When we think of pneumonia, we see it as a complicated and dangerous infection caused by bugs ‘in the air’. But there are a number of disparate, but common, medications that can lead to pneumonia, sometimes fatally. Going into hospital can cause it, too.
What is pneumonia? It’s an inflammation of the lungs that we tend to hear little of these days as it’s lumped together with things like tuberculosis and rickets - supposedly problems of yesteryear.
But, in fact, pneumonia is on the increase and, in the UK, the number of deaths due to the disease has almost doubled in less than a decade.
Having pneumonia has been described as being like having a cold or the flu, but far more intense. The breathing problems caused by a cold are uncomfortable and may even be incapacitating, but they won’t kill you and will normally fade away on their own. Pneumonia, on the other hand, can linger, worsen and, finally, interfere with breathing to the point of being fatal.
Most pneumonia occurs in the winter, typically striking the very young or the over-65s (JAMA, 1995; 274: 134-41). Up to 4 per cent of children in Europe and the US catch pneumonia (Am Fam Physician, 2004; 70: 899-908). It can be brought on by nearly anything that infects the lungs - mainly bacteria, but also viruses, parasites and fungal spores.
Potentially fatal illness
Pneumonia often arrives a few days after an apparently benign cold or sore throat. However, what makes it so serious compared with a cold is that it causes a build-up of fluid in the lungs, thus clogging up the tiny air sacs (alveoli) in the lungs where oxygen is taken from the air and transferred to the bloodstream.
So, it’s a lack of oxygen, rather than the infection itself, that causes the high death rate. An additional factor is that as much as 80 per cent of pneumonia-causing bacteria have become resistant to antibiotics (Semin Respir Infect, 2000; 15: 195-207).
Doctors have traditionally classified pneumonia into two types, depending on how you caught it. Until the advent of modern medicine, the most common type was the so-called ‘community-acquired’ pneumonia (CAP) - something caught from other people.
However, nowadays, running a close second is what’s admitted to be ‘hospital-acquired pneumonia’ (HAP), seen almost exclusively in intensive care units. Up to half of all ICU patients contract pneumonia, among whom 27-50 per cent actually die of the condition (Infect Dis Clin North Am, 1998; 12: 761-79).
Why should hospital ICUs be so hazardous? The major reason is believed to be because ICU patients are often ‘ventilated’ to help them breathe. This involves forcing an airway tube down the throat, thus bypassing the lungs’ primary physical defence against infection - the cough reflex. Bacteria can then enter the lungs unimpeded. Hospital bacteria can be extremely virulent, particularly the ‘gram-negative’ variety which, because they are not found outside of hospitals, people will have no resistance to. They also tend to be resistant to antibiotics.
HAP is widely acknowledged to be a serious, growing problem, exacerbated by the fact that it’s difficult to diagnose (Crit Care Med, 2000; 28: 2799-804). It’s also a classic example of an iatrogenic (doctor-caused) condition, but it’s not the only one for pneumonia.
In addition to CAP and HAP, there’s now a third one - DAP, drug-acquired pneumonia. So far, at least a half-dozen types of medications have been found to cause pneumonia-like lung inflammation. Last month (WDDTY vol 15 no 10), we featured the latest research showing that everyday antiulcer drugs such as Tagamet, Zantac and Losec have been responsible for a doubling of pneumonia cases, particularly among older patients (JAMA, 2004; 292: 1955-60).