scholarly journals Selenite Cystine Agar for Enumeration of Inoculated Salmonella Serovars Recovered from Stressful Conditions during Antimicrobial Validation Studies

2020 ◽  
Vol 8 (3) ◽  
pp. 338 ◽  
Author(s):  
Caitlin E. Karolenko ◽  
Arjun Bhusal ◽  
Dhiraj Gautam ◽  
Peter M. Muriana
Keyword(s):  
Antibiotic Resistance ◽  
Foodborne Pathogens ◽  
Validation Studies ◽  
Salmonella Enteritidis ◽  
Acid Stress ◽  
Selective Medium ◽  
Selective Media ◽  
Selective Enrichment ◽  
Salmonella Hadar ◽  
Salmonella Serovars

Process validation studies often require the inoculation of select foodborne pathogens into targeted foods to determine the lethality of the process or antimicrobial ingredients, and quantitative recovery of surviving inoculum bacteria helps to make those assessments. Such processes introduce various stressors on the inoculated challenge microorganisms whereby traditional selective media are too harsh to enumerate the remaining viable and injured population quantitatively. Innate antibiotic resistance of challenge organisms has often been used to establish simple selective media (i.e., Tryptic Soy Agar/TSA + antibiotics) for recovering inoculated strains, but sometimes antibiotic resistant background microorganisms are higher than desired. Salmonella Thompson 120, Salmonella Heidelberg F5038BG1, Salmonella Hadar MF60404, Salmonella Enteritidis H3527, and Salmonella Typhimurium H3380 were characterized for antibiotic resistance and acid adaptation in Tryptic Soy Broth containing 0%, 0.25%, or 1.0% glucose. Sodium pyruvate was evaluated for recovery after stress but no enhancing effect was observed, possibly because the strains were acid-adapted. Selenite Cystine Broth, traditionally used as a selective enrichment broth, was used as the basis for Selenite Cystine Agar (SCA) in combination with three antibiotics to which our Salmonella are resistant. Serovars of Salmonella, both individually and in mixtures, were enumerated on TSA, SCA, Xylose Lysine Desoxycholate (XLD), and Hektoen Enteric (HE) selective agars (all containing the same antibiotics) after conditions of nutrient starvation, desiccation, acid stress, and thermal stress. The data show that quantitative enumeration of our Salmonella serovars on SCA was not significantly different (p > 0.05) than those achieved on TSA for all tested stress categories. Levels of Salmonella enumerated on XLD and/or HE were significantly different (p < 0.05) than on TSA and SCA and often more than 1–2-log lower, consistent with the inhibition of injured cells. These data confirm that SCA (+ antibiotics) is a suitable selective medium for enumeration of these acid-adapted Salmonella serovars as challenge organisms recovered from various conditions of stress.

scholarly journals Virulence genotypes of clinical SalmonellaSerovars from broilers in Egypt

2016 ◽  
Vol 10 (04) ◽  
pp. 337-346 ◽  
Author(s):  
Ahmed Mohamed Ammar ◽  
Adel Attia Mohamed ◽  
Marwa Ibrahim Abd El-Hamid ◽  
Mona Mohamed El-Azzouny
Keyword(s):  
Antibiotic Resistance ◽  
Foodborne Pathogens ◽  
Broiler Chickens ◽  
Virulence Gene ◽  
Distribution Patterns ◽  
Gene Profiling ◽  
Virulence Determinants ◽  
Resistance Patterns ◽  
Microbiological Techniques ◽  
Salmonella Serovars

Introduction: Salmonella serovars are one of the primary foodborne pathogens. Poultry consumption is responsible for the majority of disease cases worldwide. The prevalence of virulence determinants among Salmonella serovars appears to be lacking in Egypt. Therefore, this study investigated the occurrence, antibiotic resistance patterns, and virulence gene profiling of Salmonella serovars in broilers. Methodology: Three hundred samples from broiler chickens were examined for the presence of Salmonella by standard microbiological techniques. All Salmonella isolates were tested for their sensitivity against ten antibiotics and subjected to virulence genotyping by polymerase chain reaction (PCR). Results: The overall isolation percentage of Salmonella was 17%. Seven different serovars were found, with the main one being Salmonella Typhimurium (52.94%). Salmonella isolates were sensitive to most of the tested antibiotics, but they exhibited absolute resistance against amoxicillin/clavulanic acid. Nine Salmonella strains (52.94%) were resistant to at least three antibiotics. Further PCR investigations into 17 Salmonella strains revealed different distribution patterns of eight virulence determinants among the isolates. The invA gene was the most prevalent one (100%), followed by hilA (88.24%), stn (58.82%), and fliC genes (52.94%), while each of sopB and pefA genes had a similar prevalence (41.18%), and sefC and spvC genes had the lowest prevalence (11.76 and 5.88%, respectively). PCR genotyping allowed grouping of Salmonella strains into ten genetic profiles. Conclusions: These results will help in understanding the spread of virulence genotypes and antibiotic resistance among Salmonella serovars in broilers.

Evaluation of Thin Agar Layer Method for Recovery of Acid-Injured Foodborne Pathogens†

2001 ◽  
Vol 64 (7) ◽  
pp. 1067-1071 ◽  
Author(s):  
V. C. H. WU ◽  
D. Y. C. FUNG ◽  
D. H. KANG ◽  
L. K. THOMPSON
Keyword(s):  
Foodborne Pathogens ◽  
Petri Dish ◽  
Selective Medium ◽  
Escherichia Coli O157 ◽  
Selective Media ◽  
Layer Method ◽  
Significant Difference ◽  
Selective Agents ◽  
One Step ◽  
Agar Layer

The thin agar layer (TAL) method of Kang and Fung was used to enumerate acid-injured foodborne pathogens. This method involves overlaying 14 ml of nonselective medium (tryptic soy agar [TSA]) onto a prepoured and solidified pathogen-specific, selective medium in a petri dish. After surface plating, injured cells resuscitated and grew on TSA during the first few hours of incubation; then, the selective agents from the selective medium diffused to the top layer, interacted with the recovered microorganisms, and started to produce typical reactions. Foodborne pathogens were exposed to 2% acetic acid for 1, 2, or 4 min, and the recovery rate with the TAL method was compared with the rate of TSA and pathogen-specific, selective media. No significant difference occurred between TSA and TAL (P &gt; 0.05) for enumeration of acid-injured Escherichia coli O157:H7, Salmonella Typhimurium, Staphylococcus aureus, and Yersinia enterocolitica, and both recovered significantly higher numbers than the selective medium for each respective pathogen (P &lt; 0.05). For recovery of acid-injured Listeria monocytogenes, no difference (P &gt; 0.05) occurred among TSA, TAL, and selective media. However, fewer cells were recovered in the selective media. The TAL method is a one-step, convenient procedure for recovery of acid-injured cells.

Presence and Distribution of Salmonella Species in some Local Foods from Baghdad City, Iraq

1979 ◽  
Vol 42 (11) ◽  
pp. 877-880 ◽  
Author(s):  
NASSIR AL-HINDAWI ◽  
RIHAB RISHED
Keyword(s):  
Salmonella Typhimurium ◽  
Salmonella Enteritidis ◽  
Brilliant Green ◽  
Food Samples ◽  
Selective Medium ◽  
Local Foods ◽  
Selective Enrichment ◽  
Paratyphi B ◽  
First Time ◽  
Salmonella Senftenberg

A total of 353 local food samples were cultured for Salmonella species using mannitol broth and two selective enrichment media, tetrathionate brilliant green bile broth and selenite cystine broth. Fifteen Salmonella species and serotypes were isolated: Salmonella paratyphi B. Salmonella typhimurium, Salmonella 4,5,12:-:-. Salmonella muenchen, Salmonella senftenberg, Salmonella lille, Salmonella alachua, Salmonella 6,7:-:-. Salmonella anatum, Salmonella enteritidis, Salmonella havana, Salmonella eppendorf, Salmonella emek, Salmonella california, and Salmonella 1.3.19:-:-. Salmonella was recovered from 27% of food samples examined. The occurrence of some species was as high as 11% of the samples. S. lille and S. alachua were isolated and are reported for the first time in Iraq. Seventy food samples (19.8%) harbored one type of Salmonella. 11 (5.9%) harbored two types and four (1.1%) harbored three types. Isolation of Salmonella from foods is affected by types of enrichment media. Tetrathionate brilliant green bile broth was superior to selenite cystine for Salmonella recovery from most foods. Some species prefer certain enrichment media for growth and multiplication. Use of more than one type of selective medium increases the chance of isolation of more Salmonella species and serotypes.

Persistence and Growth of Different Salmonella Serovars on Pre- and Postharvest Tomatoes

2007 ◽  
Vol 70 (12) ◽  
pp. 2725-2731 ◽  
Author(s):  
X. SHI ◽  
A. NAMVAR ◽  
M. KOSTRZYNSKA ◽  
R. HORA ◽  
K. WARRINER
Keyword(s):  
Salmonella Enteritidis ◽  
Incubation Temperature ◽  
Narrow Range ◽  
Tomato Fruit ◽  
Diverse Range ◽  
Salmonella Dublin ◽  
Salmonella Newport ◽  
Salmonella Hadar ◽  
Salmonella Serovars ◽  
Salmonella Senftenberg

The interaction of a range of Salmonella serovars with pre- and postharvest tomatoes was evaluated. Serovars were selected on the basis of previous association in tomato-linked outbreaks of salmonellosis (Salmonella Javiana, Salmonella Montevideo, and Salmonella Newport) or those typically isolated from animal or clinical infections (Salmonella Dublin, Salmonella Enteritidis, Salmonella Hadar, Salmonella Infantis, Salmonella Typhimurium, and Salmonella Senftenberg). Salmonella serovars introduced onto the flowers of growing plants were recovered on and within the developing tomato fruit. Of all the Salmonella serovars tested, Montevideo appeared to be more adapted to survival within tomatoes and was recovered from 90% of the fruit screened. All of the Salmonella serovars could persist and grow when introduced onto unripened (green) tomato fruit. In general, growth (internal and external) was promoted at the high incubation temperature (25°C) and high relative humidity (95%), although this was serovar dependent. The growth and persistence of Salmonella introduced on and into ripened (red) tomatoes was serovar dependent. Salmonella serovars Enteritidis, Typhimurium, and Dublin were less adapted to grow in or on intact red tomatoes than were serovars Hadar, Montevideo, or Newport. The results illustrated that a diverse range of Salmonella serovars can become established within and/or on preharvest tomatoes. The majority of Salmonella can grow and become established both on and within unripened tomatoes, but growth on ripened fruit was serovar dependent. The results provide a possible explanation why only a narrow range of Salmonella serovars are associated with foodborne illness outbreaks linked to tomatoes.

Prevalence and Dissemination of Salmonella Serotypes along the Slaughtering Process in Brazilian Small Poultry Slaughterhouses

2000 ◽  
Vol 63 (12) ◽  
pp. 1749-1753 ◽  
Author(s):  
TERUMI O. FUZIHARA ◽  
SUELI A. FERNANDES ◽  
BERNADETTE D. G. M. FRANCO
Keyword(s):  
Salmonella Enteritidis ◽  
Control Measures ◽  
Poultry Meat ◽  
Effective Control ◽  
Salmonella Spp ◽  
Selective Enrichment ◽  
Peptone Water ◽  
Salmonella Hadar ◽  
Salmonella Serotypes ◽  
Biochemical Testing

Salmonella is the leading cause of human foodborne infections in Latin America, and poultry meat is one of the main vehicles. Small poultry slaughterhouses (fewer than 200 birds slaughtered per day) represent an important economic activity in certain regions. The slaughtering process in these abattoirs is manual and rudimentary, and frequently the hygienic conditions are poor. This study reports results of a detailed evaluation of the prevalence of Salmonella serotypes in carcasses, utensils, and environmental samples collected in 60 small Brazilian slaughterhouses. In the second step of the study, one of these slaughterhouses was selected to monitor the dissemination of Salmonella along the slaughtering process. For testing, conventional procedures were used: preenrichment in buffered peptone water (35°C for 24 h), selective enrichment in Selenite-cystine (35°C for 24 h), tetrathionate and Rappaport-Vassiliadis broths (42°C for 24 h), plating on bismuth-sulfite and brilliant green agars (35°C for 24 h), proper biochemical testing, and complete serotyping. Forty-one percent of samples harbored Salmonella spp., including 42% of carcasses, 23.1% of utensils, 71.4% of water, and 71.4% of freezers and refrigerators. Seventeen serotypes were detected. Salmonella Enteritidis predominated (30%), followed by Salmonella Albany (12%), Salmonella Hadar (12%), Salmonella Indiana (10%), and I 4,12:z:–(8%). All samples collected along the slaughtering process in the selected slaughterhouse were Salmonella positive. Five serotypes were detected, including Salmonella Albany, Salmonella Hadar, Salmonella Agona, Salmonella Emek, and Salmonella Indiana. More than 30% of the samples contained more than one serotype, and 12.5% presented three serotypes. The widespread occurrence of Salmonella in small slaughterhouses reinforces the need for implementation of effective control measures.

scholarly journals Isolation, Identification, and Antibiotic Susceptibility Testing of Salmonella Isolated from Foodborne Outbreaks

2020 ◽  
Vol 8 (3) ◽  
pp. 80-83
Author(s):  
Mohammad Mehdi Soltan Dallal ◽  
Milad Abdi ◽  
Mahya Khalilian ◽  
Zahra Rajabi ◽  
Ronak Bakhtiari ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Antibiotic Susceptibility ◽  
Salmonella Enteritidis ◽  
Its Region ◽  
Detection Methods ◽  
Diffusion Method ◽  
Antimicrobial Susceptibility Pattern ◽  
Resistance Patterns ◽  
Foodborne Outbreaks ◽  
Salmonella Serovars

Background: Foodborne diseases are a major problem worldwide. The epidemiological investigations in many parts of the world have shown an increase in infections caused by Salmonella serovars. Furthermore, the emergence of drug resistance among them has become a major global concern and awareness of the resistance patterns of Salmonella could be very useful in treatment of diseases. Objective: This study aimed to investigate Salmonella serotypes in foodborne outbreaks by sequencing of ITS region of 16S-23SrRNA gene and to determine their antimicrobial susceptibility pattern. Materials and Methods: A total of 614 diarrheal stool samples were collected from 173 foodborne outbreaks in different provinces of Iran during one year. Identification of Salmonella was carried out by phenotypic and molecular (16s-23srRNA gene detection) methods and antibiotic susceptibility was performed using disc diffusion method. Results: Out of 614 samples, 18 isolates were identified as Salmonella of which 16 (88.9%) isolates were Salmonella Enteritidis and 2 (11.1%) isolates as Salmonella Paratyphi A. All isolates were sensitive to ceftazidime, and high resistance was seen with nalidixic acid with 14 (77.8%) isolates. Conclusion: Increasing antibiotic resistance in many bacterial pathogens such as Salmonella has been a major threat for human health. Therefore, identifying the antibiotic resistance patterns of Salmonella serovars may help in treatment of the associated infections.

Use of gene probes for the detection of quiescent enteric bacteria in marine and fresh waters

1995 ◽  
Vol 31 (5-6) ◽  
pp. 291-298
Author(s):  
Sally A. Anderson ◽  
Gillian D. Lewis ◽  
Michael N. Pearson
Keyword(s):  
Membrane Filtration ◽  
Enteric Bacteria ◽  
Probe Method ◽  
Detection Methods ◽  
23S Rrna ◽  
Specific Gene ◽  
Gene Probe ◽  
Selective Media ◽  
Selective Enrichment ◽  
E Coli

Specific gene probe detection methods that utilise a non-selective culturing step were tested for the ability to recognise the presence of quiescent enteric bacteria (Escherichia coli and Enterococcus faecalis ) within illuminated freshwater and seawater microcosms. An E. coli specific uidA gene probe and a 23S rRNA oligonucleotide probe for Enterococci were compared with recoveries using membrane filtration and incubation on selective media (mTEC and mE respectively). From these microcosm experiments a greater initial detection (from 4 hours to 1 day) of E. coli and Ent. faecalis using gene probe methods was observed. Additionally, a comparison of E. coli direct viable counts (DVC) in sunlight exposed microcosms with recoveries by selective media and gene probe methods revealed a large number of viable non-culturable cells. This suggests that enumeration of E. coli by a gene probe method is limited by the replication of the bacteria during the initial non-selective enrichment step. The detection of stressed Ent. faecalis by the oligonucleotide gene probe method was significantly greater than recovery on selective mE agar, indicating an Enterococci non-growth phase.

Comparison of a Real-Time PCR Method with a Culture Method for the Detection of Salmonella enterica Serotype Enteritidis in Naturally Contaminated Environmental Samples from Integrated Poultry Houses

2012 ◽  
Vol 75 (4) ◽  
pp. 743-747 ◽  
Author(s):  
BWALYA LUNGU ◽  
W. DOUGLAS WALTMAN ◽  
ROY D. BERGHAUS ◽  
CHARLES L. HOFACRE
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Salmonella Enteritidis ◽  
Culture Method ◽  
Pcr Assay ◽  
Culture Methods ◽  
The Real ◽  
Selective Enrichment ◽  
Conventional Culture ◽  
Field Samples

Conventional culture methods have traditionally been considered the “gold standard” for the isolation and identification of foodborne bacterial pathogens. However, culture methods are labor-intensive and time-consuming. A Salmonella enterica serotype Enteritidis–specific real-time PCR assay that recently received interim approval by the National Poultry Improvement Plan for the detection of Salmonella Enteritidis was evaluated against a culture method that had also received interim National Poultry Improvement Plan approval for the analysis of environmental samples from integrated poultry houses. The method was validated with 422 field samples collected by either the boot sock or drag swab method. The samples were cultured by selective enrichment in tetrathionate broth followed by transfer onto a modified semisolid Rappaport-Vassiliadis medium and then plating onto brilliant green with novobiocin and xylose lysine brilliant Tergitol 4 plates. One-milliliter aliquots of the selective enrichment broths from each sample were collected for DNA extraction by the commercial PrepSEQ nucleic acid extraction assay and analysis by the Salmonella Enteritidis–specific real-time PCR assay. The real-time PCR assay detected no significant differences between the boot sock and drag swab samples. In contrast, the culture method detected a significantly higher number of positive samples from boot socks. The diagnostic sensitivity of the real-time PCR assay for the field samples was significantly higher than that of the culture method. The kappa value obtained was 0.46, indicating moderate agreement between the real-time PCR assay and the culture method. In addition, the real-time PCR method had a turnaround time of 2 days compared with 4 to 8 days for the culture method. The higher sensitivity as well as the reduction in time and labor makes this real-time PCR assay an excellent alternative to conventional culture methods for diagnostic purposes, surveillance, and research studies to improve food safety.

Screening of Commercial and Pecan Shell–Extracted Liquid Smoke Agents as Natural Antimicrobials against Foodborne Pathogens

2012 ◽  
Vol 75 (6) ◽  
pp. 1148-1152 ◽  
Author(s):  
ELLEN J. VAN LOO ◽  
D. BABU ◽  
PHILIP G. CRANDALL ◽  
STEVEN C. RICKE
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogens ◽  
Salmonella Enteritidis ◽  
Antioxidant Properties ◽  
Inhibitory Effects ◽  
Natural Antimicrobials ◽  
E Coli ◽  
Liquid Smoke ◽  
Water Based ◽  
Smoke Sample

Liquid smoke extracts have traditionally been used as flavoring agents, are known to possess antioxidant properties, and serve as natural alternatives to conventional antimicrobials. The antimicrobial efficacies of commercial liquid smoke samples may vary depending on their source and composition and the methods used to extract and concentrate the smoke. We investigated the MICs of eight commercial liquid smoke samples against Salmonella Enteritidis, Staphylococcus aureus, and Escherichia coli. The commercial liquid smoke samples purchased were supplied by the manufacturer as water-based or concentrated extracts of smoke from different wood sources. The MICs of the commercial smokes to inhibit the growth of foodborne pathogens ranged from 0.5 to 6.0% for E. coli, 0.5 to 8.0% for Salmonella, and 0.38 to 6% for S. aureus. The MIC for each liquid smoke sample was similar in its effect on both E. coli and Salmonella. Solvent-extracted antimicrobials prepared using pecan shells displayed significant differences between their inhibitory concentrations depending on the type of solvent used for extraction. The results indicated that the liquid smoke samples tested in this study could serve as effective natural antimicrobials and that their inhibitory effects depended more on the solvents used for extraction than the wood source.

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