Inactivation of Staphylococcus aureus in Oat and Soya Drinks by Enterocin AS‐48 in Combination with Other Antimicrobials

The presence of toxicogenic Staphylococcus aureus in foods and the dissemination of methicillin‐resistant S. aureus (MRSA) in the food chain are matters of concern. In the present study, the circular bacteriocin enterocin AS‐48, applied singly or in combination with phenolic compounds (carvacrol, eugenol, geraniol, and citral) or with 2‐nitro‐1‐propanol (2NPOH), was investigated in the control of a cocktail made from 1 methicillin‐sensitive and 1 MRSA strains inoculated on commercial oat and soya drinks. Enterocin AS‐48 exhibited low bactericidal activity against staphylococci in the drinks investigated when applied singly. The combinations of sub‐inhibitory concentrations of enterocin AS‐48 (25 μg/mL) and phenolic compounds or 2NPOH caused complete inactivation of staphylococci in the drinks within 24 h of incubation at 22 °C. When tested in oat and soya drinks stored for 7 d at 10 °C, enterocin AS‐48 (25 μg/mL) in combination with 2NPOH (5.5 mM) reduced viable counts rapidly in the case of oat drink (4.2 log cycles after 12 h) or slowly in soya drink (3.8 log cycles after 3 d). The same combined treatment applied on drinks stored at 22 °C achieved a fast inactivation of staphylococci within 12 to 24 h in both drinks, and no viable staphylococci were detected for up to 7 d of storage. Results from the study highlight the potential of enterocin AS‐48 in combination with 2NPOH for inactivation of staphylococci.     

低聚糖拮抗食源性致病菌的研究及应用进展

食源性致病菌导致的食品安全问题已成为世界上重要的公共卫生问题之一,寻找高效且安全的天然抑菌剂引起人们的关注。目前有研究表明低聚糖类物质如果胶低聚糖、低聚壳聚糖、褐藻胶低聚糖等具有较好的抑菌效果,并且低聚糖大多来源于植物胶、甲壳动物,天然海藻多糖等自然物质,对环境污染较小;因此低聚糖能够作为潜在的天然抑菌剂被广泛应用在食品行业中,具有一定的研究意义和应用前景,已经逐渐成为食品行业新的研究热点。该研究综述了几种低聚糖对食源性致病菌的抑菌作用,并分析总结了其抑菌机制：一是低聚糖破坏细菌细胞壁和细胞膜,二是渗入细胞内部破坏蛋白质和核酸物质;同时展望了低聚糖在涂膜保鲜和作为食品添加剂两方面的应用,以期为进一步深入研究低聚糖的作用和在食品行业的应用提供理论参考。     

食品生物腐败及新型防腐技术研究进展

概述了食品生物腐败的原因和机理、食源性致病菌的类群和新型杀菌技术在食品防霉防腐领域的研究进展,并展望了新型防腐技术在食品安全生产和品质保证环节的应用前景。     

Evaluation of the Microbial Safety of Child Food of Animal Origin in Greece

Foodborne illness is a major cause of morbidity and mortality especially for children, even in the developed world. The aim of this study was to assess the microbial safety of food of animal origin intended for consumption by children in Greece. Sampling involved 8 categories of retail products and was completed with a collection of 850 samples. These were tested by PCR and/or culture for Listeria monocytogenes, Campylobacter spp., Escherichia coli O157, Salmonella spp., Cronobacter sakazakii, Brucella spp., and Mycobacterium avium subsp paratuberculosis (MAP). The number of positive results recorded collectively for the pathogens under investigation over the total number of samples tested was 3.52% and 0.12% by PCR and culture, respectively. The most frequently detected pathogen was enterohemorrhagic E. coli (1.29%) followed by Brucella (0.82%) and Listeria (0.82%). DNA belonging to MAP was detected in 0.35% of samples, which was also the percentage of positivity recorded for Campylobacter. The percentage for Salmonella was 0.12%. It can be concluded from the results that there is no indication of noncompliance for the tested food samples. However, detection of DNA belonging to pathogens that are transmissible to humans through food is indicative that constant vigilance regarding food safety is an absolute necessity.     

2018—2021年广州市白云区网络外卖食品微生物污染状况监测分析

目的 了解广东省广州市白云区网络外卖食品安全风险,为完善广州市外卖食品安全保障体系提供科学依据。方法 2018—2021年在广州市白云区采集174份网络外卖食品,依据《食品安全国家标准食品微生物学检验》（GB 4789）对样品中菌落总数、大肠埃希菌、沙门菌、金黄色葡萄球菌、单核细胞增生李斯特菌、蜡样芽胞杆菌、副溶血性弧菌进行培养和鉴定。结果 2018—2021年监测样品总体不合格率为20.1%(35/174),其中菌落总数和大肠埃希菌不合格率较高,不同年度的不合格率及不同类别食品的不合格率差异具有统计学意义（P<0.05）。单因素分析发现不同室外湿度、不同食品中心温度样品的合格率组间差异具有统计学意义（P<0.05）。多因素Logistic回归分析发现,食物中心温度越高（OR=0.917,95%CI:0.876～0.960）,食品不合格率越低;对不同品种的外卖食品进行组间比较发现,以米饭加菜类为参照组,凉拌菜类（OR=0.010,95%CI:0.001～0.159）、寿司手卷类（OR=0.041,95%CI:0.002～0.771）的不合格率更低（P<0.05）。结论...     

食品亚硝酸盐来源与检测方法

为正确认识和解决食品中亚硝酸盐残留和超标问题,该文对食品中亚硝酸盐来源、危害及检测技术进行综述。     

Evaluation of Natural Antimicrobials on Typical Meat Spoilage Bacteria In Vitro and in Vacuum-Packed Pork Meat

ABSTRACT: The aim of this study was to investigate the inhibitory effect of natural antimicrobials on the growth of typical spoilage bacteria from marinated pork. Minimum inhibitory concentrations (MIC) of thymol, cinnamaldehyde, allyl isothiocyanate, citric acid, ascorbic acid, a rosemary extract, and a grapefruit seed extract against Lactobacillus algidus, Leuconostoc mesenteroides, Leuconostoc carnosum, Carnobacterium maltaromaticum, Carnobacterium divergens, Brochothrix thermosphacta, and Serratia proteamaculans were determined in a microplate assay. Combinations of antimicrobials were tested and several combinations showed synergistic effects in inhibiting bacterial growth. Single and combined antimicrobials were added to vacuum-packed pork meat to evaluate preserving effects. Antimicrobial concentrations of up to 10 times the MIC values showed no effect on total bacterial growth in vacuum packed pork meaning that although most antimicrobials inhibited the growth of spoilage bacteria in vitro, results from the microplate assay could not be transferred to the meat system. Most natural antimicrobials possess strong odor and flavor that limit their use as a food preservative. In conclusion, this study showed that the use of natural antimicrobials in meat products is limited and that bacterial quality and shelf life was not enhanced under the chosen conditions.     

In vitro Inhibition of Food Spoilage and Foodborne Pathogenic Bacteria by Essential Oil and Leaf Extracts of Magnolia liliflora Desr.

ABSTRACT:  The aim of this study was to examine the chemical composition of the essential oil isolated from the floral parts of Magnolia liliflora Desr. by hydrodistillation, and to test the efficacy of essential oil and various leaf extracts against a diverse range of microorganisms comprising food spoilage and foodborne pathogenic bacteria. The chemical composition of essential oil was analyzed by GC-MS. It was determined that 52 compounds, which represented 78.07% of total oil, were present in the oil. The oil contained mainly levoxine (15.59%), methylcyclopropane (24.26%), 2-β-pinene (5.3%), caryophyllene oxide (4.01%), and β-caryophyllene (1.7%). The oil (1000 ppm/disc) and leaf extracts (1500 ppm/disc) exhibited promising antibacterial effects against the tested pathogens as a diameter of zones of inhibition (9 to 18 and 7 to 12 mm) and MIC values (125 to 1000 and 500 to 3000 μg/mL), respectively. Also, the oil had a potent detrimental effect on the viable count of the tested bacteria. The results obtained in this study support the role of essential oil and the leaf extracts derived from M. liliflora as a remarkable approach to inhibit the growth of food spoilage and foodborne pathogens.     

2016—2020年上海市市售即食食品微生物污染状况分析及评价

目的 了解上海市市售即食食品中微生物污染情况,及时发现食品安全隐患,为即食食品风险评估、管理和标准制定提供科学依据。方法 2016-2020 年共采集上海市即食食品20类共10 521份食品样品,对菌落总数、大肠埃希氏菌计数2种卫生指示菌和副溶血性弧菌、金黄色葡萄球菌、致泻大肠埃希氏菌、沙门氏菌、蜡样芽孢杆菌、单核细胞增生李斯特氏菌（以下简称单增李斯特菌）6种食源性致病菌进行定量或定性检验,并分析卫生指示菌和食源性致病菌污染水平及关联性。结果 凉拌米面制品、沙拉、中式凉拌菜的指示菌污染水平较高,菌落总数均值分别为（5.13±1.43）lgCFU/g、（4.56±1.13）lgCFU/g、（4.26±1.75）lgCFU/g;大肠埃希氏菌计数分别为（1.20±1.00）lgCFU/g、（1.47±1.41）lgCFU/g、（1.18±1.06）lgCFU/g。冷锅串串、沙拉、中式凉拌菜、熟肉制品中单增李斯特菌检出率较高,分别为6.27%、3.36%、2.71%、2.69%;副溶血性弧菌仅在生食动物性水产品（3.65%）、中式凉拌菜（2.58%）、熟肉制品（0.42%）中检出;米面制品中蜡样芽孢杆菌（7.51%）显著高于寿司（0.53%）（P<0.05）。菌落总数均值与大肠埃希氏菌计数均值呈极显著正相关（P<0.001）;菌落总数均值与致病菌样品阳性率呈显著正相关（P<0.05）。结论 上海市生食食物、凉拌、夹心等最后一步加工工艺非加热的即食食品,卫生指示菌和致病菌污染水平较高,食源性致病风险较高,应重点防范。固体即食食品菌落总数计数水平与食源性致病菌污染状况存在相关性。     

2004—2012年分离自北京口岸进出口食品的沙门菌耐药性分析

目的 了解北京口岸进出口食品中分离沙门菌的耐药状况及耐药谱情况,分析耐药趋势,为制定食品安全监管措施和抗生素的使用提供依据。方法 对65株本实验室分离的沙门菌以及17株参比菌株,共82株沙门菌采用Kindy-Bauer(KB)法检测其对15种抗生素的敏感性,根据美国临床实验室标准化研究所(CLSI)标准进行判断,并对药敏试验结果进行数据分析。结果 65株沙门菌分离株除对头孢吡肟、头孢曲松、阿米卡星、头孢噻肟全部敏感外,对其余11种抗生素均有不同程度的耐药,其中氨苄西林耐药率最高为16.9%(11/65),其次为哌拉西林(13.8%,9/65)、四环素(13.8%,9/65)、卡那霉素(9.2%,6/65)和链霉素(7.7%,5/65)。在所有65株沙门菌分离株中,对1种抗生素耐药的菌株共11株,占16.9%(11/65),对2种抗生素耐药的菌株为1株,占1.5%(1/65),对3种及以上抗生素耐药的多重耐药株为7株,多重耐药率为10.8%(7/65)。结论 北京口岸进出口食品中分离的沙门菌对多种抗生素耐药。     

噬菌体在食品安全控制中的研究进展

近年来,噬菌体在食品科学领域中的应用受到国内外研究学者的广泛关注。噬菌体的自身特性表明,其可 作为一种杀菌/抑菌的生物制剂来控制食源性病原菌对食品的污染,是保障食品安全的理想工具。此外,基因工程 技术的发展进一步促进了噬菌体及其产物的安全、高效使用及噬菌体产品的出现。本文就噬菌体在食品安全控制中 的研究进展以及应用前景等方面进行综述。     

百里香酚和肉桂醛联用对沙门氏菌的协同抑菌效应及其应用

研究了百里香酚和肉桂醛联用对沙门氏菌的抑菌效果,并将两者作为复配抗菌剂应用于盐焗鸡中以探究其保鲜效果。采用微量稀释法确定了百里香酚和肉桂醛对沙门氏菌的最小抑菌浓度及联合抑菌效果,结果显示百里香酚和肉桂醛的最小抑菌浓度均为0.25 mg/mL、最小杀菌浓度均为0.5 mg/mL;此外,两者联用时的分级抑菌浓度指数为0.75,表明百里香酚和肉桂醛具有较好的协同抑菌效应;该结论同样被时间-杀菌曲线、扫描电子显微镜、PI染色实验的结果所证实,百里香酚和肉桂醛联用可以显著地破坏沙门氏菌细胞膜的完整性,改变细菌形态,从而导致胞内物质泄漏、最终菌体裂解死亡,表明其具有一定的防腐保鲜应用潜力。因此,该研究以盐焗鸡作为食品模型从微生物和脂质氧化两方面探究了百里香酚和肉桂醛的防腐保鲜效果,结果显示百里香酚和肉桂醛联用可以显著地抑制盐焗鸡中细菌的增殖和脂质的氧化,表明百里香酚和肉桂醛联用可以作为一种天然复配抗菌剂应用于盐焗鸡等熟肉制品的保鲜中。     

Prevalence,Antimicrobial Resistance,and Virulence Characteristics of mecA‐Encoding Coagulase‐Negative Staphylococci Isolated from Soft Cheese in Brazil

Coagulase‐negative staphylococci (CoNS), which are generally neglected as foodborne bacteria, are emerging as significant opportunistic pathogens that may be highly resistant to available antimicrobial drugs. In this study, antimicrobial susceptibility patterns, mecA gene occurrence, and virulence‐associated characteristics were evaluated in CoNS isolated from soft cheese in Brazil. A total of 227 bacterial isolates were recovered from 35 cheese samples belonging to 5 batches with 7 different trademarks. The CoNS counts ranged from 10⁶ to 10⁷ CFU/g. High antimicrobial resistance percentages were observed for oxacillin (76.2%), penicillin (78.5%), erythromycin (67.8%), gentamicin (47.2%), clindamycin (35.7%), rifampicin (26.8%), azithromycin (14.7%), tetracycline (14.7%), levofloxacin (14.2%), and sulfamethoxazole‐trimethoprim (11.9%). A low antimicrobial resistance percentage was observed for chloramphenicol (2.3%), and all of the tested bacteria were susceptible to vancomycin and linezolid. In total, a multiple antibiotic resistance (MAR) index of >0.2 was observed for 80.6% of the isolated CoNS. However, the MAR index ranged from 50% to 92.6% when only bacterial cheese isolates belonging to the same trademark were considered. Regarding to the prevalence of CoNS carrying mecA gene, 81.5% of the isolated strains were mecA⁺, and 76.2% of these were phenotypically resistant to oxacillin. Three isolates carried the enterotoxin A gene (sea), 29.5% produced biofilm in a laboratory test, and α‐ or ß‐hemolysis were observed for 3% and 5.2%, respectively. This study highlights the extent of the antimicrobial resistance phenomenon in neglected foodborne microorganisms and the potential public health risks that are related to the consumption of CoNS‐contaminated soft cheese.     

Combined effect of aqueous chlorine dioxide and modified atmosphere packaging on inhibiting Salmonella Typhimurium and Listeria monocytogenes in mungbean sprouts

This study was conducted to investigate the effect of chlorine dioxide (ClO2) combined with modified atmosphere packaging (MAP) on inhibiting total mesophilic microorganisms, Salmonella Typhimurium, and Listeria monocytogenes in mungbean sprouts during refrigerated storage. Mungbean sprouts were packaged using 4 different methods (air, vacuum, CO2 gas, and N2 gas) following treatment with water or 100 ppm ClO2 for 5 min and stored at 5 +/- 2 degrees C. The population of total mesophilic microorganisms in mungbean sprouts was about 8.4-log(10) CFU/g and this level was not significantly reduced by treatment with water or ClO2 (P > 0.05). However, when samples were packaged under vacuum, N2 gas, or CO2 gas following treatment with ClO2, the populations of total mesophilic microorganisms were significantly reduced during storage (P < 0.05). Levels of S. Typhimurium and L. monocytogenes in mungbean sprouts following inoculation were 4.6- and 5.6-log(10) CFU/g and treatment with water followed by different packaging conditions (air, vacuum, N2 gas, and CO2 gas) had no significant effect on population reduction (P > 0.05). However, treatment with ClO2 significantly reduced populations of S. Typhimurium and L. monocytogenes by 3.0- and 1.5-log CFU/g, respectively (P < 0.05), and these reduced cell levels were maintained or decreased in samples packaged under vacuum or in N2 or CO2 gas during storage. These results suggest that the combination of ClO2 treatment and MAP such as CO2 gas packaging may be useful for inhibiting microbial contamination and maintaining quality in mungbean sprouts during storage.     

Antimicrobial activity of epsilon-polylysine against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in various food extracts

ABSTRACT:  This study compared the antimicrobial effects of ɛ-polylysine (ɛ-PL) against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in 6 food extracts and in broth. The food extracts (10% (w/w) in distilled water) evaluated were fat-free and whole fat milk, beef, bologna, rice, and vegetables (50:50 ratio of broccoli and cauliflower). ɛ-PL was tested at 0.005% and 0.02% (w/v) against E. coli O157:H7 and L. monocytogenes , and 0.02% and 0.04% (w/v) against S. Typhimurium . The substrates were inoculated (5 log CFU/mL) and periodically analyzed for surviving populations during storage at 12 °C for 6 d. In general, all 3 pathogens reached 7 to 9 log CFU/mL within 2 d in control substrates (no ɛ-PL). Immediate bactericidal effects ( P < 0.05) following exposure to ɛ-PL were obtained in the rice (all pathogens) and vegetable ( E. coli O157:H7 and S. Typhimurium ) extracts. During storage, antimicrobial effects of ɛ-PL were more pronounced in the food extracts than in the broth medium. The greatest antimicrobial activity for all 3 pathogens was obtained in the rice and vegetable extracts, where counts were reduced ( P < 0.05) to below the detection limit (0.0 log CFU/mL) by one or both ɛ-PL concentrations tested. In the other food extracts (fat-free milk, whole fat milk, beef, and bologna), both ɛ-PL concentrations tested generally resulted in lower ( P < 0.05) pathogen levels at the end of storage compared to initial counts, with better bactericidal effects exerted by the higher of the 2 ɛ-PL concentrations. Additional research is needed to explore the potential antimicrobial effects of ɛ-PL in real food systems.     

2015—2017年河南省食源性疾病致泻大肠埃希菌监测情况分析

目的 了解河南省食源性疾病致泻性大肠埃希菌(DEC)的致病型和分布情况,为食源性疾病的防控提供参考数据。方法 对哨点医院食源性疾病患者的粪便标本进行DEC检测,确定致病型和毒力基因。结果 4 137份粪便标本有215份DEC阳性,阳性检出率为5.2%,其中有4份标本是不同型别的DEC混合感染。共分离DEC菌株219株,其中肠聚集性大肠埃希菌(EAEC)156株,产肠毒素大肠埃希菌(ETEC)28株,肠致病性大肠埃希菌(EPEC)28株,肠出血性大肠埃希菌(EHEC)2株,肠侵袭性大肠埃希菌(EIEC)5株。215例阳性病例中,5岁以下儿童有95例,占比为44.2%。DEC病例在6月和10月有一个发病的高峰,在其他月份均有检出。可疑暴露食品中,由肉与肉制品、乳与乳制品引发的病例分别为34和31例,占比分别为17.3%(34/196)和15.8%(31/196)。结论 河南省食源性疾病DEC基因型中,EAEC占比最高,感染以5岁以下儿童为主,全年均有检出,夏秋季多发,肉与肉制品、乳与乳制品引发病例较多。     

婴幼儿食品和配方奶粉中克罗诺杆菌污染调查及分子分型研究

目的了解温州市市售婴幼儿食品和配方奶粉中克罗诺杆菌污染情况及分子分型特征,分析不同菌株间亲缘相关性。方法参照GB 4789.40—2010《食品安全国家标准食品微生物学检验阪崎肠杆菌检验》方法在食品中分离鉴定克罗诺杆菌。采用脉冲场凝胶电泳(PFGE)和多位点序列分型(MLST)方法对克罗诺杆菌进行分型研究。结果 2013—2017年共采集737份婴幼儿食品和配方奶粉,克罗诺杆菌总检出率为6.1%(45/737)。其中婴幼儿谷类辅助食品检出率最高(23.4%,37/158)。45株克罗诺杆菌属于阪崎克罗诺杆菌(C.sakazakii)、丙二酸盐克罗诺杆菌(C.malonaticus)和莫金斯克罗诺杆菌(C.muytjensii)。其中阪崎克罗诺杆菌最多(73.3%,33/45),其次为丙二酸盐克罗诺杆菌(24.4%,11/45)。MLST共分为25个ST型,其中ST64、ST1、ST40、ST4和ST7为优势型别。45株克罗诺杆菌PFGE分型得到38个带型,未发现有明显的优势分型和聚集现象。PFGE型和MLST型结果分析表明,绝大数具有相同PFGE型的菌株也有相同的MLST型,而相同MLST型却不一定具有较高的亲缘关系。结论温州市市售婴幼儿食品和配方奶粉中克罗诺杆菌的污染状况较轻,其中婴幼儿谷类辅助食品检出率最高。食品来源的克罗诺杆菌图谱具有高多态性和离散性。     

2018年北京市通州区居民冰箱使用习惯及卫生状况调查

目的 了解北京市通州区居民冰箱储存食物、清洗频率等使用习惯及卫生状况。方法 选取北京市通州区3个社区60户居民, 调查冰箱使用年限、冰箱内部是否定期清洗、水果、鸡蛋和熟食的储存习惯等。对冰箱冷藏室隔板和底部进行涂抹采样, 检测项目为大肠菌群、单核细胞增生李斯特菌、小肠结肠炎耶尔森菌和金黄色葡萄球菌。结果 调查居民60台冰箱, 使用年限<10年的占76.7%, 定期清洗冰箱的占80.0%。有41.6%的居民在冰箱冷藏室存放熟食与其他食物混放, 20.0%的居民将水果不包装放入冰箱, 13.3%的居民将鸡蛋与其他食物混放。采集冰箱内部涂抹样品120件, 大肠菌群检出率为31.7%(38/120), 冷藏室底部大肠菌群检出率高于冷藏室隔板(2=5.546, P=0.019)。未检出单核细胞增生李斯特菌、小肠结肠炎耶尔森菌、金黄色葡萄球菌。结论 居民冰箱储存食物方式及冷藏室卫生状况存在食品安全隐患, 因此应加强宣教和指导, 预防和减少食源性疾病发生。     

Effect of enterocin AS-48 in combination with biocides on planktonic and sessile Listeria monocytogenes

Enterocin AS-48 was tested on a cocktail of Listeria monocytogenes strains in planktonic and sessile states, singly or in combination with biocides benzalkonium chloride, cetrimide, hexadecylpyridinium chloride, didecyldimethylammonium bromide, triclosan, poly-(hexamethylen guanidinium) hydrochloride, chlorhexidine, hexachlorophene, and the commercial sanitizers P3 oxonia and P3 topax 66. Combinations of sub-inhibitory bacteriocin concentrations and biocide concentrations 4 to 10-fold lower than their minimum inhibitory concentrations (MIC) completely inhibited growth of the planktonic listeriae. Inactivation of Listeria in biofilms formed on polystyrene microtiter plates required concentrations of enterocin AS-48 greater than 50 μg/ml, and biocide concentrations ten to 100-fold higher. In combination with enterocin AS-48 (25 or 50 μg/ml), microbial inactivation increased remarkably for all biocides except P3 oxonia and P3 topax 66 solutions. Polystyrene microtiter plates conditioned with enterocin solutions (0.5-25 μg/ml) decreased the adherence and biofilm formation of the L. monocytogenes cell cocktail, avoiding biofilm formation for at least 24 h at a bacteriocin concentration of 25 μg/ml.