, American Samoa, South pacific Islands


Fever, rash, arthralgia/arthritis, paresthesias

Europe, Africa, Australia, Asia, Philippines


Fever, arthralgia/arthritis, rash, chronic joint pain, paresthesias

Sweden, Norway



Fever, arthralgia/arthritis, chronic arthritis, rash,



Karelian fever

Fever, arthralgia, rash



Table 10. Antibiotic Treatment of Septic Arthritis. Adapted from  [4,16] 

Patient group

Antibiotic choice

No risk factors for atypical organism

Staphylococcal penicillin (e.g. cloxacillin or flucloxacillin) 2 g four times a day i.v.

Fusidic acid 500 mg three times a day p.o, or gentamicin i.v. may be added.

In the case of penicillin allergy, clindamycin 450-600 mg for times a day, or 2nd or 3rd generation cephalosporin may be given

High risk of Gram negative sepsis

2nd or 3rd generation cephalosporin (e.g. cefuroxime 1.5 g three times a day).

MRSA (methicillin resistant Staphylococcus aureus) risk

Vancomycin plus 2nd or 3rd generation cephalosporin

Suspected gonococcus or meningococcus

Ceftriaxone 1 g once a day (im. or iv) or similar drugs, depending on local policy/resistance

I.V. drug users

Discuss with microbiologist

Intensive therapy unit patients, known colonization of other organs

Discuss with microbiologist


Figure 1: Septic Arthritis


Figure 2: A Pustule at Early Phase of Disseminated Gonococcal Infection


Figure 3: A Pustule With Necrotic Centre In A Patient With

Disseminated Gonococcal Infection


Figure 4: Fulminant Knee Synovitis In A Patient With Reactive Arthritis


Figure 5: Dactylitis Of Left 2. Toe And Right 4. Toe

In A Patient With Reactive Arthritis



Figure 6: Skin Lesions In A Patient With Reactive

Arthritis Due To Salmonella Infection



Figure 7:  A Patient With Acute Gouty Arthritis In The Foot



Figure 8. Erythema Nodosum



Figure 9: Bilateral Hilar Lymphadenopathy In A Patient With Acute Sarcoidosis


Figure 10:. Clinical Approach  In A patient Who PresentsWith Fever and Acute Arthritis (A),

and With Fever, Arthritis, and Extra-Articular (B) Symptoms.

ReA=Reactive Arthritis; HIV=Human Immunodeficiency Virus; Gc=Gonococcal; EN=Erythema Nodosum; EM=Erythema Migrans.


Figure 11: Radiology Of The Ankle In A Patient With Septic Arthritis (Same Patient As In Fig. 1)



Figure 12: Radiology Of Left Knee In A Patient Rheumatoid Arthritis With

Septic Arthritis In A Knee With Prosthesis




Figure 13: Indium-111 Labeled Leucocyte Scan In A Patient With

Septic Arthritis (Same Patient As In Fig. 12)




Figure 14: Three-Phase Bone Scan With Technetium-99m Labeled

Diphosphonates In A Patient With Septic Arthritis (Same Patient As In Fig. 12)