부산대학교 도서관

A colistin-resistant Enterobacter aerogenes[study code 12264] was isolated from the tracheal aspirate of a 71-year-old male patient in the General Hospital [GH] in Pula, Croatia. The patient was previously treated in University Hospital Centre in Rijeka with colistin in order to eradicate Acinetobacter baumanniiisolate, susceptible only to colistin and tigecycline. Genes encoding ESBLs [blaTEM, blaSHV, blaCTX-M, blaPER-1] were screened by PCR. The strain was shown to possess blaCTX-M-15and blaTEM-1genes. To asses genes possibly involved in resistance to colistin the chromosomal enconding mgrBgene and the plasmid-mediated mcr-1and mcr-2genes were screened as described previously. Mcr-1and mcr-2genes were not detected and mgrBgene presented a wild-type sequence. PCR-based Replicon typing method [PBRT] conducted on an E. aerogenesisolate, showed that the strain carried an IncN plasmid. Adaptive mechanisms such as changes of the bacterial cell outer membrane that cause porin decrease or presence of an efflux pump, due to selection pressure exerted by the therapeutic administration of colistin, could be responsible for the development of colistin resistance in our strain, as recently reported in E. aerogenesfrom France. Due to effective infection control measures, the colistin-resistant strain did not spread to other patients or hospital wards. This is the first report of an ESBL-producing, colistin-resistant E. aerogenesin clinically relevant samples such as endotracheal aspirate and blood culture, showing the presence of this rare resistance profile among Gram-negative bacteria.