Presence of ESBL/AmpC -Producing Escherichia coli in the Broiler Production Pyramid: A Descriptive Study

Broilers and broiler meat products are highly contaminated with extended spectrum beta-lactamase (ESBL) or plasmid-mediated AmpC beta-lactamase producing Escherichia coli and are considered to be a source for human infections. Both horizontal and vertical transmission might play a role in the presence of these strains in broilers. As not much is known about the presence of these strains in the whole production pyramid, the epidemiology of ESBL/AmpC-producing E. coli in the Dutch broiler production pyramid was examined. Cloacal swabs of Grandparent stock (GPS) birds (one−/two-days (breed A and B), 18 and 31 weeks old (breed A)), one-day old Parent stock birds (breed A and B) and broiler chickens of increasing age (breed A) were selectively cultured to detect ESBL/AmpC-producing isolates. ESBL/AmpC-producing isolates were found at all levels in the broiler production pyramid in both broiler breeds examined. Prevalence was already relatively high at the top of the broiler production pyramid. At broiler farms ESBL/AmpC producing E. coli were still present in the environment of the poultry house after cleaning and disinfection. Feed samples taken in the poultry house also became contaminated with ESBL/AmpC producing E. coli after one or more production weeks. The prevalence of ESBL/AmpC-positive birds at broiler farms increased within the first week from 0–24% to 96–100% independent of the use of antibiotics and stayed 100% until slaughter. In GPS breed A, prevalence at 2 days, 18 weeks and 31 weeks stayed below 50% except when beta-lactam antibiotics were administered. In that case prevalence increased to 100%. Interventions minimizing ESBL/AmpC contamination in broilers should focus on preventing horizontal and vertical spread, especially in relation to broiler production farms.     

Sequence analysis of a bacteriocinogenic plasmid of Clostridium butyricum and expression of the bacteriocin gene in Escherichia coli

A small cryptic plasmid, namely, pCBM588, was obtained from Clostridium butyricum MIYAIRI 588 (CBM588) — a bacterium used in probiotics. The complete sequence of pCBM588 was determined. The size of pCBM588 was 8060 bp and the G + C content was 24.3%. Nine open reading frames (ORFs) were predicted, and ORF3 showed significant homologies with a structural bacteriocin gene of Clostridium tyrobutyricum. The putative bacteriocin gene was inserted into the pET21d expression vector in frame; it was expressed as a His-tagged recombinant protein in Escherichia coli BL21 (DE3). A total of 10240 AU of the recombinant bacteriocin were purified from 100 ml of E. coli culture. The bacteriocin was cleaved into 2 portions, and the small C-terminal polypeptide consisting of 83 amino acids possessed bactericidal activity. These results demonstrated that the ORF3 of pCBM588 encoded a bacteriocin, which is identical or very similar to the previously reported butyricin 7423.     

Application of Bacteriophages To Control Intestinal Escherichia coli O157:H7 Levels in Ruminants

A previously characterized O157-specific lytic bacteriophage KH1 and a newly isolated phage designated SH1 were tested, alone or in combination, for reducing intestinal Escherichia coli O157:H7 in animals. Oral treatment with phage KH1 did not reduce the intestinal E. coli O157:H7 in sheep. Phage SH1 formed clear and relatively larger plaques on lawns of all 12 E. coli O157:H7 isolates tested and had a broader host range than phage KH1, lysing O55:H6 and 18 of 120 non-O157 E. coli isolates tested. In vitro, mucin or bovine mucus did not inhibit bacterial lysis by phage SH1 or KH1. A phage treatment protocol was optimized using a mouse model of E. coli O157:H7 intestinal carriage. Oral treatment with SH1 or a mixture of SH1 and KH1 at phage/bacterium ratios ≥10² terminated the presence of fecal E. coli O157:H7 within 2 to 6 days after phage treatment. Untreated control mice remained culture positive for >10 days. To optimize bacterial carriage and phage delivery in cattle, E. coli O157:H7 was applied rectally to Holstein steers 7 days before the administration of 10¹⁰ PFU SH1 and KH1. Phages were applied directly to the rectoanal junction mucosa at phage/bacterium ratios calculated to be ≥10². In addition, phages were maintained at 10⁶ PFU/ml in the drinking water of the phage treatment group. This phage therapy reduced the average number of E. coli O157:H7 CFU among phage-treated steers compared to control steers (P < 0.05); however, it did not eliminate the bacteria from the majority of steers.     

Recent approaches for control of E. coli and respiratory complex in Middle East

This study was conducted on 100 one-day-old broiler chicks to evaluate the effect of Poulvac E. coli vaccine in reduction of clinical signs and complications after concurrent infectious bronchitis virus (variant 02) and virulent E. coli O78 challenges. The birds were evaluated for clinical signs, mortality for 7?days post-infection, PM lesion score, average body weight and serological evaluation. Re-isolation and RT-PCR for the challenging infectious bronchitis virus (IBV) variant 02 were conducted thereafter. The results showed that the Poulvac E. coli at one-day old chicks in the presence of co-infection with virulent E. coli and IBV variant 02 provides better body weight gain at 35?days than the other groups. The challenge with IBV variant 02 alone in non-vaccinated birds doesn’t give any mortality; this indicated that the severity of IBV variant 02 increased by the presence of co-infection with Avian Pathogenic E. coli (APEc). The mortality percentage associated with both E. coli and IBV variant 02 infections in the none vaccinated group by Poulvac E. coli was 25% while this percentage was 10% of the vaccinated group. The Poulvac E. coli is not negatively affecting the immune response against different concurrent viral vaccines like Infectious bursal disease (IBD), and moreover, it improves the immune response against some others like Newcastle disease virus (NDV), Avian Influenza (AI) H5 and IBV.     

Biosafety evaluation of bacteriophages for treatment of diarrhea due to intestinal pathogen Escherichia coli 3-2 infection of chickens

Intestinal Escherichia coli caused diarrhea in chicken makes serious damage directly to the chicken culture industry. Bacteriophage therapy is able to control the diarrhea in chickens effectively. In this study, the biosafety of bacteriophages was evaluated for treating intestinal pathogenic E. coli, which induced diarrhea in chickens. Ten bacteriophages were isolated from feces of chickens with diarrhea using the ill-chicken intestinal pathogenic E. coli 3-2 as target organism. Three bacteriophages propagated on E. coli 3-2 with relative big and clear plaques were selected and used together for toxicity experiment and evaluating the effect of therapy on chicken weight gain. In 3 weeks of trial, no mice given with or without mixed bacteriophages died, and the weight of mice of the experimental group did not show significant difference to the control group after 3 weeks infection. Besides remarkable decreasing the death rate of chickens with diarrhea, treatment of mixed bacteriophages also promoted the weight gain and saved the diet consumption as the utilize rate of diet increased 11% compared with the control group. These observations indicated that a mixture of three bacteriophages would be biosafe for rapid and effective preventing pathogenic E. coli infections.     

Antibacterial effect of honey on the in vitro and in vivo growth of Escherichia coli

The study investigated the antibacterial effect of honey against pathogenic Escherichia coli. Honey showed inhibitory activity against the growth of E. coli (ATCC 25922) in agar plate assay. In liquid culture (48 h, 37 °C) the growth rate of bacterial cells decreased in the presence of honey (9.6 × 10⁵ c.f.u./ml) compared with sucrose (2.87 × 10⁸ c.f.u./ml). Rats fed with honey and orally inoculated with E. coli excreted significantly (P < 0.05) less bacterial cells in faeces compared to controls. Animals acclimatized to feeding of honey prior to E. coli inoculation showed a significant decrease in excreted bacterial load compared with the group provided with honey after bacterial inoculation. Consumption of honey also enhanced the concentration of short chain fatty acids in the intestine of rats (83 mM) compared with the control group (44.5 mM). The results show that honey possessed significant antibacterial activity against E. coli under in vitro and in vivo conditions, and indicate the potential benefit of consumption of honey regularly on the microbiological constitution of animals feeding on it.     

Benefit of Dietary Supplementation with Bacillus subtilis BYS2 on Growth Performance,Immune Response,and Disease Resistance of Broilers

A strain of Bacillus subtilis (B. subtilis) BYS2 was previously isolated from Mount Tai, which is located in Tai’an City in the Shandong Province of China. The strain was then stored in the Environmental Microbiology Laboratory at Shandong Agricultural University. To evaluate the effect of the bacterium preparation in broiler production, we fed the bacterium (10⁶ CFU/g) to 1-day-old broilers and continued this feeding for 6 weeks to analyze its effect on growth and immune performance. We found that the average weight of the bacterium-fed group increased by 17.19% at weeks 5 compared to the control group (P < 0.05). The height of the villi in the duodenum and jejunum and the ratio of villi to crypt were significantly increased in the bacterium-fed group at weeks 5 (P < 0.05). Also, the IgG in the serum of broilers in the experimental group increased by 31.60% (P < 0.05) and IgM 30.52% (P < 0.05) compared with those in the control group. The expressions of the major pattern recognition receptors (PRRs), antiviral proteins, pro-inflammatory cytokines, and β-defensins were significantly higher than those in the control group (P < 0.05). Meanwhile, the bursa immune organ indices of broilers in the experimental group were significantly higher than those in the control group (P < 0.05). Also, after 5 weeks of continuous feeding, when infected with Escherichia coli (E. coli) O1K1 and Newcastle disease virus (NDV) F48E8, the content of bacteria and virus in tissues and organs of the experimental group decreased significantly, and the survival rate of infected chickens increased by 31.1% and 17.7%, respectively (P < 0.05). These results show that the anti-infective B. subtilis BYS2 could, to some extent, replace antibiotics to promote growth, improve innate immunity, and enhance disease resistance in broilers.

     

Isolation of Lactobacillus salivarius 1077 (NRRL B-50053) and characterization of its bacteriocin, including the antimicrobial activity spectrum

Lactobacillus salivarius 1077 (NRRL B-50053) was isolated from poultry intestinal materials, and in vitro anti-Campylobacter jejuni activity was demonstrated. The isolate was then used for bacteriocin production and its enrichment. The protein content of the cell-free supernatant from the spent medium was precipitated by ammonium sulfate and dialyzed to produce the crude antimicrobial preparation. A typical bacteriocin-like response of sensitivity to proteolytic enzymes and resistance to lysozyme, lipase, and 100°C was observed with this preparation. The polypeptide was further purified by gel filtration, ion-exchange, and hydrophobic-interaction chromatography. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), Edman degradation, and isoelectrofocusing were used to characterize its 3,454-Da molecular mass, the amino acid sequence of its 37 residue components, and the isoelectric point of pI 9.1 of the bacteriocin. Bacteriocin L-1077 contained the class IIa bacteriocin signature N-terminal sequence YGNGV. MICs of bacteriocin L-1077 against 33 bacterial isolates (both Gram negative and Gram positive) ranged from 0.09 to 1.5 μg/ml. Subsequently, the therapeutic benefit of bacteriocin L-1077 was demonstrated in market-age (40- to 43-day-old) broiler chickens colonized with both C. jejuni and Salmonella enterica serovar Enteritidis. Compared with untreated control birds, both C. jejuni and S. Enteritidis counts in colonized ceca were diminished by >4 log(10) and S. Enteritidis counts in both the liver and the spleen of treated birds were reduced by 6 to 8 log(10)/g compared with those in the nontreated control birds. Bacteriocin L-1077 appears to hold promise in controlling C. jejuni/S. Enteritidis among commercial broiler chickens.     

Bacteriophage therapy as an alternative biocontrol against emerging multidrug resistant E. coli in broilers

Avian pathogenic Escherichia coli (APEC) is considered a severe issue to both poultry business and health of the general public. In that context, 50 samples from 250 diseased broiler chickens in 10 chicken farms were employed to Escherichia coli isolation. Microbiological techniques were employed to detect isolates of E. coli from 250 diseased broiler chickens which were examined by antimicrobial susceptibility profiles against 11 antimicrobial agents using disc diffusion technique as well as their biofilm forming capacity were detected. In addition to, study the isolation and purification of phages based on spot technique to verify that lytic phages are present in E. coli isolates and plaque assay for titration of bacteriophages. In the present research, we also looked at the ability of bacteriophages to inhibit and dissolve previously formed biofilms by E. coli O78 isolate. Moreover, experimental testing of E. coli O78 bacteriophages for colibacillosis prevention and control in one day old broiler chicks were done. The obtained results showed that twenty-six E. coli isolates out of 50 examined samples were isolated (10.4%). The most prevalent serotypes were O78, O121:H7, O146:H2, O124, O113:H4, O112:H2, O1:H7, O55:H7, O2:H6, O91:H21, O26:H11. Antibiogram results demonstrated the resistance of E. coli isolates with high percentage 100% were against, Ampicillin, Amoxicillin and Tetracycline. Biofilm quantification analysis showed that 24/26 (92.3%) isolates were considered biofilm producer isolates. The characterization and the lytic activity of bacteriophage were performed based on Transmission electron microscopy and showed the greatest lytic activity against the evaluated host strains with effective activity at concentration of 10⁷ at 24 h and strong significant reduction of the established E. coli O 78 biofilm within 12 h. The result of experimental infection showed that the performance indicators of phage in treated and challenged group showed high significant increase in body weight, weight gain and improved FCR than infected –antibiotic treated and infected bacteriophage and antibiotic treated. Total viable cell counts of E. coli in the lungs of birds revealed that there is highly significant difference between the six groups count results. We concluded that phage therapy found to be an attractive option to prevent and control multidrug resistant colibacillosis in broilers.     

The effect of Candida famata and Lactobacillus plantarum on the number of coliforms and the antibiotic resistance and virulence of Escherichia coli in the gut of broilers

This study was undertaken to determine the effect of a yeast (Candida famata) and a bacterium (Lactobacillus plantarum), administered alone or in combination in the drinking water, on the population of yeast, Lactobacillus sp. and coliforms, and the prevalence of antimicrobial resistance (AMR) and virulence genes in Escherichia coli (E. coli) isolated from digesta samples taken throughout the life of broiler chickens. Male (Ross 308) day-old chicks (220) were used. C. famata (isolated from a chicken) and L. plantarum (isolated from a pig) were administered via the drinking water. Water was provided either untreated or with C. famata (CF; 10⁸/ml), L. plantarum (LP; 10⁵–10⁸/ml), or a combination of CF and LP (10⁶–10⁸/ml) in water hoppers on 2 days each week for 35 days. Administering probiotics did not affect the growth performance in broiler chickens. No significant interactions were observed between main effects, and neither CF nor LP had any effect on the population size of Lactobacillus sp. or coliforms. The administration of C. famata increased the population density of yeasts in the small intestine at these ages. The population density of coliforms, Lactobacillus sp. and yeast decreased with age (P < 0.001). There was no significant effect of probiotics on the prevalence of phenotypic AMR and virulence genes in these studies. The prevalence of E. coli that was resistant to ampicillin and tetracycline, as well as carrying ≥3 virulence-associated genes, was greatest at the end of the starter phase (around 8 days old), before declining through the grower and finisher phases. There was only limited evidence that administering either CF or LP affected either the AMR or the virulence of E. coli in the bird. However, tetracycline resistance in E. coli was associated (P < 0.001, P < 0.01, P < 0.05, and P < 0.05) with the carriage of the iron uptake systems of E. coli D, iron-repressible protein, increased serum survival and temperature-sensitive haemagglutinin genes respectively, suggesting that the accumulation of iron and the genetic element conferring tetracycline resistance may be intertwined.     

Antibiotic resistance in commensal intestinal microflora

The susceptibility toward antibiotics was determined by disc and MIC methods in Lactobacillus and, for comparison, in Escherichia coli strains isolated from cloacal swabs of broiler chickens derived from various farms in Slovakia. The occurrence of acquired tetracycline resistance in E. coli and lactobacilli isolated from the same sample was similar. The presence of tet(M), tet(S), tet(L) and ermB genes was demonstrated in lactobacilli while the tet(M) gene was not detected in E. coli.     

Plant extract supplementation as a strategy for substituting dietary antibiotics in broiler chickens exposed to low ambient temperature

ABSTRACT

The present study was conducted to investigate the effects of two plant extracts as alternatives to dietary antibiotics in broiler chickens exposed to low ambient temperature. A total of 300 one-day-old male broiler chickens were randomly assigned to four dietary treatments (5 replicate pens; 15 broiler chickens each) which consisted of starter (d 0 to 10), and grower (d 10 to 28) diets. Dietary treatments included a basal diet (negative control, NC) and three similar diets that were either supplemented with 200 mg/kg of Prosopis farcta extract (PFE), Rhus coriaria L. extract (RCE) or an antibiotic premix containing oxytetracycline (positive control, PC). In order to simulate low ambient temperature, room temperature was maintained at 32°C during the first 3 d of the trial and afterwards, the temperature was gradually reduced by approximately 1.5°C each day to 14°C on d 21. PFE and PC treatments exerted a significant effect on body weight gain at d 28. Diet PFE was effective in reducing mortality when compared with diet NC (p < 0.05). Furthermore, diet PFE caused increases in ileal digestibility of gross energy, dry matter and organic matter when compared with diet NC (p < 0.05). Diets PFE and PC decreased coliforms, total aerobic bacteria and total anaerobic bacteria loads in the caeca when compared with diet NC (p < 0.05). Moreover, the addition of PFE to the diet improved villous height in all small intestinal segments as well as villous height:crypt depth ratio in the duodenum when compared with diet NC (p < 0.05). The results indicated that PFE is not only a valid alternative to oxytetracycline under cold stress conditions, with no antibiotic resistance, but also has the potential to increase the resistance of broiler chickens against ascites syndrome. Moreover, the addition of RCE at the concentration of 200 mg/kg to the diet was not sufficient to improve the performance of broiler chickens (similar to diet PC) but maybe more effective at higher concentrations.     

Seasonal variations in the immune system of the tench,Tinca tinca (Cyprinidae): proliferative response of lymphocytes induced by mitogens

The proliferation of tench lymphocytes induced by mitogens was studied during the four seasons of the year. Fish were maintained under natural conditions of photoperiod and temperature (mean ± SD: 12±2°C in winter, 22±3°C in spring, 30±3°C in summer and 21±3°C in autumn). Cultures were performed in vitro at 22°C in all seasons and the results were compared. Subsequently, in seasons with extreme water temperatures, cultures in vitro were performed at the same temperature as that of the water (12°C in winter and 30°C in summer) and the results were compared seasonally at the seasonal temperature, i.e. at 22°C in spring, 30°C in summer, 22°C in autumn and 12°C in winter. Phytohemagglutinin, concanavalin A, lipolisaccharide from E. coli and pokeweed mitogen were used as mitogens. Studies performed at 22°C as assay temperature in all seasons showed profound seasonal changes: while in spring, summer and autumn the mitogenic response of lymphocytes to phytohemagglutinin, concanavalin A, lipolisaccharide from E. coli and pokeweed mitogen was very low, during winter the results obtained were significantly higher. However, when the assays were performed at the corresponding seasonal temperature the differences were not as pronounced between the different seasons, and the mitogenic responses of lymphocytes were found to be the lowest during the winter and the highest during the summer with all mitogens used. This fact suggests that immunosuppression occurs in winter and an immunostimulation occurs in summer. However, the higher response found in winter when assaying at 22°C suggests that this property of lymphocytes needs an assay temperature higher than the in vivo temperature in order to observe accurate mitogenic responses.Abbreviations Con A concanavalin A - cpm counts per minute - LPS E. coli lipolisaccharide - MS222 tricainemethane sulphonate - PBS phosphate-buffered saline - PHA phytohemagglutinin - PWM pokeweed mitogen - SI stimulation index     

Genotype Analysis of Escherichia coli Strains Isolated from Children and Chickens Living in Close Contact

Escherichia coli isolates from rectal swabs from 62 chickens and stools from 42 children living in close contact with chickens on the same farms in Kiambu district, Kenya, were compared for their genetic relatedness. Antibiotic susceptibility profiles broadly categorized isolates from the children and from the chickens into two separate clusters: the majority (144; 85.5%) of the E. coli isolates from children were multidrug resistant, while the majority (216; 87.1%) of the E. coli isolates from chickens were either fully susceptible or resistant only to tetracycline. Sixty- and 100- to 110-MDA plasmids were found to encode the transferable resistance to co-trimoxazole and tetracycline. HindIII restriction endonuclease digestion of the 60- and 100- to 110-MDA plasmids produced four distinct patterns for isolates from children and three distinct patterns for isolates from chickens. XbaI digestion of genomic DNA followed by pulsed-field gel electrophoresis (PFGE) analysis produced 14 distinct clusters. There were six distinct PFGE clusters among the isolates from children, while among the isolates from chickens there were seven distinct clusters. Only one PFGE cluster contained isolates from both children and chickens, with the isolates displaying an approximately 60% coefficient of similarity. This study showed that although several different genotypes of E. coli were isolated from children and chickens from the same farms, the E. coli strains from these two sources were distinct.     

Studies on Bacillus licheniformis endo-\-1,3-1,4-d-glucanase: characterization and kinetic analysis

Summary A new purification procedure for endo-\-1,3-1,4-d-glucanase from Bacillus licheniformis is described. The secreted enzyme was purified both from B. licheniformis and from recombinant Escherichia coli harbouring the cloned gene by ion exchange chromatography on a CM-Sepharose matrix at pH 5.6. The mature enzyme was resistant to proteolysis by trypsin and chymotrypsin but it was slowly digested by protease V8. It showed a continuous trimming where no large-limit polypeptides were noticeable thus supporting a monodomain structure. Former appearing peptides have been assigned theoretically according to the protein sequence and predictive methods of accessible areas. Kinetic parameters for the hydrolysis of barley \-glucan and lichenan by measuring the net release of reducing sugars at the optimum pH (7.02) and temperature (55° C) are k _cat=3500 ±800 s^–1 (turnover number) and K _m=1.45±0.21 mg/ml for barley \-glucan and k _cat=3000±750 s^–1 and K _m=1.98±0.40 mg/ml for lichenan. Correspondence to: E. Querol     

Characteristics of five bacteriophages of yellow-pigmented enterobacteria

Four bacteriophages (C2, C2F, E3, and E16P) belonging to morphological group C3 and one belonging to morphological group A3 (E16B) were purified by deuterium oxide gradient centrifugation and cesium chloride gradient centrifugation. Morphological group C3 phages had a densityd=1.534–1.541 and group A3 phage (E16B) had a densityd=1.492 in CsCl. Phages of morphological group C3 isolated onEnterobacter sakazakii (C2, C2F) and onErwinia herbicola (E3, E16P) were compared withSalmonella newport phage 7-11 with respect to host-range, genome size, antigenic relatedness, and ultraviolet and heat susceptibility. Phages C2 and C2F could multiply inEnterobacter cloacae, E. sakazakii, Erwinia herbicola, E. rhapontici, andLevinea malonatica; whereas phages E3, E16P, and 7-11 could multiply on these same species and onEscherichia coli and severalSalmonella serotypes. Molecular weights of phage DNAs were determined to be 58×10⁶ (C2), 60×10⁶ (7-11), 67×10⁶ (E3), and 39×10⁶ (E16B).All studied phages of morphological group C3 (includingSalmonella newport phage 7-11) were neutralized by anti-phage C2 serum. Despite differences in neutralization kinetics and in ultraviolet and heat sensitivities, these phages of morphological group C3 constitute one phage species. Phage E16B (morphological group A3) had a host-range limited toEnterobacter cloacae, Erwinia herbicola, andE. rhapontici; it was antigenically unrelated to the preceding phage group C3, and showed ultraviolet and heat susceptibility close to that of coliphage T4.     

Frequency of indicator bacteria,Salmonella and diarrhoeagenic Escherichia coli pathotypes on ready‐to‐eat cooked vegetable salads from Mexican restaurants

The presence of coliform bacteria, faecal coliforms, Escherichia coli, diarrhoeagenic E. coli pathotypes (DEP) and Salmonella were determined in ready‐to‐eat cooked vegetable salads (RECS) from restaurants in Pachuca city, Mexico. The RECS were purchased from three types of restaurants: national chain restaurants (A), local restaurants (B) and small restaurants (C). Two restaurants for each A and B, and three for C, were included. Forty RECS samples were purchased at each A and B restaurant and 20 at each C restaurant. Of the overall total of 220 analysed samples, 100, 98·2, 72·3, 4·1 and 4·1% had coliform bacteria, faecal coliforms, E. coli, DEP and Salmonella, respectively. Identified DEP included enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC) and Shiga toxin‐producing E. coli (STEC). The EPEC, ETEC and STEC were isolated each from 1·4% of samples. No E. coli O157:H7 were detected in any STEC‐positive samples. The analysis of Kruskal–Wallis anova and median test of microbiological data showed that the microbiological quality of RECS did not differ between the different restaurants (P > 0·05).

Significance and Impact of the Study

This is the first report regarding microbiological quality and Salmonella, enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC) and Shiga toxin‐producing E. coli (STEC) isolation from ready‐to‐eat cooked vegetable salads from Mexican restaurants. Ready‐to‐eat cooked vegetable salads could be an important factor contributing to the endemicity of EPEC, ETEC and STEC, and Salmonella caused gastroenteritis in Mexico.     

Efficacy of live B1 or Ulster 2C Newcastle disease vaccines simultaneously vaccinated with inactivated oil adjuvant vaccine for protection of Newcastle disease virus in broiler chickens

Two hundred, one-day-old broiler chicks were divided into groups 1, 2 and 3 containing 60, 70 and 70 chicks, respectively. The groups were divided into subgroups of 10 chicks that were vaccinated according to the following scheme: group 1 unvaccinated control, group 2 vaccinated subcutaneously at 1 day old with inactivated oil adjuvant vaccine (IOAV) in combination with live B1 vaccine. Group 3 was vaccinated in the same mode as group 2 with IOAV and live Ulster 2C vaccine. All birds were challenged when they were 28 days old. Mortality rate, body weight gain and feed conversion ratio (FCR) were monitored before and after challenge. All the chickens in group 1 died, indicating that there was no disease resistance of this unvaccinated control group of chickens. Conversely, the monitored disease resistance of chickens in groups 2 and 3 was 68.57% ± 18.64 and 88.57% ± 9.00, respectively (P < 0.05). The morbidity of chickens in groups 2 and 3 was 37.89% ± 14.36 and 14.76% ± 12.40, respectively (P < 0.05). The body weight gain, feed intake and FCR of group 3 were significantly better than those of group 2 (P < 0.05) during 1–42 days old. The simultaneous vaccination with B1 or Ulster 2C and IOAV of 1-day-old chicks gave some protection of 28-day-old broilers without a booster vaccination.     

High pressure homogenization inactivation of Escherichia coli and Staphylococcus aureus in phosphate buffered saline,milk and apple juice

High pressure homogenization (HPH) offers new opportunities for food pasteurization/sterilization. Escherichia coli and Staphylococcus aureus suspended in phosphate buffered saline (PBS) buffer, milk and apple juice at initial concentration of ~10⁶ log₁₀ CFU per ml were subjected to HPH treatments up to 200 MPa with inlet temperatures at 4–40°C. After HPH at 200 MPa with the inlet temperature at 40°C, the count of E. coli suspended in PBS, milk and apple juice reduced by 3·42, 3·67 and 3·19 log₁₀ CFU per ml respectively while the count of S. aureus decreased by 2·21, 1·02 and 2·33 log₁₀ CFU per ml respectively suggesting that S. aureus was more resistant. The inactivation data were well fitted by the polynomial equation. Milk could provide a protective effect for S. aureus against HPH. After HPH at 200 MPa with the inlet temperature at 20°C, the cell structure of E. coli was destroyed, while no obvious damages were found for S. aureus.