To compare the tigecycline activity profile against Acinetobacter spp. by Etest versus broth microdilution in isolates with high Etest MIC. Acinetobacter spp. isolates with tigecycline MICs of ≥0.5 mg/L determined by commercially developed Etests strips (January 2006 to July 2007) in five Spanish hospitals were considered. Values were rounded to the nearest upper double-dilution. Susceptibility by broth microdilution following CLSI (formerly NCCLS) recommendations, as the reference method, was determined in a central laboratory. BSAC breakpoints were used: susceptible ≤1 mg/L; intermediate = 2 mg/L; and resistant >2 mg/L. One hundred and forty-eight isolates were collected: 12 isolates with a tigecycline Etest MIC of 0.5 mg/L, 14 with 1 mg/L, 86 with 2 mg/L, 31 with 4 mg/L and 5 with 8 mg/L. Isolates with Etest MICs of 0.5–1 mg/L showed the same values by broth microdilution. Among isolates with Etest MICs of 2 mg/L, only 5.8% of strains showed the same value by both methods (88.4% showed values that were one or two dilutions lower by microdilution). None of the 36 isolates with Etest MICs of 4–8 mg/L showed the same value by both methods, with values at least two dilutions lower by microdilution. Weak correlation (R = 0.238; P ≤ 0.001) was found between both methods. All 26 Etest susceptible isolates, 80/86 (93.0%) Etest intermediate and 32/36 (88.9%) Etest resistant strains were susceptible by microdilution. Caution should be taken in interpreting Etest MICs of ≥2 mg/L for Acinetobacter spp. since strains with Etest MICs of 2–4 mg/L are susceptible when tested by microdilution. False non-susceptibility by Etest may exclude tigecycline as a therapeutic option in a field where multiresistance is the rule.
Public goods games (PGGs) describe situations in which individuals contribute to a good at a private cost, but others can free-ride by receiving a share of the public benefit at no cost. The game occurs within local neighbourhoods, which are subsets of the whole population. Free-riding and maximal production are two extremes of a continuous spectrum of traits. We study the adaptive dynamics of production and neighbourhood size. We allow the public good production and the neighbourhood size to coevolve and observe evolutionary branching. We explain how an initially monomorphic population undergoes evolutionary branching in two dimensions to become a dimorphic population characterized by extremes of the spectrum of trait values. We find that population size plays a crucial role in determining the final state of the population. Small populations may not branch or may be subject to extinction of a subpopulation after branching. In small populations, stochastic effects become important and we calculate the probability of subpopulation extinction. Our work elucidates the evolutionary origins of heterogeneity in local PGGs among individuals of two traits (production and neighbourhood size), and the effects of stochasticity in two-dimensional trait space, where novel effects emerge.
In this action research study of my classroom of eighth grade mathematics, I investigated the attitudes of students toward mathematics along with their achievement levels with the use of oral presentations in my Algebra class. During the second semester the class was divided into groups of two for each presentation, changing partners each time. Every other week each group was given a math problem that required more work than a normal homework type problem. On the last day of that week the students gave a short presentation on their problem. I discovered that while there was no significant evidence that student achievement increased, the students did enjoy the different aspect of presentations in a math class. I plan to implement presentations in my classroom more often with the intent to increase student enjoyment. Presentations in Mathematics
The concept that the clinical successes that are seen in individual patients can and must be replicated and scaled up to a population level if we are ever to have a world that is free of diabetes and its complications.
Background: Acinetobacter spp. are a frequent cause of nosocomial as well as community-acquired infections and represent increasingly difficult therapeutic challenges. The Tigecycline Evaluation Surveillance Trial (TEST) is monitoring global resistance patterns of significant pathogens, including multidrug resistant (MDR) Acinetobacter spp. Methods: Clinically significant Acinetobacter spp. were obtained from sites in 9 countries (China, Hong Kong, India, Indonesia, Malaysia, Singapore, S. Korea, Taiwan and Thailand). MICs for piperacillin/tazobactam (PT), levofloxacin (LVX), ceftriaxone (CAX), cefepime (CPE), amikacin (AK), minocycline (MIN), ceftazidime (CAZ), tigecycline (TIG) and imipenem (IMI, 2004-06 only) and meropenem (MER, 2006-11 only) were determined using supplied broth microdilution panels and interpreted according to CLSI and FDA guidelines. Multidrug resistance was defined as resistance to 3 or more drug families. 619 of 978 (63.3%) Acinetobacter spp. collected were determined to be MDR. Results: The % MDR, MIC90 (μg/mL), and % susceptible (S) of Acinetobacter spp. from Asia, 2004-2011, are shown in the following table:Tabled 1Year20042005200620072008200920102011N MOR2419791711025411555MIC90%SMIC90%SMIC90%SMIC90%SMIC90%SMIC90%SMIC90%SMIC90%SAK>6416.7>6415.8>6412.7>6412.9>6413.7>6411.1>6419.1>6410.9CPE>320>320>326.3>322.9>321.0>321.9>320>321.8CAZ>320>320>321.3>322.3>325.9>325.6>322.6>321.8CAX>640>640>641.3>640.6>640>640>640>640IMI>1616.7>1652.6>1612.1ntntntntntntntntntntLVX>820.8>810.5>813.9>86.4>82.9>80>82.6>83.6MERntntnt94.7878.5878.41657.01657.4859.1852.7MIN888.0494.7878.5878.41657.01657.4859.1852.7PT>1284>1280>1286.3>1284.1>1280>1283.7>1280.9>1280TIG1na1na2na2na2na2na2na2na Open table in a new tab nt- not tested; na- no breakpoint available. Conclusion: TIG exhibited the lowest MIC90 (1-2μg/mL) across all years against MDR Acinetobacter, followed by minocycline (4-16μg/mL). The percentage of MDR isolates increased significantly over the eight years of the study (p<0.0001, Cochran-Armitage trend test). This increase in resistance emphasizes the need for continual active surveillance of antibiotic efficacy in Asia.
Background: Tigecycline (TIG) has potent expanded broad spectrum activity against most commonly encountered species responsible for community and hospital acquired infections. The T.E.S.T. program determined the in vitro activity of TIG against Acinetobacter resistant to one or more of piperacillin-tazobactam (PT), levofloxacin (LVX), ceftriaxone (CAX), cefepime (CPE), amikacin (AK), minocycline (MIN), ceftazidime (CAZ), and imipenem (IMP). Study strains were collected from hospitals in the United States from 2004–2007. Methods: A total of 2,367 clinical isolates were identified to species level from participating sites and confirmed by the central laboratory. Minimum Inhibitory Concentrations (MICs) were determined by the local laboratory using supplied broth microdilution panels and interpreted according to CLSI guidelines Results: Resistance rates for comparator drugs were CAZ 42%, CAX 41%, LVX 41%, CPE 34%, PT 17%, AK 7%, MIN 7%, and IMP 2%. TIG inhibited 98% of all isolates at = 8 mcg/ml. TIG MIC50/90 for strains resistant to 0, 1, 2, 3, 4, or ≥5 drug classes were 0.12/0.5, 0.5/1, 0.5/2, 1/2, 1/2, and 1/4, respectively, demonstrating a gradual diminishment of TIG activity in strains resistant to multiple drug classes Conclusions: TIG had good in vitro activity against most Acinetobacter strains resistant to one or more other drugs in this study, although the higher TIG MICs seen for these strains suggests some linkage to resistance mechanisms for other drugs (efflux). TIG remained effective in inhibiting multi-drug resistant Acinetobacter spp., further demonstrating its wide spectrum of activity vs. drug-resistant bacteria.
Objectives: Tigecycline (TIG), a new glycylcycline, has been shown to have potent broad spectrum activity against most commonly encountered species responsible for community and hospital acquired infections. The T.E.S.T. program determined the in vitro activity of TIG and 10 comparators against bacteremia pathogens. Isolates were collected from 9 hospital sites in Australia throughout 2004–2007. Methods: 533 bacteremia isolates were identified to the species level at participating sites and confirmed by the central laboratory. MICs were determined by each site using supplied broth microdilution panels and interpreted according to CLSI guidelines. Results: Susceptibility of selected pathogens to tigecycline is summarized below. Conclusions: TIG demonstrated a broad spectrum of antimicrobial activity, including Acinetobacter spp., Enterobacteriaceae (incl. ESBL phenotypes), S. aureus (incl. MRSA), S. pneumoniae (all phenotypes), and both Van-S and Van-R Enterococcus spp. The wide spectrum of activity of tigecycline provides enhanced antimicrobial coverage of pathogens causing bacteremia.
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