How does multiple resistance develops in bacteria?

As the previous people have stated, patients not finishing their antibiotic therapy (i.e., not taking antibiotics for the full 10 days as prescribed, typically stopping after two or three days once the patient feels better), doctors blindly prescribing antibiotics to placate patients who demand them for symptoms not caused by bacterial infections in the first place (such as a cold or flu, both caused by VIRUSES, against which antibiotics have ZERO effect), AND the overuse of a specific type of antibiotic to treat a specific condition, all contribute to multiply-resistant bacteria.





Here's how it happens from a microbiological standpoint. As a real-life example, I'll use Streptococcus pneumoniae, the causative agent of strep throat, ear infections, and some types of bacterial pneumonia, amongst others. About 10 years after Fleming discovered penicillin early in the 20th century, it was widely used to treat S. pneumoniae-related infections. It was very efficient; however, after another 10 years or so, doctors and researchers were noticing that patients weren't recovering as well with the same penicillin dose, so they increased the dose. Worked fine for another few years, then same phenomenon again. This is the mechanism: 1. Picture 10 million S. pneumoniae bacteria in a typical ear infection (not an unreasonable bacterial count in an average infection). 2. Doctor puts you on penicillin for 10 days, but one or both of the following occurs: (a) the dose the doctor gave you killed 99.9% of the bacteria, but 0.1%, or 10,000 bacteria, have survived, resistant to penicillin and free to reproduce, even if more penicillin is given, as the weaker bacteria have been "weeded out", so to speak, or (b) after maybe 3 days or so, your earache is gone and you decide to stop taking the antibiotics because your ear doesn't hurt anymore; the bacteria had stopped multiplying when you were taking the penicillin, but now they're free to reproduce, and again, the weaker ones were "weeded out" by the initial 3 days' worth of penicillin.





Fast-forward a few decades; in 1970, it is well known that most S. pneumoniae strains don't respond to treatment with penicillin, so they try another type of antibiotic: tetracycline. Works well for a few years, then the same thing happens: S. pneumoniae becomes resistant to tetracycline in addition to penicillin. Try a few other types of antibiotics on it, throw in the above treatment scenario(s), add another few decades, and we now have, apart from multiply-resistant S. pneumoniae, MRSA (methicillin-resistant Staphylococcus aureus) avd VRE (vancomycin-resistant E. coli), both of which, in extreme cases, can and have caused fatalities in patients where they've acquired the resistant bacteria while hospitalized for totally unrelated issues, like a hernia or other condition requiring some surgery.





A scary thought.

How does multiple resistance develops in bacteria?
Here you go:





http://www.fda.gov/fdac/features/795_ant...
Reply:It's a direct result of patients not completing antibiotic therapy and from over prescribing and overuse of antibiotics. Patients demand antiibotics for every little thing. Doctors were too quick to prescribe. Patients stopped taking the meds as soon as they felt better instead of completing the regimen. We in health care have already been cautioned about antibiotic overuse.

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