A respiratory tract infection (RTI) is defined as any infectious disease involving the upper or lower respiratory tract.
It can be accordingly classified as either an upper respiratory tract infection (URTI) or a lower respiratory tract infection (LRTI).
The upper respiratory tract consists of the nose, sinuses, pharynx and larynx.
Examples of URTIs are pharyngitis, acute sinusitis, acute epiglottitis and diphtheria.
The lower respiratory tract consists of the trachea, bronchial tree and lungs.
Examples of LRTIs are acute bronchitis, whooping cough (pertussis), pneumonia and pulmonary tuberculosis (TB).
LRTIs are generally more severe than URTIs, and are the leading cause of death among all infectious diseases.
Although bacteria, viruses and fungi can all cause RTIs, only those caused by bacteria are highlighted here.
Pharyngitis is commonly known as a sore throat.
It is inflammation of pharyngeal mucosa and submucosa primarily involved in pharyngeal lymphoid tissue.
While mostly caused by viruses, it can also result from infection by bacteria like Streptococcus pyogenes, Corynebacterium diphtheriae, Borrelia vincentii, Neisseria gonorrhoeae, Haemophilus influenzae and Staphylococcus aureus.
It can affect both children and adults, and usually comes with a fever and pain in the throat.
Other symptoms may include a runny nose, cough, headache, a hoarse voice, tender enlargement of the tonsils and cervical lymphadenopathy.
Symptoms usually last three to five days.
It is easily treated with antibiotics.
Acute sinusitis is a short-term inflammation of the sinuses, most often accompanied by a sinus infection.
It is also known as rhinosinusitis as the swelling almost always involves both nasal (rhino is the Latin word for nose) tissue and sinus tissue.
Acute sinusitis causes the spaces inside the nose (sinuses) to become inflamed and swollen.
This interferes with the drainage of mucus and causes it to build up.
A common cold or allergies often cause acute sinusitis.
It can also be caused by a bacterial or fungal infection that causes the sinuses to swell and become blocked.
Common symptoms include thick yellow or greenish discharge from the nose; nasal obstruction or congestion that causes difficulty in breathing; and pain, tenderness, swelling and pressure around the eyes, cheeks, nose or forehead that worsens when bending over.
The cheekbone (maxillary) sinuses are the most commonly affected.
Antibiotics are usually not needed to treat acute sinusitis.
Even if the cause is bacterial, it may clear up without treatment.
Antibiotics are only recommended if the symptoms last more than a week.
Epiglottitis is inflammation of the epiglottis.
It is a severe throat infection that obstructs the airway.
Epiglottitis is typically due to a bacterial infection of the epiglottis.
Historically, it was most often caused by H. influenzae type B, but with immunisation, this is no longer the case.
Now, the bacteria most typically involved in this condition are Streptococcus pneumoniae, S. pyogenes or S. aureus.
Common symptoms include high fever, severe sore throat, difficulty swallowing, drooling and stridor (a noisy or high-pitched sound while breathing).
It is treated with antibiotics.
Diphtheria is a severe bacterial infection that affects the mucous membranes of the throat and nose.
It can lead to difficulty in breathing, heart failure, paralysis, and even death.
It is caused by the toxin-producing bacterium C. diphtheriae, and is spread by direct contact with a patient or carrier.
Symptoms include fever of 38°C or above, chills, fatigue, bluish skin (cyanosis), sore throat, hoarseness, cough, headache, difficulty and pain in swallowing, difficulty in breathing, rapid breathing, foul- smelling bloodstained nasal discharge and lymphadenopathy.
It can also be accompanied by cardiac arrhythmias, myocarditis, and cranial and peripheral nerve palsies.
Diphtheria is treated with antibiotics, and can be prevented with vaccination, which has made it rare.
Whooping cough, also known as pertussis, is a bacterial infection that gets into the nose and throat.
It is a highly contagious RTI caused by the bacterium Bordetella pertussis, and is a severe disease of childhood.
In many people, it is marked by a severe hacking cough, followed by a high-pitched intake of breath that sounds like “whoop”.
It is an airborne disease that spreads quickly through the droplets expelled by the coughs and sneezes of an infected person.
Initial symptoms are similar to those of the common cold with a runny nose, fever and mild cough.
But these are then followed by weeks of severe coughing fits with the “whoop” breathing sound.
People may cough so hard that they vomit, break their ribs or become very tired from the effort.
The coughing may last for ten or more weeks, hence the phrase “100-day cough”.
Treatment includes supportive care, and antibiotics are helpful if started within three weeks of the initial symptoms.
Whooping cough can be prevented by vaccination.
Pneumonia is inflammation of the alveoli (air sacs) in one or both lungs.
The alveoli may fill up with fluid or pus, and other liquids.
Pneumonia can range in seriousness from mild to life-threatening.
It is most serious for infants and young children, adults older than 65, and those with health problems or weakened immune systems.
There are a few types of pneumonia, i.e. community-acquired pneumonia, atypical pneumonia, hospital-acquired pneumonia and aspiration pneumonia.
Community-acquired pneumonia is the most common type and can be caused by S. pneumoniae, H. influenzae, Klebsiella pneumoniae, Mycoplasma pneumoniae, Chlamydophila pneumoniae and Legionella pneumophila.
Atypical pneumonia is caused by M. pneumoniae, C. pneumoniae, Chlamydia psittaci, Coxiella burnettii and L. pneumophila.
Hospital-acquired pneumonia is caused by Enterobacteriaceae species and Pseudomonas aeruginosa.
Mixed bacteria cause aspiration pneumonia, where they enter the lungs via inhalation of aerosolised material or aspiration of the normal flora of the upper respiratory tract and bloodstream.
As a wide range of microorganisms cause pneumonia, the symptoms cannot be distinguished from the cause.
They can vary from mild to severe, depending on the type of bacteria causing the infection, and the patient’s age and overall health.
They include fever, cough with sputum, shortness of breath, difficulty and pain on breathing, and chest pain that may be pleuritic.
Newborns and infants may not show any sign of pneumonia.
But if they do, the symptoms are usually vomiting; fever; cough; restlessness or tiredness and listlessness; or difficulty in breathing and eating.
Pneumonia is treated with antibiotics, and immunisation is available against a few of the bacterium that cause it.
Pulmonary TB is a contagious and slowly progressive bacterial infection of the lungs.
It is mainly caused by the bacterium Mycobacterium tuberculosis.
It is the most common infectious cause of death worldwide and the leading cause of death among people with HIV/AIDS.
Most infections show no symptoms, in which case, it is known as latent TB.
People with latent TB do not spread the disease.
About 10% of latent infections progress to active disease, which, if left untreated, kills about half of those affected.
Active infection occurs more often in people with HIV/AIDS and in those who smoke.
TB is spread through the respiratory droplets released into the air when people with active TB in their lungs cough, spit, speak or sneeze.
Symptoms include chest pain, coughing up blood, and a productive, prolonged cough for more than three weeks.
Other symptoms include fever, chills, night sweats, loss of appetite, weight loss, pallor, and often becoming fatigued very quickly.
TB is treated with multiple antibiotics.
The course of drug therapy usually lasts for six to nine months.
It can be prevented with vaccination.
Legionnaires’ disease is a severe, potentially deadly lung infection.
It is an extreme form of pneumonia caused by a bacterium known as L. pneumophila.
Most people catch Legionnaires’ disease by inhaling soil or contaminated aerosols generated from hot water taps or showers.
Symptoms include a cough, shortness of breath, high fever, muscle pains and headaches.
Nausea, vomiting and diarrhoea may also occur.
Multi-organ disease involving the gastrointestinal tract, central nervous system, liver and kidneys is common.
It is treated with antibiotics.
Prevention
RTIs are prevalent and it is necessary to protect ourselves from getting these infections.
The aim of prevention is to reduce the frequency of RTIs by interrupting their transmission, while the aim of management is to reduce the duration of infection and prevent complications.
Some RTIs caused by bacteria can be prevented by vaccines, although we do not have vaccines for many infections.
Here are other preventive measures we can follow:
- Avoid direct contact with an RTI patient.
- Wash your hands frequently with soap and water, or sanitise them with an alcohol hand rub.
- Work with a doctor to keep your allergies under control.
- Avoid cigarette smoke and polluted air.
- Wear a face mask in a crowded place.
- Keep your immune system strong.
- Maintain personal hygiene.
Associate Professor Dr Mohammad Nazmul Hasan Maziz is a medical microbiologist and deputy dean of the Perdana University Graduate School of Medicine. This article is courtesy of Perdana University, which is celebrating their 10th anniversary this year. For more information, email starhealth@thestar.com.my. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.
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