Pediatric bone and joint infections: Clinical

Bone and joint infections comprise mostly of osteomyelitis and septic arthritis, or a combination of the two.

In osteomyelitis, infections most often occur at the ends of long bones where they meet to form joints like the hip and knee, and in septic arthritis, they occur in the joints.

The source of infection may be hematogenous, secondary to close-by infection or secondary to direct inoculation from trauma and surgery.

Diagnosis is mostly clinical, and it’s based on the rapid onset and localization of symptoms.

Individuals mostly present constitutional symptoms like irritability, decreased appetite or activity, tachycardia, malaise, and fever.

Local signs consist of warmth, swelling, point tenderness around a bone or joint, and cellulitis. Joint stiffness is also common, with single joint involvement being more characteristic for bacterial infections.

If the clinical signs raise suspicion of infection, the next step is asking for additional tests to confirm or infirm diagnosis.

Let’s start with osteomyelitis, which is an infection of the bone. It is usually caused by Staphylococcus aureus, with community-acquired methicillin-resistant S. aureus or MRSA accounting for many of the cases, especially in posttraumatic, post-surgical, and vertebral osteomyelitis.

Vertebral osteomyelitis is also caused by Mycobacterium tuberculosis in about a quarter of the cases.

Additionally, Salmonella species and Streptococcus pneumoniae are commonly found in those with sickle cell disease; Gram-negative bacteria, such as Pseudomonas species or Escherichia coli, are common in infections after puncture wounds of the feet or open injuries to bone, and Staphylococcus epidermidis in some of those with prosthetic devices.