Results of secondary antibiotics susceptibility test for gram negative bacilli resistant to primary susceptibility test in Yeungnam University Hospital / 영남의대학술지

ABSTRACT

Major pathogenic Gramnegative organisms such as P. aeruginosa, Serratia species, E. coli, Enterobacter species which are isolated from the specimens in large medical centers are greatly resistant to the commonly used antibiotics. Gramnegative bacilli, which had been isolated in Yeungnam Uni rersity Hospital during the period from December 1992 to April 1993 and turned out to be resistant to the primary antibiotics susceptibility test for chloramphenicoi, ampicillin, eephaiothin,- geniamicitt, tetracyclin, amikin and tobramycin, were subjected to the secondary antibiotics susceptibility test for aztreonam, ceftazidime, ciprofloxacine, cefotaxime, cefamandole, piperacillin, ticarcillin and sulfamethoxazole trimethopime. Out of 315 tested organisms, 167 organisms (53%) were resistant to all secondary antibiotics in vitro. Antimicrobial activity of ceftazidime (37.1%), aztreonam (11. %), ciprofloxacine (7.9%) against Gram negative bacilli were slightly more active than other antibiotics tested, while cefamandole was not active to all the Gramnegative bacilli tested. According to the specimens, E. coli was the most frequently resistant organisms to the primary antibiotics from urine, A. baumanii, from respiratory system and wounds, and P. aeruginosa from various specimens. In summary, Gram negative bacilli resistant to the primarily applied antibiotics also were resistant to the secondary antibiotics. Rearrangement of the antibiotics disks for the antibiotic susceptibility test should be considered.