• International Journal of Oral Biology
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• 제39권2호
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• pp.81-86
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• 2014

Xylitol is a five-carbon sugar alcohol that inhibits the growth of oral streptococci, including Streptococcus mutans. In this study, we tested xylitol sensitivity among the oral streptococci. We also compared nucleotide homology of putative fructose phosphotransferase system (PTS) and xylitol sensitivity, since xylitol is transported via the fructose PTS. Among the tested Streptococci, S. pneumonia showed the highest resistance to xylitol while S. gordonii and S. sanguinis showed the most sensitive growth inhibition. These streptococci could be grouped according to their xylitol sensitivity. S. mutans and S. salivarius showed similar bacterial growth inhibition by xylitol. S. mitis, S. oralis, S. pneumonia, S. intermedius and S. anginosus showed relatively low sensitivity to xylitol. When the genetic homologies of five fructose PTSs were compared among the tested streptococci, closely related streptococci showed similar sensitivity to xylitol. Taken together, fructose PTSs may mediate the sensitivity to xylitol in oral streptococci.

• Journal of Microbiology and Biotechnology
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• 제32권10호
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• pp.1234-1244
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• 2022

Oral streptococci are considered as an opportunistic pathogen associated with initiation and progression of various oral diseases. However, since the currently-available treatments often accompany adverse effects, alternative strategy is demanded to control streptococci. In the current study, we investigated whether short-chain fatty acids (SCFAs), including sodium acetate (NaA), sodium propionate (NaP), and sodium butyrate (NaB), can inhibit the growth of oral streptococci. Among the tested SCFAs, NaP most potently inhibited the growth of laboratory and clinically isolated strains of Streptococcus gordonii under anaerobic culture conditions. However, the growth inhibitory effect of NaP on six different species of other oral streptococci was different depending on their culture conditions. Metabolic changes such as alteration of methionine biosynthesis can affect bacterial growth. Indeed, NaP enhanced intracellular methionine levels of oral streptococci as well as the mRNA expression level of methionine biosynthesis-related genes. Collectively, these results suggest that NaP has an inhibitory effect on the growth of oral streptococci, which might be due to alteration of methionine biosynthesis. Thus, NaP can be used an effective bacteriostatic agent for the prevention of oral infectious diseases caused by oral streptococci.

• International Journal of Oral Biology
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• 제39권1호
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• pp.9-13
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• 2014

Streptococci are among the normal human microflora that populate the oral cavity. However, oral streptococci are known as a major causative agent for dental caries and bacterial endocarditis. Tetracycline is a broad-spectrum antibiotic that is used for oral infections but two mechanisms of tetracycline resistance in streptococci have been reported. The tet(K) and tet(L) genes in these bacteria are related to the active efflux of tetracycline, whereas tet(M) and tet(O) confer ribosomal protection from this antibiotic. It has been reported that the tetracycline resistance of streptococci is related mainly to the activity of tet(M) and tet(O). In our present study, we examined the prevalence of tet(M) and tet(O) in oral streptococci isolated from Korean dental plaques using PCR. One hundred and forty eight of 635 isolates (23.3%) were tetracycline resistant; 68 of these strains (46%) harbored tet(M) and 3 strains (2%) were positive for tet(O). However, tet(M) and tet(O) did not co-exist in any of the resistant strains. Seventy seven of the 148 tetracycline resistant strains (52%) were negative for both the tet(M) and tet(O) genes.

• Restorative Dentistry and Endodontics
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• 제29권5호
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• pp.462-469
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• 2004

The aim of this study was to investigate the susceptibility of mutans streptococci (S. mutans and S. sobrinus) and Streptococcus anginosus, for seven antibiotics, penicillin G, amoxicillin, ciprofloxacin, cefuroxime, erythromycin, bacitracin, and vancomycin. The minimum inhibitory concentration (MIC) of seven antibiotics against 3 species (type strains) of mutans streptococci and S. anginosus, 10 strains (wild type) of S. mutans, 7 strains (wild type) of S. sobrinus, and 11 strains (wild type) of S. anginosus, were measured by broth dilution method. All of the type strains of mutans streptococci and S. anginosus had the same susceptibility for penicillin G, amoxicillin, cefuroxime and bacitracin. Type strain of S. anginosus was sensitive in ciprofloxacin, but those of mutans streptococci were not. All of the clinical isolates of mutans streptococci and S. anginosus had the same susceptibility for the seven antibiotics. Our data reveal that mutans streptococci and S. anginosus have similar antibiotic-resistant character. In addition. these results may offer the basic data to verify the antibiotic-resistant mechanism of mutans streptococci and S. anginosus.

• 대한소아치과학회지
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• 제31권4호
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• pp.579-586
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• 2004

본 연구의 목적은 chlorhexidine(Cervitec)과 fluoride(Fluor-protector) 성분을 각각 포함한 varnish를 치아에 적용하였을 때 타액내의 mutans streptococci의 수의 감소에 미치는 효과를 알아보기 위한 것이다. 전북대학교 치과대학생 40명을 대상으로 하여 mutans streptococci 균종 수를 평가하였으며, 이들을 무작위로 네 군으로 나누어 다음과 같이 varnish를 적용하였다; A) varnish를 적용하지 않은 군(n=10), B) chlorhexidine varnish 적용군(n=10), C) fluoride varnish 적용군(n=10), D) chlorhexidine과 fluoride varnish를 모두 적용한 군(n=10). Mutans streptococci 수 측정에는 Orion diagnostica 사의 Dentocult SM을 사용하였다. Varnish를 적용하지 않은 상태에서 1차로 mutans streptococci 수를 측정한 후 각각의 varnish를 적용하였으며, varnish 적용 12주 후 다시 측정하여 기록하였다. 모든 실험군(group B, C, D)에서 12주 후에 측정한 mutans strepococci 수가 감소한 개체가 증가한 개체보다 많았으나 통계적으로 유의한 차이는 보이지 않았다(p>0.05). 실험에 사용된 어떠한 varnish도 적용 12주 후에 타액 내 mutans streptococci 수에 통계적으로 유의할 만한 변화를 주지는 못하는 것으로 나타났다(p>0.05).

• International Journal of Oral Biology
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• 제36권4호
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• pp.163-166
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• 2011

Oral viridans streptococci are recognized as one of the etiological agents of a variety of infectious diseases such as dental caries and infective endocarditis. Although antimicrobial susceptibility tests for these fastidious bacterial species are now established and standardized, a comparison between the broth microdilution and broth macrodilution tests has not previously been performed. This comparison was performed in the present study using the tests adopted by the Clinical and Laboratory Standards Institute (CLSI) and seven clinical isolates of oral viridans streptococcal strains. A modified broth macrodilution susceptibility test method was also included in this analysis, in which the media was not supplemented with horse blood. The susceptibility interpretation category agreements were measured at 83% (broth microdilution versus broth macrodilution) and 71% (broth microdilution versus modified broth macrodilution). The interpretation category agreement between the broth macrodilution and modified broth macrodilution tests was also 83%. These data indicate that the interpretation of antibiotic susceptibility test results for oral viridans streptococci are influenced by the methods used.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제30권3호
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• pp.211-217
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• 2004

Previously, strains of Streptococci genera were isolated from osteomyelitis caused by the post-infection after extraction. In present study, to test the sensitivity of the Streptococci strains against seven antibiotics, penicillin G, amoxicillin, tetracycline, ciprofloxacin, cefuroxime, erythromycin, clindamycin, and vancomycin, minimum inhibitory concentration (MIC) was performed using broth dilution assay. Our data showed that the value of MIC of the Streptococci against antibiotics were different among the strains. In addition, the degree of resistance to antibiotics of Streptococci strains was mainly depended on the origin of isolation. Our results suggest that the development of the rapid and accurate method to detect the antibiotics-resistant bacteria is need to prevent the misuse or abuse of antibiotics and outbreak of antibiotics-resistant bacteria.

• International Journal of Oral Biology
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• 제33권4호
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• pp.197-203
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• 2008

It has been reported that the antimicrobial susceptibility patterns of viridans streptococci vary according to geographical region. Although several studies on the antibiotic resistance of viridans streptococci in foreign countries have been reported, little is known about the distribution of resistance among viridans streptococci in Korea. In this study, 88 isolates of viridans streptococci from Korean students' dental plaque were identified as 12 different species. The susceptibility of these isolates to 8 antibiotics was investigated. The in vitro antibiotic activity of penicillin G, ampicillin, vancomycin, streptomycin, gentamicin, erythromycin, amoxicillin, and tetracycline was measured by the broth microdilution method. The range of the minimum inhibitory concentrations (MIC), MIC50, MIC90, and the percentage of the susceptible isolates were determined. Streptococcus mutans and Streptococcus salivarius were susceptible to the 8 antibiotics. Isolates with resistance to vancomycin, streptomycin, and amoxicillin were not found. The overall resistance rates of the 88 isolates to penicillin G, ampicillin, gentamicin, erythromycin, and tetracycline were 12.5%, 62.5%, 62.5%, 26.1%, and 26.1%, respectively.

• 대한소아치과학회지
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• 제31권3호
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• pp.439-447
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• 2004

한국인 소아의 치면세균막에 존재하는 mutans streptococci종 및 생물형의 발현빈도와 치아우식경험지수와 상관관계를 알아보기 위하여, 조선대학교 치과병원에 내원한 12세 미만 113명의 소아 환자의 치아우식경험지수를 구하고, 이들의 상하 악 유전치 및 유구치의 협면 및 설면의 치면세균막 샘플을 채취하여 mutans streptococci를 mitis-salivarius bacitracin 배지에서 선택적으로 분리하였다. 이들의 biotype을 알아보기 위해 생화학적 검사를 실하였고, 이들의 종 수준에서의 동정을 위해 dextranase 유전자를 표적으로 하는 중합효소연쇄반응을 시행하여 하였다. 113명의 환자 중에서 40명의 치면세균막에서 40 균주의 mutans streptococci이 검출되었다. 이들 중 생물형 제 I 형(45%)이 가장 많이 검출되었으며, 그 다음으로 제 IV 형(32.5%), 제 II 형(15%), 제 V 형(5%) 제 III 형(2.5%) 순으로 검출되었다. 또한, 종 수준에서의 발현빈도를 알아본 결과 S. mutaus가 69%, S. sobrinus는 31%였다. Mutans streptococci 종 또는 생물형에 따른 환자의 치아우식경험지수간의 차이는 없는 것으로 조사되었다(p>0.05). 이상의 결과를 종합할 때, 한국인의 소아의 구강 내에 존재하는 mutans streptococci중 생물형 제 I 형인 S. mutans가 가장 높은 빈도로 존재하며, 치아우식증이 세균학적 요소만이 아닌 기타 여러 원인요소에 의해 발병되는 다른 여러 연구 결과와 일치함을 알 수 있었다.

• International Journal of Oral Biology
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• 제30권4호
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• pp.125-130
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• 2005

Thrombin-induced platelet microbicidal proteins (tPMP) are antibacterial proteins released when platelets are stimulated by thrombin. It has been reported that tPMP has antibacterial activity against various bacterial species including causative agents of infective endocarditis. Most of the oral streptococci have resistance to the killing by tPMP and this fact may play an important role as a virulence factor in infective endocarditis. However, the susceptibility and resistance mechanism of oral streptococci for tPMP have not been revealed yet. In this study, the killing mechanism of tPMP for oral streptococci has been investigated. Streptococcus rattus BHT, a susceptible strain, and Streptococcus gordonii DL1, a resistant strain, have been used in this study. tPMP was isolated from platelet after stimulation with thrombin. Cell membrane depolarization was examined with 3,3'-dipropylthiodicarbocyanine iodide ($DiSC_3$), membrane potential-sensitive cyanine dye, by fluorescence spectrophotometry. The permeabilization of cell membrane by tPMP was investigated with propidium iodide (PI) by flow cytometry. tPMP susceptible S. rattus BHT showed the increase of the $DiSC_3$ fluorescence level meaning depolarization of cell membrane and increase of the uptake of PI which means permeabilization of cell membrane. However, tPMP resistant S. gordonii DLI did not show depolarization and permeabilization. These results indicate that the increasing depolarization and permeabilization of oral streptococcal cell membrane are associated with the bactericidal activity of tPMP.