antibiotic resistance
Food MicrobiologyBiocide-Tolerant Listeria monocytogenes Isolates from German Food Production Plants Do Not Show Cross-Resistance to Clinically Relevant AntibioticsFoodborne pathogens such as L. monocytogenes can persist in food production environments for a long time, causing perennial outbreaks. Hence, bacterial pathogens are able to survive cleaning and disinfection procedures. Accordingly, they may be repeatedly exposed to sublethal concentrations of disinfectants, which might result in bacterial adaptation to these biocides...
Genetics and Molecular BiologyTyping of mecD Islands in Genetically Diverse Methicillin-Resistant Macrococcus caseolyticus Strains from CattleSince its first description in 2017, the methicillin resistance gene mecD has been detected in M. caseolyticus strains from different cattle sources and countries. Our study provides new insights into the molecular diversity of mecD-carrying M. caseolyticus strains by using two approaches to characterize mecD elements: (i) multiplex PCR for molecular typing of McRImecD and...
Genetics and Molecular BiologyEfflux Pumps in Chromobacterium Species Increase Antibiotic Resistance and Promote Survival in a Coculture Competition ModelAntibiotic efflux pumps are best known for increasing antibiotic resistance of pathogens; however, the role of these pumps in saprophytes is much less well defined. This study describes two predicted efflux pump gene clusters in the Chromobacterium genus, which is comprised of both nonpathogenic saprophytes and species that cause highly fatal human infections. One of the predicted efflux pump clusters is present in every member...
Microbial EcologyCompetition between Escherichia coli Populations with and without Plasmids Carrying a Gene Encoding Extended-Spectrum Beta-Lactamase in the Broiler Chicken GutBacteria that produce extended-spectrum beta-lactamases are resistant to an important class of antimicrobials in human and veterinary medicine. Reduction in antibiotic use is expected to decrease the prevalence of resistance. However, resistance genes often lie on plasmids which can be copied and transferred to other bacteria by conjugation, so in vitro resistance was observed to increase in the absence of antimicrobials. We...
Methods | SpotlightA New Suite of Allelic-Exchange Vectors for the Scarless Modification of Proteobacterial GenomesTargeted modification of bacterial genomes is critical for genetic analysis of microorganisms. Allelic exchange is a technique that relies on homologous recombination to replace native loci with engineered sequences. However, current allelic-exchange vectors often enable only weak selection for successful homologous recombination. We developed a suite of new allelic-exchange vectors, pTOX, which were validated in several medically...
Food MicrobiologyEffects of Sublethal Thymol, Carvacrol, and trans-Cinnamaldehyde Adaptation on Virulence Properties of Escherichia coli O157:H7The present study was conducted to evaluate changes in virulence properties in Escherichia coli O157:H7 adapted to sublethal essential oils (EOs). The results demonstrated reduced motility, biofilm-forming ability, and efflux pump activities in EO-adapted E. coli O157:H7, with no induction of...
Environmental Microbiology | SpotlightLanI-Mediated Lantibiotic Immunity in Bacillus subtilis: Functional AnalysisThe two lantibiotics nisin and subtilin are produced by Lactococcus lactis and Bacillus subtilis, respectively. Both peptides have strong antimicrobial activity against Gram-positive bacteria, and therefore, appropriate protection mechanisms are required for the producing strains. To prevent...
PhysiologyInsights into the Function of the N-Acetyltransferase SatA That Detoxifies Streptothricin in Bacillus subtilis and Bacillus anthracisThis work provides insights into how an abundant antibiotic found in soil is bound to the enzyme that inactivates it. This work identifies residues for the binding of the antibiotic and probes the contributions of substituting side chains for those in the native protein, providing information regarding hydrophobicity, size, and flexibility of the antibiotic binding site.
Genetics and Molecular BiologyExperimental Evolution of Escherichia coli K-12 in the Presence of Proton Motive Force (PMF) Uncoupler Carbonyl Cyanide m-Chlorophenylhydrazone Selects for Mutations Affecting PMF-Driven Drug Efflux PumpsThe genetic responses of bacteria to depletion of proton motive force (PMF), and their effects on drug resistance, are poorly understood. PMF drives export of many antibiotics, but the energy cost may decrease fitness when antibiotics are absent. Our evolution experiment reveals genetic mechanisms of adaptation to the PMF uncoupler CCCP, including selection for increased CCCP efflux but also against the expression of PMF-driven pumps...
Evolutionary and Genomic Microbiology | SpotlightResistance Gene Carriage Predicts Growth of Natural and Clinical Escherichia coli Isolates in the Absence of AntibioticsManaging the spread of antibiotic resistance in bacterial pathogens is a major challenge for global public health. Central to this challenge is understanding whether resistance is linked to impaired bacterial growth in the absence of antibiotics, because this determines whether resistance declines when bacteria are no longer exposed to antibiotics. We studied 92 isolates of the key bacterial pathogen...