In vitro activity of cefiderocol against European Enterobacterales, including isolates resistant to meropenem and recentβ-lactam/β-lactamase inhibitor combinations

Carbapenem-resistant Enterobacterales represent a major health threat and have few approved therapeutic options. Enterobacterales isolates were collected from hospitalized inpatients from 49 sites in six European countries (1 January-31 December 2020) and underwent susceptibility testing to cefiderocol and β-lactam/β-lactamase inhibitor combinations. Meropenem-resistant (MIC >8 mg/L) and cefiderocol-susceptible isolates were analyzed by PCR, and cefiderocol-‍resistant isolates by whole-genome sequencing, to identify resistance mechanisms. Overall, 1,909 isolates (including 970 Klebsiella spp., 382 Escherichia coli, and 244 Enterobacter spp.) were collected, commonly from bloodstream infections (43.6%). Cefiderocol susceptibility was higher than approved β-lactam/β-lactamase inhibitor combinations and largely comparable to cefepime-taniborbactam and aztreonam-avibactam against all Enterobacterales (98.1% vs 78.1%-‍97.4% and 98.7%-99.1%, respectively) and Enterobacterales resistant to meropenem (n = 148, including 125 Klebsiella spp.; 87.8% vs 0%-71.6% and 93.2%-98.6%, respectively), β-lactam/β-lactamase inhibitor combinations (66.7%-‍92.1% vs 0%-‍88.1% and 66.7%-97.9%, respectively), and to both meropenem and β-‌lactam/β-lactamase inhibitor combinations (61.9%-65.9% vs 0%-‍20.5% and 76.2%-97.7%, respectively). Susceptibilities to approved and developmental β-lactam/β-lactamase inhibitor combinations against cefiderocol-resistant Enterobacterales (n = 37) were 10.8%-‍56.8% and 78.4%-94.6%, respectively. Most meropenem-resistant Enterobacterales harbored Klebsiella pneumoniae carbapenemase (110/148) genes, although metallo-β-lactamase (35/148) and oxacillinase (OXA) carbapenemase (6/148) genes were less common; cefiderocol susceptibility was retained in β-lactamase producers, other than NDM, AmpC, and non-carbapenemase OXA producers. Most cefiderocol-resistant Enterobacterales had multiple resistance mechanisms, including ≥1 iron uptake-related mutation (37/37), carbapenemase gene (33/37), and ftsI mutation (24/37). The susceptibility to cefiderocol was higher than approved β-lac‌tam/β-lactamase inhibitor combinations against European Enterobacterales, including meropenem- and β-lactam/β-lactamase inhibitor combination-resistant isolates.

IMPORTANCE

This study collected a notably large number of Enterobacterales isolates from Europe, including meropenem- and β-lactam/β-lactamase inhibitor combination-resistant isolates against which the in vitro activities of cefiderocol and developmental β-lactam/β-lactamase inhibitor combinations were directly compared for the first time. The MIC breakpoint for high-dose meropenem was used to define meropenem resistance, so isolates that would remain meropenem resistant with doses clinically available to patients were included in the data. Susceptibility to cefiderocol, as a single active compound, was high against Enterobacterales and was higher than or comparable to available β-lactam/β-lactamase inhibitor combinations. These results provide insights into the treatment options for infections due to Enterobacterales with resistant phenotypes. Early susceptibility testing of cefiderocol in parallel with β-lactam/β-lactamase inhibitor combinations will allow patients to receive the most appropriate treatment option(s) available in a timely manner. This is particularly important when options are more limited, such as against metallo-β-lactamase-producing Enterobacterales.

Evaluation of the activity of cefepime/enmetazobactam against Enterobacterales bacteria collected in Europe from 2019 to 2021, including third-generation cephalosporin-resistant isolates

OBJECTIVES

This study was performed to investigate the activity of the novel ß-lactam/ß-lactamase inhibitor combination cefepime/enmetazobactam, against recently circulating Enterobacterales isolates from Europe from 2019 to 2021.

METHODS

A total of 2627 isolates were collected, and antimicrobial susceptibility was determined according to the European Committee on Antimicrobial Susceptibility Testing guidelines. Isolates with phenotypic resistance to ceftriaxone and ceftazidime (but susceptible to meropenem) and isolates nonsusceptible to meropenem were screened for the presence of ß-lactamases.

RESULTS

Overall, susceptibility to third-generation cephalosporins was 77%, and 97.3% were susceptible to meropenem. Cefepime/enmetazobactam susceptibility was 97.9% (72% of these isolates were Klebsiella pneumoniae from Italy), compared with 80.0% susceptibility to piperacillin/tazobactam and 99.4% to ceftazidime/avibactam. A total of 320 isolates (12.2%) were resistant to third-generation cephalosporins but susceptible to meropenem, and virtually all (96.3%) carried an extended-spectrum ß-lactamase with or without an AmpC and these were all susceptible to cefepime/enmetazobactam. Most meropenem-nonsusceptible isolates carried a KPC (68%), which were not inhibited by cefepime/enmetazobactam but were inhibited by ceftazidime/avibactam. Additionally, most meropenem-nonsusceptible isolates carrying OXA-48 (9/12 isolates) were susceptible to cefepime/enmetazobactam.

CONCLUSIONS

Cefepime/enmetazobactam was highly active against Enterobacterales isolates, especially those resistant to third-generation cephalosporins. These data suggest that cefepime/enmetazobactam could be used as a carbapenem-sparing agent to replace piperacillin/tazobactam.

In vitro activity of cefiderocol against European Pseudomonas aeruginosa and Acinetobacter spp., including isolates resistant to meropenem and recent β-lactam/β-lactamase inhibitor combinations

Carbapenem-resistant Pseudomonas aeruginosa and Acinetobacter spp. represent major threats and have few approved therapeutic options. Non-‍fermenting Gram-negative isolates were collected from hospitalized inpatients from 49 sites in 6 European countries between 01 January 2020 and 31 December 2020 and underwent susceptibility testing against cefiderocol and β-lactam/β-lactamase inhibitor combinations. Meropenem-resistant (MIC >8 mg/L), cefiderocol-susceptible isolates were analyzed by PCR, and cefiderocol-resistant isolates were analyzed by whole-genome sequencing to identify resistance mechanisms. Overall, 1,451 (950 P. aeruginosa; 501 Acinetobacter spp.) isolates were collected, commonly from the respiratory tract (42.0% and 39.3%, respectively). Cefiderocol susceptibility was higher than ‍β‍-‍l‍a‍c‍t‍a‍m‍/‍β‍-‍l‍a‍c‍t‍a‍mase‍ inhibitor combinations against P. aeruginosa (98.9% vs 83.3%-91.4%), and P. ‍aeruginosa resistant to meropenem (n = 139; 97.8% vs 12.2%-59.7%), β-lactam/β-lactamase inhibitor combinations (93.6%-98.1% vs 10.7%-71.8%), and both meropenem and ceftazidime-avibactam (96.7% vs 5.0%-‍‍45.0%) or ‍ceftolozane-tazobactam (98.4% vs 8.1%-54.8%), respectively. Cefiderocol and sulbactam-durlobactam susceptibilities were high against Acinetobacter spp. (92.4% and 97.0%) and meropenem-resistant Acineto‍bacter ‍spp. (n = 227; 85.0% and 93.8%) but lower against sulbactam-durlobactam- (n ‍= 15; 13.3%) and cefiderocol- (n = 38; 65.8%) resistant isolates, respectively. Among meropenem-resistant P. aeruginosa and Acinetobacter spp., the most common β-‍‍lactamase genes were metallo-β-lactamases [30/139; blaVIM-2 (15/139)] and oxacillinases [215/227; blaOXA-23 (194/227)], respectively. Acquired β-lactamase genes were identified in 1/10 and 32/38 of cefiderocol-resistant P. aeruginosa and Acinetobacter spp., and pirA-like or piuA mutations in 10/10 and 37/38, respectively. Conclusion: cefiderocol susceptibility was high against P. aeruginosa and Acinetobacter spp., including meropenem-resistant isolates and those resistant to recent β-lactam/β-lactamase inhibitor combinations common in first-line treatment of European non-fermenters.

IMPORTANCE

This was the first study in which the in vitro activity of cefiderocol and non-licensed β-lactam/β-lactamase inhibitor combinations were directly compared against Pseudomonas aeruginosa and Acinetobacter spp., including meropenem- and β-lactam/β-lactamase inhibitor combination-resistant isolates. A notably large number of European isolates were collected. Meropenem resistance was defined according to the MIC breakpoint for high-dose meropenem, ensuring that data reflect antibiotic activity against isolates that would remain meropenem resistant in the clinic. Cefiderocol susceptibility was high against non-fermenters, and there was no apparent cross resistance between cefiderocol and β-lactam/β-lactamase inhibitor combinations, with the exception of sulbactam-durlobactam. These results provide insights into therapeutic options for infections due to resistant P. aeruginosa and Acinetobacter spp. and indicate how early susceptibility testing of cefiderocol in parallel with β-lactam/β-lactamase inhibitor combinations will allow clinicians to choose the effective treatment(s) from all available options. This is particularly important as current treatment options against non-fermenters are limited.

Meropenem-ANT3310, a unique β-lactam-β-lactamase inhibitor combination with expanded antibacterial spectrum against Gram-negative pathogens including carbapenem-resistant Acinetobacter baumannii

ANT3310 is a novel broad-spectrum diazabicyclooctane serine β-lactamase inhibitor being developed in combination with meropenem (MEM) for the treatment of serious infections in hospitalized patients where carbapenem-resistant Gram-negative pathogens are expected. In this study, we evaluated the in vitro antibacterial activity of MEM in the presence of ANT3310 at 8 µg/mL against global clinical isolates that included Acinetobacter baumannii (n = 905), carbapenem-resistant Enterobacterales (CRE), carrying either oxacillinase (OXA) (n = 252) or Klebsiella pneumoniae carbapenemase (KPC) (n = 180) carbapenemases, and Pseudomonas aeruginosa (n = 502). MEM was poorly active against A. baumannii, as were MEM-vaborbactam, ceftazidime-avibactam, aztreonam-avibactam, cefepime-taniborbactam, cefepime-zidebactam, and imipenem-relebactam (MIC90 values of ≥32 µg/mL). On the other hand, MEM-ANT3310 displayed an MIC90 value of 4 µg/mL, similar to that observed with sulbactam-durlobactam, a drug developed to specifically treat A. baumannii infections. ANT3310 (8 µg/mL) additionally restored the activity of MEM against OXA- and KPC-producing CREs decreasing MEM MIC90 values from >32 µg/mL to 0.25 and 0.5 µg/mL, respectively. The combination of 8 µg/mL of both MEM and ANT3310 prevented growth of 97.5% of A. baumannii and 100% of OXA- and KPC-positive CREs, with ~90% of P. aeruginosa isolates also displaying MEM MICs ≤8 µg/mL. Furthermore, MEM-ANT3310 was efficacious in both thigh and lung murine infection models with OXA-23 A. baumannii. This study demonstrates the potent in vitro activity of the MEM-ANT3310 combination against both carbapenem-resistant A. baumannii and Enterobacterales clinical isolates, a key differentiator to other β-lactam/β-lactamase combinations.

Antimicrobial susceptibility among respiratory tract pathogens isolated from diseased cattle and pigs from different parts of Europe

AIMS

To survey antibiotic susceptibility of bacteria causing cattle and pig respiratory infections in 10 European countries.

METHODS AND RESULTS

Non-replicate nasopharyngeal/nasal or lung swabs were collected from animals with acute respiratory signs during 2015-2016. Pasteurella multocida, Mannheimia haemolytica, Histophilus somni from cattle (n = 281), and P. multocida, Actinobacillus pleuropneumoniae, Glaesserella parasuis, Bordetella bronchiseptica, and Streptococcus suis from pigs (n = 593) were isolated. MICs were assessed following CLSI standards and interpreted using veterinary breakpoints where available. Histophilus somni isolates were fully antibiotic susceptible. Bovine P. multocida and M. haemolytica were susceptible to all antibiotics, except tetracycline (11.6%-17.6% resistance). Low macrolide and spectinomycin resistance was observed for P. multocida and M. haemolytica (1.3%-8.8%). Similar susceptibility was observed in pigs, where breakpoints are available. Resistance in P. multocida, A. pleuropneumoniae, and S. suis to ceftiofur, enrofloxacin, and florfenicol was absent or <5%. Tetracycline resistance varied from 10.6% to 21.3%, but was 82.4% in S. suis. Overall multidrug-resistance was low. Antibiotic resistance in 2015-2016 remained similar as in 2009-2012.

CONCLUSIONS

Low antibiotic resistance was observed among respiratory tract pathogens, except for tetracycline.

In vitro activity of eravacycline and comparators against Gram-negative and Gram-positive bacterial isolates collected from patients globally between 2017 and 2020

OBJECTIVES

To evaluate eravacycline (ERV) activity against Gram-negative and Gram-positive bacteria collected between 2017 and 2020 from worldwide locations.

METHODS

MIC determinations were performed using Clinical and Laboratory Standards Institute (CLSI) broth microdilution methodology. ERV and tigecycline susceptibility was interpreted using United States Food and Drug Administration (FDA) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints. Comparator susceptibility was interpreted using CLSI and EUCAST breakpoints.

RESULTS

ERV MIC₉₀ was 0.5 μg/mL against 12,436 Enterobacteriaceae isolates, which only increased to 1 μg/mL against multidrug-resistant (MDR) isolates (n=2931 (23.6%). Similar activity was shown against 1,893 Acinetobacter baumannii (MIC₉₀ 1 μg/mL) and 356 Stenotrophomonas maltophilia (MIC₉₀ 2 μg/mL). ERV was more active against Gram-positive bacteria: 415 Streptococcus pneumoniae (MIC₉₀ 0.008 μg/mL), 273 S. anginosus group (MIC₉₀ 0.015 μg/mL), 1,876 Enterococcus faecalis and 1,724 E. faecium (MIC₉₀ 2 μg/mL), 2,158 Staphylococcus aureus and 575 S. saprophyticus (MIC₉₀ 0.12 μg/mL), 1,143 S. epidermidis and 423 S. haemolyticus (MIC₉₀ 0.25 μg/mL). ERV MIC₉₀ against methicillin-resistant staphylococci and vancomycin-resistant enterococci was similar to susceptible strains. However, ERV susceptibility varied between EUCAST or FDA against staphylococci, especially S. epidermidis (91.5% vs 47.2%), and vancomycin-resistant E. faecalis (98.3% vs 76.5%).

CONCLUSIONS

This study reaffirms ERV's consistent broad-spectrum activity that has been evaluated since 2003. ERV remains a key agent for the treatment of bacterial infections, including resistant isolates, but urgent re-assessment of clinical breakpoints is required for staphylococci and enterococci.

Study of an antifungal medicine isavuconazole used in treatment of mold infections in China: A plain language summary

WHAT IS THIS SUMMARY ABOUT?

Molds are types of fungus that can cause sickness and death. Mold infections are increasing in China. Until 2022, medicines that can effectively treat all mold infections were still lacking in China. This summary of a study originally published in the journal Infection and Drug Resistance. The study took place in China and tested a medicine called isavuconazole on mold samples to check if isavuconazole can be used to treat mold infections. Isavuconazole became available in China in January 2022 as a capsule (a hard gel-covered pill filled with a dose of medicine) and in June 2022 as an injection or a shot.

WHAT WERE THE RESULTS?

Isavuconazole stopped the growth of most molds. Other medicines were needed at higher amounts to stop the growth of molds.

WHAT DO THE RESULTS OF THE STUDY MEAN?

Isavuconazole is another option to treat mold infections in China.

1681. Activity of the Novel Engineered Antimicrobial Peptide PLG0206 Against Staphylococci and Enterococci

Background

PLG0206 is an investigational, engineered cationic antimicrobial peptide designed to overcome the shortcomings of other natural AMPs, such as toxicity and limited activity. PLG0206 has recently been shown to be well tolerated and safe when administered i.v. in a Phase 1 study. The initial proposed indication for this peptide is the treatment of periprosthetic joint infections via irrigation due to a broad spectrum of activity and anti-biofilm properties. This study evaluated the activity of PLG0206 and comparator antimicrobials against staphylococci and enterococci, causes of periprosthetic joint infections, from the IHMA repository of isolates collected from various world-wide locations in 2019.

Methods

Isolates tested included Enterococcus faecalis (77), E. faecium (75), methicillin-resistant Staphylococcus aureus (MRSA, 180), methicillin-susceptible S. aureus (MSSA, 121) and 152 coagulase-negative staphylococci (CoNS) comprised of S. epidermidis (113), S. haemolyticus (31), S. hominis (4), S. lugdunensis (1), S. saprophyticus (2) and S. simulans (1). Minimum inhibitory concentrations (MICs) were determined by CLSI broth microdilution in cation-adjusted Mueller Hinton broth (CA-MHB), except for PLG0206 which was tested in RPMI medium due to plate-reading difficulties with CA-MHB. The susceptibility of comparators was determined using the 2022 CLSI breakpoints. MDR was defined as resistance to ≥ 3 antibacterial classes.

Results

When tested in RPMI, 18 E. faecalis, 29 E. faecium, 9 S. aureus and 7 CoNS were unable to grow. Summary MIC and susceptibility data for PLG0206 and comparators just including those isolates able to grow in RPMI are shown in the Table. Identical MIC50 and MIC90 values were obtained for PLG0206 when tested against MDR E. faecium (38), MDR CoNS (63) and MDR MRSA (67). Insufficient numbers of MDR MSSA (7) and MDR E. faecalis (4) were tested to accurately evaluate.

Conclusion

PLG0206 was the most potent antimicrobial overall (based on MIC50 and MIC90) against enterococci and CoNS and compared well with the comparators against MRSA and MSSA. These data support the evaluation of this novel antimicrobial peptide as a treatment option for periprosthetic joint infections, including those caused by MDR strains.

Disclosures

David Huang, MD, PhD, Peptilogics: Employee Jonathan Steckbeck, PhD, Peptilogics: I am CEO of Peptilogics.

1680. Activity of the Novel Engineered Antimicrobial Peptide PLG0206 Against Enterobacterales isolates

Background

PLG0206 is an investigational, engineered cationic antimicrobial peptide designed to overcome the shortcomings of other natural AMPs, such as toxicity and limited activity. PLG0206 has recently been shown to be well tolerated and safe in a phase 1 study. This study evaluated the activity of PLG0206 and comparator antimicrobials against Enterobacterales isolates from the IHMA repository collected from various world-wide locations in 2019.

Methods

Isolates tested included Citrobacter spp. (151), Enterobacter cloacae (152), Escherichia coli (300), Klebsiella pneumoniae (300), Morganella morganii (43), Proteus spp. (152), Providencia spp. (61) and Serratia marcescens (45). Minimum inhibitory concentrations (MICs) were determined by CLSI broth microdilution in cation-adjusted Mueller Hinton broth (CA-MHB), except for PLG0206 which was tested in RPMI medium due to plate-reading difficulties with CA-MHB. The susceptibility of comparators was determined using the 2022 CLSI breakpoints. MDR was defined as resistance to ≥ 3 antibacterial classes.

Results

Summary MIC and susceptibility data against Citrobacter spp., E. coli, E. cloacae, and K. pneumoniae are shown in the Table. PLG0206 retained activity against MDR isolates of Citrobacter spp. (26), E. coli (92), E. cloacae (45), and K. pneumoniae (132) with MIC50/90 values of 1/2, 1/2, 1/16 and 8/16 μg/mL, respectively. PLG0206 was essentially inactive against the Morganellaceae and Yersiniaceae isolates tested with MIC50 and MIC90 values of &gt; 32 μg/mL (data not shown).

Conclusion

PLG0206 was active against isolates from the family Enterobacteriaceae, including MDR strains. The spectrum of activity of PLG0206 ranged from being most active against Citrobacter spp. and least active against K. pneumoniae. These data suggest that the novel antimicrobial peptide PLG0206 could be a potential treatment option against infections caused by Enterobacteriaceae isolates.

Disclosures

David Huang, MD, PhD, Peptilogics: Employee Jonathan Steckbeck, PhD, Peptilogics: I am CEO of Peptilogics.

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.

In vitro Activity of Isavuconazole and Comparators Against Clinical Isolates of Molds from a Multicenter Study in China

Purpose

Methods

Results

Conclusion

1043. Activity of Mecillinam Against Enterobacterales Isolates Collected From Patients With Urinary Tract Infections (UTIs) in the USA During 2019

Background

Mecillinam is a β-lactam antibiotic that exerts its antibacterial activity by binding to penicillin-binding protein 2. In the USA, intravenous (IV) mecillinam is in development for the treatment of complicated UTIs in the hospital setting and as step-down therapy transitioning from IV mecillinam to oral pivmecillinam so that patients can continue treatment at home. To support the clinical development of mecillinam in the USA for the treatment of both complicated and uncomplicated UTI, this observational study investigated the activity of mecillinam against Enterobacterales isolates from patients with UTI in the USA, collected during 2019.

Methods

This study evaluated the activity of mecillinam and other antimicrobial agents against 1075 selected Enterobacterales clinical isolates collected from patients with UTI in the USA during 2019. Antibiotic activity (minimum inhibitory concentration [MIC]) was determined by Clinical & Laboratory Standards Institute (CLSI) agar dilution methodology, and susceptibility was interpreted according to CLSI guidelines.

Results

Among the selected 1075 isolates, producers of extended-spectrum beta-lactamase (ESBL) represented 9.6% of Escherichia coli and 50% of Klebsiella pneumoniae. Ninety-five percent of the isolates tested were susceptible to mecillinam (Table 1). The MIC₅₀ and MIC₉₀ values for mecillinam were 0.25 and 2 µg/mL, respectively. Fosfomycin MIC₅₀ and MIC₉₀ were 1 and 32 µg/mL, respectively (97.6% of isolates were susceptible). Mecillinam showed the lowest MIC₉₀ value of all single antibiotics tested. The highest MIC₉₀ was 128 µg/mL for both nitrofurantoin and cefotaxime. The lowest percentage of resistance was obtained with fosfomycin (1.7%), followed by mecillinam (4%).

Table 1: Summary MIC and susceptibility data for all isolates tested (n=1075)

Conclusion

Overall, mecillinam showed excellent activity and a comparable resistance profile to fosfomycin. Resistance rates to ceftazidime, cefotaxime, ciprofloxacin and trimethoprim/sulfamethoxazole of greater than 20% are concerning due to the frequent use of these antibiotics in clinical practice to treat UTIs. Taken together, these data demonstrate that mecillinam has promising activity, with low resistance observed in Enterobacterales species causing UTIs in the USA. Clinical development of mecillinam in the USA is ongoing.

Disclosures

Stephen Hawser, PhD, Utility Therapeutics (Grant/Research Support) Ian Morrissey, Utility Therapeutics (Grant/Research Support) Anne Santerre Henriksen, MS, Advanz (Consultant)Shionogi BV (Consultant)UTILITY Therapeutics (Consultant)

Results from the Survey of Antibiotic Resistance (SOAR) 2015-17 in Turkey: data based on CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints

OBJECTIVES

To determine antibiotic susceptibility of Streptococcus pneumoniae and Haemophilus influenzae isolates from community-acquired respiratory tract infections (CA-RTIs) collected in 2015-17 from Turkey.

METHODS

MICs were determined by CLSI broth microdilution and susceptibility was assessed using CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints.

RESULTS

A total of 179 S. pneumoniae and 239 H. influenzae isolates were collected. Few (27.9%) pneumococci were penicillin susceptible by CLSI oral or EUCAST low-dose breakpoints, but by EUCAST high-dose or CLSI IV breakpoints 84.4% were susceptible. The most active antibiotics (excluding penicillin IV) by CLSI breakpoints were fluoroquinolones (98.9% of isolates susceptible), ceftriaxone (83.2%), amoxicillin (78.8%) and amoxicillin/clavulanic acid (78.8%). Pneumococcal susceptibility to amoxicillin and amoxicillin/clavulanic acid was lower using EUCAST low-dose breakpoints (49.7%), although susceptibility increased when using EUCAST high-dose (57.0%-58.1%) and PK/PD (78.8%-87.7%) breakpoints. Twenty-three H. influenzae isolates were β-lactamase positive, with 11 characterized as β-lactamase negative and ampicillin resistant following EUCAST criteria and 5 by CLSI criteria. Generally antibiotic susceptibility was high using CLSI breakpoints: ≥92.9% for all antibiotics except ampicillin (87% by CLSI and EUCAST breakpoints) and trimethoprim/sulfamethoxazole (67.4% and 72% by CLSI and EUCAST breakpoints, respectively). Susceptibility using EUCAST breakpoints (where these are published) was similar, except for cefuroxime (oral) with 3.8% of isolates susceptible. PK/PD breakpoints indicated low susceptibility to macrolides (5.9%-10%) and cefaclor (13%). The application of different EUCAST breakpoints for low and higher doses for some of the antibiotics (amoxicillin, amoxicillin/clavulanic acid, ampicillin, penicillin, ceftriaxone, clarithromycin, erythromycin, levofloxacin and trimethoprim/sulfamethoxazole) allowed, for the first time in a SOAR study, the effect of raising the dosage on susceptibility to be quantified.

CONCLUSIONS

Antibiotic susceptibility of S. pneumoniae was generally low, which is in keeping with evidence of inappropriate and high antibiotic use in Turkey. H. influenzae susceptibility was high. These data are important for empirical therapy of CA-RTIs.

Results from the Survey of Antibiotic Resistance (SOAR) 2015-17 in Latin America (Argentina, Chile and Costa Rica): data based on CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints

OBJECTIVES

To determine antibiotic susceptibility of Streptococcus pneumoniae and Haemophilus influenzae isolates from community-acquired respiratory tract infections (CA-RTIs) collected in 2015-17 from Argentina, Chile and Costa Rica.

METHODS

MICs were determined by CLSI broth microdilution and susceptibility was assessed using CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints.

RESULTS

A total of 170 S. pneumoniae and 218 H. influenzae isolates were collected at five centres in Argentina, Chile and Costa Rica in 2015-17. Small S. pneumoniae isolate numbers from Costa Rica (n = 2) meant that these could only be included in the penicillin susceptibility analysis; they were excluded from further country analyses. Around one-third of pneumococcal isolates from Argentina and two-thirds from Chile were non-susceptible to penicillin by CLSI oral or EUCAST low-dose IV breakpoints, but most (≥89%) were susceptible by CLSI IV or EUCAST high-dose breakpoints. Amongst pneumococci from Argentina, about 80% or more were susceptible to most other antibiotics except cefaclor (all breakpoints), cefixime (PK/PD breakpoints), cefuroxime (EUCAST breakpoints) and trimethoprim/sulfamethoxazole (CLSI and PK/PD breakpoints). S. pneumoniae isolates from Chile showed significantly lower susceptibility (P < 0.05) using CLSI breakpoints compared with those from Argentina for many of the antibiotics tested. Among isolates of H. influenzae from Latin America, more than 90% were susceptible to amoxicillin/clavulanic acid (high dose), cefixime, cefpodoxime, ceftriaxone and fluoroquinolones, irrespective of the breakpoints used. The application of different EUCAST breakpoints for low and higher doses for some of the antibiotics (amoxicillin, amoxicillin/clavulanic acid, ampicillin, penicillin, ceftriaxone, clarithromycin, erythromycin, levofloxacin and trimethoprim/sulfamethoxazole) allowed, for the first time in a SOAR study, the effect of raising the dosage on susceptibility to be quantified.

CONCLUSIONS

Antibiotic susceptibility of H. influenzae isolates was generally high in the Latin American countries studied; however, susceptibility profiles varied for S. pneumoniae by country and depending on the breakpoints used, especially for cefaclor. These factors are important in decision making for empirical therapy of bacterial infections.

Results from the Survey of Antibiotic Resistance (SOAR) 2016-17 in Ukraine: data based on CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints

OBJECTIVES

To determine antibiotic susceptibility of Streptococcus pneumoniae and Haemophilus influenzae isolates from community-acquired respiratory tract infections (CA-RTIs) collected in 2016-17 from Ukraine.

METHODS

MICs were determined by CLSI broth microdilution and susceptibility was assessed using CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints.

RESULTS

A total of 177 viable clinical isolates, including 78 S. pneumoniae and 99 H. influenzae, were collected. Overall, ∼98% of S. pneumoniae isolates were susceptible to penicillin by CLSI IV or EUCAST high-dose breakpoints and 73.1% were susceptible by CLSI oral or EUCAST low-dose IV breakpoints. Susceptibility rates of 76.9%-100% were observed for most antibiotics by all breakpoints except trimethoprim/sulfamethoxazole (41%-69.2%) and cefaclor, which showed the greatest difference between breakpoints: 0% by EUCAST, 28.2% by PK/PD and 73.1% by CLSI. All S. pneumoniae isolates were susceptible to amoxicillin/clavulanic acid by CLSI and PK/PD breakpoints. H. influenzae isolates were almost all β-lactamase negative (90.9%). One isolate was β-lactamase negative and ampicillin resistant (BLNAR) by CLSI and four isolates were BLNAR by EUCAST criteria. Susceptibility of isolates was high (≥90.9%) by CLSI breakpoints for all antibiotics tested except trimethoprim/sulfamethoxazole (61.6%). Susceptibility using EUCAST breakpoints was similar for ampicillin (90.9%) and amoxicillin/clavulanic acid (95%) but was low for cefuroxime (oral), where only 10.1% of isolates were susceptible. All S. pneumoniae and H. influenzae isolates were susceptible to the fluoroquinolones by all breakpoints. Susceptibility to ceftriaxone was also 100% for H. influenzae and ≥91% for S. pneumoniae isolates by all breakpoints. The application of different EUCAST breakpoints for low and higher doses for some of the antibiotics (amoxicillin, amoxicillin/clavulanic acid, ampicillin, penicillin, ceftriaxone, clarithromycin, erythromycin, levofloxacin and trimethoprim/sulfamethoxazole) allowed, for the first time in a SOAR study, the effect of raising the dosage on susceptibility to be quantified.

CONCLUSIONS

Antibiotic susceptibility in these respiratory tract pathogens was generally high in Ukraine. These data are important for empirical therapy choices in the treatment of CA-RTIs.

Results from the Survey of Antibiotic Resistance (SOAR) 2016-18 in Vietnam, Cambodia, Singapore and the Philippines: data based on CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints

OBJECTIVES

To determine antibiotic susceptibility of Streptococcus pneumoniae and Haemophilus influenzae isolates collected from community-acquired respiratory tract infections (CA-RTIs) in 2016-18 in four Asian countries.

METHODS

MICs were determined by CLSI broth microdilution and susceptibility was assessed using CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints.

RESULTS

In total, 260 S. pneumoniae and 258 H. influenzae isolates were tested. Pneumococci from Vietnam (n = 161) were the least susceptible, with rates of susceptibility >90% for fluoroquinolones by CLSI breakpoints, ∼60% for amoxicillin, amoxicillin/clavulanic acid and ceftriaxone but <14% for most other agents. Pneumococcal isolates from Cambodia (n = 48) and Singapore (n = 34) showed susceptibilities ranging from ∼30% for trimethoprim/sulfamethoxazole and oral penicillin to 100% for fluoroquinolones. Among isolates of H. influenzae from Cambodia (n = 30), the Philippines (n = 59) and Singapore (n = 80), rates of susceptibility using CLSI breakpoints were >90% for amoxicillin/clavulanic acid, cephalosporins [except cefaclor in Singapore (77.5%)], macrolides and fluoroquinolones; for isolates from Vietnam (n = 89) the rates of susceptibility were >85% only for amoxicillin/clavulanic acid (95.5%), ceftriaxone (100%) and macrolides (87.6%-89.9%). Susceptibility to other antibiotics ranged from 7.9% (trimethoprim/sulfamethoxazole) to 57.3%-59.6% (fluoroquinolones) and 70.8% (cefixime). The application of different EUCAST breakpoints for low and higher doses for some of the antibiotics (amoxicillin, amoxicillin/clavulanic acid, ampicillin, penicillin, ceftriaxone, clarithromycin, erythromycin, levofloxacin and trimethoprim/sulfamethoxazole) allowed, for the first time in a SOAR study, the effect of raising the dosage on susceptibility to be quantified. A limitation of the study was the small sample sizes and only one or two sites participating per country; however, since susceptibility data are scarce in some of the participating countries any information concerning antibiotic susceptibility is of value.

CONCLUSIONS

Antibiotic susceptibility varied across countries and species, with isolates from Vietnam demonstrating the lowest susceptibility. Knowledge of resistance patterns can be helpful for clinicians when choosing empirical therapy options for CA-RTIs.

Results from the Survey of Antibiotic Resistance (SOAR) 2015-18 in Tunisia, Kenya and Morocco: data based on CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints

OBJECTIVES

To determine antibiotic susceptibility of community-acquired respiratory tract infection (CA-RTI) isolates of Streptococcus pneumoniae and Haemophilus influenzae collected in 2015-18 from Tunisia, Kenya and Morocco.

METHODS

MICs were determined by CLSI broth microdilution and susceptibility was assessed using CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints.

RESULTS

S. pneumoniae isolates from Tunisia (n = 79), Kenya (n = 44) and Morocco (n = 19) and H. influenzae isolates (n = 74) from Tunisia only were collected and analysed. Low antibiotic susceptibility was observed in S. pneumoniae from Tunisia, with >90% susceptible only to the fluoroquinolones (all breakpoints), penicillin (CLSI IV and EUCAST high-dose) and ceftriaxone (CLSI, EUCAST high-dose and PK/PD breakpoints). In addition, isolate susceptibility in Kenya was >90% to amoxicillin and amoxicillin/clavulanic acid (CLSI and PK/PD breakpoints). Antibiotic activity was highest in Morocco, where ≥89.5% of pneumococci were susceptible to most antibiotics, excluding trimethoprim/sulfamethoxazole (68.4% by CLSI or PK/PD and 79%-84.2% by EUCAST), macrolides (79%-84.2% by all breakpoints) and cefaclor (0% by EUCAST and 52.6% by PK/PD). The majority (≥86.5%) of H. influenzae isolates from Tunisia were susceptible to most antibiotics by all available breakpoints, except ampicillin and amoxicillin (almost one-third were β-lactamase positive), trimethoprim/sulfamethoxazole (51.4%-56.8%), cefaclor (1.4% by PK/PD), cefuroxime (4.1% by EUCAST), macrolides (1.4%-2.7% by PK/PD) and cefdinir (66.2% by PK/PD). The application of different EUCAST breakpoints for low and higher doses for some of the antibiotics (amoxicillin, amoxicillin/clavulanic acid, ampicillin, penicillin, ceftriaxone, clarithromycin, erythromycin, levofloxacin and trimethoprim/sulfamethoxazole) allowed, for the first time in a SOAR study, the effect of raising the dosage on susceptibility to be quantified.

CONCLUSIONS

Low antibiotic susceptibility was observed in S. pneumoniae from Tunisia, but susceptibility was higher in isolates from Kenya and highest in those from Morocco. H. influenzae from Tunisia were highly susceptible to most antibiotics. These factors are important in decision making for empirical therapy of CA-RTIs.

Results from the Survey of Antibiotic Resistance (SOAR) 2015-17 in the Middle East (Kuwait, Lebanon and Saudi Arabia): data based on CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints

OBJECTIVES

To determine antibiotic susceptibility of Streptococcus pneumoniae and Haemophilus influenzae isolates from community-acquired respiratory tract infections (CA-RTIs) collected in 2015-17 from Kuwait, Lebanon and Saudi Arabia.

METHODS

MICs were determined by CLSI broth microdilution and susceptibility was assessed using CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints.

RESULTS

A total of 139 S. pneumoniae isolates were collected from four centres in Kuwait, Lebanon and Saudi Arabia in 2015-17 and 55 H. influenzae isolates were collected and analysed from Saudi Arabia over the same time period. Pneumococci from all three countries were commonly non-susceptible to penicillin based on CLSI oral or low-dose IV penicillin using EUCAST breakpoints (39% in Kuwait to 57.1% in Lebanon) but by CLSI IV and EUCAST high-dose breakpoints most isolates were susceptible (∼90% in Kuwait and Saudi Arabia, and 100% in Lebanon). Isolates from Lebanon were highly susceptible to most other antibiotics (>90%) except cefaclor, oral cefuroxime and cefpodoxime (EUCAST breakpoints only). Overall, susceptibility was significantly lower in Kuwait and Saudi Arabia than Lebanon. Although all H. influenzae isolates (Saudi Arabia only) were β-lactamase negative, 3.6% and 12.7% were ampicillin resistant by CLSI and EUCAST breakpoints, respectively. Otherwise susceptibility was high in H. influenzae. The application of different EUCAST breakpoints for low and higher doses for some of the antibiotics (amoxicillin, amoxicillin/clavulanic acid, ampicillin, penicillin, ceftriaxone, clarithromycin, erythromycin, levofloxacin and trimethoprim/sulfamethoxazole) allowed, for the first time in a SOAR study, the effect of raising the dosage on susceptibility to be quantified.

CONCLUSIONS

Relatively low antibiotic susceptibility was observed in S. pneumoniae from Kuwait and Saudi Arabia in contrast to Lebanon, where rates of susceptibility were generally higher. Isolates of H. influenzae from Saudi Arabia were susceptible to most antibiotics. These factors are important in decision making for empirical therapy of CA-RTIs.

Results from the Survey of Antibiotic Resistance (SOAR) 2015-17 in Pakistan: data based on CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints

OBJECTIVES

To determine antibiotic susceptibility of community-acquired respiratory tract infection (CA-RTI) isolates of Streptococcus pneumoniae and Haemophilus influenzae collected in 2015-17 from Pakistan.

METHODS

MICs were determined by CLSI broth microdilution and susceptibility was assessed using CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints.

RESULTS

A total of 94 S. pneumoniae and 122 H. influenzae isolates were collected. Susceptibility to penicillin was noted in 23.4% of the S. pneumoniae isolates by CLSI oral/EUCAST low-dose IV breakpoints, although by CLSI IV and EUCAST high-dose breakpoints all isolates were characterized as susceptible. Susceptibility to trimethoprim/sulfamethoxazole (10.6%), macrolides (33%) and cefaclor (28.7%) was low but higher susceptibility was observed to ceftriaxone (100%), amoxicillin and amoxicillin/clavulanic acid (98.9%), cefuroxime (oral, 97.9%), cefpodoxime (96.8%), fluoroquinolones (93.6%-96.8%) and cefdinir (76.6%) by CLSI breakpoints. However, using EUCAST breakpoints, susceptibility to cefpodoxime (70.2%) and cefuroxime (oral, 61.7%) was reduced. H. influenzae isolates were almost all β-lactamase negative (96.7%). Using CLSI breakpoints, ≥93.4% of isolates were susceptible to all antibiotics tested except fluoroquinolones (75.4%-77.1%) and trimethoprim/sulfamethoxazole (41%). The proportion of isolates susceptible using EUCAST breakpoints was similar or identical for penicillins, trimethoprim/sulfamethoxazole and the cephalosporins that have EUCAST breakpoints; the proportion of isolates susceptible using EUCAST breakpoints was similar or identical to that using CSLI breakpoints except for cefuroxime (oral), where only 1.6% of isolates were considered susceptible. Susceptibility of H. influenzae to fluoroquinolones was also lower by EUCAST breakpoints (33.6%-34.4%). The application of different EUCAST breakpoints for low and higher doses for some of the antibiotics (amoxicillin, amoxicillin/clavulanic acid, ampicillin, penicillin, ceftriaxone, clarithromycin, erythromycin, levofloxacin and trimethoprim/sulfamethoxazole) allowed, for the first time in a SOAR study, the effect of raising the dosage on susceptibility to be quantified.

CONCLUSIONS

Antibiotic susceptibility in these important respiratory tract pathogens varied in Pakistan based on different breakpoints. These data are important for empirical therapy choices in the treatment of CA-RTIs.

Third-generation cephalosporin resistance in clinical isolates of Enterobacterales collected between 2016-2018 from USA and Europe: genotypic analysis of β-lactamases and comparative in vitro activity of cefepime/enmetazobactam

OBJECTIVES

This study aimed to investigate third-generation cephalosporin (3GC) resistance determinants [extended-spectrum β-lactamases (ESBLs), AmpC β-lactamases and OXA-type β-lactamases] in contemporary clinical Enterobacterales isolates and to determine the in vitro activity of β-lactams and β-lactam/β-lactamase inhibitor combinations, including the investigational combination of cefepime and the novel β-lactamase inhibitor enmetazobactam.

METHODS

Antibacterial susceptibility of 7168 clinical Enterobacterales isolates obtained between 2016-2018 from North America and Europe was determined according to CLSI guidelines. Phenotypic resistance to the 3GC ceftazidime (MIC ≥ 16 µg/mL) and/or ceftriaxone (MIC ≥ 4 µg/mL) but retaining susceptibility to meropenem (MIC ≤ 1 µg/mL) was determined. β-Lactamase genotyping was performed on clinical isolates with ceftazidime, ceftriaxone, cefepime or meropenem MIC ≥ 1 µg/mL.

RESULTS

Phenotypic resistance to 3GCs occurred in 17.5% of tested isolates, whereas 2.1% of isolates were resistant to the carbapenem meropenem. Within the 3GC-resistant subgroup, 60.1% (n = 752) of isolates encoded an ESBL, 25.6% (n = 321) encoded an AmpC-type β-lactamase and 0.9% (n = 11) encoded an OXA-type β-lactamase. Susceptibility of the subgroup to piperacillin/tazobactam (57.5%) and ceftolozane/tazobactam (71.3%) was <90% based on breakpoints established by the CLSI. Projected susceptibility to cefepime/enmetazobactam was 99.6% when applying the cefepime susceptible, dose-dependent breakpoint of 8 µg/mL. Against ESBL-producing isolates (n = 801) confirmed by genotyping, only susceptibility to meropenem (96.0%) and cefepime/enmetazobactam (99.9%) exceeded 90%.

CONCLUSION

This study describes the antibacterial activity of important therapies against contemporary 3GC-resistant clinical Enterobacterales isolates and supports the development of cefepime/enmetazobactam as a carbapenem-sparing option for ESBL-producing pathogens.

1617. Mecillinam susceptibility against Enterobacterales isolated from urinary tract infections from US patients in 2018

Background

Mecillinam is a unique amidinopenicillin antibiotic, being the first and the only compound in its class. In contrast to other beta-lactams, it has a unique mechanism of action whereby it exerts its antibacterial activity through binding to penicillin binding protein 2. Pivmecillinam is the oral-prodrug of mecillinam and recommended as a first line therapy in the IDSA guidelines for uncomplicated urinary tract infections (uUTI), despite not yet being available in the USA. To support the clinical development of mecillinam and pivmecillinam in the USA for the treatment of both complicated UTI and uUTI this study investigated the activity of mecillinam against Enterobacterales isolates from the USA during 2018.

Methods

A total of 1,090 isolates from urinary tract infections from patients in the USA were tested. Activity of antibiotics was tested by CLSI methodology and susceptibility interpreted according to CLSI guidelines.

Results

Susceptibility and activity of each antibiotic are shown in the Table. Mecillinam MIC₅₀ and MIC₉₀ were 0.25 and 4 µg/mL, respectively and 94.5% of isolates were susceptible. Fosfomycin MIC₅₀ and MIC₉₀ were 2 and 32 µg/mL, respectively and 95.7% of isolates were susceptible. The other four comparator antibiotics showed MIC₉₀ values >8 µg/mL and a 70.5 – 79.9% susceptible isolates. The highest MIC₉₀ against all isolates combined was 64 µg/mL for nitrofurantoin and the highest percentage of resistance was obtained with trimethoprim-sulfamethoxazole with 29.5%. Resistance towards ceftriaxone and ciprofloxacin was 19.6% and 26.1%, respectively.

Table

Conclusion

Overall, mecillinam showed the lowest MIC₉₀ and a comparable susceptibility profile (94.5 % susceptible and 4.0 % resistant) to fosfomycin (i.e. 95.7% and 2.0% resistant) susceptible isolates). Resistance to ceftriaxone, ciprofloxacin and trimethoprim/sulfamethoxazole around or above 20% is concerning for their clinical usage to treat urinary tract infections. These encouraging susceptibility data warrant further studies to support the clinical development of mecillinam/pivmecillinam for the treatment of UTI in the USA.

Disclosures

Stephen Hawser, PhD, Tetraphase Pharmaceuticals (Scientific Research Study Investigator) Cedric Charrier, PhD, IHMA (Employee)Utility Therapeutics (Independent Contractor) Cyntia De Piano, PhD, IHMA (Employee)Utility Therapeutics (Independent Contractor) Morton Alexander, PhD, Utility Therapeutics (Employee, Shareholder) Anne Santerre Henriksen, MS, Maxel Consulting ApS (Employee)Utility Therapeutics (Independent Contractor)

1613. Global 2018 Surveillance of Eravacycline Against Gram-negative Pathogens, Including Multi-drug Resistant Isolates

Background

Eravacycline (ERV) is a fully-synthetic, fluorocycline antibacterial approved by the FDA and EMA for treatment of complicated intra-abdominal infections (cIAI) in patients ≥18 years of age. The purpose of this study was to describe the in vitro activity of ERV against Gram-negative pathogens, including multi-drug resistant (MDR) isolates, collected in 2018.

Methods

Isolates were collected during 2018 from various body sites. Minimum inhibitory concentrations (MICs) were determined by CLSI broth microdilution. Antibiotic susceptibility was determined using the most updated CLSI breakpoints, except for ERV and tigecycline (TGC) where FDA breakpoints established in 2018 and 2005 respectively, were used. MDR was defined as resistance to ≥3 antibiotics from aztreonam, a carbapenem (meropenem or ertapenem [ETP]), cefepime/cefotaxime/ceftazidime/ceftriaxone (any one), gentamicin, levofloxacin, piperacillin-tazobactam TZP, tetracycline or TGC.

Results

Summary MIC data for ERV and select comparators are shown in the Table. ERV MIC₉₀ for all-Enterobacteriaceae was 0.5 μg/ml and for MDR-Enterobacteriaceae was 1μg/ml. The susceptibilities for all-Enterobacteriaceae were 93%, 95%, 93% and 82% for ERV, TGC, ETP and TZP, respectively. ERV further demonstrated higher rates of susceptibility than ETP and TZP against MDR-Enterobateriaceae, 81% vs 71% vs 38%. ERV MIC_50/90 for carbapenem-resistant Acinetobacter baumannii (CRAB) were 4-fold lower than TGC.

Table

Conclusion

ERV in vitro activity was demonstrated and comparable susceptibility rates were observed for clinically important Gram-negative pathogens, including resistant isolates. Overall, ERV MIC₉₀ values were 2- to 8- fold lower than TGC. this study further highlights the in vitro activity of ERV against Gram-negative pathogens identified in patients with cIAI.

Disclosures

Virgil Lijfrock, PharMD, Tetraphase (Employee) Steven Morgan, PharMD, Tetraphase Pharmaceuticals (Employee) Sara Hwang, PharMD, Tetraphase Pharmaceuticals (Employee) Ekaterina Efimova, PharMD, Tetraphase Pharmaceuticals (Employee) Kenneth Lawrence, PharmD, Tetraphase Pharmaceuticals (Employee) Stephen Hawser, PhD, Tetraphase Pharmaceuticals (Scientific Research Study Investigator) Ian Morrissey, PhD, Tetraphase Pharmaceuticals (Scientific Research Study Investigator)

915. Global 2018 Surveillance of Eravacycline Against Gram-positive Pathogens, Including Resistant Isolates

Background

Eravacycline (ERV) is a fully-synthetic, fluorocycline antibacterial approved by the FDA and EMA for the treatment of complicated intra-abdominal infections (cIAI) in patients ≥18 years of age. The purpose of this study was to further monitor the in vitro activity of ERV against Gram-positive pathogens, such as Staphylococcus aureus (including methicillin-resistant S. aureus, MRSA), Enterococcus spp. (including vancomycin-resistant Enterococcus, VRE) and Streptococcus spp.

Methods

Isolates were collected globally during 2018 from various body sites. Minimum inhibitory concentrations (MICs) were determined by CLSI broth microdilution. Antibiotic susceptibility was determined using the most recent CLSI breakpoints (30th ed CLSI M100 document), except for ERV and tigecycline (TGC) where FDA breakpoints from 2018 and 2005, respectively, were applied.

Results

Summary MIC data for ERV and select comparators are shown in the Table. ERV MIC50/90 for Enterococcus spp were 0.06/0.12 μg/mL and were not affected by the presence of vancomycin resistant mechanisms. The MIC90 of ERV against VRE was 2-fold lower than TGC, at a value of 0.12 μg/mL. ERV MIC90 values for methicillin-susceptible S. aureus (MSSA) was 0.12 μg/mL and for MRSA was 0.25 μg/mL. Generally, for all pathogens, ERV MIC90 values were 2- to 4-fold lower than TGC.

Table

Conclusion

ERV in vitro activity was demonstrated for clinically important Gram-positive pathogens, including resistant isolates. Overall, ERV demonstrated lower MIC90 values than comparators for all organisms. This 2018 global surveillance highlights ERV’s utility against Gram-positive organisms and further underscores its role in cIAI, where these pathogens play a causative role.

Disclosures

Steven Morgan, PharMD, Tetraphase Pharmaceuticals (Employee) Sara Hwang, PharMD, Tetraphase Pharmaceuticals (Employee) Ekaterina Efimova, PharMD, Tetraphase Pharmaceuticals (Employee) Stephen Hawser, PhD, Tetraphase Pharmaceuticals (Scientific Research Study Investigator) Virgil Lijfrock, PharMD, Tetraphase (Employee)

Antimicrobial susceptibility monitoring of canine and feline skin and ear pathogens isolated from European veterinary clinics: results of the ComPath Surveillance programme

BACKGROUND

The ComPath project is a pan-European programme dedicated to the monitoring of antimicrobial susceptibility of canine and feline pathogens using standardized methods and centralized minimal inhibitory concentration (MIC) determination.

OBJECTIVES

To report antimicrobial susceptibilities of major pathogens isolated from nontreated animals with acute clinical signs of skin, wound or ear infections in 2013-2014.

METHODS AND MATERIALS

MICs were determined by agar dilution for commonly used drugs and interpreted using Clinical and Laboratory Standards Institute (CLSI) breakpoints, if available.

RESULTS

Of 1,676 isolates recovered, the main species isolated from dogs were Staphylococcus pseudintermedius, followed by Streptococcus spp., Pseudomonas aeruginosa and Escherichia coli. In cats, Pasteurella multocida, coagulase-negative staphylococci (CoNS) and Staphylococcus aureus were isolated most frequently. Resistance rates observed for S. pseudintermedius were <26.7% for penicillin, clindamycin and chloramphenicol, and ≤11.5% for ampicillin, amoxicillin/clavulanate, cefalexin, cefovecin, gentamicin and fluoroquinolones. For S. aureus, resistance rates ranged up to 90.9% for β-lactams, and were 19.7% for clindamycin, 27% for fluoroquinolones and 0.0-6.1% for other drugs. The mecA gene was confirmed by PCR in 10.6% of S. pseudintermedius, 11.6% of CoNS and 31.4% of S. aureus isolates. In streptococci/enterococci, resistance to penicillin, ampicillin and chloramphenicol ranged from 0.0% to 11.3%, whereas fluoroquinolone resistance ranged from 0.0% to 8.5%. For E. coli, resistance ranged from 13.8 to 15.9% for fluoroquinolones and from 86.2% to 100.0% for β-lactams. Low rates of resistance (0.0-6.3%) were observed in P. multocida, and for P. aeruginosa resistance to gentamicin was 10.3%.

CONCLUSION

Overall, antimicrobial resistance of cutaneous/otic pathogens isolated from dogs and cats was low (1-10%) to moderate (10-20%). For several pathogens, the paucity of CLSI recommended breakpoints for veterinary use is a bottleneck.