Genotypic characterization of Enterobacter sakazakii isolates by PFGE, BOX-PCR and sequencing of the fliC gene

Aims:  Enterobacter sakazakii is an emerging food-borne pathogen that can cause rare but severe forms of neonatal meningitis, bacteraemia and necrotizing enterocolitis. A rapid typing method at the strain level is needed to determine the monoclonality or polyclonality of the isolates during outbreaks.
Methods and Results:  The BOX-PCR fingerprinting technique, which targets the repetitive BOX sequences, and sequencing of the flagellin gene, fliC , were evaluated against a panel of 27 Ent. sakazakii strains from clinical and environmental sources. The typeability and discriminatory power of the techniques were compared with those of pulsed-field gel electrophoresis (PFGE), the reference genotyping method. BOX-PCR results yielded 92% agreement with PFGE results, whereas fliC gene sequencing was poorly discriminative.
Conclusions:  In our study, BOX-PCR and PFGE were similarly discriminatory to type Ent. sakazakii strains. The weak variability of the Ent. sakazakii fliC gene was related to the absence of the variable central domain present in most fliC genes of Enterobacteriaceae.
Significance and Impact of the Study:  The BOX-PCR typing provides an accurate discrimination and a rapid answer to identify clonal isolates of Ent. sakazakii .     

Resistance of Enterobacter sakazakii (Cronobacter spp.) to environmental stresses

Aim:  To gain a better understanding of the survival and persistence of Enterobacter sakazakii in severe environments.
Methods and Results:  We evaluated the resistance of Ent. sakazakii to various environmental stresses, including heating, drying, water activity ( a _w), and pH. The resistance of Ent. sakazakii to heat varies widely among strains. Most tested strains of Ent. sakazakii exhibited unusual resistance to dry stress, which depends on drying media. Growth of most strains occurred within 24 h at 37°C when the initial a _w of the medium was adjusted to 0·94 with sucrose or sodium chloride. The minimum pH for growth within 24 h at 37°C was 3·9 or 4·1 for most strains tested. Additionally, there did not appear to be any relationship between resistance to stresses and biofilm-forming ability in Ent. sakazakii planktonic cells.
Conclusions:  These results indicate that Ent. sakazakii is much more resistant than other Enterobacteriaceae to environmental stresses. Moreover, it is likely that Ent. sakazakii has cross-resistance to dry and thermal stresses.
Significance and Impact of the Study:  The findings of this study will contribute to an improved understanding of the survival and behaviour of Ent. sakazakii , which will lead to improved strategies for preventing outbreaks of Ent. sakazakii infection.     

Surfactin reduces the adhesion of food-borne pathogenic bacteria to solid surfaces

Aims:  To investigate the effect of the biosurfactants surfactin and rhamnolipids on the adhesion of the food pathogens Listeria monocytogenes , Enterobacter sakazakii and Salmonella Enteritidis to stainless steel and polypropylene surfaces.
Methods and Results:  Quantification of bacterial adhesion was performed using the crystal violet staining technique. Preconditioning of surfaces with surfactin caused a reduction on the number of adhered cells of Ent. sakazakii and L. monocytogenes on stainless steel. The most significant result was obtained with L. monocytogenes where number of adhered cells was reduced by 10² CFU cm⁻². On polypropylene, surfactin showed a significant decrease on the adhesion of all strains. The adsorption of surfactin on polystyrene also reduces the adhesion of L. monocytogenes and Salm. Enteritidis growing cells. For short contact periods using nongrowing cells or longer contact periods with growing cells, surfactin was able to delay bacterial adhesion.
Conclusions:  The prior adsorption of surfactin to solid surfaces contributes on reducing colonization of the pathogenic bacteria.
Significance and Impact of the Study:  This is the first work investigating the effect of surfactin on the adhesion of the food pathogens L. monocytogenes , Ent. sakazakii and Salm. Enteritidis to polypropylene and stainless steel surfaces.     

Desiccation and heat tolerance of Enterobacter sakazakii

AIMS: Enterobacter sakazakii is an opportunistic pathogen which has been isolated at low levels from powdered infant formulas. This study was performed to demonstrate that Ent. sakazakii is not particularly thermotolerant, but can adapt to osmotic and dry stress. METHODS AND RESULTS: We determined the heat, osmotic and dry stress resistance of Ent. sakazakii. The D-value at 58 degrees C ranged from 0.39 to 0.60 min, which is comparable with that of other Enterobacteriaceae, but much lower than reported previously (Nazarowec-White and Farber 1997, Letters in Applied Microbiology 24: 9-13). However, stationary phase Ent. sakazakii cells were found to be more resistant to osmotic and dry stress than Escherichia coli, Salmonella and other strains of Enterobacteriaceae tested. Further analysis indicated that the dry resistance is most likely linked to accumulation of trehalose in the cells. CONCLUSIONS: The high tolerance to desiccation provides a competitive advantage for Ent. sakazakii in dry environments, as found in milk powder factories, and thereby increases the risk of postpasteurization contamination of the finished product. SIGNIFICANCE AND IMPACT OF THE STUDY: Understanding of the physiology and survival strategies of Ent. sakazakii is an important step in the efforts to eliminate this bacterium from the critical food production environments.     

Heat resistance of Cronobacter species (Enterobacter sakazakii) in milk and special feeding formula

Aim:  To determine D - and z -values of Cronobacter species ( Enterobacter sakazakii ) in different reconstituted milk and special feeding formula and the effect of reconstitution of powdered milk and special feeding formula with hot water on the survival of the micro-organism.
Methods and Results:  Five Cronobacter species (four C. sakazakii isolates and C. muytjensii ) were heated in reconstituted milk or feeding formula pre-equilibrated at 52–58°C for various times or mixed with powdered milk or feeding formula prior to reconstitution with water at 60–100°C. The D -values of Cronobacter at 52–58°C were significantly higher in whole milk (22·10–0·68 min) than in low fat (15·87–0·62 min) or skim milk (15·30–0·51 min) and significantly higher in lactose-free formula (19·57–0·66 min) than in soy protein formula (17·22–0·63 min). The z -values of Cronobacter in reconstituted milk or feeding formula ranged from 4·01°C to 4·39°C. Water heated to ≥70°C and added to powdered milk and formula resulted in a > 4 log₁₀ reduction of Cronobacter .
Conclusions:  The heat resistance of Cronobacter should not allow the survival of the pathogen during normal pasteurization treatment. The use of hot water (≥70°C) during reconstitution appears to be an effective means to reduce the risk of Cronobacter in these products.
Significance and Impact of the Study:  This study supports existing data available to regulatory agencies and milk producers that recommended heat treatments are sufficient to substantially reduce risk from Cronobacter which may be present in these products.     

Effect of environmental stresses on the sensitivity of Enterobacter sakazakii in powdered infant milk formula to gamma radiation

Aim:  To evaluate the effect of starvation, heat, cold, acid, alkaline, chlorine and ethanol stresses on the resistance of Enterobacter sakazakii in powdered infant milk formula (PIMF) towards gamma radiation.
Methods and Results:  Stressed cells of E. sakazakii ATCC 51329 and four other food isolate strains were mixed individually with PIMF, kept overnight at room temperature, and then exposed to gamma radiation up to 7·5 kGy. The D ₁₀-values were determined using linear regression and for the stressed E. sakazakii strains these values ranged from 0·82 to 1·95 kGy.
Conclusions:  Environmental stresses did not significantly change the sensitivity of most E. sakazakii strains to ionizing radiation.
Significance and Impact of the Study:  Data obtained established that most forms of environmental stress are unlikely to significantly enhance the resistance of E. sakazakii strains to lethal, low dose irradiation treatment.     

Prevalence of Cronobacter species (Enterobacter sakazakii) in follow-on infant formulae and infant drinks

Aims:  To determine the prevalence of Cronobacter spp. ( Enterobacter sakazakii ) in follow-on formula powders commercially available in European countries.
Methods and Results:  A total of 470 samples comprising 31 different products from 18 brand names belonging to seven companies were tested for the presence of Cronobacter species. No milk- or soy-based infant formula powders were found to contain Cronobacter species . However, two cereal-based infant drinks were positive for Cronobacter sakazakii . A review of the published cases spanning the past 48 years did not reveal any fatalities attributable to Cronobacter spp. in children over 3 months.
Conclusions:  The low incidence of Cronobacter in infant powdered drinks, the lack of fatal Cronobacter infections in infants greater than 3 months and the low incidence of Cronobacter -related reported illness in this age group indicated that ingestion of these products presents a low risk for the intended consumers.
Significance and Impact of the Study:  The risk posed to neonates from the consumption of infant formula contaminated with Cronobacter is clear. Risks associated with powdered follow-on formulae intended for consumption by older infants is now under consideration by the World Health Organization. Our data contributes to the body of knowledge available for the assessment of the risk to consumers from these food products.     

Survival and growth of Cronobacter species (Enterobacter sakazakii) in wheat-based infant follow-on formulas

Aims:  To determine the survival and growth characteristics of Cronobacter species ( Enterobacter sakazakii ) in infant wheat-based formulas reconstituted with water, milk, grape juice or apple juice during storage.
Methods and Results:  Infant wheat-based formulas were reconstituted with water, ultra high temperature milk, pasteurized grape or apple juices. The reconstituted formulas were inoculated with Cronobacter sakazakii and Cronobacter muytjensii and stored at 4, 25 or 37°C for up to 24 h. At 25 and 37°C, Cronobacter grew more (>5 log₁₀) in formulas reconstituted with water or milk than those prepared with grape or apple juices ( c. 2–3 log₁₀). The organism persisted, but did not grow in any formulas stored at 4°C. Formulas reconstituted with water and milk decreased from pH 6·0 to 4·8–5·0 after 24 h, whereas the pH of the formulas reconstituted with fruit juices remained at their initial pH values, c. pH 4·8–5·0.
Conclusions:  Cronobacter sakazakii and C. muytjensii can grow in reconstituted wheat-based formulas. If not immediately consumed, these formulas should be stored at refrigeration temperatures to reduce the risk of infant infection.
Significance and Impact of the Study:  The results of this study will be of use to regulatory agencies and infant formula producers to recommend storage conditions that reduce the growth of Cronobacter in infant wheat-based formulas.     

Tracing of Enterobacter sakazakii isolates in infant milk formula processing by BOX-PCR genotyping

Aims:  Enterobacter sakazakii is an emerging food-borne pathogen that can cause rare but severe neonatal meningitis, bacteraemia and necrotizing enterocolitis. Contaminated powder infant formulae (PIF) have been identified as one of various infection routes. In this study, E. sakazakii was monitored in the processing environment of a PIF factory to identify possible dissemination routes.
Methods and Results:  The BOX-polymerase chain reaction (PCR), a fingerprinting technique which targets the repetitive BOX sequences, was used in routine to identify points of contamination and investigate clonal persistence. Two hundred E. sakazakii isolates were collected and typed. Most (70%) showed the same fingerprint that revealed the persistence of resident E. sakazakii strains in the processing environment. This method allowed to detect contamination of some PIF by dry-blending ingredients.
Conclusions:  Environment was the major cause for contamination of PIF and facilities. Some raw materials delivered as powder were also implicated.
Significance and Impact of the Study:  Routine BOX-PCR genotyping was very useful to trace and investigate in real-time dissemination of micro-organisms in the PIF plant and to implement a series of additional control measures to reduce the risk of final product contamination by E. sakazakii .     

Quantitative isolation efficiency of O26, O103, O111, O145 and O157 STEC serotypes from artificially contaminated food and cattle faeces samples using a new isolation protocol

Aims:  A range of new differential and confirmation plating media for some non-O157 Shiga toxin producing Escherichia coli (STEC) serotypes (O26, O103, O111, O145) and both sorbitol-positive and -negative O157 were evaluated using artificially contaminated samples.
Methods and Results:  Dairy products (raw milk, cheese made from pasteurized milk and raw milk), meat (ground beef, fermented meat) and cattle faeces were artificially contaminated using clinical STEC strains. Isolation efficiency was 100%, 82·3%, 88·5%, 65·9%, 64·3% and 15·8%, respectively, for an inoculum size of ≤100 CFU 25 g⁻¹. The consecutive use of differential and confirmation media limited the incidence of false positive isolates from 0% for raw milk samples, cheese made from pasteurized milk and for fermented meat to 2·1% for cheese made from raw milk, and to 8·9% for ground beef.
Conclusions:  Data presented in this paper indicated that the efficiency of the applied isolation method was dependent on sample-to-sample variation but not on the inoculum size.
Significance and Impact of Study:  Data in this paper indicated that isolation of low levels of non-O157 and sorbitol-positive O157 STEC from food samples is possible.     

Isolation of Enterobacter cowanii from Eucalyptus showing symptoms of bacterial blight and dieback in Uruguay

Aims:  This study was performed to identify bacterial strains isolated simultaneously with Pantoea species from Eucalyptus trees showing symptoms of bacterial blight and dieback in Uruguay.
Methods and Results:  Several molecular techniques including 16S rRNA and rpoB gene sequencing and DNA–DNA hybridization were used to characterize the Gram-negative, facultatively anaerobic, slime-producing bacterial strains isolated along with Pantoea species from Eucalyptus . Hypersensitivity reactions (HR) and pathogenicity tests were performed on tobacco and Eucalyptus seedlings, respectively. The isolates clustered closely with the type strain of Enterobacter cowanii in both phylogenetic trees constructed. The DNA–DNA similarity between the isolates and the type strain of Ent. cowanii ranged from 88% to 92%. A positive HR was observed on the tobacco seedlings, but no disease symptoms were visible on the inoculated Eucalyptus seedlings.
Conclusions:  Enterobacter cowanii was isolated from trees with symptoms of bacterial blight although strains of this bacterial species do not appear to be the causal agent of the disease.
Significance and Impact of the Study:  This study provides the first report of Ent. cowanii isolated from Eucalyptus . Its presence in Eucalyptus tissue suggests that it is an endophyte in trees showing symptoms of blight.     

Analysis of major band of Enterobacter sakazakii by ERIC-PCR and development of a species-specific PCR for detection of Ent. sakazakii in dry food samples

ERIC (Enterobacterial Repetitive Intergenic Consensus)-PCR was employed to generate stable and reproductive ERIC-PCR fingerprints of Ent. sakazakii ATCC51329. Moreover, this study also cloned and sequenced a major band of Ent. sakazakii (ATCC51329) ERIC-PCR fingerprints. The major band was amplified with primer ERIC2 and sequences extending primer ERIC 2 showed poor similarity with ERIC elements. A comparison of the nucleotide acid with other sequences available in the GenBank revealed 90% of identity with Ent. sakazakii ATCC BAA-894, and 73%-74% of identity with oligopeptiase gene or protease gene of some species from the Enterobacteriaceae family. Two primers were synthesized to develop and optimize an Enterobacter sakazakii-specific PCR based on regions of major band unique to Ent. sakazakii. The expected fragment was amplified from all of Ent. sakazkaii but not from the negative controls. As few as 10(2) CFU/ml of Ent. sakazakii of PCR were directly detected in the infant formulas. This was the case even in the presence of other bacteria. A comparison of traditional methods and new developed PCR in commercial foods suggested that without using API20-E test, the DFI chromogenic medium and FDA method showed 46.15% and 50% false positive respectively. Moreover, one false negative was observed with FDA method. In contrast, PCR was highly sensitive and specific to Ent. sakazakii. A high heterogeneity between Ent. sakazakii and the other microorganisms was found on expected fragment sequence. In addition, Ent. sakazakii ATCC51329 formed a separate branch with >5% divergence from the type strain ATCC BAA-894 and major strains.     

Evaluation of amino acid-decarboxylative microbiota throughout the ripening of an Italian PDO cheese produced using different manufacturing practices

Aim:  To investigate the presence of biogenic amines (BAs) in Montasio cheese produced by using different cheese manufacturing practices.
Methods and Results:  Three batches of Montasio cheese were made in the following way: batch A using raw milk and natural milk culture, batch B with thermized milk and natural milk culture and batch C with thermized milk and natural milk culture added of a commercial starter culture. During 120 days of ripening analyses were performed for microbial counts and BA content; indeed, the potential to produce BAs was screened in lactic acid bacteria and Enterobacteriaceae isolates. At the end of ripening, the total BA contents of cheeses from batches A, B and C were 166·3, 207·3 and 29·8 mg kg⁻¹, respectively. Amino acid decarboxylase activity was widespread among isolates.
Conclusions:  The BA content of Montasio cheese from the three batches was below the threshold proposed as potentially toxic. The highest BA content was found in cheese produced using thermized milk and natural milk culture; therefore, the thermal treatment of milk was not enough by itself to reduce the counts of decarboxylase-positive bacteria in cheese. The use of selected starters guaranteed a low BA content in Montasio cheese.
Significance and Impact of the Study:  The study of the effects of some technological processes on the incidence of decarboxylative microbiota in 'protected denomination of origin' cheeses could provide useful information on the hygienic risk related to their production.     

Effects of dietary probiotic supplementations on prevention/treatment of yersiniosis disease

Aims:  To evaluate Enterobacter cloacae and Bacillus mojavensis , isolated from rainbow trout gut in the present study, as a probiotic to control yersiniosis disease.
Methods and Results:  A strain of Ent. cloacae and B. mojavensis , isolated from the digestive tract of rainbow trout had an antagonistic effect to Yersinia ruckeri , which causes yersiniosis. After feeding fish with 1 × 10⁸ cells g⁻¹ probiotic containing feed for 60 days, the fish survival rate increased to 99·2% following challenge with Y. ruckeri compared with controls that had 35% survival rate. Effects of Ent. cloacae and B. mojavensis on weight gains and stimulation of red blood cells, white blood cells, platelets and hemoglobin were also evaluated in separate groups of fish fed probiotic containing feed for 2 months. Probiotic significantly affected white blood cells, hemoglobin and weight gains of the experimental fish.
Conclusions:  Enterobacter cloacae and B. mojavensis , can be used to prevent and control yersiniosis disease.
Significance and Impact of the Study:  In conclusion, concomitant use of Ent. cloacae and B. mojavensis as a feed supplement is beneficial to rainbow trout. Use of these organisms can protect fish from yersiniosis and enhance digestibility and utilization of feed. Use of such probiotics may also limit the use of antibiotics and other chemicals in control and treatment of diseases, and thus contribute to the effort to reduce environmental contamination by residual antibiotics and chemicals .     

Involvement of Enterobacter cloacae in the mortality of the fish, Mugil cephalus

Aims:  To identify the causative agent of the mortality in the fish, Mugil cephalus , in Muttukadu lagoon.
Methods and Results:  An enteric bacterium from the kidneys of moribund fish M. cephalus , was isolated and identified as Enterobacter cloacae (MK). Mugil cephalus was experimentally infected by this isolate and was re-isolated from the kidneys of the moribund fish. Enterobacter cloacae isolates from the lagoon water (MW1, MW2 and reference strain ATCC 13047) and the reference strain were not able to induce similar pathogenesis. The putative factor imparting pathogenicity to the MK isolate was identified as a cationic molecule, which migrated towards the cathode on agarose gel electrophoresis.
Conclusions:  The Ent. cloacae (MK) isolate harbouring a cationic factor was the causative agent for the mortality of M. cephalus , found in Muttukadu lagoon.
Significance and Impact of the Study:  This study reveals that human enteric bacteria MK which is considered as nonpathogenic to fish, may become pathogenic to fish when it harbours this cationic factor. This cationic factor is found to be pathogenic to the fish M. cephalus leading to mortality. It was also found to be pathogenic to mice. Therefore, the shuttling of Ent. cloacae , harbouring cationic factor, between human and fish may be of human health importance.     

Thermal resistance of Enterobacter sakazakii in reconstituted dried-infant formula

Enterobacter sakazakii , designated a unique species in 1980, has been implicated in a rare but severe form of neonatal meningitis, with dried-infant formula being implicated as the mode of transmission. The high mortality rate (40–80%) and the lack of information about this organism led to a study of the heat resistance of Ent. sakazakii in reconstituted dried-infant formula. Ten Canadian Ent. sakazakii strains (5 clinical and 5 food isolates) were used to determine the heat resistance of this organism at 52, 54, 56, 58 and 60°C in reconstituted dried-infant formula. D - values of 54·8, 23·7, 10·3, 4·2 and 2·5 min were obtained for each temperature, respectively. The overall calculated z -value was 5·82°C. In a comparison of the D -values of several members of the Enterobacteriaceae in dairy products, Ent. sakazakii appeared to be one of the most thermotolerant organisms. The importance of process control during manufacture and the use of aseptic procedures during the preparation, use and storage of dried-infant formula is discussed.     

Microbial population profiles of the microflora associated with pre- and postharvest tomatoes contaminated with Salmonella typhimurium or Salmonella montevideo

Aims:  To determine the microflora profiles of pre- and postharvest tomatoes contaminated with Salmonella montevideo or S. typhimurium DT104.
Methods and Results:  Salmonella montevideo or S. typhimurium was inoculated onto the flowers of tomato plants with the microflora of the subsequent fruit examined using a combination of Source Carbon Utilization and 16S rDNA-PCR profiling. From 16S rDNA profiles it was evident that tomatoes derived from Salmonella inoculated plants harboured a different microbial population compared to nontreated controls. The same result was observed for tomatoes inoculated at postharvest and subsequently stored for 14 days at 15°C. From sequencing analysis it was found that tomatoes derived from Salmonella inoculated plants but testing negative for the enteric pathogen, frequently harboured Enterobacter and Bacillus spp. In contrast, both bacterial types were not found associated with tomatoes testing positive for Salmonella.
Conclusions:  Salmonella introduced onto tomatoes at pre- or postharvest alters the composition of the microbial community. The presence of Enterobacter and Bacillus spp negatively affects the persistence of Salmonella on preharvest tomatoes.
Significance and Impact of the Study:  Salmonella appears to modify rather than become integrated into the microbial communities associated with tomatoes. Yet, the presence of antagonistic bacteria appears to reduce the persistence of the enteric pathogen.     

The growth profile, thermotolerance and biofilm formation of Enterobacter sakazakii grown in infant formula milk

AIMS: To study the growth, thermotolerance and biofilm formation of the emergent pathogen Enterobacter sakazakii in infant formula milk (IFM). METHODS AND RESULTS: The temperature range, death kinetics and biofilm formation of E. sakazakii were determined using impedance microbiology and conventional methods. In IFM the organism grew as low as 6 degrees C and optimally at 37-43 degrees C. In faecal coliform tests, 23% of strains (n = 70) produced gas from lauryl sulphate broth (LSB) at 44 degrees C after 48 h incubation. Three strains failed to grow in LSB at any of the temperatures. The D-value of cells suspended in IFM was determined between 54 and 62 degrees C. The resultant z-value was 5.7 degrees C. The organism was able to adhere and grow on latex, polycarbonate, silicon and to a lesser extent stainless steel. CONCLUSIONS: Enterobacter sakazakii was able to grow at refrigeration temperatures and on infant-feeding equipment. The thermotolerance of the organism was similar to other Enterobacteriaceae and should be killed during standard pasteurization treatment. SIGNIFICANCE AND IMPACT OF THE STUDY: Enterobacter sakazakii has been associated with infant meningitis through consumption of contaminated IFM. Enterobacter sakazakii is able to grow in IFM during storage at refrigeration temperatures and attach to infant-feeding equipment, which may become reservoirs of infection.     

A survey of the enterococci isolated from an artisanal Italian goat's cheese (semicotto caprino)

Enterococci were isolated from semicotto caprino cheese, a traditional cheese produced in Southern Italy: they were a significant part of the microbial population of this cheese, confirming the importance of the presence of these micro-organisms during cheese-making and ripening. They were also identified and studied for their phenotypic and genotypic characteristics: Enterococcus faecalis and Ent. faecium were the most frequently isolated species, followed by Ent. durans, Ent. hirae and Ent. gallinarum. None of the isolates showed lipolytic activity, whereas they were characterized by a relevant proteolytic activity as well as an antagonistic activity towards Listeria innocua. One strain of Ent. gallinarum showed a low-level resistance to vancomycin, while six out of the 79 Ent. faecalis strains possessed beta-haemolysis reaction. The highest acidifying potential in skim milk was obtained by Ent. faecalis isolates. Thirty enterococcal strains representative of the different species at different ripening times were analysed by means of RAPD-PCR, and revealed species-specific profiles for all the considered species.     

阪崎肠杆菌显色培养基的应用研究

阪崎肠杆菌(Enterobacter sakazakii)是新近引起广泛关注的一种危险的条件致病菌, 主要存在于婴幼儿奶粉、婴幼儿补充食品中。由于目前日常使用的传统检验方法存在检测周期长等方面的不足之处, 本实验室研究设计出一种新的显色培养基(HKMCES), 通过与OXOID公司的同类产品(OXCES)比较, 分别应用于质控菌株、污染样品和实际样品的测试, 对这2种显色培养基的灵敏度、特异性、检测效果以及前增菌方法进行了初步评价。结果表明, 合适的增菌方法更有利于样品中阪崎肠杆菌的检出, 本实验室研制的显色培养基和OXOID公司的显色培养基均具有较好的选择性和特异性, 检测效果相当。这种新的显色培养基能使检测周期缩短, 具有较好的应用价值。