Bone & Joints Infections

Osteomyelitis Osteomyelitis is infection of the bone. Infections can reach a bone by traveling through the bloodstream, spreading from nearby tissue or begin in the bone itself after an injury. Common involved bones: o In children: long bones of the legs and upper arm. o In adults: the vertebrae. o In Diabetics: osteomyelitis may complicate foot ulcers.

Diabetic septic foot

Symptoms and signs: Fever & chills. Pain, swelling, warmth and redness over the area of the infection. Sometimes osteomyelitis causes no signs and symptoms or signs and symptoms that are difficult to distinguish

Causes: Microorganisms can enter the bone in a variety of ways: Via the bloodstream (Hematogenous: bacteria from distant infection deposit in a weak spot of the bone). From a nearby infection (internal source: joint infection or deep tissue infection). Direct contamination (external source: bone fracture or surgery).

Causative Agents of Osteomyelitis: S. aureus is the most common causative organism in all patients Age groupMost common organisms Newborns ≤ 4 months Enterobacter species, and group A and B Streptococcus species Children ≤ 4 yrs group A Streptococcus species, Haemophilus influenzae, and Enterobacter species Children, adolescents (aged 4 y to adult) S. aureus (80%), group A Streptococcus species, H. influenzae, and Enterobacter species Adult S. aureus and occasionally Enterobacter or Streptococcus species Sickle cell anemiaSalmonella species. S. aureus is still most likely. Vertebral osteomyelitisStaphylococci (50%), and Tuberculosis (50%).

Acute Osteomyelitis  Vertebral osteomyelitis can occur in adults secondary to a UTI or prostatitis. Or bone tuberculosis (Pott’s disease )  Candidemia from infected central venous catheters can lead to fungal osteomyelitis  Causative bacteria related to primary focus includes: gram positive cocci, gram negative bacilli, anaerobes or poly- microbial infection esp. in diabetics.

Bones are resistant to infection. Risk factors include: o Injury or orthopedic surgery: bone fracture, deep puncture wound, surgery, deep animal bites. o Circulation disorders: Poorly controlled diabetes, arterial disease (smoking), sickle cell disease. o Intravenous lines or catheters: Dialysis machines. o Impaired immune system: Chemotherapy, organ transplant, corticosteroids. For unclear reasons people with HIV/AIDS don't seem to have an increased risk of osteomyelitis. o Drugs users: Non sterile needles, unsterilized skin before injections.

Complications  Bone death (osteonecrosis and sequestrum formation).  Septic arthritis.  Impaired growth  Permanent deformities.  Skin cancer

Tests and diagnosis o Imaging tests X-rays Computerized tomography (CT) scan Magnetic resonance imaging (MRI) o Blood culture: positive in 33% of cases o Bone aspiration or biopsy: if blood culture are negative.

Treatments: Hospitalization is usually necessary Antibiotics: according to sensitivity results. Should be given intravenously and then orally for at least six weeks. Surgery: to drain the infected area, remove necrotic bone, remove prosthetics or any foreign object, restore blood flow to the bone or to amputate the limb.

Arthritis Inflammation of the joint space. Usually affects a single joint. Symptoms: Fever, pain, swelling, limitation of movement. Risk factors: age, diabetes, immunosuppression, IV drug use, catheters, prior joint damage, sexually transmitted diseases.

Two types: o Septic (suppurative) arthritis: bacterial infection. o Non septic: gout, rheumatoid arthritis, viral Source of infection in septic arthritis: o Internal: o Hematogenous (the most common) o Near infected bone. o External: Trauma, arthroscopy or surgery.

Etiology:  Neisseria gonorrhoeae (gonococcal arthritis) is the leading cause in sexually active adults.  Non gonococcal: S. aureus is the most common causative bacteria and affects all age groups.  Other bacteria include: streptococci, gram negative bacilli and spirochetes (Lyme disease).

 Prognosis & complications:  Gonococcal arthritis has an excellent outcome.  Nongonococcal arthritis can result in scarring with limitation of movement in 50% of cases. Risk factors for complications include: Age, prior rheumatoid arthritis, poly-articular joint involvement, hip or shoulder involvement, virulent pathogens and delayed initiation or response to therapy.

Diagnosis: Examination of synovial fluid: cloudy with high number of WBCs especially neutrophils. Gram stain. Culture: Blood, synovial fluid or skin lesions culture. PCR: synovial fluids or urine.

Treatment: Drainage of infected synovial fluid by aspiration (arthrocentesis) or surgically. Antimicrobial therapy: should be directed at suspected and susceptibility results. Given parentally then orally for 3- 4 weeks. Gonococcal & Enterobacteriaceae arthritis: Ceftriaxone Ciprofloxacin Nongonococcal arthritis: MSSA: nafcillin or cefazolin. MRSA: Vancomycin. Pesudomonas: piperacillin and Aminoglycoside. Animal bite : Ampicillin-Sulbactam. Lyme disease arthritis: Doxycycline