Final answer:
Frequent bacterial infections in a young child, especially of the skin, lung, and sinus, can be caused by bacterial rhinosinusitis and secondary infections after viral respiratory tract infections. Prompt diagnosis and treatment are important.
Step-by-step explanation:
Frequent bacterial infections in a young child, especially of the skin, lung, and sinus, can be caused by several factors. One possible cause is nasal colonization with opportunistic pathogens, which can lead to bacterial rhinosinusitis. This occurs when an initial viral infection weakens the immune system, allowing opportunistic bacteria like S. pneumoniae, H. influenzae, and M. catarrhalis to cause infection and inflammation in the sinus cavities. Bacterial infections can also occur as secondary infections after a viral respiratory tract infection, such as pneumonia caused by Haemophilus influenzae. It is important to diagnose and treat these infections promptly to prevent complications and promote recovery.