Xylose Lysine Desoxycholate Agar Research Articles

Peroxyacetic Acid Effectiveness against Salmonella on Raw Poultry Parts Is Not Affected by Organic Matter

Organic matter (OM) accumulation is common in chill tanks used to decontaminate raw poultry parts during processing. OM negatively affects the antimicrobial activity of chlorine-based compounds, but its effect on the antimicrobial effectiveness of peroxyacetic acid (PAA) on poultry meat has not been described. Therefore, this study evaluated the effect of OM on the efficacy of PAA solutions in simulated postchill tanks to reduce Salmonella artificially inoculated onto chicken parts. Chicken thighs were inoculated with a five-strain cocktail of poultry-borne Salmonella enterica serovars at ca. 6 log CFU/mL. Then, the thighs were immersed for 30 or 45 s in PAA solutions (500 or 1,000 ppm) with chicken slurry to simulate OM accumulation (0, 15, or 30 g/L). The thighs were rinsed with neutralizing buffered peptone water (100 mL), and rinsates were plated onto xylose lysine desoxycholate agar. Experiments were performed in triplicate (three thighs per treatment per replicate). Chemical oxygen demand, total nitrogen, and pH were measured as the water quality parameters of the PAA solutions before and after use. Chemical oxygen demand ranged from 2,905 mg/L in unused 500-ppm solutions without added OM to 6,290 mg/L in used 1,000-ppm solutions with 30 g/L OM. Initial total nitrogen was 42.5 ± 2.0 and 60.9 ± 8.3 mg/L for 15 and 30 g/L OM, which increased by 27 ± 17 mg/L after use. The pH of solutions ranged from 3.16 ± 0.14 to 3.42 ± 0.09 for the 1,000-ppm solutions and from 3.59 ± 0.06 to 3.96 ± 0.06 for the 500-ppm solutions. Mean Salmonella reductions were 0.9 ± 0.1 log CFU/mL of rinsate for the 500-ppm PAA treatment and 1.1 ± 0.1 log CFU/mL of rinsate for 1,000-ppm PAA treatment. Exposure time did not have a significant effect on the logarithmic reductions. There was no significant effect of OM concentration (P > 0.05) on the reductions, indicating that the antimicrobial efficacy was not affected and that PAA solutions may continue to be reused as long as the PAA concentration is actively monitored.

Extended Spectrum Beta-Lactamase (ESBL) Resistant genes in Salmonella species Isolated from Ready-to-eat Foods and Food Handlers in Port Harcourt Metropolis, Nigeria

Aim: To assess the Extended Spectrum Beta-Lactamase (ESBL) resistant genes in Salmonella spp isolated from ready-to-eat foods and food handlers in Port Harcourt Metropolis, Nigeria.
 Study Design: A cross-sectional study.
 Place and Duration of Study: This study was conducted in selected places in Port Harcourt, between November 2019 and June 2021.
 Methodology: A total of 350 food specimens and 230 food handlers were collected and the social demographic information were collected using a questionnaire survey. The samples were analysed for contamination with Salmonella species using conventional and molecular methods. Salmonella species were isolated from samples using Salmonella-Shigella agar (SSA), Xylose-lysine desoxycholate agar (XLD), MacConkey agar (MA), Blood agar (BA) after pre-enrichment and enrichment method has been done using peptone water broth and Selenite F. Salmonella Chromogenic medium (SCM) was also used to confirm the isolate. Antibiotic susceptibility patterns of the Salmonella isolates were determined using Kirby Bauer disk diffusion method. The presence of Extended Spectrum Beta Lactamase genes (CTX-M, SHV, and TEM) in the Salmonella isolates were screened using double disc synergy method and also investigated using Polymerase chain reaction (PCR) technique.
 Results: Results showed that of the 11 Salmonella species isolated from the food handlers, 7(63.6%) harboured extended spectrum beta-lactamase (ESBL) genes while 18 (64.3%) out of 28 Salmonella isolated from street vended food sample were positive for ESBL genes. However, there was no significant difference in the proportion of ESBL producers observed in the street vended food and those in food handlers’ sample (P= 0.964) PCR result revealed the presence of genes encoding for TEM, SHV and CTX-M.
 Conclusion: Street vended foods such as white rice/stew, jollof rice, rice/beans stew, porridge beans, beans/stew, moi moi, abacha, and roasted plantain in Port Harcourt harbour Salmonella species that possess the following Extended Spectrum Beta Lactamase (ESBL) genes as CTX-M, SHV and TEM. This should receive particular attention, as the presence of extended spectrum beta-lactamase genes isolated, indicate public health hazard and gives a warning signal for the possible occurrence of food borne diseases and multi-drug resistance.

Prevalence and Antimicrobial Susceptibility of Salmonella spp Isolated from Ready-to-eat foods and Food Handlers in Port Harcourt Metropolis, Nigeria

Aim: To assess the prevalence and antimicrobial susceptibility of Salmonella species isolated from ready-to-eat foods and food handlers in Port Harcourt Metropolis, Nigeria.
 Study Design: Cross-sectional study
 Place and Duration of Study: This study was conducted in selected places in Port Harcourt, between November 2019 and June 2021.
 Methodology: A total of 350 food specimens and 230 food handlers’ specimens were collected. The following street vended food were analysed: White rice/stew, Jollof rice, Rice/beans stew, Porridge beans, Beans/stew, Moi Moi, Africa salad and Roasted plantain. The social demographic information was collected using a questionnaire survey. The samples were analysed for contamination with Salmonella species using conventional protocol. Salmonella species were isolated from samples using Salmonella-Shigella agar (SSA), Xylose-lysine desoxycholate agar (XLD), MacConkey agar (MA), Blood agar (BA) after pre-enrichment and enrichment method has been done using peptone water broth and selenite F broth. Salmonella Chromogenic medium (SCM) was also used to confirm the isolate. Antibiotic susceptibility patterns of the Salmonella isolates were determined using Kirby Bauer disk diffusion method. Data collected was analyzed with the Statistical Package for Social Sciences (SPSS, V25, IBM, USA). The prevalence and distribution of Salmonella sp and antibiotic resistance patterns were presented in frequencies and percentages. All analysis was done at a 95% confidence interval and p-values less than 0.05 were considered significant.
 Results: The prevalence of Salmonella species in the street vended foods was 8.2% and 4.8% among the food handlers. However, there was no statistically significant difference in the proportion of Salmonella growth observed in street vended food and food handlers (P= 0.2900). The isolates from street vended foods and handlers were susceptible to Sulfamethioxazole/Trimetoprin and Meropeneme and resistant to Amoxiclave, Ceftiaxone, Ampicillin, Cefotaxime, Ceftazidine, Levofloxacin and Tetracycline. 
 Conclusion: Salmonella isolates identified from the samples and their handlers showed susceptibility to ciprofloxacin, erythromycin, gentamicin, meropenem, sulfamethroxazole/ Trimethoprim with more isolates being sensitive to meropenem. However, they were resistant to amoxiclav, ceftazidine, cefotaxime, levofloxacin and ceftriaxone.

Pathogenic Bacterial Flora of Raw Chicken Eggs Sold in Jos, Plateau State, Nigeria

Eggs are an important component of the diets of increasing numbers of Nigerians and are used in a number of foods such as salad dressings and home-made creams. Jos, Plateau State, Nigeria is an important source of eggs consumed in Nigeria. However, most eggs in Jos are produced by subsistence poultry farmers with poor regard for hygienic practices. To determine the bacterial load and hence sanitary health quality of eggs sold and consumed, 100 eggs were randomly sampled from egg vendors in twenty locations of Jos North, Jos South and Jos East municipalities. Dilutions of egg shell washes and egg contents were cultured on Nutrient, and subcultured on McConkey agar and Xylose Lysine Desoxycholate (XLD) agar. All egg surfaces (shells) sampled had CFUs ranging between 1.0 x 106 - 1.1 x 108/mL in Jos East, 4.3 x 105 – 6.0 x 107/mL in Jos South and 3.4 x 105 – 1.1 x 108/mL in Jos North respectively. While ANOVA and t-test showed no statistically significant differences (p>0.05) in bacterial counts from within sample locations, Chi Square (χ2) showed association (p<0.05) between bacterial counts and sample locations; Mean counts 1.06 x 109, 1.32 x 108 and 5.11 x 107 per mL respectively in Jos North, Jos East and Jos South. Eggs with bacteria isolated from their contents constituted 8(8.0%), while bacteria isolated included E. coli 65 (65%), Shigella 25 (25%) and Salmonella spp. 4(4%). E. coli was the only bacterium isolated from within 8 (8%) the eggs. While no other bacteria were found in eggs contents, the pathogenic bacteria present on the eggs indicated that eggs could be potential sources of outbreaks of food-borne diseases. Regulations and awareness on sanitary quality of eggs are advocated to help safeguard the health of the egg consuming public from egg-borne food infections.

Screening of crows and waterfowls for Salmonella and Listeria monocytogenes infection

Background and Aim: Wild birds can carry a number of potential human and animal pathogens. These birds can intrude into human habitats giving the opportunity to transmission of such infection. Therefore, the current study was designed to investigate the role of crows and waterfowls as vectors of Salmonella and Listeria monocytogenes and to compare cultivation methods with direct polymerase chain reaction (PCR) for the detection of infection. Materials and Methods: A total of 200 fecal dropping samples were collected. Salmonella was cultivated by three step method (Universal Pre-enrichment Broth [UPB], Rappaport-Vassiliadis Broth, and Xylose Lysine Desoxycholate agar). The recovered isolates were characterized by biotyping, serotyping, and PCR detection of enterotoxin (stn) gene. The antibiogram pattern of isolates against a panel of 8 antibiotics was recorded. L. monocytogenes was cultivated on UPB, then on Listeria Oxford Agar and Listeria CHROMagar. The recovered isolates were characterized by biotyping and PCR detection of listeriolysin (hylA) gene. Results: The percentages of Salmonella infection in crows and waterfowls were 10 and 20, respectively. The most frequently recovered serovars were Typhimurium, Potengi, Enteritidis, and Kentucky. Antimicrobial susceptibility analysis of Salmonella isolates showed that the resistance rates for gentamicin were the highest (92%), followed by amoxicillin (88%) and cefixime (60%). Resistance to 8 antibiotics was recorded in 60% (15/25) of Salmonella isolates. The percentages of L. monocytogenes infection in crows and waterfowls were 1.3 and 2, respectively. Direct PCR applied to UPB revealed that 12% and 3% of samples were positive for Salmonella and L. monocytogenes, respectively, and there was no significant difference between direct PCR and cultivation method for the detection of infection. Conclusion: The present findings indicate that wild birds can harbor zoonotic enteric pathogens and this necessitates monitoring the epidemiologic status of these pathogens among wild birds and humans and applying the appropriate intervention measures to prevent the spread of infection.

Efficacy of plant-derived antimicrobials for controlling Salmonella Schwarzengrund on dry pet food

Salmonella enterica is a major human pathogen that is responsible for 23,000 hospitalizations annually in the United States. Contact with contaminated pet food and infected companion animals can transmit salmonellosis to humans. Recent multistate human outbreaks of salmonellosis linked to commercial contaminated dry dog foods underscore the need for controlling the pathogen in pet foods for protecting pet and public health. In this study, the efficacy of five Generally Recognized as Safe (GRAS) status, plant-derived antimicrobials (PDAs), namely trans-cinnamaldehyde (TC), carvacrol (CR), thymol (TY), eugenol (EG), and caprylic acid (CA) applied as a vegetable oil or chitosan based antimicrobial spray on dry pet food for reducing Salmonella Schwarzengrund was investigated. Three hundred gram portions of a commercial dry dog food were inoculated with a two-strain mixture of nalidixic acid (NA) resistant S. Schwarzengrund (~6 log CFU/g), followed by a spray treatment with 0%, 0.5%, 1% or 2% of TC, CR, TY, EG or CA in combination with 5% vegetable oil or 1% chitosan as a carrier. The control and treated dog food samples were stored at 25 °C for 28 days. On days 0, 1, 3, 5, 7, 14, 21, and 28, Salmonella on pet food was enumerated by serial dilution and plating on xylose lysine desoxycholate (XLD) agar. All PDAs at 1% and 2% applied in vegetable oil or chitosan reduced S. Schwarzengrund by at least ~2 log CFU/g on day 3 of storage when compared to control (P < 0.05). No significant reductions in Salmonella were observed on feed sprayed with only vegetable oil or chitosan (P > 0.05). Overall, 2% TC in vegetable oil or chitosan was the most effective treatment, where at least 3 to 3.5 log CFU/g reduction in bacterial populations was observed during storage (P < 0.05). Results suggest that the aforementioned PDAs could potentially be used as an antimicrobial spray to reduce S. Schwarzengrund on dry dog food. However, further studies on the acceptance of PDA-treated dry food by dogs are needed.

Comparison of excision, swabbing and meat fluid sampling techniques on the prevalence and detection of Salmonella from beef in Namibia

Salmonellabacteria cause major challenges in food production and public health because of their ability to cause foodborne disease known as salmonellosis. The microbiological safety of food can be ensured through routine surveillance programs with a view to detect the presence of pathogenic bacteria such as Salmonella. However, the rate of Salmonelladetection in food may be affected by the sampling technique used leaving the product unsafe for human consumption. In order to assess the effectiveness of sampling techniques for Salmonelladetection, atotal of 9508 of beef samples were collected from the local slaughter houses over a period of two years starting from January 2008 to December 2009. Samples used were routine samples collected using three different sampling techniques; excision, swabbing and meat fluid.Samples were pre-enriched in Buffered Peptone Water followed by enrichment in the Rappaport Vissiliadis and Selenite Cystine broths. The isolation of Salmonellawas done on Xylose Lysine Desoxycholate and Brilliant Green agars followed by biochemical confirmation and serotyping according to Kauffman-White scheme. The statistical analysis by Chi square showed that there was a significant difference (p &lt;0.05) on the prevalence of Salmonellabetween the swabbing sampling techniques (2.67 %) with excision (0.50 %) and meat fluid (0.43 %) sampling technique.However, there was no significant difference (p &gt; 0.05) between the excision and meat fluid sampling techniques. The findings suggest that the three samplingtechniques could produce different results when used for sampling beef for Salmonella detection. The swabbing sampling technique showed a higher detection rate of Salmonellaand could be the best choice as compared to other techniques. The significant detection rate of the swabbing sampling technique as compared to other techniques could probably be due to the large surface area employed in this technique as a result of uneven distribution of microorganisms.

Evaluation of modified semisolid Rappaport Vassiliadis medium in comparison with conventional media in the isolation of Salmonella species from different samples

Objectives The goal of this study is to assess the performance of the modified semisolid Rappaport Vassiliadis media (MSRV) for detecting Salmonella spp. in comparison with conventional media especially xylose lysine desoxycholate agar (XLD agar) and Salmonella Shigella (SS) agar. Results The analysis showed that the overall Salmonella prevalence was 10% (18/180). Of the 18 Salmonella-positive samples, 16 (89%) were isolated from patients suffering from gastroenteritis, while one Salmonella strain (5.5%) was detected in the 45 stool samples of food handlers, and one Salmonella strain (5.5%) isolated from the 45 food samples. SS culture results comparable to serotyping resulted in sensitivity, specificity, positive predictive, negative predictive, accuracy values of 83.3, 98.2, 83.3, 98.2, and 96.7%, respectively, while XLD generated 83.3% sensitivity, 97.5% specificity, 79% positive predictive value, 98.1% negative predictive value, 96.1% accuracy. Statistically, the MSRV method resulted in higher values of sensitivity (94.4%), specificity (99.4%), positive predictive value (94.4%), and negative predictive value (99.4%), and accuracy (98.9%) than those obtained by the other two culture methods. Conclusions The current study showed that the overall diagnostic performance of MSRV for the detection of Salmonella spp., including sensitivity, specificity, and accuracy, was significantly (P

Salmonella Presence in Mandibular, Mesenteric, and Subiliac Lymph Nodes Collected from Sheep and Goats in the U.S.

ObjectivesTo survey the presence of Salmonella harbored within lymph nodes of sheep and goats in the United States.Materials and MethodsMandibular, mesenteric and subiliac lymph nodes were collected from 125 sheep and 130 goat carcasses at harvest. Samples were collected at small abattoirs (n = 578; 1 to 30 animals/d) and large (n = 183; 800 to 1,000 animals/d) facilities in California, New Mexico and Texas over a 2-yr period.Lymph nodes were trimmed from fat and fascia, boiled, pulverized and enriched in Tryptone Soy Broth (TSB). Enrichments were subjected to standard immunomagnetic separation (IMS) procedures for Salmonella, selective enrichment in Rappaport-Vassiliadis (RV) broth, and plating onto Xylose Lysine Desoxycholate (XLD) and Brilliant Green Sulfa (BGS) agars. Typical colonies from either medium were latex-agglutinated. A Chi-square test was performed via PROC FREQ on SAS (version 9.4; SAS Inst. Inc., Cary, NC) to compare the frequency of Salmonella by species and lymph node type. Significance was detected at P ≤ 0.05.ResultsIn sheep, Salmonella was detected in 4.0% (5/125) of mandibular, 7.2% (9/125) of mesenteric, and 1.9% (7/125) of subiliac lymph nodes, with no significant difference among lymph node types. In goats, significant differences among lymph node types were detected with Salmonella present in 1.6% (2/128) of mandibular, 3.1% (4/129) of mesenteric and 7.8% (10/129) of subiliac lymph nodes (P = 0.035). Overall Salmonella detection in the combined species was 2.8% in mandibular lymph nodes (n = 253), 5.1% in mesenteric lymph nodes (n = 254) and 6.7% in subiliac lymph nodes (n = 254). Salmonella presence differed significantly by month of collection, with the highest frequency of detection in March (12.36%), and no Salmonella detected in April or November (P < 0.0001). Thirty animals (11 goats, 19 sheep) were found to have 1 or more Salmonella-positive lymph nodes.ConclusionOur data indicate that Salmonella is harbored within the lymph nodes of small ruminants. Further studies are needed to further assess seasonal and geographical effects on the prevalence of this pathogen in sheep and goats, and the potential influence of production practices on Salmonella contamination in ovine and caprine food products.

2008-2014 Yılları Arasında Çevresel Örneklerden İzole Edilen Salmonella Suşlarının Serotip Dağılımı ve Antimikrobiyal Duyarlılıkları

Despite the measures taken and control applications worldwide, Salmonella infections continue to threat the public health. Since these infections also cause significant economical loss, the salmonellas continue to be forefront globally. The determination of Salmonella serotypes and their sources is important for epidemiological point of view. In this study, serotype distribution and antimicrobial resistance of environmental isolates of Salmonella spp. recovered from the poultry farms, that were send for confirmation and serotyping between seven years period, 2008-2014, were evaluated. Strains isolated from environmental samples that were sent to Public Health Institute, Department of Microbiology Reference Laboratory, National Reference Laboratory for Enteric Pathogens, were inoculated onto Salmonella-Shigella and Xylose Lysine Desoxycholate agar and evaluated after 18-24 hours of incubation at 37°C. The identification of the strains was performed by using standard biochemical tests from the suspected colonies. Strains compatible with Salmonella spp. were serotyped using polyvalent and monovalent Salmonella O and H antisera by slide agglutination method. Antibiotic susceptibility tests were performed and evaluated according to CLSI recommendation using Kirby-Bauer disk diffusion method. In our study, a total of 2011 Salmonella strains were evaluated and 15 different serogroups and 75 different serotypes were identified. The most common Salmonella serotypes were S.Infantis (30.6%), followed by S.Enteritidis (21.8%), S.Typhimurium (6.5%), S.Kottbus (5.2%), S.Tennessee (4.3%), S.Mbandaka (4.1%), S.Indiana (3.9%), S.Kentucky (3%), S.Corvallis (2.5%), S.Paratyphi B (1.9%) and S.Hadar (1.7%). Among the isolates, 50.1% (1008/2011) were found susceptible to all of the tested antimicrobials. The rate of isolates that were resistant to only one drug was found to be 15.6%, whereas 30.9% of the strains showed multi-drug resistance (resistant to ≥ 3 antimicrobial drugs). Antimicrobial resistance rates of the Salmonella strains were as follows; nalidixic acid 35.9%, tetracycline 30%, sulfonamides 27.5%, trimethoprim 25.6%, trimethoprim/sulfamethoxazole 25.4%, streptomycin 23.4% and ampicillin 13.5%, respectively. The highest resistance rates for streptomycin (91.4%) ampicillin (88.6%) and tetracycline (88.6%) were observed in S.Hadar strains; for sulfonamide (82.2%) and trimethoprim/sulfamethoxazole (78.2%) in S.Infantis strains, and for nalidixic acid in S.Indiana (97.4%), S.Hadar (91.4%) and S.Infantis (88.8%) strains. In conclusion, the origins, serotypes and antibiotic susceptibility patterns of the strains should be defined for the management of Salmonella infections which are still today a global problem.

Isolation of Bdellovibrio sp. from Wastewater and Their Potential Application in Control of Salmonella paratyphi in Water

ABSTRACTThe problem of the increasing resistance of bacteria to conventional antibiotics gives the bacteria Bdellovibrio a great utility as a potential alternative source of antibiotics. Therefore, the preliminary goal of the present study was isolation and identification of antibiotic-resistant bacteria used as prey organisms for isolated Bdellovibrio sp., by xylose lysine desoxycholate (XLD) agar from different types of water in the Taif area, Saudi Arabia, and also to investigate water quality. Four antibiotic-resistant isolates of Salmonella sp. which were susceptible to Bdellovibrio were identified by morphological, biochemical and 16S rRNA characterization as Salmonella paratyphi. Seventeen strains of Bdellovibrio sp. were isolated from sewage wastewater using isolated S. paratyphi as prey bacteria by a double-layer plate. Only one of them causing a large plaque after 48 h of incubation at 37°C was designated Bdellovibrio AOA12. The shape of Bdellovibrio was confirmed by morphological characterization and electron microscopy. Bdellovibrio could lyse four antibiotic-resistant Gram-negative bacterial strains of Salmonella paratyphi but could not lyse Gram-positive bacteria such as Staphylococcus aureus and Bacillus cereus. The kinetic lysis of the Bdellovibrio as predator to four isolates of antibiotic-resistant Salmonella paratyphi as prey organisms was demonstrated. The results suggest that it may be possible to utilize Bdellovibrio to control antibiotic-resistant S. paratyphi in water.

Prevalence and Characterization of Salmonella Isolated from Beef in Namibia

Aim: The purpose of this research was to determine the prevalence of Salmonella in raw beef produced from selected commercial abbatoirs in Namibia. Methodology: A total of 9508 of beef samples from three different types of samples; meat cuts, carcass swabs and meat fluid were collected from the three local abattoirs over a period of two years starting from January 2008 to December 2009. Pre - enrichment for isolati on of Salmonella was done in Buffered peptone water followed by enrichment in the Rappaport - Vassiliadis and selenite cystine broth. The isolation of Salmonella was done on Xylose Lysine Desoxycholate and Brilliant Green agar followed by biochemical confirm ation and serotyping according to Kauffman White scheme. Results: The overall prevalence of Salmonella was 0.85 % for beef samples derived from meat cuts, meat fluid and carcass swabs. The prevalence of Salmonella in carcass swabs (2.67 %) was significantly different ( P = 0.0 5) from that of meat cuts (0.50 % ) and meat fluid (0.43 %). No significant difference ( P = 0.05) on the prevalence of Salmonella existed between the meat cuts and meat fluid. A total of 34 different types of Salmonella serovars were identified with S. Chester being the most frequently isolated serovars (n = 12), followed by S. Reading and S . Bredeney (n = 6) and S. Typhimurium (n = 5). Conclusions: The prevalence of Salmonella in raw beef found in this survey was lower than those observed in Sub Sahara Africa with S. Chester being the most prevalent serovar. Original Research Article

Enterobacterial colonization in captive red-eared sliders (Trachemys scripta elegans).

The handling of turtles and other reptiles can be associated with risk of pathogenic enterobacteria transmission, mainly Salmonella spp. The aim of this study was to identify the enterobacteria in cloacal swabs of 39 red-eared sliders (Trachemys scripta elegans). Cloacal swabs from 39 captive individuals were analyzed. After sample enrichment in brain-heart infusion broth and 1% peptone water, bacterial isolation was performed through cultivation in blood, MacConkey and xylose lysine desoxycholate agar. Bacterial identification was achieved through conventional tests and automated turbidity analysis. The results indicated the growth of Kluyvera ascorbata (38/39), Leclercia adecarboxylata (37/39), Raoultella planticola (30/39), Citrobacter freundii (20/39), Proteus spp. (15/39), and Escherichia coli (5/39). Salmonella spp. were not detected. The intestinal enterobacteria identified inthis study differed from that reported in the literature for other reptiles.

Shigella isolates from the global enteric multicenter study inform vaccine development.

Shigella, a major diarrheal disease pathogen worldwide, is the target of vaccine development. The Global Enteric Multicenter Study (GEMS) investigated burden and etiology of moderate-to-severe diarrheal disease in children aged <60 months and matched controls without diarrhea during 3 years at 4 sites in Africa and 3 in Asia. Shigella was 1 of the 4 most common pathogens across sites and age strata. GEMS Shigella serotypes are reviewed to guide vaccine development. Subjects' stool specimens/rectal swabs were transported to site laboratories in transport media and plated onto xylose lysine desoxycholate and MacConkey agar. Suspect Shigella colonies were identified by biochemical tests and agglutination with antisera. Shigella isolates were shipped to the GEMS Reference Laboratory (Baltimore, MD) for confirmation and serotyping of S. flexneri; one-third of isolates were sent to the Centers for Disease Control and Prevention for quality control. Shigella dysenteriae and S. boydii accounted for 5.0% and 5.4%, respectively, of 1130 Shigella case isolates; S. flexneri comprised 65.9% and S. sonnei 23.7%. Five serotypes/subserotypes comprised 89.4% of S. flexneri, including S. flexneri 2a, S. flexneri 6, S. flexneri 3a, S. flexneri 2b, and S. flexneri 1b. A broad-spectrum Shigella vaccine must protect against S. sonnei and 15 S. flexneri serotypes/subserotypes. A quadrivalent vaccine with O antigens from S. sonnei, S. flexneri 2a, S. flexneri 3a, and S. flexneri 6 can provide broad direct coverage against these most common serotypes and indirect coverage against all but 1 (rare) remaining subserotype through shared S. flexneri group antigens.

Is it safe to eat raw seafood? Prevalence of Salmonella in some seafood products sold in Alexandria markets

Salmonella is a significant microbial hazard in seafood. Salmonella-contaminated seafood usually looks and smells normal; it is therefore essential that every effort is made toward the rapid detection of Salmonella as an important criterion in quality control of seafood. This study aims to determine the percentage of Salmonella in some Egyptian seafood sold in Alexandria markets and to study the validity of Chromagar Salmonella Plus (CASP) agar versus xylose lysine desoxycholate and Salmonella-Shigella agar for the isolation and identification of Salmonella in seafood. Two hundred and twenty-five samples of three seafood types, shrimp, gandofli, and river mussel (om-elkhloul) were studied. Samples were selectively enriched in Rappaport-Vassiliadis and tetrathionate broth, and then plated onto the aforementioned plating media for the detection of Salmonella. In total, Salmonella was detected in 9.8% of the samples. The sensitivity and specificity of the media used varied according to the media and enrichment broth combinations used. The CASP and Rappaport-Vassiliadis combination yielded the best sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 95.45, 100, 100, 99.5, and 99.5%, respectively. CASP was more accurate than xylose lysine desoxycholate and Salmonella-Shigella in the detection of Salmonella from seafood samples. We recommend that CASP medium should be tested against more Salmonella-positive samples before it is used as a screening plating medium for Salmonella in seafood.

Identification and characterization of Salmonella species in whole egg purchased from local markets in Addis Ababa, Ethiopia

Currently, salmonellosis is one of the major food borne pathogen both in developing and developed countries. Humans encountered this problem by consuming raw or undercooked food especially of poultry and egg products. The objective of the study was to identify and characterize Salmonella species in trans-ovarian contaminated eggs purchased from local markets in Addis Ababa. The study was conducted by using a standard laboratory diagnostic procedure. Isolation of Salmonella species from eggs was done both in solid and liquid media, and among three hundred eighty four (384) clean and non-cracked eggs examined, twenty eggs (5.21%) were positive forSalmonella enteritidis using selinite broth and Rappaport vassilidies broth as liquid media and xylose lysine desoxycholate (XLD) agar, MacConkey, Salmonella Shigellaagar as solid media. S. enteritidis positive eggs (n = 20) when subjected to biochemical test using lysine iron agar (LIA) identified eighteen (4.69%) positive and two (2) negative samples. In this research, some commercial eggs yielded a number of S. enteritidis. This can be attributed to different causes but the most important one is transovarian transmission which implicate the possibility of poor animal health in layer farms. Storage time/temperature play the most significant role for its multiplication. Key words: Egg, Salmonella enteritidis, Addis Ababa.

First Report on Isolation of Salmonella Enteritidis from Eggs at Grocery Stores in Korea

Salmonella Enteritidis is responsible for causing foodborne diseases upon consumption of egg products. While cases of S. Enteritidis isolation from eggs have been reported in other countries, no such cases have previously been reported in Korea. In this study, we report the first isolation and identification of S. Enteritidis from domestically distributed eggs in Korea. Eggs were collected from eight countrywide grocery stores during different seasons between 2011 and 2012. Egg contents and washing solution of egg shells were incubated in buffered peptone water, and the enriched broth was further enriched in tetrathionate broth and Rappaport-Vassiliadis. The secondary enriched broth was streaked on xylose lysine desoxycholate agar. The suspected colonies were confirmed to S. Enteritidis by a biochemical test, serotyping, and PCR test. Genetic relatedness among the isolates was analyzed using Diversilab Salmonella kit. Three strains of S. Enteritidis were isolated from egg contents and egg shells collected from grocery stores of the Eumseong-city in the fall of 2011. All three stains showed resistance to chloramphenicol, streptomycin, nalidixic acid, and ampicillin by the disk diffusion method. In addition, the isolates showed more than 99% DNA homology, indicating that they were presumably identical strains. Therefore, there is a requirement to monitor and control against S. Enteritidis from eggs in Korea.

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A cross sectional study was conducted between November, 2011 and April, 2012 to determine the prevalence and&nbsp;risk factors associated&nbsp;with&nbsp;Salmonella&nbsp;infection among chicken flocks in Jimma town, Ethiopia. Management system, sex, season, age and breed of the chicken flocks examined in the study were considered as risk factors and evaluated whether they are associated with&nbsp;Salmonella&nbsp;infection or not. A bacteriological examination was carried out on 384 faecal samples originated from 232 exotic chicken flocks which were kept indoors and 152 local chicken flocks which were free ranging. The faecal samples were enriched with peptone water for 24 h and then seeded on the selective enrichment media, Rappaport Vassiliadis Soy Broth and incubated at 37&deg;C for 24 h. Following selective enrichment,&nbsp;0.1 ml of the pre enriched broth of the various dilutions were streaked aseptically&nbsp;into Xylose Lysine Desoxycholate (XLD) agar plates and incubated at 37&deg;C for 24 h. Presumptive identification of&nbsp;Salmonella&nbsp;was done based on morphology and colour of the colonies on the culture media. Final identification and assignment of&nbsp;Salmonella&nbsp;was conducted by employing biochemical tests such&nbsp;indole production,&nbsp;citrate utilization and urease tests.&nbsp;The identification result proved the overall prevalence of&nbsp;Salmonella&nbsp;to be 41.9%. The prevalence of&nbsp;Salmonella&nbsp;infection were found to be higher in indoor chickens (42.7%) than chickens that were kept as free ranging (40.8%) but there was no statistically significant difference (p&gt;0.05) on the prevalence ofSalmonella&nbsp;infection in chicken flocks between management systems. The prevalence ofSalmonella&nbsp;in female chicken flocks (43.0%) was higher than in male chicken flocks (39.0%) and there was no statistical significant difference (P&gt;0.05) on the prevalence ofSalmonella&nbsp;between sexes. The highest prevalence of&nbsp;Salmonella&nbsp;was recorded during spring (47.7%) followed by autumn (39.7%) and the lowest prevalence of&nbsp;Salmonellainfection among chicken flocks was seen during winter (36.8%). Statistical analysis of the data showed that there was no statistical significant difference (P&gt;0.05) on the prevalence of&nbsp;Salmonella&nbsp;in chicken flocks among seasons. Layers and cocks were proved to be highly infected with&nbsp;Salmonella&nbsp;(46.2%) followed by broilers (41.3%). The lowest prevalence of&nbsp;Salmonella&nbsp;infection was seen in chickens (40.8%). There was no statistical significant difference (P&gt;0.05) on the prevalence of&nbsp;Salmonella&nbsp;in chicken flocks among ages. The prevalence of&nbsp;Salmonella&nbsp;was proved to be higher in exotic breed chicken flocks (42.7%) than chicken flocks which were kept as free ranging (40.8%). Analysis of the data showed there was no statistical significant difference (P&gt;0.05) on the prevalence of&nbsp;Salmonella&nbsp;among chicken flocks between breeds. The prevalence of&nbsp;Salmonellaamong chicken flocks in Jimma town, Ethiopia, was proved to be very high. Hence, strengthening the knowledge, attitude and practice of chicken flock owners must be inaugurated in the area to mitigate the economic losses which could arise due toSalmonella&nbsp;infection in chicken flocks. &nbsp; Key words:&nbsp;Salmonella, prevalence, chicken flocks, Jimma town, Ethiopia.

Effect of the Enrichment Medium on the Detection and Diversity ofSalmonellafrom Porcine Duodenal Content

This study assesses the effect of the enrichment medium used on the isolation of Salmonella from the duodenal content of naturally infected slaughter pigs. At six slaughterhouses, the duodenum was collected from 458 randomly chosen pigs and examined in the laboratory. Three semi-solid enrichment media (modified semi-solid Rappaport-Vassiliadis medium [MSRV], diagnostic semi-solid Salmonella medium [DIASALM], and Simple Method Salmonella [SMS] agar) and three enrichment broths (Rappaport-Vassiliadis, Rappaport Vassiliadis broth with Soya [RVS], and Muller Kauffmann Tetrathionate novobiocin broth [MKTTn]) were evaluated. If a migration zone was present on the semi-solid media, a loopful was taken both near the inoculation drop and at the edge of the migration zone and streaked on a Xylose Lysine Desoxycholate (XLD) agar plate. Each enrichment broth was streaked on XLD, and three presumptive colonies were further examined. Detection rate was calculated, and isolates were, after serotyping, genotyped by performing pulsed-field gel electrophoresis (PFGE). The overall frequency of Salmonella isolated in at least one of the six different media was 15.5% (71/458). No significant differences in relative sensitivity were obtained within semi-solid media and within liquid media. Semi-solid media showed a significant higher relative sensitivity than the one obtained with liquid media. A relative sensitivity higher than 83.1%, namely of 94.4%, could only be obtained by combining three different enrichment media (MSRV or DIASALM+RVS+MKTTn). In 13.4% of the positive pigs, more than one serotype was found within the duodenum of one pig. In 12.9% of the duodenal contents, different genotypes were found within the same serotype. Differences in serotypes and genotypes were found predominantly within the same enrichment medium. In conclusion, to obtain the highest Salmonella detection rate in naturally contaminated pig samples, MSRV should be used as enrichment medium. However, to obtain a realistic picture of the sero- and genotypes present, different samples per enrichment medium and different enrichment media should be tested.

Development of an Improved Selective and Differential Medium for Isolation of Salmonella spp

We describe an improved selective, differential, and cost-effective medium, XA medium, which contains d-arabinose, to facilitate the selective isolation of Salmonella spp. The sensitivity and the specificity of XA medium were compared to those of xylose lysine desoxycholate agar (XLD) using stock cultures and naturally contaminated food samples. XA medium and XLD were evaluated with a total of 82 Salmonella and 69 non-Salmonella stock cultures. Of 82 strains of Salmonella spp. tested, 76 produced a characteristic black colony on XA medium and XLD. The remaining 6 strains belonged to Salmonella enterica serovars Berta (n = 1), Paratyphi A (n = 1), Gallinarum (n = 2), and Pullorum (n = 2). The sensitivities of XA medium and XLD were identical (92.7%). Citrobacter freundii (n = 21) and Proteus mirabilis (n = 21) stock cultures produced black colonies on XLD, whereas only 4 strains of P. mirabilis appeared as black colonies on XA medium. In the second phase of the study, a total of 180 food samples were cultured onto XA medium and XLD after selective enrichment. The sensitivities of XA medium and XLD were equal (100%), and a total of 6 Salmonella strains were isolated from the 180 food samples. The specificity of XA medium (92.0%) was superior to that of XLD (73.0%), with a total of 14 and 47 false-positive results found on XA medium and XLD, respectively. On the basis of its good specificity, XA medium is useful for the isolation of Salmonella spp. from food samples.