OBJECTIVES To explore the cause of third-generation cephalosporin resistance in Australian Acinetobacter baumannii isolates belonging to global clone 1 (GC1). METHODS GC1 isolates from Australia were tested for resistance to ceftazidime and cefotaxime using disc diffusion and MICs. PCR was used to determine the context of ISAba1-ampC configurations and amplicons were sequenced. The level of t...

The incidence of resistance by Enterobacteriaceae to β-lactam/β-lactamase inhibitors combination is increasing in Egypt. Three phenotypic techniques, comprising AmpC disk diffusion and inhibition dependent methods using phenylboronic acid (PBA) and cloxacillin, were compared to PCR based method for detection of plasmid mediated AmpC β-lactamase in common urinary tract isolates. A total of 143 i...

To determine whether the widespread clinical use of -lactams has been selective for Citrobacter freundiiderived alleles of plasmid ampC genes, we generated a Bayesian consensus phylogeny of the published ampC sequences and compared the MICs of 16 -lactam antibiotics for Escherichia coli strains containing cloned copies of the C. freundii ampC alleles. We found that for the majority of compounds...

Resistant bacteria have emerged and established themselves worldwide as a threat to the favourable outcome of common infections in community and hospital settings. Beta lactamase production by several gram negative and gram positive organisms is perhaps the most important single mechanism of resistance to penicillins and cephalosporins. ESBL and AmpC beta lactamases are typically associated wit...

Antibiotic resistance is a growing threat. Fifty non repetitive multi drug resistant gram negative bacterial isolates were screened for ESBL, AmpC, ESBL-AmpC co-production using antibiotic tablets. Of these 56% were Escherichia coli, 16% were Klebsiella spp., 39.6% produced ESBLs, 17.2% AmpC and 13.8% showed co-production. Antibiotic tablets sensitivity for ESBL detection was 93.9% compared to ...

Pseudomonas aeruginosa strains that overexpress mexCD-oprJ become hypersusceptible to imipenem. Disruption of AmpC induction has been suggested to cause this phenotype. However, data from this study demonstrate that hypersusceptibility to imipenem can develop without changes in ampC expression or AmpC activity. Furthermore, hypersusceptibility is not caused by changes in expression of the outer...

In many gram negative bacilli, AmpD plays a key role in both cell well-recycling pathway and β-lactamase regulation, inactivation of the ampD causes the accumulation of 1,6-anhydromuropeptides, and results in the ampC overproduction. In Yersinia enterocolitica, the regulation of ampC expression may also rely on the ampR-ampC system, the role of AmpD in this species is still unknown. In this stu...

The aim of the study was to determine the prevalence of AmpC producing E. coli, Klebsiellapneumoniae and Klebsiellaoxytoca and to evaluate and compare four different phenotypic methods viz; Modified Three Dimensional Test, AmpC Disk Test, AmpC Disk Test with Tris-EDTA and Inhibitor based detection test for the detection of AmpCβ-lactamases in these isolates, collected during a period of 2003 to...

The anterior medial prefrontal cortex (AMPC) in humans is involved in affect and in regulating goal-directed behaviors. The precise function of the AMPC, however, is poorly understood. Using magnetic resonance imaging, we found that bilateral regions in the AMPC were selectively recruited to compute the reliability of subjects' expectations that developed when subjects were learning sequences o...

AmpC β-lactamase is an enzyme commonly produced by Escherichia coli that causes resistance to cephalosporins and penicillins. Enzyme production is controlled by the strength of the promoter encoded by the chromosomal ampC gene, with the level of production affected by the presence of certain mutations in this region. This study sets out to determine the prevalence of ampC promoter mutations pre...