Kinetic Equations for Longwavelength Excitations of the Quark-Gluon Plasma

We show that longwavelength excitations of the quark-gluon plasma are described by simple kinetic equations which represent the exact equations of motion at leading order in $g$. Properties of the so-called ``hard thermal loops'', i.e. the dominant contributions to amplitudes with soft external lines, find in this approach a natural explanation. In particular, their generating functional appears here as the effective action describing long wavelength excitations of the plasma.Comment: January 8, 1993; 8 pages; SPhT/93-

Use of pharmacodynamic parameters to predict efficacy of combination therapy by using fractional inhibitory concentration kinetics

Combination therapy with antimicrobial agents can be used against bacteria that have reduced susceptibilities to single agents. We studied various tobramycin and ceftazidime dosing regimens against four resistant Pseudomonas aeruginosa strains in an in vitro pharmacokinetic model to determine the usability of combination therapy for the treatment of infections due to resistant bacterial strains. For the selection of an optimal dosing regimen it is necessary to determine which pharmacodynamic parameter best predicts efficacy during combination therapy and to find a simple method for susceptibility testing. An easy-to-use, previously described E-test method was evaluated as a test for susceptibility to combination therapy. That test resulted in a MICcombi, which is the MIC of, for example, tobramycin in the presence of ceftazidime. By dividing the tobramycin and ceftazidime concentration by the MICcombi at each time point during the dosing interval, fractional inhibitory concentration (FIC) curves were constructed, and from these curves new pharmacodynamic parameters for combination therapy were calculated (i.e., AUCcombi, Cmax-combi, T>MIC-combi, and T>FICi, where AUCcombi, Cmax-combi, T>MIC-combi, and T>FICi are the area under the FICcombi curve, the peak concentration of FICcombi, the time that the concentration of the combination is above the MICcombi, and the time above the FIC index, respectively). By stepwise multilinear regression analysis, the pharmacodynamic parameter T>FICi proved to be the best predictor of therapeutic efficacy during combination therapy with tobramycin and ceftazidime (R2 = 0.6821; P < 0.01). We conclude that for combination therapy with tobramycin and ceftazidime the T>FICi is the parameter best predictive of efficacy and that the E-test for susceptibility testing of combination therapy gives promising results. These new pharmacodynamic parameters for combination therapy promise to provide better insight into the rationale behind combination therapy

Electronically assisted surveillance systems of healthcare-associated infections: a systematic review

BackgroundSurveillance of healthcare-associated infections (HAI) is the basis of each infection control programme and, in case of acute care hospitals, should ideally include all hospital wards, medical specialties as well as all types of HAI. Traditional surveillance is labour intensive and electronically assisted surveillance systems (EASS) hold the promise to increase efficiency.ObjectivesTo give insight in the performance characteristics of different approaches to EASS and the quality of the studies designed to evaluate them.MethodsIn this systematic review, online databases were searched and studies that compared an EASS with a traditional surveillance method were included. Two different indicators were extracted from each study, one regarding the quality of design (including reporting efficiency) and one based on the performance (e.g. specificity and sensitivity) of the EASS presented.ResultsA total of 78 studies were included. The majority of EASS (n = 72) consisted of an algorithm-based selection step followed by confirmatory assessment. The algorithms used different sets of variables. Only a minority (n = 7) of EASS were hospital-wide and designed to detect all types of HAI. Sensitivity of EASS was generally high (> 0.8), but specificity varied (0.37-1). Less than 20% (n = 14) of the studies presented data on the efficiency gains achieved.ConclusionsElectronically assisted surveillance of HAI has yet to reach a mature stage and to be used routinely in healthcare settings. We recommend that future studies on the development and implementation of EASS of HAI focus on thorough validation, reproducibility, standardised datasets and detailed information on efficiency

Serotyping, ribotyping, PCR-mediated ribosomal 16S-23S spacer analysis and arbitrarily primed PCR for epidemiological studies on Legionella pneumophila

Fifty clinical and environmental isolates of Legionella pneumophila were typed serologically and by DNA fingerprinting using arbitrarily primed polymerase chain reaction (AP-PCR). Furthermore, variability in and around ribosomal operons was assessed by conventional ribotyping and PCR-mediated amplification of the spacer region separating the 16S and 23S genes. It appears that serotyping suffers from low resolution capabilities, and ribotyping and spacer PCR display intermediate resolving capabilities, whereas AP-PCR is more discriminating. Results from AP-PCR and both forms of ribotyping analysis correlate with epidemiological and environmental data. It is suggested that AP-PCR typing may be the method of choice for rapidly determining clonality among L. pneumophila isolates