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Penicillin research questions

Tests and diagnosis

By Mayo Clinic Staff

A thorough exam and appropriate diagnostic tests are essential for an accurate diagnosis. Research has shown that penicillin allergies may be overdiagnosed and that patients may report a penicillin allergy that has never been confirmed. A misdiagnosed penicillin allergy may result in the use of less appropriate or more expensive antibiotics.

Your doctor will conduct a physical examination and ask you questions. Details about the onset of symptoms, the time you took medications, and improvement or worsening of symptoms are important clues for helping your doctor make a diagnosis.

Your doctor may order additional tests or refer you to an allergy specialist (allergist) for tests. These may include the following.

Skin tests

With a skin test, the allergist or nurse administers a small amount of the suspect penicillin to your skin either with a tiny needle that scratches the skin or an injection. A positive reaction to a test will cause a red, itchy, raised bump.

A positive result indicates a high likelihood of penicillin allergy. A negative test result usually means you're not allergic to penicillin, but a negative result is more difficult to interpret because some kinds of drug reactions cannot be detected by skin tests.

Graded challenge

If the diagnosis of a penicillin allergy is uncertain or your doctor judges an allergy unlikely based on the symptoms and test results, he or she may recommend a graded drug challenge.

With this procedure, you receive four to five doses of the suspect penicillin, starting with a small dose and increasing to the desired dose. If you reach the therapeutic dose with no reaction, then your doctor will conclude you aren't allergic to that type of penicillin. You will be able to take the drug as prescribed.

Similarly, if you are allergic to one type of penicillin, your doctor may recommend a graded challenge with a type of penicillin or cephalosporin that's less likely — because of known chemical properties — to cause an allergic reaction. This would enable your doctor to identify an antibiotic that can be used safely for a current bacterial infection and guide choices in future treatments.

During a drug challenge, your doctor provides careful supervision, and supportive care services are available to treat an adverse reaction.

  • Preparing for your appointment
  • Treatments and drugs
Nov. 22, 2014


  1. Romano A, et al. Antibiotic allergies in children and adults: From clinical symptoms to skin testing diagnosis. The Journal of Allergy and Clinical Immunology in Practice. 2014;2:3.
  2. Pichichero ME, et al. Penicillin and cephalosporin allergy. Annals of Allergy, Asthma & Immunology. 2014;112:404.
  3. Romano A, et al. Antibiotic allergy. Immunology and Allergy Clinics of North America. 2014;34:489.
  4. Anaphylaxis. The Merck Manual Professional Edition. http://www.merckmanuals.com/professional/immunology_allergic_disorders/allergic_autoimmune_and_other_hypersensitivity_disorders/anaphylaxis.html?qt=anaphylaxis&alt=sh. Accessed Aug. 10, 2014.
  5. Joint Task Force on Practice Parameter. Drug allergy: An updated practice parameter. Annals of Allergy, Asthma & Immunology. 2010;105:259.
  6. Chiriac AM, et al. Drug allergy diagnosis. Immunology and Allergy Clinics of North America. 2014;34:461.
  7. Beta-lactams. The Merck Manual Professional Edition. http://www.merckmanuals.com/professional/infectious_diseases/bacteria_and_antibacterial_drugs/β-lactams.html?qt=lactams&alt=sh. Accessed Oct. 6, 2014.
  8. Adkinson NF, et al. Middleton's Allergy: Principles and Practice. 8th ed. Philadelphia, Pa.: Saunders Elsevier; 2014. http://www.clinicalkey.com. Accessed July 22, 2014.
  9. Drug reactions and drug allergies. American College of Allergy, Asthma & Immunology. http://www.acaai.org/allergist/ALLERGIES/TYPES/DRUG-ALLERGY/Pages/default.aspx. Accessed July 22, 2014.
  10. Solensky R, et al. Evaluation of antibiotic allergy: The role of skin tests and drug challenges. Current Allergy and Asthma Reports. 2014;14:459.
  11. Drug hypersensitivity. The Merck Manual Professional Edition. http://www.merckmanuals.com/professional/immunology_allergic_disorders/allergic_autoimmune_and_other_hypersensitivity_disorders/drug_hypersensitivity.html?qt=drug sensitivity&alt=sh. Accessed July 22, 2104.
  12. Solensky R. Allergy to penicillins. http://www.uptodate.com/home. Accessed Oct. 6, 2014.

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Answer: Fleming died of a heart attack on 11 March 1955 in London, United Kingdom. He was cremated and his ashes were interred at St Paul's Cathedral.

Question: Who were his parents?

Answer: His parents were Hugh Fleming and Grace Morton, both farmers.

Question: Did he have any sisters and brothers?

Answer: Fleming had three siblings (Grace, John and Robert) and four half-siblings who were the surviving children from his father Hugh's first marriage (Jane, Hugh, Thomas and Mary).

Question: Where did he receive his education?

Answer: Fleming went to Loudoun Moor School and Darvel School, and then to Kilmarnock Academy. He moved to London in 1895 at the age of 13 years, and completed his compulsory schooling at Regent Street Polytechnic, London, in 1897. In 1901 he became a student at St Mary's Hospital Medical School, from where he graduated in 1906.

Question: What did he do for a living?

Answer: After finishing school at the age of 16, Fleming spent 4 years working at a shipping office before going to St Mary's Hospital Medical School in 1901 to study medicine.

Question: When was he knighted?

Answer: He was knighted in 1944 by King George VI of the United Kingdom and could from then on address himself as Sir Alexander Fleming.

Question: Is the story true that goes around attributing his good fortune to that of a wealthy man whose son he saved.

Answer: The story is false.

Question: What impact had the discovery of penicillin to the world?

Answer: Penicillin has saved millions of lives by stopping the growth of the bacteria that are responsible for poisoning the blood and causing many other once fatal diseases.


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