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What is the Gram stainThe Gram stain, also known as Gram staining, is a laboratory technique that is used routinely in Microbiological studies of bacteria. It was designed by Christian Gram, a Danish scientist, in the year 1884. Gram aimed to get a proof that it was possible to differentiate between different groups of bacteria to study them and classify them. The test was a success and soon became a very useful technique not only for the study of bacteria, but also to be able to identify them quickly in infection and Select the most appropriate antibiotic to treat it.
The technique is based on applying a series of stains to a sample from any source (sputum, urine, pus, etc.) supposedly containing unidentified bacteria. Dyes stain the wall of purple bacteria, and after a few minutes, is a wash of coloring. After that you can that the dye remains in the bacterial wall or that he has left. In the first case would remain the color purple, and would be Gram positive bacteria, in the second, the wall would have a pink color and would be gram-negative.
These two groups of bacteria are the pillars on which is based the classification of most bacteria expands it. Each of the groups respond differently to each kind of antibiotics, therefore it is a useful technique to select the initial antimicrobial drug before an infection. It must be taken into account that in certain situations (such as sepsis) it is very important to start an adequate early antibiotic treatment, why the Gram stain calls urgently on many occasions.
The Gram stain also has certain limitations. Some bacteria have no wall, as for example the Chlamidias, and may not be identified as viruses. In such cases the stain not color any germ. Another negative aspect of the test is that you can not identify the exact type of bacteria responsible for the infection. So, it is necessary to perform a microbiological culture which is always accompanied by an antibiogram to accurately study the most effective antibiotic.
When a Gram stain is madeA Gram stain is recommended in all situations in which you want to do a first approach to the classification of the isolated bacteria. In addition to her scientific research studies, also is performed in hospitals and clinics around the world to these diseases:
Pneumonia: you can pick up a sample of sputum that a Gram stain is performed to identify organisms responsible for.
Urine infection: the Gram-staining can be used in the urine with suspected infection. The sample should be collected with care not to contaminate it with bacteria of the vagina or the foreskin.
Urethritis: it is the most common sexually transmitted infection and tends to produce secretion through the urethra, which is collected to perform Gram stain.
Meningitis: Gram stain colorized maintained the bacteria that are infecting the cerebrospinal fluid.
Vaginal swab: Although there is multitude of bacteria in the vagina, the Gram stain can dye all of them and see the proportion of Gram positive and Gram negative. Thus the vaginosis, so common in menopausal women are diagnosed.
Abscesses: when accumulates pus anywhere should drain and then plan the antibiotic therapy if it is necessary, and so it is very useful to know which type of bacteria is the cause of the box.
Sepsis: in this case the sample collected is blood; a small tube of each arm.
A Gram stain preparationIf they are going to conduct a study with the Gram stain technique here are the points that you should keep in mind:
Duration: sample collection usually takes very little time, what it takes to be a blood analysis. It usually takes seconds or minutes. Depends on the area where you need to collect the sample (not a urine than a cerebrospinal fluid sample takes the same). Gram stain results take a little longer, usually about an hour.
Admission: admission is never needed. The sample collection is performed at the time. The case that made you the test during an entry to identify the bacteria that causes the infection, but in this case the reason for the income will be your state of health can also be.
Is necessary to be accompanied?: depends on the method of collection of the sample and your state of health. If the test is ordered urgent usually because your state of health is serious and is better you're accompanied.
Drugs: don't need to take any prior medication. It must be said to the doctor all medications you are taking at that time. Some medications can give false negative results of the test, for example if you take antibiotics and want to detect the bacteria causing infection.
Food: you can eat normally, you don't have to go on fasting. But if the sample is blood you can to seize the prick of Analytics to measure yourself with other parameters in blood (sugar, cholesterol, etc.), and you must notify it before so they know that they will be altered.
Clothes: you can wear normal street clothes.
Documents: it is recommended to carry your health card, although most of the times is enough to you to take the wheel with which the doctor sent you proof.
Pregnancy and lactation: this test can be normally in either of the two situations.
Contraindications: there are no contraindications.
Is a Gram stainWhen you get to the consultation the doctor will make you some general questions about your state of health: important diseases, risk factors, lifestyle, symptoms of infection, etc. The doctor will request a Gram stain when it considers it necessary and is the best way to guide your infection antibiotic treatment. Also perform you a general physical examination will assess if you can receive ambulant antibiotic therapy, and it is preferable that you stay logged.
Then conduct you sampling on which will be the Gram stain. According to the site's collection of taking one or other measures are recommended. For example, if urethral should not urinate two hours prior, if it is a best sputum that is first thing in the morning, and if it is better blood that matches a fever peak. But will those details you know the doctor before testing you, so you should not worry.
The Gram stain is performed in the laboratory, and you won't be aware of none of the steps of the technique. So know them summarized them below:
- Extends the sample collected (which tends to be viscous or liquid) on a glass slide, and let it air dry.
- Methanol is applied to the carrier; Thus, bacteria stuck on the surface.
- Gentian violet, a dye that stains all bacteria Purple is added. You should stop for a minute to make effect.
- Washing the colored water sample and add alcohol-acetona to fade the bacteria that are stained with gentian violet. It is the most important part of the test, since if it is left too long all bacteria are desteñirían. After it is washed again with water to eliminate alcohol.
- Add fuchsine, another dye which stains pink bacteria which do not have dyed purple. So you can see under a microscope, although they will be gram-negative.
- The microbiologist studied the sample under a microscope and identifies stained bacteria.
Complications of the Gram stainThe complications of the Gram stain are non-existent. It is a safe test that does not entail risks for persons who are subjected to it. The only risk is to accept false as positive or negative results, and take wrong steps in this regard, as happens when staining are not observed bacteria because an antibiotic has been previously taken. The sample does not usually entail risks, except those of lumbar puncture in the case of meningitis.
Gram stain resultsThe results of the Gram stain take between several minutes and one hour since the sample is collected for study. It is not often that you have to worry about collecting them, since it is usually the doctor who receives the test results (by phone if it is urgent, or with a report if you can wait 24 hours). In consultation, the doctor will be the most appropriate interpretation of the result. If you are admitted shall communicate them yourself during your stay in the hospital, or later if given medical discharge earlier.
The Gram stain is reported with identification or not bacteria. If there are bacteria, the microbiologist will indicate if Gram are positive (purple) or Gram negative (Roses), how have, and are organised. According to their shape they can be cocci (spheres), (thin cylinders) rods or coccobacilli. They can be arranged in cluster or chains; Sometimes they are scattered.
Usually the result of Gram stain can be summarized in bacteria Gram positive or Gram negative bacteria. Only with that is already sufficient to plan the initial antibiotic treatment. Days later will be the results of the microbiological culture, which will get the particular species of bacterium and its sensitivity to antibiotics; You can do the initial antibiotic is changed on the other.
Although it is a test useful may provide false positive and negative. It must keep in mind that the sample is caught in a specific time and is conditioned by the ability of the doctor or nurse that collects it and previous treatments of the patient (especially antibiotics). It must also take into account that the test result depends on the experience of the microbiologist who observes the stained sample.