Antibiotic Sensitivity Test

Antibiotics are medicines used to fight bacterial infections. Each type of the antibiotics is only effective against certain bacteria. An antibiotic sensitivity test can help find out which antibiotic will be most effective in treating your infection.

The test can also be helpful in finding a treatment for antibiotic-resistant infections. Antibiotic resistance happens when standard antibiotics become less effective or ineffective against certain bacteria. Antibiotic resistance can turn once easily treatable diseases into serious, even life-threatening illnesses.

Other names: antibiotic susceptibility test, sensitivity testing, antimicrobial susceptibility test

What is it used for?

An antibiotic sensitivity test is used to help find the best treatment for a bacterial infection.

Why do I need an antibiotic sensitivity test?

You may need this test if you have an infection that has been shown to have antibiotic resistance or is otherwise hard to treat. These include tuberculosis, MRSA, and C. diff. You may also need this test if you have a bacterial or fungal infection that is not responding to standard treatments.

What happens during an antibiotic sensitivity test?

The test is done by taking a sample from the infected site. The most common types of tests are listed below.

Blood culture

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial.

Urine culture

You will provide a sterile sample of urine in a cup, as instructed by your health care provider.

Wound culture

Your health care provider will use a special swab to collect a sample from the site of your wound.

Sputum culture

You may be asked to cough up sputum into a special cup, or a special swab may be used to take a sample from your nose.

Throat culture

Your health care provider will insert a special swab into your mouth to take a sample from the back of the throat and tonsils.

Are there any risks to the test?

There is very little risk to having a blood culture test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

There is no risk to having a throat culture, but it may cause slight discomfort or gagging.

There is no risk to having a urine, sputum, or wound culture.

What do the results mean?

Results are usually described in one of the following ways:

The tested medicine stopped the growth or killed the bacteria or fungus causing your infection. The medicine may be a good choice for treatment.

The medicine may work at a higher dose.

The medicine did not stop the growth or kill the bacteria or fungus causing the infection. It would not be a good choice for treatment.

If you have questions about your results, talk to your health care provider.

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

Incorrect use of antibiotics has played a big role in the rise in antibiotic resistance. Make sure you use antibiotics the right way by:

Taking all doses as prescribed by your provider

Only taking antibiotics for bacterial infections. They don’t work on viruses, like colds and flu.




Diarrhea is when you pass loose or watery stool.


In some people, diarrhea is mild and goes away in a few days. In other people, it may last longer.

Diarrhea can make you feel weak and dehydrated.

Diarrhea inbabies and children can be serious. It needs to be treated differently than you would treat diarrhea in adults.

Talk with your health care provider if your child has diarrhea. There can be a lot to know. Your provider can help you learn how to recognize and treat diarrhea in babies and in children.

Causes of Diarrhea

The most common cause of diarrhea is the stomach flu (viral gastroenteritis). This mild viral infection most often goes away on its own within a few days.

Eating or drinking food or water that contains certain types of bacteria or parasites can also lead to diarrhea. This problem may be called food poisoning.

Certain medicines may also cause diarrhea, including:

Some antibiotics

Chemotherapy drugs for cancer

Laxatives containing magnesium

Diarrhea may also be caused by medical disorders, such as:

Celiac disease

Inflammatory bowel diseases (Crohn disease and ulcerative colitis)

Irritable bowel syndrome (IBS)

Lactose intolerance (which causes problems after drinking milk and eating other dairy products)

Malabsorption syndromes

Less common causes of diarrhea include:

Carcinoid syndrome

Disorders of the nerves that supply the intestines

Removal of part of the stomach (gastrectomy) or small intestine

Radiation therapy

People who travel to developing countries can get diarrhea from unclean water or food that has not been handled safely. Plan ahead by learning the risks and treatment for traveler’s diarrhea before your trip.

Home Care For Diarrhea

Most times, you can treat diarrhea at home. You will need to learn:

To drink plenty of fluids to prevent dehydration (when your body does not have the proper amount of water and fluids)

Which foods you should or should not eat

What to do if you are breastfeeding

What danger signs to watch out for

Avoid medicines for diarrhea that you can buy without a prescription unless your provider tells you to use them. These drugs can make some infections worse.

If you have a long-term form of diarrhea, such as diarrhea caused by irritable bowel syndrome, changes to your diet and lifestyle may help.

When to Contact a Medical Professional

Contact your provider right away if you or your child shows signs of dehydration:

Decreased urine (fewer wet diapers in infants)

Dizziness or lightheadedness

Dry mouth

Sunken eyes

Few tears when crying

Schedule an appointment with your provider if you have:

Blood or pus in your stools

Black stools

Stomach pains

Stomach pain that does not go away after a bowel movement

Diarrhea with a fever above 101°F or 38.33°C (100.4°F or 38°C in children)

Recently traveled to a foreign country and developed diarrhea

Also contact your provider if:

The diarrhea gets worse or does not get better in 2 days for an infant or child, or 5 days for adults

A child over 3 months old has been vomiting for more than 12 hours; in younger babies, call as soon as vomiting or diarrhea begins

What to Expect at Your Hospital Visit

Your provider will perform a physical exam and ask about your medical history and symptoms.

Lab tests may be done on your stools to find the cause of your diarrhea.

Over-the-counter supplements that contain healthy bacteria may help prevent diarrhea caused by taking antibiotics. These are called probiotics. Yogurt with active or live cultures is also a good source of these healthy bacteria.

The following healthy steps can help you prevent illnesses that cause diarrhea:

Wash your hands often, particularly after using the toilet and before eating.

Use alcohol-based hand gel frequently.

Teach children to not put objects in their mouth.

Take steps to avoid food poisoning.

When traveling to underdeveloped areas, follow the steps below to avoid diarrhea:

Drink only bottled water and DO NOT use ice, unless it is made from bottled or purified water.

DO NOT eat uncooked vegetables or fruits that do not have peels.

DO NOT eat raw shellfish or undercooked meat.

DO NOT consume dairy products.

Peptic Ulcers

A peptic ulcer is an open sore or raw area in the lining of the stomach or intestine. The most common cause of ulcers is infection of the stomach by bacteria called Helicobacter pylori (H pylori). 

There are two types of peptic ulcers:

Gastric ulcer — occurs in the stomach

Duodenal ulcer — occurs in the first part of the small intestine


Normally, the lining of the stomach and small intestines can protect itself against strong stomach acids. But if the lining breaks down, the result may be:

Swollen and inflamed tissue (gastritis)

Most ulcers occur in the first layer of the inner lining. A hole in the stomach or duodenum is called a perforation. This is a medical emergency.

The most common cause of ulcers is infection of the stomach by bacteria called Helicobacter pylori (H pylori). Most people with peptic ulcers have these bacteria living in their digestive tract. Yet, many people who have these bacteria in their stomach do not develop an ulcer.

The following factors raise your risk for peptic ulcers:

Drinking too much alcohol

Regular use of aspirin, ibuprofen, naproxen, or other nonsteroidal anti-inflammatory drugs (NSAIDs)

Smoking cigarettes or chewing tobacco

Being very ill, such as being on a breathing machine

Radiation treatments


A rare condition, called Zollinger-Ellison syndrome, causes stomach and duodenal ulcers.

Symptoms of Ulcers

 Small ulcers may not cause any symptoms. Some ulcers can cause serious bleeding.
Abdominal pain (often in the upper mid-abdomen) is a common symptom. The pain can differ from person to person. Some people have no pain.

Pain occurs:

In the upper abdomen.

At night and wakes you up

When you feel an empty stomach, often 1 to 3 hours after a meal

Other symptoms include:

Feeling of fullness and problems drinking as much fluid as usual



Bloody or dark, tarry stools

Chest pain


Vomiting, possibly bloody

Weight loss

Ongoing heartburn

Exams and Tests

To detect an ulcer, you may need a test called an upper endoscopy (EGD).

This is a test to check the lining of the esophagus (food pipe), stomach, and first part of the small intestine.

It is done with a small camera (flexible endoscope) that is inserted down the throat.

This test most often requires sedation given through a vein.

In some cases, a smaller endoscope may be used that is passed into the stomach through the nose. This does not require sedation.

EGD is done on most people when peptic ulcers are suspected or when you have:

Low blood count (anemia)

Trouble swallowing

Bloody vomit

Bloody or dark and tarry-looking stools

Lost weight without trying

Other findings that raise a concern for cancer in the stomach

Testing for H pylori  is also needed. This may be done by biopsy of the stomach during endoscopy, with a stool test, or by a urea breath test.

Other tests you may have include:

Hemoglobin blood test to check for anemia

Stool occult blood test to test for blood in your stool

Sometimes, you may need a test called an upper GI series. A series of x-rays are taken after you drink a thick substance called barium. This does not require sedation.

Treatment of Peptic Ulcer Disease

Your health care provider will recommend medicines to heal your ulcer and prevent a relapse.

The medicines will:

Kill the H pylori bacteria, if present.

Reduce acid levels in the stomach. These include H2 blockers such as ranitidine (Zantac), or a proton pump inhibitor (PPI) such as omeprazole (Prilosec), lansoprazole (Prevacid), esomeprazole (Nexium), rabeprazole (AcipHex) or pantoprazole (Protonix).

Take all of your medicines as you have been told. Other changes in your lifestyle can also help.

If you have a peptic ulcer with an H pylori infection,

he standard treatment uses different combinations of the following medicines for 7 to 14 days:

Two different antibiotics to kill H pylori.

PPIs such as omeprazole (Prilosec), lansoprazole (Prevacid), or esomeprazole (Nexium).

Bismuth subsalicylate (the main ingredient in Pepto-Bismol) may be added to help kill the bacteria.

You will likely need to take a PPI for 8 weeks if:

You have an ulcer without an H pylori infection.

Your ulcer is caused by taking aspirin or NSAIDs.

Your provider may also prescribe this type of medicine regularly if you continue taking aspirin or NSAIDs for other health conditions.

Other medicines used for ulcers are:

Misoprostol, a medicine that may help prevent ulcers in people who take NSAIDs on a regular basis

Medicines that protect the tissue lining, such as sucralfate


Peptic ulcers tend to come back if untreated. There is a good chance that the H pylori infection will be cured if you take your medicines and follow your provider’s advice. You will be much less likely to get another ulcer.

Possible Complication Of Ulcers

Complications may include:

Severe blood loss

Scarring from an ulcer may make it harder for the stomach to empty

Perforation or hole of the stomach and intestines

When to See a Doctor

Get medical help right away if you:

Develop sudden, sharp abdominal pain

Have a rigid, hard abdomen that is tender to touch

Have symptoms of shock, such as fainting, excessive sweating, or confusion

Vomit blood or have blood in your stool (especially if it is maroon or dark, tarry black)

You feel dizzy or lightheaded.

You have ulcer symptoms.


Avoid aspirin, ibuprofen, naproxen, and other NSAIDs. Try acetaminophen instead. If you must take such medicines, talk to your provider first.

The following lifestyle changes may help prevent peptic ulcers:

DO NOT smoke or chew tobacco.

Avoid alcohol.