Penicillin (Antibiotics)

  • Pharmacy Author:
    Omudhome Ogbru, PharmD

    Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

  • Medical and Pharmacy Editor: Jay W. Marks, MD
    Jay W. Marks, MD

    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

Who discovered penicillin?

In 1928, Alexander Fleming noted that mold belonging to the genus Penicillium inhibited the growth of bacteria. Fleming called this unknown antibacterial substance penicillin. Ten years later, a group at Oxford University began to investigate penicillin in laboratory mice. Penicillin was hailed as a miracle drug and saved countless lives in World War II.

What are penicillin antibiotics?

Penicillins are antibiotics used to treat bacterial infections that are derived from the antibiotic penicillin.

What are the uses for penicillin antibiotics?

Today, many derivatives of penicillin have been developed that inhibit more types of bacteria than the original life-saving drug. Penicillin itself is active against

  • streptococci (including Streptococcus pneumoniae),
  • Listeria, Neisseria gonorrhoeae,
  • Clostridium,
  • Peptococcus, and
  • Peptostreptococcus.

However, most staphylococci now are resistant to penicillin.

Other penicillin antibiotics are effective against

  • H. influenzae,
  • E. coli, pneumococci,
  • certain strains of staphylococci,
  • Salmonella,
  • Shigella,
  • Pseudomonas aeruginosa, and
  • many other types of bacteria.

Penicillin antibiotics are used to treat many types of infections caused by susceptible bacteria. They are used to treat infections of the middle ear, sinuses, stomach and intestines, bladder, and kidney. They also are used for treating

What are examples of penicillin antibiotics available in the US?

  • penicillin V
  • penicillin G (Pfizerpen, Permapen)
  • amoxicillin (Amoxil)
  • amoxicillin/clavulonate (Augmentin)
  • ampicillin (Unasyn)
  • nafcillin (Nallpen)
  • oxacillin (Bactocill)
  • dicloxacillin (Dycill, Dynapen are discontinued brands in the US; generic is available)
  • cloxacillin (discontinued in the US)
  • piperacillin (Pipracil)
  • piperacillin/tazobactam (Zosyn)
  • ticarcillin (Ticar) (Discontinued in the US; ; generic is not available))
  • ticarcillin/clavulonate (Timentin) (Discontinued in the US and a generic is not available.)

What are the side effects of penicillin antibiotics?

Side effects of penicillin antibiotics include

Individuals who are allergic to the cephalosporin class of antibiotics, which are related to the penicillins, for example, cefaclor (Ceclor), cephalexin (Keflex), and cefprozil (Cefzil), may or may not be allergic to penicillins.

Serious but rare reactions include

Like other antibiotics, penicillin antibiotics can alter the normal bacteria in the colon and encourage overgrowth of some bacteria such as Clostridium difficile, which causes inflammation of the colon (C. difficile colitis or pseudomembranous colitis).

Signs and symptoms of C. difficile colitis include

Medically Reviewed by a Doctor on 12/9/2016
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