RESUMO
Ninety-two strains of Serratia marcescens isolated from 5 hospitals were analyzed for plasmid profile, antimicrobial drug resistance pattern, biotyping, and production of pigment. Ninety-three percents of strains were resistant to chloramphenicol (Cm), tetracycline (Tc), sulfisoxazole (Su), cefazolin (Cz), ampicillin (Ap), and rifampin (Rf). A majority of strains were susceptible to amikacin (Ak), ciprofloxacin (Ci), and cefotaxim (Ct). Fifty-four resistance patterns were found in 94 strains and the most prevalent resistance pattern was CmTcSuApCzRf. Seventeen (17.4%) isolates could transfer their partial resistance to E. coli or Klebsiella pneumoniae by conjugation. Twenty-seven plasmid profiles in 54 strains (58.7%) were detected, however no predominant patterns were seen in isolates from each hospital. Eleven biotypes were detected. The common types were A3b (29.4%) and A8b (27.1%), predominant types were found in each hospital. Twenty strains from 4 of 5 hospitals showed consistence of 3 types. These results indicate that plasmid profile analysis, Grimont biotyping, and resistance pattern type of strains in combination are useful as an epidemiological tool for S. marcescens isolates and some of isolates were confirmed as nosocomial strains.