The threat from the pink corner.

In terms of numbers of isolates, the greatest present resistance problems arise with gram-positive pathogens (which stain purple/black in Gram's method), especially methicillin-resistant Staphylococcus aureus (MRSA). But, is the MRSA problem--by its size--blinding us to something ultimately more dangerous: the slow emergence of gram-negative pathogens (which stain pink) with resistance to all reliable antibiotics? Although presently rare, 'pan-resistant' gram-negative bacteria--predominantly strains of Pseudomonas aeruginosa and Acinetobacter baumannii--have more comprehensive resistance than any gram-positive pathogen. They already pose treatment problems in compromised hospital patients, especially in specialist units, as well in particular groups, such as cystic fibrosis patents. Disturbingly, there is a near-total lack of developmental antibiotics active against gram-negative pathogens.