Following are the various micro -organism involved in osteomyelitis Age group Most common organisms Newborns (younger than 4 mo) S. aureus, Enterobacter species, and group A and B Streptococcus species Children (aged 4 mo to 4 y) S. aureus, 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 anemia patients Salmonella species are most common in patients with sickle cell disease REF: MAHESWARI 9TH ED