Final answer:
Neonatal osteomyelitis is the condition when a person less than 4 months old is diagnosed with osteomyelitis, an inflammation of bone tissues usually caused by bacterial infection.
Step-by-step explanation:
The condition called when a person is less than 4 months old and has osteomyelitis is known as neonatal osteomyelitis. Osteomyelitis is an inflammatory condition of bone tissue which is commonly caused by bacterial infection. Neonates, defined as infants within the first four weeks after birth, can develop this condition from bacteria such as S. agalactiae transmitted during childbirth or from other sources if the infection occurs after the neonatal period but within the first few months of life.