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The family of enzymes carbapenemase – KPC, NDM-1, IMP, VIM, OXA-48 – is undoubtedly one of the most significant health challenges of the century, given the potential for dissemination between species and mortality rates due to infections caused by bacteria with such plasmids. These organisms diffuse their plasmids by conjugation, which gives rise to resistance to almost all existing antibiotics. The laboratory characterization is an essential component when it comes to microorganisms therefore, it is imperative to expose characteristics of Enterobacteriaceae, which are bacilli, non-sporulated, have variable motility, grow in the presence and absence of oxygen, ferment organisms of glucose, are cytochrome oxidase negative, and have the ability to reduce nitrate to nitrite. The general/species that frequently affect humans are Escherichia, Proteus, Enterobacter, Klebsiella, Citrobacter, Yersinia, S higella, and Salmonella, among others. They account for about 80% of gram-negative isolates with a myriad of disease-causing general/species in humans, including urinary tract infections, pneumonia, diarrhea, meningitis, sepsis, endotoxic shock, and many others.
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The response of the immune system depends on both the severity of the infectious process and the structure of the LPS in the aggressive bacteria, which imbricates to the virulence of the BGN and, as a consequence, while some bacteria like Escherichia coli potential induce the immune system, other bacteria like Helicobacter pylori are weakly antigenic.Įnterobacteriaceae are a heterogeneous group widely dispersed in nature.
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The resulting activation of the innate immune response mediated by LPS together with TLR4 receptors culminates in an exacerbated response with the production of cytokines, chemokines, and interferons and its suppression. Thus, LPS can trigger the innate immune response through Toll-like receptors 4 (TLR4), which occurs in many immune cells such as monocytes, macrophages, dendritic cells, and neutrophils. In contrast, there are BGN groups that can trigger such a response in large proportions. However, the LPS is heterogeneous in the various bacterial groups, and some bacteria manifest this antigen weakly due to genetic changes and are not recognized by Toll-like receptors. Lipid A are responsible for the higher endotoxic activity of these bacteria. The external membrane expresses a potent immune response inducer, lipopolysaccharide (LPS), which is composed of three units: a hydrophilic polysaccharide, O antigen, and a hydrophobic domain is known as lipid A. GNB has two membranes, an external and an internal. Some of the mechanisms of resistance include efflux pumps, alteration of the drug binding site and membrane permeability, degradation enzymes, and the conformational change of the drug culminating in its inactivation. These organisms have a range of mechanisms to prevent the action of many antimicrobials used in clinical medicine. Two large groups, Enterobacteriaceae and the non-fermenters, are responsible for most clinical isolates nevertheless, other clinically concerning gram-negative organisms exist, including Neisseria, Haemophilus spp., Helicobacter pylori, and Chlamydia trachomatis.
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These microorganisms have great clinical importance in hospitals because they put patients in the intensive care unit (ICU) at high risk and lead to high morbidity and mortality. Gram-negative bacteria (GNB) are among the most significant public health problems in the world due to the high resistance to antibiotics.