Observed antagonistic effect of linezolid on daptomycin or vancomycin activity against biofilm-forming methicillin-resistant Staphylococcus aureus in an in vitro pharmacodynamic model

Pharmacodynamic activity in antibiotic combinations of daptomycin, vancomycin and linezolid was investigated in a 48h in vitro pharmacodynamic model. Using free human-simulated concentrations, activity against clinical biofilm-forming methicillin-resistant Staphylococcus aureus isolates was evaluated. Linezolid antagonized vancomycin activity at 24 and 48h. Linezolid antagonized daptomycin at 24 and 48h depending on dose and strain. Adding daptomycin increased vancomycin activity at 48h (P \u3c 0.03). These results may be strain dependent and require further clinical investigation

Simulating quantum correlations as a distributed sampling problem

It is known that quantum correlations exhibited by a maximally entangled qubit pair can be simulated with the help of shared randomness, supplemented with additional resources, such as communication, post-selection or non-local boxes. For instance, in the case of projective measurements, it is possible to solve this problem with protocols using one bit of communication or making one use of a non-local box. We show that this problem reduces to a distributed sampling problem. We give a new method to obtain samples from a biased distribution, starting with shared random variables following a uniform distribution, and use it to build distributed sampling protocols. This approach allows us to derive, in a simpler and unified way, many existing protocols for projective measurements, and extend them to positive operator value measurements. Moreover, this approach naturally leads to a local hidden variable model for Werner states.Comment: 13 pages, 2 figure

Simulation of bipartite qudit correlations

We present a protocol to simulate the quantum correlations of an arbitrary bipartite state, when the parties perform a measurement according to two traceless binary observables. We show that $\log(d)$ bits of classical communication is enough on average, where $d$ is the dimension of both systems. To obtain this result, we use the sampling approach for simulating the quantum correlations. We discuss how to use this method in the case of qudits.Comment: 7 page

Overconsumption of Antibiotics

We applaud Thomas Van Boeckel and colleagues1 for their large analysis of antibiotic consumption in 71 countries. A 36% increase in use of antibiotics worldwide, 76% of which was in Brazil, Russia, India, China, and South Africa, is a concerning finding. In Europe and the USA, practitioners are increasingly aware of the importance of infection control and antimicrobial stewardship. However, 50% of antimicrobials, irrespective of setting, are used inappropriately.2,3 We agree that most increases in global antibiotic consumption are probably caused by inappropriate use and that coordinated efforts to improve antimicrobial use internationally are desperately needed

In Vitro Activities of Telavancin and Vancomycin against Biofilm-Producing Staphylococcus aureus, S. epidermidis, and Enterococcus faecalis Strains

We investigated the activities of telavancin and vancomycin against biofilm-producing Staphylococcus and Enterococcus strains. At clinically attainable concentrations, telavancin was active against bacteria embedded in biofilm (minimal biofilm eradication concentration [MBEC], 0.125 to 2 μg/ml) and inhibited biofilm formation at concentrations below the MIC. Vancomycin did not demonstrate the same activity (MBEC, ≥512 μg/ml) against Staphylococcus aureus and Enterococcus faecalis. Telavancin may have a unique role in biofilm-associated infections

470. Concomitant Antibiotic Use and Death Among a National Cohort of Veterans With Clostridium difficile Infection (CDI)

Background: Antibiotic use is a well-known risk factor for development of CDI, and there is preliminary evidence suggesting concomitant antibiotic use may result in poor outcomes, including death. This work investigated the effect of concomitant antibiotic exposure during CDI treatment on mortality among patients with CDI. Methods: We conducted a national retrospective study of Veterans with a first CDI between 2010 and 2014, defined as a positive C. difficile toxin(s) and no episode in the year prior. Those treated with guideline recommended CDI treatment were included (10–14 days of PO or IV metronidazole, PO or PR vancomycin, or fidaxomicin). The exposure of interest was any non-CDI antibiotic use during CDI treatment; and the outcome was all cause death within 30 days of the end of CDI treatment. Inverse probability of treatment weighted Cox proportional hazards models were used to estimate the effect of concomitant antibiotic use on time to mortality. Weights were derived from propensity score modeling of the probability of exposure to antibiotics during CDI treatment as a function of potential confounders. Sensitivity analyses by antibiotic class were conducted. Results: Of the 9,517 patients included in the study cohort, mean age was 65.3 years (±SD 14.6), 92.5% (n = 8,802) were male, and 75.03% (n = 7,141) were white. Half were exposed to non-CDI antibiotics during CDI treatment (51.8%, n = 4,925) and 8.9% (n = 849) died. In unadjusted and adjusted analyses, concomitant antibiotic use was associated with death (HR 5.74, 95% CI 4.75–6.93; aHR 2.39, 95% CI 2.07–2.75). Advanced generation cephalosporin (aHR 2.36, 95% CI 2.05–2.71), β-lactam/β-lactamase inhibitor combinations (aHR 1.45, 95% CI 1.16–1.82), and clindamycin (aHR 1.95, 95% CI 1.26–3.02) were associated with death, while fluoroquinolone use was not (aHR 0.97, 95% CI 0.84–1.12) Conclusion: Among our national cohort, concomitant antibiotic use was common during CDI treatment. Any concomitant antibiotic use increased the risk of death; however, results suggest risk might vary by antibiotic class. Results support continued efforts in the reduction of unnecessary antibiotic use during CDI treatment, and future studies into which antibiotics may have the least risk of death when treatment is necessary

Clinical Implications of Vancomycin Heteroresistant and Intermediately Susceptible Staphylococcus aureus

Staphylococcus aureus (S. aureus) has proven to be a major pathogen with the emergence of methicillin-resistant S. aureus (MRSA) infections and recently with heteroresistant vancomycin-intermediate S. aureus (hVISA) and vancomycin-intermediate S. aureus (VISA) infections. Although vancomycin is traditionally a first-line and relatively effective antibiotic, its continued use is under question because reports of heteroresistance in S. aureus isolates are increasing. Both hVISA and VISA infections are associated with complicated clinical courses and treatment failures. The prevalence, mechanism of resistance, clinical significance, and laboratory detection of hVISA and VISA infections are not conclusive, making it difficult to apply research findings to clinical situations. We provide an evidence-based review of S. aureus isolates expressing heterogenic and reduced susceptibility to vancomycin

Antimicrobial Stewardship Program Prompts Increased and Earlier Infectious Diseases Consultation

A recent analysis demonstrated that infectious diseases (ID) specialty intervention was associated with decreased mortality and hospital readmission. These benefits were greatest if involvement occurred within two days of hospital admission. Antimicrobial stewardship programs should augment the services of an ID specialist team and promote formal consultation. Implementation of an antimicrobial stewardship program at the Providence Veterans Affairs Medical Center was associated with an increased number of consults (increase of 72.2%) and decreased time to consult (3.5 days sooner), which might also dramatically improve patient outcomes, including mortality and readmission rates

Activity of tobramycin and polymyxin-E against Pseudomonas aeruginosa biofilm coated medical grade endotracheal tubes.

Indwelling medical devices have become a major source of nosocomial infections; especially Pseudomonas aeruginosa (P. aeruginosa) infection, which remain the most common cause of ventilator associated pneumonia (VAP) in neonates and children. Using medical grade polyvinyl chloride endotracheal tubes (ETTs), the activity of tobramycin and polymyxin-E was quantified in a simulated prevention and treatment static time kill model using biofilm forming P. aeruginosa. The model simulated three clinical conditions: 1) planktonic bacteria in the presence of antibiotics, tobramycin and polymyxin-E, without ETTs, 2) planktonic bacteria grown in the presence of P. aeruginosa, antibiotic and ETTs (simulating prevention) and 3) a 24h formed P. aeruginosa biofilm on ETTs prior to antibiotic exposure (simulating treatment). In the model simulating prevention (conditions 1 and 2 above), tobramycin alone or in combination with polymyxin-E was more bactericidal than polymyxin-E alone at 24 hours using a concentration greater than 2 times the minimum inhibitory concentration (MIC). However, after a 24h old biofilm was allowed to form on the ETTs, neither monotherapy nor combination therapy over 24 hours exhibited bactericidal or bacteriostatic effects. Against the same pathogens, tobramycin and polymyxin-E, both alone or in combination exhibited bactericidal activity prior to biofilm attachment to the ETTs, however no activity was observed once biofilm formed on ETTs. These findings support surveillance culturing to identify pathogens for a rapid and targeted approach to therapy, especially when P. aeruginosa is a potential pathogen

Risk Factors Associated with Mupirocin Resistance in Methicillin-Resistant Staphylococcus aureus

Implementation of meticillin-resistant Staphylococcus aureus (MRSA) decolonisation programmes has been increasing and the emergence of mupirocin resistance has been reported. However, the patient-level risk factors associated with mupirocin resistance are not clear. In this study, independent predictors of mupirocin resistance in MRSA among Providence Veterans Affairs Medical Center patients with MRSA-positive culture dates between 1 July 2004 and 30 June 2008 were identified using a frequency-matched case–control study. Forty cases (mupirocin-resistant) were matched on culture date quarter and year to 270 controls (mupirocin-susceptible). The adjusted conditional logistic regression model identified three significant independent predictors associated with mupirocin resistance in MRSA: (1) exposure to mupirocin in the year prior to the culture date [odds ratio (OR): 9.84; 95% confidence interval (CI): 2.93–33.09]; (2) Pseudomonas aeruginosa infection in the year before the culture-related admission (4.85; 1.20–19.61); and (3) cefepime use in the year prior to culture (2.80; 1.03–7.58). In sensitivity analyses, previous mupirocin exposure was associated with low-level [minimum inhibitory concentration (MIC) 8–128 mg/L; 23 cases, 202 controls; OR: 6.32; 95% CI: 1.58–25.33] and high-level (MIC ≥256 mg/L; 17 cases, 151 controls; OR: 11.18; 95% CI: 1.89–66.30) mupirocin resistance. To our knowledge, this is the first case–control study to reveal a strong association between previous mupirocin exposure and subsequent mupirocin resistance in MRSA, with demonstrated robustness in low- and high-level mupirocin resistance. Mupirocin susceptibility monitoring is critical for facilities instituting decolonisation with mupirocin as increased use may reduce effectiveness through resistance