Persistent Bacterial Bronchitis

I am sure many of you would have suffered through those persistent and incessantly annoying coughs that completely disrupt the flow of your day and make you feel miserable. Often, it’s due to allergies or colds but sometimes it can have deeper clinical roots. In this article, we focus on one of those perhaps lesser-known causes, Persistent Bacterial Bronchitis. This article provides a brief insight into the disease broadly covering its causes, symptoms & treatment.

What is persistent bacterial bronchitis (PBB)?

Persistent Bacterial Bronchitis (PBB) also known as Protracted bacterial bronchitis (or Chronic suppurative lung disease OR Persistent Endobronchial Infection) is a rather frequent cause of chronic cough.1 Chronic cough itself is defined as a cough lasting for 4 weeks or more. PBB affects approximately 40% of the pediatric (young children) population who are referred to specialists for the management of chronic wet cough. Diagnosis of the disease is primarily done clinically and usually, instrumental examination (examinations that involve procedures such as echocardiography) is not required.2 Interestingly, although the disease was recognized clinically in 2006, physicians have been known to describe similar conditions from many decades ago.3

To further understand the mechanics behind Persistent Bacterial Bronchitis more clearly, it is important to investigate its causes.

What are the causes of PBB?

As such, there aren’t any defined and specific causes of Persistent Bacterial Bronchitis, but doctors and researchers have postulated several theories, one line of thinking is that if a child has been frequently run down with viral illness throughout childhood – this could injure and cause inflammatory reactions in their airways making it easier for bacteria to attack those areas and breed there.1

 How is PBB different from other causes of cough?

 At this point through reading this article, you might be wondering how one could differentiate the cough caused by PBB from the coughs caused by other diseases. This is another tricky area where there are no definite answers but there might be some clues that can help. Some of the most common causes of cough include upper respiratory tract infections (these include Common Cold, Epiglottitislaryngitis (inflamed voice box), Pharyngitis (sore throat), etc.). However, cough and in fact most of the symptoms from these groups of infections last 10 to 14 days and in worst-case scenarios, maybe 4 weeks.4 This is in stark difference to the chronic nature of symptoms brought about by PBB. PBB coughs are also primarily wet coughs with mucus productions. They can also be wheezy (refers to a whistling or rattling sound heard when breathing) in nature making them similar to what is heard in asthmatic cases. However, it can be distinguished from asthmatic coughs since it does not resolve with inhalers.1

Other causes of chronic productive (and wet) cough could include long-term lung diseases such as Cystic Fibrosis, Chronic Bronchitis, Bronchiectasis, or Eosinophilic Bronchitis.5 There isn’t a clear way to differentiate the cough caused by PBB and these diseases and hence the best course of action would be to see your healthcare provider to come to a definite conclusion.

What are the symptoms of PBB?

As with any disease, it is very important to know the common telltale signs that indicate the presence of illness. The onset of symptoms in Protracted Bacterial Bronchitis is similar to that of common cold and lower respiratory tract infections. However, the other symptoms resolve rather quickly leaving only a persistent and long-term wet cough. Physicians also include rhinosinusitis (inflammation of the nasal cavity & paranasal sinuses causing symptoms like nose congestion) in their differential diagnosis of PBB.6

Link between major airway injuries and PBB

Airway deformities have the potential to cause PBB. Doctors have asserted that children with tracheomalacia are at higher risk of developing the disease. Tracheomalacia (trachea refers to the windpipe and malacia means ‘softening’) essentially often occurs in newborns (between 4 to 8 weeks) and entails the underdevelopment of the cartilage of the trachea which means that the walls that make up the trachea end up being soft and ‘floppy’ in nature rather than being rigid. As you can probably imagine, this leads to breathing issues.7 This nature of the tracheal walls can also cause entrapment of mucus and therefore lead to PBB.1

Immunity in children with PBB

Children with PBB do not generally showcase any immune system deficiencies and hence have normal antibody levels (this is a protective substance made by the immune system when a foreign substance, such as a disease-causing organism, enters the body).8

Research has further indicated that in children with PBB, the neutrophil levels are usually high (these are cells that are a pertinent part of the immune system in that they are the first to respond to the infiltration of bacteria/virus and can destroy these microorganisms by ingesting and destroying them).

How is PBB diagnosed?

As with any disease, it can be helpful to know how PBB is diagnosed There are three criteria that physicians use and they are as follows:3

  1. Patient has chronic cough/productive cough (cough with sputum production)
  2. Their Bronchoalveolar pathways (Broncho meaning airways to the lungs and alveolar meaning air sacs in the lungs) are infected with bacteria such as Haemophilus influenzaeStreptococcus pneumoniae, and Moraxella catarrhalis
  3. The cough resolves following a 2-week antibiotic course

In addition, chest x-rays may be conducted but this is usually done to rule out other issues as x-rays cannot indicate specific signs of PBB. The physician may also carry out lung function testing. Furthermore, in order for your healthcare provider to provide more specific antibiotics for treatment, they may carry out a sputum (phlegm) culture as this can help them identify the specific bacteria(s) causing the issues.

What are the treatment options for PBB?

Having looked at the symptoms, causes and diagnostic criteria let’s now look at the treatment available for Persistent Bacterial Bronchitis. Usually, a two-week antibiotic course is given to respond to the bacteria. A further 2-week course is only given if the symptoms have improved but are not completely gone. If a child does not respond to the 4-week course, further investigations are carried out by physicians which include Full blood count, antibody levels, and vaccine responses to HiB [Haemophilus influenzae B], Tetanus, and Prevenar [pneumonia vaccines].9 In addition, a sweat test may be conducted wherein the amount of chloride in sweat is measured.10

Can PBB recur?

Yes, recurrences are common in children with PBB. It is estimated that around 40% of children affected by the disease will have one or more recurrences in the future.1 If this is the case, physicians treat with two weeks of antibiotics and perform further tests such as a cough swab or viral throat swab. If the wet and/or productive cough does not resolve following multiple courses of antibiotics, doctors may also choose to perform a bronchoscopy9 (a thin & illuminated tube known as a bronchoscope is inserted into the patient’s throat, windpipe, and finally the airways to have a clear look at the area).11

What are the complications of PBB?

The risk of complications in PBB usually arises with recurrent episodes which can lead to treatment difficulties and increase the risk of lung damage. As mentioned before, bacterial infections are one of the causes of the diseases. The prolonged presence of bacteria in the airways can cause lasting damage and even lead to Bronchiectasis which can further pave the way to a dangerous cycle of infection and airway obstruction.1

When to seek medical help

It is crucial to seek medical help as soon as possible to avoid disease progression and prevent extensive damage to the lungs. If you notice that your child has had a wet and sputum-based cough for the past few weeks, it is pertinent to make an appointment with your healthcare provider to rule out any causes/major issues and begin appropriate treatment if necessary. 


In a nutshell, Persistent bacterial bronchitis is a disease that has characteristics similar to many other chronic lung diseases and infections. Its predominant symptom is a wet and productive cough and it is usually caused due to infections but can also be brought about by airway deformities. Physicians usually diagnose it using three primary criteria (as mentioned above) and its treatment involves an antibiotic course of 2 weeks. Recurrence is often seen and depending on the severity of the recurrence, doctors may extend the antibiotic treatment and also perform other tests. Finally, it is crucial to remember that if your child is showing symptoms of the disease, it is best to get them checked up by your physician.


  1. American Thoracic Society PATIENT EDUCATION | INFORMATION SERIES CLIP AND COPY [Internet]. Available from:
  2. Gallucci, Marcella, et al. “When the Cough Does Not Improve: A Review on Protracted Bacterial Bronchitis in Children.” Frontiers, Frontiers, 1 Jan. 1AD,
  3. Chang AB, Marchant JM. Protracted bacterial bronchitis is a precursor for bronchiectasis in children: myth or maxim? Breathe. 2019 Sep;15(3):167–70.
  4. What is a URI? [Internet]. Available from:
  5. Martin MJ, Harrison TW. Causes of chronic productive cough: An approach to management. Respiratory Medicine. 2015 Sep;109(9):1105–13.
  6. Fernández Ventureira V, García Vera C. Protracted bacterial bronchitis: a condition to be considered in children. Anales de Pediatría (English Edition) [Internet]. 2020 Dec 1 [cited 2022 Jul 29];93(6):413–5. Available from:
  7. Tracheomalacia [Internet]. Available from:
  8. Gallucci M, Pedretti M, Giannetti A, di Palmo E, Bertelli L, Pession A, et al. When the Cough Does Not Improve: A Review on Protracted Bacterial Bronchitis in Children. Frontiers in Pediatrics. 2020 Aug 7;8.
  9. Kansra S. Diagnosis and Management of Children with Protracted Bacterial Bronchitis PBB. Scott A, editor. Sheffield’s Children NHS Foundation Trust. 2018 Jul;
  10. Sweat Test | Cystic Fibrosis Foundation [Internet]. Available from:
  11. Bronchoscopy [Internet]. 2019. Available from:
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Punyaslok Mishra Mishra

MB BCh BAO - Queen's University Belfast, Northern Ireland

Punyaslok is an emerging medical professional from Queen's University Belfast with a specialization in Medicine. He has showcased leadership as the President of the Asian Medical Students’ Association in Northern Ireland since August 2022. Besides, he contributes as a Peer Mentor and has recently undertaken a vital role as a Medical Writer Intern at Klarity, where he pens insightful articles for a health library, discussing topics from angina to the enzymes in papaya. Notably, Punyaslok's research on the potential of Mesenchymal Stem Cells in treating Anthracycline Induced Cardiomyopathy is affiliated with Queen's University, signifying his deep interest in advancing therapeutic measures in the medical realm.

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