Among 99 clinical Klebsiella pneumoniae isolates resistant to cefoxitin and extended-spectrum cephalosporins, coexistence of AmpC (DHA-1, CMY-2, or CMY-8) and extended-spectrum beta-lactamases (CTX-M and/or SHV) was detected in a total of 35. The remainder produced AmpC (n = 42), extended-spectrum beta-lactamases (n = 9), metallo-beta-lactamases (n = 2), or none of these enzymes (n = 11). Pheno...

Aztreonam was investigated as to its characteristics as a substrate, inhibitor and inducer for the well-defined beta-lactamases of Gram-negative bacteria, and its antibacterial efficacy as to bacterial cells producing eight types of beta-lactamases was also evaluated. Aztreonam was hydrolyzed at measurable rates by class A beta-lactamases, a TEM-2 type penicillinase and the Proteus vulgaris cep...

Multidrug resistance has been increasing among Gram-negative bacteria and is strongly associated with the production of both chromosomal- and plasmid-encoded beta-lactamases, whose number now exceeds 890. Many of the newer enzymes exhibit broad-spectrum hydrolytic activity against most classes of beta-lactams. The most important plasmid-encoded beta-lactamases include (a) AmpC cephalosporinases...

This study was conducted to detect the prevalence of Metallo-Beta-Lactamases (MBLs) and Extended Spectrum Beta-Lactamases (ESBLs) in bacterial isolates from clinical community settings two communities Delta State, Nigeria. Eighty four obtained blood, urine, wound stool patients subjects were analyzed identified by standard microbiological methods. Carbapenemase detection carried out using modif...

INTRODUCTION Production of beta-lactamases is the predominant cause of resistance to beta-lactam antibiotics in Gram-negative bacteria. We investigated the diversity of plasmid-borne beta-lactamase genes and replicon type of the plasmids carrying the respective genes in Gram-negative bacteria recovered from clinical infection in Nigerian hospitals. METHODOLOGY A total of 134 Gram-negative bac...

Staphylococcus aureus produces four types of beta-lactamase (A, B, C, and D). To investigate the effect of specific beta-lactamase type upon staphylococcal resistance, each beta-lactamase was purified to homogeneity, and the Michaelis constants (Km values) and turnover numbers (kcat values) for various penicillin and cephalosporin substrates were determined. Whereas Km values of the four beta-l...

OP0595 is a novel diazabicyclooctane which, like avibactam, inhibits class A and C β-lactamases. In addition, unlike avibactam, it has antibacterial activity, with MICs of 0.5 to 4 μg/ml for most members of the family Enterobacteriaceae, owing to inhibition of PBP2; moreover, it acts synergistically with PBP3-active β-lactams independently of β-lactamase inhibition, via an "enhancer effect." En...

Carbapenemases are a large and diverse family of microbial enzymes that hydrolyze not only carbapenems but also other b-lactams, with the occasional exception of monobactams, such as aztreonam. For clinicians, the nomenclature of carbapenemases, like that of other b-lactamases, is confusing. In keeping with other b-lactamases, carbapenemases can be classified on the basis of function or structu...

β-lactam is the most used antibiotic class in the clinical area and it acts on blocking the bacteria cell wall synthesis, causing cell death. However, some bacteria have evolved resistance to these antibiotics mainly due the production of enzymes known as β-lactamases. Hospital sewage is an important source of dispersion of multidrug-resistant bacteria in rivers and oceans. In this work, we use...

One strategy employed by bacterial strains to resist beta-lactam antibiotics is the expression of metallo-beta-lactamases requiring Zn(2+) for activity. In the last few years, many new zinc beta-lactamases have been described and several pathogens are now known to synthesize members of this class. Metallo-beta-lactamases are especially worrisome due to: (1) their broad activity profiles that en...