Miller A K, Celozzi E, Pelak B A, Stapley E O, Hendlin D
Antimicrob Agents Chemother. 1972 Oct;2(4):281-6. doi: 10.1128/AAC.2.4.281.
Cephamycins A, B, and C are naturally produced cephalosporin-type antibiotics. Although A and B were found to be more active than C against gram-positive organisms, they were not so active against such strains as are cephalosporin C or the semisynthetic antibiotics cephaloridine and cephalothin. Against gram-negative organisms, cephamycin C was more active than A or B and, in general, was as active as the cephalosporins. In addition, cephamycin C was active in vitro against clinically isolated strains resistant to the cephalosporins, such as Proteus, Providencia, and Escherichia coli. The in vitro antibacterial activity of cephamycin C, cephalothin, and cephaloridine is primarily bactericidal. A 10,000-fold increase in inoculum of a strain of Proteus mirabilis resulted in 200-fold or greater increases in minimal inhibitory and minimal bactericidal end points of cephalothin and cephaloridine, but only 10- and 16-fold increases, respectively, for cephamycin C. After 15 passages through antibiotic-containing broths, during which time a culture of E. coli showed an increase in minimal inhibitory concentrations of streptomycin of >1,000-fold, end points for cephamycin C increased 4-fold, for cephalothin, 1.5-to 6-fold, and for cephaloridine, 128-fold.
头孢霉素A、B和C是天然产生的头孢菌素类抗生素。虽然发现A和B对革兰氏阳性菌的活性比C更强，但它们对某些菌株的活性不如头孢菌素C或半合成抗生素头孢噻啶和头孢氨苄。对革兰氏阴性菌而言，头孢霉素C比A或B更具活性，总体上与头孢菌素的活性相当。此外，头孢霉素C在体外对临床分离出的对头孢菌素耐药的菌株具有活性，如变形杆菌、普罗威登斯菌和大肠杆菌。头孢霉素C、头孢氨苄和头孢噻啶的体外抗菌活性主要是杀菌性的。奇异变形杆菌菌株的接种量增加10000倍，导致头孢氨苄和头孢噻啶的最小抑菌和最小杀菌终点分别增加200倍或更多，但头孢霉素C仅分别增加10倍和16倍。在含抗生素的肉汤中传代15次后，在此期间大肠杆菌培养物对链霉素的最小抑菌浓度增加了1000倍以上，头孢霉素C的终点增加了4倍，头孢氨苄增加了1.5至6倍，头孢噻啶增加了128倍。
