Abstract
The emergence of extended spectrum beta-lactamase(ESBL) producing bacteria is causing very serious problems in Korea. Although there have been many reports about these bacteria isolated from patients and clinical specimens, there is no report of ESBL-producing organisms isolated from natural evironment in Korea. This is the first study on the ESBL producing bacteria out of the medical system in Korea. Twenty-six ESBL producing bacteria were isolated only from sewerage plant drain water at Kwang-an beach among the sampling collected sites including snakehead fish plants in Myungi, Aquaculture Engineering Lab. in Pukyong National University and two public-bathrooms in Pusan, Korea. ESBL producing bacteria were identified by double-disk synergy test, conjugation, isoelectric focusing values and PCR. The species of ESBL producing bacteria were Enterobacter cloacae(4 strains), E. sakazakii(8 strains), Klebsiella pneumoniae subsp. pneumoniae(8 strains) and K. pneumoniae subsp. ozaenae(6 strains). TEM and SHV specific PCR products were detected from all the ESBL strains produced TEM+SHV products on the PCR plates. The pI values of ESBL produced by Klebsiella pneumoniae subsp. pneumoniae, K. pneumoniae subsp. ozaenae, Enterobacter cloacae, and E. sakazakii were 5.9, 5.9+5.4; 5.9, $5.9+5.4;{\ge}8.5$, 8.0+5.4, and 8.0+5.4, respectively on the IEF. Seven strains of the isolates were transfered their genes to E. coli RG488 $Rif^r$ by conjugation.
본 논문은 임상검체 이외의 자연계내에서 extended-spectrum $\beta$-lactamase (ESBL) 생성균주의 분리 여부를 확인하고, 분리되었을 경우 이들의 유형을 조사하기 위함이었다. 하수종말처리장, 가물치양식장, 부경대학교 담수어양식장, 공중목욕탕으로부터 분리된 균주를 double disk synergy 검사, 교환접합시험, 등전점 조사 등을 실시하여 하수종말처리장 방류수로붙 extended-spectrum $\beta$-lactamase (ESBL) 생성균주가 26 균주 분리되었다. 균종은 Entero-bacter cloacae와 E. sakazakii, Klebsiella pneumoniae subsp. pneumoniae 및 K. pneumoniae subsp. ozaenae 였다. 이들은 모두 PCR결과 TEM+SHV 복합형이었고 등전점 결과 Klebsiella속의 균들은 pI 5.9, 5.9+5.4 E. cloacae는 $pI{\ge}8.5$, 8.0+5.4, E. sakazakii는 8.0+5.4, 8.0+5.9+5.4였다. 교차접합시험(transconjugation) 결과 피전달 균주인 E. coli RG176 nal$_{r}$에게 K. pneumoniae subsp. pneumoniae (1 균주) K. pneumoniae subsp. ozaenea (5 균주)및 E. cloacae (1 균주)의 $\beta$-lactamase 생성유전자가 전달되었다. 이 결과는 국내에서 임상검체 이외의 자연계에서 분리된 ESBL생성 장내세균의 첫 번째 보고이다.
