While the physician awaits results, the infant may be admitted to the hospital and treated with antibiotics that target the bacteria most likely to cause an infection in infants. Commonly used antibiotics include ampicillin and ceftriaxone or cefotaxime. Sometimes an injection of antibiotics is given in the muscle and the child is sent home for close observation. The cultures from blood, urine, or CSF are monitored for 48 hours; if they remain free of any bacterial growth, the antibiotics are stopped and if the infant was hospitalized, he or she is sent home. However, if the cultures grow any bacteria, the antibiotic regimen may be changed to one that targets the specific bacteria identified. The length of the treatment will vary depending on the severity of the infection.