Classification
The cephalosporin nucleus can be modified to gain different properties. Cephalosporins are sometimes grouped into "generations" by their antimicrobial properties. The first cephalosporins were designated first-generation cephalosporins, whereas, later, more extended-spectrum cephalosporins were classified as second-generation cephalosporins. Each newer generation of cephalosporins has significantly greater Gram-negative antimicrobial properties than the preceding generation, in most cases with decreased activity against Gram-positive organisms. Fourth-generation cephalosporins, however, have true broad-spectrum activity.
The classification of cephalosporins into "generations" is commonly practised, although the exact categorization of cephalosporins is often imprecise. For example, the fourth generation of cephalosporins is not recognized as such, in Japan. In Japan, cefaclor is classed as a first-generation cephalosporin, even though in the United States it is a second-generation one; and cefbuperazone, cefminox, and cefotetan are classed as second-generation cephalosporins. Cefmetazole and cefoxitin are classed as third-generation cephems. Flomoxef, latamoxef are in a new class called oxacephems.
Most first-generation cephalosporins were originally spelled "ceph-" in English-speaking countries. This continues to be the preferred spelling in the United States, Australia and New Zealand, while European countries (including the United Kingdom) have adopted the International Nonproprietary Names, which are always spelled "cef-". Newer first-generation cephalosporins and all cephalosporins of later generations are spelled "cef-", even in the United States.
Some state that, although cephalosporins can be divided into five or even six generations, the usefulness of this organization system is of limited clinical relevance.
Fourth-generation Cephalosporins as of March, 2007 were considered to be "a class of highly potent antibiotics that are among medicine's last defenses against several serious human infections" according to the Washington Post.
The mnemonic "LAME" is used to note organisms that cephalosporins do not have activity against: Listeria, Atypicals (including mycoplasma and chlamydia), MRSA, and enterococci.
Exception: 5th generation Cephalosporins are effective against MRSA
| # | Members | Description |
|---|---|---|
| 1 | Cefacetrile (cephacetrile), Cefadroxil (cefadroxyl; Duricef), Cephalexin (cephalexin; Keflex), Cefaloglycin (cephaloglycin), Cefalonium (cephalonium), Cefaloridine (cephaloradine), Cefalotin (cephalothin; Keflin), Cefapirin (cephapirin; Cefadryl), Cefatrizine, Cefazaflur, Cefazedone, Cefazolin (cephazolin; Ancef, Kefzol), Cefradine (cephradine; Velosef), Cefroxadine, Ceftezole. | Gram-positive: Activity against penicillinase-producing, methicillin-susceptible staphylococci and streptococci (though they are not the drugs of choice for such infections). No activity against methicillin-resistant staphylococci or enterococci. Gram-negative: Activity against Proteus mirabilis, some Escherichia coli, and Klebsiella pneumoniae ("PEcK"), but have no activity against Bacteroides fragilis, Pseudomonas, Acinetobacter, Enterobacter, indole-positive Proteus, or Serratia. |
| 2 | Cefaclor (Ceclor, Distaclor, Keflor, Raniclor), Cefonicid (Monocid), Cefprozil (cefproxil; Cefzil), Cefuroxime (Zefu, Zinnat, Zinacef, Ceftin, Biofuroksym, Xorimax), Cefuzonam. Second generation cephalosporins with antianaerobe activity: Cefmetazole, Cefotetan, Cefoxitin. The following cephems are also sometimes grouped with second-generation cephalosporins: Carbacephems: loracarbef (Lorabid); Cephamycins: cefbuperazone, cefmetazole (Zefazone), cefminox, cefotetan (Cefotan), cefoxitin (Mefoxin), Cefotiam. | Gram-positive: Less than first-generation. Gram-negative: Greater than first-generation: HEN (Haemophilus influenzae, Enterobacter aerogenes and some Neisseria + the PEcK described above. |
| 3 | Cefcapene, Cefdaloxime, Cefdinir (Zinir, Omnicef, Kefnir), Cefditoren, Cefetamet, Cefixime (Zifi, Suprax), Cefmenoxime, Cefodizime, Cefotaxime (Claforan), Cefovecin (Convenia), Cefpimizole, Cefpodoxime (Vantin, PECEF), Cefteram, Ceftibuten (Cedax), Ceftiofur, Ceftiolene, Ceftizoxime (Cefizox), Ceftriaxone (Rocephin). Third-generation cephalosporins with antipseudomonal activity: Cefoperazone (Cefobid), Ceftazidime (Fortum, Fortaz). The following cephems are also sometimes grouped with third-generation cephalosporins: Oxacephems: latamoxef (moxalactam). | Gram-positive: Some members of this group (in particular, those available in an oral formulation, and those with anti-pseudomonal activity) have decreased activity against Gram-positive organisms. Gram-negative: Third-generation cephalosporins have a broad spectrum of activity and further increased activity against Gram-negative organisms. They may be particularly useful in treating hospital-acquired infections, although increasing levels of extended-spectrum beta-lactamases are reducing the clinical utility of this class of antibiotics. They are also able to penetrate the CNS, making them useful against meningitis caused by pneumococci, meningococci, H. influenzae, and susceptible E. coli, Klebsiella, and penicillin-resistant N. gonorrhoeae. Since 2007, third-generation cephalosporins (ceftriaxone or cefixime) have been the only recommended treatment for gonorrhea in the United States. |
| 4 | Cefclidine, Cefepime (Maxipime), Cefluprenam, Cefoselis, Cefozopran, Cefpirome (Cefrom), Cefquinome. The following cephems are also sometimes grouped with fourth-generation cephalosporins: Oxacephems: flomoxef | Gram-positive: They are extended-spectrum agents with similar activity against Gram-positive organisms as first-generation cephalosporins. Gram-negative: Fourth-generation cephalosporins are zwitterions that can penetrate the outer membrane of Gram-negative bacteria. They also have a greater resistance to beta-lactamases than the third-generation cephalosporins. Many can cross the blood–brain barrier and are effective in meningitis. They are also used against Pseudomonas aeruginosa. |
| 5 | Ceftobiprole, Ceftaroline | Ceftobiprole has been described as "fifth-generation" cephalosporin, though acceptance for this terminology is not universal. Ceftobiprole (and the soluble prodrug medocaril) are on the FDA fast-track. Ceftobiprole has powerful antipseudomonal characteristics and appears to be less susceptible to development of resistance. Ceftaroline has also been described as "fifth-generation" cephalosporin, but does not have the anti-pseudomonal or VRE coverage of ceftobiprole |
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