Resistance to the expanded-spectrum cephalosporins has become a worldwide problem. Such resistance occurs primarily in members of the family Enterobacteriaceae via the production of extendedspectrum β-lactamases (ESBLs), which are capable of hydrolyzing the oxyimino-cephalosporins and monobactams (Bush et al., 2001; Pitout et al., 2004). It has recently been shown that the CTX-M β-lactamases ar...

The expression of resistance to cephalosporins is highly varied and due to various mechanisms. The greatest disadvantage of the cephalosporins is that they are inactivated by the array of beta-lactamases produced by bacteria. The high levels of chromosomal enzymes produced by these organisms are a major cause of cephalosporin resistance. Plasmid-mediated beta-lactamases (PMBLs) have also been i...

Objective: In addition to assessing the phenotypic development of biofilms and beta-lactamases, in current study, Pseudomonas aeruginosa isolates from intensive care units (ICU) patients with prevalent drug resistance are being evaluated. Methods: Standard CLSI recommended protocols were utilized detect beta-lactamases such as extended-spectrum β-lactamases (ESBL), metallo beta-lactamase (MBL),...

Emergence of multidrug-resistant strains of Shigella is a growing concern across the globe. Third-generation cephalosporins are used for treating infections caused by multidrug-resistant Shigellae. However, resistance to these cephalosporin antibiotics due to extended-spectrum ß-lactamases, has emerged as a new problem. So far extended-spectrum ß-lactamases producing Shigella has not been repor...

4 Hopkins KL, Kirchner M, Guerra B et al. Multiresistant Salmonella enterica serovar 4,[5],12:i:in Europe: a new pandemic strain? Euro Surveill 2010; 15: 19580. 5 Rodrı́guez I, Barownick W, Helmuth R et al. Extended-spectrum b-lactamases and AmpC b-lactamases in ceftiofur-resistant Salmonella enterica isolates from food and livestock obtained in Germany during 2003–07. J Antimicrob Chemother 200...

A population analysis of 103 multidrug-resistant Pseudomonas aeruginosa isolates from Croatian hospitals was performed. Twelve sequence types (STs) were identified, with a predominance of international clones ST235 (serotype O11 [41%]), ST111 (serotype O12 [15%]), and ST132 (serotype O6 [11%]). Overexpression of the natural AmpC cephalosporinase was common (42%), but only a few ST235 or ST111 i...

A 1536-nucleotide-long sequence that carries the ampC beta-lactamase gene of the Escherichia coli K-12 chromosome has been determined. This gene codes for a protein of 377 amino acids, of which the first 19 amino acids form a signal peptide. The molecular weight of the mature enzyme was determined to be 39,600. The ampC beta-lactamase with a substrate specificity for cephalosporins showed no si...

Background Resistance of Klebsiella pneumoniae to carbapenems is mainly associated with acquired carbapenem-hydrolyzing b-lactamases [1]. These b-lactamases can be metallo b-lactamases (IMP, VIM), expanded-spectrum oxacillinases (OXA-48), or Ambler class A enzymes (NMCA, IMI, SME, GES, and KPC) [1,2]. The most common class A carbapenemases in K. pneumoniae are the K. pneumoniae carbapenemases (...

MOTIVATION Beta-lactamases confer resistance to a broad range of antibiotics and inhibitors by accumulating mutations. The number of beta-lactamases and their variants is steadily increasing. The horizontal gene transfer likely plays a major role in dissemination of these markers to new environments and hosts. Moreover, information about the beta-lactamase classes and their variants was scatter...

Respiratory isolates of Klebsiella pneumoniae in Korea during 2002-2003 were studied to determine the prevalence and types of extended-spectrum beta-lactamases (ESBLs) and plasmid-mediated AmpC beta-lactamases (PABLs). ESBL-production was tested by double-disk synergy, and genotypes of beta-lactamases were determined by PCR and sequencing. ESBLs were detected in 28.4% of 373 isolates, and the m...