Susceptibility of Branhamella catarrhalis to sulphamethoxazole and trimethoprim

Fifty strains of Branhamella catarrhalis were examined for susceptibility to sulphamethoxazole, trimethoprim and a combination of the two by determinating minimum inhibitory concentrations (MICs) and fractional inhibitory concentrations (FICs). All strains were susceptible to sulphamethoxazole and resistant to trimethoprim. On the basis of the MIC results it was predicted that greater synergy between sulphamethoxazole and trimethoprim would be observed with approximately equal proportions of each component. The lowest FIC values were obtained with a ratio of 1:1 and the greatest synergy was observed at this ratio with 39 strains (78%). Only seven strains were most synergistically inhibited at the ratio of 20:1 (sulphamethoxazole: trimethoprim) although this ratio was still synergic for most strains. Overall the 1:20 ratio was not synergic

Design of a Mobile Agent-Based Adaptive Communication Middleware for Federations of Critical Infrastructure Simulations

Abstract. The simulation of critical infrastructures (CI) can involve the use of diverse domain specific simulators that run on geographi-cally distant sites. These diverse simulators must then be coordinated to run concurrently in order to evaluate the performance of critical infrastructures which influence each other, especially in emergency or resource-critical situations. We therefore describe the design of an adap-tive communication middleware that provides reliable and real-time one-to-one and group communications for federations of CI simulators over a wide-area network (WAN). The proposed middleware is composed of mobile agent-based peer-to-peer (P2P) overlays, called virtual networks (VNets), to enable resilient, adaptive and real-time communications over unreliable and dynamic physical networks (PNets). The autonomous software agents comprising the communication middleware monitor their performance and the underlying PNet, and dynamically adapt the P2P overlay and migrate over the PNet in order to optimize communications according to the requirements of the federation and the current condi-tions of the PNet. Reliable communications is provided via redundancy within the communication middleware and intelligent migration of agents over the PNet. The proposed middleware integrates security methods in order to protect the communication infrastructure against attacks and provide privacy and anonymity to the participants of the federation. Ex-periments with an initial version of the communication middleware over a real-life networking testbed show that promising improvements can be obtained for unicast and group communications via the agent migration capability of our middleware

Surveillance for antimicrobial resistance in Australian isolates of Clostridium difficile, 2013–14

Objectives: The objective of this study was to determine the activity of fidaxomicin and comparator antimicrobials against Clostridium difficile isolated from patients with C. difficile infection (CDI) in Australian hospitals and in the community. Methods: One private and one public laboratory from five states in Australia submitted a total of 474 isolates/PCR-positive stool samples during three collection periods in August-September 2013 (n=175), February-March 2014 (n=134) and August-September 2014 (n=165). Isolate identification was confirmed by selective culture for C. difficile and a proportion of isolates from each state were characterized by PCR for toxin genes and PCR ribotyping. MICs of fidaxomicin and eight comparator antimicrobials were determined for all isolates using agar methodology. Results: Site collection yielded 440 isolates of C. difficile and PCR revealed a heterogeneous strain population comprising 37 different PCR ribotypes (RTs), 95% of whichwere positive for tcdA and tcdB (A+B+). The most common RTs were 014 (29.8%) and 002 (15.9%). Epidemic RT 027 was not identified; however, small numbers of virulent RTs 078 and 244 were found. Resistance to vancomycin, metronidazole and fidaxomicin was not detected and resistance to moxifloxacin was very low (3.4%). Fidaxomicin showed potent in vitro activity against all 440 isolates (MIC50/MIC90 0.03/0.12 mg/L) and was superior to metronidazole (MIC50/MIC90 0.25/0.5 mg/L) and vancomycin (MIC50/MIC90 1/2 mg/L). Conclusions: These data confirm the potent in vitro activity of fidaxomicin against C. difficile. Moreover, this study provides an important baseline for ongoing long-term surveillance of antimicrobial resistance and prospective tracking of prominent and emerging strain types