What Are Culture And Sensitivity Tests Used For


Antibiotic Sensitivity Test: MedlinePlus Medical Test

Antibiotics are medications that are used to treat bacterial infections. Antibiotics are classified into several categories. Each kind is exclusively effective against a certain bacterial species. In order to determine which antibiotic will be most successful in treating your infection, you need undergo an antibiotic sensitivity test. The test can also be useful in the discovery of antibiotic-resistant illnesses and the development of new treatments. Antibiotic resistance occurs when regular antibiotics become less efficient or completely useless against particular germs in the body.

Antibiotic susceptibility testing, sensitivity testing, and antimicrobial susceptibility testing are all terms used to refer to the same thing.

What is it used for?

The results of an antibiotic sensitivity test are used to determine which antibiotic is the most effective against a bacterial illness. It may also be used to determine which medication will be most effective in treating certain fungal infections.

Why do I need an antibiotic sensitivity test?

If you have an infection that has been demonstrated to be resistant to antibiotics or that is generally difficult to treat, you may require this test to determine antibiotic resistance. Tuberculosis, MRSA, and C. diff. are examples of such diseases. If you have a bacterial or fungal illness that is not responding to normal therapies, you may also require this test.

What happens during an antibiotic sensitivity test?

By obtaining a sample from the contaminated spot, you may do the test. The most often seen sorts of testing are described below.

  • In order to get a blood sample from you, a health care practitioner will insert a tiny needle into a vein in your arm. Following the insertion of the needle, a tiny quantity of blood will be taken and placed in a test tube or vial.
  • It is your responsibility to give a sterile sample of urine in a cup as directed by your health-care practitioner.
  • Your health-care practitioner will collect a sample from the location of your wound using a specific swab
  • This sample will be sent to the laboratory for testing.
  • When you cough up phlegm, you may be requested to use a special cup to collect the liquid, or a special swab may be used to collect the sample from your nose.
  • It is necessary for your health-care professional to put an instrument into your mouth to collect samples from the back of your throat and tonsils
  • This is called a swab biopsy.

Will I need to do anything to prepare for the test?

For an antibiotic sensitivity test, there are no additional preparations that must be made.

Are there any risks to the test?

Having a blood culture test is quite safe and poses very little risk. You may have some little discomfort or bruising at the site where the needle was inserted, but the majority of these side effects will go rapidly. A throat culture carries little danger, however it may cause some pain or gagging in some people. Having a urine, sputum, or wound culture performed poses no danger.

What do the results mean?

The following are the most common ways in which results are described:

  • Susceptible. The treatment that was tested either prevented the development of the bacteria or fungus that was causing your infection or killed it. It is possible that the medication will be an excellent choice for therapy. Intermediate. The medication may be effective at a larger dose
  • Nevertheless, it is resistant. The medication did not prevent the growth of the bacteria or fungus that was causing the infection, nor did it destroy it. A bad choice for therapy is this
  • It is not recommended.

If you have any questions about your results, you should speak with your health-care provider about them.

Is there anything else I need to know about an antibiotic sensitivity test?

Increased antibiotic resistance has been attributed in large part to erroneous antibiotic administration. Make certain that you are using antibiotics correctly by doing the following:

  • An important factor in the growth of antibiotic resistance has been the misuse of antibiotics. Prevent infections from occurring by following these guidelines:

Understand laboratory testing, reference ranges, and how to interpret data in more detail.


  1. ML Bayot and BN Bragg. StatPearls. Treasure Island (Florida) is a tropical paradise. In January 2020, StatPearls Publishing will publish Antimicrobial Susceptibility Testing. The Centers for Disease Control and Prevention (CDC) has further information. Available from: FDA: United States Food and Drug Administration
  2. Atlanta: United States Department of Health and Human Services
  3. About Antibiotic Resistance
  4. Combating Antibiotic Resistance
  5. . Available from: Khan ZA, Siddiqui MF, Park S. Silver Spring (MD): U.S. Department of Health and Human Services
  6. . Methods of Antibiotic Susceptibility Testing: Current and Emerging Technologies Diagnostics are performed (Basel). 3rd of May, 2019
  7. 9(2):49 . Lab Tests Online is a source for this information. The American Association for Clinical Chemistry (AACC) publishes this journal from 2001 until 2020. Laboratory Testing for Antibiotic Susceptibility
  8. Is available from: Lab Tests Online. The American Association for Clinical Chemistry (AACC) publishes this journal from 2001 until 2020. Bacterial Wound Culture is available from the following sources: Lab Tests Online. The American Association for Clinical Chemistry (AACC) publishes this journal from 2001 until 2020. It is possible to order bacteria-specific sputum cultures online from Lab Tests Online. The American Association for Clinical Chemistry (AACC) publishes this journal from 2001 until 2020. This test is available from the following sources: Lab Tests Online. The American Association for Clinical Chemistry (AACC) publishes this journal from 2001 until 2020. Urine Culture
  9. Can be obtained at the Mayo Clinic. The Mayo Foundation for Medical Education and Research was established in 1998 and will continue to operate until 2020. Consumer Health & Safety: The Merck Manual Consumer Version is available from the following sources: Merck Manual Consumer Version. Antibiotics: Are you abusing them? Overview of Antibiotics
  10. . Available from the National Heart, Lung, and Blood Institute. Kenilworth (NJ): MerckCo., Inc., 2020. Overview of Antibiotics
  11. . Department of Health and Human Services, Bethesda, MD. Blood Tests are available through UF Health, the University of Florida’s health care system (UF Health). The University of Florida Health, Gainesville, FL, has published a summary of sensitivity analyses that can be found at:
  12. UW Health. Madison, WI, has published a summary of antibiotic sensitivity tests that can be found at:
  13. UW Health. The University of Wisconsin Hospitals

Sensitivity Analysis

The process of sensitivity analysis, also known as susceptibility testing, assists your doctor in determining the most effective antibiotic to use in the treatment of an infection caused by a microbe. An infection is caused by organisms such as bacteria or fungus that infiltrate your body and produce an infection. Strict sensitivity analysis is a type of test that is used to measure the “sensitivity” of bacteria to an antibacterial agent. It also influences the drug’s capacity to kill germs in the presence of the bacterium.

In order to select the most appropriate antibiotic therapy for an illness and to monitor changes in bacterial resistance to antibiotics, doctors employ antibiograms (sensitivity testing).

A large number of microorganisms are resistant to commonly used antibiotics.

Because of this, the medicine is unable to kill the germs. In order to swiftly evaluate whether or not bacteria are resistant to specific medications, sensitivity analysis is an important tool to have. The following are examples of antibiotic-resistant infections:

  • It is known as susceptibility testing. It is used to assist your doctor in determining the most effective antibiotic to use while treating an infection caused by a pathogen. Infecting microorganisms are organisms such as bacteria or fungus that infiltrate your body and cause an infection to develop there. Strict sensitivity analysis is a type of test that is used to measure the “sensitivity” of bacteria to an antimicrobial. It also has an impact on the drug’s capacity to destroy the germs it encounters. As a result of the test, your doctor will be able to assess which medications are likely to be the most effective in treating your infection. SENSITIVITY TESTING is used by doctors to evaluate the appropriate antibiotic therapy for an illness as well as to monitor changes in bacterial resistance to antibiotics. You need both of these to be successful in your medical treatment. In many cases, standard antibiotics are no longer effective against the bacterium. Thus, the medicine is unable to eliminate the bacterium. In order to swiftly evaluate whether or not bacteria are resistant to specific medications, sensitivity analysis is a valuable approach to employ. Infections that are resistant to antibiotics include those that include:

If your infection does not react to therapy, your doctor may perform a sensitivity analysis for you. This can assist your doctor in determining whether or not the bacterium that is causing your infection has acquired a resistance to antibiotics. This allows your doctor to assess which medication would be the most successful in treating the illness. The first step in sensitivity analysis is to collect a bacterial sample. This sample will be obtained by your doctor by taking a sample from the affected region.

Samples may be obtained from the following sources:

  • Blood, urine, and sputum (spit) were found inside the cervix, as well as a pus-filled wound.

Blood, urine, and sputum (spit); a pus-filled wound inside the cervix; and other signs of infection

  • They are susceptible if the medicine is present and prevents them from growing. As a result, the antibiotic is effective against the microorganisms in question. The term “resistant” refers to the bacteria’s ability to multiply even while the antibiotic is present. This is a symptom of an antibiotic that is ineffective. Intermediatemeans that a greater dose of the antibiotic is required to keep the bacteria from growing

There are very few dangers connected with this test. Blood collection is associated with a modest number of dangers. As an example, you may experience minor discomfort or a little pinching feeling during the blood draw. Following the removal of the needle, you may experience throbbing.Rare dangers associated with collecting a blood sample include:

  • Hematoma (a bruise where blood pools under the skin)
  • Infection (which is typically avoided by cleaning the area before the needle is put)
  • Heavy bleeding (which should be reported to your doctor if it continues for an extended length of time)
  • Numbness or tingling after the procedure.

Your doctor will inform you of any possible dangers related with the sample you have provided. The findings of the antibiotic testing and growth of the bacterial cultures can be analyzed by your doctor after they have been tested with antibiotics. These results might assist you in determining the most effective antibiotic to use to treat your infection.

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Your doctor would most likely pick a medicine from the report that was classified as “susceptible,” which means that it has the ability to combat the bacteria in question.


If there are no known medications available in the susceptible category, you will be prescribed a drug from the “intermediate” group. If you’re taking a medicine from the intermediate category, you’ll almost certainly have to take it in a greater dose and for a longer length of time. You may potentially encounter adverse effects from your medicine.


It is not recommended to take an antibiotic to treat your infection if germs have developed resistance to it. If many antibiotics have been demonstrated to be efficient in eradicating the bacteria that is causing your infection, your doctor will decide which one is the most effective. If a bacteria is “resistant” to all of the antibiotics that are typically used to treat an illness, you may be prescribed a combination of antibiotics. This combination of medications is intended to operate in concert to combat the bacterium.

Additionally, you will most likely be required to take the combination of medications for a lengthy period of time.

Further testing

Some illnesses may need further testing since it is well known that the medications often used to treat the bacteria or fungus that are causing the infection are not always successful in treating the infection. It’s also conceivable that the sample collected from the illness contains more than one bacterium, depending on the circumstances. In order to determine which antibiotic or combination of antibiotics will be most successful in treating the numerous types of bacteria that are causing the infection, susceptibility testing may be performed.

Antibiotics that are effective now may not be effective in six months. When you have an illness caused by bacteria that has developed resistant to various treatments, sensitivity testing are incredibly essential and valuable tools to have.

Culture and Sensitivity Testing

Dana Krempels, Ph.D., of the University of Miami’s Biology Department contributed to this article. The House Rabbit Society of Miami is a non-profit organization dedicated to the welfare of house rabbits. Identifying which medicines will be successful against the specific pathogen (i.e., disease-causing agent) causing the problem is crucial if your bunny is suffering from an infection of any type, from an upper respiratory illness to a jaw abscess to a urinary tract infection. As a result, (1) the bacteria (or other pathogen) must be identified, and (2) the medications that are most efficient at preventing the development of the bacteria (or pathogen) must be discovered.

Bacteria are often recognized in contemporary laboratories using genome characterization, which involves determining the properties of the DNA and RNA of a sample species’ DNA and RNA.

It may, however, be essential to grow the bacteria in order to do a “old-fashioned” culture and susceptibility test if more than identification is required, and if an antibiotic that is generally successful against a particular bacterium strain is ineffective.

An infected tissue sample or discharge from the infected area will be collected by your rabbit-experienced veterinarian, who will send it in a special culture tube to a licensed laboratory for testing (the capsule of an abscess is the best location from which to collect a sample because the internal pus often contains only dead bacteria that will not grow in culture).

As soon as a significant population of bacteria has been established on the plate in the shape of a “lawn,” the technicians will proceed to undertake two major procedures:

  • There are a variety of procedures used to do this, including analysis of lawn features (color, texture, growth pattern, etc.), gram-staining, microscopic inspection, metabolic needs “footprints,” and even DNA sequencing. Bacterial species often isolated from rabbit illnesses include Pasteurella multocida, Pseudomonas aeruginosa, Bordetella bronchiseptica, Staphylococcus aureus, and numerous others
  • But, depending on the location and source of the infection, just about anything might crop up.


  • When bacteria are not present, a clear, circular “halo” (officially known as a “plaque,” or zone of inhibition) will emerge around the antibiotic disk, showing that the disk is not infected with the antibiotic. Because the antibiotic has hindered their growth and/or killed them, this specific antibiotic should be effective against the infection that your rabbit is suffering from. The presence of a hazy plaque shows that not all of the germs in the region surrounding the disk have been eliminated. INTERMEDIATE: In other words, certain individuals of the bacterial population are susceptible to a specific antibiotic, but others are genetically resistant to its effects on the population. Because sensitive individuals of the bacterial population are likely to be killed when an antibiotic with “intermediate” sensitivity is employed, it is expected that only the resistant members will survive, and this will result in the selection of a population resistant to that specific antibiotic. A RESISTANT BACTERIA:In this situation, the filter paper will have no discernible plaque surrounding it, indicating that the bacteria is continuing to grow normally despite the presence of the antibiotic. It is quite likely that an antibiotic that does not produce plaque will be ineffective against the bacteria that is causing your bunny’s sickness.

The bacteria on the Petri dish in the image above (which was shamelessly lifted from the University of Wisconsin at Madison online Textbook of Bacteriology, which provides a more detailed explanation of the appearance of the halos used in bacterial identification) are strongly and moderately inhibited by most antibiotics (which have been impregnated on circles of filter paper), but are unaffected by the antibiotics on the disks located at 5 o’clock and 9 o’clock on the dish.

Your veterinarian will receive the results from the lab within three to seven days of receiving the sample, which will include the bacterium’s species and the spectrum of medications to which the bacteria is susceptible (S), resistant (R), and intermediate (I) in response (I).

Making a decision on which antibiotic to use and how to use it It is important to remember that not all medicines are safe for rabbits!

Make certain that your bunny is examined by a veterinarian who is experienced with the unique medical requirements of rabbits.

The fluoroquinolones (e.g., Baytril and ciprofloxacin), sulfa antibiotics of various types, chloramphenicol, aminoglycoside antibiotics (e.g., gentamycin, tobramycin, amikacin-though these are not recommended as first-line therapy because they can be toxic to the kidneys), and injectible Penicillin-G Procaine are all examples of antibiotics that are generally considered safe for rabbit It is vital that the right rabbit-safe antibiotic for the specific infection be given and provided for a period of time sufficient to allow the bunny’s immune system to overcome the infection (with a little bit of help from the antibiotics).

In certain cases, it may take many weeks on antibiotics (and possibly a combination of two different antibiotics!) to get the disease under control completely.

Don’t put off getting your rabbit properly assessed and treated any longer. If left to its own ways, almost any infection has the potential to evolve into a far more serious issue. It is also critical to maintain high standards.

  • Never skip a dosage
  • Never give less than the recommended dose
  • And to continue the treatment for the whole time period prescribed by your veterinarian, even if the symptoms disappear
  • It is possible to breed resistant strains of bacteria by stopping treatment too soon or giving too low a dose. This is done by killing only the bacteria that are most sensitive to the drug(s) you are using and leaving only the more resistant individuals behind to serve as the progenitors of the next generation and to pass on their genetic resistance tothe sensitive members of the bacterial population. It is not difficult to understand how the abuse of antibiotics might result in serious consequences. What’s the point of a Culture and Sensitivity Test, anyway? There is one word of warning. If a rabbit is found to have “snuffles” or another illness, some veterinarians who are not familiar with rabbits but are familiar with cats and dogs will declare that the condition is caused byPasteruellamultocida after only one examination. It is important not to be misled into believing that a bacterial species such as Pasteurella is the source of a rabies infection unless and until the diagnosis has been verified with a bacterial culture and sensitivity test. It is not only that some strains of Pasteurella are resistant to commonly prescribed antibiotics such as Trimethoprim sulfa, Baytril (enrofloxacin), and even ciprofloxacin, but infections in rabbits can also be caused by even more resistant strains of bacteria, such as Pseudomonas aeruginosa, Bordetellabronchiseptica, Staphylococcus aureus, and others. A culture and sensitivity test to positively identify the pathogen would not only delay your rabbit’s return to good health, but you will also be wasting your money by treating him with an antibiotic that is ineffective against the specific strain of bacteria that he is infected with. If no bacteria grow at all, it’s conceivable that the rabbit has a fungal infection, which is a fungus that grows on the skin. If this is the case, antibiotics are likely to make the situation worse rather than better. Consequently, if the culture and sensitivity test results for bacteria are negative, it is critical to search for fungal species as a backup measure. The treatment of illnesses caused by fungus necessitates the use of completely different drugs. Follow-up: Getting to the Root of the Problem It’s a good idea to undertake some detective work and look for probable reasons once an illness has been brought under control, especially if the condition is chronic. For example, dental disorders such as molar spurs or molar roots extending into the sinuses can result in runny eyes and nose, as well as jaw abscesses and tooth decay. This is more frequent in older rabbits, but all rabbits should have their molars examined on a regular basis for spurs, which are not only uncomfortable, but also potentially deadly. A tear duct flush can occasionally temporarily alleviate runny eye problems, but it is always advisable to have a comprehensive check for molar problems done, including visual inspection for spurs and even radiography to detect molar root infections, before treating the condition. Your bunny’s greatest chances for a long, healthy, infection-free life include good care, a nutritious diet, a pleasant, tranquil habitat, and your ongoing awareness for issues. In the event that none of these measures prove effective, it’s comforting to know that drugs are available that may be administered safely, appropriately, and always under the guidance of a knowledgeable veterinarian who is familiar with rabbits. Rabbit Health
  • HouseRabbit Society of Miami, FL
  • Return to the main page.

Sensitivity Analysis

When it comes to bacteria, sensitivity analysis is used to establish whether or not an antibiotic is effective against microorganisms (germs) that have been isolated from cultures. Sensitivity analysis may be performed in conjunction with the following:

  • The efficiency of antibiotics against microorganisms (germs) such as bacteria that have been isolated from cultures is determined using sensitivity analysis. The following procedures may be used in conjunction with sensitivity analysis:

Alternative Names

Antibiotic sensitivity testing and antimicrobial susceptibility testing are two terms that are used interchangeably.

How the Test is Performed

After the sample has been obtained from you, it is submitted to a laboratory for analysis. There, the samples are placed in specific containers in order to develop germs from the samples that have been gathered. Different antibiotics are coupled with germ colonies in order to determine how well each antibiotic inhibits the growth of each colony of germs. The effectiveness of each antibiotic against a specific bacterium is determined by this test.

How to Prepare for the Test

It is then transmitted to a laboratory after the sample has been taken from you. A specific container is used to cultivate germs from the samples that have been gathered at this location. In order to determine how effectively each antibiotic works in preventing the growth of each colony, different germ colonies are mixed with different antibiotics. A specific organism is tested to assess the effectiveness of each antibiotic.

How the Test will Feel

After the sample has been obtained from you, it is transported to a laboratory. There, the samples are placed in specific containers in order to develop germs from the samples that were gathered. Different antibiotics are coupled with germ colonies to see how well each antibiotic inhibits the growth of each colony. During the test, it is determined how effective each antibiotic is against a certain pathogen.

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Why the Test is Performed

After the sample has been obtained from you, it is submitted to a laboratory for testing. There, the samples are placed in appropriate containers in order to cultivate the germs that were obtained from the samples. Different antibiotics are coupled with germ colonies to see how well each antibiotic inhibits the growth of each colony. The test determines how effective each antibiotic is against a certain bacterium.

What Abnormal Results Mean

If the organism demonstrates resistance to the antibiotics employed in the test, the medications will be ineffective in treating the infection.


The technique utilized to collect the particular culture has an impact on the risks.


A. Charnot-Katsikas and K.G. Beavis. Antimicrobial agents are tested in vitro in order to determine their effectiveness. The authors, McPherson R.A. and Pincus M.R., edited the book Henry’s Clinical Diagnosis and Management by Laboratory Methods (Henry’s). Elsevier, St. Louis, MO, 2017:chap 59 of the 23rd edition.

Culture and Sensitivity

The authors (Charnot-Katskas A and Beavis KG) thank you for your assistance. Antimicrobial drugs are tested in vitro in this procedure. Henry’s Clinical Diagnosis and Management by Laboratory Methods, edited by McPherson RA and Pincus MR. 17th edition, Elsevier Science Publishers, St. Louis, MO; chapter 59


In microbiology, the terms culture and sensitivity refer to laboratory techniques that allow a disease-causing microorganism to be identified and that determine which antibiotics are sensitive to (effective against) the identified microorganism. Culture and sensitivity are two terms that are used to refer to two different types of laboratory techniques. Doctors must take into consideration a plethora of critical criteria while determining the most appropriate treatment for an infectious disease.

If antibiotic treatment of the disease is appropriate, as is the case in the case of bacterial, certain fungal, and some other microbial diseases, the type of antibiotics used may be determined by factors such as ease of absorption, metabolism, ability to reach the infection site, and other factors, among other things.

It is possible that the availability of such information from laboratory testing will save lives in the future. However, over dependence on testing may arise when a simpler, wider approach to therapy may be more economical.

History and Scientific Foundations

Robert Koch, Paul Erlich, and Hans Christian Gram were among the scientists who pioneered the development of microbe culture techniques in the mid- to late 1800s. Louis Pasteur (1822–1895), a French physician and scientist, used some of these techniques to lay the groundwork for the contemporary science of infectious illness at the time. Robert Koch, a German physician who lived from 1843 to 1910, devised a technique for distinguishing distinct types of bacteria and growing pure cultures of specific bacterial types, so laying the groundwork for the science of bacteriology to be known today.

  • Every case of an infectious disease must have the presence of the disease’s agent
  • Otherwise, the disease cannot be treated. It is necessary to separate the agent from the host and cultivate it in vitro (pure culture) for several generations before using it. In order for the illness to be replicated, the agent must be injected into a healthy susceptible host with a pure culture of it. After the experimentally infected host has been recovered, the same agent must be retrieved again.

Gelatin was used by Koch to create a solid medium for bacterial growth, which was later modified by other scientists to incorporate a seaweed known as agar in order to maintain the media’s solid state at room temperature. The German bacteriologist Richard Julius Petri (1852–1921) devised a glass dish that is still in use today and which aids in the promotion of optimal bacterial development. Additionally, in 1877, Koch invented a procedure for dryfixing thin films of bacterial culture on glass slides, dyeing them with aniline dyes, and capturing the microscopic pictures on film, which he published in the journal Science.

The optimum medium for different kinds of bacteria vary, and the identification of a specific infection might still be a question of clinical expertise and judgment.

It was necessary for these staining procedures to rely on two characteristics of the stain: its chromogenicity (the presence of groups of atoms that produce color) and its capacity to dissolve into positively charged ions (cations) and negatively charged ions (anion) (anions).

Anionic dyes, such as eosin, interact with the cationic sections of the bacterial protein being identified, whereas cationic dyes interact with the anionic regions of the bacterial protein being identified.


ANTIBIOTIC RESISTANCE: The capacity of microorganisms to withstand the effects of antibiotic medications is defined as follows: ANTIBIOTIC SENSITIVITY: Antibiotic sensitivity is a term that relates to a bacterium’s susceptibility to an antibiotic. Bacteria can be destroyed by certain antibiotics but not by others, depending on the type of antibiotic used. A wide range of antibiotic sensitivity patterns may be seen in different kinds of bacteria. Broad-spectrum anti-biotics are medications that kill a wide range of bacteria rather than simply those belonging to a certain family, as opposed to narrow-spectrum anti-biotics.

  1. COHORTING: Cohorting is the technique of putting people together who have similar diseases or symptoms in order to lessen the risk of spreading the infection to others.
  2. CULTURE AND SENSITIVITY: As an example, while dealing with germs, this strategy allows for the selection of drugs that will be the most successful in combating the illness.
  3. When Gram’s technique of staining is used, Gram-positive bacteria are any forms of bacteria that have been found and classed as a group that retains crystalviolet dye.
  4. The term “outpatient” refers to a person who obtains health-care services without being admitted to a hospital or clinic for an overnight hospital stay.
  5. The presence of growth is indicated by clouding of the food supply.
  6. SEPSIS:Sepsis is a medical term that refers to a bacterial infection that has spread throughout the body.
  7. Sepsis is sometimes referred to as bacteremia in some circles.

Acute respiratory distress syndrome (ARDS) affects around 750,000 people in the United States each year, according to the Society of Critical Care Medicine.

The incidence rate of sepsis grew by more than 91 percent over the decade of the 1990s.

To use this procedure, bacteria are first dyed with gentian violet dye, followed by washing the pigmented bacteria with iodine solution, then with ethyl alcohol.

Last but not least, we need to stain the Gram-negative bacteria using a reddish-pink dye that is not toxic to the Gram-positive bacteria.

The presence or absence of a Gram-positive or Gram-negative bacterium is frequently an indicative of whether or not the bacteria can be eliminated by a certain antibiotic.

In addition to polysaccharides, proteins, and phospholipids on the surface of their cell walls, Gram-negative bacteria have an additional layer of peptidoglycan that prevents many antibiotics from accessing the cell wall.

Penicillin, for example, functions by attacking the cell wall, but it is stopped from doing so by this additional layer, resulting in the bacteria becoming penicillin-resistant as a result.

Antimicrobial Susceptibility Testing

The Kirby-Bauer disc diffusion susceptibility test, the macrotube dilution susceptibility test, and the microtube dilution test are all susceptibility tests that are used in clinical labs. Kirby-Bauer tests are performed by placing antibiotic disks over an agar plate that has been infected with the organism under investigation. At the concentrations employed in clinical trials, the extent of the zone of inhibition reveals whether or not an organism is susceptible or resistant to an antibiotic (doses).

  1. The least inhibitory concentration (MIC) is the lowest concentration of an antibiotic (in micrograms per milliliter of solution) that will inhibit bacterial growth in vitro, and it is inversely proportional to the concentration of the antibiotic that can be achieved in blood.
  2. This is a time-consuming operation.
  3. It is added to the card by the laboratory, and the organism is automatically spread across all of the wells.
  4. The antibiotics are divided into two categories: those for Gram-positive organisms and those for Gram-negative organisms.


The findings of MIC testing may lead to a modification in the dosage of an antibiotic to be used in therapy or the selection of a different antibiotic to treat the illness. For example, a blood-borneEscherichia coliinfection tested with ampicillin may have a minimal inhibitory concentration (MIC) of 2 mcg/ml (sensitive), which when multiplied by 2–4 times results in a potential peak level of the antibiotic in the blood of 4–8 mcg/l, which is significantly less than an intravenous representative dose from the patient of 47 mcg/mg.

With regard to the leg wound example, a higher MIC of 16 micrograms per milliliter would be associated with a peak blood concentration of 32–64 micrograms per milliliter, which might be above the range of a typical intravenous dosage of bacteria from the patient of 47 micrograms per milliliter.

In this situation, the doctor might consider increasing the ampicillin dose or using a different antibiotic to treat the patient.

Impacts and Issues

A physician’s decision to adjust the dosage of an antibiotic used in therapy, or pick a different antibiotic to treat an illness, depends on the findings of a MIC test performed. If a blood-borneEscherichia coli infection is tested with ampicillin, the MIC may be 2 mcg/ml (sensitive), which when multiplied by 2–4 times results in a potential peak level of the antibiotic of 4–8 mcg/ml in the blood, which is significantly less than an intravenous representative dose from the patient of 47 mcg/mg.

With regard to the leg wound example, a higher MIC of 16 micrograms per milliliter would be associated with a peak blood concentration of 32–64 micrograms per milliliter, which would be above the range of a typical intravenous dosage of bacteria from the patient of 47 micrograms per milliliter.

This would prompt the doctor to consider increasing the ampicillin dose or using a different antibiotic to treat the patient in this situation.


Robert Koch was a pioneer in the study of bacteria, developing concepts and procedures that were later used to the discovery of the particular agents that cause TB, cholera, and anthrax. As a pioneer in microbiology and public health, Koch contributed to the passage of laws and the transformation of prevalent attitudes about cleanliness in order to avoid the spread of infectious illnesses. Koch was given the Nobel Prize in medicine in 1905 for his research on TB. Koch outlined his career purpose in the first article he authored on tuberculosis: “I have begun my research in the interests of public health, and I hope that the greatest possible advantages will accrue as a result of my efforts.” When it comes to treating older persons, the timing and selection of antibiotics might be critical.

This is because deaths and prolonged hospitalizations are reduced if the initial antibiotic treatment attacks and reduces the infecting agent.

The use of antibiotics in long-term care, on the other hand, may be inappropriate in up to 75% of cases; thus, strong minimum criteria for commencing antibiotic therapy should be established.

Overuse of fluoroquinolones has resulted in an increase in fluoroquinolone resistance in specific geographical areas as a result of this.

Newer fluoroquinolones that are active against S. pneumoniae should be kept in reserve, while other antibiotics, such as an advanced generation cephalosporin (e.g., cefotaxime), should be used as the first line of treatment.


As a result of the medical concerns and rising health-care expenditures connected with antibiotic resistance, a special interagency task group was established, which was entrusted with formulating effective methods to tackle the problem. The Interagency Task Force on Antimicrobial Resistance was established in 1999 and is co-chaired by the Centers for Disease Control and Prevention (CDC), the Food and Drug Administration (FDA), and the National Institutes of Health (NIH). It also includes the Agency for Healthcare Research and Quality (AHRQ), the Centers forMedicare and Medicaid Services (CMS, formerly the Health Care Financing Administration), the Department of Agriculture (USDA), the Department of Defense (DoD), the Department of Agriculture ( (HRSA).

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A good example of a vicious circle is the overreliance on specialized antibiotics that have demonstrated in vitro (in the body) potency against specific infections when treatment with broad-spectrum antibiotics would provide faster treatment while not increasing resistance to the specialized antibiotics is shown in this example.

Antibacterial Drugs; Bacterial Disease; Resistant Organisms; Vancomycin-resistant Enterococci are some of the other terms you could come across.


Books Kenneth J. Ryan and C. George Ray are co-authors of this work. Sherris Medical Microbiology: An Introduction to Infectious Disease is a textbook written by Dr. Sherris. McGraw-Hill Medical Publishers, New York, 2003. Sites on the Internet The National Center for Biotechnology Information (NCBI) is a federally funded research and development organization. In Medical Microbiology, 4th ed., Samuel Baron, ed. (April 2, 2007), the chapter “Microbiologic Examination” is included. Health Systems at the University of Virginia.

Kenneth T.

Urine Culture And Sensitivity Test – About, Preparation, Test Results & More

In order to cultivate and identify organisms that may cause a urinary tract infection, a urine culture test is conducted. The organisms that are grown and identified are primarily bacteria and fungi (UTI). In most cases, urine is sterile and devoid of any organisms while it is stored in the bladder. Compared to adult males, ladies and children are more likely than adults to have urinary tract infections. It is possible to pick an appropriate antibiotic by performing an antibiotic sensitivity or susceptibility test against certain types of bacteria or fungus that are the source of any ailment.

This test is necessary because some types of bacteria or fungi are resistant to specific antibiotics and infections, and they will not be cured by therapy with those drugs or infections.

what is urine culture test?

A Urine Culture test is a simple test that is performed to determine whether or not there are any sorts of bacteria present in the urine that might cause infection. However, although urine does not include any germs, microbes, or bacteria in itself, it is the bacterium that enters the Urethra from the Urinary Tract that causes the illness that is known as UTI, or Urinary Tract Infection. The purpose of a urine culture test is to determine whether or not there are any fungus or bacteria in the urinary system and to offer suggestions for drugs that may be used to inhibit the growth of these organisms on an urgent basis.

why do i need urine culture test?

This test is performed to determine whether or not there are any sorts of bacteria present in the Urine that might cause an infection to develop. However, while urine does not include any germs, microbes, or bacteria in itself, it is the bacterium that enters the Urethra from the Urinary Tract that causes the illness that is known as UTI, or Urinary Tract Infection. A urine culture test’s goal is to determine whether or not there are any fungus or bacteria in the urinary system and to recommend drugs that may be used to stop the growth of these organisms on an urgent basis.

reason to take urine culture and sensitivity test

You are required to get this examination due to the symptoms listed below. The following are the general signs and symptoms of a Urinary Tract Infection:-

  • Urination that is painful or difficult, with a burning feeling
  • Increased frequency of urination
  • Urine that smells foul, seems hazy, or is reddish in appearance
  • Lower abdominal (belly) pain and pressure, as well as lower back pain I’m getting the chills
  • Fever, malaise, and exhaustion without warning

what other tests might i have along with urine culture test?

In the first instance, a doctor would not request a report on a Urine Culture straight from the laboratory. In the event that a patient presents to a doctor complaining of urinary sensitivity issues, the doctor will likely order a Urine Routine test to rule out any underlying causes. A urine routine test is a collection of tests that are performed on a urine sample to determine whether or not a medical problem or disease is present. That is the first stage, and it will inform you that there is a problem; however, the Urine Culture report will show you exactly what the problem is, and it will also get you closer to finding a solution.

what do my test results mean?

A “Positive” result on the Urine Culture test indicates that a certain amount of bacteria or organisms have been discovered in the Urine Sample and that the infection is almost probably caused by these germs. The Culture report not only identifies the many types of bacteria that are present, but it also indicates their sensitivity to different antibiotics. As a result, you can tell just by looking at this data which antibiotics would be the most beneficial. The usual range for urine culture colonies per milliliter is between 10,000 to 1,00,000 colonies per milliliter, but if it rises over 1,00,000 colonies per milliliter, it indicates that Urine Infection is widespread and that remedial measures must be implemented.

how is urine culture test done?

In order to perform the Urine Culture and Sensitivity test, the Urine Sample must be collected in a clean sterilized hygienic bottle, ideally with an empty stomach in the early hours of the morning. First and foremost, the results of the Urine Routine test are announced 14-16 hours after the test was performed. After receiving the Urine Culture report, one must wait between 48 and 72 hours for the results to be released. An employee of the laboratory will maintain a careful eye on the Urine Sample while it is held in the laboratory for 2-3 days.

In the event that no germs are detected in the urine sample, the test is regarded as negative.

The bacteria E-Coli are the most frequent bacteria that cause urinary tract infections.

Following the discovery of the bacteria, they would do additional testing to determine the results of the urine sensitivity test, which would include identifying antibiotics that would be effective in this case and totally treat the illness.

does urine culture test pose any risk?

No, the Urine Culture and Sensitivity Test does not pose any danger to the patient. It just serves to assist us in getting to the base of the problem and solving it.

what might affect my test results?

When collecting the Urine Sample, extreme caution must be exercised to ensure that the urine does not come into touch with the human skin, hands, or any other source that might dilute the test totally, since this could result in a false positive. Even if the container in which the sample is taken is not sterilised or clean, it has the potential to utterly derail the report’s outcome.

sample required?

Specimens of the following types: urine, Procedure for collecting specimens: Urine should be collected in the middle of the stream (not at the beginning or at the finish). Before collecting the genitals, take special care to clean them thoroughly. To obtain a sample, follow the steps outlined below:

  • The first few drops of pee, or the initial few drops of urine, should be flushed down the toilet. To collect a mid-stream urine sample, place it in the sterile container supplied. It is not recommended to collect the last section of the urine or the finish of the urine stream. Cover the container with a lid. During the collecting time, store it in the refrigerator or another cold location.

There is no need for any prior preparation. For at least one hour before the test, refrain from urinating, and drink a glass of water 15-20 minutes before sample collection.

how do i prepare for urine culture test?

For the Urine test, there is no need to do any particular preparation. All you have to do is make sure that you have an empty stomach and that you are well hydrated. Ensure that you drink at least 3-4 glasses of water 10 minutes before the exam. It is critical to ensure that the urine sample obtained is from mid-stream and not at the beginning or finish of the treatment in order to obtain accurate findings.

portea at-home urine culture and sensitivity test in top location include:

Bangalore, Delhi-NCR, Chennai, Hyderabad, Kolkata, Pune, Lucknow, and Indore are some of the cities in India.

Understanding results of Urine culture and sensitivity

Reference Range Interpretation
100,000 colonies/ml Positive
10,000-100,000 colonies/ml Indeterminate
10,000 colonies/ml Negative

Inference: Urine is typically free of pathogens. However, it is possible that some contamination from skin germs will occur during the collection of the urine. So up to 10,000 colonies of bacteria per milliliter of liquid are deemed typical. A positive urinary tract infection is defined as having more than 100,000 colonies per milliliter of urine. The culture is uncertain for numbers ranging between 10,000 and 100,000 individuals. ‘* A reference range is a collection of numbers that assists a healthcare worker in interpreting the results of a medical test.

Reference ranges may also differ between laboratories in terms of valueunits, depending on the equipment used and the methodology employed to determine the reference ranges.


When there is an observation of painful pee output, a urine culture and sensitivity test is performed. This test is performed in order to discover any micro-organisms present in the body and to remove them if present.

Culture and Sensitivity

An animal illness culture and susceptibility test is the most accurate technique to identify the bacteria that are causing the disease and to help guide the selection of the most appropriate antibiotic. In many circumstances, the doctor may need to make a decision on which antibiotic to administer before culture and susceptibility data are available. When selecting an antibiotic, the doctor considers the likelihood of effectiveness against the organisms most usually recognized as pathogens of the body location in question, as well as the patient’s overall health.

It has been estimated that antibiotic medication should be modified roughly 40 percent of the time upon receipt of susceptibility testing findings, according to the literature.

Failure to adhere to this concept contributes to the development of antibiotic resistance and the failure of therapeutic interventions.

Antimicrobial Susceptibility and Isolates

The antimicrobial susceptibility testing is carried out on isolates that, after taking into account the body location and illness status, are suspected of playing a role in the disease process. In contrast, testing isolates that are frequent pollutants or members of the natural flora would not give helpful information and might lead to incorrect antibiotic treatment. In the event of a specific case, you are always welcome to contact the lab and request extra tests. It is possible that extra testing will incur an additional fee.

Interpreting Susceptibility Results

FIGURE 1: Plates with antibacterial dilutions in the proper concentrations. Antimicrobial susceptibility testing of bacterial isolates is performed by the Bacteriology Section using a wide range of antimicrobial drugs. We employ antimicrobial susceptibility testing panels (see Antimicrobial Susceptibility Testing Resources) that are routinely tested for antibiotic resistance depending on the bacterial species, the animal source of the isolate, and, in certain circumstances, the body region that is being tested for.

In addition to our standard panels, we can test for sensitivity to a variety of additional medications upon request, as well as for microorganisms that are very resistant to antibiotics.

In order to test an organism’s sensitivity to different antibiotics, there are two basic approaches that are employed.

1) is our favorite and most often used method of assessing antimicrobial susceptibility since it offers quantifiable data in the form of a Minimum Inhibitory Concentration (MIC) (MIC).

As a consequence, the MIC and a qualitative result of Sensitive, Intermediate, or Resistant are supplied for results obtained using this approach.

Zones of bacterial growth inhibition surrounding antimicrobial disks are depicted in Fig.

(Agar containing blood MH).

In this procedure, the bacteria of interest are grown on a solid agar plate, after which antibiotic-impregnated disks are dropped onto the surface of the plate.

2). It is then determined if the zone is sensitive, intermediate, or resistant based on the zone size. As a result, results obtained through this approach are only offered as a qualitative result of S, I, or R.

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