Gram-negative bacteria

    Gram-negative bacteria are a diverse group of bacteria that have the same type of cell wall structure. They can share some similarities in their susceptibility and resistance to antibiotics.

    Summary

    Gram-negative bacteria are a diverse group of bacteria that share the same type of cell wall structure, allowing them to be identified and differentiated from gram-positive bacteria using a Gram stain (a lab technique). Following a Gram stain, gram-negative bacteria will appear pink/red under a microscope, while gram-positive bacteria will appear blue/purple.[1]

    The cell walls of gram-negative bacteria consist of a thin peptidoglycan layer — composed primarily of sugars and amino acids — surrounded by an outer lipid membrane that contains lipopolysaccharide (LPS), which can trigger strong immune responses.[1]

    Knowing whether the bacteria causing a given infection are gram-negative or gram-positive is an important initial step for guiding antibiotic choice and predicting pathogenicity. Gram-negative bacteria show greater resistance to some types of antibiotics because of their cell wall characteristics.[2]

    Many different bacterial genera and species are gram-negative. Some examples include Escherichia coli, Helicobacter pylori, Chlamydia trachomatis, Pseudomonas aeruginosa, Klebsiella, and Salmonella.[2]

    References

    1. ^Moyes RB, Reynolds J, Breakwell DPDifferential staining of bacteria: gram stain.Curr Protoc Microbiol.(2009 Nov)
    2. ^Oliveira, J. & Reygaert, W.“Gram-Negative Bacteria”, in StatPearls (Internet). USA: StatPearls Publishing(2023)
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