While acute bronchitis usually runs its course, complications such as secondary bacterial infection (“superinfection”) may occur in 5% to 10% of people.
Can Acute Bronchitis Become Chronic Bronchitis?
It’s important to note that, in addition to these complications, repeated episodes of acute bronchitis (especially in people who smoke or who are exposed to dust at work) can eventually lead to chronic bronchitis.
This progression from acute bronchitis to chronic bronchitis is an important reason to talk to your healthcare provider if you are experiencing repeated symptoms and to eliminate potential causes, such as smoking.
Secondary Infections
Secondary bacterial infections or “superinfections” are not uncommon following an episode of acute viral bronchitis and can both lengthen and worsen the illness.
Viral infections affect the body in a few ways that predispose to these infections:
Damage to the airways (the cilia that catch debris and bacteria) can make it easier for these foreign invaders to gain access to areas such as the sinuses or lungs.
Viral infections can also affect the immune system (for example, by reducing the number of macrophages that “eat” bacteria) such that bacteria are allowed to grow and multiply.
Viruses such as influenza may disrupt the normally tight junctions between the cells lining the airways such that bacteria can more easily attach to and penetrate these normal barriers. The buildup of bacteria in the airways that may occur with viral infections is referred to by scientists as “bacterial colonization.”
Bacteria that are commonly responsible for superinfections (and are often present on the skin and in the environment) include Streptococcus pneumoniae (the bacteria that causes pneumococcal pneumonia), Haemophilis Influenzae, and Staphylococcus aureus.
Some potential secondary infections include:
Middle ear infections (otitis media), especially in children
Sinus infections (sinusitis)
Pneumonia (discussed next)
Sepsis (occurs when bacteria multiply in the bloodstream causing a body side and often very serious infection)
Pneumonia
Pneumonia is the most common complication of viral acute bronchitis, occurring in roughly 5% of people. Among children aged 5 and over, as well as adults, the most common cause is Streptococcus pneumonia.
This is the reason why the pneumonia vaccine is recommended for children and for adults over the age of 65, as well as for people with lung conditions—such as COPD or asthma—or who are immunosuppressed for some reason.
In children under the age of 5, the most common cause of pneumonia is respiratory syncytial virus (RSV), which may be responsible for initial bronchitis as well as a secondary viral infection.