Weinstein A J, Moellering R C
Antimicrob Agents Chemother. 1975 May;7(5):522-9. doi: 10.1128/AAC.7.5.522.
Combinations of cephalothin and aminoglycoside antibiotics are not currently used in the therapy of serious enterococcal infections, because clinical trials of these combinations have been unsuccessful. Studies of 28 enterococci isolated from patients with enterococcal bacteremia suggested three possible mechanisms for this in vivo antibiotic failure: (i) a relatively high level of resistance to cephalothin among all enterococci and especially those characterized as Streptococcus faecium, (ii) a significant incidence of high-level resistance to the aminoglycosides among certain strains of enterococci, and (iii) a failure of synergism to occur when cephalothin concentrations fall below the minimal inhibitory concentration of the enterococcus, as occurs during the in vivo metabolism and excretion of this antibiotic when given in standard doses for endocarditis.
目前,头孢噻吩与氨基糖苷类抗生素的联合用药并不用于严重肠球菌感染的治疗,因为这些联合用药的临床试验未取得成功。对从患有肠球菌菌血症患者中分离出的28株肠球菌进行的研究表明,体内抗生素治疗失败可能有三种机制:(i) 所有肠球菌,尤其是那些被鉴定为粪肠球菌的菌株,对头孢噻吩的耐药性相对较高;(ii) 某些肠球菌菌株对氨基糖苷类抗生素存在显著的高水平耐药现象;(iii) 当头孢噻吩浓度降至肠球菌的最低抑菌浓度以下时,协同作用无法发生,在以标准剂量给予心内膜炎患者使用该抗生素时,体内代谢和排泄过程中就会出现这种情况。