Okamoto S, Suzuki Y, Mise K, Nakaya R
J Bacteriol. 1967 Nov;94(5):1616-22. doi: 10.1128/jb.94.5.1616-1622.1967.
The occurrence of a chloramphenicol-acetylating enzyme, similar to that found in Escherichia coli, carrying an R factor was investigated in various gram-negative bacilli. The acetylated products of chloramphenicol were identified by chromatography and quantitatively assayed after benzene extraction. The investigated strains were of the Salmonella-Arizona group, the Klebsiella-Aerobacter group, Serratia marcescens, the Proteus group, and Pseudomonas aeruginosa, most of which were isolated from 1947 to 1957. Both chloramphenicol-sensitive and -resistant strains were included, but none of them was able to transfer chloramphenicol resistance by conjugation. In the Proteus group, a significant level of a chloramphenicol-acetylating enzyme was found in most strains, whether they were sensitive or resistant to chloramphenicol; the resistant strains showed higher levels of the enzyme. Some chloramphenicol-sensitive strains lacked this enzyme. Only the sensitive strains containing the enzyme could easily produce chloramphenicol-resistant mutants with higher enzyme activity. Thus, the chloramphenicol resistance of this group can be reasonably explained on the basis of the chloramphenicol-acetylating enzyme. All of the Pseudomonas aeruginosa strains were resistant to chloramphenicol, and most strains showed low levels of the enzyme (which, however, did not appear sufficient to explain their resistance). All of the strains of the other groups (except one strain of Enterobacter cloacae) lacked the enzyme, although most strains of the Klebsiella-Aerobacter group and of S. marcescens were resistant to chloramphenicol. With respect to the origin of the resistance gene of the R factor, it is noteworthy that the strains of Proteus mirabilis isolated in 1947 possessed this enzyme before the discovery of chloramphenicol.
在各种革兰氏阴性杆菌中，对一种类似于在携带R因子的大肠杆菌中发现的氯霉素乙酰化酶的出现情况进行了研究。氯霉素的乙酰化产物通过色谱法进行鉴定，并在苯萃取后进行定量分析。所研究的菌株属于沙门氏菌-亚利桑那菌群、克雷伯菌-气杆菌菌群、粘质沙雷氏菌、变形杆菌属和铜绿假单胞菌，其中大多数是在1947年至1957年期间分离得到的。包括对氯霉素敏感和耐药的菌株，但它们均不能通过接合转移氯霉素耐药性。在变形杆菌属中，大多数菌株无论对氯霉素敏感与否，都发现有显著水平的氯霉素乙酰化酶；耐药菌株的该酶水平更高。一些对氯霉素敏感的菌株缺乏这种酶。只有含有该酶的敏感菌株能够容易地产生具有更高酶活性的氯霉素耐药突变体。因此，该菌群的氯霉素耐药性可以基于氯霉素乙酰化酶得到合理的解释。所有铜绿假单胞菌菌株均对氯霉素耐药，且大多数菌株的该酶水平较低（然而，这似乎不足以解释它们的耐药性）。其他所有菌群的菌株（除了一株阴沟肠杆菌）均缺乏该酶，尽管克雷伯菌-气杆菌菌群和粘质沙雷氏菌的大多数菌株对氯霉素耐药。关于R因子耐药基因的起源，值得注意的是，1947年分离的奇异变形杆菌菌株在氯霉素被发现之前就已拥有这种酶。
