Investigation of the In Vitro Effectiveness of Aztreonam/Avibactam, Colistin/Apramycin, and Meropenem/Apramycin Combinations Against Carbapenemase-Producing, Extensively Drug-Resistant Klebsiella pneumoniae Strains.

This study aimed at investigating the in vitro effectiveness of aztreonam/avibactam, colistin/avibactam, colistin/apramycin, and meropenem/apramycin combinations against carbapenemase-producing, extensively drug-resistant (XDR) Klebsiella pneumoniae strains. This study evaluated 38 carbapenem-resistant, carbapenemase-producing, and XDR K. pneumoniae strains. The checkerboard method was used to examine the efficacy of aztreonam/avibactam, and meropenem/apramycin combinations in all strains and the colistin/apramycin combination in colistin-resistant strains (n = 26). It was found that when used alone, aztreonam and avibactam had high minimum inhibitory concentration values in all strains and that all strains were resistant to aztreonam. Nevertheless, the aztreonam/avibactam combination was found to have a synergistic effect against all strains. Apramycin alone was effective against 30 K. pneumoniae strains (79%); however, 8 strains (21%) were found to be resistant. In the synergy testing of 26 colistin-resistant strains with the checkerboard method, the colistin/apramycin combination was found to have a synergistic effect against 4 strains (15.3%), an antagonistic effect against 8 strains (30.7%), and an additive effect against 14 strains (54%). By comparison, the meropenem/apramycin combination had a synergistic effect against 20 strains (52%) and an additive effect against 12 strains (31%). The aztreonam/avibactam combination showed a high in vitro synergistic effect on carbapenemase-producing and XDR K. pneumoniae strains, such as Metallo-ß-lactamase, and provided good prospects for the successful treatment. The meropenem/apramycin combination was also highly synergistic. The synergistic effects were low for the colistin/apramycin combination that was tested on colistin-resistant strains. However, it is promising that apramycin has low minimal inhibitory concentration values.

Comparison of the Xpert CARBA-R Test and Phenotypical Tests for Detection of Carbapenemases Types in Multidrug Resistant K. pneumoniae Isolates.

BACKGROUND: The objective of this study is to evaluate the performance of the Xpert CARBA-R Test and the phenotyping confirmation tests (MHT, CIM, Mastdiscs, and Carba NP) for the detection of carbapenemases in multidrug resistant (MDR) Klebsiella pneumoniae isolates. METHODS: A total of 68 MDR K. pneumoniae isolates isolated from various clinical samples, were included in the study. The identification and antibiotic susceptibility tests of these isolates were performed using the VITEK®2 (BioMérieux, France) automated system. The Xpert CARBA-R test was used as the molecular method. The combined disc method was performed using Mastdiscs Combi-D70C that includes four antibiotic discs with specific in-hibitors. The modified Hodge test was performed on all isolates. Carbapenemase inactivation method (CIM) and Carba NP test was used for carbapenemase enzyme production. RESULTS: Of the 50 isolates detected to produce carbapenemase by the molecular method (Xpert CARBA-R Test), 45 (90%) were detected by MHT, 39 (78%) were detected by CIM, and 42 (84%) were detected by Mastdiscs, while all the 50 isolates were detected by the Carba NP test. When the Xpert CARBA-R Test was taken as a reference, significant differences were found between the Carba NP and Xpert CARBA-R Test. There was no significant difference between the other phenotypic methods and Xpert CARBA-R Test. The sensitivity of the MHT, CIM, combined disc, and Carba NP tests was calculated as 0.90, 0.78, 0.84, and 1 and their specificity was calculated as 0.83, 0.83, 0.83 and 0, respectively. According to the gold standard, the predictive power of MHT, CIM, and MAST methods was found to be statistically significant. CONCLUSIONS: There are various methods of carbapenemase detection, including phenotypic and molecular methods. There is no single detection method that is valid and usable in all conditions. Laboratories should choose a suitable carbapenemase detection and confirmation method in line with their needs, economic conditions, and infrastructures. Although the detection of the presence of carbapenemase by molecular methods is fast and reliable, low-cost phenotypic tests can be used in laboratories that do not have this possibility. It is an important advantage that the combined disc method can also determine the enzyme type.

Results of a paired catchment analysis of forest thinning in Turkey in relation to forest management options.

Adaptation to climate change has become a more serious concern as IPCC assessment reports estimate a rise of up to 2°C in average global temperatures by the end of the century. Several recently published studies have underlined the importance of forest management in mitigating the impacts of climate change and in supporting the adaptation capacity of the ecosystem. This study focuses on the role of water-related forest services in this adaptation process. The effects of forestry practices on streamflow can best be determined by paired watershed analysis. The impact of two cutting treatments on runoff was analyzed by a paired experimental watershed study in the Belgrade Forest and the results were evaluated in relation to similar experiments conducted around the world. Forest thinning treatments at 11% and 18% were carried out in a mature oak-beech forest ecosystem over different time periods. Although the thinning increased the runoff statistically, the amount of surplus water remained <5% of the annual water yield. Evidently, the hydrologic response of the watersheds was low due to the reduced intensity of the timber harvest. Finally, the results were combined with those of global studies on thinning, clearcutting and species conversion with the aim of formulating management options for adaptation.

Comparison of Novel Blood Culture System DL-Bt112TM with BacT/Alert 3DTM by Using Clinical Samples.

BACKGROUND: Blood cultures are the main diagnostic laboratory tool to detect bloodstream infections. Many clinical microbiology laboratories utilize automated blood culture systems to isolate infectious agents from blood samples. The diagnostic performance and time-to-detection values of the novel automated blood culture system, DLBt112TM (DL), was compared with BacT/Alert 3DTM (B3D) in this prospective comparative study with clinical samples. METHODS: A total of 356 blood culture sets (178 sets for each system) were evaluated over a 6-month period in a university hospital. Two sets of blood culture samples (one for DL and one for B3D) were drawn from intensive care unit patients who were suspected to have bloodstream infections. BacT/ALERT FA FAN® Aerobic/Anaerobic blood culture bottles for B3D and FAN adult anaerobic/aerobic blood culture bottles for DL were used. The Vitek® 2 automated system was used for identification of the isolated bacteria. RESULTS: We evaluated 178 sets from 105 patients consisting of 712 blood culture bottles in total. In total, 294 negative bottles and 47 positive bottles were detected by both systems. Recovery rate of the B3D (96.7%) was significantly higher than that of DL (79.0) (p < 0.05). We determined significant differences between DL and B3D in terms of time-to-detection values for gram negatives (p = 0.006) and contaminants (p = 0.048). Overall, B3D had shorter time-to-detection mean values. CONCLUSIONS: The recovery rate of DL was unfavorably low and time-to-detection values for DL were significantly higher than that of B3D. This might result from the ingredients of the culture bottles since the detection technologies of the systems were similar.