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Acinetobacter baumannii, the hospital opportunist

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12.01.2004

Acinetobacter baumannii is an opportunistic pathogen operating in hospitals creating serious infections such as pneumonia. It principally affects patients who have weakened health and this is why we call it opportunistic. Moreover, the mortality rate from these infections are usually high given, on the one hand, the weakness of the patient and, on the other, A. baumannii is resistant to many antibiotics. Furthermore, once a specific course of treatment is prescribed for A. Baumannii, the pathogen has a great capacity for acquiring resistance to these antibiotics.

To tackle this problem it is essential to observe, in an ongoing manner, the new resistances the bacteria develops, in order to know what kind of antibiotic has to be used to treat patients. In order to carry out these analyses, the gene for the new acquired resistance has to be identified and isolated and also the presence or otherwise of integrons has to be determined.

Integrons

Integrons are chains of genes wherein many of the resistances acquired by the A. baumannii bacteria are found. The pathogen also has other options for their acquisition but it is the integrons that provide the most efficacious way to acquire and transmit the resistances, given that, apart from acquiring resistances, integrons have great mobility and can transfer from one location of the A. baumannii chromosome to another.

This mobility allows them to pass from one strain of the bacteria to another. This means that all the resistances acquired by a strain of A. baumannii can be transmitted to another and the species can thus modify and regenerate itself continuously. Moreover, as it has a promotoros, the bacteria is always activating or expressing all the resistances held in the integron.

Attempting to improve control

Analysing and isolating a number of A. baumannii strains from hospitals, it has been shown that most have integrons. Thus, it is highly probable that A. baumannii becomes resistant to the best antibiotics that exist today and that this resistance is transmitted via integrons. Moreover, A. baumannii strains have been identified that are resistant to the most common antibiotics used today.

If this is confirmed, the mortality rate due to infections created by the bacteria may even be greater than thought to date, given that there is no antibiotic capable of tackling the infection. It should be taken into account that the number of hospital patients affected by infections caused by A. baumannii is not great, but the gravity of the problem lies in the rate of mortality of these cases.

There currently exist methods to genetically distinguish A. baumannii strains from each other, but the aim at the moment is to obtain a method of indicating the presence of integrons and their resistance in these strains. Of course, this method of detection has to be standardised and, at the same time, practical, for its clinical use.

That is to say, the option of the researchers has been to try to improve control with respect to A. baumannii given that there is currently no substitutes for the antibiotics used to date. In order to achieve this improved control, it is essential to detect the infection in time and know if A. baumannii has produced it. The resistances of the strains must also be known and if they have integrons. Once this detailed information is gathered, new systems for the control of infections can be introduced in order keep down the rate of mortality due to A. baumannii.


Contact :
Garazi Andonegi
ELHUYAR Fundazioa
garazi@elhuyar.com
(+34) 943363040

Garazi Andonegi | Source: Basque research
Further information: www.basqueresearch.com/berria_irakurri.asp?Gelaxka=1_1&Berri_Kod=383&hizk=I
www.ehu.es

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