12/24/2023 0 Comments Gram negative bacteria listThis difference is due to the composition or the morphology of the cell wall in each bacterial type. Gram- positive bacteria stained violet or purple and Gram-negative bacteria don’t retain the complex stain and counter stain with safranin to give a pink color. In 1884 Hans Christian Gram developed a method to distinguish between Gram-positive and Gram-negative bacteria by using a crystal violet-iodine complex and a safranin counter stain. In 2017, the WHO published a list of bacteria where new antibiotics to tackle them are needed urgently and grouped them according to their priority as critical, high, and medium ( Figure 1). Resistance to antimicrobials is a growing crisis in clinical medicine. Furthermore, genetic changes in the DNA which can alter the production of protein leading to different components and receptors that cannot be recognized by the antibiotic, and finally DNA transfer through a horizontal gene transfer between bacteria via transformation or transduction or by conjugation. The mechanisms of antibiotic resistance are categorized into four groups: intrinsic resistance in which bacteria can change their structures or components, another way is acquired resistance, where bacteria can acquire new resistance genes and DNA from other resistant bacteria. Antibiotic resistance evolves when the bacteria can escape the effect of antibiotics by different mechanisms, like neutralizing the antibiotics, pumping them outside of the cell, or modifying their outer structure resulting in inhibition of the drugs’ attachment to the bacteria. The global effort to develop new antibiotics or modify existing ones to fight resistant pathogens globally is now huge. Unfortunately, most antibiotics are available over the counter in the developing countries and can be dispensed without prescription therefore, patients and general public education are crucially needed. Widespread excessive dispensing and irresponsible use of antibiotics has resulted in the development of resistant strains. Since the discovery of penicillin by Fleming in 1929, a large number of antibacterial agents have been developed and have had a huge impact on human health and the mortality rates of humans around the world. Throughout history, natural products have been utilized to treat a variety of diseases cinchona tree containing quinine to treat malaria, penicillin for the treatment of infectious diseases, and others. Another promising trend was by referring to nature to develop naturally derived agents with antibacterial activity on novel targets, agents such as bacteriophages, DCAP(2-((3-(3,6-dichloro-9 H-carbazol-9-yl)-2-hydroxypropyl)amino)-2(hydroxymethyl)propane1,3-diol, Odilorhabdins (ODLs), peptidic benzimidazoles, quorum sensing (QS) inhibitors, and metal-based antibacterial agents. Research efforts have been made to meet the urgent need for new treatments some have succeeded to yield activity against resistant Gram-negative bacteria by deactivating the mechanism of resistance, like the action of the β-lactamase Inhibitor antibiotic adjuvants. Several strategies have been reported to fight and control resistant Gram-negative bacteria, like the development of antimicrobial auxiliary agents, structural modification of existing antibiotics, and research into and the study of chemical structures with new mechanisms of action and novel targets that resistant bacteria are sensitive to. Due to their distinctive structure, Gram-negative bacteria are more resistant than Gram-positive bacteria, and cause significant morbidity and mortality worldwide. The majority of the WHO list is Gram-negative bacterial pathogens. In 2017, the World Health Organization (WHO) has published a list of antibiotic-resistant priority pathogens, pathogens which present a great threat to humans and to which new antibiotics are urgently needed the list is categorized according to the urgency of need for new antibiotics as critical, high, and medium priority, in order to guide and promote research and development of new antibiotics. Therefore, new antibacterial agents are crucially needed to overcome resistant bacteria. Some bacterial strains have acquired resistance to nearly all antibiotics. Antimicrobial resistance represents an enormous global health crisis and one of the most serious threats humans face today.
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