Information AboutCephalosporin |
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HISTORY Cephalosporin was first isolated from cultures of '' Cephalosporium Acremonium '' from a sewer in Sardinia in 1948 by an Italian scientist Giuseppe Brotzu . He noticed that these cultures produced a substance that was effective against '' Salmonella Typhi '', the cause of Typhoid . The cephalosporins were developed as drugs at the Sir William Dunn School of Pathology at the University of Oxford and Keflin (cephalothin) was launched by Eli Lilly in 1964 . MODE OF ACTION Cephalosporins work the same way as synthesis of the Bacterial wall by inhibiting the final transpeptidation needed for the cross-links. This effect is bactericidal. THE GENERATIONS The cephalosporin nucleus can be modified to gain different properties. Cephalosporins are grouped into "generations" by their Antimicrobial properties. The first cephalosporins were designated first generation while 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; currently, four generations of cephalosporins are recognized. Conversely, the "older" generations of cephalosporins have greater gram positive ( Staphylococcus and Streptococcus ) coverage than the "newer" generations. There is some disagreement on the definition of generations. The fourth generation of cephalosporins is not yet recognized in Japan, and are included in the third generation instead. In Japan, Cefaclor is classed as a first generation cephalosporin; and cefbuperazone, cefminox and cefotetan are classed as second generation cephalosporins. Cefbuperazone, cefminox, and cefotetan are classed as second generation cephems. Cefmetazole and cefoxitin are classed as third generation cephems. Flomoxef, latamoxef are in a new class called oxacephems. First generation cephalosporins First generation cephalosporins generally contain 'ph' in their names (except cefadroxil, cefaloridine, cefazolin and newer varieties) in the United States. In other nations, 'f' is commonly used. They have a Spectrum Of Activity that includes penicillinase-producing, methicillin-susceptible Staphylococci and Streptococci , though they are not the drugs of choice for such infections. They also have activity against some '' Escherichia Coli '', '' Klebsiella Pneumoniae '' and '' Proteus Mirabilis '', but have no activity against '' Bacteroides Fragilis '', Enterococci , methicilllin-resistant staphylococci, '' Pseudomonas '', '' Acinetobacter '', '' Enterobacter '', indole-positive '' Proteus '' or '' Serratia ''.
Second generation cephems The second generation cephalosporins have a greater Gram-negative spectrum while retaining some activity against Gram-positive cocci. They are also more resistant to Beta-lactamase .
Second generation carbacephem
Second generation antianaerobe cephalosporins
Second generation antianaerobe cephamycins
Third generation cephalosporins Third generation cephalosporins have a broad spectrum of activity against enteric gram-negative rods and thus are particularly useful in treating Hospital-acquired Infection s.
Cefoperazone combined with Sulbactam is sold as Sulperazon® . Third generation antipseudomonal Cephalosporins
Fourth generation cephalosporins Fourth generation cephalosporins have a greater spectrum of activity against gram-positive organisms than the third generation cephalosporins. They also have a greater resistance to beta-lactamases than the third generation cephalosporins. MOst importantly, they can cross Blood Brain Barrier and is effective against Meningitis .
Catecholic Cephalosporin
Fourth generation antipseudomonal Cephalosporins
Unknown generation cephems These cephems have progressed far enough to be named, but have not been assigned to a particular generation. Ceftobiprole (and the oral medocaril version) are on the FDA fast track. Ceftobiprole has powerful antipseudomonal characteristics and ''appears'' to be less susceptible to development of resistance.
Care should be taken not to confuse the names of cephalosporins, as many are quite similar. EXTERNAL LINKS
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