The production of β-lactamases is the most important mechanism of Gram-negative rod resistance to β-lactams. Resistance to ceftazidime and cefepime in clinical isolates of Enterobacteriaceae (especially ESβL-positive E. coli and K. pneumoniae) and P. aeruginosa is life-threatening. However, all strains of the above mentioned species possess chromosomally encoded RND efflux pump systems in addit...

Moraxella catarrhalis is a common pathogen found in children with upper respiratory tract infections and in patients with chronic obstructive pulmonary disease during exacerbations. The bacterial species is often isolated together with Streptococcus pneumoniae and Haemophilus influenzae. Outer membrane vesicles (OMVs) are released by M. catarrhalis and contain phospholipids, adhesins, and immun...

Whole-genome sequencing of penicillin-resistant Staphylococcus arlettae strain SAN1670 from bovine mastitis milk revealed a novel β-lactamase operon consisting of the β-lactamase-encoding gene blaARL, the antirepressor-encoding gene blaR1ARL, and the repressor-encoding gene blaIARL. The functionality of blaARL was demonstrated by gene expression in Staphylococcus aureus. The blaARL operon was c...

Metallo-β-lactamase-producing Pseudomonas aeruginosa (MPPA) is an important nosocomial pathogen that shows resistance to all β-lactam antibiotics except monobactams. There are various types of metallo-β-lactamases (MBLs) in carbapenem-resistant P. aeruginosa including Imipenemase (IMP), Verona integron-encoded metallo-β-lactamase (VIM), Sao Paulo metallo-β-lactamase (SPM), Germany imipenemase (...

Resistance to β-lactam antibiotics is a frequent problem in Pseudomonas aeruginosa lung infection of cystic fibrosis (CF) patients. This resistance is mainly due to the hyperproduction of chromosomally encoded β-lactamase and biofilm formation. The purpose of this study was to investigate the role of β-lactamase in the pharmacokinetics (PK) and pharmacodynamics (PD) of ceftazidime and imipenem ...

AmpC β-lactamase enzymes confer resistance to a wide variety of β-lactam antibiotics, except carbapenems. AmpC β-lactamase-producing bacteria are known to be causative pathogens of nosocomial infections, which are difficult to be treated. Hence, this study was aimed out to determine the prevalence of AmpC β-lactamase enzyme production among Gram-negative bacteria. A total of 500 multidrug-resis...

Indole, which is widespread in microbial communities, has received attention because of its effects on bacterial physiology. Pseudomonas putida and Pseudomonas aeruginosa can acquire ampicillin (Amp) resistance during growth on indole-Amp agar. Transcriptome, mutant, and inhibitor studies have suggested that Amp resistance induced by indole can be attributed to increased gene expression of ttgA...

The panoply of resistance mechanisms in Pseudomonas aeruginosa makes resistance suppression difficult. Defining optimal regimens is critical. Cefepime is a cephalosporin whose 3' side chain provides some stability against AmpC β-lactamases. We examined the activity of cefepime against P. aeruginosa wild-type strain PAO1 and its isogenic AmpC stably derepressed mutant in our hollow-fiber infecti...

Background & Aims: The production of extended-spectrum-β-lactamases (ESBLs) is the main mechanism of resistance to β-lactam antibiotics. The outbreak of isolates simultaneously possessing several resistance mechanisms to β-lactam antibiotics caused a decrease in sensitivity of the confirmatory tests for ESBL. The aim of this study was the evaluation of the β-lactamase disk test method in the de...