Systems Involved in Antimicrobial Resistance and Virulence of Clinically Important Pathogens, 2nd Edition

Dear Colleagues,

The spread of multidrug-resistant (MDR) microbes has caused a public health crisis of global dimensions. MDR bacteria, more specifically carbapenemase-producing Enterobacterales, Pseudomonas aeruginosa and Acinetobacter baumannii, have already been detected all over the globe. The genes encoding carbapenemases are usually associated with mobile genetic elements (MGEs) such as integrons, insertion sequences, transposons and plasmids. Plasmids play an important role in the epidemiology of antibiotic resistance since the acquisition of various resistance genes on a replicon can result in resistance to multiple antibiotics of the host bacterial cell. Additionally, plasmids harbor various genes encoding virulence or adhesion factors, which offer an advantage to the bacterium for successful invasion and survival within the infected host.

Furthermore, bacteria such as A. baumannii and P. aeruginosa show a great propensity to form biofilms on medical devices. It is widely accepted that pathogens within biofilm communities have increased tolerance to extracellular stress. Biofilms are important virulence strategies for A. baumannii, as they provide an insulation that allows bacteria to survive under harsh environmental conditions. Eventually, this favors the acquisition of resistance to multiple antimicrobials, equipping them with multidrug resistance. Additionally, P. aeruginosa is known to produce a variety of cell-associated factors and secrete toxins such as exoenzymes, toxins and secondary metabolites. These factors help the bacterium facilitate successful infection and colonization across a wide range of environments. The synthesis of these factors is regulated by a cell-to-cell signaling mechanism referred to as quorum sensing. Quorum sensing signifies a mode of communication among bacteria to maintain the population density via signal molecules called ‘auto-inducers’. Such cell-to-cell communication has been associated with processes such as bioluminescence, swarming, twitching, antibiotic production, conjugative DNA transfer, sporulation, production of virulence markers, biofilm formation and biosurfactant production.

Finally, many clones of bacterial strains possess a CRISPR/Cas system, which is an adaptive immune system that allows bacteria to limit the entry of genetic elements such as bacteriophages and plasmids. Interestingly, several recent studies have pointed at direct links of CRISPR/Cas systems to the regulation of stress-related phenomena. Thus, exploring the role of those systems in bacterial infections is important for fighting MDR pathogens.

The scope of this Special Issue is to collect original contributions on the systems involved in the antimicrobial resistance and virulence of clinically important pathogens. It is our pleasure to invite you to submit research articles, short communications or review articles related to these topics.

Dr. Costas C. Papagiannitsis
Dr. Ibrahim Bitar
Guest Editors

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• antimicrobial resistance
• mobile elements
• plasmids
• biofilm formation
• virulence
• enterobacterales
• acinetobacter baumannii
• pseudomonas aeruginosa
• quorum-sensing
• CRISPR/Cas system

• Systems Involved in Antimicrobial Resistance and Virulence of Clinically Important Pathogens in Microorganisms (12 articles)