In order to investigate phenotype and genotype of Salmonella enterica subsp. enterica serovar Enteritidis, Forty-eight S. Enteritidis isolates from diarrhea patients were analysed using antimicrobial resistance typing, Phage typing, and Pulsed field gel electrophoresis in Seoul from 2004 to 2005. All of S. Enteritidis were resistant to streptomycin(SM, 37.5%), ampicillin(AM, 43.8%), t icarcillin(TIC, 43.8%), chloramphenicol(CM, 29.2%), t etracycline(TE, 10 .4%) and nalidixic acid(NA, 18.8%) among 16 antimicrobial drugs. Of 48 S. Enteritidis, 8 isolates(16.7%) were resistant to 1 drug, 3 isolates( 6.3%) to 2 drugs, 1 isolate (2.1%) to 3 drugs and 17 isolates(35.7%) to 4 drugs. The basic pattern of 4 drugs resistance was SM, TIC, TE, and CM but 1 drug resistant isolates represent all nalidixic acid resistance. Among 30 antibiotic r esistant S . Enteritidis, 2 1 isolates(70 %) were phage type 2 1, 8 i solates(26.7%) were phage t ype 2 3 and 1 isolate( 3.3%) was RDNC, respectively. Of the phage types observed, all of phage type 23(8 isolates) were nalidixic acid resistant and phage type 21 were AM-TIC-SM-CM multi-resistance(13 isolates; 43.3%), AM-TIC-SM-TE(4 isolates; 13.3%), AM-TIC-SM(1 isolate; 3.3%), AM-TIC-CM(1 isolate; 3.3%), and AM-TIC(2 isolates; 6.7%) resistance and 1 isolate of RDNC was NA-TE resistance. PFGE divided the isolates into two major clusters, A(n=14) and B(n=14). There were four different resistance profiles with resistance to AM, TIC, SM, TE, NA within PFGE A. Also resistance to AM, TIC, SM, CM was common within PFGE B. The PFGE A strains typed as PT21(n=5), PT23(n=8), and RDNC(n=1), While all the PFGE B strains typed as PT21(n=14). In consequence, there was the highly significant concurrence between resistance typing, phage typing and PFGE.

In order to investigate the resistance patterns and molecular characteristics of resistance gene of 9 NA-resistant Salmonella enterica subsp. enterica serovar Enteritidis, Total of 101 isolates were isolated from stool sampes from 2005 to 2006. Among them, 48 isolates(47.5%) were identified S. Enteritidis, 24 isolates(23.8%) S. Typhi, 8 isolates(42.5%) S. Typhimurium, 7 isolates(6.9%) S. Paratyphi A and 14 isolates (13.9%) others Salmonellas. All of S. Enteritidis were resistant to ampicillin(43.8%), ticarcillin(43.8%), streptomycin(37.5%), chloramphenicol(29.2%), tetracycline(10.4%) and nalidixic acid(18.8%), respectively. All nalidixic acid-resistance isolates represented one point mutation in the quinolone resistance determining region(QRDR) of gyrA gene. Among them, 8(89%) isolates were substituted Tyr for Ser at position amino acid 83th or 1(11%) isolate was substituted Asn for Asp at position amino acid 87th. In consequence, Continued surveillance of NA-resistance among non-Typhi S. entetica isolates is needed to mitigate the increasing prevalence of nalidixic acid resistance.