New fluoroquinolones expected on the market soon will aggravate this problem, he adds. Meanwhile, overuse of fluoroquinolones depletes their effectiveness. Dr. Hooton suggests that instead of fluoroquinolones, older antibiotics such as amoxicillin could be used to treat most community-acquired Streptococcus pneumoniae infections. Tough breaks Misplaced concerns and marketing pressure are just two of the myriad factors that contribute to the threat of widespread antibiotic resistance. Among other things, the laboratory testing methods for measuring resistance are far from foolproof.
Results can differ depending on the lab or the test.
In addition, the break points used to distinguish an organism's susceptibility to an antimicrobial are not always set at the correct level. As a result, in vitro tests do not always accurately predict in vivo effectiveness, especially for respiratory pathogens. Break points are vital because labs use them to determine which isolates are susceptible to various antibiotics. If the break point for one antibiotic is too high, labs are more likely to report that a microbe is resistant to that antibiotic, which will motivate physicians to prescribe a stronger agent. The National Committee for Clinical Laboratory Standards sets the break points.