Engineered peptide PLG0206 overcomes limitations of a challenging antimicrobial drug class.

The absence of novel antibiotics for drug-resistant and biofilm-associated infections is a global public health crisis. Antimicrobial peptides explored to address this need have encountered significant development challenges associated with size, toxicity, safety profile, and pharmacokinetics. We designed PLG0206, an engineered antimicrobial peptide, to address these limitations. PLG0206 has broad-spectrum activity against >1,200 multidrug-resistant (MDR) ESKAPEE clinical isolates, is rapidly bactericidal, and displays potent anti-biofilm activity against diverse MDR pathogens. PLG0206 displays activity in diverse animal infection models following both systemic (urinary tract infection) and local (prosthetic joint infection) administration. These findings support continuing clinical development of PLG0206 and validate use of rational design for peptide therapeutics to overcome limitations associated with difficult-to-drug pharmaceutical targets.

A Phase 1 Study To Evaluate Safety and Pharmacokinetics following Administration of Single and Multiple Doses of the Antistaphylococcal Lysin LSVT-1701 in Healthy Adult Subjects.

Thirty-two healthy male subjects (8 per cohort) were randomized 6:2 to active:placebo. LSVT-1701, an antistaphylococcal lysin, was administered intravenously as a 6-mg/kg single dose and as 1.5, 3, and 4.5 mg/kg twice daily for 4 days. LSVT-1701 exposure increased in a greater than dose proportional manner and did not accumulate. Treatment-emergent adverse events (TEAEs) were predominantly of mild intensity. The most common TEAEs were chills, pyrexia, headache, infusion site events, cough, rhinorrhea, and increases in C-reactive protein. (This study has been registered at ClinicalTrials.gov under identifier NCT03446053.).

Anti-staphylococcal lysin, LSVT-1701, activity: In vitro susceptibility of Staphylococcus aureus and coagulase-negative staphylococci (CoNS) clinical isolates from around the world collected from 2002 to 2019.

LSVT-1701 (previously known as SAL200), is a novel, recombinantly-produced, bacteriophage-encoded lysin that specifically targets staphylococci via cell wall enzymatic hydrolysis. In vitro activities of LSVT-1701 and comparators were tested against 415 Staphylococcus aureus and coagulase-negative staphylococci (CoNS) clinical isolates expressing various resistance phenotypes. The isolates were collected worldwide from 2002 to 2019 and tested for in vitro susceptibility using broth microdilution methodology performed according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. Minimum inhibitory concentration (MIC) interpretations were based on CLSI and EUCAST criteria. MIC90 for all S. aureus, methicillin-susceptible S. aureus, methicillin-resistant S. aureus, and CoNS, were 2, 2, 2 and 2 µg/ml, respectively. LSVT-1701's activity was not adversely affected by resistance to antimicrobial comparators against this worldwide collection of S. aureus and CoNS clinical isolates. The results of this study support further clinical development of LSVT-1701 to treat staphylococcal infections, including those caused by multidrug resistance isolates.

Efficacy of Antistaphylococcal Lysin LSVT-1701 in Combination with Daptomycin in Experimental Left-Sided Infective Endocarditis Due to Methicillin-Resistant Staphylococcus aureus.

We utilized the rabbit model of aortic valve infective endocarditis to examine the combined efficacy of the lysin LSVT-1701 plus daptomycin. The combination of LSVT-1701 plus daptomycin was highly effective at reducing methicillin-resistant Staphylococcus aureus (MRSA) counts in target tissue. When given for four daily doses, both lysin dose regimens in combination with daptomycin sterilized all target tissues. These findings suggest that LSVT-1701 warrants further clinical evaluation as an adjunctive therapy for the treatment of invasive MRSA infections.

In vitro activity of iclaprim and comparator agents against Listeria monocytogenes clinical isolates from 2012 to 2018.

OBJECTIVES: This study examined the in vitro activity of iclaprim and comparators against 40 Listeria monocytogenes clinical isolates mostly (95%) from patients with bloodstream infection (BSI) from the USA, Australia/New Zealand, Latin America and Europe collected between 2012-2018. METHODS: Antimicrobial susceptibility testing was performed according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Minimum inhibitory concentration (MIC) interpretations were based on CLSI criteria. RESULTS: The iclaprim MIC90 value for all L. monocytogenes was 0.015 µg/mL. The MIC50/90 values for iclaprim were 4-fold lower than trimethoprim, the only FDA-approved dihydrofolate reductase inhibitor, against all L. monocytogenes. CONCLUSION: Iclaprim demonstrated lower MIC values than trimethoprim against a collection (2012-2018) of L. monocytogenes clinical isolates mostly from patients with BSI from the USA, Australia/New Zealand, Latin America and Europe.

The activity of the diaminopyrimidine dihydrofolate reducatase inhibitor, iclaprim, against Toxoplasma gondii in an in vitro model: a pilot study.

The objective of this pilot study was to examine the activity of iclaprim, a diaminopyrimidine dihydrofolate reducatase inhibitor, in an in vitro infection model of infection with Toxoplasma gondii. Toxoplasma growth was assessed by enzyme linked immunoassay (ELISA) performed directly on the fixed cultures using a peroxidase labeled monoclonal antibody directed against the SAG-l surface protein of T. gondii. For each well, the results were expressed as optical density (OD) values. Iclaprim inhibited T. gondii growth at concentrations between 0.1 and 10 mg/L; the IC50 was estimated at 0.26 mg/L (95% confidence interval 0.22-0.33). Iclaprim was about 10 times more active than trimethoprim, which had an IC50 of 2.3 mg/L. Iclaprim demonstrated synergistic effects at concentrations of 0.02, 0.05 and 0.1 mg/L when combined with subinhibitory concentrations of sulfamethoxazole (0.1 or 0.02 mg/L). These results show that iclaprim is a potent inhibitor of T. gondii growth in vitro. In addition, iclaprim exhibited synergy in vitro when tested in the presence of sulfamethoxazole. Iclaprim should be further investigated as an agent for the treatment or prophylaxis of toxoplasmosis.

Effect of Vancomycin-Associated Acute Kidney Injury on Incidence of 30-Day Readmissions among Hospitalized Veterans Affairs Patients with Skin and Skin Structure Infections.

Among hospitalized adults who received vancomycin for their skin and skin structure infection (SSSI), patients who experienced acute kidney injury (AKI) had considerably higher 30-day readmission rates. Nearly half of the observed 30-day readmissions were due to non-SSSI-related reasons, which is consistent with the persistent organ dysfunction observed among patients with AKI.

A pooled analysis of patients with wound infections in the Phase 3 REVIVE trials: randomized, double-blind studies to evaluate the safety and efficacy of iclaprim versus vancomycin for treatment of acute bacterial skin and skin structure infections.

Introduction. Iclaprim is a diaminopyrimidine antibiotic for the treatment of acute bacterial skin and skin structure infections (ABSSSI) due to Gram-positive pathogens.Aim. This analysis evaluates patients with wound infections from two Phase 3 trials of ABSSSI.Methodology. Six-hundred-two patients with wound infections from two Phase 3, double-blinded, randomized, multicenter, active controlled trials (REVIVE-1/-2) were evaluated in a post hoc analysis of iclaprim 80 mg compared with vancomycin 15 mg kg-1 administered intravenously every 12 h for 5-14 days. The primary endpoint was to determine whether iclaprim was non-inferior (10 % margin) to vancomycin in achieving a ≥20 % reduction from baseline in lesion size 48-72 h after starting study drug (early clinical response [ECR]). Safety was assessed.Results. In REVIVE-1, ECR was 83.5 % with iclaprim versus 79.7 % with vancomycin (treatment difference 3.77%, 95 % CI -4.50%, 12.04%). In REVIVE-2, ECR was 82.7 % with iclaprim versus 76.3 % with vancomycin (treatment difference 6.38%, 95 % CI -3.35%, 16.12%). In the pooled dataset, iclaprim had similar ECR rates compared with vancomycin among wound infection patients (83.2 % vs 78.2 %) with a treatment difference of 5.01 % (95 % CI -1.29%, 11.32%). The safety profile was similar in iclaprim- and vancomycin-treated patients, except for a higher incidence of diarrhea with vancomycin (n=17) compared with iclaprim (n=6) and fatigue with iclaprim (n=17) compared with vancomycin (n=8).Conclusion. Based on early clinical response, iclaprim achieved non-inferiority to vancomycin with a similar safety profile in patients with wound infections suspected or confirmed as caused by Gram-positive pathogens. Iclaprim may be a valuable treatment option for wound infections.

Worldwide surveillance of Iclaprim activity: In Vitro susceptibility of gram-positive pathogens collected from patients with skin and skin structure infections from 2013 to 2017.

Iclaprim is a novel diaminopyrimidine, which inhibits bacterial dihydrofolate reductase, and it is active against Gram-positive pathogens including emerging drug-resistant pathogens. In vitro activity of iclaprim and comparators against 1365 Gram-positive clinical isolates from patients with skin and skin structure infections (SSSI) from the United States, Asia Pacific, Latin America, Europe, Africa or Middle East collected between 2013 and 2017 were tested. Susceptibility testing was performed according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. Minimum inhibitory concentration (MIC) interpretations were based on CLSI criteria. MIC90 for all S.aureus, methicillin-susceptible S. aureus, methicillin-resistant S. aureus, Streptococcus pyogenes, S. agalactiae, S. anginosus, S. constellatus, S. dysgalactiae and S. intermedius were 0.12, 0.12, 0.5, 0.03, 0.5, ≤0.004, ≤0.004, 0.12, and 0.008 µg/ml, respectively. The MIC for iclaprim was 8 to 32-fold lower than trimethoprim, the only FDA approved dihydrofolate reductase inhibitor, against all Gram-positive isolates including resistant phenotypes. Iclaprim demonstrated lower MICs than trimethoprim against a collection (2013-2017) of Gram-positive clinical isolates from patients with SSSI from the United States, Asia Pacific, Latin America, and Europe.

A Multicenter Evaluation of Vancomycin-Associated Acute Kidney Injury in Hospitalized Patients with Acute Bacterial Skin and Skin Structure Infections.

BACKGROUND: We sought to determine the real-world incidence of and risk factors for vancomycin-associated acute kidney injury (V-AKI) in hospitalized adults with acute bacterial skin and skin structure infections (ABSSSI). METHODS: Retrospective, observational, cohort study at ten U.S. medical centers between 2015 and 2019. Hospitalized patients treated with vancomycin (≥ 72 h) for ABSSSI and ≥ one baseline AKI risk factor were eligible. Patients with end-stage kidney disease, on renal replacement therapy or AKI at baseline, were excluded. The primary outcome was V-AKI by the vancomycin guidelines criteria. RESULTS: In total, 415 patients were included. V-AKI occurred in 39 (9.4%) patients. Independent risk factors for V-AKI were: chronic alcohol abuse (aOR 4.710, 95% CI 1.929-11.499), no medical insurance (aOR 3.451, 95% CI 1.310-9.090), ICU residence (aOR 4.398, 95% CI 1.676-11.541), Gram-negative coverage (aOR 2.926, 95% CI 1.158-7.392) and vancomycin duration (aOR 1.143, 95% CI 1.037-1.260). Based on infection severity and comorbidities, 34.7% of patients were candidates for oral antibiotics at baseline and 39.3% had non-purulent cellulitis which could have been more appropriately treated with a beta-lactam. Patients with V-AKI had significantly longer hospital lengths of stay (9 vs. 6 days, p = 0.001), higher 30-day readmission rates (30.8 vs. 9.0%, p < 0.001) and increased all-cause 30-day mortality (5.1 vs. 0.3%, p = 0.024) CONCLUSIONS: V-AKI occurred in approximately one in ten ABSSSI patients and may be largely prevented by preferential use of oral antibiotics whenever possible, using beta-lactams for non-purulent cellulitis and limiting durations of vancomycin therapy.

In Vitro Activities of ß-Lactam-ß-Lactamase Inhibitor Antimicrobial Agents against Cystic Fibrosis Respiratory Pathogens.

We tested the in vitro activities of ceftazidime-avibactam, ceftolozane-tazobactam, meropenem-vaborbactam, piperacillin-tazobactam, and 11 other antimicrobial agents against 420 Burkholderia, Achromobacter, Stenotrophomonas, and Pandoraea strains, 89% of which were cultured from respiratory specimens from persons with cystic fibrosis. Among the ß-lactam-ß-lactamase inhibitor agents, meropenem-vaborbactam had the greatest activity against Burkholderia and Achromobacter, including multidrug-resistant and extensively-drug-resistant strains. None of the newer ß-lactam-ß-lactamase combination drugs showed increased activity compared to that of the older agents against Stenotrophomonas maltophilia or Pandoraea spp.

The incidence and patient outcomes of ABSSSI by iclaprim MIC values in the phase 3 REVIVE trials for treatment of acute bacterial skin and skin structure infections.

The incidence and patient outcomes of Staphylococcus aureus isolates by iclaprim MIC was determined among patients from two phase 3 studies for the treatment of acute bacterial skin and skin structure infections (ABSSSI), REVIVE-1 and -2. Iclaprim MIC90 values were 0.12 µg ml-1 for S. aureus (0.12 µg ml-1 against methicillin-sensitive and 0.25 µg ml-1 against methicillin-resistant S. aureus). The incidence of culture confirmed S. aureus isolates among patients with ABSSSI with an iclaprim MIC > 8 µg ml-1 was 2.0  % (16/790). The clinical outcomes varied by MICs for early clinical response (63-100  %), end of therapy response (81-100  %) and the test of cure response (75-100  %). For microbiological outcomes of these infections, the end of therapy response was 80-100  % and the test of cure response was 88-100  %.

A Pooled Analysis of the Safety and Efficacy of Iclaprim Versus Vancomycin for the Treatment of Acute Bacterial Skin and Skin Structure Infections in Patients With Intravenous Drug Use: Phase 3 REVIVE Studies.

PURPOSE: This analysis evaluates the efficacy and safety of iclaprim versus vancomycin for the treatment of acute bacterial skin and skin structure infections (ABSSSIs) in patients who were intravenous drug users (IVDUs). METHODS: A total of 621 patients who were IVDUs from 2 parallel Phase III, double-blind, randomized (1:1), active-controlled, multinational, multicenter trials (REVIVE-1 and REVIVE-2) were analyzed separately and pooled. This post hoc analysis summarizes the efficacy and safety profile of iclaprim 80 mg fixed dose compared with vancomycin 15 mg/kg administered intravenously during 2 h every 12 h for 5-14 days among this population. The primary end point of these studies was to determine whether iclaprim was noninferior (10% margin) to vancomycin in achieving a ≥20% reduction in lesion size at 48-72 h after initiation of treatment with the study drug (early clinical response) in the intent-to-treat population. The safety profile was assessed based on adverse events and laboratory parameters. FINDINGS: Iclaprim had higher early clinical response rates (85.8%; 95% CI, 81.5%-89.4%) compared with vancomycin (79.8%; 95% CI, 74.8%-84.2%) among patients with ABSSSIs who were IVDUs, with a treatment difference of +6.00% (95% CI, 0.06-12.0). The safety profile was similar in the iclaprim and vancomycin arms, with 3.7% and 5.0%, respectively, of patients discontinuing study therapy because of adverse events and 1.9% and 3.4%, respectively, of patients developing serious adverse events. IMPLICATIONS: Iclaprim had a higher early clinical response rate and favorable safety profile compared with vancomycin for the treatment of ABSSSIs in patients who were IVDUs. Iclaprim may be a valuable treatment option for ABSSSIs in this patient population.

The Basics and the Advancements in Diagnosis of Bacterial Lower Respiratory Tract Infections.

Lower respiratory tract infections (LRTIs) are the leading infectious cause of death and the sixth-leading cause of death overall worldwide. Streptococcus pneumoniae, with more than 90 serotypes, remains the most common identified cause of community-acquired acute bacterial pneumonia. Antibiotics treat LRTIs with a bacterial etiology. With the potential for antibiotic-resistant bacteria, defining the etiology of the LRTI is imperative for appropriate patient treatment. C-reactive protein and procalcitonin are point-of-care tests that may differentiate bacterial versus viral etiologies of LRTIs. Major advancements are currently advancing the ability to make rapid diagnoses and identification of the bacterial etiology of LRTIs, which will continue to support antimicrobial stewardship, and is the focus of this review.

The effects of iclaprim on exotoxin production in methicillin-resistant and vancomycin-intermediate Staphylococcus aureus.

PURPOSE: Extracellular protein toxins contribute to the pathogenesis of Staphylococcus aureus infections. The present study compared the effects of iclaprim and trimethoprim - two folic acid synthesis inhibitors - with nafcillin and vancomycin on production of Panton-Valentine leukocidin (PVL), alpha haemolysin (AH) and toxic-shock syndrome toxin I (TSST-1) in methicillin-resistant and vancomycin-intermediate S. aureus (MRSA and VISA, respectively). METHODOLOGY: Northern blotting and RT-PCR were used to assess gene transcription; toxin-specific bioassays were used to measure protein toxin production. RESULTS: As shown previously, sub-inhibitory concentrations (sub-MIC) of nafcillin increased and prolonged MRSA toxin gene transcription and enhanced PVL, TSST-1 and AH production. Sub-inhibitory doses of iclaprim and trimethoprim delayed maximal AH gene (hla) transcription and suppressed AH production; both drugs delayed, but neither reduced, maximal TSST-1 production. Trimethoprim significantly increased lukF-PV expression and PVL production compared to both untreated and iclaprim-treated cultures. Higher concentrations of iclaprim and trimethoprim markedly suppressed MRSA growth, mRNA synthesis and toxin production. In VISA, iclaprim, vancomycin and nafcillin variably increased tst and hla expression, but only nafcillin increased toxin production. Despite its ability to increase hla expression, iclaprim was the most potent inhibitor of AH production. CONCLUSIONS: We conclude that, due to its ability to suppress toxin production, iclaprim should be effective against severe staphylococcal infections caused by toxin-producing MRSA and VISA strains, especially given its ability to concentrate at sites of infection such as skin and skin structures and the lung.

In Vitro Activity of Iclaprim against Isolates in Two Phase 3 Clinical Trials (REVIVE-1 and -2) for Acute Bacterial Skin and Skin Structure Infections.

Iclaprim, a selective bacterial dihydrofolate reductase inhibitor, and other antibiotics were tested against Gram-positive isolates from two phase 3 studies of acute bacterial skin and skin structure infections (ABSSSIs) (REVIVE-1 and -2). Seven hundred ninety baseline isolates, including Staphylococcus aureus, ß-hemolytic streptococci, and Streptococcus anginosus group, underwent antibacterial susceptibility testing. Iclaprim had an MIC90 of 0.12 µg/ml for S. aureus (0.12 µg/ml for methicillin susceptible, 0.25 µg/ml for methicillin resistant), 0.25 µg/ml for ß-hemolytic streptococci, and 0.008 µg/ml for S. anginosus group. Iclaprim demonstrated potent activity against these Gram-positive ABSSSI isolates.

In vitro activity of dihydrofolate reductase inhibitors and other antibiotics against Gram-positive pathogens collected globally between 2004 and 2016.

OBJECTIVES: The objective of this study was to determine the in vitro activity of iclaprim and comparator agents against 7618 Gram-positive clinical isolates collected in the periods 2004-2006, 2012-2014 and 2015-2016. METHODS: Antimicrobial susceptibility testing was performed by the broth microdilution method and the minimum inhibitory concentrations (MICs) were interpreted according to Clinical and Laboratory Standards Institute (CLSI) guidelines. RESULTS: Iclaprim MIC50/MIC90 values were 0.06/0.12µg/mL for Staphylococcus aureus, including methicillin-susceptible and methicillin-resistant strains, and 0.015/0.03, 0.12/0.5 and 0.03/0.06µg/mL, respectively, for Streptococcus pyogenes, Streptococcus agalactiae and Streptococcus dysgalactiae over 8 years within the period from 2004 to 2016. Iclaprim was 8-32-fold more potent than trimethoprim. Against S. aureus, including methicillin-resistant strains, iclaprim was more active than standard-of-care intravenous antibiotics used to treat Gram-positive skin infections. Iclaprim was up to 16-fold more potent than vancomycin and linezolid and was 4-8-fold more potent than daptomycin. CONCLUSIONS: Iclaprim demonstrated potent and consistent activity among Gram-positive clinical isolates collected globally between 2004 and 2016.

Evaluation of in vitro activity of iclaprim in combination with other antimicrobials against pulmonary pathogens: a pilot study.

In this pilot study, the in vitro antimicrobial activity of iclaprim, a diaminopyrimidine, tested in combination with other antimicrobials against recent and common Gram-positive and Gram-negative respiratory pathogens, was examined by the checkerboard method. The range of minimal inhibitory concentrations (MICs) for iclaprim against all bacteria tested in the study was 0.03 to >128 µg ml-1. Iclaprim exhibited synergy with sulfamethoxazole against 11 of the 16 bacterial strains tested, with mean fractional inhibitory concentration index (FICI) values of 0.2-0.5. Synergy with sulfamethoxazole was demonstrated against all Gram-positive bacteria and selected Gram-negative bacteria. Neither synergy nor antagonism was observed for combinations of iclaprim with ampicillin, meropenem, tetracycline, levofloxacin, aztreonam, piperacillin/tazobactam, colistin, cefepime or gentamicin against any of the bacterial strains tested. The significant reduction in the MIC values observed with the combination of iclaprim and sulfamethoxazole demonstrates that this regimen could be effective against common Gram-positive and selected Gram-negative respiratory bacteria.

Surveillance of iclaprim activity: in vitro susceptibility of Gram-positive skin infection pathogens collected from 2015 to 2016 from North America and Europe.

Iclaprim is a diaminopyrimidine, which inhibits bacterial dihydrofolate reductase, and surveillance data prior to 2006 suggested that iclaprim was active against Gram-positive pathogens including emerging drug-resistant pathogens. In an era of increasing antimicrobial resistance, we undertook testing iclaprim and comparators against 931 Gram-positive clinical isolates from the United States and Europe collected between 2015 and 2016. Susceptibility testing was performed according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. Minimum inhibitory concentration (MIC) interpretations were based on CLSI and European Committee on Antimicrobial Susceptibility Testing criteria. MIC50/MIC90 was 0.03/0.12 for all Staphylococcus aureus, 0.06/0.06 for methicillin-susceptible S. aureus, 0.03/0.12 for methicillin-resistant S. aureus, 0.12/0.5 for Streptococcus agalactiae, ≤0.015/≤0.015 for Streptococcus anginosus, 0.03/0.06 for Streptococcus dysgalactiae, and ≤0.015 /0.03 µg/mL for Streptococcus pyogenes. Iclaprim was active against a contemporary collection (2015-2016) of Gram-positive bacteria isolated from the skin or soft tissue from patients with SSSI from the United States and Europe.