In bacteremia, rapid isolation of infectious agents and determination of their ant ibiotic susceptibility are very important for appropriate treatment decision. Although antibiotic susceptibility tests results are determined in 48 hours by the standard method, direct susceptibility tests which are obtained from directly positive blood culture bottles can provide results in 24 hours. However, since direct susceptibility t esting has not been standardized, there is need for further investigation with different microorganisms and antibiotic s. In this study, the result of direct disk diffusion tests were compared with those of standard disk diffusion method in 200 positive blo od cultures. A total of 21 different antibiotics were evaluated and the results of bo th methods had 93.6% agreement.
There were 4.8% minor, 0.9% major and 0.5% very major discrepancies between th e direct diffusion test and the standard method, and major and very major discrepancies were found to be associated mostly with oxacillin, vancomycin, clindamycin, ciprofloxacin and gentamicin. In addition, although the su sceptibility categories were in agreement, there was a difference of 58% between the zonal diam eters determined by both methods.
In bacteremia, direct disk diffusion method for antimicrobial susceptibility testi ng can be performed in order to start the effective treatment as soon as posible. However, even though very major discrepancies are observ ed infrequently, standard susceptibility tests should also be performed to confirm the test results.
Key words: Blood Culture, Standard Susceptibility Test, Direct Susceptibility Test
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