Rapid, reliable determination of microorganisms from blood is one of the most important functions of clinical microbiology laboratory. In this study, the importance of Gram stain and methylene blue stain were investigated for all of the blood culture bottles monitored by the BacT/Alert system. A total of 750 blood cultures were examinied. Of these 142 were positive signaling bottles and 608 had no signal. Microorganisms were observed in 115 out of 142 positive blood culture bottles. Of these 110 were aerobic and five were anaerobic microorganisms. No microorganisms were detected in 27 blood culture bottles despite positive signaling, Brucella spp. were isolated from two blood cultures on the eighth day of incubation (The false positive rate was 18 %). No microorganisms were detected in 606 out of 608 negative signaling bottles. Gram negative microorganisms were observed in two bottles and P.aeruginosa were isolated from both of these cultures (The false negative rate was 0.3 %).

Although the evaluation of Gram stained smears were more difficult for BacT/Alert FAN media due to the charcoal particles in the media, there were no problems associated with mehylene blue stain . Therefore, both staining methods can be used simultaneously for microscopic examination.