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microbiology ppt

  1. • A typical prokaryotic chromosome consists of a circular molecule of DNA localized in a region of the cytoplasm called the nucleoid. With few exceptions, no membrane surrounds a nucleoid, though the chromosome is packed insuch a way that a distinct boundary is visible between the nucleoid and the rest of the cytoplasm. Chromosomal DNA is folded into loops that are 50,000–100,000 bp long,held in place by molecules of protein and RNA. • Archaeal DNA is wrapped around globular proteins called Non-histones. The enzyme gyrase further folds and supercoils the entire prokaryotic chromosome like a skein of yarn into a compact mass. • In addition to chromosomes, many prokaryotic cells contain one or more plasmids, which are small molecules of DNA that replicate independently of the chromosome. Plasmids are usually circular and 1–5% of the size of a prokaryotic chromosome, ranging in size from a few thousand bp to a few million bp. Each plasmid carries information required for its own replication, and often for one or more cellular traits.Typically, genes carried on plasmids are not essential for normal metabolism, for growth, or for cellular reproduction but can confer advantages to the cells that carry them.
  2. • Fertility (F) plasmids carry instructions for conjugation, a process involved in transferring genes from one bacterial cell to another. • Resistance (R) plasmids carry genes for resistance to one or more antimicrobial drugs or heavy metals. By processes we will discuss shortly, certain cells can transfer resistance plasmids to other cells, which then acquire resistance to the same antimicrobial chemicals. One example of the effects of an R plasmid involves strains of Escherichia coli that have acquired resistance to the antimicrobials ampicillin, tetracycline, and kanamycin from a strain of the bacterium Pseudomonas. • Virulence plasmids carry instructions for structures, enzymes, or toxins that enable a bacterium to become pathogenic. For example, E. coli, a normal resident of the human gastrointestinal tract, causes diarrhea only when it carries plasmids that code for certain toxins.
  3. • Chemotherapeutic agents (synthetic antibiotics) are antimicrobial agents of synthetic origin useful in the treatment of microbial or viral disease. Examples: sulfonilamides, isoniazid, ethambutol, AZT, nalidixic acid and chloramphenicol. • Five modes of action of chemotherapeutic drugs. Various antimicrobial agents act by interfering with: • (1) cell wall synthesis • (2) plasma membrane integrity • (3) Nucleic acid synthesis • (4) Ribosomal function • (5) folate synthesis.
  4. • Antibiotics are chemicals that kill or inhibit the growth of bacteria and are used to treat bacterial infections. They are produced in nature by soil bacteria and fungi. • They may be of two types of antibiotic action .They are : 1)Bacteriostatic 2)Bacteriocidal • Bacteriostatic: Capable of inhibiting the growth or reproduction of bacteria. Examples: Tetracyclines, macrolides, clindamycin, trimethoprim/sulfamethoxazole, linezolid, and chloramphenicol . • Bactericidal: capable of killing bacteria including complete cell. Examples: Daptomycin, fluoroquinolones, metronidazole, nitrofurantoin, co- trimoxazole, telithromycin.
  5. List of Antibiotic Classes (Types of Antibiotics) • Penicillins • Tetracyclines • Cephalosporins • Quinolones • Lincomycins • Macrolides • Sulfonamides • Glycopeptides • Aminoglycosides • Carbapenems
  6. 1)Penicillins Another name for this class is the "beta-lactam" antibiotics, referring to their structural formula. The penicillin class contains five groups of antibiotics: aminopenicillins, antipseudomonal penicillins, beta- lactamase inhibitors, natural penicillins, and the penicillinase resistant penicillins. Common antibiotics in the penicillin class include: Generic Brand Name Examples Amoxicillin Amoxil Amoxicillin and clavulanate Augmentin, Augmentin ES-600 Ampicillin Unasyn Dicloxacillin N/A Oxacillin Bactocill Penicillin V potassium Penicillin VK Certain penicillinase-resistant penicillins (such as oxacillin or dicloxacillin) are inherently resistant to certain beta-lactamase enzymes by themselves. Others, for example, amoxicillin or ampicillin have greater antibacterial activity when they are combined with a beta-lactamase inhibitor like clavulanate, sulbactam, or tazobactam.
  7. 2. Tetracyclines • Tetracyclines are broad-spectrum against many bacteria and treat conditions such as acne, urinary tract infections (UTIs), intestinal tract infections, eye infections, sexually transmitted diseases, periodontitis (gum disease), and other bacterial infections. The tetracycline class contains drugs such as: Generic Brand Name Examples • Demeclocycline N/A • Doxycycline Doryx, Doxy 100, Monodox, Oracea, Vibramycin • Eravacycline Xerava • Minocycline Amzeeq, Dynacin, Minocin, Minolira, Solodyn, Ximino, Zilxi • Omadacycline Nuzyra • Sarecycline Seysara • Tetracycline Achromycin V
  8. Cephalosporins • There are five generations of cephalosporins, with increasing expanded coverage across the class to include gram-negative infections. Newer generations with updated structures are developed to allow wider coverage of certain bacteria. Cephalosporins are bactericidal (kill bacteria) and work in a similar way as the penicillins. • Cephalosporins treat many types of infections, including strep throat, ear infections, urinary tract infections, skin infections, lung infections, and meningitis. Common medications in this class include: Generic Brand Name Examples Generation • cefaclor N/A 2nd generation • cefadroxil Duricef 1st generation • cefdinir N/A 3rd generation • cephalexin Keflex 1st generation • cefprozil Cefzil 2nd generation • cefdinir N/A 3rd generation • cefepim Maxipime 4th generation
  9. • cefiderocol Fetroja 4th generation • cefotaxime N/A 3rd generation • cefotetan Cefotan 2nd generation • ceftaroline Teflaran 5th (next) generation • ceftazidime Avycaz, Fortaz, Tazicef 3rd generation • ceftriaxone N/A 3rd generation • cefuroxime Ceftin, Zinacef 2nd generation • The fifth generation (or next generation) cephalosporin known as ceftaroline (Teflaro) is active against methicillin-resistant Staphylococcus aureus (MRSA). Avycaz contains the the beta-lactamase inhibitor avibactam.
  10. Fluoroquinolones • The fluoroquinolones, also known as the quinolones, are a synthetic, bactericidal antibacterial class with a broad-spectrum of activity used in adults (not children). Due to risk of multiple serious side effects, the FDA has advised that they are not suitable for common infections such as sinusitis, bronchitis, and uncomplicated urinary tract infections. They should only be considered when treatment with other, less toxic antibiotics, has failed. Ask your doctor about the warnings associated with this class of drug before you take it. • The FDA has issued several strong warnings about this class due to potential disabling side effects. • Common drugs in the fluoroquinolone class include: Generic Brand Name Examples • ciprofloxacin Cipro, Cipro XR • delafloxacin Baxdela • levofloxacin N/A • moxifloxacin Avelox • gemifloxacin Factive • Several fluoroquinolones are also available in drop form to treat eye or ear infections.
  11. Lincomycins • This class has activity against gram-positive aerobes and anaerobes (bacteria that can live without oxygen), as well as some gram-negative anaerobes. • The lincomycin derivatives may be used to treat serious infections like pelvic inflammatory disease, intra-abdominal infections, lower respiratory tract infections, and bone and joint infections. Some forms are also used topically on the skin to treat acne. A single-dose vaginal cream is also available to treat certain bacterial vaginal infections (bacterial vaginosis). These drugs include: Generic Brand Name Examples • clindamycin Cleocin, Cleocin T, Clindets, Clindesse, Evoclin • lincomycin Lincocin
  12. Macrolides • The macrolides can be use to treat community-acquired pneumonia, pertussis (whooping cough), or for uncomplicated skin infections, among other susceptible infections. Ketolides are a newer generation of antibiotic developed to overcome macrolide bacterial resistance. • Frequently prescribed macrolides are: Generic Brand Name Examples • Azithromycin Zithromax • Clarithromycin Biaxin • Erythromycin E.E.S., Ery-Tab, Eryc • Fidaxomicin (ketolide) Dificid
  13. Sulfonamides • Sulfonamides are effective against some gram-positive and many gram-negative bacteria, but resistance is widespread. Uses for sulfonamides include urinary tract infections (UTIs), treatment or prevention of pneumocystis pneumonia, or ear infections (otitis media). • Familiar names include: Generic Brand Name Examples • sulfamethoxazole and trimethoprim Bactrim, Bactrim DS, Septra • sulfasalazine Azulfidine
  14. Glycopeptide Antibiotics • Members of this group may be used for treating methicillin-resistant staphylococcus aureus (MRSA) infections, complicated skin infections, C. difficile-associated diarrhea, and enterococcal infections such as endocarditis which are resistant to beta-lactams and other antibiotics. • Common drug names include: Generic Brand Name Examples • Dalbavancin Dalvance • Oritavancin Orbactiv, Kimyrsa • Telavancin Vibativ • Vancomycin Firvanq, Vancocin
  15. Aminoglycosides • Aminoglycosides inhibit bacterial synthesis by binding to the 30S ribosome and act rapidly as bactericidal antibiotics (killing the bacteria). These drugs are usually given intravenously (in a vein through a needle); inhaled and ophthalmic (eye) dose forms are also available. Examples in this class are: Generic Brand Name Examples • Gentamicin Genoptic, Gentak • Tobramycin Aktob, Kitabis Pak, TOBI, Tobrex • Amikacin Amikin, Arikayce
  16. Carbapenems • These injectable beta-lactam antibiotics have a wide spectrum of bacteria-killing power and may be used for moderate to life-threatening bacterial infections like stomach infections, pneumonias, kidney infections, multidrug-resistant hospital-acquired infections and many other types of serious bacterial illnesses. They are often saved for more serious infections or used as "last-line" agents to help prevent resistance. • Members of this class include: Generic Brand Name Examples • Imipenem and cilastatin Primaxin, Recarbrio • Meropenem Merrem Vabomere • Ertapenem Invanz • Note: Recarbrio is a combination medicine that contains imipenem, cilastatin and the beta-lactamse inhibitor relebactam. Vabomere is a combination product that contains meropenem and the beta-lactamse inhibitor vaborbactam.
  17. • Amoxicillin • Doxycycline • Cephalexin • Ciprofloxacin • Clindamycin • Metronidazole • Azithromycin • Sulfamethoxazole and trimethoprim • Amoxicillin and clavulanate • Levofloxacin *(All these antibiotics are already mentioned in above slides)
  18. Thankyou for your attention
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