• Journal of Animal Science and Technology
• /
• 제66권1호
• /
• pp.57-78
• /
• 2024

In a global context, bacterial diseases caused by pathogenic bacteria have inflicted sustained damage on both humans and animals. Although antibiotics initially appeared to offer an easy treatment for most bacterial infections, the recent rise of multidrug-resistant bacteria, stemming from antibiotic misuse, has prompted regulatory measures to control antibiotic usage. Consequently, various alternatives to antibiotics are being explored, with a particular focus on bacteriophage (phage) therapy for treating bacterial diseases in animals. Animals are broadly categorized into livestock, closely associated with human dietary habits, and companion animals, which have attracted increasing attention. This study highlights phage therapy cases targeting prominent bacterial strains in various animals. In recent years, research on bacteriophages has gained considerable attention, suggesting a promising avenue for developing alternative substances to antibiotics, particularly crucial for addressing challenging bacterial diseases in the future.

• 환경생물
• /
• 제26권3호
• /
• pp.240-246
• /
• 2008

한강유역 4개 정점으로부터 46주의 Enterococcus 속 세균을 분리하였으며 이 세균은 E. faecium 15주, E. casseliflavus 26주, E. facecalis 1주 및 E. hirae 4주로 이루어져 있었다. Streptomycin의 경우 조사대상 균주 40주 중 45주의 세균이 내성을 나타내었으며 tetracycline과 quinupristin/dalfopristin의 경우 각각 21주 및 19주의 세균이 내성을 나타내었다. 한편 gentamicin과 vancomycin의 경우에는 각각 15주 및 2주의 세균이 내성을 나타내었다. 분리된 Enterococcus 속 세균 46주 중 39주가 2가지 이상의 항생제에 대하여 내성을 나타내었으며, 이 세균 중 10주는 5가지 이상의 항생제에 매하여 모두 내성을 가지는 것으로 조사되었다. 특히 정점 C인 안양천에서 분리된 균주는 8가지의 항생제에 대하여 모두 내성을 나타내었다. 조사 정점이 한강 하류로 내려갈수록 다제 내성 균주가 분리되는 빈도수가 증가하는 추세를 나타내었다. 디스크확산법으로 항생제 내성 세균의 MIC값을 측정한 결과 streptomycin에 최대 4,096 ${\mu}g$ mL$^{-1}$의 MIC를 나타낸 균주가 16주이었으며 gentamicin의 경우에도 최대 MIC가 2,048 ${\mu}g$ mL$^{-1}$을 나타낸 균주가 17주이었다. 한편 vancomycin에 대하여는 최대 512 ${\mu}g$ mL$^{-1}$의 MIC값을 나타내는 균주가 1주이 었으며, quinupristin/dalfopristin과 tetracycline에 대하여는 각각 64 ${\mu}g$ mL$^{-1}$의 농도에 내성을 가진 균주가 각각 2주와 33주이었다. 분리한 세균의 vancomycin 및 quinupristin/dalfopristin에 대한 MIC값을 임상에서 분리한 세균의 MIC간과 축산농가에서 분리한 세균의 MIC값을 상호 비교하였을 때 한강 수계에서 분리된 이들 항생제에 대하여 내성을 나타내는 세균은 축산 폐수로부터 유래된 것으로 유추되었다.

• Journal of Microbiology
• /
• 제39권1호
• /
• pp.62-66
• /
• 2001

Unlike eukaryotic efflux pumps energized by ATPase bacterial efflux pumps are energized by the proton motive force. That is the reason why CCCP, an inhibitor of proton motive forcer is widely used to study the bacterial efflux pump. In many cases, efflux systems have been observed only in quinolone-resistant bacteria. Most of the quinolone-susceptible strains have been found to maintain little efflux pump. However some susceptible bacteria skewed the increased intracellular quinolone concentration only at a low concentration (0.01 or 0.1 mM) but net at a high concentration (1 mM) of CCCP. If bacterial cells were killed at high concentrations of CCCP and lost the integrity of their membranes, the intracellular quinolone would leak out from cells with no efflux system. The efflux pump system in the quinolone-susceptible strains could net be detected at the same concentration used for resistant bacteria. To test this hypothesist the intracellular quinolone concentration in the quinolone-susceptible and -resistant strains of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus was assayed at various concentrations of CCCP. Since the effect of CCCP is very rapid, the survival of bacteria was observed by assaying the DNA synthesis in 5 min. In the case of E. coli, but not P. aeruginosa or S. aureus, the quinolone susceptible strain was more susceptible to CCCP than the quinolone resistant ones, especially when the incubation with CCCP was extended. Decrease of the intracellular quinolone concentration resulted in a false result-no or weak efflux system in the quinolone susceptible strains. Results suggested that the concentration of CCCP should be optimized in order to detect the efflux system in the quinolone susceptible strains of E. coli.

• 미생물학회지
• /
• 제20권1호
• /
• pp.11-20
• /
• 1982

A study was undertaken to examine the effect of curing agents on the stability, curing and segregation of R plasmid pSL100. And also the stability, transfer frequency, and recombination of its segregants obtained from curing agent treatment were studied. Ethidium bromide, acridine orange, and mitomycin-C were used as curing agent. The results obtained were as follows ; 1. The curing agent ethidium bromide, acridine orange, and mitomycin-C were not effective for curing the multiple antibiotic resistant determinant of pSL100 in Salmonella typhimurium and Escherichia coli. However, they induced plasmid segregation with high frequency in S.typhimuruim LT-2strains. TcApSmCm, TcSmCmKm, TcApCm, TcAp, TcKm, Tc segregants were obtained. 2. The resistant markers of the segregents were transferred to S.typhimurium LT-2 strains with high frequencies whereas they were transferred to E.coli K-12 only with low frequencies. 3. The transconjugants obtained from conjugation between two different S.typhimurium segregants were similar to the phenotype of the original R factor pSL100 and the resistant markers were transferred to the S.typhimurium LT-2 or E.coli strain with equal frequencies, indicating that they are recombinants. 4. The transconjugants obtained from conjugation between pSL100 segrgants and pKM101, or pBR322 possessed the resistant markers of the two parental plasmids and they were transferred to both S.typhimurium and E.coli K-12 strains with the same frequencies and maintained stably, suggesting that they are also recombinants. 5. The recombinant pSL100 could be also obtained in rec A-strains of E.coli, suggesting that the gene function of rec A is required for the recombination of pSL100 segregants in E.coli.

• 대한수의학회지
• /
• 제43권1호
• /
• pp.103-112
• /
• 2003

A multiplex PCR assay, which allows simultaneous detection of vancomycin resistant genotypes and Enterococcus species-specific genes, was developed. Vancomycin resistant enterococci (VRE) from chickens and humans could be detected for vanA, vanB, vanC-1, vanC-2, $ddl_{E.faecium}$ and $ddl_{E.faecalis}$ by multiplex PCR. Eight isolates of VRE from humans (n=11) had $ddl_{E.faecium}$ and vanA, and 3 isolates of the VRE had $ddl_{E.faecium}$ and vanB. One isolate of VRE from chickens (n=6) had $ddl_{E.faecium}$ and vanA, and 5 isolates of the VRE had only vanA. E. faecium, E. faecalis, E. gallinarum and E. casseliflavus were also confirmed for the species-specific gene by multiplex PCR. This multiplex PCR could detect E. faecium, E. faecalis, E. gallinarum, E. casseliflavus, vanA, vanB, vanC-1 and vanC-2, simultaneously. The PCR assay established in the present study can be an alternative to time-consuming biochemical tests and antibiotic susceptibility tests of Enterococcus spp.

• Bulletin of the Korean Chemical Society
• /
• 제32권8호
• /
• pp.2695-2699
• /
• 2011

${\beta}$ Ketoacyl acyl carrier protein synthase III (KAS III) initiates fatty acid synthesis in bacteria and is a key target enzyme to overcome the antibiotic resistance problem. In our previous study, we found flavonoid inhibitors of Enterococcus faecalis KAS III and proposed three potent antimicrobial flavonoids against Enterococcus faecalis and Vancomycin-resistant Enterococcus faecalis with MIC values in the range of 128-512 ${\mu}g/mL$ as well as high binding affinities on the order from $10^6$ to $10^7\;M^{-1}$. Using these series of flavonoids, we conducted biological assays as well as docking study to find potent flavonoids inhibitors of Staphylococcus aureus KAS III with specificities against Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus. Here, we propose that naringenin (5,7,4'-trihydroxyflavanone) and eriodictyol (5,7,3',4'-tetrahydroxyflavanone) are potent antimicrobial inhibitors of Staphylococcus aureus KAS III with binding affinity of $3.35{\times}10^5$ and $2.01{\times}10^5\;M^{-1}$, respectively. Since Arg38 in efKAS III is replaced with Met36 in saKAS III, this key difference caused one hydrogen bond missing in saKAS III compared with efKAS III, resulting in slight discrepancy in their binding interactions as well as decrease in binding affinities. 4'-OH and 7-OH of these flavonoids participated in hydrogen bonding interactions with backbone carbonyl of Phe298 and Ser152, respectively. In particular, these flavonoids display potent antimicrobial activities against various MRSA strains in the range of 64 to 128 ${\mu}M$ with good binding affinities.

• 한국습지학회지
• /
• 제13권1호
• /
• pp.117-127
• /
• 2011

본 연구의 목적은 하수처리장의 공간적 그리고 운전인자에 따른 테트라싸이클린 내성균(TRB) 및 테트라싸이클린 내성 유전자(TRG)들의 거동을 파악하는데 있다. 이를 위한 노력으로, 세 개의 실제 다른 하수처리장내에서 7개월 이상 각각의 반응조별로 시료를 채취하여 TRB 및 TRG가 분석되었다. 통계 기법은 주성분분석(PCA)을 통해 이들 간에 어떠한 일반적 관계식이 성립하는지 알아보려 노력하였다. 통계 분석결과, 활성슬러지내에 TRB 농도는 1차 침전 유입수에 있는 TRB 농도에 많은 영향을 받는 것을 알 수 있었다. 또한, 본 연구를 통해 TRB와 TRG의 내거동이 하수처리장 SRT 조건에 많이 영향을 받는 것을 알 수 있었다.

• 미생물학회지
• /
• 제47권4호
• /
• pp.381-385
• /
• 2011

Methicillin-resistant Staphylococcus aureus (MRSA)는 화농성 질환, 균혈증을 유발하고 병원내 감염의 주요 원인균으로 알려져 있다. 병원에서의 MRSA 분리율은 점차 증가하여 80% 이상으로 보고 되고 있으며 Methicillin 뿐만 아니라 다른 항균제에도 내성을 나타냄으로 치료를 위한 항균제 사용에 제한을 받고 있다. 이에 본 연구에서는 MRSA의 정확한 판정을 통해 항생제 남용을 막고자 대부분의 병원에서 사용하는 항균제 감수성 검사법과 경제적인 면으로 인해 병원내에서 많이 사용되고 있지 않지만 정확도가 높은 mecA 유전자 검출법을 서로 비교하였다. 그 결과 대조군인 Methicillin-susceptible Staphylococcus aureus와 실험군 MRSA 20 균주를 대상으로 항균제 감수성 검사법과 mecA 유전자 PCR 검출법을 실시한 결과 MRSA 20 균주는 Oxacillin과 Cefoxitin에 모두 내성을 나타냈으나 mecA 유전자 검출에서는 20 개 중 17 개에서만 유전자가 검출되어 염기서열분석 결과 mecA 유전자임을 확인하였다. 이런 결과로 보아 mecA(-) 3 균주는 mecA 유전자의 변이로 추측할 수 있기에 임상에서의 MRSA의 판정은 항균제 디스크법과 mecA 유전자 PCR 검출법을 동시에 사용함으로 정확한 MRSA 진단에 도움을 주고자 한다.

• Urogenital Tract Infection
• /
• 제13권3호
• /
• pp.72-78
• /
• 2018

Purpose: This retrospective study was undertaken to investigate whether increasing amikacin dosage for ciprofloxacin prophylaxis in patients with fluoroquinolone (FQ)-resistant rectal flora reduce infectious complications after transrectal ultrasound-guided prostate biopsy (TRUSPB). Materials and Methods: A total of 430 patients with FQ-resistant rectal flora based on rectal swab cultures were divided into two groups. Patients in both groups were administered ciprofloxacin (400 mg, intravenous [IV], twice daily) on the same day as TRUSPB and one day after biopsy. However, whereas group 1 patients (n=202) were administered a single injection of amikacin (1 g, IV) one hour before TRUSPB, patients in group 2 (n=228) were administered two injections of amikacin (1 g, IV) before one hour TRUSPB and again on the day after TRUSPB. Results: Of the 430 study subjects, 129 (30.0%) showed extended-spectrum beta-lactamase (ESBL) positivity. The overall incidence rate of infectious complications was 2.8% (12/430). Infectious complication rates were 4.0% (8/202) in group 1 and 1.3% (3/228) in group 2 (p=0.075). Urinary tract infection and acute prostatitis were more frequent in group 1 (3.5% vs. 0.4%, p=0.029). Infectious complication rates in ESBL negative patients were 3.4% (5/145) in group 1 and 1.3% (2/156) in group 2, whereas those in ESBL positive patients were 7.0% (4/57) in group 1 and 1.4% (1/72) in group 2. Conclusions: Increasing the dosage of amikacin for ciprofloxacin prophylaxis reduce infectious complications in patients with FQ-resistant rectal flora and to be more effective in ESBL positive patients with FQ-resistant rectal flora.

• 한국토양비료학회지
• /
• 제29권2호
• /
• pp.190-198
• /
• 1996

Bradyrhizobium japonicum RJB6$str^rnal^r$에 neomycin resistant gene인 Tn5을 삽입한 표지균주를 사용하여 Pseudomonas fluorescens(PS-3)와 Bacillus subtilis(BCAC-4)를 대두에 혼합접종하고, 또한 항생제 처리후 표지균주를 접종한 대두의 생장 및 근류형성율을 조사 분석한 결과를 요약하면 다음과 같다. 1. 5년이상 대두 재배토양에 표지균주인 RJB6 $str^rnal^rneo^r$을 Ps-3와 혼합접종했을 때 접종근류균의 근류형성율은 8.5%, BCAC-4와 혼합접종한 경우는 4.3%였으나, 표지균주, Ps-3라 BCAC-4의 3 균주를 혼합접종했을 때는 2.9% 에 지나지 않았다. 2. 대두를 재배하지 않은 토양에 표지균주을 Ps-3와 혼합접종했을 때 접종근류균의 근류형성은 10.3%, BCAC-4와 혼합접종한 경우은 6%였으며, 표지균주와 Ps-3, BCAC-4의 3 균주를 혼합접종 했을 때 5.0%의 근류형성율을 나타냈다. 3. 혼합접종이 대두 생육상에 미치는 영향은 일반적으로 표지균주와 Ps-3의 혼합접종 처리구에서 가장 양호했다. 4. 항생제를 처리했을 때 5년 이상 대두재배 토양에서 접종근류균의 근류형성은 12.2-25.4% 였으며, 대두를 재배하지 않은 토양에서는 23.7-43.7% 였으나, 항생제 1,000ppm 처리구 에서 43.2%로 가장 높은 근류형성율을 보였다.