Gebre-Yohannes A, Drasar B S
National Research Institute of Health, Addis Ababa, Ethiopia.
J Med Microbiol. 1988 Dec;27(4):285-9. doi: 10.1099/00222615-27-4-285.
A total of 199 Shigella dysenteriae isolates resistant to one or more antibiotics and belonging to types 1, 2, 3, 4, 6 and 7 was examined by one-step broth mating with Escherichia coli K12 and, if non-conjugative, additionally by triparental crosses with the conjugative plasmids X and delta. Of the S. dysenteriae type 1 (Shiga's bacillus) strains, 96% harboured conjugative plasmids. During 1974-79, isolates of Shiga's bacillus carried conjugative plasmids coding for ACSSuT (ampicillin, chloramphenicol, streptomycin, sulphonamide, tetracycline) resistance that transferred at low frequencies (less than 10(-4). After 1980, however, about 50% of isolates of Shiga's bacillus with this resistance (R)-type carried conjugative plasmids that transferred at high frequencies (10 degrees-10(-2)) and that expressed the ACT determinant only. The introduction of a new clone of Shiga's bacillus into Ethiopia in 1980 is suspected. Conjugative plasmids coding for SSuT resistance were detected in S. dysenteriae types 2, 3, and 4. Non-conjugative SSu determinants in S. dysenteriae type 3 were mobilised by conjugative plasmids X and delta. R-type CSSuT in strains of types 2 and 7, and R-type ACST in type-3 strains were neither transferable nor mobilisable and are probably determined chromosomally.
对总共199株对一种或多种抗生素耐药且属于1、2、3、4、6和7型的痢疾志贺氏菌分离株，通过与大肠杆菌K12进行一步肉汤交配进行检测，如果是非接合型的，则另外通过与接合质粒X和δ进行三亲本杂交来检测。在1型痢疾志贺氏菌（志贺氏杆菌）菌株中，96%含有接合质粒。在1974 - 1979年期间，志贺氏杆菌的分离株携带编码ACSSuT（氨苄青霉素、氯霉素、链霉素、磺胺、四环素）耐药性的接合质粒，其转移频率较低（小于10^(-4)）。然而，1980年以后，约50%具有这种耐药（R）型的志贺氏杆菌分离株携带转移频率较高（10^0 - 10^(-2)）且仅表达ACT决定簇的接合质粒。怀疑1980年有一个新的志贺氏杆菌克隆引入埃塞俄比亚。在2、3和4型痢疾志贺氏菌中检测到编码SSuT耐药性的接合质粒。3型痢疾志贺氏菌中的非接合型SSu决定簇可被接合质粒X和δ动员。2型和7型菌株中的R型CSSuT以及3型菌株中的R型ACST既不可转移也不可动员，可能由染色体决定。
