목적 : Coagulase-negative Staphylococci 분리 균주에 대한 quinolone 계열 및 그람양성균에 효과적인 vancomycin과 erythromycin 항생제 감수성 정도를 알아보고 DNA gyrase 유전자를 분석하고자 한다. 방법 : 세균성 각막염이 의심되는 사람의 각막에서 검출한 Coagulase-negative Staphylococci 6 균주를 대상으로 ofloxacin, ciprofloxacin, levofloxacin, vancomycin, erythromycin 항생제 감수성을 실시한 후 각 균주들의 genomic DNA를 추출하여 PCR 증폭한 후 gyraseA 유전자의 DNA를 분석하였다. 결과 : 항생제 감수성 검사에서 S. epidermidis (SE-2, SE-3), S. hominis (SH-1) 그리고 S. saprophyticus (SS-1) 균주에서는 ofloxacin, ciprofloxacin, levofloxacin, vancomycin 감수성, erythromycin 내성으로 나타났으며, 나머지 균주에서는 모두 감수성으로 나타났다. gyraseA 유전자 분석에서는 S. epidermidis (SE-1) 균주에서 Met75→Thr, Met93→Val 으로 아미노산 이중 mutation이 관찰되었으며, S. warneri (SW-1)와 S. saprophyticus (SS-1) 균주에서는 다수의 silent mutation이 관찰되었다. 결론 : Coagulase-negative Staphylococci 분리균주에서 erythromycin 항생제의 내성이 있다는 것을 확인 할 수 있었으며, gyraseA 유전자 분석결과 아미노산 이중 mutation 및 silent mutation이 관찰되었다. 따라서 지금은 내성이 아니지만 silent mutation이 언제든지 내성을 일으킬 수 있을 것으로 생각된다.

The dental infections have been increased due to the widespread overuse and exposure to antibiotics. One of the well-known pathogens is S. aureus The pathogenic properties of S. aureus is associated with the virulence gene. The objective of this study is to investigate the distribution of virulence gene of S. aureus which may contribute to the prevention and treatment of bacterial infections. 54 strains of S. aureus were separated from saliva taken from 129 outpatients diagnosed with periodontitis from Jun. to Dec., 2010 in Seoul. 44 (46.6%) and 13 (31.7%) strains of them were obtained from 88 and 41 outpatients from the S and E dental clinics, respectively. Then, the distribution of virulence gene and genetic diversity were analyzed with the PCR technique. The result of the S. aureus isolates possessed coagulase gene and showed six polymorphism types 390~470 bp (1.8%), 550~633 bp (3.7%), 630~714 bp (9.3%), 715~795 bp (20.4%), 796~876 bp (40.7%) and 877~957 bp(22.2%) due to variable numbers of tandem repeats present within the gene. In this study it will be anticipated that this study can contribute to establish efficiently the countermeasure about the prevention and treatment of antibiotic bacterial infections.

To determine current rate of antimicrobial resistance, a total of 236 isolates from milk samples of dairy cattle with mastitis in Korea during 2010-2011 were examined against 12 antimicrobials using disc diffusion method: 67 Staphylococcus aureus, 74 coagulase-negative Staphylococcus spp. (CNS), and 95 Escherichia coli isolates. The isolates examined in this study were submitted by Local Veterinary Service Laboratories located in 13 provinces and metropolitan cities nationwide. The highest rates of resistance among S. aureus isolates were against ampicillin (56.7%) and penicillin (56.7%), followed by kanamycin (11.9%). All S. aureus isolates were sensitive to lincomycin, amikacin, and cephalothin. Only one isolate showed resistance to tetracycline and oxacillin, respectively. Less than 10% of the S. aureus isolates presented resistance to erythromycin, neomycin, and gentamicin. Among CNS isolates, the most frequently observed resistance was to lincomycin (44.5%), followed by penicillin (28.3%), ampicillin (18.9%), tetracycline (17.5%), kanamycin (13.5%), and erythromycin (9.4%). All or most of the CNS isolates were sensitive to cephalothin, amikacin, neomycin, and gentamicin. The highest rate of resistance among E. coli isolates was against tetracycline (26.3%), followed by streptomycin (21%), neomycin (15%), kanamycin (12.6%), and gentamicin (10.5%). Amikacin was the only antimicrobial to which no E. coli isolates showed resistance. Around 10% of the S. aureus isolates and 15% of the CNS isolates showed resistance against three or more antimicrobials simultaneously, while more than 30% of the E. coli isolates did.