Molecular Method Quickly Identifies Antibiotic-Resistant Acinetobacter

Acinetobacter baumannii, a bacterium widely found on our skin and in the environment, has now become a major threat in hospitals where it can cause serious infections, such as pneumonia in severely ill patients. The new types Acinetobacter are resistant to nearly all antibiotics and three resistant strains are currently circulating in the United Kingdom. A molecular method for identifying the bacteria has been successfully developed.

The method, designed by the Health Protection Agency (London, UK), was successfully implemented by medical scientists at the Royal Free Hospital (Hampstead, UK). It is a quick and accurate means of identifying which strain of the bacterium is infecting a patient. The multiplex-polymerase chain reaction (PCR), based on identifying unique gene sequences in the bacteria, has the potential to be developed as a rapid screening tool for intensive care units in other parts of the country. It should eventually lead to better patient management with faster and more appropriate treatments for individuals and prompt control of infections to reduce the risk of transmission to other patients

The drug-resistant strains of the bacteria are especially dangerous in intensive care units where, as well as causing pneumonia, they can infect wounds, or cause urinary tract infections. "Some of these new strains of A. baumannii, known as epidemic clones, can spread rapidly and widely between patients and have the potential to cause outbreaks,” said Kerry Williams of the Royal Free Hospital. "We currently encounter two of them at our hospital, so we need a reliable and rapid means of identifying and discriminating between the different clones. We can now get a result from a patient's sample in just four hours. The test also allows us to predict how likely we are to be facing an outbreak.”

"Like MRSA, A. baumannii can be found on the skin without actually causing an infection. The new test is important because it means we can rapidly identify patients who are colonized with drug-resistant strains of the bacteria so that special infection control measures can be put in place. The patient can quickly be isolated if necessary,” added Miss Williams of the Royal Free Hospital. "This reduces the risk of transmission to other patients and the possibility of an outbreak occurring. The ability to distinguish between the clones circulating is also important because it allows us to monitor transmission in our hospital.”

Currently all the Royal Free Hospital strains of bacteria are sent to a reference laboratory for typing by a method called pulsed field gel electrophoresis. The new test, called multiplex-PCR, gives results comparable to the ones produced by the reference laboratory.

The method was described at the Federation of Infection Societies Conference 2007 in Cardiff (Wales,UK), on November 28, 2007.


Related Links:
Health Protection Agency
Royal Free Hospital