Classification of bacteria

Gram-positive: bacteria have a cell wall composed of a thick layer of peptidoglycan, teichoic acids and phosphate.

Gram-negative: bacteria have a thin layer of peptidoglycan in the periplasmic space and an outer membrane – lipid bilayer that contains lipopolysaccharides/endotoxin (LPS), lipoproteins and porins.

Gram-negative bacteria of interest to health and their pathologies

Many gram-negative bacteria cause pathologies in humans, and as already explained, they are usually resistant to certain antibiotics. Below are some species of pathogenic gram-negative bacteria and the diseases they cause:

Treponema pallidum – syphilis;

Vibrio cholerae – cholera (of great historical importance);

Chlamydia trachomatis – chlamydiasis;

Neisseria meningitidis – bacterial meningitis;

Neisseria gonorrhoeae – gonorrhea;

Yersinia pestis – bubonic plague, (great historical importance);

Bordetella pertussis – whooping cough;

Salmonella – typhoid fever;

Escherichia coli – intestinal and urinary infections.