In-vitro selection of porin-deficient mutants of two strains of Klebsiella pneumoniae with reduced susceptibilities to meropenem, but not to imipenem

ABSTRACT In vitro selection of mutants with decreased susceptibility to ertapenem was performed using Escherichia coli and Klebsiella pneumoniae clinical strains producing either the bla CTX-M-2, bla CTX-M-3, bla CTX-M-9, or bla CTX-M-15 gene. Frequencies of mutants with decreased susceptibilities to ertapenem were similar for all β-lactamases expressed.

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In vitro selection of aztreonam/avibactam resistance in dual-carbapenemase-producing Klebsiella pneumoniae

Journal of Antimicrobial Chemotherapy ◽

10.1093/jac/dkz468 ◽

2019 ◽

Vol 75 (3) ◽

pp. 559-565 ◽

Cited By ~ 6

Author(s):

Siqiang Niu ◽

Jie Wei ◽

Chunhong Zou ◽

Kalyan D Chavda ◽

Jingnan Lv ◽

...

Keyword(s):

Klebsiella Pneumoniae ◽

In Vitro Selection ◽

Fold Increase ◽

Single Step ◽

Mutant Selection ◽

Microdilution Method ◽

Broth Microdilution Method ◽

Resistant Mutants ◽

Selection Of

Abstract Objectives To examine the in vitro selection of aztreonam/avibactam resistance among MBL-producing Klebsiella pneumoniae and to understand the mechanism of increased resistance. Methods The MICs of aztreonam were determined with and without avibactam (4 mg/L) using a broth microdilution method. Single-step and multi-step mutant selection was conducted on five MBL-producing K. pneumoniae strains, including two dual carbapenemase producers. Genomic sequencing and gene cloning were performed to investigate the mechanism of increased resistance. Results We examined the MICs for 68 MBL-producing K. pneumoniae isolates, including 13 dual carbapenemase producers. Compared with aztreonam alone, the addition of avibactam (4 mg/L) reduced the MICs for all isolates by >128-fold, with MIC50 and MIC90 values of 0.25 and 1 mg/L, respectively. One NDM-1-, OXA-48-, CTX-M-15- and CMY-16-positive ST101 K. pneumoniae strain was selected to be resistant to aztreonam/avibactam, with a >16-fold increase in MIC (>128 mg/L). WGS revealed that the resistant mutants lost the blaNDM-1 gene, but acquired amino acid substitutions in CMY-16 (Tyr150Ser and Asn346His). Construction of blaCMY-16 mutants confirmed that the substitutions (Tyr150Ser and Asn346His) were primarily responsible for the decreased susceptibility to aztreonam/avibactam. In addition, transfer of blaCMY-16 mutant (Tyr150Ser and Asn346His) plasmid constructs into certain clinical carbapenemase-producing isolates demonstrated >64-fold increased MICs of aztreonam/avibactam and aztreonam/avibactam/ceftazidime. Conclusions Aztreonam in combination with avibactam showed potent in vitro activity against MBL-producing K. pneumoniae. However, our study suggested the likelihood of aztreonam/avibactam resistance among MBL- and AmpC-co-producing strains and clinical practice should beware of the possibility of the emerging resistance.

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In Vitro Selection of Meropenem Resistance among Ceftazidime-Avibactam-Resistant, Meropenem-Susceptible Klebsiella pneumoniae Isolates with Variant KPC-3 Carbapenemases

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00079-17 ◽

2017 ◽

Vol 61 (5) ◽

Cited By ~ 39

Author(s):

Ryan K. Shields ◽

M. Hong Nguyen ◽

Ellen G. Press ◽

Liang Chen ◽

Barry N. Kreiswirth ◽

...

Keyword(s):

Klebsiella Pneumoniae ◽

In Vitro Selection ◽

Carbapenem Resistance ◽

Wild Type ◽

Content Type ◽

Selection Of ◽

New Mutations

ABSTRACT Ceftazidime-avibactam resistance is mediated by bla KPC-3 mutations, which restore carbapenem susceptibility. We subjected Klebsiella pneumoniae isolates with different bla KPC-3 mutations (n = 5) or wild-type bla KPC-3 (n = 2) to serial passages with meropenem. The meropenem MIC against each isolate increased. Mutations in the ompK36 porin gene evolved in 5 isolates. Among isolates with D179Y substitutions in KPC-3, bla KPC-3 mutations reverted to wild type, were replaced by new mutations, or were retained. Carbapenem treatment of ceftazidime-avibactam-resistant K. pneumoniae infections may select for carbapenem resistance.

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Faculty Opinions recommendation of In vitro selection of a deoxyribozyme that can utilize multiple substrates.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1004319.49956 ◽

2002 ◽

Author(s):

Niles Lehman

Keyword(s):

In Vitro Selection ◽

Multiple Substrates ◽

Selection Of

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Faculty Opinions recommendation of CIS display: In vitro selection of peptides from libraries of protein-DNA complexes.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1017658.206556 ◽

2004 ◽

Author(s):

Sachdev Sidhu

Keyword(s):

In Vitro Selection ◽

Dna Complexes ◽

Selection Of

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The Effects of Shock Vancomycin Concentrations on the Formation of Heteroresistance in Staphylococcus aureus

Antibiotics and Chemotherapy ◽

10.37489/0235-2990-2020-65-9-10-3-7 ◽

2020 ◽

Vol 65 (9-10) ◽

pp. 3-7

Author(s):

V. V. Gostev ◽

Yu. V. Sopova ◽

O. S. Kalinogorskaya ◽

M. E. Velizhanina ◽

I. V. Lazareva ◽

...

Keyword(s):

Staphylococcus Aureus ◽

In Vitro Selection ◽

Methicillin Resistant Staphylococcus Aureus ◽

High Concentration ◽

Short Term ◽

High Concentrations ◽

Selection Of ◽

Selection Of Resistance ◽

Test Cultures

Glycopeptides are the basis of the treatment of infections caused by MRSA (Methicillin-Resistant Staphylococcus aureus). Previously, it was demonstrated that antibiotic tolerant phenotypes are formed during selection of resistance under the influence of high concentrations of antibiotics. The present study uses a similar in vitro selection model with vancomycin. Clinical isolates of MRSA belonging to genetic lines ST8 and ST239, as well as the MSSA (ATCC29213) strain, were included in the experiment. Test isolates were incubated for five hours in a medium with a high concentration of vancomycin (50 μg/ml). Test cultures were grown on the medium without antibiotic for 18 hours after each exposure. A total of ten exposure cycles were performed. Vancomycin was characterized by bacteriostatic action; the proportion of surviving cells after exposure was 70–100%. After selection, there was a slight increase in the MIC to vancomycin (MIC 2 μg/ml), teicoplanin (MIC 1.5–3 μg/ml) and daptomycin (MIC 0.25–2 μg/ml). According to the results of PAP analysis, all strains showed an increase in the area under curve depending on the concentration of vancomycin after selection, while a heteroresistant phenotype (with PAP/AUC 0.9) was detected in three isolates. All isolates showed walK mutations (T188S, D235N, E261V, V380I, and G223D). Exposure to short-term shock concentrations of vancomycin promotes the formation of heteroresistance in both MRSA and MSSA. Formation of VISA phenotypes is possible during therapy with vancomycin.

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