Tags

Type your tag names separated by a space and hit enter

Comparative assessment of inoculum effects on the antimicrobial activity of amoxycillin-clavulanate and piperacillin-tazobactam with extended-spectrum beta-lactamase-producing and extended-spectrum beta-lactamase-non-producing Escherichia coli isolates.
Clin Microbiol Infect 2010; 16(2):132-6CM

Abstract

A significant inoculum-size effect has been observed with piperacillin-tazobactam, and has been associated with beta-lactamase production in extended-spectrum beta-lactamase (ESBL) producers. This association has not been previously studied in the case of amoxycillin-clavulanate. Piperacillin-tazobactam and amoxycillin-clavulanate were compared, using high inocula of susceptible strains either harbouring ESBLs or not. Two non-ESBL-producing and 15 amoxycillin-clavulanate-susceptible and piperacillin-tazobactam-susceptible ESBL-producing Escherichia coli isolates, and their respective transconjugants, were tested in dilution susceptibility tests using standard and 100-fold higher inocula. Three ESBL-producing strains and E. coli ATCC 25922 were selected for time-kill studies using standard and high initial inocula. At high inocula, MICs of piperacillin increased >eight-fold for non-ESBL-producing strains, and MICs of piperacillin-tazobactam (8:1 ratio or with tazobactam fixed at 4 mg/L) increased>eight-fold for all ESBL-producing strains. However, amoxycillin MICs were not affected by a high inoculum with non-ESBL-producing strains, whereas the MICs of amoxycillin-clavulanate (2:1 and 4:1) increased <or=four-fold for ESBL producers, using the broth and agar dilution methods. In kinetic studies at a high inoculum, amoxycillin and amoxycillin-clavulanate were bactericidal against E. coli ATCC 25922, whereas piperacillin and piperacillin-tazobactam yielded decreases of <1 log(10) CFU/mL. Similarly, at a high inoculum, only amoxycillin-clavulanate was able to maintain bactericidal rates of killing over 24 h against the ESBL-positive E. coli isolates. The stability of amoxycillin-clavulanate and the contrasting results obtained with piperacillin-tazobactam against high inocula of ESBL-non-producing and ESBL-producing E. coli strains appear to be related to aspects other than the amount of beta-lactamase production.

Authors+Show Affiliations

Department of Microbiology, University Hospital Virgen Macarena, Seville, Spain. llopez@us.esNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19614715

Citation

López-Cerero, L, et al. "Comparative Assessment of Inoculum Effects On the Antimicrobial Activity of Amoxycillin-clavulanate and Piperacillin-tazobactam With Extended-spectrum Beta-lactamase-producing and Extended-spectrum Beta-lactamase-non-producing Escherichia Coli Isolates." Clinical Microbiology and Infection : the Official Publication of the European Society of Clinical Microbiology and Infectious Diseases, vol. 16, no. 2, 2010, pp. 132-6.
López-Cerero L, Picón E, Morillo C, et al. Comparative assessment of inoculum effects on the antimicrobial activity of amoxycillin-clavulanate and piperacillin-tazobactam with extended-spectrum beta-lactamase-producing and extended-spectrum beta-lactamase-non-producing Escherichia coli isolates. Clin Microbiol Infect. 2010;16(2):132-6.
López-Cerero, L., Picón, E., Morillo, C., Hernández, J. R., Docobo, F., Pachón, J., ... Pascual, A. (2010). Comparative assessment of inoculum effects on the antimicrobial activity of amoxycillin-clavulanate and piperacillin-tazobactam with extended-spectrum beta-lactamase-producing and extended-spectrum beta-lactamase-non-producing Escherichia coli isolates. Clinical Microbiology and Infection : the Official Publication of the European Society of Clinical Microbiology and Infectious Diseases, 16(2), pp. 132-6. doi:10.1111/j.1469-0691.2009.02893.x.
López-Cerero L, et al. Comparative Assessment of Inoculum Effects On the Antimicrobial Activity of Amoxycillin-clavulanate and Piperacillin-tazobactam With Extended-spectrum Beta-lactamase-producing and Extended-spectrum Beta-lactamase-non-producing Escherichia Coli Isolates. Clin Microbiol Infect. 2010;16(2):132-6. PubMed PMID: 19614715.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Comparative assessment of inoculum effects on the antimicrobial activity of amoxycillin-clavulanate and piperacillin-tazobactam with extended-spectrum beta-lactamase-producing and extended-spectrum beta-lactamase-non-producing Escherichia coli isolates. AU - López-Cerero,L, AU - Picón,E, AU - Morillo,C, AU - Hernández,J R, AU - Docobo,F, AU - Pachón,J, AU - Rodríguez-Baño,J, AU - Pascual,A, Y1 - 2009/07/15/ PY - 2009/7/21/entrez PY - 2009/7/21/pubmed PY - 2010/3/23/medline SP - 132 EP - 6 JF - Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases JO - Clin. Microbiol. Infect. VL - 16 IS - 2 N2 - A significant inoculum-size effect has been observed with piperacillin-tazobactam, and has been associated with beta-lactamase production in extended-spectrum beta-lactamase (ESBL) producers. This association has not been previously studied in the case of amoxycillin-clavulanate. Piperacillin-tazobactam and amoxycillin-clavulanate were compared, using high inocula of susceptible strains either harbouring ESBLs or not. Two non-ESBL-producing and 15 amoxycillin-clavulanate-susceptible and piperacillin-tazobactam-susceptible ESBL-producing Escherichia coli isolates, and their respective transconjugants, were tested in dilution susceptibility tests using standard and 100-fold higher inocula. Three ESBL-producing strains and E. coli ATCC 25922 were selected for time-kill studies using standard and high initial inocula. At high inocula, MICs of piperacillin increased >eight-fold for non-ESBL-producing strains, and MICs of piperacillin-tazobactam (8:1 ratio or with tazobactam fixed at 4 mg/L) increased>eight-fold for all ESBL-producing strains. However, amoxycillin MICs were not affected by a high inoculum with non-ESBL-producing strains, whereas the MICs of amoxycillin-clavulanate (2:1 and 4:1) increased <or=four-fold for ESBL producers, using the broth and agar dilution methods. In kinetic studies at a high inoculum, amoxycillin and amoxycillin-clavulanate were bactericidal against E. coli ATCC 25922, whereas piperacillin and piperacillin-tazobactam yielded decreases of <1 log(10) CFU/mL. Similarly, at a high inoculum, only amoxycillin-clavulanate was able to maintain bactericidal rates of killing over 24 h against the ESBL-positive E. coli isolates. The stability of amoxycillin-clavulanate and the contrasting results obtained with piperacillin-tazobactam against high inocula of ESBL-non-producing and ESBL-producing E. coli strains appear to be related to aspects other than the amount of beta-lactamase production. SN - 1469-0691 UR - https://www.unboundmedicine.com/medline/citation/19614715/Comparative_assessment_of_inoculum_effects_on_the_antimicrobial_activity_of_amoxycillin_clavulanate_and_piperacillin_tazobactam_with_extended_spectrum_beta_lactamase_producing_and_extended_spectrum_beta_lactamase_non_producing_Escherichia_coli_isolates_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1198-743X(14)61534-2 DB - PRIME DP - Unbound Medicine ER -