The world of bacteria is amazingly diverse and very rich. They are found everywhere: in air, soil, on the skin of a person, on his mucous membranes. Under certain circumstances, bacteria become dangerous to humans, causing serious illness. Some of them can be easily treated with antibiotics or even conventional antiseptics, while others are much more difficult to get rid of. Therefore, when making a diagnosis, as well as when prescribing treatment, gram-positive and gram-negative bacteria are isolated. This method of division of microorganisms was proposed in the XIX century, but is still used.
World of bacteria
The kingdom of microorganisms is so diverse and complex that even modern science has not yet fully studied it. There are bacteria that survive at high temperatures and do not die even with prolonged boiling, while others die at the slightest change in temperature or composition of the environment, for example, after adding regular sugar. Some microorganisms feel great in hot springs, in acid, feed on methane or other chemicals.
Bacteria are the oldest organisms and are very widespread in the world. They are found everywhere: at the bottom of the ocean, in the air, in the soil - even at great depths, in the body of living beings. Moreover, science has proved that bacterial cells inside a person are 10 times more than their own. Some microorganisms simply live next to other living things, while others actively interact with them. They can be beneficial or cause various diseases. Moreover, beneficial bacteria are tens of times more than pathogenic.
Many microorganisms are beneficial. For example, those that live in the human intestines participate in digestion and protect it from infections. These are lactobacilli and bifidobacteria. About 40 million species of bacteria live in the human oral cavity, but only 5% of them are pathogenic. There are microorganisms that are involved in the decomposition of waste. But, despite the fact that there are still more beneficial bacteria, their pathogenic species do a lot of harm, as they cause dangerous diseases. Until now, many people around the world are dying of tuberculosis, cholera, tetanus, typhoid fever, botulism and other infections. Therefore, it is very important to learn how to properly interact with the world of bacteria.
Gram Method
Man has long been looking for ways to treat infectious diseases. Once the existence of pathogenic bacteria has been discovered, scientists are trying to classify them in order to figure out how to deal with them. The best method was proposed in 1884 by the doctor Hans Christian Gram. It is quite simple, but informative and is still in use. According to this method, gram-positive and gram-negative bacteria are distinguished.
Dr. Gram used a violet dye when studying microorganisms and noticed that some of them are stainable, while others are not. He found out that this is due to the characteristics of the bacterial cell walls . Since these microorganisms consist of one, less often two cells, it is very important for them to have a strong membrane. Therefore, their cell walls have a complex structure. They protect the internal environment from liquids. The most difficult structure is in gram-negative bacteria. They are resistant to the penetration of saliva, gastric juice and other fluids.
The essence of the Gram method is that the test medium is treated with an aniline dye, fixed with iodine, and then washed with alcohol. At the same time, gram-negative bacteria become discolored, and gram-positive bacteria turn blue. After repeated treatment with red dye, negative species can turn pink, and dead microorganisms become brighter.
Application of the method in medicine
Gram's method for the separation of microorganisms into gram-positive and gram-negative bacteria contributed to the improvement of microbiological studies. It helps to identify the resistance of pathogenic species to drugs, to develop new antibiotics to combat them. After all, the strong cell wall of gram-negative bacteria makes them insensitive to conventional antibacterial drugs. And the membrane of gram-positive microorganisms, although very thick, is permeable to liquids and antibiotics.
Gram-positive and gram-negative bacteria
The Gram method allowed us to divide all microorganisms into two large groups. Their features and characteristics help to choose a more suitable treatment for infectious diseases. Gram-positive bacteria, which quickly turn blue in color with aniline dye, form spores, exotoxins, and therefore are quite hazardous to health. But their shell is permeable to antibacterial drugs.
Like gram-positive, gram-negative bacteria are causative agents of serious diseases. They do not form a spore, and in many cases are conditionally pathogenic. But under certain conditions, endotoxins begin to secrete and are the cause of severe inflammation and intoxication. Due to the complex structure of the cell wall, they are almost insensitive to antibiotics.
The human body contains both types of these microorganisms. The correct ratio of gram-positive and gram-negative bacteria supports the normal microflora of the vagina, intestines, and oral cavity. This helps protect the body against infections.
Gram-positive flora
Most bacteria that can be stained with a purple dye, that is, have a permeable cell wall, are dangerous to humans. These include streptococci, staphylococci, listeria, bacilli, clostridia, mycobacteria, actinomycetes. Staphylococcus aureus is especially dangerous, which affects a weakened body and without treatment quickly leads to the death of the patient. But they also include beneficial lactobacillus lactobacilli.
Gram-positive microorganisms affect the respiratory tract, heart muscle, brain, skin. They provoke a purulent infection in the wounds, blood poisoning.
The diseases they cause
It is gram-positive bacteria that cause such common infectious diseases as:
- tonsillitis, pharyngitis;
- sinusitis, otitis media;
- rheumatism;
- blood poisoning;
- pneumonia;
- inflammation of the brain;
- anthrax;
- foodborne infections;
- botulism;
- diphtheria;
- tetanus;
- gas gangrene.
Gram-negative bacteria
The list is quite large, but among them there are many that do not do any harm to humans. These are mainly conditionally pathogenic microorganisms. Under ordinary conditions, they live in the human body without harming him. The most common are the following gram-negative bacteria. Their types are diverse:
- proteobacteria;
- pseudomonads;
- chlamydia
- meningococci;
- brucella;
- spirochetes;
- gonococci;
- Helicobacter pylori.
Microorganisms that do not stain purple are also resistant to any antibodies and antibacterial drugs. Therefore, the diseases caused by them are very difficult to treat.
What diseases cause
Under certain conditions, gram-negative bacteria cause serious illness. This is due to the fact that the complex membrane of these microorganisms, when destroyed, releases many toxins, which, when carried through the human bloodstream, cause severe intoxication. It turns out that the pathogens are not the bacteria themselves, but the peculiarities of their cell membrane - the lipopolysaccharide layer, which causes the body's immune response. They lead to the development of inflammation. But if a person has immunity in order, he easily copes with such microorganisms, and the infection is not afraid of him.
Gram-negative bacteria include gonorrhea, syphilis, meningitis, and respiratory diseases. Particularly common are bacteria that cause damage to the respiratory and urinary tract, gastrointestinal tract. Gram-negative include such well-known pathogens of infections as Proteus, Escherichia, enterobacteria, Salmonella. They cause salmonellosis, meningitis, typhoid fever, dysentery. In addition, it is such resistant microorganisms that cause severe nosocomial infections. After all, they can survive even after a serious disinfection.
The use of this knowledge in the treatment of diseases
When diagnosing a disease, to determine a more effective treatment, the Gram method is necessarily used to determine which microorganisms caused the disease: gram-positive or gram-negative bacteria. Antibiotics are prescribed depending on this. After all, the wrong treatment can only aggravate the situation.
To determine the pathogen, sputum, discharge from the nose or vagina, analysis of feces, synovial or pleural fluid are examined. These samples are examined by the Gram method.
The most difficult to cure diseases caused by gram-negative bacteria. Basically, they are affected by a combination of two antibiotics or new generation drugs. Effective against them can be Ampicillin or Amoxicillin, Chloramphenicol, Streptomycin, as well as a group of cephalosporins. They can handle the outer membrane of such bacteria.
Knowledge of the structure of the bacterial wall has improved the effectiveness of the treatment of infectious diseases.