Antibiotic - Definition, Types, Side Effects, Discovery, Do's & Don'ts

There are two ways of antibiotic synthesis; 1. Antibiotic production by  bacterial fermentation process and 2. Chemically synthesis of antibiotics.

A true antibiotic was discovered by Alexander Fleming and it is named as penicillin.

Selman Abraham Waksman is the father of antibiotics, because he discovered 20 most important antibiotics including streptomycin and all antibiotics are synthesized by natural process.

The word antibiotics' name suggests ‘Anti’ means against and ‘Biotic’ means life.

Antibiotics affect bateria by different ways, such as Inhibition of cell wall synthesis, Change in cell membrane potential, Inhibits protein synthesis process, Inhibits nucleic acid synthesis and Inhibits metabolic pathway of bacteria.

Antibiotics can impact nutrient metabolism in several ways. They can alter the gut microbiome, which plays a crucial role in the breakdown and absorption of nutrients. Some antibiotics can interfere with the absorption of specific nutrients; for example, tetracyclines can bind to calcium, reducing its absorption. Antibiotics can also affect the body's ability to synthesize certain vitamins that are normally produced by gut bacteria. Additionally, by altering the gut flora, antibiotics can influence the metabolism of carbohydrates, potentially affecting blood sugar levels.

Common side effects of antibiotics include gastrointestinal disturbances (nausea, vomiting, diarrhea), fungal infections (like yeast infections), and allergic reactions (rashes, itching). These often occur because antibiotics can disrupt the normal balance of bacteria in the body or trigger immune responses. More severe side effects, though rarer, can include kidney or liver damage with certain antibiotics.

Antibiotic-associated diarrhea occurs when antibiotics disrupt the normal balance of bacteria in the gut. By killing both harmful and beneficial bacteria, antibiotics can allow opportunistic pathogens to overgrow or cause changes in metabolism of carbohydrates, leading to diarrhea. In severe cases, it can lead to a Clostridium difficile infection, which can be life-threatening.

Antibiotics can significantly alter the human microbiome, the community of microorganisms living in and on our bodies. While targeting harmful bacteria, antibiotics also kill beneficial bacteria, potentially leading to imbalances in the microbiome. This can affect various bodily functions, including digestion, immune response, and even mood regulation. The impact can be long-lasting, with some studies showing microbiome changes persisting for months after antibiotic treatment.

Antibiotics are prescription-only medications for several reasons: 1) To ensure they're used only when necessary, reducing the risk of antibiotic resistance. 2) To match the correct antibiotic to the specific infection, as different antibiotics target different bacteria. 3) To monitor for potential side effects or interactions with other medications. 4) To ensure the correct dosage and duration of treatment, which can vary based on the infection and patient characteristics.

Antibiotic resistance occurs when bacteria evolve to survive exposure to antibiotics that previously could kill or inhibit them. It develops through natural selection – bacteria with genetic mutations that allow them to survive antibiotics reproduce, passing on their resistant traits. Overuse and misuse of antibiotics accelerate this process by creating more opportunities for resistant bacteria to thrive.

Penicillin was discovered accidentally by Alexander Fleming in 1928. He noticed that mold contaminating one of his petri dishes had created a bacteria-free zone around it. This mold, later identified as Penicillium notatum, was producing a substance (penicillin) that killed the bacteria. This serendipitous observation led to the development of the first antibiotic.

Biofilms are communities of microorganisms that adhere to surfaces and secrete a protective extracellular matrix. They play a significant role in antibiotic resistance by creating a physical barrier that antibiotics struggle to penetrate. Within biofilms, bacteria can also enter a dormant state, making them less susceptible to antibiotics that target actively growing cells. Additionally, the close proximity of bacteria in biofilms facilitates the exchange of genetic material, potentially spreading resistance genes. Biofilms are particularly problematic in medical device infections and chronic wounds.

Antibiotics can significantly disrupt the oral microbiome, which plays important roles in oral health, including preventing the overgrowth of pathogenic bacteria. This disruption can lead to an imbalance favoring the growth of opportunistic pathogens, potentially resulting in oral health issues like thrush (a fungal infection) or an increased risk of dental caries. The

Bactericidal antibiotics kill bacteria directly, while bacteriostatic antibiotics inhibit bacterial growth without necessarily killing them. Bactericidal antibiotics, like penicillin, often target cell wall synthesis or DNA replication. Bacteriostatic antibiotics, such as tetracyclines, typically interfere with protein synthesis. In practice, this distinction isn't absolute, as the effect can depend on the antibiotic concentration and the specific bacteria involved.

Beta-lactam antibiotics, which include penicillins and cephalosporins, work by interfering with bacterial cell wall synthesis. They contain a beta-lactam ring that binds to and inhibits enzymes (called penicillin-binding proteins) necessary for building the bacterial cell wall. Without a properly formed cell wall, bacteria become structurally weak and eventually burst due to osmotic pressure. This mechanism is effective against many bacteria but useless against those without cell walls, like mycoplasma.

Antibiotics are medications that fight bacterial infections. They work by either killing bacteria directly or stopping their growth and reproduction. Antibiotics target specific structures or processes in bacterial cells that are different from human cells, allowing them to selectively harm bacteria without damaging our own cells.

The gut-brain axis is the bidirectional communication system between the gastrointestinal tract and the central nervous system. Antibiotics can disrupt this axis by altering the gut microbiome, which plays a crucial role in this communication. Changes in the microbiome can affect the production of neurotransmitters, immune responses, and the integrity of the gut barrier. This disruption has been linked to changes in mood, behavior, and cognitive function, highlighting the far-reaching effects of antibiotics beyond just fighting infections.

Bacteriophages are viruses that infect and kill bacteria. They're being researched as an alternative or complement to antibiotics, especially for treating antibiotic-resistant infections. Unlike broad-spectrum antibiotics, phages are highly specific, targeting only certain bacterial species or strains. This specificity means they're less likely to disrupt the normal microbiome. Phage therapy faces challenges in regulatory approval and production, but it represents a promising avenue in the fight against antibiotic resistance.

Antibiotic production and use have significant environmental impacts. Manufacturing processes can release antibiotics into water systems, contributing to environmental contamination. Antibiotics excreted by humans and animals enter sewage systems and eventually water bodies, affecting aquatic ecosystems. This environmental presence of antibiotics can lead to the development of antibiotic-resistant bacteria in nature, which can then spread to humans and animals. Additionally, antibiotics in the environment can disrupt natural microbial communities, potentially affecting ecosystem functions.

Developing new antibiotics faces several challenges: 1) Scientific difficulty in finding new mechanisms to target bacteria without harming human cells. 2) Economic disincentives, as new antibiotics are often held in reserve and used sparingly to prevent resistance, reducing profitability. 3) Regulatory hurdles in clinical trials, as proving superiority over existing antibiotics can be challenging. 4) The rapid development of resistance, which can make new antibiotics obsolete quickly. These factors have led to a significant slowdown in new antibiotic development in recent decades.

Completing the full course of antibiotics is crucial to ensure all harmful bacteria are eliminated. Stopping early, even if symptoms improve, can leave some hardier bacteria alive. These surviving bacteria may be partially resistant to the antibiotic and can multiply, potentially leading to a recurrence of the infection with antibiotic-resistant bacteria. This practice helps prevent the development and spread of antibiotic resistance.

Probiotics are beneficial bacteria that can help restore the balance of the gut microbiome often disrupted by antibiotics. Taking probiotics during or after antibiotic treatment may help reduce side effects like diarrhea and prevent opportunistic infections like Clostridium difficile. However, it's important to space out probiotic and antibiotic doses to ensure the antibiotics don't kill the probiotic bacteria.

Antibiotic stewardship refers to coordinated programs and interventions designed to improve and measure the appropriate use of antibiotics. It's important because it helps preserve the effectiveness of existing antibiotics, slows the development of antibiotic resistance, reduces healthcare costs, and improves patient outcomes. Stewardship programs typically involve guidelines for prescribing, monitoring antibiotic use, and educating healthcare providers and patients about proper antibiotic use.

Antibiotics can interact with other medications in various ways. Some antibiotics can affect the metabolism of other drugs, either increasing or decreasing their effectiveness. For example, certain antibiotics can reduce the effectiveness of oral contraceptives. Others may enhance the effects of blood thinners, increasing the risk of bleeding. Some antibiotics can also interact with alcohol, causing nausea and vomiting. It's crucial to inform healthcare providers about all medications being taken to avoid potentially harmful interactions.

Antibiotics can have both positive and negative effects on wound healing. They can prevent or treat infections that would otherwise impede healing. However, some antibiotics, particularly at high doses, can interfere with the proliferation of cells involved in wound repair, potentially slowing the healing process. Additionally, by altering the microbiome of the wound, antibiotics can affect the delicate balance of inflammation and repair necessary for optimal healing. The net effect depends on the specific antibiotic, its dosage, and the nature of the wound.

Broad-spectrum antibiotics are those that are effective against a wide range of bacterial types, including both gram-positive and gram-negative bacteria. They target cellular processes common to many bacteria, making them useful for treating infections when the specific pathogen is unknown. However, their wide-ranging action also means they're more likely to affect beneficial bacteria in the body.

Narrow-spectrum antibiotics are effective against specific types of bacteria, often either gram-positive or gram-negative. They target unique features of these bacterial groups, making them more selective in their action. While they may be less versatile than broad-spectrum antibiotics, they're less likely to disturb the body's normal bacterial flora or contribute to antibiotic resistance.

The generational classification of antibiotics, particularly in cephalosporins, refers to their spectrum of activity and resistance to beta-lactamases. First-generation antibiotics typically have a narrower spectrum, mainly effective against gram-positive bacteria. Second-generation antibiotics have an expanded gram-negative coverage while maintaining gram-positive activity. Third-generation antibiotics have even broader gram-negative coverage and increased stability against beta-lactamases. Each subsequent generation often trades some gram-positive potency for improved gram-negative coverage and resistance to antibiotic-degrading enzymes.

Antibiotics are ineffective against viruses because viruses have a fundamentally different structure and life cycle compared to bacteria. Viruses lack many of the cellular components that antibiotics target in bacteria, such as cell walls or protein-making machinery. Additionally, viruses replicate inside our own cells, making it difficult to target them without harming human cells.

Efflux pumps are protein structures in bacterial cell membranes that can expel antibiotics from the cell, contributing to antibiotic resistance. These pumps can recognize and export various antibiotics, reducing their concentration inside the bacterial cell to ineffective levels. Some bacteria can overexpress these pumps in response to antibiotic exposure, quickly developing resistance. Understanding and targeting efflux pumps is an important area of research in combating antibiotic resistance.

Antibiotic cycling, also known as antibiotic rotation, is a strategy used in hospitals to prevent the development of antibiotic resistance. It involves periodically changing the primary antibiotics used in a healthcare setting. The theory is that by regularly switching between different classes of antibiotics, bacteria have less time to develop resistance to any one type. However, the effectiveness of this approach is debated, as resistance mechanisms can persist even when an antibiotic is not in use, and cross-resistance between antibiotics can occur.

The post-antibiotic era refers to a potential future where common infections become untreatable due to widespread antibiotic resistance. In this scenario, routine medical procedures could become high-risk, and minor infections could once again become life-threatening. This concept underscores the urgency of addressing antibiotic resistance through better stewardship, development of new antibiotics, and exploration of alternative therapies. It highlights the need to preserve the effectiveness of our current antibiotics while seeking new solutions.

Antibiotic prophylaxis is the preventive use of antibiotics before certain medical procedures or in specific situations to prevent bacterial infections. It's commonly used before surgeries, especially those involving implants or in areas with high infection risk. It's also used for people with certain heart conditions before dental procedures to prevent infective endocarditis. The goal is to prevent infections before they start in high-risk situations.

Topical antibiotics are applied directly to the skin or mucous membranes to treat localized infections. They work at the site of application and generally have minimal systemic absorption. Systemic antibiotics, on the other hand, are taken orally or intravenously and circulate throughout the body in the bloodstream. Topical antibiotics are typically used for minor skin infections or to prevent infections in wounds, while systemic antibiotics are used for more serious or widespread infections.

Antibiotic synergy occurs when the combined effect of two or more antibiotics is greater than the sum of their individual effects. This approach is used in certain situations, such as treating severe or resistant infections, or when a broader spectrum of activity is needed. For example, combining a cell wall inhibitor like ampicillin with an aminoglycoside can enhance bacterial killing. However, antibiotic combinations must be chosen carefully to avoid antagonistic effects or increased toxicity.

Antibiotics are used in agriculture to treat infections in livestock, prevent disease outbreaks, and promote growth. However, this practice contributes significantly to the development of antibiotic-resistant bacteria, which can spread to humans through food products or environmental contamination. This agricultural use of antibiotics is a major concern in human health, as it reduces the effectiveness of antibiotics in treating human infections and accelerates the global antibiotic resistance crisis.

Some antibiotics are safe during pregnancy, while others can pose risks to the developing fetus. Safe antibiotics, like penicillins and cephalosporins, don't cross the placenta easily and haven't shown adverse effects. However, certain antibiotics, such as tetracyclines, can affect fetal bone and tooth development, while others like fluoroquinolones may impact cartilage formation. The potential risks must be weighed against the need to treat maternal infections, which can also harm the fetus if left untreated.

Early exposure to antibiotics can alter the development of a child's immune system by disrupting the normal colonization of beneficial bacteria. This disruption may increase the risk of allergies, asthma, and other immune-related disorders later in life. The developing immune system relies on exposure to a diverse microbiome to "learn" how to respond appropriately to various stimuli. Overuse of antibiotics in early childhood may interfere with this process, potentially leading to immune dysregulation.

Antibiotic exposure in infancy can significantly alter the developing microbiome. The infant microbiome plays a crucial role in the maturation of the immune system, metabolism, and even brain development. Antibiotics can reduce the diversity of the microbiome and delay the establishment of beneficial bacteria. This disruption has been associated with increased risks of allergies, asthma, obesity, and other health issues later in life. The impact is particularly significant in the first few years of life when the microbiome is most malleable.