Î’-Lactam antibiotic
The β -lactam antibiotics are a group of antibiotics / antibacterial anti-infectives, all of which have in its structure a four-membered formula lactam ring. They go back to the penicillin, bacteriologist Alexander Fleming, the Scottish 1928 extracted from cultures of the fungus Penicillium notatum, which at the same time is the most important and best-known representatives of this group. They all have a bactericidal effect by inhibiting peptidoglycan synthesis during cell division. Differences in efficacy were above all by differente affinity and ability to penetrate. β -lactam antibiotics are nowadays manufactured mainly semi-synthetic.
By 1940, Howard Walter Florey and Ernst developed Boris Chain drugs on the basis of penicillin, which were used a year later for the first time in therapy. But Fleming was awarded in 1945, together with the two other scientists, the Nobel Prize for Medicine. At that time, penicillin preparations were often used incorrectly, especially against pathogens that are naturally resistant to β -lactam antibiotics. Meanwhile, many originally sensitive pathogens have developed antibiotic resistance against β - Lactampräparate, so that there is always forced to develop new drugs.
Effectiveness
All β -lactam antibiotics are not effective against Mycoplasma, Chlamydia and Legionella. Also exist in some other bacteria acquired resistance based on a β -lactamase.
Side effects
β -lactam antibiotics are well-tolerated owing to the mechanism of action is usually to humans. They engage in the cell wall synthesis of dividing bacteria - this metabolic process does not occur in humans. However, now there are many allergies to penicillin and related substances, which can range from mild skin reactions up to anaphylactic shock in all grades. Also to be reckoned with cross reactions between the various β -lactam antibiotics.
Division into groups
Today, there are four groups of β -lactam antibiotics:
- Penicillins β -lactamase -sensitive ( labile ) penicillins Benzylpenicillin (penicillin G)
- Phenoxymethylpenicillin (penicillin V)
- Propicillin
- Azidocillin
- Flucloxacillin
- Dicloxacillin
- Cloxacillin
- Oxacillin
- Methicillin
- Aminopenicillins Amoxicillin
- Ampicillin
- Bacampicillin
- Mezlocillin
- Piperacillin
- Cephalosporins for parenteral use Cephalosporins without increasing β -lactamase stability Basiscephalosporine
- Cefuroxime
- Cefamandole
- Cefoxitin
- Cefotiam
- Cefotaxime
- Cefovecin
- Ceftazidime
- Cefepime
- Cefodizime
- Ceftriaxone
- Oralcephalosporine without increasing β -lactamase stability Cefaclor
- Cefadroxil
- Cefalexin
- Loracarbef
- Cefixime
- Cefuroxime axetil
- Cefetametpivoxil
- Ceftibuten
- Cefpodoxime proxetil
- Clavulanic acid in combination with amoxicillin
- Sulbactam
- Tazobactam in combination with piperacillin
- Carbapenems Imipenem in combination with cilastatin
- Meropenem
- Ertapenem
- Aztreonam
Resistance and mechanisms
During the use of β -lactam drugs Although rarely and slowly develop resistance against them, but they now represent a serious problem Here are three resistance mechanisms can be distinguished:
- Resistant penicillin - binding proteins
- Membrane changes
- Formation of β -lactamases
In order to obtain β -lactamase - stable penicillins are bulky groups introduced into the penicillin molecule which sterically hinder the β -lactamase. Also possible is the use of β -lactamase inhibitors such as clavulanic acid, sulbactam, or tazobactam.
β -lactam antibiotics not only block the division of bacteria including the cyanobacteria, but also the division of cyanelles, the photosynthetic organelles of Glaucocystaceaen and the chloroplasts of Physcomitrella mosses, liverworts ( Marchantia polymorpha ) and moss ferns ( Selaginella nipponica ). However, on the division of plastids of the highly developed vascular plants such as tomatoes in it have no effect. This is an indication that at higher plants show through evolutionary changes in the Plastidteilung β -lactam antibiotics on chloroplasts no longer effective.