Hospitals face a new superbug threat with the rise of a potentially lethal microbe that is at least as hard to treat as MRSA, scientists warned today. There were 1,000 cases of blood poisoning caused by Stenotrophomonas maltophilia, or Steno, in the UK last year, of which around 300 were fatal, said researchers from the Wellcome Trust and Bristol University. Some strains of Steno, which is difficult to remove by normal cleaning, are resistant to all available antibiotics. This makes them as dangerous as the current two deadliest superbugs, MRSA and Clostridium difficile.