BACKGROUND NXL104 is a novel-structure beta-lactamase inhibitor with potent activity against both class A and class C enzymes. Among the class A carbapenemases, KPC-type enzymes are now spreading rapidly and KPC-related carbapenemase resistance is an emerging phenomenon of great clinical importance. The activity of NXL104 against KPC beta-lactamases was examined. METHODS Enzymatic activity of...

BACKGROUND Staphylococci release a large number of enzymes. Some of these, such as coagulase, beta- lactamase, hemolysins and biofilms are considered indices of pathogenicity. OBJECTIVES The aim of the current study was based on the isolation and identification of Staphylococcus aureus and coagulase negative Staphylococci (CNS) strains from various skin lesions and examining their biofilms, b...

Two clinical isolates of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae were noted to be less susceptible than expected to imipenem. Both were missing outer membrane proteins that serve as channels for antibiotic entry. The role of beta-lactamase in resistance was investigated by eliminating the original ESBL and introducing plasmids encoding various ESBLs and AmpC beta...

The clinical strain Escherichia coli TO799 was resistant to penicillin-clavulanate combinations and ceftazi-dime and was not reproducibly detected as an extended-spectrum ␤-lactamase (ESBL) according to the standards of the Clinical Laboratory Standards Institute (CLSI; formerly NCCLS) and the national guidelines of the French Society for Microbiology (Comité de l'Antibiogramme de la Société Fr...

background beta-lactam resistance in gram-negative bacteria, especially escherichia coli, is a main clinical problem. it is often caused by the co-production of β-lactamases, particularly extended-spectrum β-lactamases (esbls) and ampc enzymes. it may lead to a problem for diagnosis via recommended phenotypic tests by the clinical and laboratory standards institute (clsi). conversely, β-lactama...

tRNAs are synthesized as precursor RNAs that have to undergo processing steps to become functional. Yeast Trz1 is a key endoribonuclease involved in the 3΄ maturation of tRNAs in all domains of life. It is a member of the β-lactamase family of RNases, characterized by an HxHxDH sequence motif involved in coordination of catalytic Zn-ions. The RNase Z family consists of two subfamilies: the shor...

Ceftazidime-resistant Escherichia coli and Klebsiella pneumoniae (49 and 102 isolates, respectively) were collected from Barnes-Jewish Hospital, St. Louis, Mo., from 1992 to 1996. They were uniformly resistant to ceftazidime, generally resistant to aztreonam, and variably susceptible to cefotaxime. Four representative E. coli strains and 15 Klebsiella strains were examined. From one to four bet...

Production of extended-spectrum beta-lactamase (ESBL) is one of the most important resistance mechanisms that hamper the antimicrobial treatment of infections caused by Enterobacteriaceae. ESBLs are classified into several groups according to their amino-acid sequence homology. While TEM and SHV enzymes were the most common ESBLs in the 1990s, CTX-M enzymes have spread rapidly among Enterobacte...

1. Yigit H, Queenan AM, Anderson GJ et al. Novel carbapenemhydrolyzing b-lactamase, KPC-1, from a carbapenem-resistant strain of Klebsiella pneumoniae. Antimicrob Agents Chemother 2001; 45: 1151–61. 2. Smith Moland E, Hanson ND, Herrera VL et al. Plasmidmediated, carbapenem-hydrolysing b-lactamase, KPC-2, in Klebsiella pneumoniae isolates. J Antimicrob Chemother 2003; 51: 711–4. 3. Yigit H, Que...

Production of beta-lactamases, the enzymes that degrade beta-lactam antibiotics, is the most widespread and threatening mechanism of antibiotic resistance. In the past, extensive research has focused on the structure, function, and ecology of beta-lactamases while limited efforts were placed on the regulatory mechanisms of beta-lactamases. Recently, increasing evidence demonstrate a direct link...