PNEUMONIA  

  A  COMMON  AND  SERIOUS  INFECTION

A brilliant and famous doctor at the beginning of the 20th. century, Dr. William Osler, stated that “Pneumonia is the captain of the ships of death”. Today, well into the 21st. century, it still holds true, and despite the appearance of penicillin and subsequently all the array of new and wonderful antibiotics, it is the 6th. leading cause of deaths in the Unites States, with an incidence of 5 to 10 million acute new cases every year.  What are the reasons for this?  Before answering this question, I would like to give an insight into the natural defense mechanisms of the lung, which limits the access of germs and viruses to the distal parts of the airway.

The large surface area of the internal part of the nose is the first “trapping area” thanks to its anatomy and the mucus it produces, so that a lot of these inhaled microorganisms do not get any further. Then the large wind pipe through which we inhale air has 2 more mechanisms: millions of minute hairs which are called cilia are constantly brushing upwards at many beats per minute, so that whatever is caught on the surface with the production of mucus, the second mechanisms, is sent upwards, past the vocal cords, and once swallowed – usually unconsciously – it is destroyed in the acid medium of the stomach. The closure of the glottis when we swallow is a powerful ally, and when impaired, a very serious problem. A heavy contributor to this process is coughing, there being an enormous quantity of nerve ending  receptors along the bronchial tubes which, when irritated, produce the cough. Researchers into this say that when we cough, the air is moving upwards at 700 to 800 kilometres an hour, all generated by one single and massive muscular effort, which coordinates the abdominal and chest muscles, plus the diaphragm. In this way, a larger production of mucus gets to the mouth and is spat out as phlegm.   If that were not enough, lined up along the bronchial tubes practically up to the minute spaces called alveoli, where gas exchange with the blood takes place, are special cells that besides producing antibodies, are prepared also to engulf the inhaled offending particles including bacteria and viruses.  Furthermore, many of the circulating antibodies and white cells in the blood can be immediately recruited to any area of the lung where microorganisms have accessed.

Thus, there are many ways that bacteria can get to the small alveolar sacs of the lung, after being inhaled:
  • A very large quantity of germs that overwhelm the defensive army, either inhaled directly, or from the mucus in the upper airways where germs can be present without symptoms and aspirated (inhaled) during sleep;
  • An impaired closure reflex of the glottis, especially in very elderly persons;
  • Anything that harms the ciliary process and the production of mucus;
  • Illnesses, or their treatments, which breakdown the defensive cell mechanisms or the effectiveness of the circulating antibodies;
  • Breathing in whilst lying down during an episode of vomiting;
  • Spread from an infection elsewhere in the body.
Because of the different circumstances pertaining to each person, and the environment where the infection begins, a first very important step in to classify it as Community Acquired Pneumonia (CAP) or as Hospital Acquired Pneumonia (HAP).  This is a crucial step, as the bacteria and viruses which produce them are very different, as is the severity of the infection.  Another important distinction must be done in the Community Acquired variety is if you are under or over the age of 60, as the latter implies a bigger risk of serious illness, and the treatment is tailored accordingly.

There are a variety of symptoms which are very suggestive of pneumonia, though not necessarily  present in everybody who contracts the illness: a sudden onset of high fever, with a cough, one sided chest pain, shortness of breath and varying amounts of nasty phlegm, sometimes bloody.  Sometimes these come on after a flu-like condition. Most of the time the doctor can pick up signs on examining the patient, which are corroborated by a chest X-ray. 

Unfortunately, we do not recover the germ that causes the pneumonia in more than half of all cases: either there is no phlegm to analyze, or it is contaminated with germs of the mouth and the nose, or the patient can’t produce it, and less than 20% have the germ circulating in blood. In very severe cases when it is vital to know the offending germ, a sterile tube is put down via the mouth or the nose to the involved area of the lung, and secretions are sucked out and analyzed: this is called fiberoptic bronchoscopy. For all these reasons, the doctor must be aware of the clinical setting of each patient, his age, the environment, the severity of infection, so as to decide what antibiotic to use to begin treatment. It is well established that the sooner treatment is started, the better the chance for recovery.

Most of the pneumonias developed in the Community can be treated at home, and knowing that in most Western  countries including Argentina the most common offender is a bacteria called Streptococcus Pneumoniae, treatment with the correct antibiotic can be started right away.  Other causes have to be ruled out, such as the germ which are carried by parrots, parakeets and other fowl, the germ that causes meningitis, a microorganism which grows in water coolers and is known as Legionnaires Disease, and many others, but more uncommon. 

If you are over 60, if you have other chronic illnesses of the heart or the lungs, or if the fever continues despite treatment, or if the blood pressure is very low, the best approach is for you to be admitted to Hospital for a few days. Very severe pneumonias are treated in the Intensive Care Unit. A common complication (which sometimes is the first sign of pneumonia) is the appearance of chest pain on one side with shortness of breath, which means that liquid and pus are accumulating in the pleural space next to the segment of the lung developing pneumonia: this has to be solved in Hospital by surgical drainage of the liquid with the placement of a chest tube. 

A vaccine has been developed against the Streptococcus Pneumoniae, and should be applied to everybody over the age of 65, and people of all ages with chronic bronchial, lung or heart problems. The vaccine  is effective in lessening the severity of the pneumonia, if not in preventing it, and should be repeated every 5 years.  No form of prevention has been found for all the other microorganisms that can be involved, but together they account for less than 50 % of the pneumonias.  A good recommendation is to have the influenza vaccine (flu) every year.

The Hospital Acquired Pneumonias (HAP), as it’s name suggests, develop in people who are in Hospital for other causes. After 2 or 3 days of going in, the bacteria which normally live in the mouth and in the nose change, and become more aggressive or more resistant to antibiotics given for other reasons, and any of the conditions listed initially favor the appearance of HAP. The Infectious Disease team implements programs to diminish the risk of this happening, and they have nurses devoted exclusively to supervise these actions, and to pick up the appearance of this complication as early as possible. Whilst different aggressive diagnostic testing is done to recover the germ causing the pneumonia, a combination of antibiotics are begun to cover for most of the likely possibilities.  

Though frequently it is necessary, the shorter the time one spends in the Hospital the better!  

Dr. John. Emery
July, 2008