快猫短视频

IN ANOTHER attempt to combat the superbug Staphylococcus aureus,
researchers in Japan have nailed the bacterium鈥檚 genetic blueprint. It appears
that the bacterium has a ferocious arsenal of tricks鈥攁nd may be even more
dangerous than doctors realise.

Staph evolves resistance to antibiotics fearsomely fast. While most bacteria
take years to become resistant to an antibiotic such as methicillin, staph
outwitted the drug all too quickly. 鈥淢ethicillin resistance appeared one year
after its launch,鈥� says Keiichi Hiramatsu of Juntendo University in Tokyo.

To uncover staph鈥檚 tricks, Hiramatsu鈥檚 team sequenced the genomes of two
strains: one that resists methicillin and one that resists vancomycin, a crucial
antibiotic often used as a last resort. It turned out that the two strains鈥�
genomes varied by as much as 4 per cent.

Hiramatsu says this highlights the bug鈥檚 incredible efficiency at stealing
genes. Staph probably picked up its resistance to most antibiotics from genes it
acquired from other bacteria, although Hiramatsu thinks vancomycin resistance
arose due to a mutation. A detailed look at individual bases in the genomes
could confirm this, he says. Staph has also acquired genes from all sorts of
other bacteria and even from more complex creatures鈥攊ncluding people.

The Japanese team also found that genes for 鈥渟uperantigens鈥濃�攖oxins that
can spark an out-of-control immune reaction in people鈥攁re
duplicated and repeated at several sites in the genome. 鈥淭his signifies that
each strain of S. aureus that resides in our noses is capable of
generating numerous new toxins and assaulting human bodies,鈥� says Hiramatsu.

The upshot is that staph might be even more dangerous than anyone
thought. For example, it could be involved in Kawasaki disease, a potentially
fatal inflammatory illness in children that researchers believe is caused by
superantigens, Hiramatsu says. Searching for new toxins from S. aureus
could confirm this, he says.