Acute bronchitis is an inflammation

Inflammation

Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...

 of the large bronchi

Bronchus

A bronchus is a passage of airway in the respiratory tract that conducts air into the lungs. The bronchus branches into smaller tubes, which in turn become bronchioles....

 (medium-size airways) in the lung

Lung

The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...

s that is usually caused by virus

Virus

A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

es or bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 and may last several days or weeks. Characteristic symptoms include cough

Cough

A cough is a sudden and often repetitively occurring reflex which helps to clear the large breathing passages from secretions, irritants, foreign particles and microbes...

, sputum

Sputum

Sputum is mucus that is coughed up from the lower airways. It is usually used for microbiological investigations of respiratory infections....

 (phlegm) production, and shortness of breath and wheezing related to the obstruction of the inflamed airways. Diagnosis is by clinical examination and sometimes microbiological

Microbiology

Microbiology is the study of microorganisms, which are defined as any microscopic organism that comprises either a single cell , cell clusters or no cell at all . This includes eukaryotes, such as fungi and protists, and prokaryotes...

 examination of the phlegm. Treatment for acute bronchitis is typically symptomatic. As viruses cause most cases of acute bronchitis, antibiotic

Antibiotic

An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...

s should not be used unless microscopic examination of gram-stained sputum reveals large numbers of bacteria.

Cause/etiology

Acute bronchitis can be caused by contagious pathogen

Pathogen

A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...

s. In about half of instances of acute bronchitis, a bacterial or viral pathogen is identified. Typical viruses include respiratory syncytial virus

Human respiratory syncytial virus

Human respiratory syncytial virus is a virus that causes respiratory tract infections. It is the major cause of lower respiratory tract infections and hospital visits during infancy and childhood. A prophylactic medication exists for preterm birth infants and infants with a congenital heart...

, rhinovirus

Rhinovirus

Human rhinoviruses are the most common viral infective agents in humans and are the predominant cause of the common cold. Rhinovirus infection proliferates in temperatures between 33–35 °C , and this may be why it occurs primarily in the nose...

, influenza

Influenza

Influenza, commonly referred to as the flu, is an infectious disease caused by RNA viruses of the family Orthomyxoviridae , that affects birds and mammals...

, and others.

• Damage caused by irritation of the airways leads to inflammation and leads to neutrophils infiltrating the lung tissue.
• Mucosal hypersecretion is promoted by a substance released by neutrophils
  Neutrophil granulocyte
  Neutrophil granulocytes are the most abundant type of white blood cells in mammals and form an essential part of the innate immune system. They are generally referred to as either neutrophils or polymorphonuclear neutrophils , and are subdivided into segmented neutrophils and banded neutrophils...
  
  .
• Further obstruction to the airways is caused by more goblet cells in the small airways. This is typical of chronic bronchitis.
• Although infection is not the reason or cause of chronic bronchitis, it is seen to aid in sustaining the bronchitis.

Signs and symptoms

Bronchitis may be indicated by an expectorating cough

Cough

A cough is a sudden and often repetitively occurring reflex which helps to clear the large breathing passages from secretions, irritants, foreign particles and microbes...

, shortness of breath (dyspnea

Dyspnea

Dyspnea , shortness of breath , or air hunger, is the subjective symptom of breathlessness.It is a normal symptom of heavy exertion but becomes pathological if it occurs in unexpected situations...

), and wheezing. On occasion, chest pain

Chest pain

Chest pain may be a symptom of a number of serious conditions and is generally considered a medical emergency. Even though it may be determined that the pain is non-cardiac in origin, this is often a diagnosis of exclusion made after ruling out more serious causes of the pain.-Differential...

s, fever

Fever

Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...

, and fatigue

Fatigue (physical)

Fatigue is a state of awareness describing a range of afflictions, usually associated with physical and/or mental weakness, though varying from a general state of lethargy to a specific work-induced burning sensation within one's muscles...

 or malaise

Malaise

Malaise is a feeling of general discomfort or uneasiness, of being "out of sorts", often the first indication of an infection or other disease. Malaise is often defined in medicinal research as a "general feeling of being unwell"...

 may also occur. In addition, bronchitis caused by Adenoviridae

Adenoviridae

Adenoviruses are medium-sized , nonenveloped icosahedral viruses composed of a nucleocapsid and a double-stranded linear DNA genome...

 may cause systemic and gastrointestinal symptoms as well. However, the coughs due to bronchitis can continue for up to three weeks or more even after all other symptoms have subsided.

Diagnosis

A physical examination

Physical examination

Physical examination or clinical examination is the process by which a doctor investigates the body of a patient for signs of disease. It generally follows the taking of the medical history — an account of the symptoms as experienced by the patient...

 will often reveal decreased intensity of breath sounds, wheezing, rhonchi

Rhonchi

Rhonchi is the coarse rattling sound somewhat like snoring, usually caused by secretion in bronchial airways. Rhonchi is the plural form of the singular word rhonchus.-Description:...

, and prolonged expiration

Exhalation

Exhalation is the movement of air out of the bronchial tubes, through the airways, to the external environment during breathing....

. Most doctors rely on the presence of a persistent dry or wet cough as evidence of bronchitis.

A variety of tests may be performed in patients presenting with cough and shortness of breath:

• A chest X-ray
  Chest X-ray
  In medicine, a chest radiograph, commonly called a chest X-ray , is a projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures...
  
   that reveals hyperinflation; collapse and consolidation of lung areas would support a diagnosis of pneumonia
  Pneumonia
  Pneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...
  
  . Some conditions that predispose to bronchitis may be indicated by chest radiography.
• A sputum sample showing neutrophil granulocyte
  Neutrophil granulocyte
  Neutrophil granulocytes are the most abundant type of white blood cells in mammals and form an essential part of the innate immune system. They are generally referred to as either neutrophils or polymorphonuclear neutrophils , and are subdivided into segmented neutrophils and banded neutrophils...
  
  s (inflammatory white blood cells) and culture
  Microbiological culture
  A microbiological culture, or microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture media under controlled laboratory conditions. Microbial cultures are used to determine the type of organism, its abundance in the sample being tested,...
  
   showing that has pathogenic microorganisms such as Streptococcus species
  Streptococcus
  Streptococcus is a genus of spherical Gram-positive bacteria belonging to the phylum Firmicutes and the lactic acid bacteria group. Cellular division occurs along a single axis in these bacteria, and thus they grow in chains or pairs, hence the name — from Greek στρεπτος streptos, meaning...
  
  
• A blood test
  Blood test
  A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a needle, or via fingerprick....
  
   would indicate inflammation (as indicated by a raised white blood cell
  White blood cell
  White blood cells, or leukocytes , are cells of the immune system involved in defending the body against both infectious disease and foreign materials. Five different and diverse types of leukocytes exist, but they are all produced and derived from a multipotent cell in the bone marrow known as a...
  
   count and elevated C-reactive protein
  C-reactive protein
  C-reactive protein is a protein found in the blood, the levels of which rise in response to inflammation...
  
  ).

Antibiotics

Only about 5-10% of bronchitis cases are caused by a bacterial infection. Most cases of bronchitis are caused by a viral infection and are "self-limited" and resolve themselves in a few weeks. Acute bronchitis should not be treated with antibiotics unless microscopic examination of the sputum reveals large numbers of bacteria. Treating non-bacterial illnesses with antibiotics leads to the promotion of antibiotic-resistant bacteria, which increase morbidity and mortality.

Smoking cessation

Many physicians recommend that, to help the bronchial tree heal faster and not make bronchitis worse, smokers

Tobacco smoking

Tobacco smoking is the practice where tobacco is burned and the resulting smoke is inhaled. The practice may have begun as early as 5000–3000 BCE. Tobacco was introduced to Eurasia in the late 16th century where it followed common trade routes...

 should quit smoking completely in order to allow their lungs to recover from the layer of tar that builds up over time.

Antihistamines

Using over-the-counter antihistamine

Antihistamine

An H1 antagonist is a histamine antagonist of the H1 receptor that serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions...

s may be harmful in the self-treatment of bronchitis.

An effect of antihistamines is to thicken mucus secretions. Expelling infected mucus via coughing can be beneficial in recovering from bronchitis. Expulsion of the mucus may be hindered if it is thickened. Antihistamines can help bacteria to persist and multiply in the lungs by increasing its residence time

Residence time

Residence time is the average amount of time that a particle spends in a particular system. This measurement varies directly with the amount of substance that is present in the system....

 in a warm, moist environment of thickened mucus.

Using antihistamines along with an expectorant cough syrup may be doubly harmful, encouraging the production of mucus and then thickening that which is produced. Using an expectorant cough syrup alone might be useful in flushing bacteria from the lungs. Using an antihistamine along with it works against the intention of using the expectorant.

Prognosis

Acute bronchitis usually lasts a few days or weeks. It may accompany or closely follow a cold or the flu, or may occur on its own. Bronchitis usually begins with a dry cough, including waking the sufferer at night. After a few days, it progresses to a wetter or productive cough, which may be accompanied by fever, fatigue, and headache. The fever, fatigue, and malaise may last only a few days; but the wet cough may last up to several weeks.

Should the cough last longer than a month, some doctors may issue a referral to an otorhinolaryngologist (ear, nose and throat doctor) to see if a condition other than bronchitis is causing the irritation. It is possible that having irritated bronchial tubes for as long as a few months may inspire asthmatic conditions in some patients.

In addition, if one starts coughing mucus tinged with blood, one should see a doctor. In rare cases, doctors may conduct tests to see whether the cause is a serious condition such as tuberculosis

Tuberculosis

Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...

 or lung cancer

Lung cancer

Lung cancer is a disease characterized by uncontrolled cell growth in tissues of the lung. If left untreated, this growth can spread beyond the lung in a process called metastasis into nearby tissue and, eventually, into other parts of the body. Most cancers that start in lung, known as primary...

.

Prevention

In 1985, University of Newcastle, Australia

University of Newcastle, Australia

The University of Newcastle is an Australian public university that was established in 1965. The University's main and largest campus is located in Callaghan, a suburb of Newcastle in New South Wales...

 Professor Robert Clancy

Professor Robert Clancy

Professor Robert Clancy developed the vaccine Broncostat at the University of Newcastle in 1985. Broncostat reduces attacks of acute bronchitis to a degree of 90%.Broncostat was commercialised in 1989 by Rhone-Poulenc Rorer Australia Pty. Ltd.- References :...

 developed an oral vaccine for Haemophilus influenza. This vaccine was commercialised four years later.

External links

• Acute Bronchitis FamilyDoctor.org (American Academy of Family Physicians)