How Gram Stain is Used to Classify Bacteria

Subject: Sciences
Pages: 2
Words: 408
Reading time:
2 min

Gram stain is an important diagnostic feature and correlates with many properties of bacteria. According to their ability to stain with dyes of the trimethylphenol series, all bacteria are divided into two groups: gram-positive and gram-negative. Gram-positive bacteria retain the complex of gentian violet with iodine when the drug is treated with alcohol and turn purple. Gram-negative bacteria do not have this ability and are discolored with alcohol. After further processing with fuchsin or safranin, they acquire a pink color.

Antibiotics are substances that inhibit the growth of living cells, most often prokaryotic and protozoa. The invention of antibiotics can be called a revolution in medicine. The mechanism of antibiotic action mainly consists of their ability to inhibit the growth and destroy cells of bacteria, fungi, and tumors. A large number of bacteria are protected from the outside by a strong framework of complex organic compounds. The destruction of this framework is tantamount to the death of the bacteria. It is this property (destruction of the cell wall) that the antibiotic penicillin and all its derivatives have.

In addition to antibiotics from the penicillin group, cephalosporin and vancomycin have a similar effect. The molecules of these antibiotics block special bacterial enzymes, which act as “stitching” the bacteria’s outer framework. Without this enzyme, bacteria are deprived of the opportunity to grow and die. Antibiotics that block protein synthesis: this group includes tetracyclines, macrolides, aminoglycosides, chloramphenicol, and lincomycin. These antibiotics penetrate bacterial cells and bind to structures that synthesize bacterial proteins and block the bacterial cells’ biochemical processes. A paralyzed bacterium loses the ability to multiply and grow, which is enough to defeat some infections.

Staphylococci are gram-positive aerobic microorganisms, and Staphylococcus aureus is the most pathogenic; it typically causes skin infections, pneumonia, endocarditis, and osteomyelitis. Some strains produce toxins that can cause gastroenteritis, scalded skin syndrome, and toxic shock syndrome. Diagnosis is conducted by cytobacteroscopy of Gram-stained smears and culture. Treatment is usually with penicillinase-resistant beta-lactams, but because resistant strains are often found to these antibiotics, vancomycin and other newer antibiotics may be used. Pathogenic staphylococci are ubiquitous. About 30% of healthy adults, usually temporarily, carry streptococci in the nasal passages and about 20% on the skin; hence, streptococci can infect the carrier itself and other people. S. aureus infection is more common in carriers than in non-carriers and is usually caused by a colonizing strain.