Introduction of antibiotics 💊💉
A substance that inhibits the growth of microorganisms or kills them and causes no harm to the host cell called an antimicrobial agent or antibiotic drugs. The antimicrobial agent is of, natural, semi-synthetic, or synthetic origin.
Alexander Fleming was a British investigator who discovered penicillin. In 1928 Fleming describe the enzyme lysozyme. He observed that the Petri dish culture of staphylococci had become contaminated with green mold and that the bacteria were disappearing as the mold grew over the plate. The mold isolated was identified as Penicillium and found that the broth contained an active principle with antibacterial characters.
Rene Dubos in 1939 indicated that soil bacteria could produce anti-bacterial chemicals like Fleming's penicillin. a group of Oxford University, led by British pathologist, Howard Florey and German biochemist, Ernst Boris Chain, reisolated penicillin and carried out careful trials with the highly purified samples. American pharmaceutical companies developed technology for the large-scale production of penicillin.
Fleming, Florey, and Chain received Nobel Prize in 1945 for the development and discovery of penicillin. penicillin is the first antibiotic.
What is chemotherapy:
Without damaging the host cells, chemical compounds or drugs uses for the treatment of infectious diseases known as chemotherapy.
The main types of antimicrobial drugs
Antibiotics are chemical substances, produced by microorganisms, having the properties of inhibiting the growth or destroying the microorganism.
Antibacterial agents, It is synthesized in the laboratory.
Semisynthetic antibiotics. Many antimicrobial agents have a chemical structure is derived from the microbial source but its chemical structure is then modified by attaching different chemical moieties.
Explain the mode of action of antimicrobial drugs
Bacteriostatic | Bactericidal | Fungistatic | Fungicidal |
Arrest the growth and replication of the bacteria thus break the spread of infection. or the drugs which prevent the growth of microorganisms called Bacteriostatic. | The bactericidal drug, kill, or irreversible damage the multiplying bacteria. or the drugs that destroy the microorganisms are called bactericidal drugs. | Arrest the growth and replication of the fungi thus break the spread of infection | The fungicidal drug, kill, or irreversible damage the multiplying fungi. |
Mechanism of action of antibiotics drugs: Antibiotics drugs act as.
Inhibit bacterial cell wall synthesis, eg. → | Penicillins | Cephalosporins | Monobactams | Carbapenems |
Alter of cell membrane integrity, eg.→ | Polymixins | Amphotericin-B | Azoles | Chlorhexidine |
Inhibit of ribosome protein synthesis, eg.→ | Aminoglycosides | Tetracyclines | Macrolides | Clindamycin |
Suppression of DNA synthesis, eg.→ | Sulfonamides | Trimethoprim |
Types of antimicrobial drugs Spectrum 💊
According to the spectrum of activity, antimicrobial drugs are grouped as,
- Narrow spectrum drugs,
- Broad-spectrum drugs,
- Extended-spectrum drugs.
Narrow spectrum- It is selectively effective either on gram+ve or gram - ve bacteria or certain fungi, yeast, or active against a limited group of pathogens are called narrow-spectrum antimicrobial drugs. such as benzylpenicillin, erythromycin, vancomycin.
Broad-spectrum - It is effective in numerous pathogens such as gram +ve bacteria, gram - ve bacteria, viruses, rickettsiae, or a wide range of pathogens, which are called broad-spectrum antimicrobial drugs. Like tetracycline, chloramphenicol, streptomycin, amoxicillin.
Extended-spectrum drugs - They are effective against gram-positive organisms and some gram-negative pathogens.
👉 Antibiotics are effective against gram-positive bacteria such as penicillin, ampicillin, etc.
👉 Antibiotics are effective against gram-negative bacteria such as streptomycin, gentamicin, etc.
👉 Antibiotics are effective against both gram +ve and gram-negative bacteria, etc.
Penicillins:
Discovered → Alexander Fleming 1929.
Origin → mold Penicillium notatum and Penicillium chrysogenum.
MOA → bactericidal.
Adverse effects → Anaphylactic shock, idiosyncrasy, allergy reaction.
Uses → Upper respiratory infection, Urinary tract infection, rheumatic fever
Classification | Penicillin drugs |
Natural penicillin | Penicillin- G (Benzyl Penicillin) |
Piperacillin | |
Broad-spectrum penicillin | Ampicillin, Amoxycillin, Ampicillin with Sulbactam Sodium |
Penicillinase resistant penicillin | Cloxacillin |
Penicillin active against pseudomonas | Carbenicillin. |
Aminoglycosides antibiotics
Aminoglycosides are derived from the species of Streptomycin. Gentamicin is the first drug to be given for infections by gram-negative bacteria. Neomycin is now used as topical antibiotics for eye bacterial conjunctivitis or gram-negative infection.
Uses of aminoglycosides antibiotics drug:
It is very effective against gram-negative bacteria.
- Bacteraemias,
- Septicaemias,
- Respiratory tract infection,
- Bone and joint infection,
- CNS,
- Skin and soft tissue infection,
- intraabdominal infection,
- Burns,
- Postoperative infection.
Aminoglycosides | Drugs |
Amikacin, | Tobramycin sulfate |
Neomycin, | sisomicin, |
Tobramycin | Streptomycin |
Netilmicin, | |
Kanamycin | |
Gentamicin, |
Carbacephems antibiotics
Loracarbef.
Carbapenem:
Carbapenem is a synthetic Beta-Lactum antibiotic. It is given by injection (by parenteral route) into the body. for uses of,
- Pneumonia,
- Intra-abdominal infection,
- Gynecological infection,
- Skin infection.
- Meningitis,
- Septicemia
- Febrile neutropenia.
Carbapenem | Drugs |
Meropenem Trihydrate | Faropenem, |
Imipenem with Cilastatin | |
Ertapenem, | |
Doripenem | |
Panipenem. | |
Biapenem, |
Cephalosporins antibiotics
Discover → In 1960.
Isolated → fungus, Cephalosporinium acremonium (Cephalosporins), and Streptomyces lactamdurans (cefamycin).
Cephalosporium. Now many semi-synthetic drugs are developed from it.
cephalosporins are an alternative to penicillin.
Uses:
- Staphylococcal boils or wounds,
- Streptococci,
- Bacterial pneumonia,
- Urinary tract infections by gram-negative bacteria.
Classification | Cefalosporin drugs |
1st generation cefalosporin | Cefalexin, Cefadroxil,Cefradine, Cefazolin, |
2nd generation cefalosporin | Cefaclor, Cefuroxime. Cefprozil. Cefotetan, Cefamandole, Cefoxitin |
3rd generation cefalosporin | Cefixime, Cefpodoxime, Ceftibuten, Cefdinir, Cefditoren, Ceftolozane, Cefoperazone, Ceftriaxone, Cefotaxime, Ceftazidime, Ceftizoxime. |
4th generation cefalosporin | Cefepime, Cefpirome, Cefozopran |
5th generation cefalosporin | Ceftaroline, Ceftobiorole. |
Combination with other medicine
Cephalosporins w/β- lactamase inhibitors:
- Ceftazidime + Avibactam,
- Ceftolozane + Tazobatam,
- Cefoperazone + Sulbatam,
- Cefoperazone + Tazobactam,
- Ceftrixone + Sulbactam,
- cefotaxime + sulbactam,
- Cefuroxime + Clavulanic acid,
- Cefixime + Clavulanic acid,
- Ceftazidime + Tazobactam,
- Ceftrixone + Tazobactam.
Chloramphenicol antibiotics
Chloramphenicol is the first broad-spectrum antibiotic. It was isolated in 1947 by Ehrlich, Burkholder, and Gotlieb. It inhibits a wide variety of Gram-positive and gram-negative bacteria. And rickettsiae and fungi. it inhibits protein synthesis at the 50S ribosomal level. it is a bacteriostatic drug.
Uses:
- Typhoid fever,
- Meningitis,
- Urinary tract infection,
- ENT infection,
- intracranial bacteria infection.
- Chloramphenicol.
Ketolides antibiotics
Ketolides approved for the first time in 2004. telithromycin is used for the treatment of bronchitis, sinusitis, and pharyngitis.
- Telithromycin
Lincosamides antibiotics
it is used in treating a serious infection like a liver abscess, lung bases, bone, and joint infection.
- Lincomycin,
- Clindamycin.
Oxazolidinones antibiotics
It is an antibiotic medicine, used when there is a bacterial infection in the body. This antibiotic medicine is given in the case of the following disease,
Uses of Oxazolidinones
- Pneumonia infection,
- Skin infection,
- febrile neutropenia septicemia,
- Endocarditis,
- Osteomyelitis surgical prophylaxis.
Oxazolidinones drugs:
- Linezolid,
- Tedizolid,
- Radezolide,
- Torezolide.
Macrolides antibiotics
macrolides drugs are a Bacteriostatic and broad spectrum of activity. it is used against gram-negative bacteria and gram-positive bacteria. macrolides inhibit the protein synthesis of the bacteria. it is used.
Uses of Macrolides drugs:
- Upper respiratory tract infection,
- Acute pneumonia,
- Vaginitis infection,
- wound and burn infection,
- Infected eczema,
- Acne vulgaris,
- Skin infection.
macrolides | drugs |
Azithromycin, | Clarithromycin, |
Roxithromycin, | Polymyxin B |
Aztreonam | Telithromycin |
Teicoplanin | Vancomycin |
Colistimethate | Erythromycin, |
Spiramycin. | Colistin |
Lincomycin | Clindamycin |
Spectinomycin |
Glycylcyclines antibiotics
Tigecycline is the new glycylcycline antibiotic, approved by the FDA in June 2005. It is broad-spectrum antibiotics. it is effective against gram-positive, gram-negative, and multidrug-resistant pathogens. it is effective for the treatment of complicated skin infection and intra-abdominal infection.
- Tigecycline
Macrocyclic antibiotics:
- Fidaxomicin.
Glycopeptides:
MOA → Bacterial cell wall synthesis drug. bacteriocidal.
glycopeptides drugs
- Dalbavancin
- Oritavancin,
- Teicoplanin
- Telavancin,
- Vancomycin.
Monobactams:
- Aztreonam.
- Nitrofurantoin:
- Nitrofurantoin.
Oxacephalosporins:
- Flomoxef,
- Latamoxef.
Sulphonamides Antimicrobial drug
Structure → analogs of p-aminobenzoic acid (PABA.
MOA → bacteriostatic.
it is a synthetic antimicrobial agent.
Uses of Sulphonamides antimicrobial drug: sulfonamide mainly used these days with a combination.
- Urinary tract infection,
- Respiratory tract infection,
- Sexually tract infection,
- skin infection.
Classification | Sulphonamides drugs |
Short-acting Sulfonamide drugs | Sulfisoxazole, Sulfamethizole |
Intermediate-acting sulfonamide drug | Sulfamethoxazole, Sulfamoxole |
Longe acting Sulfonamide drugs | Sulfadoxine, Sulphamethixypyridazine |
Topical drugs | Silver Sulfadiazine, Mafenide, Sulfacetamide |
Synergistic combination:
- Trimethoprim + sulfamethoxazole (Cotrimoxazole),
- Sulfadoxine + Pyrimethamine.
Cyclic Lipopeptides:
- Daptomycin.
Diaminopyrimidines:
- Trimethoprim.
Quinolones:
They are effective against Gram-negative aerobes, gram-positive cocci. this group of antibacterial drugs has broader antimicrobial activity.
uses of quinolones:
- urinary tract infection,
- bacterial diarrhea,
- Salmonella typhi infection,
- sexually transmitted infection,
- soft tissue, and wound infection,
- respiratory tract infection,
Classification | Quinolones drugs |
1st generation drugs. | Ciprofloxacin, Ofloxacin, Pefloxacin, Lomefloxacin, Nalidixic acid |
2nd Generation | Levofloxacin, Prulifloxacin |
3rd generation. | Sparfloxacin, Gatifloxacin |
4th generation | Moxifloxacin, Trovafloxacin, Finafloxacin. |
Tetracycline antibiotics
Tetracycline is a broad-spectrum bacteriostatic antibiotic drug. it has a 4 cyclic anthracycline ring structure. it is used for the treatment of,
- fever,
- Typhus fever,
- Pneumonia,
- respiratory tract infection,
- genitourinary infection,
- dental infection,
- ENT infection,
- Gynecological infection.
Doxycyclin |
Tetracycline |
Minocycline |
Tigecycline |
Source:
- Principles of pharmacology: h. L Sharma and K. K Sharma. paras medical publisher.
- Drug today India,
- CIMS India,
- Pharma ecology Diploma in pharmacy,
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