Kurihara T, Sugita M, Motai S, Kurashige S
Department of Laboratory Medicine, Tatebayashi Kosei Hospital College of Medical Care and Technology, Gunma University.
Kansenshogaku Zasshi. 1993 Mar;67(3):202-6. doi: 10.11150/kansenshogakuzasshi1970.67.202.
A study was made on the MIC distributions of chlorhexidine and benzalkonium chloride against clinically isolated 178 strains of Pseudomonas aeruginosa to find out the existence of strains resistant to those disinfectants and also on the in vitro induction of resistance to both drugs. The MIC of chlorhexidine gluconate was found to be distributed from 78 to 625 micrograms/ml with a single peak at 312 micrograms/ml. All 178 strains of clinical isolates were sensitive to chlorhexidine and none could be induced to become chlorhexidine resistant in vitro, suggesting that P. aeruginosa can not easily acquire chlorhexidine resistance. On the other hand, the MIC of benzalkonium chloride was distributed in two peaks; one peak was benzalkonium sensitive at 625 micrograms/ml (150 strains/178 strains: 84.3%) and the another peak was benzalkonium resistant at 5,000 micrograms/ml (28 strains/178 strains; 15.7%). Six (4.0%) of the 150 benzalkonium sensitive strains acquired benzalkonium resistance by in vitro induction of resistance; the MIC of 5 strains increased from 625 micrograms/ml to 2,500 micrograms/ml and that of the residual 1 strain increased from 312 micrograms/ml to 1,250 micrograms/ml. However, no change of MIC was observed in 28 benzalkonium-resistant strains of clinically isolated P. aeruginosa by in vitro resistance induction. Strains with MIC more than 5,000 micrograms/ml could not be obtained at all. The results suggest that the benzalkonium resistance can be introduced in P. aeruginosa whereas the resistance-acquiring rate is low. These results suggest that chlorhexidine gluconate is the first choice for prevention of Pseudomonas infection in the hospital and benzalkonium is also useful in 0.5% solution is used.
对氯己定和苯扎氯铵针对临床分离的178株铜绿假单胞菌的最低抑菌浓度（MIC）分布进行了研究，以查明对这些消毒剂耐药的菌株的存在情况，同时也研究了这两种药物的体外耐药诱导情况。发现葡萄糖酸氯己定的MIC分布在78至625微克/毫升之间，在312微克/毫升处有一个单峰。所有178株临床分离株对氯己定敏感，且在体外均不能被诱导产生氯己定耐药性，这表明铜绿假单胞菌不容易获得氯己定耐药性。另一方面，苯扎氯铵的MIC分布有两个峰；一个峰是对苯扎氯铵敏感的，MIC为625微克/毫升（150株/178株：84.3%），另一个峰是对苯扎氯铵耐药的，MIC为5000微克/毫升（28株/178株；15.7%）。150株对苯扎氯铵敏感的菌株中有6株（4.0%）通过体外耐药诱导获得了苯扎氯铵耐药性；5株的MIC从625微克/毫升增加到2500微克/毫升，其余1株的MIC从312微克/毫升增加到1250微克/毫升。然而，通过体外耐药诱导，在28株临床分离的对苯扎氯铵耐药的铜绿假单胞菌中未观察到MIC的变化。根本无法获得MIC超过5000微克/毫升的菌株。结果表明，铜绿假单胞菌可产生苯扎氯铵耐药性，但其耐药获得率较低。这些结果表明，葡萄糖酸氯己定是医院预防铜绿假单胞菌感染的首选药物，而0.5%溶液的苯扎氯铵也有用。
