The antimicrobial spectrum of an

antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy ...

means the range of

microorganism A microorganism, or microbe, is an organism of microscopic scale, microscopic size, which may exist in its unicellular organism, single-celled form or as a Colony (biology)#Microbial colonies, colony of cells. The possible existence of unseen ...

s it can kill or inhibit. Antibiotics can be divided into

broad-spectrum antibiotic A broad-antimicrobial spectrum, spectrum antibiotic is an antibiotic that acts on the two major bacterial groups, Gram-positive and Gram-negative, or any antibiotic that acts against a wide range of disease-causing bacteria. These medications are ...

s, extended-spectrum antibiotics and

narrow-spectrum antibiotic A narrow-spectrum antibiotic is an antibiotic that is only able to kill or inhibit limited species of bacteria. Examples of narrow-spectrum antibiotics include fidaxomicin and sarecycline Sarecycline, sold under the brand name Seysara, is a ...

s based on their spectrum of activity. Detailedly, broad-spectrum antibiotics can kill or inhibit a wide range of microorganisms; extended-spectrum antibiotic can kill or inhibit Gram positive bacteria and some

Gram negative bacteria Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists of ...

; narrow-spectrum antibiotic can only kill or inhibit limited species of bacteria. Currently no antibiotic's spectrum can completely cover all types of microorganisms.

Determination

The antimicrobial spectrum of an antibiotic can be determined by testing its antimicrobial activity against a wide range of microbes ''

in vitro ''In vitro'' (meaning ''in glass'', or ''in the glass'') Research, studies are performed with Cell (biology), cells or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in ...

''. Nonetheless, the range of microorganisms which an antibiotic can kill or inhibit ''in vivo'' may not always be the same as the antimicrobial spectrum based on data collected in vitro.

Significance

Narrow-spectrum antibiotic A narrow-spectrum antibiotic is an antibiotic that is only able to kill or inhibit limited species of bacteria. Examples of narrow-spectrum antibiotics include fidaxomicin and sarecycline Sarecycline, sold under the brand name Seysara, is a ...

s have low propensity to induce bacterial resistance and are less likely to disrupt the

microbiome A microbiome () is the community of microorganisms that can usually be found living together in any given habitat. It was defined more precisely in 1988 by Whipps ''et al.'' as "a characteristic microbial community occupying a reasonably wel ...

(normal microflora). On the other hand, indiscriminate use of

s may not only induce the development of bacterial resistance and promote the emergency of multidrug-resistant organisms, but also cause off-target effects due to

dysbiosis Dysbiosis (also called dysbacteriosis) is characterized by a disruption to the microbiome resulting in an imbalance in the microbiota, changes in their functional composition and metabolic activities, or a shift in their local distribution. For e ...

. They may also have side effects, such as diarrhea or rash. Generally, a broad antibiotic has more clinical indications, and therefore are more widely used. The Healthcare Infection Control Practices Advisory Committee (HICPAC) recommends the use of narrow-spectrum antibiotics whenever possible.

Examples

* Broad-spectrum antibiotic:

Ciprofloxacin Ciprofloxacin is a fluoroquinolone antibiotic used to treat a number of bacterial infections. This includes bone and joint infections, intra-abdominal infections, certain types of infectious diarrhea, respiratory tract infections, skin ...

Doxycycline Doxycycline is a Broad-spectrum antibiotic, broad-spectrum antibiotic of the Tetracycline antibiotics, tetracycline class used in the treatment of infections caused by bacteria and certain parasites. It is used to treat pneumonia, bacterial p ...

, Minocycline,

Tetracycline Tetracycline, sold under various brand names, is an antibiotic in the tetracyclines family of medications, used to treat a number of infections, including acne, cholera, brucellosis, plague, malaria, and syphilis. It is available in oral an ...

Imipenem Imipenem (trade name Primaxin among others) is a synthetic beta-lactam, β-lactam antibiotic belonging to the carbapenems chemical class. developed by Merck scientists Burton Christensen, William Leanza, and Kenneth Wildonger in the mid-1970s. Car ...

Azithromycin Azithromycin, sold under the brand names Zithromax (in oral form) and Azasite (as an eye drop), is an antibiotic medication used for the treatment of several bacterial infections. This includes otitis media, middle ear infections, strep throa ...

* Extended-spectrum antibiotic:

Ampicillin Ampicillin is an antibiotic belonging to the aminopenicillin class of the penicillin family. The drug is used to prevent and treat several bacterial infections, such as respiratory tract infections, urinary tract infections, meningitis, s ...

* Narrow-spectrum antibiotic:

Sarecycline Sarecycline, sold under the brand name Seysara, is a narrow-spectrum tetracycline-derived antibiotic medication. It is specifically designed for the treatment of acne, and was approved by the FDA in October 2018 for the treatment of inflammat ...

Vancomycin Vancomycin is a glycopeptide antibiotic medication used to treat certain bacterial infections. It is administered intravenously ( injection into a vein) to treat complicated skin infections, bloodstream infections, endocarditis, bone an ...

Isoniazid Isoniazid, also known as isonicotinic acid hydrazide (INH), is an antibiotic used for the treatment of tuberculosis. For active tuberculosis, it is often used together with rifampicin, pyrazinamide, and either streptomycin or ethambutol. F ...

References

External links

Healthcare Infection Control Practices Advisory Committee (HICPAC)
{{Medicine, state=collapsed Antibiotics Clinical pharmacology

Determination

Significance

Examples

See also

References

External links