Osteomyelitis is a bone infection that is usually caused by bacteria. Some of the bacteria that lead to this condition are described below.

• In newly born babies aged less than four months, the condition is mainly caused by Staphylococcus aureus, group A and B Streptococcus species andEnterobacter species.
• In children aged between 4 months and 4 years, the most common causes are group A Streptococcus, S. aureus, Enterobacter species and Haemophilus influenzae.
• In children and teenagers aged between 4 and 18 years, osteomyelitis is mainly caused by group A S. aureus, H. influenzae and Enterobacter species.
• Adults are usually infected with S aureus and sometimes with Streptococcus and Enterobacter species.
• Those with sickle cell anemia are more likley to develop osteomyelitis due to Salmonella.
• Osteomyelitis may occur as a complication of pulmonary tuberculosis. Mycobacterium tuberculosis spreads to the bone via the bloodstream.
• Other organisms that can cause osteomyelitis include Pseudomonas aeruginosa, E.coli, and Serratia marcescens.

In the majority of cases, osteomyelitis affects the long bones in the leg, but the condition can also affect other bones such as those in the arm. In children, osteomyelitis generally affects the long bones, while in adults infection of the pelvis and vertebrae is more common. Acute osteomyelitis mainly occurs in children, while the chronic form of the condition is usually caused by a compromised immune system and tends to affect people with HIV or those taking immunosuppressive agents such as corticosteroids.