Types of Antibiotics

Penicillins kill bacteria by breaking down their cell walls, leading to bacterial death. Common examples are Amoxicillin, Penicillin V and Penicillin G.

Quinolones inhibit the DNA replication enzymes gyrase and topoisomerase IV. Common examples include Ciprofloxacin, Levofloxacin and Moxifloxacin.

These antibiotics, like Penicillins and Cephalosporins, bind to PBPs (penicillin-binding proteins) and inhibit the final step in the synthesis of peptidoglycan, a component of the bacterial cell wall, leading to bacterial death.

Penicillins are the type of antibiotics used to treat Strep throat, Pneumonia, and Otitis media. They work by inhibiting bacterial cell wall synthesis, leading to bacterial incapacity to survive.

Macrolides are commonly prescribed for Community-acquired pneumonia, Uncomplicated skin infections, Pertussis (whooping cough), Diphtheria, and Chlamydia. They inhibit protein synthesis in bacteria, impacting their capability to reproduce.

Quinolones are used for treating Urinary tract, Respiratory tract, Gastrointestinal, Bone and joint, and Skin and soft tissue infections. Tetracyclines manage Acne, Rosacea, Lyme disease, Chlamydia, Rickettsial infections and Anthrax. Aminoglycosides are used to treat Tuberculosis (as a second-line treatment), Sepsis, Respiratory tract infections, Complicated urinary tract infections, and Pelvic inflammatory disease.

Antibiotics primarily work by killing bacteria (bactericidal antibiotics) or by inhibiting bacterial growth (bacteriostatic antibiotics).

Penicillins and cephalosporins inhibit cell wall synthesis by binding to penicillin-binding proteins (PBPs), blocking the cross-linking of peptidoglycan chains, leading to weaker cell walls that burst due to osmotic pressure.

Macrolides inhibit bacterial growth (bacteriostatic) by binding to the 50S subunit of the bacterial ribosome, disrupting protein synthesis, preventing bacterial reproduction, and increasing their susceptibility to the immune system.

These include the patient's age, weight, health status, possible bacterial resistance, allergic history, side-effects, and potential interactions with other drugs. Dosage, duration of treatment, cost, and availability of the drug are also considered.

Quinolones work by inhibiting two essential bacterial enzymes, DNA gyrase and topoisomerase IV. This action prevents the bacteria from synthesising DNA and reproducing.

Both Tetracyclines and Aminoglycosides inhibit protein synthesis in bacterial cells. Tetracyclines block the attachment of aminoacyl-tRNA to the mRNA-ribosome complex. Conversely, Aminoglycosides result in mRNA misreading, generating abnormal, non-functional proteins.

Glycopeptide Antibiotics have a complex chemical structure which includes sugars and peptide elements (a chain of amino acids).

They have large complex structures, play a crucial role in inhibiting bacterial membrane function, and are effective against Gram-positive bacteria.

The discovery of the mechanism through which these antibiotics work by blocking bacterial cell wall synthesis.

Glycopeptide Antibiotics are created by the actinobacteria class and work by targeting the cell walls of bacteria.

The main classifications of Glycopeptide Antibiotics are based on their structure and their mechanism of action.

Vancomycin targets cross-linking (transpeptidation), Teicoplanin targets carbohydrate backbone formation (transglycosylation), and Oritavancin targets cross-linking with enhanced affinity.

Natural Glycopeptides are produced by certain bacteria species, Semi-synthetic Glycopeptides are chemically modified natural ones, and Synthetic Glycopeptides are fully synthetically made in laboratories.

Vancomycin inhibits cell wall synthesis in bacteria by binding to the D-Ala-D-Ala terminal of the peptidoglycan precursor, blocking transpeptidation.

Glycopeptide Antibiotics function by obstructing the construction of bacterial cell walls, specifically by interfering with the cross-linking of the peptidoglycan layer.

They bind tightly to the D-Ala-D-Ala moieties on the cell wall precursors, impeding the enzyme transpeptidase from cross-linking peptidoglycan chains necessary for cell wall stability.

Gram-positive bacteria lack the protective outer membrane which Gram-negative bacteria possess, making them more susceptible to Glycopeptide Antibiotics.

They are used for treating severe Gram-positive bacterial infections, MRSA infections, and endocarditis. They also provide prophylaxis in neutropenic patients and for surgeries involving implanted prosthetic materials.

Neomycin is an aminoglycoside antibiotic derived from the bacterium Streptomyces fradiae. It is important in Microbiology due to its wide antimicrobial action against a broad spectrum of bacterial infections, particularly those caused by gram-negative bacteria.

Neomycin works by binding to the 30S subunit of the bacterial ribosome, interfering with protein synthesis. This blocks the bacteria's ability to produce the proteins it needs to survive and replicate.

Neomycin is poorly absorbed orally, primarily affecting the gastrointestinal tract. Topically, it's absorbed at low levels unless applied to large or open wounds. As eye drops, the absorption is minimal, with most of it remaining in the eye's outer tissues.

Neomycin belongs to a class of antibiotics called Aminoglycosides. It's used for treating bacterial infections, including skin infections, wound infections, dermatological conditions, and ocular infections. It's also used as a prophylactic agent during surgeries to prevent infections.

Neomycin plays a role in controlling communicable diseases by treating pathogens in the gut and on the skin. For instance, it helps control Hepatic Encephalopathy by reducing the production of ammonia in the gut, prevents cholera by killing off the cholera-causing bacteria, and curbs skin infections like Impetigo by eliminating the responsible bacteria.

Consulting with a healthcare provider is essential before starting a Neomycin treatment to prevent antibiotic resistance, which is a serious global health concern. Misuse of antibiotics can lead to bacteria becoming resistant to them, rendering the medications ineffective.

Neomycin can cause skin reactions, neurological symptoms, audiological problems, and nephrotoxicity. Typical symptoms include skin irritation, dizziness, a feeling of fullness in the ears, and reduced urinary output.

If you experience side effects, you should stop using Neomycin, seek medical advice, your doctor may adjust your dosage, treat the symptoms with over-the-counter medications, hydrate, and monitor your symptoms during treatment.

Prolonged or high dosage use of Neomycin can cause neurological symptoms, audiological problems, and nephrotoxicity. Symptoms include dizziness, ringing in the ears, and reduced urinary output.

Genticin is used to treat several types of bacterial infections, especially those caused by Gram-negative organisms. It is usually administered intravenously or intramuscularly.

Neomycin is prescribed for treating bacterial infections affecting the intestines and minor skin infections. It is typically used topically, and oral intake is less common due to potential side effects.

Genticin can cause kidney damage and hearing loss, but these occur rarely. Neomycin, when taken orally, poses a higher risk of kidney damage and could lead to hearing impairment.

Neomycin, an aminoglycoside antibiotic, fights bacterial infections by binding to the bacterial ribosome's 30S subunit, thereby obstructing protein synthesis and leading to bacterial cell death.

Bacteria can develop resistance to Neomycin primarily through mutation in the binding site on the 30S ribosome, preventing Neomycin from attaching and inhibiting protein synthesis, or by producing enzymes that modify and inactivate Neomycin.

Potential future applications of Neomycin include genetic engineering for modulating gene expression, 'smart' Neomycin therapeutics using advanced drug delivery systems, and as an adjuvant for enhancing the immune response in vaccines.

Quinolones are a class of synthetic broad-spectrum antibiotics that kill bacteria by interfering with the enzyme DNA gyrase, which bacteria require for replication. They have a specific chemical structure called the "quinolone core". They are categorised into generations based on their time of discovery and development.

An older quinolone is nalidixic acid, mainly effective against gram-negative bacteria, while a newer or advanced quinolone is ciprofloxacin, effective against a wider variety of bacteria, including gram-positive ones.

Quinolones trace back to 1962 with the discovery of nalidixic acid. By 1980, fluoroquinolones, a more advanced subclass, were introduced. Despite concerns about antibiotic resistance, quinolones remain a crucial part of our antibiotic arsenal today. The discovery of nalidixic acid was somewhat accidental from a by-product of chloroquine synthesis.

Quinolones have a unique core structure called the "quinolone core". This core is a bicyclic system containing a pyridone ring and is what differentiates quinolones from other antibiotics.

The four crucial positions on the quinolone core where substituents exist are C-3, C-7, C-6, and C-8. They influence the drug's antibacterial activity, spectrum of activity, toxicity, efficacy against resistance mechanisms, and pharmacokinetic profile.

The main difference lies in their molecular structures. Fluoroquinolones are a subclass of quinolones with a fluorine atom added to the C-6 position of the quinolone core structure. This addition improves antibacterial spectrum, pharmacokinetics, and resistance.

Quinolones work by inhibiting two important bacterial enzymes: DNA gyrase and topoisomerase IV. This action interrupts DNA replication in bacteria, leading to bacterial cell death.

DNA gyrase introduces negative supercoils (or relaxes positive supercoils) into the DNA molecule essential for DNA replication and transcription. Topoisomerase IV segregates daughter DNA molecules following DNA replication.

Nalidixic Acid is primarily effective against Gram-negative bacteria. Ciprofloxacin is effective against a wide array of bacteria. Levofloxacin targets Gram-positive bacteria. Moxifloxacin has improved activity against anaerobes and Gram-positive organisms.

Nalidixic Acid targets Gram-negative bacteria and treats urinary tract infections. Ciprofloxacin is a broad-spectrum antibiotic for treating infections of skin, lungs, airways, bones, and joints. Levofloxacin targets Gram-positive bacteria while Moxifloxacin has improved activity against Gram-positive organisms and anaerobes. Trovafloxacin has a broad-spectrum activity and is used for complicated intra-abdominal infections and bacterial meningitis.

Quinolones such as nalidixic acid and ciprofloxacin manage urinary tract infections. Advanced quinolones like levofloxacin and moxifloxacin treat respiratory tract infections. For skin infections, quinolones like ciprofloxacin and levofloxacin are used. Trovafloxacin is used for intra-abdominal infections and bacterial meningitis.