Broad-spectrum antibiotic

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A colored electron microscopy image of methicillin-resistant staphylococcus aureus (MRSA), a bacterium commonly targeted by broad-spectrum antibiotics Neutrophil MRSA II.jpg
A colored electron microscopy image of methicillin-resistant staphylococcus aureus (MRSA), a bacterium commonly targeted by broad-spectrum antibiotics

A broad-spectrum antibiotic is an antibiotic that acts on the two major bacterial groups, Gram-positive and Gram-negative, [1] or any antibiotic that acts against a wide range of disease-causing bacteria. [2] These medications are used when a bacterial infection is suspected but the group of bacteria is unknown (also called empiric therapy) or when infection with multiple groups of bacteria is suspected. This is in contrast to a narrow-spectrum antibiotic, which is effective against only a specific group of bacteria. [3] Although powerful, broad-spectrum antibiotics pose specific risks, particularly the disruption of native, normal bacteria and the development of antimicrobial resistance. An example of a commonly used broad-spectrum antibiotic is ampicillin. [3]

Contents

Bacterial targets

Antibiotics are often grouped by their ability to act on different bacterial groups. Although bacteria are biologically classified using taxonomy, disease-causing bacteria have historically been classified by their microscopic appearance and chemical function. The morphology of the organism may be classified as cocci, diplococci, bacilli (also known as "rods"), spiral-shaped or pleomorphic. Additional classification occurs through the organism's ability to take up the Gram stain and counter-stain; bacteria that take up the crystal violet dye stain are referred to as "gram-positive," those that take up the counterstain only are "gram-negative," and those that remain unstained are referred to as "atypical." Further classification includes their requirement for oxygen (i.e., aerobic or anaerobic), patterns of hemolysis, or other chemical properties. The most commonly encountered groupings of bacteria include gram-positive cocci, gram-negative bacilli, atypical bacteria, and anaerobic bacteria. [4] Antibiotics are often grouped by their ability to act on different bacterial groups. For example, 1st-generation cephalosporins are primarily effective against gram-positive bacteria, while 4th-generation cephalosporin s are generally effective against gram-negative bacteria.[ citation needed ]

Empiric antibiotic therapy

Simplified diagram showing common disease-causing bacteria and the antibiotics which act against them. 2023-12-12 Antibiotics Coverage Diagram.jpg
Simplified diagram showing common disease-causing bacteria and the antibiotics which act against them.

Empiric antibiotic therapy refers to the use of antibiotics to treat a suspected bacterial infection despite lack of a specific bacterial diagnosis. Definitive diagnosis of the species of bacteria often occurs through culture of blood, sputum, or urine, and can be delayed by 24 to 72 hours. [5] Antibiotics are generally given after the culture specimen has been taken from the patient in order to preserve the bacteria in the specimen and ensure accurate diagnosis. [4] Alternatively, some species may be identified through a urine or stool test. [4]

Risks

Disruption of normal microbiome

There are an estimated 38 trillion microorganisms that colonize the human body. [6] As a side-effect of therapy, 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. [7] The destruction of the body's normal bacterial flora is thought to disrupt immunity, nutrition, and lead to a relative overgrowth in some bacteria or fungi. [8] An overgrowth of drug-resistant microorganisms can lead to a secondary infection such as Clostridioides difficile ("C. diff") or candidiasis ("thrush"). [3] This side-effect is more likely with the use of broad-spectrum antibiotics, given their greater potential to disrupt a larger variety of normal human flora. [7] The use of doxycycline in acne vulgaris has been associated with increased risk of Crohn's disease, [9] although a later study indicated a link between acne vulgaris and IBS irrespective of the use of antibiotics. [10] Likewise, the use of minocycline in acne vulgaris has been associated with skin and gut dysbiosis. [11]

Examples of broad-spectrum antibiotics

In humans:[ citation needed ]

In veterinary medicine, co-amoxiclav, (in small animals); penicillin & streptomycin and oxytetracycline (in farm animals); penicillin and potentiated sulfonamides (in horses).

Related Research Articles

<span class="mw-page-title-main">Amoxicillin</span> Beta-lactam antibiotic

Amoxicillin is an antibiotic medication belonging to the aminopenicillin class of the penicillin family. The drug is used to treat bacterial infections such as middle ear infection, strep throat, pneumonia, skin infections, odontogenic infections, and urinary tract infections. It is taken by mouth, or less commonly by injection.

<span class="mw-page-title-main">Beta-lactamase</span> Class of enzymes

Beta-lactamases (β-lactamases) are enzymes produced by bacteria that provide multi-resistance to beta-lactam antibiotics such as penicillins, cephalosporins, cephamycins, monobactams and carbapenems (ertapenem), although carbapenems are relatively resistant to beta-lactamase. Beta-lactamase provides antibiotic resistance by breaking the antibiotics' structure. These antibiotics all have a common element in their molecular structure: a four-atom ring known as a beta-lactam (β-lactam) ring. Through hydrolysis, the enzyme lactamase breaks the β-lactam ring open, deactivating the molecule's antibacterial properties.

<span class="mw-page-title-main">Gram-negative bacteria</span> Group of bacteria that do not retain the Gram stain used in bacterial differentiation

Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is their cell envelope, which consists of a thin peptidoglycan cell wall sandwiched between an inner (cytoplasmic) membrane and an outer membrane. These bacteria are found in all environments that support life on Earth.

<span class="mw-page-title-main">Minocycline</span> Antibiotic medication

Minocycline, sold under the brand name Minocin among others, is a tetracycline antibiotic medication used to treat a number of bacterial infections such as pneumonia. It is generally less preferred than the tetracycline doxycycline. Minocycline is also used for the treatment of acne and rheumatoid arthritis. It is taken by mouth or applied to the skin.

<i>Cutibacterium acnes</i> Species of bacterium

Cutibacterium acnes is the relatively slow-growing, typically aerotolerant anaerobic, gram-positive bacterium (rod) linked to the skin condition of acne; it can also cause chronic blepharitis and endophthalmitis, the latter particularly following intraocular surgery. Its genome has been sequenced and a study has shown several genes can generate enzymes for degrading skin and proteins that may be immunogenic.

<span class="mw-page-title-main">Doxycycline</span> Tetracycline-class antibiotic

Doxycycline is a broad-spectrum antibiotic of the tetracycline class used in the treatment of infections caused by bacteria and certain parasites. It is used to treat bacterial pneumonia, acne, chlamydia infections, Lyme disease, cholera, typhus, and syphilis. It is also used to prevent malaria. Doxycycline may be taken by mouth or by injection into a vein.

<span class="mw-page-title-main">Cephalosporin</span> Class of pharmaceutical drugs

The cephalosporins are a class of β-lactam antibiotics originally derived from the fungus Acremonium, which was previously known as Cephalosporium.

<span class="mw-page-title-main">Tigecycline</span> Chemical compound

Tigecycline, sold under the brand name Tygacil, is a tetracycline antibiotic medication for a number of bacterial infections. It is a glycylcycline administered intravenously. It was developed in response to the growing rate of antibiotic resistant bacteria such as Staphylococcus aureus, Acinetobacter baumannii, and E. coli. As a tetracycline derivative antibiotic, its structural modifications has expanded its therapeutic activity to include Gram-positive and Gram-negative organisms, including those of multi-drug resistance.

<span class="mw-page-title-main">Carbapenem</span> Class of highly effective antibiotic agents

Carbapenems are a class of very effective antibiotic agents most commonly used for treatment of severe bacterial infections. This class of antibiotics is usually reserved for known or suspected multidrug-resistant (MDR) bacterial infections. Similar to penicillins and cephalosporins, carbapenems are members of the beta-lactam antibiotics drug class, which kill bacteria by binding to penicillin-binding proteins, thus inhibiting bacterial cell wall synthesis. However, these agents individually exhibit a broader spectrum of activity compared to most cephalosporins and penicillins. Furthermore, carbapenems are typically unaffected by emerging antibiotic resistance, even to other beta-lactams.

Community-acquired pneumonia (CAP) refers to pneumonia contracted by a person outside of the healthcare system. In contrast, hospital-acquired pneumonia (HAP) is seen in patients who have recently visited a hospital or who live in long-term care facilities. CAP is common, affecting people of all ages, and its symptoms occur as a result of oxygen-absorbing areas of the lung (alveoli) filling with fluid. This inhibits lung function, causing dyspnea, fever, chest pains and cough.

Ampicillin/sulbactam is a fixed-dose combination medication of the common penicillin-derived antibiotic ampicillin and sulbactam, an inhibitor of bacterial beta-lactamase. Two different forms of the drug exist. The first, developed in 1987 and marketed in the United States under the brand name Unasyn, generic only outside the United States, is an intravenous antibiotic. The second, an oral form called sultamicillin, is marketed under the brand name Ampictam outside the United States, and generic only in the United States. Ampicillin/sulbactam is used to treat infections caused by bacteria resistant to beta-lactam antibiotics. Sulbactam blocks the enzyme which breaks down ampicillin and thereby allows ampicillin to attack and kill the bacteria.

<span class="mw-page-title-main">Tetracycline antibiotics</span> Type of broad-spectrum antibiotic

Tetracyclines are a group of broad-spectrum antibiotic compounds that have a common basic structure and are either isolated directly from several species of Streptomyces bacteria or produced semi-synthetically from those isolated compounds. Tetracycline molecules comprise a linear fused tetracyclic nucleus to which a variety of functional groups are attached. Tetracyclines are named after their four ("tetra-") hydrocarbon rings ("-cycl-") derivation ("-ine"). They are defined as a subclass of polyketides, having an octahydrotetracene-2-carboxamide skeleton and are known as derivatives of polycyclic naphthacene carboxamide. While all tetracyclines have a common structure, they differ from each other by the presence of chloro, methyl, and hydroxyl groups. These modifications do not change their broad antibacterial activity, but do affect pharmacological properties such as half-life and binding to proteins in serum.

Dysbiosis 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 example, a part of the human microbiota such as the skin flora, gut flora, or vaginal flora, can become deranged, with normally dominating species underrepresented and normally outcompeted or contained species increasing to fill the void. Dysbiosis is most commonly reported as a condition in the gastrointestinal tract.

β-Lactamase inhibitor Family of enzymes

Beta-lactamases are a family of enzymes involved in bacterial resistance to beta-lactam antibiotics. In bacterial resistance to beta-lactam antibiotics, the bacteria have beta-lactamase which degrade the beta-lactam rings, rendering the antibiotic ineffective. However, with beta-lactamase inhibitors, these enzymes on the bacteria are inhibited, thus allowing the antibiotic to take effect. Strategies for combating this form of resistance have included the development of new beta-lactam antibiotics that are more resistant to cleavage and the development of the class of enzyme inhibitors called beta-lactamase inhibitors. Although β-lactamase inhibitors have little antibiotic activity of their own, they prevent bacterial degradation of beta-lactam antibiotics and thus extend the range of bacteria the drugs are effective against.

<span class="mw-page-title-main">Nadifloxacin</span> Chemical compound

Nadifloxacin is a topical fluoroquinolone antibiotic for the treatment of acne vulgaris. It is also used to treat bacterial skin infections.

<span class="mw-page-title-main">Antibiotic misuse</span>

Antibiotic misuse, sometimes called antibiotic abuse or antibiotic overuse, refers to the misuse or overuse of antibiotics, with potentially serious effects on health. It is a contributing factor to the development of antibiotic resistance, including the creation of multidrug-resistant bacteria, informally called "super bugs": relatively harmless bacteria can develop resistance to multiple antibiotics and cause life-threatening infections.

Infections caused by exposure to ionizing radiation can be extremely dangerous, and are of public and government concern. Numerous studies have demonstrated that the susceptibility of organisms to systemic infection increased following exposure to ionizing radiation. The risk of systemic infection is higher when the organism has a combined injury, such as a conventional blast, thermal burn, or radiation burn. There is a direct quantitative relationship between the magnitude of the neutropenia that develops after exposure to radiation and the increased risk of developing infection. Because no controlled studies of therapeutic intervention in humans are available, almost all of the current information is based on animal research.

<span class="mw-page-title-main">Antimicrobial spectrum</span> Method of assessing antibiotics

The antimicrobial spectrum of an antibiotic means the range of microorganisms it can kill or inhibit. Antibiotics can be divided into broad-spectrum antibiotics, extended-spectrum antibiotics and narrow-spectrum antibiotics 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; narrow-spectrum antibiotic can only kill or inhibit limited species of bacteria.

References

  1. ↑ Ory EM, Yow EM (July 1963). "The use and abuse of the broad spectrum antibiotics". JAMA. 185 (4): 273–9. doi:10.1001/jama.1963.03060040057022. PMID   13940450.
  2. ↑ Clayton L. Thomas, ed. (1993). Taber's Cyclopedic Medical Dictionary (17th ed.). F. A. Davis Co. ISBN   978-0-8036-8313-6.
  3. 1 2 3 Hopkins SJ (1997). Drugs and Pharmacology for Nurses (12th ed.). Churchill Livingstone. ISBN   978-0-443-05249-1.
  4. 1 2 3 Kasper DL, Larry Jameson J, Hauser SL, Loscalzo J, Fauci AS, Longo DL (2015-04-08). Harrison's principles of internal medicine (19th ed.). New York. ISBN   9780071802154. OCLC   893557976.{{cite book}}: CS1 maint: location missing publisher (link)
  5. ↑ Leekha S, Terrell CL, Edson RS (February 2011). "General principles of antimicrobial therapy". Mayo Clinic Proceedings. 86 (2): 156–67. doi:10.4065/mcp.2010.0639. PMC   3031442 . PMID   21282489.
  6. ↑ Sender R, Fuchs S, Milo R (2016). "Revised Estimates for the Number of Human and Bacteria Cells in the Body". PLOS Biology. 14 (8): e1002533. doi: 10.1371/journal.pbio.1002533 . PMC   4991899 . PMID   27541692.
  7. 1 2 Martin EA (2003). Oxford Concise Medical Dictionary (6th ed.). Oxford University Press. ISBN   978-0-19-860753-3.
  8. ↑ Rafii F, Sutherland JB, Cerniglia CE (December 2008). "Effects of treatment with antimicrobial agents on the human colonic microflora". Therapeutics and Clinical Risk Management. 4 (6): 1343–58. doi: 10.2147/tcrm.s4328 . PMC   2643114 . PMID   19337440.
  9. ↑ Margolis, David J.; Fanelli, Matthew; Hoffstad, Ole; Lewis, James D. (2010). "Potential association between the oral tetracycline class of antimicrobials used to treat acne and inflammatory bowel disease". The American Journal of Gastroenterology. 105 (12): 2610–2616. doi:10.1038/ajg.2010.303. ISSN   1572-0241. PMID   20700115. S2CID   20085592.
  10. ↑ Taylor, Matthew T.; Margolis, David J.; Kwatra, Shawn G.; Barbieri, John S. (April 2023). "A propensity score matched cohort study identifying an association of acne, but not oral antibiotic or isotretinoin use, with risk of incident inflammatory bowel disease". Journal of the American Academy of Dermatology. 88 (4): 841–847. doi:10.1016/j.jaad.2023.01.014. ISSN   1097-6787. PMC  10033360. PMID   36682724.
  11. ↑ Thompson, Katherine G.; Rainer, Barbara M.; Antonescu, Corina; Florea, Liliana; Mongodin, Emmanuel F.; Kang, Sewon; Chien, Anna L. (2020-02-01). "Minocycline and Its Impact on Microbial Dysbiosis in the Skin and Gastrointestinal Tract of Acne Patients". Annals of Dermatology. 32 (1): 21–30. doi: 10.5021/ad.2020.32.1.21 . ISSN   1013-9087. PMC   7992645 . PMID   33911705.
  12. ↑ Coon ER, Quinonez RA, Morgan DJ, Dhruva SS, Ho T, Money N, Schroeder AR (April 2019). "2018 Update on Pediatric Medical Overuse: A Review". JAMA Pediatrics. 173 (4): 379–384. doi:10.1001/jamapediatrics.2018.5550. PMID   30776069. S2CID   73495617.
  13. ↑ McMullan BJ, Mostaghim M (June 2015). "Prescribing azithromycin". Australian Prescriber. 38 (3): 87–9. doi:10.18773/austprescr.2015.030. PMC   4653965 . PMID   26648627.
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