Epidemiological and genetical analyses of clinical isolates resistant to newly developed antimicrobials

我们检测了385株临床分离的铜绿假单胞菌，并选择了90株对所测试的23种抗菌药物中的至少一种具有耐药性。对这些菌株进行了血清型、噬菌体和质粒型的检测，并分析了它们与耐药性的关系。在庆大霉素的情况下，耐药株和敏感株之间的差异最大。耐药株多为血清型I型或非分型株。1984年分离的不同来源的GM耐药株均表现出相同的多重耐药，分成I型血清型和非分型噬菌体，并含有编码多重耐药的非接合微质粒。自1985年以来，已零星分离到相同类型的菌株。1985年以来发现的接合传播型耐药株表现出不同的多重耐药性，且大多数为血清非分型株。耐诺沙星铜绿假单胞菌的增加伴随着新的喹诺酮类抗菌药物的使用增加。对药物敏感的临床分离株可突变为更高水平的喹诺酮类耐药株，同时或不伴有对其他药物敏感性的变化。表达对两种或两种以上抗菌药敏感性变化的突变体，其外膜蛋白发生了不同程度的变化，导致药物通透性的变化。

We examined 385 clinical isolates of P.aeruginosa and selected 90 strains resistant to at least one of 23 antibacterials tested. Using these strains, we determined their serum type, phage type and plasmid type and analysed their relationship with their drug-resistances. There found greatest differences between drug-resistant and sensitive strains in the case of gentamicin. GM-resistant strains belonged mostly to serum type I or nontypable. All of the GM-resistant isolates from different origin isolated in 1984 expressed the same multiple resistance, were grouped to serum type I and phage nontypable, and possessed nonconjugative miniplasmid encoding the multiple resistance. The same type strains have been isolated sporadically since 1985. Conjugally transmissible GM-resistant isolates showing different multiple resistance were found since 1985 and most of them were serum-nontypable. Thus we suspect the nosocomial infection in our hospital.Developement of drug-resistance owing to the abundant use of antimicrobials was demonstrated in the increase of norfloxacin-resistant P.aeruginosa accompanied with the increased use of new quinolone antimicrobials. The drug-sensitive clinical isolates were able to mutate to higher level of quinolone resistance with or without accompanying the change of sensitivities to other drugs. Mutants expressing the change of sensitivity to 2 or more kind of antimicrobials showed various changes in their outer-membrane proteins, resulting in the change of drug-permeability.