Storch G A, Krogstad D J
J Clin Invest. 1981 Sep;68(3):639-45. doi: 10.1172/jci110298.
Enterococci are resistant to penicillin killing in vivo and in vitro. Because some bacteria resistant to penicillin killing have reduced autolytic activity, we examined the lysis of clinical enterococcal isolates suspended in buffer (spontaneous lysis), and compared it with their susceptibility to antibiotic-induced lysis and killing. We found significant correlations between spontaneous and antibiotic-induced lysis, using five antibiotics that inhibit cell wall synthesis (penicillin, cephalothin, bacitracin, cycloserine, and vancomycin). Among isolates, strains more rapidly lysed by one antibiotic were more rapidly lysed by the other antibiotics, and more susceptible to spontaneous lysis. In studies involving a single strain grown in different media, spontaneous lysis also correlated closely with antibiotic-induced lysis. These results are consistent with a common mechanism for spontaneous and antibiotic-induced lysis, such as the autolytic enzyme system. Human serum was one of the least permissive media tested for enterococcal growth and antibiotic-induced lysis and killing. We suggest that the inhibitory effect of human serum on growth and the activation of the enterococcal autolytic enzyme system may be a critical factor in the resistance of enterococcal endocarditis to treatment with penicillin alone.
肠球菌在体内和体外均对青霉素杀伤具有抗性。由于一些对青霉素杀伤具有抗性的细菌自溶活性降低，我们检测了悬浮于缓冲液中的临床肠球菌分离株的裂解情况（自发裂解），并将其与它们对抗生素诱导的裂解和杀伤的敏感性进行了比较。我们使用五种抑制细胞壁合成的抗生素（青霉素、头孢噻吩、杆菌肽、环丝氨酸和万古霉素）发现自发裂解和抗生素诱导的裂解之间存在显著相关性。在分离株中，被一种抗生素更快裂解的菌株也被其他抗生素更快裂解，并且对自发裂解更敏感。在涉及在不同培养基中生长的单一菌株的研究中，自发裂解也与抗生素诱导的裂解密切相关。这些结果与自发裂解和抗生素诱导的裂解的共同机制一致，例如自溶酶系统。人血清是测试的对肠球菌生长以及抗生素诱导的裂解和杀伤最不利的培养基之一。我们认为人血清对生长的抑制作用以及肠球菌自溶酶系统的激活可能是肠球菌性心内膜炎单独用青霉素治疗耐药的关键因素。
