We passaged cells expressing TEM-1 and TEM-12 from a single plasmid through either ampicillin or ceftazidime. We found that the combined effects of recombination and selection removed the bla(TEM-1) allele from the bacterial population when it was passaged through ceftazidime or the bla(TEM-12) allele when cultures were passaged through ampicillin.

Examination of beta-lactam susceptibility of mutants altered in the control of chromosomal beta-lactamase of Pseudomonas aeruginosa supports the view that a constitutive level of beta-lactamase is not an adequate explanation for resistance to cefsulodin and ceftazidime but could be for resistance to piperacillin which has an efficiency of hydrolysis ca. 10 times higher than does cefsulodin or c...

We used meropenem to successfully treat a patient with bacteremia due to ceftazidime-avibactam-resistant, meropenem- susceptible Klebsiella pneumoniae that carried mutant blaKPC-3. Meropenem was bactericidal against ceftazidime-avibactam- resistant K pneumoniae isolates in vitro. Nevertheless, the role of carbapenems in treating such infections remains uncertain, because meropenem resistance is...

In an in vitro pharmacodynamic model, linezolid attenuated the activity of aztreonam and ceftazidime against Escherichia coli. Conversely, synergy was detected at 24 and 48 h when daptomycin or vancomycin was added to aztreonam and ceftazidime. We conclude that significant yet underappreciated interactions may occur between gram-positive-spectrum and gram-negative-spectrum antibacterials.

Avycaz combines an older cephalosporin antibiotic, ceftazidime, and the β-lactamase inhibitor avibactam. Ceftazidime targets penicillin-binding proteins (PBPs) in the bacterial periplasm that are required for cell wall synthesis. Avibactam blocks β-lactamases (β-L) in the periplasm, which would otherwise inactivate the antibiotics resulting in drug resistance.

SCE-2787, a new cephalosporin having a condensed azolium moiety in the 3 position and an aminothiadiazolyl group in the 7 beta side chain, was evaluated for its in vitro and in vivo activities in comparison with those of ceftazidime, flomoxef, cefpirome, and E1040. Against methicillin-susceptible strains of Staphylococcus aureus and Staphylococcus epidermidis, SCE-2787 was more active than ceft...

Antimicrobial susceptibility patterns of Gram negative pathogens (n: 699) isolated from nosocomial infections in Hacettepe University Adult Hospital included in MYSTIC programme between 2000-2004 were determined by Etest (AB BIODISK, Solna, Sweden) using CLSI criteria. Of the total Escherichia coli (n: 179), Klebsiella pneumoniae (n: 168), Pseudomonas aeruginosa (n: 179) and Acinetobacter bauma...

OBJECTIVES The role of sdiA in the acquisition of low-level multidrug resistance (MDR) was analysed and compared with that of marA and soxS in two Escherichia coli clinical isolates and two in vitro-selected mutants. METHODS The mutants were developed by growth in lomefloxacin and ceftazidime. The sdiA, marA, soxS, ftsI, tolC and acrB gene transcript levels were determined by RT-PCR. Analyses...

CTX-M-19 is a recently identified ceftazidime-hydrolyzing extended-spectrum beta-lactamase, which differs from the majority of CTX-M-type beta-lactamases that preferentially hydrolyze cefotaxime but not ceftazidime. To elucidate the mechanism of ceftazidime hydrolysis by CTX-M-19, the beta-lactam MICs of a CTX-M-19 producer, and the kinetic parameters of the enzyme were confirmed. We reconfirme...