PSEUDOMONA AERUGINOSA
This bacteria is commonly involved in infections acquired while in the hospital (known scientifically as nosocomial infections – after the Greek word for hospital).
It is not uncommon to find it involved in infections of:
the blood
bones
joints
lungs
the urinary tract
the abdomen (peritonitis).
It may be introduced to the body leading to infection by means of a catheter, or during transplant surgery. It has displayed resistance to many forms of antibiotics, but at present remains treatable.
ACINETOBACTER SPP
This organism, which normally lives on the skin, can (usually in hospital settings) opportunistically become involved (perhaps after catheter use) in infections of the:
urinary tract
the lining of the brain – meningitis
and in peritonitis.
It has become widely resistant to antibiotics which previously controlled it.
MYCOBACTERIUM TUBERCULOSIS
Tuberculosis was until recently under control, at least in developed Western countries. However it has re-emerged as a major threat, and Mycobacterium tuberculosis can now be found in forms which are almost untreatable.
One of the major reasons for the development of resistance has been the tendency for some patients to fail to complete their courses of antibiotic treatment, one of the major factors that offers bacteria a chance to evolve defenses against a drug which is trying to kill them. It is as though a defending army were to show potential invaders how it proposed to defend itself and then decided to take a vacation, so allowing the invader time to work out new ways of overcoming it.
Among the most important background reasons for the emergence of multiple drug-resistant strains of Mycobacterium tuberculosis are thought to be:
failure of patients to complete courses of treatment – leading to mutant, resistant strains
deteriorating public health services due to economic constraints
poor training of health care workers in diagnosing and treating TB
delays in obtaining laboratory test results
use of only single-drug approaches to treat the infection (see below)
a dramatic increase in the numbers of susceptible people, often involving those who are impoverished and therefore malnourished, and/or homeless, and/or HIV positive and/or drug abusers
increasing migration into Western urban settings of people from areas where TB is endemic.
Many of these factors are beyond easy solution, and are political and economic in origin rather than medical. In other words, if everyone were well housed, well fed, well cared for and did not engage in practices which damage their immune systems, TB would vanish.
For successful care of TB today, there needs to he:
sound nutrition and hygiene
supervision which ensures that courses of antibiotic treatment are completed
the correct selection of a combination of antibiotic medications.
A treatment approach which involves using a combination of antibiotic drugs against the infection has been found to present the best option, since this offers multiple ways of killing or deactivating the invader.
When only single drugs are used, even if the course is followed through, Mycobacterium tuberculosis can respond with dramatically rapid genetic modifications in order to protect itself.
The number of cases in which treatment fails completely in dealing with TB is still relatively small, however when multiple drug-resistant tuberculosis (MDR-TB) does occur it is usually fatal, especially when this occurs in someone whose immune system is already compromised, for instance a person with an existing HIV infection or who is severely malnourished, such as a persistent drug abuser.
Sadly, hospital outbreaks of MDR-TB are increasing. Some of the reasons for this have been mentioned, but a summary is offered on pages of other reasons why many bacteria have become immune to attack by antibiotics.
This is the cast – the good, the bad, and the frightening – we now need to become familiar with the way medicine tries to control them.
3: The Story So Far: A Brief History of Antibiotic Use
Before looking at antibiotics themselves, we should briefly examine antibacterial approaches, some of which are still in use, which preceded the discovery of antibiotics.
Before 1935 there were few successful medical methods for treating infections apart from procedures which went back hundreds of years, such as the use of an extract of cinchona bark for the treatment of malaria (from which quinine was eventually derived) and the use of ipecacuanha for some forms of dysentery.
During the early 20th century a few medications were developed in Germany for treatment of parasitic infections, but there were no antibacterial medications as such until the discovery of sulfur drugs, which were able to save lives in conditions which had previously been virtually untreatable.
The Sulfur Drugs
In 1935 it was announced that a drug had been developed, in Germany, of a sulfur derivative which could be used to treat commonly fatal streptococcal infections such as puerperal fever.
In the early 1930s over 1,000 young women were dying every year, in the UK, after childbirth because of infection of the bloodstream, from puerperal fever. Well over 100 out of every 100,000 births