An Overview Of The Antibiotic Resistance Mechanisms Of Common Gram Positive And Gram Negative Multidrug Resistant Bacteria

Abstract: Antibiotic resistance in multidrug resistant bacteria cause high mortality rates worldwide, where there has been over 1,000,000 deaths reported as of the year 2019. Antibiotics were thought to be the cure for fighting infectious diseases and preventing further spreading of infection. This became a major problem due to bacteria evolving and developing mechanisms for resistance. The purpose of this review was to see if there are differences in the resistance mechanism of gram negative and gram positive bacteria, focusing mainly on the six most common multidrug resistant pathogenic bacteria; Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus faecium, Acinetobacter baumannii, Klebsiella pneumoniae and Streptococcus pneumoniae. The results show that there is a difference in the resistance mechanism between gram positive and gram negative multidrug resistant bacteria. The difference in resistant mechanisms is due to the cell wall compositions of gram negative and gram positive bacteria. The main difference as to why the gram negative bacteria have more resistance is due to the outer membrane. Antibiotics have a hard time to diffuse through and into the cell, that is they can easily decrease their outer membrane permeability. Gram positive bacteria lack an outer membrane which makes them become more susceptible to antibiotics. The most common antibiotic resistance mechanisms in gram negative bacteria are outer membrane mechanisms such as lipid A and lipopolysaccharide modification as well as mutations in porin channels. On the other hand, the most common resistance mechanisms for gram positive bacteria are point mutations especially in penicillin binding proteins as well mutations in the rpoB gene. One important gram positive bacteria is Methicillin resistant Staphylococcus aureus, which developed a new mechanism against antibiotics, a missense mutation and mutation on the promoter region in penicillin binding protein 4. Recently new research has come forward showing that N-chlorotaurine (NCT) inhibits resistance in both gram positive and gram negative multidrug resistant bacteria. The research on NCT is still fairly new and only time will tell if this method of inhibiting resistance will be used in the future. This review highlights the importance and concern of multidrug resistance bacteria, especially due to bacteria being able to rapidly evolve when antibiotics are used incorrectly. It is important to understand the differences in resistance between gram negative and gram positive bacteria and how resistance spreads. This knowledge can be used to develop antibiotics that treat infections. It is however still a challenge to overcome resistance in multidrug resistant bacteria due to evolutionary adaptation especially through horizontal gene transfer, where resistant bacteria can adapt to changing conditions.