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Acute Bronchitis (clinical practice + board review)


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What is Acute Bronchitis?

Acute bronchitis = inflammation of the bronchi (lower respiratory tract) due to an upper respiratory infection – this should not be confused with chronic bronchitis.

If the infection spreads further into the bronchioles and into the alveoli – then we have bronchopneumonia. The cough should be present for at least 5 days in order to consider the diagnosis.

The infection is usually viral in nature – which means antibiotics are not needed. But, you will often see Z packs given as the norm. Now, I’d be lying to you if I say I haven’t been guilty of this.

According to uptodate, it’s estimated that 60-90% of patients coming in to the clinic with acute bronchitis are also given antibiotics.

Why does this happen?

Well, it’s typically to appease the patient. Some patients believe with all their heart they will not get better unless they are given antibiotics. It’s also known that giving antibiotics without cause
can promote resistance.

This is a real problem to say the least. On an exam – you don’t give antibiotics. In clinical practice – you see it all the time. Some patients believe this so much, in fact, they may even
appear to get worse if not given the treatment they desire. All I can say is the mind is very powerful.

According to the CDC and the American College of Physicians, pertussis is the only URI that should be treated with antibiotics.

Etiology of Acute Bronchitis

Like we said, the majority of cases of acute bronchitis are going to be viral. Most notably: influenza A and B, parainfluenza, coronavirus, rhinovirus, and RSV. The only bacteria that
have been isolated in acute bronchitis are: mycoplasma pneumoniae, chlamydia pneumoniae, and pertussis.

Mycoplasma will typically present like a viral infection: pharyngitis, congestion, headache, and cough. It’s believed to be the culprit in less than 1% of cases.

Chlamydia can be seen in up to 5% of cases and will present with pharyngitis, cough, laryngitis, fever, and hoarseness.

Bordetella Pertussis aka whooping cough is only seen in about 1% of all cases. Those who have partial immunity will present identical to those having a viral cause. The only difference
will be the prolonged length of the cough (at least two weeks). The inspiratory whoop and post-tussive emesis are poor indicators for diagnosis.

Signs and Symptoms of Acute Bronchitis

How will patients present? The main symptom is going to be cough (may or may not be productive). The presence of sputum does not mean there is a bacterial etiology.  Presence of
color in the sputum also does not mean bacterial etiology. Hemoptysis can also be seen (this is the most common cause of hemoptysis).

If the patient has only been symptomatic for a few days, it will be almost impossible to differentiate this from a URI. But, it doesn’t matter. Management is the same.

The main differential is going to be pneumonia (which will require antibiotic therapy).

The main distinction will be high fever – fever may be present in both, but it’s more prominent in pneumonia. So, if you have high fever, productive cough, and malaise – you have to move away from bronchitis and move towards pneumonia or even influenza.

Wheezing can be present in both bronchitis and pneumonia. It’s characteristic to hear rhonchi in bronchitis that clears after coughing.

Physical exam findings that may signify pneumonia include: dullness to percussion, decreased breath sounds, rales, egophony and/or plural friction rub.

The cough in bronchitis can last up to 3 weeks.


Something I want to stress is to not confuse this with asthma. Please don’t tell your patients they have the beginning symptoms of asthma because they are coming in with cough, SOB,
and wheezing. The patient has an infection, which causes bronchospasm, which in turn presents with the same symptoms of asthma. The difference? These symptoms resolve when
the infection clears.

If you are truly worried that this may be the initial presentation – take a good history and offer PFT after their illness has resolved.

Testing in Acute Bronchitis

This is a clinical diagnosis and imaging isn’t really needed. The only reason to order an x-ray is if you are thinking the patient might have pneumonia (even then I would argue that the CXR
is unnecessary – I would go straight to therapy).

Indications for imaging: tachycardia, respiratory rate over 24, fever, rales, or signs of consolidation (features discussed above). It’s important to remember the elderly might not present with fever. So, you should have a lower threshold for pneumonia in the elderly.

Are cultures needed? No – remember it’s more than likely a viral infection.

There have been studies regarding procalcitonin and it’s correlation with bacterial infections. I have personally never ordered it. If a bacterial infection is present it is released from tissues because of direct stimulation. If a viral infection is present it seems to reduce the amount of procalcitonin in the serum by interferon gamma that is released from the viral infection.

Would I order it? I really don’t see the point. This is largely a clinical diagnosis. I would say if you are unsure – it’s best to give the antibiotic.

Treatment for Acute Bronchitis 

For the most part, you’re going to focus on symptom control.

Here’s the interesting part. The patient is coming in with a complaint of cough – but cough suppressants are not recommended. According to the data – they don’t work.

But, I give them and I typically give promethazine with dextromethorphan. Patients seem to respond well to this cough medication. If this doesn’t work I will try promethazine with codeine (only if the cough is severe).

There is also no evidence for the use of mucolytics, albuterol, and antihistamines. The one exception I would say is for those who come in wheezing. There is clearly narrowing of the
airways, and so, I only prescribe them in this scenario.

As stated, the only indication for antibiotic use is for the treatment of pertussis:
1. Erythromycin 500mg QID for 2 weeks
2. Clarithromycin 500mg BID for 2 weeks
3. Azithromycin 500mg for one day, followed by 250mg QD for 4 days.

Erythromycin can cause QT prolongation. Because of the regimen, azithroymcin is often preferred.

Lastly, antibiotic therapy may be warranted in the elderly (over 65) if they have been hospitalized in the last year, are on chronic steroids, have diabetes, or CHF. Also, consider therapy in those who are immunocompromised, at high risk for complication, and those over 80 years of age.