We tested 190 Klebsiella pneumoniae bloodstream isolates recovered from 189 patients in 30 U.S. hospitals in 23 states to determine the occurrence of extended-spectrum beta-lactamase (ESBL) and AmpC beta-lactamase producers. Based on growth inhibition by clavulanic acid by disk and MIC test methods, 18 (9.5%) of the isolates produced ESBLs. Although the disk diffusion method with standard break...

We read with interest the article by Chopra et al. (1) suggesting that empirical therapy with cefepime for bloodstream infections due to extended-spectrum-lactamase (ESBL)-producing Enterobacteriaceae is associated with excess mortality. The effectiveness of cefepime would be compromised by ESBL production, resulting in higher MICs (2, 3). Several beta-lactamase inhibitors (including clavulanat...

Extended-spectrum beta-lactamases (ESBLs) efficiently hydrolyze extended-spectrum beta-lactams such as cefotaxime, ceftriaxone, ceftazidime, and aztreonam. ESBLs are most often plasmid-mediated. In Taiwan, the prevalence of ESBLs in bacteria has risen, ranging from 8.5 to 29.8% in Klebsiella pneumoniae and 1.5 to 16.7% in Escherichia coli isolates. The most prevalent types of ESBLs are SHV-5, S...

BACKGROUND & OBJECTIVE Detection of AmpC-mediated resistance in Gram-negative organisms poses a problem due to misleading results in phenotypic tests. There are no recommended guidelines for detection of this resistance mechanism and there is a need to address this issue as much as the detection of extended spectrum beta lactamases (ESBLs) since both may co-exist and mask each other. Though res...

Background & Objective: The production of plasmid-mediated AmpC beta-lactamases (PMABLs) among urinary Klebsiella pneumoniae isolates causes a severe problem to the successful treatment of urinary tract infections (UTIs). This study was designed to evaluate antimicrobial resistance, the presence of AmpC beta-lactamase genes, and the genetic relatedness among K. pneumoniae strains separated from...

We conducted a survey in 2015 to evaluate the presence of extended spectrum β-lactamase (ESBL)- and plasmid-mediated AmpC-producing Enterobacteriaceae in retail food and water of the Pearl River in Guangzhou, China, as well as their antibiotic resistance profiles. Samples (88 fresh food samples and 43 water samples) from eight different districts were analyzed by direct plating and after enrich...

Background: Increase in antimicrobial-resistant bacteria continues to be challenge physicians. Particularly, multidrug-resistant (MDR) gram-negative bacilli (GNB), such as extended-spectrum beta-lactamase (ESBL)-producers and carbapenem-resistant pathogens, are becoming a major human health problem globally.Current Concepts: Gram-negative have developed resistance via mechanisms encoding AmpC b...

BACKGROUND AND OBJECTIVES The oprD mutation and AmpC overproduction are the main mechanisms of intrinsic resistance to carbapenems such as imipenem and meropenem in Pseudomonas aeruginosa. MATERIALS AND METHODS In this study, we investigated intrinsic resistance to carbapenems including mutation of oprD and AmpC overproduction in a carbapenem-resistant P. aeruginosa isolated from a burn patie...

In the past 3 decades, classical extended-spectrum beta-lactamases (ESBLs) have probably been the main contributors to gram-negative antimicrobial resistance in Singapore. These appear to be being replaced by the newer CTX-M ESBLs. Metallo-beta-lactamases are found in Pseudomonas aeruginosa but do not seem to have spread widely in Acinetobacter spp. and Enterobacteriaceae. Carbapenem-hydrolysin...