Septic Arthritis of the Knee


Crystal arthritides

Trauma

Gout

Soft tissue injury

Pseudogout

Spontaneous haemarthrosis
 
Fracture

Inflammatory arthritides
 
Rheumatoid arthritis

Infection

Psoriatic arthritis

Acute bacterial septic arthritis

Reactive arthritis including Reiter’s disease

Viral septic arthritis

Ankylosing spondylitis

Fungal septic arthritis

Enteropathic associated arthropathies

Mycobacterial septic arthritis

Lupus

Lyme disease

Familial mediterranean fever

Acute rheumatic fever

Other

Tumour/Metaplasia

Osteoarthritis

Pigmented villous nodular synovitis

Avascular necrosis

Synovial chondromatosis

Ochronosis

Sarcoma
 
Hypertrophic pulmonary osteoarthropathy



Septic arthritis is the invasion of a joint by a microorganism that generates a purulent response. In the majority of cases the responsible organism is a bacterium and acute bacterial septic arthritis will form the focus of this chapter, however other pathogens including viruses and fungi may also directly infect joints. Reactive arthritis is a separate condition whereby infection elsewhere in the body, commonly the upper respiratory tract, genitourinary system or bowel, leads to joint inflammation.



12.2 Risk Factors


Numerous risk factors exist for septic arthritis (Table 12.2), with skin infection being the most significant. Following arthroscopic surgery, septic arthritis is relatively uncommon with a reported incidence of 0.14 % [5], though infection following anterior cruciate ligament reconstruction is more common with 0.14–2.6 % of procedures affected [6]. The risk of joint infection following intra-articular corticosteroid injection is low with a reported incidence of 0.04 % [2]. Systemic conditions that are associated with the condition include diabetes mellitus, chronic renal failure, malignancy and alcohol abuse. Diabetic patients are at increased risk of septic arthritis due to immune system suppression, propensity to skin infections and ulceration, and the potential requirement for haemodialysis [7]. In a study from the Netherlands, increased age, particularly over 80 years, was associated with an increased risk of septic arthritis [5]. Conditions that lead to joint injury, in particular rheumatoid arthritis and to a lesser extent osteoarthritis, also confer an increased risk of joint infection [2]. The use of anti-tumour necrosis factor alpha (TNFα) therapies is reported to double the risk of septic arthritis in patients with rheumatoid disease [8]. Intravenous drug abusers are at greater risk than the general population of developing polymicrobial septic arthritis, potentially with atypical pathogens including fungi.


Table 12.2
Risk factors for septic arthritis





























Extremes of age

Low socioeconomic status

Diabetes mellitus

Chronic renal failure

Malignancy

Rheumatoid arthritis

Osteoarthritis

Alcohol abuse

Intravenous drug abuse

Knee surgery/intra-articular injection

Cutaneous ulcers/skin infection

Immunodeficiency


12.3 Causative Agents


The aetiological agents for septic arthritis vary with age (Table 12.3), but in all age and risk groups, the principal causative organism is Staphylococcus aureus followed by other Gram-positive organisms, particularly streptococci [2]. S. aureus has a strong predilection for joints due to the presence of multiple microbial surface components that facilitate binding to joint extracellular matrix. Some strains of S. aureus (the Panton-Valentine Leukocidin complex) are producers of cytotoxins and can survive within neutrophils; these can be responsible for severe joint infections in otherwise healthy individuals [9]. The finding of methicillin resistant strains of S. aureus (MRSA) causing septic arthritis has been a particularly worrying trend over the past decade [2].


Table 12.3
Agents responsible for septic arthritis






























































































































































































































































































Patient group

Aetiological agent

Source

Neonates

Group B streptococci

Maternal-foetal transmission
 
Escherichia coli
 
 
Staphylococcus aureus
 

Children (<3 years old)

Streptococcus pyogenes

Bacteraemia
 
Streptococcus pneumoniae
 
 
Staphylococcus aureus
 
 
Kingella kingae
 
 
Haemophilus influenzae
 

Adolescents

Neisseria gonorrhoea
 
 
Pseudomonas aeruginosa
 
 
Kingella kingae
 
 
Staphylococcus aureus
 

Adults

Gonococci

Genitourinary tract or pharyngeal infection
 
Staphylococcus aureus

Bacteraemia
 
Streptococci
 
 
Haemophilus influenzae
 
 
Pseudomonas aeruginosa
 
 
Kingella kingae
 
 
Moraxella osloensis
 
 
Arcanobacterium haemolyticum
 
 
Mycoplasma hominis
 
 
Mycobacterium marinum
 
 
Shigella sp
 
 
Salmonella sp
 
 
Ureaplasma urealyticum
 

Bite wounds
   

Human

Eikenella corrodens
 
 
Staphylococcus aureus
 
 
Group B streptococci
 
 
Oral anaerobes
 

Rat

Staphylococcus aureus
 
 
Streptobacillus moniliformis
 
 
Spirillum minus
 
 
Streptococci
 

Cat/dog

Staphylococcus aureus
 
 
Pasteurella multocida
 
 
Pseudomonas sp
 
 
Moraxella sp
 
 
Haemophilus sp
 

Elderly

Streptococci
 

Concomitant diseases

Enterobacter
 
 
Pseudomonas aeruginosa
 
 
Serratia marcescens
 
 
Salmonella sp
 

Immunocompromised

Mycobacterium tuberculosis
 

Intra-articular injections

Mycobacterium kansasii
 

Arthroscopy

Mycobacterium marinum
 

HIV associated

Mycobacterium avium-intracellulare complex
 
 
Mycobacterium fortuitum
 
 
Mycobacterium haemophilum
 
 
Mycobacterium terrae
 
 
Mycobacterium chelonae
 
 
Nocardia asteroides
 

Viruses

Parvovirus B19
 
 
Hepatitis B or C
 
 
Rubella
 
 
Togavirus
 
 
Chikungunya virus
 
 
Varicella
 
 
Mumps virus
 
 
Adenovirus
 
 
Coxsackie A9, B2, B3, B4
 
 
Retroviruses – HIV
 
 
Epstein-Barr virus
 
 
O’nyong nyong
 
 
Ross River
 
 
Barmah forest virus
 
 
Ockelbo agent
 

Fungi

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Nov 17, 2017 | Posted by in MUSCULOSKELETAL MEDICINE | Comments Off on Septic Arthritis of the Knee
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