Quaternary Ammonium Compounds: An Antimicrobial Mainstay and Platform for Innovation to Address Bacterial Resistance

Abstract

Quaternary ammonium compounds (QACs) have represented one of the most visible and effective classes of disinfectants for nearly a century. With simple preparation, wide structural variety, and versatile incorporation into consumer products, there have been manifold developments and applications of these structures. Generally operating via disruption of one of the most fundamental structures in bacteria-the cell membrane-leading to cell lysis and bacterial death, the QACs were once thought to be impervious to resistance. Developments over the past decades, however, have shown this to be far from the truth. It is now known that a large family of bacterial genes (generally termed qac genes) encode efflux pumps capable of expelling many QAC structures from bacterial cells, leading to a decrease in susceptibility to QACs; methods of regulation of qac transcription are also understood. Importantly, qac genes can be horizontally transferred via plasmids to other bacteria and are often transmitted alongside other antibiotic-resistant genes; this dual threat represents a significant danger to human health. In this review, both QAC development and QAC resistance are documented, and possible strategies for addressing and overcoming QAC-resistant bacteria are discussed.

Antibiotic resistance: What is so special about multidrug-resistant Gram-negative bacteria?

“…When products containing peroxides were used, disinfection was successful (paper presented by Goroncy-Bermes at the RSS Symposium November 2015 [160]). Recent research has indicated that bacterial genes (qac genes) may encode efflux pumps capable of expelling quaternary ammonium compound structures from bacterial cells (MRSA), rendering these compounds less effective [161]. A high prevalence of qacE resistance genes was found among clinical isolates of MDR Acinetobacter baumannii in a Malaysian tertiary care hospital [162].…”

Quaternary ammonium compounds in soil: implications for antibiotic resistance development

“…Recently, a number of 700,000 Mg year -1 for QAC production has been cited by some authors (Tezel and Pavlostathis 2011;Jennings et al 2015). However, in the original reference, this number referred to the amount of estimated annual consumption of cationic surfactants, which comprise both QACs/QAACs, but also include compounds of other substance classes.…”

Scaffold‐Hopping of Multicationic Amphiphiles Yields Three New Classes of Antimicrobials

“…[13] Due to mobile genetic elements, specifically plasmids that are easily sharedi nb iofilms, QAC resistance has become strongly associated with drug-resistant bacteria; recentr eports have estimated that > 50 %o fm ethicillin-resistant Staphylococcus aureus (MRSA) strains show some level of tolerance to QACs. [9] Resistance is thus placing this longstanding line of defense in significant peril.…”