Management of serious meticillin-resistant Staphylococcus aureus infections: what are the limits?

Severe (life-threatening) meticillin-resistant Staphylococcus aureus (MRSA) infection continues to be treated with vancomycin despite accumulating evidence of poor outcome, increasing resistance and unachievable pharmacokinetic/pharmacodynamic (PK/PD) targets. The minimum inhibitory concentration (MIC) susceptibility breakpoint for vancomycin was recently reduced to 2 mg/L. Whilst the great majority of clinical isolates are thus still classified as susceptible, the available clinical evidence argues for a method-dependent breakpoint of 0.5 mg/L (broth dilution) or 1.0 mg/L (Etest), which would classify many strains as resistant, or at best intermediate. However, automated susceptibility testing systems are not currently capable of performing accurately at this low level, and such low breakpoints are unsatisfactory because the poor reproducibility of tests (plus or minus one doubling dilution) results in a critical non-reproducibility around the modal MIC of 1 mg/L described in most published data. Therefore, vancomycin should be used with caution in severe (life-threatening) staphylococcal disease and the MIC should always be reported by method. Daptomycin is generally preferred for bacteraemia/endocarditis and linezolid for pneumonia. Better outcome data for vancomycin, based on achievable PK/PD targets and using robust MIC tests, are urgently required.     

Increase in the prevalence of Panton–Valentine leukocidin and clonal shift in community-onset methicillin-resistant Staphylococcus aureus causing skin and soft-tissue infections in the Rhine-Neckar Region,Germany, 2012–2016

Methicillin-resistant Staphylococcus aureus (MRSA) remains a major challenge for patient care. Community-associated (CA)-MRSA often have a fitness and virulence advantage compared with their nosocomial counterparts. Increased mobility, travel activities and migration accelerate the intercontinental spread of virulent CA-MRSA strains. Outpatient clinics are the most important route of entry for CA-MRSA into hospitals. However, systematic data on CA-MRSA in Germany are limited. In this study, community-onset (CO)-MRSA skin and soft-tissue infection (SSTI) isolates in the Rhine-Neckar Region from 2012–2016 were characterised to gain an insight into their molecular epidemiology and to monitor potential introduction of virulent and dominant MRSA strains into our hospital. A total of 2475 patients with S. aureus SSTI were identified in the outpatient departments of our hospital, of which 94 (3.8%) were MRSA. In addition, 40.4% of the CO-MRSA harboured the virulence factor Panton–Valentine leukocidin (PVL). ST8-t008-MRSA-IVa/c (23.7%; 9/39) and ST80-t044-MRSA-IVc (15.8%; 6/38) were the predominant PVL-positive MRSA. Molecular typing and epidemiological data revealed that 42.6% (40/94) of strains could be traced back to a local origin and 44.7% (42/94) were endemic outside of Europe. Resistance to quinolones, clindamycin and macrolides was common, whilst resistance to trimethoprim/sulfamethoxazole, tetracycline, mupirocin, chlorhexidine and fusidic acid was low. No resistance to rifampicin, fosfomycin or linezolid was observed. This study provides insight into the clonal composition of CO-MRSA in the Rhine-Neckar Region. The increase of PVL-positive MRSA and the introduction of imported strains may affect the local MRSA landscape in the near future and should be monitored closely.     

The use of ceftolozane-tazobactam in the treatment of complicated intra-abdominal infections and complicated urinary tract infections—A meta-analysis of randomized controlled trials

ObjectiveThe aim of this study was to assess the clinical efficacy and safety of ceftolozane-tazobactam in the treatment of complicated intra-abdominal infections (cIAIs) and complicated urinary tract infections (cUTIs) in adult patients through meta-analysis.MethodsPubMed, Embase and Cochrane databases were searched up to June 2019. Only randomized controlled trials (RCTs) that evaluated ceftolozane-tazobactam and comparators for treating cIAIs and cUTIs in adult patients were included. Primary outcome was clinical cure rate; secondary outcomes were clinical failure rate, microbiological eradication rate, and risk of an adverse event (AE).ResultsThree RCTs were included. Overall, ceftolozane-tazobactam had a clinical cure rate similar to comparators in the microbiological intent-to-treat (mITT) population (odds ratio [OR], 0.87; 95% confidence interval [CI], 0.43–1.79; I² = 73%) and in the clinically evaluable (CE) population (OR, 1.22; 95% CI, 0.79–1.88; I² = 0%). Furthermore, ceftolozane-tazobactam had a similar microbiological eradication rate for pathogens (OR, 1.31; 95% CI, 0.42–4.10; I² = 37%). There were no significant differences in the risks of treatment-emergent AEs (OR, 1.04; 95% CI, 0.87–1.23; I² = 0%), serious AEs (OR, 1.16; 95% CI, 0.67–1.99; I² = 37%), discontinuation of study drug due to an AE (OR, 0.77; 95% CI, 0.17–3.47) and mortality (OR, 1.62; 95% CI, 0.69–3.77, I² = 0%) between ceftolozane-tazobactam and comparators.ConclusionsThe clinical efficacy of ceftolozane-tazobactam is as high as that of comparators in the treatment of cIAIs and cUTIs in adult patients, and this antibiotic is well tolerated.     

Efficacy and safety of ceftazidime–avibactam versus imipenem–cilastatin in the treatment of complicated urinary tract infections,including acute pyelonephritis,in hospitalized adults: results of a prospective,investigator-blinded,randomized study

Abstract

Objectives:

The aim of this prospective phase II, randomized, investigator-blinded study (NCT00690378) was to compare the efficacy and safety of ceftazidime–avibactam and imipenem–cilastatin in hospitalized adults with serious complicated urinary tract infection (cUTI) due to Gram-negative pathogens.     

The role of tazobactam-based combinations for the management of infections due to extended-spectrum β-lactamase-producing Enterobacterales: Insights from the Society of Infectious Diseases Pharmacists

Extended-spectrum β-lactamase (ESBL)-producing Enterobacterales are a global threat to public health due to their antimicrobial resistance profile and, consequently, their limited available treatment options. Tazobactam is a sulfone β-lactamase inhibitor with in vitro inhibitory activity against common ESBLs in Enterobacterales, including CTX-M. However, the role of tazobactam-based combinations in treating infections caused by ESBL-producing Enterobacterales remains unclear. In the United States, two tazobactam-based combinations are available, piperacillin-tazobactam and ceftolozane-tazobactam. We evaluated and compared the roles of tazobactam-based combinations against ESBL-producing organisms with emphasis on pharmacokinetic/pharmacodynamic exposures in relation to MIC distributions and established breakpoints, clinical outcomes data specific to infection site, and considerations for downstream effects with these agents regarding antimicrobial resistance development. While limited data with ceftolozane-tazobactam are encouraging for its potential role in infections due to ESBL-producing Enterobacterales, further evidence is needed to determine its place in therapy. Conversely, currently available microbiologic, pharmacokinetic, pharmacodynamic, and clinical data do not suggest a role for piperacillin-tazobactam, and we caution clinicians against its usage for these infections.     

Reduced glycopeptide and lipopeptide susceptibility in Staphylococcus aureus and the “seesaw effect”: Taking advantage of the back door left open?

Methicillin-resistant S. aureus (MRSA) constitutes approximately 50% of clinical S. aureus isolates and is most commonly the result of production of a mutated pencillin-binding protein, PBP2a, which is able to carry out essential cell wall synthesis functions while maintaining a low-affinity for nearly all beta-lactam antibiotics. Decreased susceptibility to glycopeptides, typically considered first-line MRSA agents, has also been documented. Interestingly, among MRSA isolates, an increase in beta-lactam susceptibility has been documented in the presence of declining lipo- and glycopeptide susceptibility. This phenomenon, termed the “seesaw effect” has been documented both in vitro and in vivo. In the era of increasing antimicrobial resistance and few new drugs to treat these organisms, this phenomenon may provide novel ways to use our current antimicrobials in a new, and more effective, manner.     

Effectiveness and safety of vildagliptin and vildagliptin add-on to metformin in real-world settings in Egypt – results from the GUARD study

Objective: The GUARD study evaluated the effectiveness, safety, and tolerability of vildagliptin treatment with or without metformin in patients with type 2 diabetes mellitus (T2DM) in real-life settings. Here we present the results of the GUARD study for the patient subset from Egypt.

Research design and methods: This was a 24?±?6 weeks, prospective, non-interventional study that enrolled adult patients with T2DM receiving vildagliptin or vildagliptin?+?metformin combination therapy as per local prescribing information.

Main outcome measures: The primary effectiveness endpoint was change in HbA1c levels from baseline to week 24?±?6 endpoint. Safety was assessed by reporting of adverse events and serious adverse events (SAEs).

Results: Of 2786 patients enrolled from Egypt, 655 received vildagliptin and 2131 received vildagliptin?+?metformin. Overall, at baseline, mean (± standard deviation [SD]) age was 49.5?±?9.49 years, BMI was 31.5?±?4.85?kg/m², HbA1c was 8.4?±?0.86%, and duration of T2DM was 2.3?±?3.78 years. At week 24, significant reductions in mean (±SD) HbA1c were observed in the vildagliptin (?1.47?±?0.79%) and vildagliptin?+?metformin (?1.62?±?0.82%) groups (both p?Conclusion: In a real-world setting, vildagliptin, with or without metformin, resulted in significant reductions in HbA1c and was well tolerated in patients with T2DM from Egypt. Limitations of the study include non-randomization and the open-label, observational nature of the study.     

Effectiveness of adjunctive gabapentin in resistant bipolar disorder: is it due to anxious-alcohol abuse comorbidity?

We evaluated effectiveness and predictors of response of gabapentin (GBP) as adjunctive treatment in a sample of 43 subjects with DSM-III-R bipolar disorder who were resistant to standard mood stabilizers. Diagnostic evaluation was performed by means of the Semistructured Interview for Mood Disorder. Clinical evaluation was performed at the beginning and end of the observation period by means of the Hamilton Rating Scale for Depression (HAM-D), the Young Mania Rating Scale, and the Clinical Global Impression Scale. GBP was administered as an adjunctive treatment for an 8-week period in combination with other mood stabilizers, benzodiazepines, antidepressants, and neuroleptics. Mean dosage +/- SD at week 8 was 1270 +/- 561.4 mg (range, 600-2400 mg). Adjunctive treatment with GBP was well tolerated by almost all the subjects; only three patients had to interrupt treatment before week 8, two because of inefficacy and one because of the appearance of side effects (ataxia and irritability); in other patients, the most frequent side effects were sedation, irritability, tremor, ataxia or motor instability, and nausea. Eighteen (41.9%) of 43 patients who began treatment were considered responders. Mean total HAM-D score showed a significant reduction during the 8 weeks of treatment. Analysis of the various HAM-D dimensions showed that the anxiety-somatization factor was the one with the greatest change. Seventeen of the 18 responder patients remained in remission for a period ranging from 4 to 12 months without clinically significant side effects or adverse events. One patient had to interrupt GBP treatment and be administered neuroleptics because of the reappearance of manic symptoms. Regarding response predictors, logistical regression analysis showed that the presence of panic disorder and alcohol abuse was associated with positive response. The results of the present study replicate prior studies indicating that GBP is an effective and well tolerated treatment in a large proportion of bipolar patients who are resistant to traditional mood stabilizers. More specifically, this drug appears to have antidepressant and anxiolytic properties. What is new in the present report is the suggestion that the utility of GBP in resistant bipolar disorder resides in its effectiveness against comorbid panic disorder and alcohol abuse.     

Bactericidal activity of daptomycin versus vancomycin in the presence of human albumin against vancomycin-susceptible but tolerant methicillin-resistant Staphylococcus aureus (MRSA) with daptomycin minimum inhibitory concentrations of 1–2 μg/mL

This study explored the influence of vancomycin tolerance and protein binding on the bactericidal activity of vancomycin versus daptomycin (protein binding 36.9% vs. 91.7%, respectively) against four vancomycin-tolerant methicillin-resistant Staphylococcus aureus (MRSA) [minimum inhibitory concentration/minimum bactericidal concentration (MIC/MBC) = 0.5/16, 1/32, 2/32 and 1/32 μg/mL for vancomycin and 1/1, 1/2, 2/2 and 2/4 μg/mL for daptomycin]. Killing curves were performed with vancomycin/daptomycin concentrations equal to serum peak concentrations (C_max) (65.70/98.60 μg/mL) and trough concentrations (C_min) (7.90/9.13 μg/mL) in the presence and absence of a physiological human albumin concentration (4 g/dL), controlled with curves with the theoretical free drug fraction of vancomycin/daptomycin C_max (41.45/8.18 μg/mL) and C_min (4.98/0.76 μg/mL). Vancomycin C_max and C_min concentrations, regardless of the media, showed a bacteriostatic profile not reaching a reduction of 99% or 99.9% of the initial inocula during the 24-h experimental time period. Daptomycin antibacterial profiles significantly differed when testing C_max and C_min. C_max was rapidly bactericidal (≤4 h) with >5 log₁₀ reduction in the initial inocula for all strains, regardless of the presence or not of albumin or the use of concentrations similar to free C_max. C_min exhibited similar final colony counts at 0 h and 24 h in curves with albumin, but with >3 log colony-forming units (CFU)/mL reduction at ≤4 h for strains with an MIC of 1 μg/mL and ca. 2 log CFU/mL reduction at ≤6 h for strains with an MIC of 2 μg/mL. This activity was significantly higher than the activity of the free C_min fraction. The results of this study reinforce the idea that pharmacodynamics using concentrations calculated using reported protein binding are unreliable. Daptomycin exhibited rapid antibacterial activity against vancomycin-tolerant MRSA isolates even against those with high daptomycin MICs in the presence of physiological albumin concentrations.     

Panton-Valentine leukocidin-producing methicillin-Sensitive Staphylococcus aureus as a cause for recurrent, contagious skin infections in young, healthy travelers returned from a tropical country: a new worldwide public health problem?

Skin infections associated with visits to tropical countries are well known. In most of the cases, the infection is caused by Staphylococcus aureus . After a sufficient antibiotic treatment, the skin infections resolve without any sequelae. But several patients suffer from recurrent skin infections. Panton-Valentine leukocidin (PVL) is a cytotoxin produced by S aureus , which is associated with severe necrotic skin lesions and with a high contagiosity.     

Modelling the changes due to the endothelium and hypertension in the α-adenoreceptor-mediated responses of rat aorta

1 The present study focuses on the role of endothelium on α₁-adrenoceptor-mediated vasoconstriction in aorta from Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR). To define and quantify changes in the parameters governing agonism at α₁-adrenoceptor by hypertension and/or endothelium, the operational model of analysis was used. 2 In either endothelium intact or denuded aorta, the sensitivity (P < 0.001) and the maximum contraction (P < 0.05) to phenylephrine were smaller in SHR than in WKY. 3 However, in each strain of rats, removal of endothelium increased the sensitivity (P < 0.001) to phenylephrine but reduced (P < 0.05) KCl-evoked vasoconstriction, suggesting a modulation of these responses by the endothelium. The observed differences in sensitivity and maximum contraction are interpreted in terms of the operational parameters: E_m, the maximum possible effect; pK_A, the agonist affinity; α, the agonist efficacy and n, the slope for the function relating receptor occupancy to pharmacological effect. The estimated parameters reflected differences, between strains, in the signal transduction processes linked to α₁-adrenoceptor stimulation ascribed to the presence of the endothelium. 4 N^G-nitro- l -arginine methyl ester (L-NAME), enhanced to a similar extend in both rat strains the sensitivity (P < 0.001) and the maximum contraction to phenylephrine. Indomethacin reduced the maximum contraction to phenylephrine by 56.85% in SHR and by 11.80% in WKY suggesting that contracting prostanoids play a more major role in this response in SHR than in WKY. Nevertheless, these inhibitors were without effect on denuded vessels from both strains suggesting that NO and cyclooxygenase products from the media or the adventitia do not play a role on the phenylephrine-mediated responses. 5 The studied endothelial factors partially explain the observed differences in modulation of α₁-adrenoceptor responses by the endothelium but suggest the participation of other compounds released by the endothelium.     

Penetration of nanoparticles and nanomaterials in the skin: Fiction or reality?

The advent of nanotechnological products in the market, while holding great promise, is raising concerns in consumers. Therefore, this contribution will attempt to compare different particulate formulations and to answer whether their passive penetration into, and potential permeation through the skin may be possible or not. To this end, skin structure, composition, and penetration paths will be concisely reviewed. Parameters generally cited to affect skin absorption will be resumed and commented on from the perspective of potentially penetrating nanosized agents. These sections will provide the basis to understand what is fiction and what is reality. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:21–50, 2010     

ReoPro rules: results from the ‘Do Tirofiban and ReoPro Give Similar Efficacy Trial’ (TARGET)

In the treatment of atherosclerotic disease, stenting in the presence of a glycoprotein (GP) IIb/IIIa antagonist is becoming an increasingly common procedure. The ‘Do Tirofiban and ReoPro Give Similar Efficacy Trial’ (TARGET) was designed to determine whether the cheaper tirofiban was as effective and safe as abciximab in the prevention of ischaemic events with stenting. Unexpectedly, abciximab was shown to be superior to tirofiban. Tirofiban is a selective GP IIb/IIIa antagonist whereas abciximab has additional anti-inflammatory actions, which may contribute to its superiority.     

Treatment of patients with serious infections due to carbapenem-resistant Acinetobacter baumannii: How viable are the current options?

This review critically appraises the published microbiologic and clinical data on the treatment of patients with carbapenem-resistant Acinetobacter baumannii infections. Despite being recognized as an urgent threat pathogen by the CDC and WHO, optimal treatment of patients with serious CRAB infections remains ill-defined. Few commercially available agents exhibit reliable in vitro activity against CRAB. Historically, polymyxins have been the most active agents in vitro, though interpretations of susceptibility data are difficult given issues surrounding MIC testing methodologies and lack of correlation between MICs and clinical outcomes. Most available preclinical and clinical data involve use of polymyxins, tetracyclines, and sulbactam, alone and in combination. As the number of viable treatment options is limited, combination therapy with a polymyxin is often used for patients with CRAB infections, despite the significant risk of nephrotoxicity. However, no treatment regimen has been found to reduce mortality, which exceeds 40% across most studies, or substantially improve clinical response. While some newer agents, such as eravacycline and cefiderocol, have demonstrated in vitro activity, clinical efficacy has not been fully established. New agents with clinically relevant activity against CRAB isolates and favorable toxicity profiles are sorely needed.