studies have found over 70% of cases due to MRSA Osteomyelitis due to MRSA has been associated with a longer duration of fever, extended hospitalization, and increased frequency of complications Group A β-hemolytic streptococcus and Streptococcus pneumoniae are the next most common organisms isolated in childhood osteomyelitis and together account for 10% of cases outside of the neonatal period The frequency of K kingae has been increasing and is most commonly reported in the toddler and preschool age group It is difficult to culture and the increased incidence may be due to improved success in identification through polymerase chain reaction (PCR) and improved culture techniques It is a gram-negative organism and therefore resistant to vancomycin and clindamycin, but sensitive to cephalosporins and β-lactam antibiotics Bacterial isolates from neonates younger than months include S aureus, group B streptococcus, and Escherichia coli ( Table 121.1 )