Update of dalbavancin spectrum and potency in the USA: report from the SENTRY Antimicrobial Surveillance Program (2011)

Dalbavancin Activity When Tested against Streptococcus pneumoniae Isolated in Medical Centers on Six Continents (2011 to 2014)

Dalbavancin, a novel lipoglycopeptide, was approved for use in 2014 by regulatory agencies in the United States and Europe for the treatment of skin and skin structure infections. The activity of dalbavancin was also widely assessed by determination of its activity against Streptococcus pneumoniae clinical isolates collected from patients on six continents monitored during two time intervals (2011 to 2013 and 2014). A total of 18,186 pneumococcal isolates were obtained from 49 nations and submitted to a monitoring laboratory as part of the SENTRY Antimicrobial Surveillance Program for reference susceptibility testing. The potency of dalbavancin against S. pneumoniae was consistent across the years that it was monitored, with the MIC50 and MIC90 being 0.015 and 0.03 μg/ml, respectively, and all isolates were inhibited by ≤0.12 μg/ml. The activity of dalbavancin was not adversely influenced by nonsusceptibility to β-lactams (ceftriaxone or penicillin), macrolides, clindamycin, fluoroquinolones, or tetracyclines or multidrug resistance (MDR). Regional variations in dalbavancin activity were not detected, but S. pneumoniae strains isolated in the Asia-Pacific region were more likely to be nonsusceptible to penicillin and ceftriaxone as well as to be MDR than strains isolated in North or South America and Europe. Direct comparisons of potency illustrated that dalbavancin (MIC50 and MIC90, 0.015 and 0.03 μg/ml, respectively) was 16-fold or more active than vancomycin (MIC50, 0.25 μg/ml), linezolid (MIC50, 1 μg/ml), levofloxacin (MIC50, 1 μg/ml), ceftriaxone (MIC90, 1 μg/ml), and penicillin (MIC90, 2 μg/ml). In conclusion, dalbavancin had potent and consistent activity against this contemporary (2011 to 2014) collection of S. pneumoniae isolates.

Reversing resistance: The next generation antibacterials

Irrational antibiotic usage has led to vast spread resistance to available antibiotics, but we refuse to slide back to “preantibiotic era.” The threat is serious with the “Enterococcus, Staphylococcous, Klebsiella, Acinetobacter, Pseudomonas and Enterobacter” organisms causing nosocomial infections that are difficult to treat because of the production of extended spectrum β-lactamases, carbapenamases and metallo-β-lactamases. Facing us is a situation where soon multidrug resistance would have spread across the globe with no antibiotics to withstand it. The infectious disease society of America and Food and Drug Administration have taken initiatives like the 10 × ‘20 where they plan to develop 10 new antibiotics by the year 2020. Existing classes of antibiotics against resistant bacteria include the carbapenems, oxazolidinones, glycopeptides, monobactams, streptogramins and daptomycin. Newer drugs in existing classes of antibiotics such as cephalosporins, aminoglycosides, tetracyclines, glycopeptides and β-lactamase inhibitors continue to get synthesized. The situation demands newer targets against bacterial machinery. Some of them include the peptidoglycantransferase, outer membrane protein of Pseudomonas, tRNA synthase, fatty acid synthase and mycobacterial ATP synthase. To curb the irrational and excessive usage of presently available antibiotics should be a priority if they are still to be kept in usage for the future.

Dalbavancin (BI-387) for the treatment of complicated skin and skin structure infection

In the era of increasing antibiotic resistance, development of new agents that could provide therapeutic options for difficult to treat pathogens is vital. Dalbavancin is a new lipoglycopeptide recently approved by the US FDA for the treatment of acute bacterial skin and skin structure infections. A derivative of the older glycopeptide class, chemical structure alterations resulted in a molecule with a similar mechanism of action, however, with a comparatively increased activity as reflected by organism MICs. These modifications also resulted in an antibiotic with distinctive properties that allow for once-weekly dosing in the treatment of Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus and drug resistant Streptococcus spp. As the first of these long acting compounds, understanding the pharmacokinetic and pharmacodynamic properties of agents like dalbavancin is essential for determining a place in therapy.

New Gram-Positive Agents: the Next Generation of Oxazolidinones and Lipoglycopeptides

The growing problem of antimicrobial resistance among bacterial pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), has reached a critical state. Tedizolid phosphate, dalbavancin, and oritavancin have recently been approved by the U.S. Food and Drug Administration (FDA) for the treatment of acute bacterial skin and skin structure infections (ABSSSI) and represent the next generation of oxazolidinones and lipoglycopeptides. All three agents exhibit in vitro activity and clinical efficacy against MRSA. Tedizolid phosphate and oritavancin demonstrate in vitro activity against VRE. These new Gram-positive agents are reviewed here.

Investigation of Linezolid Resistance in Staphylococci and Enterococci

The objective of this study was to investigate an apparent increase in linezolid-nonsusceptible staphylococci and enterococci following a laboratory change in antimicrobial susceptibility testing from disk diffusion to an automated susceptibility testing system. Isolates with nonsusceptible results (n = 27) from Vitek2 were subjected to a battery of confirmatory testing which included disk diffusion, Microscan broth microdilution, Clinical and Laboratory Standards Institute (CLSI) reference broth microdilution, gradient diffusion (Etest), 23S rRNA gene sequencing, and cfr PCR. Our results show that there is poor correlation between methods and that only 70 to 75% of isolates were confirmed as linezolid resistant with alternative phenotypic testing methods (disk diffusion, Microscan broth microdilution, CLSI broth microdilution, and Etest). 23S rRNA gene sequencing identified mutations previously associated with linezolid resistance in 16 (59.3%) isolates, and the cfr gene was detected in 3 (11.1%) isolates. Mutations located at positions 2576 and 2534 of the 23S rRNA gene were most common. In addition, two previously undescribed variants (at positions 2083 and 2345 of the 23S rRNA gene) were also identified and may contribute to linezolid resistance.

New developments in the treatment of acute bacterial skin and skin structure infections: considerations for the effective use of dalbavancin

Dalbavancin, an intravenous glycopeptide, was approved by the US Food and Drug Administration in May 2014 for use in adult patients with acute bacterial skin and skin structure infections. The recommended dosing regimen for effective use of dalbavancin is 1,000 mg followed by a 500 mg dose after 1 week. Two multinational, identically designed, non-inferiority trials, DISCOVER 1 and 2, demonstrated similar early clinical success with dalbavancin compared to vancomycin with an option to switch to oral linezolid. In a recently published non-inferiority trial, a single-dose regimen of dalbavancin was compared to the traditional two-dose administration and was found to have a non-inferior clinical response. In the aforementioned trials, dalbavancin was well tolerated, with patients experiencing transient adverse events of mild to moderate severity. The prolonged half-life, excellent skin and soft tissue penetration, bactericidal activity against Gram-positive bacteria including methicillin-resistant Staphylococcus aureus, and convenient dosing make dalbavancin a reasonable option for the treatment of acute bacterial skin and skin structure infections in adult patients who have tried and failed other therapies.

Safety profiles of old and new antimicrobials for the treatment of MRSA infections

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent cause of severe nosocomial and community-acquired infections. Various adverse effects have been associated with compounds that are commonly used in the treatment of MRSA.

AREAS COVERED

Prolonged use of high-dose vancomycin has been linked with nephrotoxicity. Linezolid use has been associated with lactic acidosis in regimens longer than 14 days and occurrence of thrombocytopenia in patients with renal impairment. Daptomycin use correlates with reversible and often asymptomatic myopathy. Among new compounds, telavancin has shown increased toxicity compared to vancomycin, especially in patients with severe renal impairment, while a low rate of adverse effects was reported others glycolipopeptides such as dalbavancin and oritavancin and for new cephalosporins. Recently studied oxazolidinones (tedizolid and radezolid) also showed mild adverse effects in Phase 2 and 3 clinical trials.

EXPERT OPINION

Due to the constant increase in antimicrobial resistance, the use of higher doses and prolonged regimens of antibiotics employed in the treatment of Gram-positive infections has become more common and linked to increased toxicity. Furthermore, new compounds with MRSA activity have been recently approved and will be regularly employed in clinical practice. The knowledge of the adverse effects and risk factors for the development of toxicity associated with anti-MRSA antimicrobials is paramount for the correct use of old and new compounds, especially in the treatment of severe infections.

In vitro activity of dalbavancin and five comparator agents against common and uncommon Gram-positive organisms isolated from cancer patients

Dalbavancin is a long acting, bactericidal lipoglycopeptide. Its in vitro activity was compared with that of vancomycin, daptomycin, linezolid, trimethoprim/sulfamethoxazole (TMP/SMX) and levofloxacin against 241 Gram-positive organisms isolated from cancer patients. The rank order of potency for the glycopeptides based on MIC90 (μg ml(-1)), that is, the concentration of antimicrobial agent required to inhibit 90% of isolates tested was dalbavancin (0.12 μg ml(-1))>daptomycin (1.0 μg ml(-1))>vancomycin (2.0 μg ml(-1)) for coagulase-negative staphylococci and Staphylococcus aureus isolates (including methicillin-susceptible (MSSA) and methicillin-resistant (MRSA) strains). Dalbavancin had potent activity against staphylococcal isolates with vancomycin MICs⩾1.0 μg ml(-1). TMP/SMX also had potent activity against staphylococci including methicillin-resistant strains, whereas levofloxacin had moderate to poor anti-staphylococcal activity. Dalbavancin also exhibited more potent activity than vancomycin and daptomycin against Bacillus spp., Corynebacterium spp., Micrococcus spp. and various streptococci (including Streptococcus pneumoniae, viridans group streptococci (VGS), beta-hemolytic streptococci and gamma-hemolytic streptococci). MBC determinations showed that dalbavancin had potent bactericidal activity against MRSA with no tolerance being detected. These data suggest that dalbavancin may be considered as an alternative to vancomycin, especially in institutions wherein a substantial proportion of infections are caused by organisms with vancomycin MICs⩾1.0 μg ml(-1).

Impact of Glycopeptide Resistance in Staphylococcus aureus on the Dalbavancin In Vivo Pharmacodynamic Target

Dalbavancin is a novel lipoglycopeptide with activity against Staphylococcus aureus, including glycopeptide-resistant isolates. The in vivo investigation reported here tested the effects of this antibiotic against seven S. aureus isolates with higher MICs, including several vancomycin-intermediate strains. Results of 1-log kill and 2-log kill were achieved against seven and six of the isolates, respectively. The mean free-drug area under the concentration-time curve (fAUC)/MIC values for net stasis, 1-log kill, and 2-log kill were 27.1, 53.3, and 111.1, respectively.

Dalbavancin: A Novel Lipoglycopeptide Antibiotic with Extended Activity Against Gram-Positive Infections

Dalbavancin is a lipoglycopeptide antibiotic recently approved by the United States Food and Drug Administration (FDA) for acute bacterial skin and skin structure infections (ABSSSIs). It is active against gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA), and minimum inhibitory concentrations (MICs) are consistently <0.125 µg/ml, much lower than most other anti-MRSA agents. Dalbavancin possesses an extended half-life of over 1 week, allowing an initial dose of 1000 mg followed by 500 mg 1 week later to complete a course of therapy for ABSSSI. It is approximately 95% protein bound and is widely distributed throughout the body, achieving concentrations similar to plasma levels in numerous tissues. Against MRSA, dalbavancin is 4–8 times more potent than vancomycin in vitro, and limited data suggest it possesses activity against MRSA with reduced susceptibility to vancomycin such as hVISA and VISA. Dalbavancin also possesses in vitro activity against streptococci and enterococci, although activity against vancomycin-resistant enterococci is lacking. In phase 3 ABSSSI studies, dalbavancin demonstrated similar activity to vancomycin and provides a more convenient dosing regimen. Limited phase 2 data suggest dalbavancin also possesses activity in catheter-related bloodstream infections. Potential further therapeutic uses include conditions that require long-term treatment such as osteomyelitis and infective endocarditis, although data are currently lacking. The extended half-life of dalbavancin, along with its in vitro activity against gram-positive organisms with reduced susceptibility to other anti-MRSA antibiotics, suggest it could have an exciting clinical role going forward.

Dalbavancin for the treatment of acute bacterial skin and skin structure infections

INTRODUCTION

Acute bacterial skin and skin structure infections (ABSSSI) have increased in incidence and severity. The involvement of resistant organisms, particularly methicillin-resistant Staphylococcus aureus, presents additional challenges. The lipoglycopeptide dalbavancin has a prolonged half-life, high protein binding, and excellent tissue levels which led to its development as a once-weekly treatment for ABSSSI. In the pivotal DISCOVER 1 and DISCOVER 2 trials, dalbavancin proved non-inferior to vancomycin followed by linezolid when used sequentially for ABSSSI, forming the basis for its recent approval in the US and Europe for ABSSSI.

AREAS COVERED

A literature search of published pharmacologic and clinical data was conducted to review the chemistry, pharmacodynamics, and pharmacokinetics of dalbavancin. We also discuss its development process, highlighting efficacy and safety data from pertinent clinical trials and the role it could play in the current clinical landscape.

EXPERT OPINION

DISCOVER 1 and DISCOVER 2 demonstrated dalbavancin's non-inferiority to vancomycin followed by linezolid for ABSSSI and confirmed its safety and tolerability. They were among the first trials to use new, early primary efficacy endpoints, and dalbavancin was among the first agents designated a Qualified Infectious Disease Product for expedited review. Dalbavancin may prove to be a valuable option for ABSSSI patients in whom conventional therapy is limited.

What's new in the treatment of serious MRSA infection?

PURPOSE OF REVIEW

Vancomycin has been the cornerstone of treatment for methicillin-resistant Staphylococcus aureus (MRSA) infections. This review describes new MRSA-active antibiotics that have recently been introduced and highlights emerging resistance.

RECENT FINDINGS

Elevations in the vancomycin minimum inhibitory concentration within the susceptible range are associated with treatment failure and mortality in the treatment of MRSA infections. Ceftaroline and ceftobiprole are anti-MRSA cephalosporins and are noninferior to comparator agents in the treatment of acute bacterial skin and skin structure infections (ABSSSIs) and pneumonia. Tedizolid is more potent than linezolid, has improved pharmacokinetics and reduced toxicity and is active against cfr-containing S. aureus. Telavancin now has approval for treatment of hospital-acquired pneumonia, and recent phase 2 trial data showed similar cure rates in S. aureus bacteremia. Dalbavancin and oritavancin are administered once weekly and are noninferior to comparators for acute bacterial skin and skin structure infections. Resistance has emerged against many new anti-MRSA antimicrobials including ceftaroline. Combination therapy of β-lactams with vancomycin or daptomycin is increasing.

SUMMARY

Several new MRSA-active agents are now approved for use, although much of the data is derived from treatment of acute bacterial skin and skin structure infections or pneumonia. Further studies are required for more invasive infections, such as bacteremia and endocarditis.

Pharmacokinetics, Safety and Tolerability of Single Dose Dalbavancin in Children 12-17 Years of Age

BACKGROUND

Dalbavancin is a lipoglycopeptide antibiotic with Gram-positive activity and novel pharmacokinetic (PK) properties that result in a prolonged terminal half-life of 15.5 days in adults. Once weekly dosing in adults in phase 3 studies of complicated skin and skin structure infections documented dalbavancin exposures associated with clinical and microbiologic efficacy. PK properties have not been examined in children. The primary objective of this open-label, multicenter single-dose phase 1 study was to characterize the PK of dalbavancin in hospitalized pediatric subjects 12-17 years of age.

METHODS

A single dose of 1000 mg of dalbavancin (the standard adult dose) was administered as a 30-minute intravenous infusion to subjects weighing 60 kg or greater and 15 mg/kg for subjects weighing <60 kg. A noncompartmental PK analysis was performed.

RESULTS

The apparent terminal t1/2 was approximately 9 days and was similar for dalbavancin dosages of 1000 mg and 15 mg/kg. Median dalbavancin plasma exposures (Cmax and AUCinf) when administered as 1000 mg to subjects weighing 60 kg or greater were similar to those when dalbavancin was administered at 15 mg/kg to subjects weighing <60 kg and slightly lower than exposures in adults given 1000 mg in prior PK and treatment studies. Single dose dalbavancin was well tolerated.

CONCLUSIONS

Given dalbavancin exposures documented in children 12-17 years of age, and recognized dose proportionality, appropriate dosing can be modeled for pediatric phase 3 trials in acute bacterial skin and skin structure infections, to achieve the same exposure that is reported to be safe and effective in adults.

The times they are a-changin': new antibacterials for skin and skin structure infections

Twenty-one agents are approved by the US Food and Drug Administration (FDA) for the therapy of skin and soft tissue infections. Of these, the five newest agents, tedizolid, telavancin, oritavancin, dalbavancin, and ceftaroline, are active against and "non-inferior" to vancomycin against methicillin-resistant Staphylococcus aureus (MRSA). Oritavancin is indicated as a single-dose intravenous regimen, while dalbavancin is a two-dose intravenous regimen given 1 week apart. Telavancin has multiple mechanisms of action. A 6-day regimen of once-daily intravenous or oral dose of tedizolid was compared with 10 days of linezolid and found to be "non-inferior" and have fewer side effects. Ceftaroline has not only MRSA activity but also activity against Escherichia coli and Klebsiella spp. We review the spectra of activity of these new agents, their clinical trials and their therapeutic efficacy, noting differences in their dosing schedules, in vitro activities and costs as potential determinants for appropriate utilization.

Use of vancomycin as a surrogate for dalbavancin in vitro susceptibility testing: results from the DISCOVER studies

Background

Dalbavancin is a lipoglycopepetide antibiotic with activity against gram positive pathogens recently approved for treatment of acute bacterial skin and skin structure infections. Pending the introduction of antimicrobial susceptibility tests, we examined the utility of vancomycin inhibitory concentrations to predict dalbavancin susceptibility in a panel of isolates obtained from phase 3 registration studies.

Findings

99.6% of Staphylococcus aureus and 99.0% of beta-hemolytic streptococci which are susceptible to vancomycin will have an MIC at or below the US FDA susceptibility breakpoint for dalbavancin.

Conclusion

Vancomycin should be considered as a surrogate for in vitro dalbavancin susceptibility testing.

Development of novel antibacterial drugs to combat multiple resistant organisms

BACKGROUND

Infections due to multidrug-resistant (MDR) bacteria are increasing both in hospitals and in the community and are characterized by high mortality rates. New molecules are in development to face the need of active compounds toward resistant gram-positive and gram-negative pathogens. In particular, the Infectious Diseases Society of America (IDSA) has supported the initiative to develop ten new antibacterials within 2020. Principal targets are the so-called ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa, and Enterobacteriaceae).

PURPOSE

To review the characteristics and the status of development of new antimicrobials including new cephalosporins, carbapenems, beta-lactamase inhibitors, aminoglycosides, quinolones, oxazolidones, glycopeptides, and tetracyclines.

CONCLUSIONS

While numerous new compounds target resistant gram-positive pathogens and have been approved for clinical use, very few new molecules are active against MDR gram-negative pathogens, especially carbapenemase producers. New glycopeptides and oxazolidinones are highly efficient against methicillin-resistant S. aureus (MRSA), and new cephalosporins and carbapenems also display activity toward MDR gram-positive bacteria. Although new cephalosporins and carbapenems have acquired activity against MRSA, they offer few advantages against difficult-to-treat gram-negatives. Among agents that are potentially active against MDR gram-negatives are ceftozolane/tazobactam, new carbapenems, the combination of avibactam with ceftazidime, and plazomicin. Since a relevant number of promising antibiotics is currently in development, regulatory approvals over the next 5 years are crucial to face the growing threat of multidrug resistance.

β-Lactam combinations with daptomycin provide synergy against vancomycin-resistant Enterococcus faecalis and Enterococcus faecium

OBJECTIVES

Enterococcus faecalis (Efc) and Enterococcus faecium (Efm) are frequently resistant to vancomycin and β-lactams (BLs). In vitro data suggest synergy between several BLs and glycopeptides or lipopeptides against resistant pathogens. Our objective was to conduct combination MIC and time-kill experiments to evaluate BL synergy with daptomycin against enterococci.

METHODS

Fifteen Efc and 20 Efm strains were evaluated for daptomycin enhancement via combination MICs. Daptomycin MICs were obtained by microdilution in the absence and presence of ceftaroline, ertapenem, cefepime, ceftriaxone, cefotaxime, cefazolin and ampicillin. Two Efc strains (R6981 and R7808) and one isogenic daptomycin-susceptible/daptomycin-non-susceptible Efm pair (8019/5938) were evaluated in time-kill experiments. Daptomycin at 0.5 × MIC was used in combination with BL at biological free concentration. Strain 5938 was evaluated for enhancement of daptomycin binding in fluorescently labelled daptomycin (BoDipy) experiments.

RESULTS

Ceftaroline reduced daptomycin MIC values the most against all strains. In time-kill experiments, ceftaroline, ertapenem, cefepime, ceftriaxone and ampicillin demonstrated synergy with daptomycin against all strains, cefazolin demonstrated none and cefotaxime demonstrated synergy against only R7808. Bacterial reduction at 24 h was greater for daptomycin + ceftaroline, ertapenem, cefepime, ceftriaxone or ampicillin for all strains compared with any single agent or daptomycin + cefazolin or cefotaxime (P < 0.001). In BoDipy daptomycin experiments, ceftaroline enhanced daptomycin binding most compared with all other agents (P < 0.001).

CONCLUSIONS

The data support the potential use of daptomycin/BL combination therapy in infections caused by VRE. Combination regimens, other than those involving cefazolin and cefotaxime, provide better kill compared with daptomycin alone. Further clinical research involving daptomycin combinations is warranted.

Extended-duration dosing and distribution of dalbavancin into bone and articular tissue

Dalbavancin is an intravenous lipoglycopeptide with activity against Gram-positive pathogens and an MIC90 for Staphylococcus aureus of 0.06 μg/ml. With a terminal half-life of >14 days, dosing regimens with infrequent parenteral administration become available to treat infectious diseases such as osteomyelitis and endocarditis that otherwise require daily dosing for many weeks. In order to support a rationale for these novel regimens, the pharmacokinetics over an extended dosing interval and the distribution of dalbavancin into bone and articular tissue were studied in two phase I trials and pharmacokinetic modeling was performed. Intravenous administration of 1,000 mg of dalbavancin on day 1 followed by 500 mg weekly for seven additional weeks was well tolerated and did not demonstrate evidence of drug accumulation. In a separate study, dalbavancin concentrations in cortical bone 12 h after infusion of a single 1,000-mg intravenous infusion were 6.3 μg/g and 2 weeks later were 4.1 μg/g. A two-dose, once-weekly regimen that would provide tissue exposure over the dalbavancin MIC for Staphylococcus aureus for 8 weeks, maximizing the initial exposure to treatment while minimizing the frequency of intravenous therapy, is proposed.

Low vancomycin MICs and fecal densities reduce the sensitivity of screening methods for vancomycin resistance in Enterococci

Active surveillance is part of a multifaceted approach used to prevent the spread of vancomycin-resistant enterococci (VRE). The impact of fecal density, the vancomycin MIC of the isolate, and the vancomycin concentration in liquid medium on test performance are uncertain. Using fecal specimens spiked with a collection of 18 VRE (predominantly vanB) with a wide vancomycin MIC range, we compared the performances of commercial chromogenic agars (CHROMagar VRE, chromID VRE, Brilliance VRE, and VRE Select) and 1 liquid medium (Enterococcosel enrichment broth) for VRE detection. The specificity of solid media was excellent; however, the sensitivity at 48 h varied from 78 to 94%. Screening using liquid medium was less sensitive than screening with solid media, particularly as the vancomycin content increased. Sensitivity declined (i) as the fecal VRE density decreased, (ii) when the media were assessed at 24 h (versus 48 h), and (iii) for isolates with a low vancomycin MIC (sensitivity, 25 to 75% versus 100% for isolates with vancomycin MIC of <16 mg/liter versus >32 mg/liter on solid medium using 10(6) CFU/ml of feces). Depending on local epidemiology and in particular VRE vancomycin MICs, the sensitivity of culture-based methods for VRE screening of stool or rectal specimens may be suboptimal, potentially facilitating secondary transmission.

Determination of vancomycin pharmacokinetics in neonates to develop practical initial dosing recommendations

Variability in neonatal vancomycin pharmacokinetics and the lack of consensus for optimal trough concentrations in neonatal intensive care units pose challenges to dosing vancomycin in neonates. Our objective was to determine vancomycin pharmacokinetics in neonates and evaluate dosing regimens to identify whether practical initial recommendations that targeted trough concentrations most commonly used in neonatal intensive care units could be determined. Fifty neonates who received vancomycin with at least one set of steady-state levels were evaluated retrospectively. Mean pharmacokinetic values were determined using first-order pharmacokinetic equations, and Monte Carlo simulation was used to evaluate initial dosing recommendations for target trough concentrations of 15 to 20 mg/liter, 5 to 20 mg/liter, and ≤20 mg/liter. Monte Carlo simulation revealed that dosing by mg/kg of body weight was optimal where intermittent dosing of 9 to 12 mg/kg intravenously (i.v.) every 8 h (q8h) had the highest probability of attaining a target trough concentration of 15 to 20 mg/liter. However, continuous infusion with a loading dose of 10 mg/kg followed by 25 to 30 mg/kg per day infused over 24 h had the best overall probability of target attainment. Initial intermittent dosing of 9 to 15 mg/kg i.v. q12h was optimal for target trough concentrations of 5 to 20 mg/liter and ≤20 mg/liter. In conclusion, we determined that the practical initial vancomycin dose of 10 mg/kg vancomycin i.v. q12h was optimal for vancomycin trough concentrations of either 5 to 20 mg/liter or ≤20 mg/liter and that the same initial dose q8h was optimal for target trough concentrations of 15 to 20 mg/liter. However, due to large interpatient vancomycin pharmacokinetic variability in neonates, monitoring of serum concentrations is recommended when trough concentrations between 15 and 20 mg/liter or 5 and 20 mg/liter are desired.

New antibiotics for bad bugs: where are we?

Bacterial resistance to antibiotics is growing up day by day in both community and hospital setting, with a significant impact on the mortality and morbidity rates and the financial burden that is associated. In the last two decades multi drug resistant microorganisms (both hospital- and community-acquired) challenged the scientific groups into developing new antimicrobial compounds that can provide safety in use according to the new regulation, good efficacy patterns, and low resistance profile. In this review we made an evaluation of present data regarding the new classes and the new molecules from already existing classes of antibiotics and the ongoing trends in antimicrobial development. Infectious Diseases Society of America (IDSA) supported a proGram, called “the ′10 × ´20′ initiative”, to develop ten new systemic antibacterial drugs within 2020. The microorganisms mainly involved in the resistance process, so called the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa, and enterobacteriaceae) were the main targets. In the era of antimicrobial resistance the new antimicrobial agents like fifth generation cephalosporins, carbapenems, monobactams, β-lactamases inhibitors, aminoglycosides, quinolones, oxazolidones, glycopeptides, and tetracyclines active against Gram-positive pathogens, like vancomycin-resistant S. aureus (VRSA) and MRSA, penicillin-resistant streptococci, and vancomycin resistant Enterococcus (VRE) but also against highly resistant Gram-negative organisms are more than welcome. Of these compounds some are already approved by official agencies, some are still in study, but the need of new antibiotics still does not cover the increasing prevalence of antibiotic-resistant bacterial infections. Therefore the management of antimicrobial resistance should also include fostering coordinated actions by all stakeholders, creating policy guidance, support for surveillance and technical assistance.