PubMed · 9376934
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F Manresa. 1997. [Resistant pneumococcus].. https://doi.org/10.1016/s0300-2896(15)30560-3
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Six cephalosporins of pharmacological interest, cephalexin, cephuroxime, cephazolin, cephoperazone sodium salt, cephatrizin free acid and cephonicid disodium salt, were analysed by electrospray mass spectrometry. [M - Na]- anions were produced in high yield in the case of cephalexin, cephuroxime, cephazolin and cephoperazone, leading to signals at least two orders of magnitude more intense than those related to [M + Na]+ cations observed in the positive ion mode. In cephatrizin, [M - H]- represented the most abundant species, whereas in cephonicid the [M - 2Na + H]- anions were easily produced. No fragment ions were detectable in the electrospray spectra of any of the compounds, and MSn turned out to be essential to draw the fragmentation patterns. Most of these patterns were related to the substituent of the 7-aminocephalosporin nucleus, suggesting that the nucleus itself is highly stable.
The Streptococcus milleri group are uniformly susceptible to penicillin G, but their susceptibilities to different cephalosporins vary considerably. The antimicrobial susceptibilities of 100 clinically significant strains of the S. milleri group to 16 cephalosporins were determined by the agar dilution method. The majority of first-generation cephalosporins were highly active. Cefamandole, cefuroxime and cefprozil were the most active second-generation agents examined. Third-generation parenteral cephalosporins exhibited excellent activity, with the exception of ceftazidime. The most active of the oral preparations of this group was cefpodoxime, with cefixime and ceftibuten being considerably less active. MICs of cefepime, the only fourth-generation cephalosporin tested, were higher than those of cefotaxime and ceftriaxone.