Strep Bacteria Resistant to New Antibiotic

Aaron Rowe writes "MSNBC and The Lancet medical journal have reported that the new oxazolidinone antibiotic Zyvox is ineffective against some forms of Staphylococcus aureus."

Comments

Strep != Staph

[ntr0py]

Much like Streptococcus != Staphylococcus.

Is the subject correct?

[IanThePiper]

The subject says Strep, but the summary mentions Staph.

Re:Not a surprise

[AnalogBoy]

Usually, it is triclosan.

Re:Not a surprise

[Dr.Dubious DDQ]

Is it a true antibiotic, or simply some kind of cell-killing agent like bleach?

You know, I'd always thought it was similar to phenols (Remember Dr. Lister's "carbolic acid" [Phenol] antiseptic?), but it appears that triclosan interferes with an enzyme that bacteria use to form their cell walls. I don't know if it's the same thing that Penicillin-related compounds interfere with for the same purpose, though it does imply that bacteria may become resistant to it. It appears that triclosan, like a lot of antibiotics, can activate a "pump" that expels antibiotics from bacteria before they can do damage.

Poking around on Google also brought up an interesting article however, which pointed out that the "resistance" that triclosan induces is ALSO triggered by an awful lot of off the shelf foods from grocery stores...though on the other hand, I don't recall rubbing cinnamon or mustard on my hands like antibacterial soap, either...

Re:Not a surprise

[!splut]

I'm afraid you are confusing the terms "anti-bacterial" and "antibiotic." Anti-bacterial is a very broad, vague term that can be applied to any substance or product that exhibits the ability to kill bacteria. It is a marketing buzzword, used to play on the consumer's fear of microbes and misunderstanding of microbiology. Rubbing alcohol, vinegar, and boiling water would all easily fit under the anti-bacterial label.

The products that you list - anti-bacterial cosmetics and soaps - kill microbes due to very high or low pH, alcohol content, the presence of detergents that lyse cell walls/membranes, and the presence of other toxic chemicals that kill a broad spectrum of organisms in a very general way - the same way bleach kills just about anything you dump it on.

But bleach, alcohol, detergents, etc, are NOT antibiotics. Antibiotics are drug-like compounds that kill bacteria in a targeted fashion, by interfering with growth, cell wall development, and/or metabolic pathways. Antibiotics bind to specific enzymes, proteins, or other structural molecules. Bacteria are able to gain resistance to antibiotics by accumulating changes in the structure of these molecules (via mutations).

So, nonspecific general anti-bacterial compounds, and NOT antibiotics, are present in these cosmetics and soaps. Microbes CANNOT easily develop resistance to nonspecific anti-bacterials. Thus, use of these anti-bacterial products has no effect on the evolution of antibiotic resistant strains of pathogens.

Interestingly, it should be noted that the formulation of many of these household anti-bacterial products is essentially identical to the forerunning "non-anti-bacterial" versions. All liquid hand soaps, for instance, are anti-bacterial to begin with. So the addition of the "anti-bacterial" buzzword on the bottle is just a marketing ploy.

strep & staph

[tid242]

morphologically staph & strep are virtually indistinguishable, they are both gram positive cocci (circular) and are generally differentiated only by their colony morphology (they can also be differentiated by their lysing ability of RBC's, salt tolerability, celluar metabolism etc): strep grows in strings, staph in clusters (as their latin names would imply). but clinically they cause very different infections.

staph is mostly known for surgical infections, staph is the major cause of post-surgical infections and deaths in the US, particularly Staph. areus. oft you may hear of Methicillin-Resistant Staph. Areus (MRSA) in which vanco/zyvox are considered the only therapeutic alternatives (to nafcillin & broad-spectrum B-lactams), although there are always exceptions to the rule Staph is known primarily for wound-infections...

Strep. Streptococcus is the cause of some wound infections such as the infamous necrotizing fascitis ('flesh-eating bacteria'), but it is mostly known for pneumonia (henceforth the name 'strep pneumo'), and 'strep throat' (group B beta-hemolytic strep (if memory serves me correctly)).

there are generally more alternatives for treating strep than there are for staph, clinically. strep is more sensitive to almost all cephalosporins (or at least used to be), macrolides, and a plethora of other abx that staph is not.

(since i saw this on another post, but am too lazy to make another reply, i'll just add) contrary to some peoples' beliefs most of these infections do not resolve very well on their own, which is much the reason infectious disease was the #1 killer 100 years ago, but is near the bottom of the list today. sure strep throat might eventually be 'fought off' but your chances of phyelonephritis or glomereulonephritis (renal infection) are high enough that you'd probably opt for the abx instead of risking it. if you have a Staph. A infection chances are it's from getting knifed, operated on, or otherwise had your skin broken and your tissue innoculated with its resident bacteria. if this is the case you will _not_ get better by yourself, nor are your chances of 'fighting it off' good enough for anyone to expect you to survive. while it is shown that your body requires immune challenge to maintain its ability to ward off disease, you don't seem me opting for an Ebola innoculation to keep my immunity robust.

-tid242

Re:How do they mutate?

[Valdrax]

That's pretty much how it works. However, many species of bacteria can exchange DNA with other species of bacteria. This means that many strains of bacteria get their first resistant variant without having to go through all the trouble of random mutation by swapping with other kinds of bacteria and then surviving while their peers die.

• A nice article on antibotics, drug resistance, and how both work.
• A nice article on gene swapping and how it's confounding evolutionary biology.

Both are slightly technical, but can be skimmed over without missing too much detail.