Comparison of time-to-detection of Mindray TDR and BacT/ALERT®3D blood culture systems using simulated blood cultures.

PURPOSE: Blood culture (BC) is the standard for diagnosing bloodstream infections. Available blood culture (BC) systems have been developed to shorten the time to detection (TTD) of positive BCs. This study aimed to evaluate the performance of the Mindray TDR automatic BC system by comparing it with the BacT/ALERT®3D system. METHODS: Sixteen reference strains and 14 clinical isolates were used. Serial dilutions were prepared from all bacterial and yeast colonies with a final concentration of 100 CFU/ml and 10 CFU/ml. The prepared solutions were simultaneously inoculated into the bottles of both systems and placed in blood culture devices. RESULTS: Three hundred and fifty-two (176 BacT/ALERT®3D and 176 Mindray TDR-X060) blood culture bottles were evaluated, 336 aerobic and 16 anaerobic. At both 10 CFU/ml and 100 CFU/ml dilution, there was no significant difference between the two systems in terms of mean detection times for all isolates (p = 0.965, p = 0.245). When evaluated according to the type of organism, the detection time of gram-positive bacteria at 10 CFU/ml dilution was significantly shorter in the BacT/ALERT system (p = 0.019), whereas detection time for yeasts was significantly shorter with the Mindray system (p = 0.047). The number of anaerobic bacteria was too small to draw statistical conclusions, but we observed a trend of shorter detection times in the Mindray TDR-X060 system. CONCLUSION: Two systems with similar operating principles showed different concentrations-dependent performances in terms of positivity detection times depending on the type of microorganism. Mindray TDR-X060 system has been found to be safe to use at high concentrations with this at lower concentrations further comparative studies are needed on the newly introduced Mindray system.

Investigation of in vitro efficacy of quercetin-meropenem combination in carbapenemase-producing Klebsiella pneumoniae isolates.

INTRODUCTION: In recent years, the rapid spread of carbapenem-resistant K. pneumoniae, their higher mortality rates, and limited treatment alternatives cause difficulties in the treatment of these infections. New treatment alternatives are needed to cope with resistant strains. In recent years, natural products such as Quercetin have started to be preferred in combination studies due to their antimicrobial effects and low side-effect profiles. The aim of this study was to investigate the in vitro efficacy of the combination of Quercetin and Meropenem on carbapenemase-producing (blaKPC, blaNDM, blaVIM, blaOXA-48, and blaIMP), carbapenem-resistant K.pneumoniae isolates using the checkerboard method. METHODOLOGY: Thirty Carbapenem-resistant K.pneumoniae strains in the culture collection of our laboratory were included in our study. Carbapenemase genes were determined using the Xpert® Carba-R (Cepheid, USA). Synergism with meropenem was assessed by checkerboard analysis, followed by FIC index, and combination index calculation. RESULTS: Twenty (66.6%) strains had OXA-48, 6 (20%) NDM, 1 (3.3%) KPC, 1 (3.3%) OXA-48+NDM genes, and 2 strains (6.6%) gene could not be detected. In the Quercetin and Meropenem combination study, synergy was found in 24 (80%) of the strains; an additive effect was found in 5 (16.6%) and an antagonist effect in 1 (3.3%). In 19 (63.3%) of the strains, meropenem MIC values were below the sensitive limit (MIC ≤ 2 µg/mL). CONCLUSIONS: Although the combination of quercetin and meropenem has a high synergistic effect in carbapenem-resistant K. pneumoniae isolates, it seems that the carbapenemase species affects this situation. however, more work is needed on this subject.

Investigation of In-vitro Efficacy of Intravenous Fosfomycin in Extensively Drug-Resistant Klebsiella pneumoniae Isolates and Effect of Glucose 6-Phosphate on Sensitivity Results.

BACKGROUND: The aim of this study was to determine the in vitro efficacy of intravenous (IV) fosfomycin against extensively drug-resistant Enterobacterales strains and the effect of glucose 6-phosphate (G6-P) on sensitivity results. MATERIAL METHOD: Thirty-two extensively drug-resistant Klebsiella pneumonia strains were included in the study. Detection of the carbapenemase genes was performed using the Gene-Xpert® System Carba R® kit. Susceptibility of IV fosfomycin was assessed using the agar dilution method. The agar dilution method was repeated using Muller-Hinton Agar medium without G6-P to assess the effect of G6-P on sensitivity results. RESULTS: All strains in the study produced carbapenemases and were resistant to all drugs tested, including carbapenems, piperacillin-tazobactam, ceftriaxone, and ceftazidime. Fosfomycin resistance was detected in 3 (9.3%) strains. When the sensitivity test was repeated without G6-P, fosfomycin resistance was detected in 82.7% of the fosfomycin-susceptible strains. The Gene-Xpert® System showed NDM-1 in 46.8%, OXA-48 in 18.7%, KPC in 3.1%, and NDM-1 + OXA-48 in 21.8% of the strains. OXA-48 was detected in one of the resistant strains, and none of the viable genes were detected in two of the resistant strains. CONCLUSION: This study shows that IV fosfomycin is a potentially important treatment alternative for infections caused by common resistant strains. Accurate results may not be obtained unless G6-P is used in the agar dilution method for in vitro susceptibility studies of fosfomycin.