婴儿配方粉中克雷伯氏菌的检出及污染情况

对婴儿配方粉中肠杆菌科细菌进行筛查,检出婴儿配方粉中污染了肺炎克雷伯氏菌和产酸克雷伯氏菌,检测样本241份,污染几率分别为5.0%和2.5%。所采用的检验方法为VRBGA结合MIAC进行分离,采用API20E和VITEC2进行生化鉴定。     

产酸克雷伯式菌(Klebsiella Oxytoca XCH-1)的分离鉴定及其特性研究

从青岛海藻化工厂海带浸泡液中分离筛选出1株菌,该菌在生长过程中产生大量的粘性胞外多糖。对该菌的形态特征、生长和生理生化特性进行了研究,经鉴定该菌为产酸克雷伯式菌(Klebsiellaoxytoca),命名为KlebsiellaoxytocaXCH-1。     

产酸克雷伯氏菌胞外多糖单糖组成的气相色谱分析

从青岛海藻化工厂海带浸泡液中分离得到产酸克雷伯氏菌(KlebsiellaoxytocaXCH-1)。在有氧条件下,该菌在生长过程中产生大量的胞外多糖,并且粘度很大。目前国内外尚未有关于该菌胞外多糖理化性质的研究报道。实验用KlebsiellaoxytocaXCH-1胞外多糖为化学均一物质。用气相色谱分析法分析KlebsiellaoxytocaXCH-1胞外多糖单糖组分,结果表明其主要由D-葡萄糖、D-半乳糖和L-鼠李糖组成。     

产酸克雷伯氏菌降解氯氰菊酯农药发酵条件的优化

采用Plackett-Burman法考察了环境因素对产酸克雷伯氏菌降解氯氰菊酯的影响,并筛选出影响其降解效果的主要因素,即pH、温度和接种量。在此基础上,利用Box-Behnken实验设计和响应面分析法对其降解条件进行了优化。验证结果显示,当培养基中氯氰菊酯含量为200mg/L、pH为6.8、接种量(种子液OD6001.000)为5.8%(v/v)、250mL锥形瓶装液量为30mL、33℃培养120h时,产酸克雷伯氏菌对氯氰菊酯的降解率达到84.67%。     

木糖发酵高产2,3-丁二醇菌株的选育

以肺炎克雷伯氏菌(Klebsiella pneumoniae)CICC10011为出发菌株,进行紫外诱变选育。通过2,3-丁二醇抗性和产酸能力对诱变菌株进行初筛,发酵后23,-丁二醇产量检测进行复筛,获得6株高产2,3-丁二醇的肺炎克雷伯氏菌,其中产量最高的一株诱变菌U3-17,与出发菌株相比,产量提高了21.5%。在摇瓶批式补料发酵中,诱变株U3-17的23,-丁二醇产量达49.3 g/L。     

从变质肉肠中检出肺炎克雷伯氏菌的报告

从变质肉肠中检出肺炎克雷伯氏菌的报告戴昌芳，黄吉诚，宋曼丹广东省食品卫生监督检验所（５１０３００）对广东省番禺市某肉联食品厂生产的两份变质肉肠样品检验分析，检出肺炎克雷伯氏菌，证明变质原因由该细菌引起。１材料与方法１１材料变质肉肠样品采自广东番禺市某...     

广东省首起米粉米酵菌酸中毒病原菌鉴定研究

目的对广东省首次因食用河粉引起米酵菌酸中毒的病原菌进行检测、鉴定和分析。方法病原菌的分离和鉴定参照GB/T 4789.29—2003《食品卫生微生物学检验椰毒假单胞菌酵米面亚种检验》,同时采用16S rDNA序列测序进行分子鉴定。结果 31份食物中毒相关食品样品中有10份检出伯克霍尔德菌(28株),包括唐菖蒲伯克霍尔德菌(15株)、洋葱伯克霍尔德菌(3株)、越南伯克霍尔德菌(3株)等,经16S rDNA的序列测定、产毒培养、米酵菌酸测定、毒力试验等分析,在3份样品中检出14株可产生米酵菌酸的唐菖蒲伯克霍尔德菌。结论采用生化并结合16S rDNA序列测定鉴定唐菖蒲伯克霍尔德菌,结合产毒试验可确定为引起米酵菌酸食物中毒的是唐菖蒲伯克霍尔德椰毒致病种。     

基质辅助激光解析电离飞行时间质谱法鉴定乳粉中致病菌

目的 采用基质辅助激光解析电离飞行时间质谱法鉴定乳粉中的几种食源性致病微生物, 评价此技术在乳粉安全评价中的应用前景。方法 以乳粉中常见几种食源性致病菌(阪崎肠杆菌、肺炎克雷伯氏菌、产酸克雷伯氏菌)为目标菌, 同时分离未知菌, 通过基质辅助激光解吸附电离飞行时间质谱进行鉴定。结果 共从80个样品中分离到3种细菌, 分别为阪崎肠杆菌、肺炎克雷伯氏菌, 阴沟肠杆菌。结论 基质辅助激光解吸附电离飞行时间质谱能快速对未知细菌进行鉴定, 本次实验从乳粉上分离到的细菌, 多数为条件致病菌, 存在一定的食用风险。     

益生菌Lactobacillus helveticus 130B4在牛乳中的生长特性及其促长因子研究

将具有ACE抑制活性的乳酸菌Laaobacillus helveficus 130B4用于发酵乳制品中,研究其在还原脱脂乳中的生长特性,并探讨通过添加生长促进物质对Laaobadllus helveticus 130B4生长特性以及对ACE抑制活性的影响.结果表明,Lb.helveticus 13084菌株在还原脱脂乳培养基中生长较缓慢,产酸能力较弱,37℃培养36 h后的pH值为4.31,酸度达0.8%,活菌数为8.93 g-1;72 h后的pH值为3.45,酸度可以达到1.85%,活菌数达9.1 g-1;酵母浸膏、大豆肽、核酸关联物质对该菌株的产酸能力有一定的促进作用.     

己酸菌W_1的分离特性及产酸条件的研究

已酸菌W_1是从宜宾五粮液酒厂的500年老窖泥中分离得到的高产已酸的菌株,经分类鉴定,该菌与克氏梭菌(Clostridium kluyverii)的特性很不相同,因此,无法划入克氏梭菌种内,暂定(Clostridium sp.W_1)。 经对W_1菌产酸条件的研究,该菌属于耐气性厌氧菌,用简单的液体合成培养基深层培养,就可满足生长。该菌生长的适宜温度为34℃,适宜的产酸的pH范围为6.5～7.5,乙醇和乙酸钠是该菌生长和产已酸的主要基质。     

Virulence properties of extended spectrum β-lactamase-producing Klebsiella species in meat samples

The present study was carried out to identify virulence properties (siderophores, serum resistance, and hemolysin) and antibiotic resistance in extended spectrum β-lactamase (ESBL)-producing Klebsiella isolates from 60 calf and chicken meat samples purchased from various supermarkets in Ankara, Turkey. Of the 45 Klebsiella isolates, 24 (53%) were identified as K. oxytoca and 21 (47%) were identified as K. pneumoniae. A high proportion of Klebsiella isolates had virulence factors such as hemolytic activity (67%), siderophore production (44%), and serum resistance (38%). The double-disk synergy test was used to determine ESBL production. ESBL production was detected in 13 (29%) of the 45 Klebsiella isolates. Resistance to 14 antimicrobials was tested in all Klebsiella isolates by the disk diffusion method. All isolates were resistant to two or more antimicrobial agents. All ESBL-producing Klebsiella isolates were highly resistant to cephalosporins and monobactams. Our findings indicate that meat and its products represent potential hazardous sources of multidrug-resistant and virulent Klebsiella species.     

SIDEROPHORE PRODUCTION, SERUM RESISTANCE, HEMOLYTIC ACTIVITY AND EXTENDED-SPECTRUM β-LACTAMASE-PRODUCING KLEBSIELLA SPECIES ISOLATED FROM MILK AND MILK PRODUCTS

This study aimed at the isolation and identification of Klebsiella spp. from dairy product to establish their public health significance by determining their virulence factors, antibiotic resistance and extended‐spectrum β‐lactamase (ESBL). Klebsiella pneumoniae, Klebsiella oxytoca and Klebsiella rhinoscleromatis were identified in 25 (58%), 11 (26%) and 7 (16%) isolates, respectively. A high prevalence of Klebsiella isolates had virulence factors such as siderophore production (63%), serum resistance (32.5%) and hemolytic activity (58%). ESBL‐producing Klebsiella spp. was detected in 35% of the isolates. Resistance to the antimicrobial agents tested was found to be much higher in the ESBL‐producing Klebsiella spp. than in non‐ESBL‐producing isolates. All ESBL‐producing Klebsiella spp. showed high‐level resistance to cephalosporins and monobactams. The majority of the serum resistant, siderophore, hemolysin and ESBL producers were K. pneumoniae.     

2009年海口市公共餐(饮)具大肠菌群污染状况及其菌群分类结果报告

目的 阐述海口市2009年大肠菌群各菌型在公共餐(饮)具中造成污染的状况。方法 对公共餐(饮)具大肠菌群污染状况进行统计分析,并对200株大肠菌群阳性菌进行鉴定分型。结果 2009年全市共检测公共餐(饮)具4091份,合格3498份,总合格率为85.5%。200株大肠菌群中,共检出肺炎克雷伯氏菌107株,占53.5%;阴沟肠杆菌46株,占23.0%;弗劳地氏柠檬酸杆菌29株,占14.5%;大肠埃希氏菌18株,占9.0%。结论 肺炎克雷伯氏菌是2009年海口市公共餐(饮)具大肠菌群污染的主要型别。     

Monitoring and identification of bacteria associated with safety concerns in the manufacture of São Jorge, a Portuguese traditional cheese from raw cow's milk

The aim of this study was to assess the hygienic quality of raw milk used in the manufacture of S?o Jorge, a Protected Denomination of Origin Portuguese semihard cheese, as well as to ascertain the sanitary conditions prevailing during its processing. Viable counts of Enterobacteriaceae and Micrococcaceae were accordingly obtained, pertaining to 21 independent batches (including samples of raw milk, curd, and cheeses after 1, 3, and 4 months of ripening), from 7 dairy farms. Standard plate counts (log CFU per milliliter or per gram) ranged from 6.1 to 8.6 in raw milk, whereas they ranged from 7.0 to 8.0 in 4-month-old cheeses. Viable counts of Enterobacteriaceae ranged between 5.9 and 7.0 in raw milk and between 0.0 and 1.3 in 4-month-old cheeses. Species identified within this family encompassed Klebsiella oxytoca, Klebsiella cloacae, Klebsiella pneumoniae, Enterobacter sakazakii, and Escherichia coli; Klebsiella ornithinolytica, Klebsiella terrigena, and Serratia odorifera were detected only in raw milk. No Salmonella whatsoever could be detected in any of the samples. Viable counts of Micrococcaceae ranged between 4.7 and 5.9 and between 1.3 and 3.3 in raw milk and 4-month-old cheeses, respectively. Species identified within this family encompassed Staphylococcus sciuri, Staphylococcus epidermidis, Staphylococcus saprophyticus (which was found mainly in ripened cheeses), and Staphylococcus aureus (which was not detected in 4-month-old cheeses). Accompanying physicochemical analyses included determination of moisture, salt, and pH. Statistical analyses revealed a negative correlation between salt content and viable numbers of Enterobacteriaceae in cheese, whereas in the case of Micrococcaceae, a more negative correlation was found between viable numbers and moisture content than between viable numbers and pH. The results of our study indicate, in general, poor milk handling conditions in all farms, given that the indicators total mesophile and Enterobacteriaceae counts were high, between 100- and 1,000-fold those enforced by international standards pertaining to the matrices in question. However, by the time of regular consumption (i.e., after 4 months of ripening), S?o Jorge cheeses exhibit low levels of contamination by Enterobacteriaceae and S. aureus, as well as absence of Salmonella.     

Production of biogenic amines by<Emphasis Type="Italic"> Morganella morganii</Emphasis>,<Emphasis Type="Italic"> Klebsiella pneumoniae</Emphasis> and<Emphasis Type="Italic"> Hafnia alvei</Emphasis> using a rapid HPLC method

The histidine decarboxylating activity and production of biogenic amines by Morganella morganii (NCIMB, 10466), Klebsiella pneumoniae (NCIMB, 673) and Hafnia alvei (NCIMB, 11999) were investigated using a rapid HPLC method. Derivatisation of the bacterial samples was carried out using benzoyl chloride. A gradient elution system was used for analysis with a mixture of acetonitrile and HPLC grade water. Bacterial strains not only produce histamine in histidine-enriched broth but also the other biogenic amines. The chromatographic results show that bacterial strains are also capable of producing spermine and spermidine in histidine-enriched broth. Bacterial ammonia production by all three strains was clearly detected since ammonia is generated during the degradation of histidine. The study demonstrates that the highest histamine production was obtained by Morganella morganii, followed by Klebsiella pneumoniae, and the lowest with the Hafnia alvei. Therefore, Morganella morganii and Klebsiella pneumoniae have strong histidine decarboxylase activity since they are prolific histamine-forming bacteria     

Microbiological characteristics and detection of capsular forms of bacteria of the intestinal group in confectionery produced at the candy-chocolate factories

Five types of confectionery and its semifinished products were investigated for contamination with Klebsiella, mesophilic aerobic and elective anaerobic, coliform bacteria, E. coli, etc. after a long-term storage. E. coli and St. aureus were not detected after inoculation on 1 g of the product; mold fungi were identified only in singular samples, their level did not exceed 20 CFU/g; the level of mesophilic aerobic and elective anaerobic bacteria varied from several hundreds to 3000-5500 CFU/g; coliform bacteria were identified in the amounts from 11 to 100 CFU/g. The identification of coliform bacteria has evidenced the presence of Enterobacter aerogenes and Kl. pneumoniae in the products investigated. Klebsiella were detected in 28-30% of the samples analyzed, their level did not exceed 100 CFU/g. The authors have proved the necessity of microbiological control of starting material, semifinished and finished confectionery products for the above bacteria.     

Isolation and characterization of multidrug-resistant Klebsiella spp. isolated from shrimp imported from Thailand

A study was undertaken to isolate and characterize tetracycline and nalidixic acid-resistant Klebsiella spp. in farm-raised, imported shrimp sold in the United States. Sixty-seven multiple antibiotic-resistant Klebsiella spp. strains were isolated from imported shrimp samples. Using morphological and biochemical methods, fifty-three strains were tentatively identified as Klebsiella pneumoniae and fourteen as K. oxytoca. Although all isolates were resistant to tetracycline, only 8 were resistant to nalidixic acid. These 8 isolates were further screened by PCR for quinolone resistance genes (qnrA, B, S, gyrA, B and parC). PCR protocols failed to amplify any qnr genes. The purified PCR amplicons of gyrA, gyrB and parC were sequenced and analyzed for point mutations that confer resistance to fluoroquinolone antibiotics. Analysis of the sequences of the gyrA amplicons from nalidixic acid-resistant Klebsiella spp. indicated two point mutations in gyrA at positions 83 (Ser→Phe) and 87 (Asp→Ala). Sequence analysis of the parC amplicons indicated an amino acid change at position 80 (Ser→Ile). No mutations were detected in gyrB. Template DNA from all isolates was screened for tetracycline resistance genes (tetA-E). Oligonucleotide primers specifically targeting a 305-bp region of tetB and a 477-bp region of tetD successfully amplified sequences from 91.0 and 44.0% of the isolates, respectively. None of the isolates contained tetA, tetC or tetE genes. Plasmids (2.0-16.0kb) were found in 23 of the 67 isolates. XbaI-PFGE identified 32 distinct macro restriction patterns (mrps) among the 61 multiple drug-resistant Klebsiella spp. that were typable. Our results indicate that imported shrimp is a reservoir for multidrug resistant Klebsiella spp. and potential health risks posed by such strains should not be underestimated.     

Occurrence of Listeria and Enterobacteriaceae in domestic refrigerators

Consumers' refrigeration practices have a significant impact on the safety and quality of foods. To determine the prevalence and the identity of microorganisms in domestic refrigerators, swab samples were taken from various locations in the refrigerators from 137 households in middle Tennessee. The swabs were inoculated into different media, and standard procedures were used to characterize the isolates. API 20E and API Listeria were used for identification of Enterobacteriaceae and Listeria spp., respectively. The Kirby-Bauer technique was used to test resistance of the isolates. Actual counts for aerobic and Enterobacteriaceae ranged from not detected to 8.53 and 8.39 log CFU per sample, respectively. Klebsiella pneumoniae (23.4%), Klebsiella oxytoca (6.8%), Klebsiella terrigena (4.0%), Enterobacter sakazakii (2.2%), and Yersinia enterocolitica (0.7%) were some of the bacteria of concern that were isolated from domestic refrigerators. Resistance to antibiotics was most common in erythromycin (39.9%), followed by ampicillin (33.8%), cefoxitin (12.8%), tetracycline (5%), streptomycin (4.0%), nalidixic acid (2.1%), kanamycin (1.4%), and colistin (0.7%). None of the isolates tested was resistant to ciprofloxacin or gentamycin. Listeria spp. were also detected in six refrigerators. These findings underline the need for greater consumer education regarding proper refrigerator cleaning and safe food handling practices.     

Characterization of the bovine innate immune response to intramammary infection with Klebsiella pneumoniae

Gram-negative bacteria are responsible for almost one-half of the clinical cases of mastitis that occur annually. Of those gram-negative bacteria that induce mastitis, Klebsiella pneumoniae remains one of the most prevalent. Detection of infectious pathogens and the induction of a proinflammatory response are critical components of host innate immunity. The objective of the current study was to characterize several elements of the bovine innate immune response to intramammary infection with Klebsiella pneumoniae. The inflammatory cytokine response and changes in the levels of soluble CD14 (sCD14) and lipopolysaccharide (LPS)-binding protein (LBP), 2 proteins that contribute to host recognition of gram-negative bacteria, were studied. The contralateral quarters of 7 late-lactating Holstein cows were challenged with either saline or K. pneumoniae, and milk and blood samples were collected. Initial increases in the chemoattractants C5a and IL-8, as well as TNF-alpha, were evident in infected quarters within 16 h of challenge and were temporally coincident with increases in milk somatic cells. Augmented levels of TNF-alpha and IL-8 were observed in infected quarters until >48 h postchallenge, respectively. Elevated levels of IL-12, IFN-gamma, and the antiinflammatory cytokine, IL-10, which were first detected between 12 and 20 h postinfection, persisted in infected quarters throughout the study (>96 h). Initial increases in milk LBP and sCD14 were detected 16 and 20 h, respectively, after challenge. Together, these data demonstrate that intramammary infection with K. pneumoniae elicits a host response characterized by the induction of proinflammatory cytokines and elevation of accessory molecules involved in LPS recognition.     

Enhancing the capacity of food consumption surveys of short duration to estimate long term consumer-only intakes by combination with a qualitative food frequency questionnaire

In principle, a proper risk assessment for a food chemical requires that the time-frame for food chemical intake estimates matches the time-frame for the toxicological assessments upon which the safety statements (ADI, PTW I, etc.) are based. For food additives, the toxicological assessments are based on exposure over a lifetime. While food consumption data cannot be collected over the lifetimes of individuals, the information should reflect habitual intakes as closely as possible. This study investigated the possibility of combining a 3-day food diary with a food frequency questionnaire to estimate mean consumer-only food intakes comparable to estimates based on a 14-day diary. The study population consisted of 948 teenagers and analysis was based on 32 clearly defined foods. For 47% of the foods, the difference was ≤ 1g/day. When expressed as portion sizes, 56% of the foods showed differences representing 14% of an average portion. When between-method differences (portions/day) were plotted against the mean of the methods, the mean between-method difference was 0.02 (± 0.06) portions/ day with limits of agreement of -0.10 to 0.14. This preliminary investigation suggests that the combined 3-day diary and FFQ method provides comparable estimates of mean consumer only intakes to a 14-day diary. Therefore, a qualitative FFQ may be a useful adjunct to a food consumption survey of short duration if estimates of longer term food intakes are required.