The term broad-spectrum antibiotic refers to an antibiotic

Antibiotic

An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...

 that acts against a wide range of disease-causing bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

. A broad-spectrum antibiotic acts against both Gram-positive

Gram-positive

Gram-positive bacteria are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain and appearing red or pink...

 and Gram-negative

Gram-negative

Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...

 bacteria, in contrast to a narrow-spectrum antibiotic, which is effective against specific families of bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

. An example of a commonly used broad-spectrum antibiotic is ampicillin

Ampicillin

Ampicillin is a beta-lactam antibiotic that has been used extensively to treat bacterial infections since 1961. Until the introduction of ampicillin by the British company Beecham, penicillin therapies had only been effective against Gram-positive organisms such as staphylococci and streptococci...

.

Uses

Broad-spectrum antibiotics are properly used in the following medical

Medicine

Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

 situations:

• Empirically (i.e., based on the experience of the practitioner), prior to the formal identification of the causative bacteria, when there is a wide range of possible illnesses and a potentially serious illness would result if treatment is delayed. This occurs, for example, in meningitis
  Meningitis
  Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...
  
  , where the patient can become fatally ill within hours if broad-spectrum antibiotics are not initiated.

• For drug resistant bacteria that do not respond to other, more narrow-spectrum antibiotics.

• In the case of superinfection
  Superinfection
  In virology, superinfection is the process by which a cell, that has previously been infected by one virus, gets coinfected with a different strain of the virus, or another virus at a later point in time. Viral superinfections of serious conditions can lead to resistant strains of the virus, which...
  
  s, where there are multiple types of bacteria causing illness, thus warranting either a broad-spectrum antibiotic or combination antibiotic therapy.

Risks

As a side-effect, antibiotics can change the body's normal microbial content by attacking indiscriminately both the pathological and naturally-occurring, beneficial or harmless bacteria found in the intestines, lungs and bladder. The destruction of the body's normal bacterial flora

Flora

Flora is the plant life occurring in a particular region or time, generally the naturally occurring or indigenous—native plant life. The corresponding term for animals is fauna.-Etymology:...

 provides an opportunity for drug-resistant microorganisms to grow vigorously and can lead to a secondary infection such as Clostridium difficile

Clostridium difficile

Clostridium difficile , also known as "CDF/cdf", or "C...

 (also known as "C. diff") or Candidiasis

Candidiasis

Thrush redirects here. For the hoof infection see Thrush .Candidiasis or thrush is a fungal infection of any of the Candida species , of which Candida albicans is the most common...

 (also known as "thrush") in females. This side-effect is more likely with the use of broad-spectrum antibiotics.

Examples

In medicine

Medicine

Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

:

• amoxicillin
  Amoxicillin
  Amoxicillin , formerly amoxycillin , and abbreviated amox, is a moderate-spectrum, bacteriolytic, β-lactam antibiotic used to treat bacterial infections caused by susceptible microorganisms. It is usually the drug of choice within the class because it is better absorbed, following oral...
  
  
• levofloxacin
  Levofloxacin
  Levofloxacin is a synthetic chemotherapeutic antibiotic of the fluoroquinolone drug class and is used to treat severe or life-threatening bacterial infections or bacterial infections that have failed to respond to other antibiotic classes. It is sold under various brand names, such as Levaquin and...
  
  , gatifloxacin
  Gatifloxacin
  Gatifloxacin sold under the brand names Gatiflo, Tequin and Zymar, is an antibiotic of the fourth-generation fluoroquinolone family, that like other members of that family, inhibits the bacterial enzymes DNA gyrase and topoisomerase IV...
  
  , moxifloxacin
  Moxifloxacin
  Moxifloxacin is a fourth-generation synthetic fluoroquinolone antibacterial agent developed by Bayer AG . It is marketed worldwide under the brand names Avelox, Avalox, and Avelon for oral treatment. In most countries, the drug is also available in parenteral form for intravenous infusion...
  
  

In veterinary medicine

Veterinary medicine

Veterinary Medicine is the branch of science that deals with the prevention, diagnosis and treatment of disease, disorder and injury in non-human animals...

, Co-amoxiclav

Co-amoxiclav

Amoxicillin/clavulanic acid or co-amoxiclav is a combination antibiotic consisting of amoxicillin trihydrate, a β-lactam antibiotic, and potassium clavulanate, a β-lactamase inhibitor...

, (in small animals); penicillin

Penicillin

Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....

 & streptomycin

Streptomycin

Streptomycin is an antibiotic drug, the first of a class of drugs called aminoglycosides to be discovered, and was the first antibiotic remedy for tuberculosis. It is derived from the actinobacterium Streptomyces griseus. Streptomycin is a bactericidal antibiotic. Streptomycin cannot be given...

 and oxytetracycline

Oxytetracycline

Oxytetracycline was the second of the broad-spectrum tetracycline group of antibiotics to be discovered.Oxytetracycline works by interfering with the ability of bacteria to produce proteins that are essential to them. Without these proteins the bacteria cannot grow, multiply and increase in numbers...

 (in farm animals); penicillin

Penicillin

Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....

 and potentiated sulfonamides

Sulfonamide (medicine)

Sulfonamide or sulphonamide is the basis of several groups of drugs. The original antibacterial sulfonamides are synthetic antimicrobial agents that contain the sulfonamide group. Some sulfonamides are also devoid of antibacterial activity, e.g., the anticonvulsant sultiame...

 (in horses).

Others:

• streptomycin
  Streptomycin
  Streptomycin is an antibiotic drug, the first of a class of drugs called aminoglycosides to be discovered, and was the first antibiotic remedy for tuberculosis. It is derived from the actinobacterium Streptomyces griseus. Streptomycin is a bactericidal antibiotic. Streptomycin cannot be given...
  
  
• tetracycline
• chloramphenicol
  Chloramphenicol
  Chloramphenicol is a bacteriostatic antimicrobial that became available in 1949. It is considered a prototypical broad-spectrum antibiotic, alongside the tetracyclines, and as it is both cheap and easy to manufacture it is frequently found as a drug of choice in the third world.Chloramphenicol is...
  
  

Slightly-Broad:

• ampicillin
  Ampicillin
  Ampicillin is a beta-lactam antibiotic that has been used extensively to treat bacterial infections since 1961. Until the introduction of ampicillin by the British company Beecham, penicillin therapies had only been effective against Gram-positive organisms such as staphylococci and streptococci...