Occurrence of beta-lactamases in bacteria.

Our study highlights the escalating issue of beta-lactam resistance in nosocomial pathogens, driven by the broad spectrum of antibiotic-degrading enzymes and plasmid exchange. We catalogued known beta-lactamases across 230 bacterial genera, identified 2349 potential beta-lactamases across over 673 genera, and anticipate discovering many new types, underscoring the need for targeted gene analysis in combating resistance. This study also elucidates the complex relationship between the diversity and frequency of beta-lactamase genes across bacterial genera, highlighting the need for genus-specific approaches in combating antibiotic resistance and emphasizing these genes' significant global distribution and host-specific prevalence. We report many transcriptional regulators, transposases and other factors in the genomes of 20 different bacterial isolates, some of which are consistent with the ability of these species to adapt to different environments. Although we could not determine precisely which factors regulate the presence of beta-lactamases in specific bacteria, we found that the proportion of regulatory genes, the size of the genome, and other factors are not decisive. Further studies are needed to elucidate key aspects of this process.

Analysis of BlaEC family class C beta-lactamase.

Recent years have witnessed an increased prevalence of intrinsic and acquired beta-lactamase-producing bacteria, severely limiting human and veterinary medicine therapeutic options. The present study aimed to design specific oligonucleotides for rapid PCR detection of the cephalosporinase-encoding gene blaEC (BlaEC family class C beta-lactamase). A total of three primers were designed to detect 2281 variants of the blaEC gene and two sets of primer pairs were also tested against DNA from 11 strains. The study indicates that the proposed primers should be able to detect 100% of all described blaEC genes in different bacterial strains and monitor their spread. After comparing the amino acid sequences, a phylogenetic tree was created based on the presence of conserved amino acids and homologous motifs. More than 24 760 mutations in BlaEC enzymes have been identified. The mutations involving 371 amino acid positions and these hotspots can change the structure and activity of the monitored enzymes. We predicted several BlaEC enzymes with a broadened substrate activity against higher-generation cephalosporins.

Insights into the Resistome and Phylogenomics of a ST195 Multidrug-Resistant Acinetobacter baumannii Clinical Isolate from the Czech Republic.

Increasing antimicrobial resistance in nosocomial pathogens, such as Acinetobacter baumannii, is becoming a serious threat to public health. It is necessary to detect ß-lactamase-producing microorganisms in clinical settings to be able to control the spread of carbapenem resistance. This study was conducted to evaluate the presence of ß-lactamases in a selected clinical isolate of A. baumannii of ST2P/ST195Ox and to characterize possible enzymes, as well as its ß-lactam resistome, using PCR and whole-genome sequencing analysis. PCR and sequencing confirmed that the isolate harbored five bla gene alleles, namely, blaADC-73, blaTEM-1, blaOXA-23, blaOXA-58 and blaOXA-66, as well as aminoglycosides, macrolides, sulfonamides and tetracyclines resistance determinants, which were either chromosomally and/or plasmid located. Furthermore, a gene order comparison using MAUVE alignment showed multiple changes compared with the clinical isolate of Malaysian A. baumannii AC30 genome and 76 regions with high homology. This study suggests that resistance to ß-lactams in this A. baumannii isolate is mainly due to an overproduction of ß-lactamases in combination with other resistance mechanism (efflux pump system).

In Silico Analysis of Extended-Spectrum ß-Lactamases in Bacteria.

The growing bacterial resistance to available ß-lactam antibiotics is a very serious public health problem, especially due to the production of a wide range of ß-lactamases. At present, clinically important bacteria are increasingly acquiring new elements of resistance to carbapenems and polymyxins, including extended-spectrum ß-lactamases (ESBLs), carbapenemases and phosphoethanolamine transferases of the MCR type. These bacterial enzymes limit therapeutic options in human and veterinary medicine. It must be emphasized that there is a real risk of losing the ability to treat serious and life-threatening infections. The present study aimed to design specific oligonucleotides for rapid PCR detection of ESBL-encoding genes and in silico analysis of selected ESBL enzymes. A total of 58 primers were designed to detect 49 types of different ESBL genes. After comparing the amino acid sequences of ESBLs (CTX-M, SHV and TEM), phylogenetic trees were created based on the presence of conserved amino acids and homologous motifs. This study indicates that the proposed primers should be able to specifically detect more than 99.8% of all described ESBL enzymes. The results suggest that the in silico tested primers could be used for PCR to detect the presence of ESBL genes in various bacteria, as well as to monitor their spread.