[Evaluation of a fully automated microbiology system, RAISUS to determine antimicrobial susceptibility for the isolates of Haemophilus influenzae].
A fully automated microbiology system, RAISUS (Nissui Pharmaceuticals Co., Ltd., Tokyo) was evaluated to determine antimicrobial susceptibility of the isolates of Haemophilus influenzae. The test procedures were fully automated from the inoculation of the test organism through the reading of growth-endpoint on the test plates. Also, Haemophilus Test Medium (HTM) broth supplemented with oxidation-reduction color dye, Redox, assures us of enough bacterial growth and of accurate interpretation of bacterial growth. In the evaluation, the RAISUS provided 99.2% (1,012 of 1,020 testings) agreement in MIC determinations, and 96.4% (983 of 1,020 testings) agreement in category interpretations when compared to the results obtained by the NCCLS M7-A6 and M100-S14 standards. Also, ampicillin (ABPC)-resistance in H. influenzae was characterized by the RAISUS through the addition of clavulanic acid (CVA) into the test broth. Sixteen beta-lactamase-positive isolates resulted in conversion to susceptible interpretation by addition of CVA, whereas the remaining 11 isolates did not. These unaffected isolates were presumptively identified as being beta-lactamase positive, ABPC/CVA-resistant (BLPACR). Of fifty-four beta-lactamase-negative isolates, twelve were regarded as being beta-lactamase negative, ampicillin-resistant (BLNAR) due to 4 microg/ml or greater MICs against ABPC and unaffected MICs by CVA. With the results obtained, it is concluded that the RAISUS can provide comparable determinations for the isolates of H. influenzae, in both MIC determinations and category interpretations, to the NCCLS standards, and is applicable to the routine testing in clinical laboratories.
Nakasone
Isamu
I
Clinical Laboratories, University Hospital of the Ryukyus, Nakagami-Okinawa 903-0215. isamu@jim.u-ryukyu.ac.jp
Yamane
Nobuhisa
N
Onaga
Sayuri
S
D001431:Bacteriological Techniques / Q000295:instrumentation*; D024881:Drug Resistance, Bacterial; D006193:Haemophilus influenzae / Q000187:drug effects*