Bacterial Resistance to Antibiotics
Bacterial resistance to antibiotics refers to the ability of bacteria to withstand the effects of antibiotics, making the drugs ineffective in treating infections. This resistance can develop through genetic mutations or the acquisition of resistance genes from other bacteria. Overuse and misuse of antibiotics in both humans and animals contribute to the widespread occurrence of bacterial resistance.
7 Key excerpts on "Bacterial Resistance to Antibiotics"
eBook - ePubAntibiotics
Challenges, Mechanisms, Opportunities
- Christopher Walsh, Timothy Wencewicz(Authors)
- 2016(Publication Date)
- ASM Press(Publisher)
...Bacterial resistance is definable as continued growth in the presence of an antibiotic at concentrations that would normally halt growth and/or kill a sensitive bacterial cell.Intrinsic versus Acquired ResistanceThe mechanisms are varied, as we will see in the next three chapters that comprise this section. Four major categories are noted inFig. 9.1and9.2. Molecular mechanisms A to D in both figures reflect distinct coping strategies (Walsh, 2000). Active efflux of antibiotics by transmembrane protein pumps that span cytoplasmic membranes in Gram-positive organisms and both inner and outer membranes in Gram-negative organisms is examined in detail inchapter 11. The modification or destruction of antibiotics, typically by inducible enzymes, is the subject ofchapter 10.Chapter 12deals with the third major mechanism, alteration of the target of an antibiotic that requires reprogramming of bacterial biosynthetic machinery to produce a structure (e.g., cell wall or ribosome) that is still functional but no longer sensitive to a given antibiotic scaffold.Figure 9.1Schematic of antibiotic resistance mechanisms in bacteria. Genetic mechanisms 1 to 4 involve gene mutation and three routes for transfer of foreign genes (transformation, transduction, and conjugation). Molecular mechanisms A to D of resistance include exclusion by antibiotic efflux pumps, alteration of outer membrane porins, modification of antibiotic targets, and inactivating modifications of the antibiotic.Figure 9.2Major categories of antibiotic resistance. Susceptible Gram-negative bacteria take up antibiotic through wild-type (WT) porin, and the antibiotic inhibits the WT target. (a) Resistance via altered porin structure or abundance. (b) Resistance via active efflux. (c) Altered target in resistant mutants...
eBook - ePubAntibiotics and Antimicrobial Resistance Genes in the Environment
Volume 1 in the Advances in Environmental Pollution Research series
- Muhammad Zaffar Hashmi(Author)
- 2019(Publication Date)
- Elsevier(Publisher)
...Chapter 19 Antibiotics resistance mechanism Muhammad Naveed 1, Zoma Chaudhry 2, Syeda Aniqa Bukhari 2, Bisma Meer 3, and Hajra Ashraf 3 1 Department of Biotechnology, University of Central Punjab, Lahore, Punjab, Pakistan 2 Department of Biochemistry and Biotechnology, University of Gujrat, Gujrat, Punjab, Pakistan 3 Department of Biotechnology, Quaid-e-Azam University, Islamabad, Punjab, Pakistan Abstract Antibiotics are crucial in pharmaceuticals that are used against a broad range of bacteria to reduce their growth in living organisms. Antibiotics have been known for the last 30 years approximately according to their function and classification as antibiotics have been around for a lot longer!!. In working, antibiotics act as part of immune system and target bacterial cells specifically. Similarly, on detection of certain immune signals within living cells, antibiotics detect harmful pathogens and act against them. Broad-spectrum antibiotics affect both gram-positive and gram-negative bacteria, causing serious illnesses in human beings. But gradually, with passage of time, such bacteria have become resistant to these antibiotics, resulting in prolonged bacterial infection and diseases. Resistance in bacteria is caused generally by means of self-medication, genetic variations, or mutations in bacteria and also by phenotypic variation such as β-lactams. As antibiotics are specific to their targets, bacteria secrete certain enzymes to cleave chemical bonds within antibiotic structure. Furthermore, alteration in membrane permeability, antibiotic target modifications in bacteria, and resistant gene transfer to next generations also cause resistance to antibiotics and, hence, bacteria such as Staphylococcus aureus and Neisseria gonorrhea, etc. have become resistant and cause lethal diseases in human beings...
eBook - ePub- José-Luis Capelo-Martínez, Gilberto Igrejas, José-Luis Capelo-Martínez, Gilberto Igrejas(Authors)
- 2019(Publication Date)
- Wiley(Publisher)
...The agents that entered the full development since 1995 were mostly from the already known classes of antibiotics (Bush2012).Bacteria's ability to respond to stresses and challenges by toxic compounds, which include antibiotics, results in resistance to therapies. Defense mechanisms can be developed from the presence of intrinsic genes in their genome that could generate a resistance phenotype and from the mutations in chromosomal genes (Davies and Davies2010), as well as due to horizontal gene transfer (HGT) responsible for increased propagation ofresistance through bacterial populations (Nakamura et al.2004). More often than not, resistance induced by an antibiotic leads to decrease of efficacy of other structurally unrelated antibiotics, resulting in the development of multidrug‐resistant (MDR) bacterial strains. The specter of untreatable infections is becoming a real threat as the resistance was recently observed against the drugs of last resort, such as vancomycin and colistin (Boucher et al.2009; Liu et al.2016), and the demand for new antibiotic therapies is critical.In the era of the antibiotic resistance, the development of the new antibiotics focuses on the new or unexplored targets present in resistant strains, while the alternative strategies include developing agents that target the mechanisms responsible for antibiotic resistance and failure of infection treatments(Schillaci et al.2017)...
- 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 - ePubGenetics 101
From Chromosomes and the Double Helix to Cloning and DNA Tests, Everything You Need to Know about Genes
- Beth Skwarecki(Author)
- 2018(Publication Date)
- Adams Media(Publisher)
...Before long, the antibiotic resistance gene becomes a popular thing: if antibiotics are around, antibiotic-resistant bacteria will flourish while susceptible germs will die. The same is true of antibiotic resistance genes on the main bacterial chromosome. If you have a gene that gives you resistance, you’ll be able to survive longer and have more children. In many cases, antibiotic resistance genes don’t give perfect protection: if you’re totally swamped with antibiotics, they could still kill you anyway. That’s why, if you get a prescription of antibiotics from your doctor, it probably comes with a sticker warning you that you must finish the entire course of antibiotics. The idea there is to keep up a large concentration of antibiotics in your body until all the susceptible bacteria are killed. But resistance flourishes anyway. If you had a particularly tough bacterium in your body, it might be able to survive even the regular dose of antibiotics. And when you stop taking the antibiotics, that bacterium might even be able to gift its plasmid to other bacteria that come to infect you later. Even our harmless gut bacteria can get in on this gift exchange: after you take antibiotics, you’re likely to end up with some antibiotic-resistant bacteria in your gut, and they can give plasmids to other, more harmful bacteria later on. Because antibiotic-resistant bacteria are more likely to survive over time, the antibiotics represent a selection pressure that drives evolution. The process by which susceptible germs die off and resistant ones flourish is called natural selection. To prevent antibiotic resistance from becoming more common, finishing our prescriptions isn’t enough. It’s also important that doctors only prescribe antibiotics when they are absolutely necessary. That’s why your doctor might decline to give you antibiotics for a cold or flu: those are both viral illnesses, and antibiotics don’t do anything to kill viruses...
eBook - ePubOne Health
People, Animals, and the Environment
- Ronald M. Atlas, Stanley Maloy, Ronald M. Atlas, Stanley Maloy(Authors)
- 2014(Publication Date)
- ASM Press(Publisher)
...As has been oft described, pathogens have a number of responses to antibiotic exposure. For one thing, mutations to resistance may come at considerable cost in energy and interfere with interactions within microbial communities: a resistant pathogen is often at a disadvantage in the absence of antibiotic (22). This may seem like a state of quasi-dependence, and antibiotic contamination contributes to the maintenance of the organism(s). WHAT NEXT? Finally, the burning question: what can be done to control/prevent antibiotic resistance development? There have been countless meeting resolutions, proposals, recommendations, workshops, government statements, and occasionally laws to reduce the threat of antibiotic resistance over the last half century. As an example, see reference 23. The threat is recognized with continuing urgency but diminishing resolve, and the problem is still growing; a return to a pre-antibiotic state is not just a bad dream. From the standpoint of microbes this is not surprising; we are inhabiting “their” planet. As the late Joshua Lederberg said, “In this conflict there is no guarantee that humans will be the survivors.” Determined actions should (must?) be taken, but they are hard to implement given our dependence on antibiotics and related drugs. 1. The use of antibiotics must be strictly controlled using all legal steps necessary. They should be restricted to prescription-only use with absolutely no over-the-counter sales anywhere. Their use should be exclusively human (this applies to closely related compounds). This is a near impossible demand and will almost certainly lead to a black market situation. The international community puts a lot of effort into controlling nuclear weapons; why not antibiotics? 2. Novel antimicrobial agents must be sought and found by increasing discovery research at all levels, supported by governmental policies. There is an enormous wealth of bioactive small molecules waiting to be discovered (24)...
eBook - ePubBacterial Pathogenesis
A Molecular Approach
- Brenda A. Wilson, Malcolm Winkler, Brian T. Ho(Authors)
- 2019(Publication Date)
- ASM Press(Publisher)
...Unfortunately, because few new antibiotics against emerging multidrug-resistant bacterial pathogens, such as multidrug-resistant Mycobacterium tuberculosis (the causative agent of tuberculosis), are available, older antibiotics that were not widely used earlier because of serious side effects are increasingly being used as treatments of last resort. However, this strategy only makes treatment that much more difficult, because the long-term regimens required to treat tuberculosis, which involve the simultaneous administration of several different antibiotics, are tolerated by patients even less well than before. All of these factors must be considered when choosing an effective therapeutic compound. In the remainder of this chapter, the focus will be on the effects of antimicrobials on the bacteria themselves, but these traits of antimicrobials and of the bacteria they target are only part of the treatment story. In the next chapter, we will discuss how bacteria become resistant to these antimicrobials. Antiseptics and Disinfectants Antiseptics and disinfectants, like antibiotics, are chemicals that kill or inhibit the growth of bacteria and other microorganisms. Most antiseptics and disinfectants are bactericidal. Most are also effective against many other types of disease-causing microbes such as viruses, fungi, and protozoa. This broad coverage has a drawback, however, because the chemicals used as antiseptics and disinfectants are often too toxic for internal use in humans and animals...
