Risk Factors of Clonally Related, Multi, and Extensively Drug-Resistant Acinetobacter baumannii in Severely Ill COVID-19 Patients

Table 1

The classes of antibiotics used in this study and their mechanisms of action were obtained from previous studies.

Class of antibiotics	Antibiotics	Mechanism of action	References
Penicillin	Ampicillin, piperacillin, piperacillin-tazobactam, and cefepime	Disrupt the synthesis of the peptidoglycan layer of bacterial cell walls	[34]
Penicillin combinations	Amoxicillin/clavulanate	The second component reduces the effectiveness of some forms of bacterial resistance to the first component	[35]
Cephalosporins	Cefuroxime 2^nd generation, cefoxitin 2^nd generation, cefixime 3^rd generation, ceftazidime 3^rd generation, ceftriaxone 3^rd generation, cefpodoxime 2^nd generation	Disrupt the synthesis of the peptidoglycan layer of bacterial cell walls	[36]
Carbapenems	Imipenem, meropenem	Inhibition of cell wall synthesis	[34]
Aminoglycosides	Amikacin, gentamicin, netilmicin, tobramycin, streptomycin	It inhibits the translocation of the peptidyl-tRNA from the A-site to the P-site, leaving the bacterium unable to synthesize proteins vital to its growth	[37]
Quinolones/fluoroquinolones	Ciprofloxacin, levofloxacin, norfloxacin	Inhibits the bacterial DNA gyrase or the topoisomerase IV enzyme, thereby inhibiting DNA replication and transcription	[34]
Fosfomycin	Fosfomycin	Inactivates enol pyruvyl transferase, thereby blocking cell wall synthesis	[38]
Nitrofurans	Nitrofurantoin	Reduced by bacterial flavoproteins to reactive intermediates that inhibit bacterial ribosomes and other macromolecules	[39]
Sulfonamides	Trimethoprim-sulfamethoxazole	Folate synthesis inhibition	[40]
Monobactams	Aztreonam	Disrupt the synthesis of the peptidoglycan layer of bacterial cell walls	[41]
Tetracyclines	Tetracycline, doxycycline	Inhibits the binding of aminoacyl-tRNA to the mRNA-ribosome complex. They do so mainly by binding to the 30S ribosomal subunit in the mRNA translation complex	[34]
Glycylcycline	Tigecycline	It has a similar structure and action to tetracycline, but it is stronger	[42]
Polymyxin	Colistin	Blocks the peptidoglycan bacterial cell wall outside of the inner membrane	[43]
Lincosamides	Clindamycin	Binds to the 50S subunit of bacterial ribosomal RNA thereby inhibiting protein synthesis	[44]
Macrolides	Clarithromycin, erythromycin	Inhibition of bacterial protein biosynthesis by binding reversibly to the subunit 50S S of the bacterial ribosome, thereby inhibiting translocation of peptidyl-tRNA	[45]