• Journal of Dairy Science and Biotechnology
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• 제39권3호
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• pp.104-112
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• 2021

This study was conducted to evaluate the efficacy of commercial disinfectants at inactivating Enterobacter sakazakii (Cronobacter spp.) in water. Disinfectant I contained 6.15% sodium hypochlorite, and disinfectant II contained both 2.25% n-alkyl dimethylbenzyl ammonium chloride and 2.25% n-alkyl ethylbenzyl ammonium chloride. Disinfectant I was added to distilled water to obtain a range of residual chloride concentrations at 50 ppm intervals with a maximum of 1-1,000 ppm. Disinfectant II was prepared at concentrations ranging from 1-200 ppm with 5 ppm intervals. Exposure time for all solutions was 10 min. In total, 58 E. sakazakii (Cronobacter spp.) strains were tested in this study. Nine isolates were obtained from clinical samples, and 49 isolates were obtained from environmental samples. Seven strains (6 clinical and 1 environmental) were able to survive in 100 ppm disinfectant I, and a maximum of 5 ppm of disinfectant II. Fifty one strains (3 clinical and 48 environmental) were not killed in 10 ppm of disinfectant I and 1 ppm of disinfectant II in water. In conclusion, this study demonstrated that clinical E. sakazakii (Cronobacter spp.) strains displayed 5- to 10-fold higher resistance to disinfectants than environmental E. sakazakii (Cronobacter spp.) strains. Disinfectant II, containing quaternary ammonium compounds, was shown to be more potent in inactivating E. sakazakii (Cronobacter spp.) in water used to clean infant formula manufacturing equipment than disinfectant I.

• Journal of Dairy Science and Biotechnology
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• 제41권3호
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• pp.103-112
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• 2023

This study aimed to assess the effectiveness of 10 different pre-enrichment methods using Real-Time polymerase chain reaction (PCR) in support of the FDA method. When the initial Cronobacter spp. (Enterobacter sakazakii) inoculation was 7.2 CFU/g, the Ct values were observed in the following order: 21.37 (Enterobacteriaceae enrichment [EE] broth), 21.95 (brain heart infusion [BHI]), 22.72 (tryptic soy broth [TSB]), 23.02 (violet red bile lactose [VRBL]), 22.31 (TSB-0.1% sodium pyruvate [SP]), 23.43 (distilled water [DW]), 24.34 (phosphate buffered saline [PBS]), 24.95 (nutrient broth [NB]), 25.82 (TSB-0.6% yeast extract [YE]), and 28.27 (violet red bile glucose [VRBG]). For an inoculation of 1.82% CFU/g of Cronobacter spp. (E. sakazakii), the Ct values were recorded in this sequence: 20.34 (EE broth), 22.16 (TSB-0.6% YE), 22.37 (BHI), 22.71 (VRBL), 22.88 (TSB), 23.01 (DW), 23.19 (NB), 23.79 (TSB-0.1% SP), 24.66 (VRBG), and 24.70 (PBS). Finally, when the inoculum of Cronobacter spp. (E. sakazakii) was 0.182 CFU/g, the Ct values followed this order: 21.93 (VRBL), 23.07 (TSB-0.6% YE), 23.31 (DW), 23.47 (PBS), 23.70 (BHI), 24.14 (TSB-0.1% SP), 25.14 (TSB), 29.00 (VRBG), 31.55 (EE broth), and were undetected in the case of NB. Consequently, these results indicate that there were no significant differences among the 10 different pre-enrichment broths. Future studies should focus on exploring pre-enrichment broths that can improve the limit of detection at very low Cronobacter spp. (E. sakazakii) concentrations and enhance the selective recovery of Cronobacter spp. (E. sakazakii) under acid, antibiotic, cold, and heat damage conditions.

• 한국축산식품학회지
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• 제28권1호
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• pp.99-104
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• 2008

소 장관으로부터 분리한 유산균 중에서 Enterobacter sakazakii에 생육저해활성을 나타내는 균주를 분리한 후 동정한 결과 Enterococcus faecium으로 동정되었고 E. faecium JH95로 명명하였다. 본 균주는 kanamycin과 streptomycin에 대해 $100{\mu}g/mL$가지 매우 높은 내성을 나타내었다. 본 균주의 배양액은 L. monocytogenes, C. perfringens와 E. sakazakii에 대하여 높은 항균 활성을 나타내었으며, S. typhimurium, S. aureus와 E. coli O157:H7에 대해서도 항균활성을 나타내었다. 본 균주의 배양 상등액은 항균활성을 보이지 않았으며, 배양액이 지니고 있는 항균활성은 $100^{\circ}C$에서 5분간 가열하거나 단백질 가수분해효소 처리에 의해 소실되어 식중독 미생물에 대한 생육저해물질이 단백질인 것으로 추정되었다.

• Food Science and Biotechnology
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• 제17권4호
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• pp.861-864
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• 2008

Enterobacter sakazakii, Salmonella typhimurium. and Bacillus cereus were evaluated on inoculated infant formula by gamma irradiation treatment as a method to provide microbial safety. The infant formula inoculated with the major pathogenic bacteria was treated at irradiation dose of 0, 3, 5, and 10 kGy, respectively. After treatment, the samples were individually packaged and stored at $20^{\circ}C$. Microbiological data during storage represented that the populations of E. sakazakii, S. typhimurium, and B. cereus were reduced with the increase of irradiation dose by 4 to 5 log reductions. In particular, E. sakazakii, S. typhimurium. and B. cereus were eliminated at 10, 5, and 3 kGy, respectively. E. sakazakii was the most radiation-resistant, while B. cereus was the least. Our results represent that gamma irradiation below 10 kGy should eliminate the growth of the major pathogenic bacteria in infant formula during storage.

• Food Science and Biotechnology
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• 제18권6호
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• pp.1537-1540
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• 2009

Enterobacter sakazakii is a representative microorganism whose presence in infant foods can cause serious disease. The purposes of this study were to determine the inactivation effects of intense pulsed light (IPL) on E. sakazakii and the commercial feasibility of this sterilization method. The inactivation of E. sakazakii increased with increasing electric power and treatment time. The cells were reduced by 5 log cycles for 4.6 and 1.8 msec of treatment at 10 and 15 kV of electric field strength, respectively. The sterilization effects on commercial infant foods were investigated at 15 kV. The cell population in an infant beverage, an infant meal, and an infant powdered milk product inoculated with E. sakazakii were inactivated exponentially as a function of time and reduced by 4.0, 2.5, and 1.5 log cycles for 9.4, 7.0, and 7.0 msec of treatment time, respectively.

• Food Science and Biotechnology
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• 제16권6호
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• pp.948-953
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• 2007

The powdered cereal sunsik is a partially thermal-processed product that required safety evaluations for food-borne pathogens. Thirty-six sunsik products from Korean markets were collected and analyzed for contamination by total viable cell counts, coliforms, Escherichia coli, and the spore-forming Clostridium perfringens and Bacillus cereus. Enterobacter sakazakii, as a newly emerging pathogen, was also analyzed. Approximately 28% of sunsik were contaminated at 5 log CFU/g for total viable counts. Coliforms and E. coli were detected in 33 and 4% of the samples, respectively. The spore-forming B. cereus was found in 42% of the samples at a maximal level of 3 log CFU/g on average. About 6% the samples were contaminated with Cl. perfringens at an average level of 15 CFU/g. Forty-five % of sunsik contained E. sakazakii, at levels from 0.007 to over 1.1 cell/g by MPN method. In addition, one sunsik product for infants and children showed over 3 log CFU/g for both B. cereus and E. sakazaki. Therefore, concern should be placed on controlling for microbial hazards such as B. cereus and E. sakazakii in sunsik, particularly for the products fed to infants under 6 months of age.

• 한국식품과학회지
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• 제39권3호
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• pp.295-298
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• 2007

본 연구는 쌀가루의 저장온도 및 저장기간에 따른 병원성 미생물 생육특성을 조사하고 안전성과 유효성을 고려한 상업적 열풍 및 마이크로파 처리방법을 사용하여 쌀가루의 미생물학적 안전성, 저장성 및 품질유지를 최적화하고자 하였다. 마이크로파 처리(700 watt/30 sec, MT)와 열풍 처리($65^{\circ}C$/15 min, HT) 후 쌀가루의 처리전과 대비한 색차변화값(${\Delta}E$)은 각각 0.15와 0.27로 측정되어 마이크로파 건조가 열풍 건조보다 색깔의 변화가 적은 것으로 나타났다. B. cereus와 E. sakazakii의 살균력은 MT 처리 후 각각 0.54 log CFU/g, 1.45 log CFU/g으로 감소하여 HT 처리 보다 살균효과가 강하였다. 대조구(NT) 쌀가루의 B. cereus는 4, 10, $20^{\circ}C$ 모든 온도에서 빠른 성장을 보였으나, MT 처리시 성장이 최소화 되었다. E. sakazakii는 4, 10, $20^{\circ}C$ 모든 온도에서 그리고 HT, MT 모든 처리구에서 성장하지 못하였는데, MT 처리시 생존균수가 가장 적었다. 결론적으로 쌀가루의 품질면에서나 미생물학적 안전성 측면에서 마이크로파 처리는 열풍건조 처리를 대체할 수 있는 건조방법으로 평가되었다.

• Food Science and Biotechnology
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• 제14권6호
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• pp.875-877
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• 2005

Presence of Enterobacter sakazakii, occasional pathogen of powdered infant formula causing rare, but life-threatening diseases such as neonatal meningitis, bacteremia, necrotizing enterocolitis, and necrotizing meningoencephalitis after ingestion was examined in 45 powdered infant formula products manufactured in Korea using chromogenic Druggan-Forsythe-Iversen (DFI) medium, and isolates were identified with API 20E. Ent. sakazakii was isolated from three products. Ent. sakazakii isolates were genotyped by RAPD-PCR using two random primers, and their banding patterns were compared.

• 미생물학회지
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• 제37권4호
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• pp.277-283
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• 2001

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.

• 미생물학회지
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• 제48권4호
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• pp.229-239
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• 2012

Cronobacter spp. (formerly Enterobacter sakazakii), a Gram-negative bacillus, is a rare cause of meningitis and central nervous system infections. In England, the first case infected by this organism occurred in 1958. By July 2008, approximately 120 documented cases of Cronobacter spp. infection and at least 27 deaths have been identified from all around the world in the published literature and in reports submitted by public health sectors. In 2007, it was proposed by European organizations that the original taxonomy of E. sakazakii would be revised, to consist of five new species moved to a new genus, and identified as "Cronobacter". E. sakazakii has thus now been reclassified as 6 separate species in the new genus, Cronobacter, gen. nov., within the Enterobacteriaceae family. The new species are presently Cronobacter sakazakii, C. turicensis, C. malonaticus, C. muytjensii, and C. dublinensis; the sixth species is identified simply as genomospecies I, as currently including only two representative strains. The objectives of this review are to provide insight on (1) the classification and taxonomy of Cronobacter spp., (2) its clinical etiology and pathogenicity, (3) prequency of Cronobacter spp. in different categories of ready-to-eat food other than infant formula, (4) methods for detecting, isolating and typing Cronobacter spp., and (5) recent research trends for detecting Cronobacter spp.