Well, "news" perhaps isn’t the best description since we’ve been seeing it for a while, but a paper in an upcoming edition of the Journal of Clinical Microbiology (Gold et al. 2014) entitled "Amikacin resistance in Staphylococcus pseudintermedius isolated from dogs" provides published support for the trend we’ve been seeing.
Staphylococcus pseudintermedius is an important cause of infections in dogs, and a resistant form, MRSP (methicillin-resistant Staph pseud) is a major problem. MRSP also does a great job of becoming resistant to additional antibiotics, usually by picking up resistance genes from other bacteria. We’ve rapidly lost most of our typical antibiotic treatment options for many MRSP strains, and are left with only a couple of viable drugs. One of those is amikacin, an antibiotic we try not to use when we don’t have to because it has to be injected, and because it can be hard on the kidneys. However, it’s literally a lifesaver in some cases.
Over the past year or two (unsurprisingly, really), we’ve been seeing some amikacin resistance in MRSP strains. I say that’s unsurprising because, with bacteria in general (and MRSP in particular), we’re trapped in a game of "use it and lose it." Any time we use an antibiotic, there is some potential for resistance to develop.
The study by Gold et al looked at 422 Staph pseud from dogs, and found that MRSP were significantly more likely to be amikacin resistant, with a rather astounding 37% amikacin resistance rate in their MRSP collection. Amikacin-resistant strains were also more likely to be resistant to a range of other antibiotics, regardless of their methicillin-resistance.
What do we do?
Tough question. Bacteria eventually seem to outsmart us most of the time (or we seem to "out-dumb" them, since it’s often our poor use of antibiotics that leads to problems).
So, what can be done?
Prevention is better than cure: MRSP infections are almost invariably secondary problems. Preventing or limiting underlying disease (e.g. controlling allergic skin disease) can greatly reduce the number of infections and the amount of antibiotics used to treat them.
Infection control: MRSP surgical site infections are increasingly common, and using good infection control practices should help limit them.
Use them right: Making sure drugs are given as prescribed with proper dosing (amount and frequency), and limiting the use of the few remaining MRSP treatment options for cases that really need them are important.
Antibiotic alternatives: Antibiotics aren’t always needed to treat infections. Topical therapy with things like chlorhexidine shampoo can be highly effective for skin infections, and can save antibiotics for infections that can’t be treated otherwise.
Will these steps stop the scourge of antibiotic resistance?
No. But they might buy us some more time to figure out how to better handle this and to save some of our limited remaining antibiotic options.