Steno superbug genome sequenced

Source: http://www.bristol.ac.uk/news/2008/212017945300.html

The genome of a newly-emerging superbug, commonly known as Steno, has been sequenced by scientists at the Wellcome Trust Sanger Institute and the University of Bristol.

The results of the Stenotrophomonas maltophilia sequencing, published in Genome Biology, reveal an organism with a remarkable capacity for drug resistance.

"This is the latest in an ever-increasing list of antibiotic-resistant hospital superbugs," senior author Dr Matthew Avison, from the University of Bristol, said. "The degree of resistance it shows is very worrying. Strains are now emerging that are resistant to all available antibiotics, and no new drugs capable of combating these 'pan-resistant' strains are currently in development."

Pan-resistant Steno infections are at least as hard to treat as MRSA and C.diff infections. But although it is common in the environment, Steno infections are rarer than MRSA and C.diff infections and are exclusively hospital-acquired.

Steno flourishes in moist environments, such as around taps and shower heads, and can be transferred to patients. It is distinct in the way it causes infection and can only get into the body via devices such as catheters or ventilation tubes that are left in place for long periods of time. Long-dwelling catheters are used most often for seriously ill patients and some undergoing chemotherapy.

Steno can stick to the catheter and grow into a 'biofilm'. When the catheter is next flushed, the Steno biofilm can enter the patient's bloodstream. If their immune system is impaired (which is often the case in the seriously ill and those undergoing chemotherapy) the organism can multiply and cause septicaemia. The gravity of this situation has been underlined by the new research, since these patients will be treated with antibiotics against which Steno is largely resistant.

There are approximately 1,000 reports of Steno blood poisoning in the UK each year, with a mortality rate of about 30 per cent. The organism is also found in the lungs of many adults with cystic fibrosis, and causes ventilator-associated pneumonias, particularly in elderly intensive-care patients.

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