Classes of Antibiotics
Classes of antibiotics are categorized based on their chemical structure and mechanism of action. Common classes include penicillins, cephalosporins, tetracyclines, macrolides, and fluoroquinolones. Each class targets specific bacterial components or processes, such as cell wall synthesis or protein production, making them effective against different types of bacteria. Understanding these classes is crucial for selecting the most appropriate antibiotic for treating bacterial infections.
5 Key excerpts on "Classes of Antibiotics"
eBook - ePub- David B. Wilson, Hermann Sahm, Klaus-Peter Stahmann, Mattheos Koffas, David B. Wilson, Hermann Sahm, Klaus-Peter Stahmann, Mattheos Koffas(Authors)
- 2019(Publication Date)
- Wiley-VCH(Publisher)
...Macrolide antibiotics possess a similar activity profile to β‐lactam compounds and are commonly prescribed as substitutes for patients allergic to penicillin. Aminoglycosides offer an alternative activity profile relative to most β‐lactam and macrolide compounds and are, thus, used to treat a different spectrum of infectious diseases. Tetracycline compounds have shown activity across a broader array of microbial hosts and, as such, this and similar compounds are referred to as “broad spectrum” antibiotics. Table 8.2 Antibiotics discovered across decades and natural product classifications. Decade Antibiotic Classification 1920s Penicillin β‐Lactam 1940s Tetracycline Tetracycline 1940s Cephalexin β‐Lactam (cephalosporins) 1950s Erythromycin Macrolide 1960s Tobramycin Aminoglycoside 1970s Imipenem β‐Lactam (carbapenems) 1980s Daptomycin Cyclic lipopeptide 1980s Azithromycin Macrolide As will be described in more detail below, the microbes responsible for infectious disease possess either native or mutation‐based properties that render antibiotic compounds more or less effective. As such, antibiotic compound activity (as surveyed within Figure 8.2) is directed at appropriate microbial infectious disease targets. As additional examples, streptomycin is commonly used to treat tuberculosis, whereas daptomycin has shown activity toward the same types of bacteria susceptible to penicillins (termed Gram‐positive bacteria) with activity against an antibiotic resistant form of Staphylococcus aureus (termed methicillin‐resistant Staphylococcus aureus [ MRSA ]). The following sections will now go into more detail regarding the classifications of natural products that have emerged around biosynthetic mechanisms, compound structure, and therapeutic function. 8.2 β‐Lactams 8.2.1 History, Effect, and Application β‐Lactams represent a historic contributor to antibiotic natural product utility...
eBook - ePub- Mark Currivan(Author)
- 2021(Publication Date)
- Wiley-Blackwell(Publisher)
...9 Antimicrobials: drugs used to treat infectious diseases Antibacterials (‘antibiotics’) Aminoglycosides Carbapenems Cephalosporins Compound antibiotics Folic acid inhibitors Lincosamides Lipopeptides and glycopeptides Macrocyclic antibiotics Macrolides Nitrofuran derivatives Nitroimidazoles Oxazolidinones Penicillins Quinolones Rifamycins Sulfonamides Tetracyclines and glycylcyclines Antifungals Echinocandin class Imidazole class Polyene class Triazole class Antivirals Fusion (entry) inhibitors HCV inhibitors Interferons Integrase inhibitors Neuraminidase inhibitors Nucleoside analogues Nucleotide analogues Nucleoside reverse transcriptase inhibitors Non‐nucleoside reverse transcriptase inhibitors Phosphonic acid derivatives Protease inhibitors (hepatitis C and HIV‐affecting) Antibacterials Antibacterials (commonly called ‘antibiotics’) are drugs given to treat a bacterial infection (as distinct from a fungal or viral infection). The emergence of effective antibacterial agents, in particular, Fleming's discovery of penicillin and its subsequent development by Florey, Chain, Heatley and others, proved to be the most important pharmaceutical breakthrough of the twentieth century. More lives have been saved because of treatment with antibiotics than with any other type of medicine in history. There are many types of antibacterial agent, with specific types required to treat specific kinds of bacteria. Listed in this section are most (but not all) of the antibacterials in current use. Aminoglycosides Aminoglycosides have a broad spectrum of activity and are used to treat both Gram‐negative and Gram‐positive organisms. Aminoglycosides have names ending with ‘‐ ka cin ’, ‘‐ mi cin ’ or ‘‐ my cin ’...
eBook - ePub- Kristian Stromgaard, Povl Krogsgaard-Larsen, Ulf Madsen, Kristian Stromgaard, Povl Krogsgaard-Larsen, Ulf Madsen(Authors)
- 2016(Publication Date)
- CRC Press(Publisher)
...Members of this class share the common β-lactam (four-membered cyclic amide) ring structure (Table 23.1) which is the active pharmacophore. Their mode of action is indicated in Table 23.2. FIGURE 23.1 Antibiotic introduction and resistance timeline: The year of clinical introduction of key antibiotics is shown (a) along with their structural class (b). The horizontal bars indicate the duration between introduction and the first observation of clinical resistance. Absence of the horizontal bars indicates that resistance was observed in the year the antibiotic was introduced. Antibiotics are color-coded to indicate the essential bacterial process they target. (Data partly from Walsh, C.T. and Wencewicz, T.A., J. Antibiot., 67, 7, 2014.) FIGURE 23.2 Schematic representation of the structure of the bacterial cell walls. (a) Gram + bacteria have a thick peptidoglycan layer surrounding the plasma membrane. (c) Gram − bacteria have a thin peptidoglycan layer that is surrounded by a lipid-rich bilayer outer membrane. Sandwiched between the plasma membrane and the outermembrane in Gram − bacteria is a concentrated gel-like matrix (periplasm) present in periplasmic space. (b) The mycobacterial cell wall is much thicker than that of other bacteria and is hydrophobic. It consists of peptidoglycan, arabinogalactan, and mycolic acids covalently linked together to form a complex that extends from the plasma membrane outward in layers, starting with the peptidoglycan and ending with mycolic acid. 23.3.1.1 Penicillins England and the United States made significant efforts to produce sufficient quantities of penicillin and elucidate its structure (1942–1945). Addition of corn steep liquor increased penicillin production yielding penicillin G that has a benzyl side chain. When substituted with phenoxyethanol as precursor, phenoxymethyl penicillin (penicillin V) was obtained. Penicillin V was unexpectedly acid stable and was introduced as oral penicillin...
- Frank M. Aarestrup, Stefan Schwarz, Lina Maria Cavaco, Jianzhong Shen, Stefan Schwarz, Lina Maria Cavaco, Jianzhong Shen(Authors)
- 2018(Publication Date)
- ASM Press(Publisher)
...4 Mechanisms of Bacterial Resistance to Antimicrobial Agents Engeline van Duijkeren, 1 Anne-Kathrin Schink, 2 Marilyn C. Roberts, 3 Yang Wang, 4 Stefan Schwarz 2 INTRODUCTION With regard to their structures and functions, antimicrobial agents represent a highly diverse group of low-molecular-weight substances which interfere with bacterial growth, resulting in either a timely limited growth inhibition (bacteriostatic effect) or the killing of the bacteria (bactericidal effect). For more than 60 years, antimicrobial agents have been used to control bacterial infections in humans, animals, and plants. Nowadays, antimicrobial agents are among the most frequently used therapeutics in human and veterinary medicine (1, 2). In the early days of antimicrobial chemotherapy, antimicrobial resistance was not considered as an important problem, since the numbers of resistant strains were low and a large number of new highly effective antimicrobial agents of different classes were detected. These early antimicrobial agents represented products of the metabolic pathways of soil bacteria (e.g., Streptomyces, Bacillus) or fungi (e.g., Penicillium, Cephalosporium, Pleurotus) (Table 1) and provided their producers with a selective advantage in the fight for resources and the colonization of ecological niches (3). This in turn forced the susceptible bacteria living in close contact with the antimicrobial producers to develop and/or refine mechanisms to circumvent the inhibitory effects of antimicrobial agents. As a consequence, the origins of bacterial resistance to antimicrobial agents can be assumed to be in a time long before the clinical use of these substances...
eBook - ePubAntibiotics
Challenges, Mechanisms, Opportunities
- Christopher Walsh, Timothy Wencewicz(Authors)
- 2016(Publication Date)
- ASM Press(Publisher)
...SECTIONIIIMechanisms: Bacterial Resistance to AntibioticsThe five chapters of section III take up a distinct aspect of antibiotic mechanisms. Whereas section II categorized the major classes of approved antibiotics according to the kinds of essential metabolic processes they interdict in pathogenic bacteria, section III deals with resistance.In terms of challenges, mechanisms, and opportunities, the continued emergence of multidrug-resistant bacterial pathogens represents the most obvious challenge to the ability to treat life-threatening bacterial infections. It follows that a knowledge of resistance mechanisms is crucial to the design and implementation of next-generation antibiotics as well as combinations of current antibiotics.Development of one or more forms of resistance to antibiotics is inescapably coupled to antibiotic mechanism of action. Almost as night follows day, the widespread use of an antibiotic in human clinical populations leads to emergence of resistant organisms as selection for rare, resistant bacterial genotypes occurs. While sensitive bacterial populations die off, the resistant forms, once rare, can become dominant members of the bacterial population. To understand how to discover and develop new antibiotics, the mechanisms of bacterial resistance must be deciphered.Chapter 9introduces the concepts of innate versus acquired resistance in bacterial species. The resistome as a reservoir of bacterial resistance genes in the environment is discussed, along with likely routes of evolution of housekeeping enzymes into resistance catalysts...
