Sir William Osler, one of the founding fathers of John Hopkin’s Hospital, is frequently described by scholars as “the Father of Modern Medicine” and is quite known in the scientific and medical field. Among the traits that this celebrated physician is famous for, one of them stood out, his penchant for dark humor.
In the third edition of his textbook “The Principles and Practice of Medicine” he called Pneumonia “The old Man’s Friend” with a rationale that it allowed elderly individuals a quick, comparatively painless death: “Taken off by it in an acute, short, not often painful illness, the old man escapes those cold gradations of decay”. Coincidentally, he himself died of Pneumonia.
People 100 years ago had a fatalistic view of pneumonia, but that has changed. Now there are vaccines and drugs that could prevent and cure it, despite that, according to the Lancet, It remains a major cause of death among all age groups resulting in 4 million deaths (7% of the world’s total death) yearly. A world health organization fact sheet states that Pneumonia accounts for 15% of all deaths of children under 5 years old, killing 808 694 children in 2017 alone.
One of COVID-19’s complications is Pneumonia, but Pneumonia is not only caused by viral pathogens. It may be caused by bacteria, fungi and in some cases, non-infectious causes (idiopathic interstitial pneumonia). Let’s have a look at its Basics.
PNEUMONIA
The Centers for Disease Control states that Pneumonia is an infection of the lungs that can cause mild to severe illness in people of all ages.
Pneumonia is basically an infection of the lungs caused by microbes. The inflammation that this infection causes usually brings in water into the lungs, and it makes beathing difficult. The lungs are made up of small sacs called alveoli, which fill with air when a healthy person breathes. When an individual has pneumonia, the alveoli are filled with pus and fluid, which makes breathing painful and limits oxygen intake.
Normally we are not only breathing in air, but all sorts of particles such as dust and microorganisms. Coughing and sneezing are actually some of our protective mechanisms to push these foreign particles out. Another is a mucociliary escalator, which is a lining of hairlike cells in the surfaces of our mucous membranes that sweep up pathogens. The rest of the pathogens that manage to go deeper into the lung tissue are met with our immune defenses, such as alveolar macrophages – even then pathogens may still succeed in colonizing the alveoli and bronchioles of the lungs causing pneumonia.
How it fills with pus and fluid is through the succeeding inflammatory response. White blood cells and proteins get caught up in the mix, sometimes a capillary will get destroyed and blood joins in.
CAUSES and CHARACTERIZATIONS of PNEUMONIA
Pneumonia is usually classified as Community Acquired Pneumonia and Hospital Acquired Pneumonia, the former’s only difference is that it was not acquired in the hospital setting.
Meanwhile a lot of pathogens have the ability to cause pneumonia, and it isn’t just COVID-19. The most common cause of viral pneumonia is the influenza virus (the flu) while bacterial Pneumonia’s most common culprit is Streptococcus pneumoniae. There are actually a group of bacteria further differentiated from the common ones, for example, Mycoplasma Pneumoniae and Chlamydophyla Pneumoniae are bacteria with no cell wall, thus the usual antibiotics used to kill pathogens through the mechanism of dissolving their cell walls do nothing against them – and they cause vague symptoms like fatigue instead of the usual dramatic course of your typical pneumonia. – These group are aptly named Atypical Pneumonia.
Pneumonia caused by Fungi (Fungal Pneumonia) are uncommon, and usually affects people of older age and immunocompromised.
A common threat in the treatment of Pneumonia are Bacteria that have acquired resistance. These are usually the pathogens from Hospital Acquired Pneumonia. The dreaded MRSA – or Methicillin-resistant Staphylococcus aureus which is an evolved / mutated and genetically distinct form of Staphylococcus aureus. Physicians dread it if a patient tests positive for this microbial infection especially in their Pneumonia cases because this is very hard to treat.
A subset of Hospital Acquired Pneumonia is Ventilator associated pneumonia, and may be the pneumonia seen in severe cases of COVID-19. This usually happens when a patient is attached with an endotracheal tube. There are cases where-in a mix of proteins, sugars and bacteria clump up and become what’s called a biofilm in the surface of these ventilators. Since a patient with a ventilator can’t cough, and is obviously pretty sick already, microbes can move from the tube into the lung directly causing pneumonia.
Now inhaling viruses and bacteria aren’t the only way pneumonia develops – there’s this special type called Aspiration Pneumonia, which typically happens in infants. Basically this is when a relatively large amount of foreign material from the stomach or mouth enters the lungs – perhaps a food particle. Usually our gag and cough reflexes would pull that piece of burger out, but in the unfortunate event that these reflexes are compromised (due to brain damage, drugs or alcohol) the burger piece may be stuck in the airways. Now that’s not exactly sterile, and may develop an infection.
Another way to characterize a Pneumonia is the area in the lung it has infected.
A bronchopneumonia implies that the infection is broad and may be throughout the lungs. An Interstital Pneumonia (this is commonly an atypical type of pneumonia) implies that the infection may be broad / or just a certain part of the lung’s lobe but is situated just outside the alveoli. Meanwhile a Lobar Pneumonia implies that the infection strictly occupies a lobe or set of lobes of the lung, sometimes with full consolidation of fluid.
Lobar Pneumonia is interesting because it has its stages, which may be determined and separated in days. The first two days is congestion, in which the blood vessels and alveoli are filled with fluid. The next two days is red hepatization where exudates such as red blood cells, neutrophils and fibrin fill airspaces and make them more solid – the name comes from the appearance of the lung which closely resembles the liver. Around days five to seven, there is gray hepatization in which the red blood cells from the exudate starts to break down and the area is turning gray in color. The last stage is resolution or Recovery in which the exudate is digested by enzymatic activity, and cleared by macrophages or by the cough mechanism and expelled.
SIGNS and SYMPTOMS of PNEUMONIA
Pneumonia may cause productive cough that may be bloody, fever accompanied by shaking chills, shortness of breath, sharp or stabbing chest pain during deep breaths, and an increased rate of breathing.
Diagnosing Pneumonia is usually with a combination of physical signs on the patient as well as a thorough physical examination by the physician and x-rays.
PREVENTION of PNEUMONIA
Treating Pneumonia depends on the type, characteristics and most especially the causative agent. Treatments also differ based on the severity of pneumonia and the age group.
According to the World Health Organization it is believed that, if appropriate preventive measures were instituted globally, mortality among children could be reduced by 400,000; and, if proper treatment were universally available, childhood deaths could be decreased by another 600,000.
The Center for Disease Control and Prevention recommends yearly influenza vaccination for every person 6 months and older. A 2007 study published on the National Institute of Health stated that immunizing health care workers decreases the risk of viral pneumonia among them.
The widely available Pneumococcal conjugate vaccine (PCV) is a pneumococcal vaccine and a conjugate vaccine used to protect infants, young children, and adults against disease caused by the bacterium Streptococcus pneumonia.
The World Health Organization recommends the use of the conjugate vaccine in routine immunizations given to children, while The CDC recommends that young children and adults over the age of 65 receive the pneumococcal vaccine, as well as older children or younger adults who have an increased risk of getting pneumococcal disease.
Interestingly Vaccination for Chicken Pox (Varicella), Measles and Pertussis have a protective effect against Pneumonia.
