Impact of Dilution Ratios on Listeria monocytogenes Growth during University of Vermont Medium Enrichment of Deli Meats

2007 ◽  
Vol 70 (11) ◽  
pp. 2656-2660 ◽  
Author(s):  
LEI ZHANG ◽  
ZHINONG YAN ◽  
ELLIOT T. RYSER
Keyword(s):  
Detection Limit ◽  
Large Scale ◽  
Most Probable Number ◽  
Department Of Agriculture ◽  
Probable Number ◽  
Generation Times ◽  
Enrichment Protocol ◽  
Homogenization Methods ◽  
The Impact ◽  
University Of Vermont

In the U.S. Department of Agriculture (USDA) method for Listeria detection, a 25-g composite food sample is enriched in 225 ml of University of Vermont medium (UVM), giving a detection limit of 0.04 CFU/g. However, in a recent large-scale four-state deli meat survey for L. monocytogenes, 125-g samples enriched in 1,125 ml of UVM were requested to increase the detection limit to 0.008 CFU/g. To circumvent problems associated with large volumes of UVM, the impact on L. monocytogenes growth of lower dilution ratios used for enrichment and most-probable-number (MPN) detection was compared with the results obtained using the conventional 1:10 dilution. In this study, 125-g samples of cured turkey, uncured turkey, ham, and roast beef were inoculated with a six-strain L. monocytogenes cocktail to contain ∼1 × 103 CFU/g. This cocktail was then diluted 1:3, 1:5, or 1:10 in UVM, homogenized, enriched at 30°C, and periodically plated on modified Oxford agar to determine generation times during 24 h of incubation. The same enrichment protocol was also assessed in a three-tube MPN assay using 125-g samples inoculated with L. monocytogenes to contain ∼1 CFU/g. The effects of two homogenization methods, stomaching and pulsifying, on Listeria growth were compared using oven-roasted turkey breast diluted 1:3, 1:5, and 1:10 in UVM. Overall, the growth rates, generation times, and MPN values for each of the four selected deli meats were similar (P > 0.05) using UVM enrichment ratios of 1:3, 1:5, and 1:10, with no significant (P > 0.05) differences in L. monocytogenes growth rate or generation time between experiments using pulsifying and stomaching. These findings indicate that lower volumes of UVM can be used in the USDA procedure when examining deli meats without compromising Listeria recovery.

Quantification of Campylobacter on the Surface and in the Muscle of Chicken Legs at Retail

2006 ◽  
Vol 69 (4) ◽  
pp. 757-761 ◽  
Author(s):  
KATHRIN SCHERER ◽  
EDDA BARTELT ◽  
CHRISTINE SOMMERFELD ◽  
GOETZ HILDEBRANDT
Keyword(s):  
Detection Limit ◽  
Campylobacter Jejuni ◽  
Most Probable Number ◽  
Campylobacter Coli ◽  
Seasonal Influence ◽  
Probable Number ◽  
Internal Contamination ◽  
Chicken Legs ◽  
Two Peaks ◽  
Skin Samples

The objective of this study was to determine the prevalence and numbers of Campylobacter on the skin and in the muscle of chicken legs at retail to examine the external and internal contamination for an exposure assessment. Furthermore, the study assessed seasonal influence on Campylobacter contamination in chicken legs. Of the 140 examined skin samples, 66% were positive, and the internal contamination of 115 sampled chicken legs was 27%. The enumeration of Campylobacter on the surface of positive chicken legs revealed a median of 2.4 log CFU/g of skin, and the quantification of Campylobacter in the muscle gave results mainly under the detection limit of the most-probable-number method (<0.3 MPN Campylobacter per g). The external contamination was significantly higher than the internal. In both skin and muscle samples, Campylobacter jejuni had a much higher incidence than Campylobacter coli. However, with regard to the specification of Campylobacter on the surface of chicken legs, C. coli was isolated at higher colony counts than C. jejuni. During the 1-year study, two peaks of Campylobacter contamination occurred, one in the early springtime (February and March, 100 and 90%, respectively) and the second during the warmer months in the summer (July and August, both 90%). Furthermore, a positive correlation between prevalence and numbers of Campylobacter on chicken legs was observed.

scholarly journals The Impact of Water Intrusion on Pathogenic Vibrio Species to Inland Brackish Waters of China

2020 ◽  
Vol 17 (18) ◽  
pp. 6781
Author(s):  
Qingyao Wang ◽  
Songzhe Fu ◽  
Qian Yang ◽  
Jingwei Hao ◽  
Can Zhou ◽  
...  
Keyword(s):  
Seawater Intrusion ◽  
Water Area ◽  
Vibrio Species ◽  
Most Probable Number ◽  
Potential Health ◽  
Probable Number ◽  
Inland River ◽  
Pathogenic Vibrio ◽  
The Impact ◽  
Vibrio Spp

The estuary is the ecological niche of pathogenic Vibrio spp. as it provides abundant organic and inorganic nutrients from seawater and rivers. However, little is known about the ecology of these Vibrio species in the inland brackish water area. In this study, their co-occurrence and relationships to key environmental constraints (salinity and temperature) in the Hun-Tai River of China were examined using the most probable number polymerase chain reaction (MPN-PCR) approach. We hereby report 2-year continuous surveillance based on six water indices of the Hun-Tai River. The results showed that seawater intrusion maximally reached inland as far as 26.5 km for the Hun-Tai River. Pathogenic Vibrio spp. were detected in 21.9% of the water samples. In particular, V. cholerae, V. parahaemolyticus, and V. vulnificus were isolated in 10 (10.4%), 20 (20.8.5%), and 2 (2.08%) samples, respectively. All V. parahaemolyticus strains were tdh gene negative, 10% were positive for the trh gene. Multi-locus sequence typing (MLST) divided V. parahaemolyticus strains into 12 sequence types (STs) for the Hun-Tai River. Five STs were respectively present in various locations along the Hun-Tai River. The PCR assay for detecting six virulence genes and Vibrio seventh pandemic island I and II revealed three genotypes in 12 V. cholerae isolates. The results of our study showed that seawater intrusion and salinity have profound effects on the distribution of pathogenic Vibrio spp. in the inland river, suggesting a potential health risk associated with the waters of the Hun-Tai River used for irrigation and drinking.

High Salinity Relay as a Postharvest Processing Strategy To Reduce Vibrio vulnificus Levels in Chesapeake Bay Oysters (Crassostrea virginica)†

2011 ◽  
Vol 74 (11) ◽  
pp. 1902-1907 ◽  
Author(s):  
CORINNE AUDEMARD ◽  
HOWARD I. KATOR ◽  
MARTHA W. RHODES ◽  
THOMAS GALLIVAN ◽  
A. J. ERSKINE ◽  
...  
Keyword(s):  
Chesapeake Bay ◽  
High Salinity ◽  
Vibrio Vulnificus ◽  
Most Probable Number ◽  
Probable Number ◽  
Low Salinity ◽  
Moderate Salinity ◽  
Salinity Increase ◽  
The Impact ◽  
Postharvest Processing

In 2009 the U.S. Food and Drug Administration (FDA) announced its intention to implement postharvest processing (PHP) methods to eliminate Vibrio vulnificus from oysters intended for the raw, half-shell market that are harvested from the Gulf of Mexico during warmer months. FDA-approved PHP methods can be expensive and may be associated with unfavorable responses from some consumers. A relatively unexplored PHP method that uses relaying to high salinity waters could be an alternative strategy, considering that high salinities appear to negatively affect the survival of V. vulnificus. During relay, however, oysters may be exposed to rapid and large salinity increases that could cause increased mortality. In this study, the effectiveness of high salinity relay to reduce V. vulnificus to <30 most probable number (MPN) per g and the impact on oyster mortality were assessed in the lower Chesapeake Bay. Two relay experiments were performed during the summer and fall of 2010. Oysters collected from three grow-out sites, a low salinity site (14 to 15 practical salinity units [psu]) and two moderate salinity sites (22 to 25 psu), were relayed directly to a high salinity site (≥30 psu) on Virginia's Eastern Shore. Oysters were assayed for V. vulnificus and Vibrio parahaemolyticus (another Vibrio species of concern) densities at time 0 prior to relay and after 7 and 14 days of relay, using the FDA MPN enrichment method combined with detection by real-time PCR. After 14 days, both V. vulnificus and V. parahaemolyticus densities were ≤0.8 MPN/g, and decreases of 2 to 3 log in V. vulnificus densities were observed. Oyster mortalities were low (≤<4%) even for oysters from the low salinity harvest site, which experienced a salinity increase of approximately 15 psu. Results, although preliminary and requiring formal validation and economic analysis, suggest that high salinity relay could be an effective PHP method.

scholarly journals Seasonal Variation of Ralstonia solanacearum Biovar 2 Populations in a Spanish River: Recovery of Stressed Cells at Low Temperatures

2005 ◽  
Vol 71 (1) ◽  
pp. 140-148 ◽  
Author(s):  
Paola Caruso ◽  
Jose Luis Palomo ◽  
Edson Bertolini ◽  
Bel�n �lvarez ◽  
Mar�a M. L�pez ◽  
...  
Keyword(s):  
Ralstonia Solanacearum ◽  
Water Samples ◽  
Low Temperatures ◽  
Most Probable Number ◽  
Enzyme Linked Immunosorbent Assay ◽  
Probable Number ◽  
Solid Media ◽  
Nonculturable State ◽  
Enrichment Protocol ◽  
Stressed Cells

ABSTRACT The presence of Ralstonia solanacearum biovar 2 in the watercourses of European countries is increasing, but little is known about its ecology in aquatic habitats. The detection of this pathogen in 2000 in one Spanish river led us to study its population density at different locations on the river over a period of 3 years. During 2000 and 2001, the pathogen was recovered at low densities (10 to 80 CFU/ml) by direct plating on modified SMSA agar from water samples at 14�C or higher, but its isolation was usually unsuccessful at temperatures below 9�C. To monitor the pathogen's abundance in winter, we used two liquid selective media for enrichment (at 29 and 35�C) and compared them by using spiked river water samples: modified Wilbrink broth (MWB) was more efficient than modified SMSA broth for double-antibody-sandwich indirect enzyme-linked immunosorbent assay (DASI-ELISA) detection of R. solanacearum. Enrichment in MWB at both temperatures allowed us to recover R. solanacearum cells that were nonculturable on solid media up to 25 days after their entry into the viable but nonculturable state. When we applied this technique to water samples during the cold months of 2001 and 2002, we obtained the best detection results by the most-probable-number method after enrichment at 35�C with MWB. The enrichment protocol was combined with DASI-ELISA and validated by Co-PCR to detect both naturally and artificially starved and cold-stressed cells in water, which were still infective. Overall, the data from this study demonstrate the effects of temperature variation on the population and culturability of R. solanacearum cells on solid media and their survival at low temperatures.

scholarly journals Antibiotic Susceptibility of Bacteria Isolated from Abattoir Effluent-Impacted Tagangu River, Aliero, Kebbi State, North-Western Nigeria

2019 ◽  
pp. 1-8 ◽  
Author(s):  
B. G. Jega ◽  
O. O. Adebisi ◽  
S. S. Manga
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Antibiotic Susceptibility ◽  
Microbiological Quality ◽  
Most Probable Number ◽  
Resistant Bacteria ◽  
Proteus Vulgaris ◽  
Probable Number ◽  
Antibiotic Susceptibility Test ◽  
The Impact

This study aimed to evaluate the impact of abattoir effluent on microbiological quality of the receiving Tagangu River and the susceptibility of the isolates to commonly-used antibiotics. The most probable number (MPN) as well as the Kirby-Bauer method of antibiotic susceptibility test were used and demonstrated the total heterotrophic bacteria as well as Escherichia coli O157:H7 numbers in a total of 30 water samples collected over a period of three months at three strategic points of the river. In accordance with CLSI guidelines, four out of eight bacteria (Enterobacter sp., Pseudomonas aeruginosa, Proteus vulgaris and Citrobacter sp.) isolated, demonstrated multiple antibiotic resistance (MAR) against at least three out of septrin, chloramphenicol, amoxicillin, augmentin, gentamicin, tarivid and streptomycin. All the isolates (Escherichia coli, Klebsiella pneumoniae, Enterobacter sp., Pseudomonas aeruginosa, Proteus vulgaris, Citrobacter sp., Serratia marcescens and Aerobacter aerogenes) showed either high or intermediate susceptibility to sparfloxacin, ciprofloxacin and pefloxacin. The findings indicated that the river has been heavily polluted with the effluent discharges and did not meet any of the WHO guidelines for natural water sources fit for irrigation or other domestic purposes. As such, indiscriminate discharge of abattoir effluent could impact on the microbiological quality and promote increased incidence of multiple antibiotic resistant bacteria in a receiving river.

Monitoring of E. coli and Enterococci in Lake Michigan Beach Sand

2020 ◽  
Author(s):  
Jin Li ◽  
Brett Bevers ◽  
Nabila Nafsin ◽  
Qian Liao
Keyword(s):  
Water Quality ◽  
Lake Michigan ◽  
Indicator Bacteria ◽  
Beach Sand ◽  
Most Probable Number ◽  
Probable Number ◽  
E Coli ◽  
Sampling Duration ◽  
The Impact ◽  
Mean Concentration

<p>Excessive fecal indicator bacteria concentration leads to swimming advisories that are very common to freshwater beaches. To evaluate the concentration and interaction of indicator bacteria in beach sand and water and to examine the factors that affect bacteria concentration, a study was undertaken at Bradford beach, Milwaukee county on the shore of Lake Michigan. In this research, results from monitoring of E. coli and Enterococci in sand and water from Lake Michigan beach were presented. Bacteria counts were obtained using the IDEXX Most Probable Number (MPN) method. An attempt was made to establish a direct ratio of bacteria counts between the two most common eluents used to detach bacteria from sand, i.e., deionized water (DI) and phosphate buffered saline (PBS). The beach sand bacteria count was analyzed using the EPA CANARY event detection software to identify the onset of periods of anomalous water quality. Analysis of beach sand from this study show that for E. coli, it may be possible to establish a relationship between the results generated using two eluents. Results from the model indicates that sand can be a better potential reservoir for indicator bacteria survival than water as a source. The results also show that CANARY may be useful as an early warning system for monitoring beach contamination and may help to identify any abnormal condition very quickly. Also, in this study, the factors that contributed to the high concentration of bacteria resulting in abnormal water quality events are examined which are the impact of Algae in beach water sample and the rainfall effect during the overall month of sampling duration. CANARY software can best indicate the impact of the presence of Algae on bacteria concentration. The analysis of rainfall effect on bacteria concentration was done using statistical software by determining the significance (p-value) between the seasonal mean concentration of E. coli and the mean concentration of E. coli during the sampling duration and from the analyses it is evaluated that rainfall does affect the bacteria concentration. Moreover, the correlation coefficient indicates greater impact of rainfall event on bacteria concentration relative to the presence of Algae level. Regression analysis was also done to estimate the best model that describes the relation between E. coli and water temperature resulting in weak negative linear relationship between the variables.</p>

scholarly journals Environmental impact on the bacteriological quality of domestic water supplies in Lagos, Nigeria

2002 ◽  
Vol 36 (4) ◽  
pp. 513-520 ◽  
Author(s):  
L Egwari ◽  
O O Aboaba
Keyword(s):  
Town Planning ◽  
Enteric Pathogens ◽  
Most Probable Number ◽  
Domestic Water ◽  
Water Supplies ◽  
Probable Number ◽  
Bacteriological Quality ◽  
Shallow Wells ◽  
The Impact

OBJECTIVE: To assess the impact of town planning, infrastructure, sanitation and rainfall on the bacteriological quality of domestic water supplies. METHODS: Water samples obtained from deep and shallow wells, boreholes and public taps were cultured to determine the most probable number of Escherichia coli and total coliform using the multiple tube technique. Presence of enteric pathogens was detected using selective and differential media. Samples were collected during both periods of heavy and low rainfall and from municipalities that are unique with respect to infrastructure planning, town planning and sanitation. RESULTS: Contamination of treated and pipe distributed water was related with distance of the collection point from a utility station. Faults in pipelines increased the rate of contamination (p<0.5) and this occurred mostly in densely populated areas with dilapidated infrastructure. Wastewater from drains was the main source of contamination of pipe-borne water. Shallow wells were more contaminated than deep wells and boreholes and contamination was higher during period of heavy rainfall (p<0.05). E. coli and enteric pathogens were isolated from contaminated supplies. CONCLUSIONS: Poor town planning, dilapidated infrastructure and indiscriminate siting of wells and boreholes contributed to the low bacteriological quality of domestic water supplies. Rainfall accentuated the impact.

scholarly journals Assessment of Recycling-derived Fertilizers as an Alternative to Mineral Fertilizers – Effects on the Soil Microbiome

2020 ◽  
Vol 2 (7A) ◽  
Author(s):  
Lea Deinert ◽  
Israel Ikoyi ◽  
Achim Schmalenberger
Keyword(s):  
Mineral Fertilizer ◽  
Fertilizer Application ◽  
Soil Microbiome ◽  
Most Probable Number ◽  
Mineral Fertilizers ◽  
Probable Number ◽  
Soil P ◽  
Pot Trial ◽  
Living Organisms ◽  
The Impact

Phosphorus (P) is an essential macronutrient for all living organisms and is applied as fertilizer in agroecosystems to improve crop growth. Recycling-derived fertilizers (RDFs) have been developed for nutrient recovery from Europe’s largest waste streams as a sustainable alternative to this finite resource. The impact of four RDFs (two ashes, two struvites) on the soil microbiome in comparison with a P-free control and triple super phosphate (TSP) as mineral fertilizer was investigated in a pot trial and a subsequent microcosm trial (subset of samples). For both experiments perennial ryegrass was cultivated for 54 days. The pot trial was conducted at P fertilization rates of 20 and 60 kg P ha-1 in quadruplicates. After the pot harvest the bulk soil was stored until the microcosm trial was conducted, using the control, TSP and the two ashes at 60 kg P ha-1 in six replicates. Pot trial results showed highest P bioavailability from struvites at high P rates, also resulting in higher biomass yield on average. Furthermore, P solubilization capabilities from tri-calcium phosphate was enhanced in the RDFs treatments, while the TSP treatments were negatively affected. For the microcosm trial, most probable number (MPN) analysis showed that phytate-utilizing bacterial abundance was significantly increased in one of the ashes and had also remained higher in the RDF treatments after storage. Understanding the effects of recycling-derived fertilizer application on the soil P cycle is vital for developing a more sustainable agriculture.

Microbiological Food Safety Status of Commercially Produced Tomatoes from Production to Marketing

2016 ◽  
Vol 79 (3) ◽  
pp. 392-406 ◽  
Author(s):  
BRIGITTE N. van DYK ◽  
WILLEKE de BRUIN ◽  
ERIKA M. du PLESSIS ◽  
LISE KORSTEN
Keyword(s):  
Food Safety ◽  
Salmonella Typhimurium ◽  
Contact Surface ◽  
Personal Hygiene ◽  
Most Probable Number ◽  
Source Water ◽  
Probable Number ◽  
E Coli ◽  
Processing Facility ◽  
The Impact

ABSTRACT Tomatoes have been implicated in various microbial disease outbreaks and are considered a potential vehicle for foodborne pathogens. Traceback studies mostly implicate contamination during production and/or processing. The microbiological quality of commercially produced tomatoes was thus investigated from the farm to market, focusing on the impact of contaminated irrigation and washing water, facility sanitation, and personal hygiene. A total of 905 samples were collected from three large-scale commercial farms from 2012 through 2014. The farms differed in water sources used (surface versus well) and production methods (open field versus tunnel). Levels of total coliforms and Escherichia coli and prevalence of E. coli O157:H7 and Salmonella Typhimurium were determined. Dominant coliforms were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. No pathogens or E. coli were detected on any of the tomatoes tested throughout the study despite the high levels of coliforms (4.2 to 6.2 log CFU/g) present on the tomatoes at the market. The dominant species associated with tomatoes belonged to the genera Enterobacter, Klebsiella, and Citrobacter. Water used on the farm for irrigation considered not fit for purpose according to national agricultural irrigation standards, with high E. coli levels resulting from either a highly contaminated source water (river water at 3.19 log most probable number [MPN]/100 ml) or improper storage of source water (stored well water at 1.72 log MPN/100 ml). Salmonella Typhimurium was detected on two occasions on a contact surface in the processing facility of the first farm in 2012. Contact surface coliform counts were 2.9 to 4.8 log CFU/cm2. Risk areas identified in this study were water used for irrigation and poor sanitation practices in the processing facility. Implementation of effective food safety management systems in the fresh produce industry is of the utmost importance to ensure product safety for consumers.

Environmental Dust Exposure as a Factor Contributing to an Increase in Escherichia coli O157 and Salmonella Populations on Cattle Hides in Feedyards

2008 ◽  
Vol 71 (10) ◽  
pp. 2078-2081 ◽  
Author(s):  
M. F. MILLER ◽  
G. H. LONERAGAN ◽  
D. D. HARRIS ◽  
K. D. ADAMS ◽  
J. C. BROOKS ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Positive Sample ◽  
Dust Exposure ◽  
Most Probable Number ◽  
Escherichia Coli O157 ◽  
Probable Number ◽  
Airborne Dust ◽  
E Coli ◽  
Dust Generation ◽  
The Impact

A study was conducted to determine the impact of exposure to dust in the cattle load-out area in feedyards on pathogen contamination of cattle hides. A total of 250 cattle hides were sampled during summer and fall months, which are associated with elevated prevalence of Escherichia coli O157 in West Texas. Animals were removed from their home pens and restrained in a chute and sampled prior to exposure to dust generated as a result of a simulated loading exercise. The cattle hides were sampled again after exposure to the loading dust to determine total numbers of pathogens on cattle hides on leaving their home pen (before loading) and on cattle hides after exposure to the dust in the loading area. Air and dirt samples from the home pens and the cattle load-out area were also collected. The presence of E. coli O157 and Salmonella was determined in all the samples, and when a positive sample was identified, the total numbers of these bacteria present were enumerated. The total numbers of pathogens increased after dust exposure; Salmonella counts increased from 1.09 log most probable number (MPN)/cm2 to 1.74 log MPN/cm2 after exposure, and E. coli O157 counts increased from 0.80 to 2.35 log MPN/cm2 after sampling. E. coli O157 and Salmonella were recovered from the air samples during dust generation at 6.66 and 11.1%, respectively. Salmonella and E. coli O157 prevalence was not changed and was not associated with the exposure to the dust. Results indicate airborne dust generated as a result of cattle movement and loading could be an important determining factor in total numbers of pathogens recovered on cattle hides.

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