scholarly journals Molecular Characterization of Baseline Enterobacterales and Pseudomonas aeruginosa Isolates from a Phase 3 Nosocomial Pneumonia (ASPECT-NP) Clinical Trial

2020 ◽  
pp. AAC.02461-20
Author(s):  
Mariana Castanheira ◽  
Matthew G. Johnson ◽  
Brian Yu ◽  
Jennifer A. Huntington ◽  
Patricia Carmelitano ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Pseudomonas Aeruginosa ◽  
Nosocomial Pneumonia ◽  
Resistance Mechanisms ◽  
Quantitative Real Time Pcr ◽  
Phase 3 ◽  
Genes Encoding ◽  
Elevated Expression ◽  
Encoding Genes

We evaluated β-lactam-resistant Enterobacterales species and Pseudomonas aeruginosa baseline lower respiratory tract isolates collected during the ASPECT-NP phase 3 clinical trial evaluating the safety and efficacy of ceftolozane-tazobactam compared with meropenem for treatment of ventilated nosocomial pneumonia in adults. Isolates were subjected to whole genome sequencing, quantitative real-time PCR for quantification of the expression levels of β-lactamase and efflux genes, and Western blot analysis for detection of OprD (P. aeruginosa only). ESBL genes were detected in 168 of 262 Enterobacterales isolates and among these blaCTXM-15 was the most common, detected in 125 isolates. Sixty-one Enterobacterales carried genes encoding carbapenemases while 33 isolates did not carry ESBLs or carbapenemases. Carbapenemase-producing isolates carried mainly NDM and OXA-48 variants, with ceftolozane-tazobactam MIC values ranging from 4 to 128 μg/mL. Most ceftolozane-tazobactam-nonsusceptible Enterobacterales isolates that did not carry carbapenemases were K. pneumoniae that exhibited disrupted OmpK35, specific mutations in OmpK36, and, in some isolates, elevated expression of blaCTXM-15. Among 89 P. aeruginosa isolates, carbapenemases and ESBL-encoding genes were observed among 12 and 22 isolates, respectively. P. aeruginosa isolates without acquired β-lactamases displaying elevated expression of AmpC (14 isolates), elevated expression of efflux pumps (11 isolates), and/or decrease or loss of OprD (22 isolates) were susceptible to ceftolozane-tazobactam. Ceftolozane-tazobactam was active against >75% of the Enterobacterales isolates from the ASPECT-NP trial that did not carry carbapenemases. K. pneumoniae resistant to ceftolozane-tazobactam might represent a challenge for treatment due to its multiple resistance mechanisms. Ceftolozane-tazobactam was among the agents displaying the greatest activity against P. aeruginosa isolates.

scholarly journals 624. Molecular Characterization of Baseline Enterobacteriaceae and Pseudomonas aeruginosa from a Phase 3 Nosocomial Pneumonia (ASPECT-NP) Clinical Trial

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S289-S290
Author(s):  
Mariana Castanheira ◽  
Matthew G Johnson ◽  
Brian Yu ◽  
Jennifer A Huntington ◽  
Patricia Carmelitano ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Nosocomial Pneumonia ◽  
Efflux Pump ◽  
Multicenter Trial ◽  
Rt Pcr ◽  
Phase 3 ◽  
Double Blind ◽  
Esbl Gene ◽  
Organism Identification

Abstract Background ASPECT-NP, a phase 3, randomized, double-blind, multicenter trial, evaluated ceftolozane/tazobactam (C/T) 3 g q8h vs. meropenem 1 g q8h for 8–14 days in adults for treatment of ventilated nosocomial pneumonia. Baseline Gram-negative (GN) isolates from patients were tested for mechanisms of resistance. Methods Lower respiratory tract (LRT) isolates were sent to a central laboratory for organism identification and susceptibility. Of 664 total Enterobacteriaceae (ENT) and Pseudomonas aeruginosa (PsA) isolates, 351 (53%) were nonsusceptible to broad-spectrum cephalosporins and/or carbapenems and underwent whole-genome sequencing, quantitative RT–PCR, and western blot analysis. ENT isolates were tested for the presence of acquired β-lactamase genes and AmpC levels (selected species). PsA isolates were tested for acquired β-lactamase genes, AmpC (PDC) levels, efflux pump expression, and OprD loss. Results Of 262 ENT isolates, 114 (44%) were susceptible to C/T (MIC ≤2 µg/mL). An extended-spectrum β-lactamase (ESBL) gene was carried by 89 (78%) of the C/T-susceptible isolates. Of 148 C/T-nonsusceptible (C/T-NS) isolates, 87 (59%) were carbapenemase negative, and the majority 135 (91%) also carried an ESBL gene. The most common ESBL was blaCTX-M15 with blaOXA-1 and blaOXA-30. Klebsiella pneumoniae often displayed higher C/T MICs compared with other species carrying the same resistance genes. Among all C/T-NS isolates, 61 (41%) were carbapenemase positive, most commonly K. pneumoniae carrying blaOXA-48, blaNDM-1, and blaNDM-5. Of 89 PsA isolates, 58 (65%) were susceptible to C/T (MIC ≤4 µg/mL), despite elevated AmpC expression, efflux pumps, or loss of OprD; only 5 isolates had an acquired β-lactamase. Of the 31 C/T-NS PsA isolates, only 12 (39%) were carbapenemase positive and carried blaVIM or blaGES; isolates carrying blaGES had lower C/T MICs (8–32 µg/mL) compared with blaVIM (MIC > 128 µg/mL). PDC alleles were similar in isolates with high and low C/T MICs. Conclusion In baseline GN LRT isolates from ASPECT-NP, the most common ESBL detected in ENT was blaCTX-M15; carbapenemases were uncommon. There was no correlation of ESBL phenotype to C/T susceptibility among ENT, nor of PDC allele to C/T susceptibility among PsA. Disclosures All authors: No reported disclosures.

scholarly journals Molecular characterization of clinical carbapenem-resistant Enterobacterales from Qatar

2021 ◽  
Author(s):  
Fatma Ben Abid ◽  
Clement K. M. Tsui ◽  
Yohei Doi ◽  
Anand Deshmukh ◽  
Christi L. McElheny ◽  
...  
Keyword(s):  
Common Species ◽  
Clinical Samples ◽  
Whole Genome ◽  
E Coli ◽  
Carbapenem Resistant ◽  
Genes Encoding ◽  
Encoding Genes ◽  
Sequence Types ◽  
Common Sequence

AbstractOne hundred forty-nine carbapenem-resistant Enterobacterales from clinical samples obtained between April 2014 and November 2017 were subjected to whole genome sequencing and multi-locus sequence typing. Klebsiella pneumoniae (81, 54.4%) and Escherichia coli (38, 25.5%) were the most common species. Genes encoding metallo-β-lactamases were detected in 68 (45.8%) isolates, and OXA-48-like enzymes in 60 (40.3%). blaNDM-1 (45; 30.2%) and blaOXA-48 (29; 19.5%) were the most frequent. KPC-encoding genes were identified in 5 (3.6%) isolates. Most common sequence types were E. coli ST410 (8; 21.1%) and ST38 (7; 18.4%), and K. pneumoniae ST147 (13; 16%) and ST231 (7; 8.6%).

Molecular mechanisms driving the in vivo development of OXA-10-mediated resistance to ceftolozane/tazobactam and ceftazidime/avibactam during treatment of XDR Pseudomonas aeruginosa infections

2020 ◽  
Vol 76 (1) ◽  
pp. 91-100
Author(s):  
Jorge Arca-Suárez ◽  
Cristina Lasarte-Monterrubio ◽  
Bruno-Kotska Rodiño-Janeiro ◽  
Gabriel Cabot ◽  
Juan Carlos Vázquez-Ucha ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Molecular Mechanisms ◽  
Genomic Analysis ◽  
Resistance Mechanisms ◽  
Comparative Genomic ◽  
Development Of Resistance ◽  
Structural Impact ◽  
Genetic Context

Abstract Background The development of resistance to ceftolozane/tazobactam and ceftazidime/avibactam during treatment of Pseudomonas aeruginosa infections is concerning. Objectives Characterization of the mechanisms leading to the development of OXA-10-mediated resistance to ceftolozane/tazobactam and ceftazidime/avibactam during treatment of XDR P. aeruginosa infections. Methods Four paired ceftolozane/tazobactam- and ceftazidime/avibactam-susceptible/resistant isolates were evaluated. MICs were determined by broth microdilution. STs, resistance mechanisms and genetic context of β-lactamases were determined by genotypic methods, including WGS. The OXA-10 variants were cloned in PAO1 to assess their impact on resistance. Models for the OXA-10 derivatives were constructed to evaluate the structural impact of the amino acid changes. Results The same XDR ST253 P. aeruginosa clone was detected in all four cases evaluated. All initial isolates showed OprD deficiency, produced an OXA-10 enzyme and were susceptible to ceftazidime, ceftolozane/tazobactam, ceftazidime/avibactam and colistin. During treatment, the isolates developed resistance to all cephalosporins. Comparative genomic analysis revealed that the evolved resistant isolates had acquired mutations in the OXA-10 enzyme: OXA-14 (Gly157Asp), OXA-794 (Trp154Cys), OXA-795 (ΔPhe153-Trp154) and OXA-824 (Asn143Lys). PAO1 transformants producing the evolved OXA-10 derivatives showed enhanced ceftolozane/tazobactam and ceftazidime/avibactam resistance but decreased meropenem MICs in a PAO1 background. Imipenem/relebactam retained activity against all strains. Homology models revealed important changes in regions adjacent to the active site of the OXA-10 enzyme. The blaOXA-10 gene was plasmid borne and acquired due to transposition of Tn6746 in the pHUPM plasmid scaffold. Conclusions Modification of OXA-10 is a mechanism involved in the in vivo acquisition of resistance to cephalosporin/β-lactamase inhibitor combinations in P. aeruginosa.

Nucleotide sequences and characterization of genes encoding naphthalene upper pathway of pseudomonas aeruginosa PaK1 and Pseudomonas putida OUS82

1999 ◽  
Vol 87 (6) ◽  
pp. 721-731 ◽  
Author(s):  
Noboru Takizawa ◽  
Toshiya Iida ◽  
Takashi Sawada ◽  
Kazuhiro Yamauchi ◽  
Yue-Wu Wang ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Pseudomonas Putida ◽  
Nucleotide Sequences ◽  
Genes Encoding

scholarly journals β-Lactamase Characterization of Baseline Pseudomonas aeruginosa (PSA) from Five Ceftazidime-Avibactam (CAZ-AVI) Phase 3 Clinical Trials

2017 ◽  
Vol 4 (suppl_1) ◽  
pp. S130-S130 ◽  
Author(s):  
Rodrigo E Mendes ◽  
Mariana Castanheira ◽  
Leah N Woosley ◽  
Gregory G Stone ◽  
Robert Mclaughlin ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Clinical Trials ◽  
Phase 3

scholarly journals Problematic clinical isolates of Pseudomonas aeruginosa from the university hospitals in Sofia, Bulgaria: current status of antimicrobial resistance and prevailing resistance mechanisms

2007 ◽  
Vol 56 (7) ◽  
pp. 956-963 ◽  
Author(s):  
Tanya Strateva ◽  
Vessela Ouzounova-Raykova ◽  
Boyka Markova ◽  
Albena Todorova ◽  
Yulia Marteva-Proevska ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antimicrobial Agents ◽  
Carbapenem Resistance ◽  
Multidrug Resistant ◽  
Resistance Mechanisms ◽  
Clinical Isolates ◽  
Current Status ◽  
University Hospitals ◽  
Active Efflux ◽  
Genes Encoding

A total of 203 clinical isolates of Pseudomonas aeruginosa was collected during 2001–2006 from five university hospitals in Sofia, Bulgaria, to assess the current levels of antimicrobial susceptibility and to evaluate resistance mechanisms to antipseudomonal antimicrobial agents. The antibiotic resistance rates against the following antimicrobials were: carbenicillin 93.1 %, azlocillin 91.6 %, piperacillin 86.2 %, piperacillin/tazobactam 56.8 %, ceftazidime 45.8 %, cefepime 48.9 %, cefpirome 58.2 %, aztreonam 49.8 %, imipenem 42.3 %, meropenem 45.5 %, amikacin 59.1 %, gentamicin 79.7 %, tobramycin 89.6 %, netilmicin 69.6 % and ciprofloxacin 80.3 %. A total of 101 of the studied P. aeruginosa isolates (49.8 %) were multidrug resistant. Structural genes encoding class A and class D β-lactamases showed the following frequencies: bla VEB-1 33.1 %, bla PSE-1 22.5 %, bla PER-1 0 %, bla OXA-groupI 41.3 % and bla OXA-groupII 8.8 %. IMP- and VIM-type carbapenemases were not detected. In conclusion, the studied clinical strains of P. aeruginosa were problematic nosocomial pathogens. VEB-1 extended-spectrum β-lactamases appear to have a significant presence among clinical P. aeruginosa isolates from Sofia. Carbapenem resistance was related to non-enzymic mechanisms such as a deficiency of OprD proteins and active efflux.

Sign in / Sign up

Export Citation Format

Share Document