Mechanisms of antibiotic resistance
How Antibiotic Resistance Occurs and Why It Is So Dangerous
What Is Antibiotic Resistance?
In the modern days when new technologies are developing rapidly, the humanity faces the high risk of a biological threat called antibiotic resistance. It occurs when pathogenic bacteria are not affected by antibiotics.
Penicillin was the first antibiotic invented in 1928 by Alexander Fleming. The massive use of it started in the early 1940s, and that was the inception of the major industry of antibiotic production. Soon the scientist warned of the ability of bacteria to become resistant to penicillin. Since this time, lots of new antibiotics have been developed allowing people to treat various simple to serious bacterial infections, but antibiotic resistance can again make people unarmed against such a serious enemy.
It is impossible to get rid of bacteria because they are everywhere, including our bodies that have plenty of bad and good bacteria. Infecting organisms try to survive, and to do this they must be looking for other reservoirs and cause infection there. Bacterial infections are transmitted through indirect or direct contact with the reservoir. Effective antibiotics are exceptionally important for us to survive, and that is why we must do anything possible give pathogens no chance to ruin our health.
How Antibiotic Resistance Occurs
In order to find the right solution for this situation, it is important to understand the mechanisms of antibiotic resistance.
There are four main mechanisms of antimicrobial resistance, including the following:
• Modifying or inactivating the medication (enzymatic destruction); • Changing the target site of the drug by reducing its binding capacity (altered target); • Modifying metabolic pathways to prevent antibacterial effect (enzymatic modification); • Reducing penetration of antibiotic (decreased uptake). Bacteria become resistance to antibiotics in two ways: • Mutating genes; • Acquiring genes from other species or strains.
Acquisition of genes occurs by many mechanisms. There are mobile genetic elements, such as plasmids, transposons, and phages that conduct this transfer. If the antibiotic is used in a small dose, it can initiate such a transfer of genes.
How Different Bacteria Resist to Antibiotics
Beta-lactams are resisted by bacteria in the following ways:
• Enzymatic destruction (staphylococci are resistant to penicillin, and Enterobacteriaceae are resistance to cephalosporins, penicillins, and aztreonam.); • Altered target (staphylococci resist to oxacillin and methicillin); • Decreased uptake (Klebsiella pneumoniae, Enterobacter aerogenes, and Pseudomonas aeruginosa are resistant to imipenem);
The following are beta-lactams that can be resistant to bacteria:
• Aztreonam; • Ampicillin; • Penicillin; • Mezlocillin; • Cefazolin; • Piperacillin; • Cefotaxime; • Ceftazidime; • Imipenem.
Glycopeptides (vancomycin) are deactivated by the altered-target mechanism. For instance, Enterococci are resistant to vancomycin.
Aminoglycosides become ineffective through the following ways:
• Enzymatic modification (lots of Gram-negative bacteria and Gram-positive can resist to aminoglycosides); • Decreased uptake (Gram-negative bacteria are resistant to aminoglycosides); • Altered target (Mycobacterium spp is resistant to streptomycin). The following medications belong to aminoglycosides: • Netilmicin; • Kanamycin; • Gentamicin; • Amikacin; • Tobramycin; • Streptomycin. Quinolones cannot kill bacteria because of the following mechanisms: • Decreased uptake (staphylococci and Gram-negative are resistant to different quinolones); • Altered target (Gram-negative and Gram-positive bacteria are resistant to different quinolones).
It is also important to remember that all of these mechanisms are initiated by the overuse of antibiotics, poor hygiene, and other factors that depend on us. Bacteria are the first things occurred on the Earth, and they will always keep trying to find the way to survive. That is why it is crucial for people to develop new antibiosis and do everything possible to prevent the occurrence of antibiotic resistance.