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What are the cephalosporins? How is it different from penicillin? How to choose it?

Time:2022-09-27 14:28:22 source:psychiatricethics.com author:Leisure vacation Read:953次
What are the cephalosporins? How is it different from penicillin? How to choose it?

#Healthy大年# Since its inception, penicillin has become a magic drug against streptococcus and diphtheria bacillus, saving many lives in World War II. Over time, more and more bacteria became resistant to penicillin, and because of its narrow antibacterial spectrum and its allergy that can cause shock, penicillin gradually faded away. Penicillin works because it acts on the penicillin binding site on the bacterial cell wall, disrupting the synthesis of the bacterial cell wall and killing the bacteria during the reproductive period. The chemical structure that works is called the functional group, and the functional group of penicillin is the structure of β-lactam. After several generations of mutation, bacteria produce beta-lactamase by themselves to resist the effect of penicillin, making penicillin useless. Scientists have gradually developed enzyme-resistant penicillin methicillin, oxacillin, and dicloxacillin based on the structure of β-lactam; broad-spectrum acid and enzyme-intolerant amoxicillin and ampicillin; anti-Pseudomonas aeruginosa Merlot cillin, piperacillin, etc. Scientists later developed broad-spectrum, high-efficiency enzyme-resistant carbapenems, including panipenem, imipenem, ertapenem, biapenem, and meropenem. These antibiotics kill Gram-positive It has strong antibacterial effect on aerobic and anaerobic bacteria. Due to its strong antibacterial effect, it is commonly used in clinical practice for multidrug-resistant bacterial infection, severe pneumonia infection, etc. However, penicillin drugs also have many shortcomings, such as high renal toxicity, poor stability of dry powder, and extremely unstable when dissolved in water. Compatibility with other drugs will destroy the structure and fail! At the same time as the modification of natural penicillin, the world was looking for other antibiotics from microorganisms, and cephalosporins were extracted from microorganisms. Cephalosporins also have the structure of β-lactam. The difference is that the five-membered thiazole ring in the parent nucleus of penicillin has become the six-membered dihydrothiazole ring of cephalosporins. The development of cephalosporins is extremely fast. Can be divided into five generations. The first generation of cefazolin, cephalexin, cefradine, etc.; the second generation of cefuroxime, cefamandole, cefotiam, cefaclor, cefprozil, etc.; the third generation of ceftazidime, ceftriaxone, cefoperazone, ceftriaxone Cefepime, etc.; fourth-generation cefepime, cefpirome, etc.; fifth-generation cefepime. Their respective antibacterial spectrum is as follows: So how do we distinguish between Gram-positive and Gram-negative bacteria? After the bacteria are stained with gentian violet and enhanced with iodine, gram-positive bacteria will not be decolorized by alcohol, so they will appear purple; while gram-negative bacteria can be decolorized by alcohol, so they will appear red . The cell wall of Gram-positive bacteria is thicker, single-layered, and contains teichoic acid esters, while the cell wall of Gram-negative bacteria is multi-layered, but its thickness is lower, with an outer membrane, containing lipopolysaccharide. In treatment, most gram-positive bacteria are sensitive to penicillin, while gram-negative bacteria are not sensitive to penicillin, and the latter are more sensitive to streptomycin and chloramphenicol. Most pyogenes are gram-positive bacteria, which can produce exotoxins that make people sick and have strong virulence; while most enteric bacteria belong to gram-negative bacteria, which can produce endotoxins and are virulent weaker. Understanding gram-positive and negative bacteria will help in clinical empirical drug selection. Cephalosporins have a lower incidence of allergic reactions than penicillins, and no skin test is required before use. Treponema pallidum and Bacillus anthracis are still the first choice. In addition, when taking cephalosporins, most varieties will inhibit the activity of acetaldehyde dehydrogenase in the liver. If you drink alcohol at this time, acetaldehyde cannot be converted into acetic acid, which will accumulate in the body, causing discomfort such as dizziness, dizziness, and nausea. Difficulty breathing, increased heart rate, decreased blood pressure, shock, etc. We call it the disulfiram reaction.

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