a group of natural and semisynthetic antibiotics with similar chemical structures and biological properties. Natural cephalosporins—cephalosporin C and cephalosporin N (penicillin N)—were isolated in 1945 by the Italian microbiologist G. Brotzu from a mold of the genus Cephalosporium. The molecules of all the cephalosporins except cephalosporin N contain 7-aminocephalosporanic acid, which consists of β-lactam (A) and dihydrothiazine (B) rings:
The structure of 7-aminocephalosporanic acid is similar to that of the penicillin nucleus, 6-aminopenicillanic acid, which also contains a β-lactam ring. Since two side chains can be substituted in 7-aminocephalosporanic acid but only one in 6-aminopenicillanic acid, many more semisynthetic derivatives can be obtained from 7-aminocephalosporanic acid.
The cephalosporins are broad-spectrum antimicrobials, proving effective against staphylococci, streptococci, pneumococci, gonococci, meningococci, clostridia, the influenza bacillus (Haemophilus influenzae), Klebsiella, the colon bacillus, and a number of other microorganisms. The antimicrobial action of the cephalosporins is due, as in the case of the penicillins, to their ability to block the formation of the microbial cell wall. Unlike the penicillins, the cephalosporins rarely provoke an allergic reaction, and they are resistant to bacterial enzymes (β-lactamases), which destroy antibiotics.
Physicians generally prescribe semisynthetic cephalosporins, since they are more active than the natural ones. Among the semisynthetic ones are cephaloridine (Ceporin), cephalothin, cefazolin, cephalexin, cephradine, and cephaloglycin, all of which are used in the treatment of infectious diseases caused by microorganisms sensitive to these antibiotics. Since their spectrum of action is very broad, their use is especially indicated in infections of unknown etiology, in mixed infections, and in cases when the causative agent is highly resistant to penicillin or the patient is highly sensitive to penicillin.
REFERENCES
Klimov, A. N. Penitsilliny i tsefalosporiny. Leningrad, 1973.Milevskaia, Iu. L. “Tsefalosporiny (ikh svoistva i preimushchestva): Obzor literatury.” Meditsinskii referativnyi zhurnal, 1975, no. 4, pp. 82–86.
L. E. GOL’DBERG
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