Abstract
Along with the recent spread of multidrug-resistant bacteria, outbreaks of extended-spectrum β-lactamase (ESBL) and carbapenemase-producing bacteria present a serious challenge to clinicians. β-lactam antibiotics are the most frequently used antibacterial agents and ESBLs, and carbapenemases confer resistance not only to carbapenem antibiotics but also to penicillin and cephem antibiotics. The mechanism of β-lactam resistance involves an efflux pump, reduced permeability, altered transpeptidases, and inactivation by β-lactamases. Horizontal gene transfer is the most common mechanism associated with the spread of extended-spectrum β-lactam- and carbapenem resistance among pathogenic bacterial species. Along with the increase in antimicrobial resistance, many different types of ESBLs and carbapenemases have emerged with different enzymatic characteristics. For example, carbapenemases are represented across classes A to D of the Ambler classification system. Because bacteria harboring different types of ESBLs and carbapenemases require specific therapeutic strategies, it is essential for clinicians to understand the characteristics of infecting pathogens. In this review, we summarize the current knowledge on carbapenem resistance by ESBLs and carbapenemases, such as class A carbapenemases, class C extended-spectrum AmpC (ESAC), carbapenem-hydrolyzing class D β-lactamases (CHDLs), and class B metallo-β-lactamases, with the aim of aiding critical care clinicians in their therapeutic decision making.
Highlights
Among the recent spread of multidrug-resistant bacteria, outbreaks of extended-spectrum β-lactam- and carbapenemresistant bacteria are a serious problem making treatment difficult and worsening the prognosis of infected patients [1]. β-lactam antibiotics are the most frequently used antibacterial agents, and extendedspectrum β-lactams and carbapenems have been developed as specific drugs to treat bacterial species resistant to penicillins and cephems [2]
Since the 1990s, P. aeruginosa strains have emerged that have acquired resistance to broad-spectrum penicillins, thirdgeneration cephems, carbapenems, anti-P. aeruginosa aminoglycosides, and new quinolones [9, 10]. Among these multidrug-resistant P. aeruginosa (MDRP), one of the major clinical concerns is the spread of P. aeruginosa strains that harbor a carbapenemase because β-lactam antibiotics including carbapenems are the most frequently used antibacterial agents
An anti-methicillin-resistant Staphylococcus aureus (MRSA) drug, albekacin sulfate, a monobactam aztreonam, and polypeptide colistin appear to be effective against MDRP, but the emergence of resistant strains has been reported including extensively drug-resistant P. aeruginosa (XDRP) and pandrug-resistant P. aeruginosa (PDRP) [10, 11]
Summary
Among the recent spread of multidrug-resistant bacteria, outbreaks of extended-spectrum β-lactam- and carbapenemresistant bacteria are a serious problem making treatment difficult and worsening the prognosis of infected patients [1]. β-lactam antibiotics are the most frequently used antibacterial agents, and extendedspectrum β-lactams and carbapenems have been developed as specific drugs to treat bacterial species resistant to penicillins and cephems [2]. TEM-30 and SHV-10, which hydrolyze penicillins and display relative resistance to clavulanic acid, sulbactam, and tazobactam, belong to Bush-Jacoby functional subgroup 2br.
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