scholarly journals In Vitro Activity of Imipenem and Colistin against a Carbapenem-ResistantKlebsiella pneumoniaeIsolate Coproducing SHV-31, CMY-2, and DHA-1

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Hung-Jen Tang ◽  
Yee-Huang Ku ◽  
Mei-Feng Lee ◽  
Yin-Ching Chuang ◽  
Wen-Liang Yu

We investigated the synergism of colistin and imipenem against a multidrug-resistantK. pneumoniaeisolate which was recovered from a severe hip infection. PCR and DNA sequencing were used to characterize the outer membrane porin genes and the resistance genes mediating the commonβ-lactamases and carbapenemases. Synergism was evaluated by time-kill studies. TheblaSHV-31,blaCMY-2, andblaDHA-1were detected. Outer membrane porin genes analysis revealed loss ofompK36and frame-shift mutation ofompK35. The common carbapenemase genes were not found. Time-kill studies demonstrated that a combination of 1x MIC of colistin (2 mg/L) and 1x MIC of imipenem (8 mg/L) was synergistic and bactericidal but with inoculum effect. Bactericidal activity without inoculum effect was observed by concentration of 2x MIC of colistin alone or plus 2x MIC of imipenem. In conclusion, colistin plus imipenem could be an alternative option to treat carbapenem-resistantK. pneumoniaeinfections.

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S285-S285 ◽  
Author(s):  
Mohamad Yasmin ◽  
Steven Marshall ◽  
Michael Jacobs ◽  
Daniel D Rhoads ◽  
Laura J Rojas ◽  
...  

Abstract Background Vaborbactam is a cyclic boronic acid β-lactamase inhibitor (BLI) developed to potently inhibit Ambler class A&C enzymes, including KPC carbapenemases. Metallo-β-lactamases (MBL) and some Class D oxacillinases (OXA) are not inactivated by vaborbactam. Meropenem-vaborbactam (MV) was recently approved for the treatment of carbapenem-resistant Enterobacteriaceae complicated urinary tract infections. Recent studies have identified outer membrane porin (Ompk35 and -36) mutations in Klebsiella pneumoniae (KP) as a mechanism of decreased susceptibility to MV. We evaluated the activity of MV against a historical cohort of KP clinical isolates with these porin gene mutations. Methods WGS of carbapenem-resistant KP clinical isolates was performed and those harboring mutations in Ompk35 or Ompk36 were selected for testing. Strain KP ATCC BAA-1705 was used as a positive control. Meropenem and MV minimum inhibitory concentrations (MIC) were determined by broth microdilution (BMD) in custom 96-well plates (ThermoFisher Scientific) with a constant 8 µg/mL vaborbactam concentration. The MIC of ceftazidime–avibactam (CZA) was determined by standard BMD reference methods and interpreted according to CLSI criteria. Results A total of 105 KP isolates with either partial or complete mutations in outer membrane porin genes were included in the analysis. All isolates were resistant to Meropenem. The median MV MIC was 0.03 µg/mL (range, 0.015 to >16 µg/mL). Eleven isolates (10.4%) were resistant to MV. Sixteen additional isolates (16.1%) demonstrated higher than expected MV MICs ranging from 1 to 4 µg/mL. Only 1/11 resistant isolates harbored a gene for MBL production. Gene mutations in blaKPC were not detected. See Table 1 for characteristics of resistant isolates. Conclusion Resistance and decreased susceptibility to MV is demonstrated in a historical cohort of KP clinical isolates dating back to 2013. WGS reliably identifies porin variants secondary to gene mutations in Ompk35 and Ompk36 as the underlying mechanism of decreased susceptibility. CZA appears to retain activity against these isolates. Caution should be exercised regarding the empiric use of MV against increasingly resistant KP as a result of non-β-lactamase-mediated mechanisms. Disclosures All authors: No reported disclosures.


Antibiotics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 885
Author(s):  
Soraya Herrera-Espejo ◽  
Tania Cebrero-Cangueiro ◽  
Gema Labrador-Herrera ◽  
Jerónimo Pachón ◽  
María Eugenia Pachón-Ibáñez ◽  
...  

Multidrug-resistant (MDR) Pseudomonas aeruginosa is a public health problem causing both community and hospital-acquired infections, and thus the development of new therapies for these infections is critical. The objective of this study was to analyze in vitro the activity of pentamidine as adjuvant in combinations to antibiotics against seven clinical P. aeruginosa strains. The Minimum Inhibitory Concentration (MIC) was determined following standard protocols, and the results were interpreted according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints; however, the gentamicin activity was interpreted according to the Clinical and Laboratory Standards Institute (CLSI) recommendations. The bactericidal in vitro activity was studied at 1×MIC concentrations by time–kill curves, and also performed in three selected strains at 1/2×MIC of pentamidine. All studies were performed in triplicate. The pentamidine MIC range was 400–1600 μg/mL. Four of the strains were MDR, and the other three were resistant to two antibiotic families. The combinations of pentamidine at 1×MIC showed synergistic activity against all the tested strains, except for pentamidine plus colistin. Pentamidine plus imipenem and meropenem were the combinations that showed synergistic activity against the most strains. At 1/2×MIC, pentamidine plus antibiotics were synergistic with all three analyzed strains. In summary, pentamidine in combination with antibiotics showed in vitro synergy against multidrug-resistant P. aeruginosa clinical strains, which suggests its possible use as adjuvant to antibiotics for the therapy of infections from MDR P. aeruginosa.


2021 ◽  
Vol 12 ◽  
Author(s):  
Yanqin Huang ◽  
Tiffany Wu ◽  
Omar Perez ◽  
Amisha P. Rana ◽  
Liang Chen ◽  
...  

Ceftazidime/avibactam is an important treatment option for infections caused by Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp), however, resistance can emerge during treatment. The objective of the study was to define the ceftazidime/avibactam concentrations required to suppress bacterial regrowth in ceftazidime/avibactam susceptible isolates and identify active therapies against ceftazidime/avibactam-resistant KPC-Kp. Time-kill assays were performed against twelve ST258 KPC-Kp isolates that harbored blaKPC–2 or blaKPC–3. Nine KPC-Kp isolates (KPC-Kp 5A, 6A, 7A, 8A, 9A, 24A, 25A, 26A, and 27A) were susceptible to ceftazidime/avibactam, two (KPC-Kp 6B and 7B) were ceftazidime/avibactam resistant and meropenem susceptible, and one (KPC-Kp 1244) was resistant to both ceftazidime/avibactam and meropenem. Sequencing of the blaKPC genes revealed mutations in KPC-Kp 6B (D179Y substitution) and 7B (novel 21 base pair deletion) that both affected the Ω-loop encoding portion of the gene. Time-kill assays showed that against ceftazidime/avibactam-susceptible KPC-Kp, ceftazidime/avibactam concentrations ≥40/7.5 mg/L caused mean 5.42 log10CFU/mL killing and suppressed regrowth. However, regrowth occurred for some KPC-Kp isolates with a ceftazidime/avibactam concentration of 20/3.75 mg/L. Against ceftazidime/avibactam-resistant and meropenem-susceptible KPC-Kp 6B and 7B, bactericidal activity and synergy was observed for ceftazidime/avibactam in combination with meropenem ≤3.125 mg/L, while meropenem concentrations ≥50 mg/L were bactericidal as monotherapy. In contrast, clinically achievable concentrations of ceftazidime/avibactam were bactericidal against KPC-Kp 1244, which was ceftazidime/avibactam-resistant and meropenem-resistant due to outer membrane porin mutations and elevated blaKPC expression. Achieving high ceftazidime/avibactam concentrations may help to suppress bacterial regrowth in the presence of ceftazidime/avibactam. The optimal treatment approach for ceftazidime/avibactam-resistant KPC-Kp likely depends on the mechanism of resistance. Additional studies are warranted to confirm these findings.


Antibiotics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 912
Author(s):  
Taeeun Kim ◽  
Seung Cheol Lee ◽  
Moonsuk Bae ◽  
Heungsup Sung ◽  
Mi-Na Kim ◽  
...  

Ceftazidime-avibactam (CAZ-AVI) and aztreonam-avibactam (AZT-AVI) are novel antibiotic combinations active against multidrug-resistant Gram-negative pathogens. This study aimed to evaluate their in vitro activities and inoculum effects in carbapenem-resistant Enterobacterales (CRE), including carbapenemase-producing (CP)-CRE and non-CP-CRE. A total of 81 independent clinical isolates of carbapenem-resistant Escherichia coli and Klebsiella pneumoniae were collected. CAZ-AVI and AZT-AVI minimal inhibitory concentrations (MICs) were evaluated by broth microdilution using standard and high inocula. The inoculum effect was defined as an ≥8-fold increase in MIC with high inoculum. Phenotypic determination of β-lactam resistance mechanism and PCR for carbapenemase genes were performed. Of the 81 CRE isolates, 35 (43%) were CP-CRE. Overall, 73% of the isolates were susceptible to CAZ-AVI, and 95% had low AZT-AVI MICs (≤8 µg/mL). The MIC50/MIC90s of CAZ-AVI and AZT-AVI were 4/≥512 µg/mL and 0.5/4 µg/mL, respectively. CAZ-AVI was more active against non-CP-CRE than against CP-CRE (susceptibility 80% vs. 63%, p = 0.08; MIC50/MIC90, 2/16 μg/mL vs. 4/≥512 μg/mL), whereas AZT-AVI was more active against CP-CRE (MIC50/MIC90, 0.25/1 μg/mL vs. 0.5/8 μg/mL). All four isolates with high AZT-AVI MIC (≥16 μg/mL) were resistant to CAZ-AVI, but only 18% (4/22) of CAZ-AVI-resistant isolates had high AZT-AVI MIC. The rates of the inoculum effect for CAZ-AVI and AZT-AVI were 18% and 47%, respectively (p < 0.001). Interestingly, the frequency of the AZT-AVI inoculum effect was higher in K. pneumoniae than E. coli (64% vs. 8%, p < 0.001). AZT-AVI is more active against CRE than CAZ-AVI, even in CP-CRE and CAZ-AVI-resistant isolates. The presence of a substantial inoculum effect may contribute to clinical failure in high-inoculum infections treated with AZT-AVI.


2020 ◽  
Vol 75 (7) ◽  
pp. 1840-1849 ◽  
Author(s):  
Mercedes Delgado-Valverde ◽  
M del Carmen Conejo ◽  
Lara Serrano ◽  
Felipe Fernández-Cuenca ◽  
Álvaro Pascual

Abstract Background Cefiderocol is a novel siderophore cephalosporin, developed for activity against MDR Gram-negative bacilli (MDR-GNB). Objectives To assess the in vitro antibacterial activity of cefiderocol against a collection of MDR-GNB clinical isolates from hospitals in southern Spain. Methods Two hundred and thirty-one isolates of successful clones were tested: 125 Enterobacterales (121 ESBL- and/or carbapenemase-producing Klebsiella pneumoniae and 4 carbapenemase-producing Enterobacter cloacae), 80 Acinetobacter baumannii, 6 Pseudomonas aeruginosa and 20 Stenotrophomonas maltophilia. Ceftolozane/tazobactam, ceftazidime, ceftazidime/avibactam, cefepime, aztreonam, meropenem, amikacin, ciprofloxacin, colistin and tigecycline were used as comparators against Enterobacterales, P. aeruginosa and A. baumannii. Minocycline, levofloxacin and trimethoprim/sulfamethoxazole were studied against S. maltophilia instead of aztreonam, ciprofloxacin and cefepime. MICs were determined by broth microdilution according to CLSI guidelines. MIC determination was performed in CAMHB for all antimicrobials except cefiderocol, where iron-depleted CAMHB was used. Results Cefiderocol showed potent in vitro activity against the isolates analysed. MIC50 and MIC90 values were in the ranges 0.125–8 mg/L and 0.5–8 mg/L, respectively, and 98% of isolates were inhibited at ≤4 mg/L. Only five isolates showed cefiderocol MICs of &gt;4 mg/L: three ST2/OXA-24/40-producing A. baumannii, one ST114/VIM-1-producing E. cloacae and one ST114/VIM-1 + OXA-48-producing E. cloacae. All KPC-3-producing K. pneumoniae were susceptible to cefiderocol, even those resistant to ceftazidime/avibactam. P. aeruginosa isolates showed cefiderocol MICs of &lt;4 mg/L, including those resistant to ceftolozane/tazobactam. S. maltophilia isolates displayed cefiderocol MICs of &lt;4 mg/L, including those resistant to levofloxacin and/or trimethoprim/sulfamethoxazole. Conclusions Cefiderocol showed excellent activity against MDR-GNB, including carbapenem-resistant isolates, and was the most active antimicrobial tested against this collection.


2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S721-S721
Author(s):  
Mark Estabrook ◽  
Krystyna Kazmierczak ◽  
Francis Arhin ◽  
Daniel F Sahm

Abstract Background Hypervirulent Klebsiella pneumoniae (hvKp), unlike classical K. pneumoniae (cKp), are often responsible for community-acquired infections in otherwise healthy individuals. The acquisition of hypervirulence genes by sequence type 11 (ST11) carbapenem-resistant (CR) Kp endemic in Asia is a grave threat. Aztreonam-avibactam (ATM-AVI) is a monobactam combined with a β-lactamase inhibitor for the treatment of infections caused by Enterobacterales isolates that carry Class A, B, C and some Class D β-lactamases. Methods 487 K. pneumoniae isolates were collected from 17 sites in China in 2019 as a part of the ATLAS global surveillance study. 220 isolates with MICs &gt;1 µg/ml to meropenem (MEM), ceftazidime or ATM were selected for whole genome sequencing (Illumina Hiseq 2x150 bp reads). Analyses were carried out using the CLC Genomics Workbench (Qiagen). Presence of the aerobactin synthesis locus differentiated hvKp and cKp. Antimicrobial susceptibility was determined by CLSI broth microdilution. Results Of the 487 isolates, MIC90 values for ATM-AVI (0.5 µg/ml; Table) were lower than those for any comparator tested, with only two isolates testing with MIC &gt;4 µg/ml. Of the isolates sequenced, 82/220 (37.3%) were ST11. 53/82 (64.6%) of these ST11 isolates were hvKp (ATM-AVI, MIC90 1 µg/ml; range, 0.25-4 µg/ml) and showed percentages of susceptibility &lt; 90% to three last-line agents (0% MEM-susceptible (S); 18.9% amikacin (AMK)-S; 88.7% tigecycline (TGC)-S). Isolates of other STs (Non-ST11) were less frequently identified as hvKp (24/138, 17.4%) and more Non-ST-11 hvKp and cKp alike were S to MEM and AMK relative to isolates of ST11 (75.0-86.8% MEM-S; 83.3-96.5% AMK-S). Likewise, the ATM-AVI MIC90 value (0.25 µg/ml) was 4-fold lower for Non-ST11 isolates. Results Table Conclusion CR ST11 hvKp represented at least 10.9% of the collected Kp isolates. ATM-AVI retained potent in vitro activity against these isolates which displayed resistance to a range of last-line agents. CST and TGC also displayed some activity but are limited in utility due to nephrotoxicity and poor accumulation in blood, respectively. The spread of virulence factors leading to the complicated clinical presentation of hvKp infection into multidrug-resistant lineages warrants continued surveillance. Disclosures Mark Estabrook, PhD, IHMA (Employee)Pfizer, Inc. (Independent Contractor) Krystyna Kazmierczak, PhD, IHMA (Employee)Pfizer, Inc. (Independent Contractor) Francis Arhin, PhD, Pfizer, Inc. (Employee) Daniel F. Sahm, PhD, IHMA (Employee)Pfizer, Inc. (Independent Contractor)


2017 ◽  
Vol 61 (4) ◽  
Author(s):  
Patrick Grohs ◽  
Gary Taieb ◽  
Philippe Morand ◽  
Iheb Kaibi ◽  
Isabelle Podglajen ◽  
...  

ABSTRACT Ceftolozane-tazobactam was tested against 58 multidrug-resistant nonfermenting Gram-negative bacilli (35 Pseudomonas aeruginosa, 11 Achromobacter xylosoxydans, and 12 Stenotrophomonas maltophilia isolates) isolated from cystic fibrosis patients and was compared to ceftolozane alone, ceftazidime, meropenem, and piperacillin-tazobactam. Ceftolozane-tazobactam was the most active agent against P. aeruginosa but was inactive against A. xylosoxydans and S. maltophilia. In time-kill experiments, ceftolozane-tazobactam had complete bactericidal activity against 2/6 clinical isolates (33%).


2018 ◽  
Vol 5 (suppl_1) ◽  
pp. S7-S8
Author(s):  
Tiffany R Keepers ◽  
Deborah S Cebrik ◽  
Daniel J Cloutier ◽  
Allison Komirenko ◽  
Lynn Connolly ◽  
...  

Abstract Background PLZ is a next-generation aminoglycoside (AG) that is structurally protected from common AG-modifying enzymes (AMEs) in Enterobacteriaceae and with in vitro activity against multidrug-resistant Enterobacteriaceae, including ESBL-producing, AG-resistant, and carbapenem-resistant isolates. We report microbiological outcomes in the EPIC study, including outcomes for resistant pathogens and by the PLZ MIC. Methods EPIC was a multinational, randomized, double-blind study in hospitalized patients with cUTI or AP. Patients received IV PLZ (15 mg/kg q24h) or IV MEM (1 g q8h) for 4–7 days, followed by optional oral therapy, for a total of 7–10 days of therapy. The extended mMITT population included patients with ≥1 qualifying baseline pathogen (≥105 CFU/mL urine) who received study drug. Microbiological outcomes were assessed at TOC (day 15–19). Isolate identification and susceptibility testing were conducted by a central laboratory. Whole-genome sequencing was used to identify AME and β-lactamase genes. Results Of 609 patients enrolled, 407 (66.8%) were included in the extended mMITT population. The most common uropathogen was Escherichia coli (63.4%) followed by Klebsiella pneumoniae (19.7%). PLZ and MEM MIC50/90 for Enterobacteriaceae were 0.5/2 μg/mL (range: ≤0.06–&gt;128 mg/mL) and 0.015/0.06 mg/mL (range: ≤0.004–128 mg/mL), respectively. ESBL and AG-NS phenotypes were found in 29% and 27% of isolates, respectively. Genotyping detected β-lactamase and AME genes in 32.5% and 36.8% of isolates, respectively, most commonly blaCTX-M-15 (n = 98), blaOXA-1/OXA-30 (n = 82), aac(6′)Ib-cr (n = 79), and aac(3)-IIa (n = 56). Rates of microbiological eradication are shown in Table 1. All Enterobacteriaceae in the PLZ group with a PLZ MIC of 4 µg/mL (6/6) were eradicated at TOC (Table 2). Across 49 patients with concurrent bacteremia, 100% (27/27) and 96% (24/25) of Enterobacteriaceae were cleared from the blood at TOC in the PLZ and MEM groups, respectively. Conclusion PLZ demonstrated comparable or higher microbiological eradication rates compared with MEM for common Gram-negative uropathogens, including resistant pathogens. The results support PLZ as a potential treatment option for cUTI, including AP, caused by Enterobacteriaceae with PLZ MICs of ≤4 mg/mL. Disclosures T. R. Keepers, Achaogen, Inc.: Employee, Salary. D. S. Cebrik, Achaogen, Inc.: Employee, Salary. D. J. Cloutier, Achaogen, Inc.: Employee and Shareholder, Salary. A. Komirenko, Achaogen, Inc.: Employee and Shareholder, Salary. L. Connolly, Achaogen, Inc.: Consultant, Consulting fee. K. Krause, Achaogen, Inc.: Employee, Salary.


2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S124-S124
Author(s):  
Meredith Hackel ◽  
Mark G G Wise ◽  
Daniel F Sahm

Abstract Background Taniborbactam is a novel cyclic boronate-based broad-spectrum β-lactamase inhibitor (BLI) with potent and selective inhibitory activity against both serine- and metallo-β-lactamases (MBLs). Taniborbactam restores the activity of cefepime (FEP) against many multidrug resistant organisms, including cephalosporin- and carbapenem-resistant Enterobacterales and Pseudomonas aeruginosa (PA). We evaluated the in vitro activity of the investigational combination cefepime-taniborbactam and comparators against clinical isolates of PA collected during a 2018-2020 surveillance. Methods MICs of FEP with taniborbactam fixed at 4 µg/mL (FTB) and comparators were determined against 3,219 PA collected from 221 sites in 52 countries in 2018-2020. Resistant phenotypes were based on 2021 CLSI breakpoints. Acquired β-lactamase (BL) genes were identified via PCR/Sanger sequencing or whole-genome sequencing (WGS) for 516 isolates with meropenem (MEM) MIC ≥8 µg/mL, and for 94 randomly selected isolates with FEP or ceftazidime MIC ≥16 µg/mL. 186 isolates with FTB MIC ≥16 µg/mL, 16 with FTB MIC=8 µg/mL and one with FTB MIC=4 µg/mL were subjected to WGS. Results Overall, 28.7%, 26.2% and 20.3% of PA isolates were nonsusceptible (NS) to piperacillin-tazobactam (TZP), MEM or FEP, respectively (Table). FTB demonstrated potent activity (MIC50/90, 2/8 µg/mL; 94.2% inhibited at ≤8 µg/mL) against PA overall and inhibited between 63.4% (ceftazidime-avibactam [CZA] NS) and 82.1% (TZP NS) of isolates in the NS subsets compared to 0% to 69.1% S for comparators. Against the 111 strains carrying VIM or NDM MBL genes, 67.6% had FTB MICs ≤8 µg/mL, with 11.7% having FTB MICs of 16 µg/mL. Plausible explanations for elevated FTB MICs included IMP MBL genes, penicillin binding protein 3 variations, and/or possible efflux pump up-regulation. Conclusion FTB demonstrated potent in vitro activity against PA with different resistance profiles, including NS to FEP, MEM, and TZP, and to the BL/BLI combinations CZA, ceftolozane-tazobactam, and meropenem-vaborbactam. FTB was the most active agent tested against PA harboring VIM and NDM MBLs. These findings support the continued development of FTB as a potential new treatment option for challenging infections due to MDR PA. Disclosures Meredith Hackel, PhD MPH, IHMA (Employee)Pfizer, Inc. (Independent Contractor) Mark G G. Wise, PhD, IHMA (Employee)Pfizer, Inc. (Independent Contractor) Daniel F. Sahm, PhD, IHMA (Employee)Pfizer, Inc. (Independent Contractor)


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