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1.
Plant Dis ; 2021 May 17.
Artículo en Inglés | MEDLINE | ID: mdl-33999712

RESUMEN

Ginger (Zingiber officinale Roscoe) is one of the most widely consumed medicinal herb in the world, and the U.S. imports of ginger have risen in recent years because of its health benefits. Seed rhizome and soilborne diseases are serious concerns of ginger worldwide (Stirling 2004; Moreira et al. 2013), including the recent observations of Fusarium yellows and rhizome rot in the Commonwealth of Virginia. In October 2018 and 2019, ginger plants with yellowing of leaf margins and stunted growth were uprooted from a 9.1 m × 14.6 m high tunnel (HT) and from an outdoor raised bed at Virginia State University's Randolph farm. Disease incidence in the HT and the raised bed was estimated between 5-70%. Small pieces (2-5 mm) of symptomatic rhizomes were disinfected with 0.6% sodium hypochlorite solution and placed on potato dextrose agar (PDA) Petri plates to recover fungal isolates. Hyphal tips from these isolates were transferred to fresh PDA to obtain pure cultures. The fungal colonies were pinkish-white initially, and turned purplish-pink after 5-7 days of incubation at 25 °C. The microconidia were aseptate, oval or elliptical, hyaline, and measured 5 to 12 × 4 to 6 µm in size. Macroconidia were with 3 to 5 septations, curved like a sickle towards the ventral side, hyaline, smooth and thin-walled, and 15 to 40 × 3 to 6 µm in size. Fungal genomic DNA of one isolate (Gf-VA-3) was extracted from a 7-days old culture using PrepMan®Ultra (Thermo Fischer Scientific, Cheshire UK). Four conserved regions of the isolated pathogen, internal transcribed spacer (ITS), translation elongation factor (EF), ß-tubulin (Bt), and calmodulin (cal) gene regions were amplified using ITS1 and ITS4 (White et al. 1990), ef1α and ef2α (O'Donnell et al. 1998), Bt2a and Bt2b (Glass and Donaldson 1995), and calA1 and calQ1 (Carbone and Kohn 1999), respectively. PCR products were sequenced, and amplicons deposited in GenBank with accession numbers MT337417 for ITS, MT436712 for Bt, MT802441 for cal and MW816632 for EF. A 99-100% identity with Fusarium oxysporum was matched with accession nos. MW776326 for ITS, MN646766 for the ß-tubulin, MT010904 for the calmodulin and MN258350 for the translation elongation factor genes. For pathogenicity test, six 6-week-old healthy ginger plants grown on sterilized potting mix in the greenhouse were inoculated by injecting 3-ml of a 1 × 108 micro- and macro-conidia suspension per ml at the crown area transcending to the rhizome. Another set of six plants were injected with distilled and autoclaved water in the same way. After four weeks, leaves withered, plants exhibited yellowing and wilt followed by stunted growth and eventually complete collapse of the six inoculated plants, however control plants showed none of the symptoms. The same pathogen was re-isolated from the inoculated plants. The pathogenicity test was repeated, and the same results were observed. Fusarium yellows and rhizome rot has been reported from Hawaii in the U.S. (Trujillo 1963), Brazil (Moreira et al. 2013), Australia (Stirling 2004), China (Li et al. 2014), and India (Shanmugam et al. 2013). To our knowledge, this is the first report of Fusarium yellows and rhizome rot on ginger in the Continental U.S. The disease is seed rhizome and soilborne leading to poor establishment and hence economic loss in ginger production.

2.
BMC Vet Res ; 16(1): 266, 2020 Jul 30.
Artículo en Inglés | MEDLINE | ID: mdl-32731899

RESUMEN

BACKGROUND: Little is known on significance, diversity and characteristics of gut E. coli in goats despite their importance as food animals globally. We characterized the temporal dynamics in diversity of E. coli in fecal samples from a cohort of goat kids and adult meat goats on pasture over a one-year period. Isolates were characterized based on phylogenetic grouping, virulence genes; shiga toxins 1 and 2 (Stx1&Stx2) (STEC), intimin (eaeA), hemolysin (hly) and select important sero-groups (026, 045, 0103, 0126 and 0146) using molecular methods. RESULTS: A total of 516 E. coli isolates were screened. Prevalence of virulence genes and STEC was 65 and 56% respectively. Prevalence of virulence genes and STEC was significantly higher in goat kids less than six months (76% /66%) than adults (48% /28%). Isolates with virulence profiles of two or more genes were also higher in young goat kids (50%) than adults (20%). Entero-pathogenic E. coli (EPEC-eaeA gene only) were mostly from pre-weaned goat kids while hly gene only isolates were significantly higher in adults. The stx1, stx2 and hly genes peaked around weaning (60, 63 and 52%) respectively. Goats kids were mostly hosts to group D (59%) while adults older than one year had B1 (75%) isolates. Group D isolates were most abundant at weaning (64%) and diarrhea samples (74%). Group B2 isolates overall (6%) were mostly detected around weaning (63%) while A isolates were 4% overall. Twenty-four isolates belonged to sero-groups 026, 0103 and 0146 with 70% of the isolates detected around weaning. Nineteen of these isolates were STEC with most harboring the stx1/stx2/hly/eae (25%) profile. Most belonged to O26 sero-group (75%) and phylogroup D (75%). CONCLUSION: To our knowledge this is the first study to highlight longitudinal age related differences in E. coli phylogenetic diversity, abundance of virulence genes and select important sero-groups in goats. Differences detected suggest a possible role of age and weaning stress in influencing E. coli diversity in the gut of goats. The findings are relevant to both animal and public health to advise on further studies on caprine E. coli isolates as animal and human pathogens.


Asunto(s)
Escherichia coli/clasificación , Escherichia coli/genética , Cabras/microbiología , Serogrupo , Adhesinas Bacterianas/genética , Factores de Edad , Animales , Estudios de Cohortes , Diarrea/microbiología , Diarrea/veterinaria , Infecciones por Escherichia coli/veterinaria , Proteínas de Escherichia coli/genética , Heces/microbiología , Femenino , Proteínas Hemolisinas/genética , Estudios Longitudinales , Masculino , Filogenia , Toxinas Shiga/genética , Virulencia/genética , Destete
3.
Avian Pathol ; 44(5): 408-20, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-26223977

RESUMEN

Polyvalent infectious bronchitis virus vaccination is common worldwide. The possibility of vaccine interference after simultaneous combined vaccination with Arkansas (Ark) and Massachusetts (Mass)-type vaccines was evaluated in an effort to explain the high prevalence of Ark-type infectious bronchitis virus in vaccinated chickens. Chickens ocularly vaccinated with combinations of Ark and Mass showed predominance of Mass vaccine virus before 9 days post-vaccination (DPV) in tears. Even when Mass and Ark vaccines were inoculated into separate eyes, Mass vaccine virus was able to outcompete Ark vaccine virus. Although Mass vaccine virus apparently had a replication advantage over Ark vaccine in ocular tissues, Ark vaccine virus appeared to have an advantage in spreading to and/or replicating in the trachea. When chickens vaccinated with Ark or Mass vaccine were housed together, Mass vaccine virus was able to spread to Ark-vaccinated chickens, but the Ark vaccine was not detected in Mass-vaccinated chickens. Only Mass vaccine was detected in tears of sentinel birds introduced into groups receiving both vaccines. Furthermore, Ark vaccine virus RNA was not detectable until 10 DPV in most tear samples from chickens vaccinated with both Ark and Mass vaccines at varying Ark vaccine doses, while high concentrations of Mass virus RNA were detectable at 3-7 DPV. In contrast, Ark vaccine virus replicated effectively early after vaccination in chickens vaccinated with Ark vaccine alone. The different replication dynamics of Ark and Mass viruses in chickens vaccinated with combined vaccines did not result in reduced protection against Ark challenge at 21 DPV. Further studies are needed to clarify if the viral interference detected determines differences in protection against challenge at other time points after vaccination.


Asunto(s)
Infecciones por Coronavirus/veterinaria , Virus de la Bronquitis Infecciosa/inmunología , Enfermedades de las Aves de Corral/prevención & control , Vacunación , Vacunas Virales/inmunología , Animales , Arkansas , Pollos , Infecciones por Coronavirus/prevención & control , Infecciones por Coronavirus/virología , Modelos Animales de Enfermedad , Virus de la Bronquitis Infecciosa/genética , Virus de la Bronquitis Infecciosa/aislamiento & purificación , Virus de la Bronquitis Infecciosa/fisiología , Massachusetts , Enfermedades de las Aves de Corral/virología , ARN Viral/aislamiento & purificación , Análisis de Secuencia de ADN , Serogrupo , Organismos Libres de Patógenos Específicos , Vacunas Combinadas , Replicación Viral
4.
Avian Dis ; 58(1): 102-10, 2014 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-24758121

RESUMEN

Factors responsible for the persistence of Arkansas Delmarva Poultry Industry (ArkDPI)-derived infectious bronchitis vaccines in commercial flocks and the high frequency of isolation of ArkDPI-type infectious bronchitis viruses in respiratory cases are still unclear. We compared dynamics of vaccine viral subpopulations, viral loads, persistence in trachea and cloaca, and the magnitude of infectious bronchitis virus (1BV)-specific antibody induction after vaccination with two commercial ArkDPI-derived Arkansas (Ark) serotype vaccines. One of the vaccines (coded vaccine B) produced significantly higher vaccine virus heterogeneity in vaccinated chickens than the other vaccine (coded A). Chickens vaccinated with vaccine B had significantly higher viral loads in tears at 5 days postvaccination (DPV) than those vaccinated with vaccine A. Vaccine B also induced a significantly higher lachrymal immunoglobulin M response at 11 DPV, an earlier peak of IBV-specific lachrymal immunoglobulin A, and higher serum antibodies than vaccine A. In addition, a significantly higher proportion of birds vaccinated with vaccine B had vaccine virus detected in the trachea at 20 DPV than those vaccinated with vaccine A. Furthermore, the virus detected at 20 DPV in most of the chickens vaccinated with vaccine B was a single specific subpopulation (subpopulation 4) selected from multiple vaccine subpopulations detected earlier at 5 and 7 DPV in the same chickens. On the other hand, a higher proportion of chickens vaccinated with vaccine A had virus detected in cloacal swabs at 20 DPV. Thus we found differences in mucosal antibody induction and selection and persistence of vaccine viruses between two ArkDPI-derived vaccines from different manufacturers. The higher vaccine virus heterogeneity observed in chickens vaccinated with vaccine B compared with those vaccinated with vaccine A may be responsible for these differences. Thus the high frequency of Ark IBV viruses in the field may be due to the inherent ability of some ArkDPI-derived vaccine viruses to be selected and persist in vaccinated chickens. Vaccine virus persistence may offer genetic material for recombination or may undergo mutations with the potential to result in increased virulence.


Asunto(s)
Pollos , Infecciones por Coronavirus/veterinaria , Virus de la Bronquitis Infecciosa/genética , Enfermedades de las Aves de Corral/inmunología , Enfermedades de las Aves de Corral/virología , Vacunas Virales/inmunología , Animales , Anticuerpos Antivirales/metabolismo , Cloaca/inmunología , Cloaca/patología , Cloaca/virología , Infecciones por Coronavirus/inmunología , Infecciones por Coronavirus/patología , Infecciones por Coronavirus/virología , Ensayo de Inmunoadsorción Enzimática/veterinaria , Inmunoglobulina A/metabolismo , Inmunoglobulina M/metabolismo , Virus de la Bronquitis Infecciosa/clasificación , Virus de la Bronquitis Infecciosa/aislamiento & purificación , Masculino , Datos de Secuencia Molecular , Enfermedades de las Aves de Corral/patología , ARN Mensajero/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/veterinaria , Análisis de Secuencia de ADN/veterinaria , Análisis de Secuencia de Proteína/veterinaria , Organismos Libres de Patógenos Específicos , Glicoproteína de la Espiga del Coronavirus/genética , Lágrimas/inmunología , Lágrimas/virología , Tráquea/inmunología , Tráquea/patología , Tráquea/virología , Vacunas Atenuadas/genética , Vacunas Atenuadas/inmunología , Carga Viral/veterinaria , Vacunas Virales/genética
5.
Antibiotics (Basel) ; 13(6)2024 May 29.
Artículo en Inglés | MEDLINE | ID: mdl-38927171

RESUMEN

The emergence of antimicrobial-resistant (AMR) bacteria has become a critical global One Health issue, mainly attributed to the extensive use of antimicrobial agents in human and agricultural settings. Regional and local AMR surveillance data is essential for implementing awareness and mitigation strategies. This article assesses AMR frequency in 1604 bacterial isolates consisting of Escherichia coli (E. coli) and Salmonella spp. isolated from diverse sources in Virginia, including farm animals, wildlife, environment, and food samples from 2007 to 2021. The results are based on the Kirby-Bauer disc diffusion assessment method of susceptibility to select antimicrobial agents, spanning nine distinct categories approved by the US Food and Drug Administration for clinical use. Streptomycin (STR) and tetracycline (TCY) exhibited the highest frequency of resistance in E. coli (39.1%) and Salmonella (25.2%), respectively. Multidrug resistance (MDR) was evident in 6.6% of E. coli and 10.9% of Salmonella isolates. Notably, 51% of E. coli and 36% of Salmonella isolates demonstrated resistance to more than one antimicrobial. None of the tested antimicrobials guaranteed effectiveness against the bacteria isolated from the surveyed sources and regions. The study found heightened MDR and distinct AMR patterns in bacteria isolated from food products compared to other sampled sources. These findings are vital for comprehending the current AMR landscape, prompting the development of strategies to mitigate the emergence of AMR bacteria, and advocating prudent antimicrobial use from a One Health perspective.

6.
Artículo en Inglés | MEDLINE | ID: mdl-39098850

RESUMEN

The potential benefit of probiotics in small ruminant production systems has largely been unexplored. We evaluated the effect of a goat commercial probiotic on health and performance indicators in pastured goats from birth until 10 months. We randomly allocated 26 newborn nursing goat kids to two groups: a control group that received saline and a treatment group that received a commercial probiotic paste orally. We evaluated select observable health indicators (inappetence, diarrhea, coughing), weight, immunity (IgA, IgG, and innate immune response), total protein, hematocrit (HCT), total lactic acid bacteria (LAB), total coliforms, and prevalence of Escherichia coli (E. coli) primary virulence genes (stx1, stx2, and eae) during the experimental period. The results revealed no significant differences in the health indicators, LAB count, and total E. coli count. Prevalence of stx1 at 1 week of age and both stx1 and stx2 genes 4 months post-weaning was significantly (P < 0.05) higher in probiotic-supplemented goats. Probiotic supplementation significantly (P < 0.05) increased the total protein and IgA 1 month post-supplementation during the pre-weaning period and innate immune markers 2 days post-weaning. The HCT in probiotic-supplemented goats was significantly (P < 0.05) higher at 1 and 2 months post-weaning. The growth rate was not affected by probiotic supplementation in pre- and peri-weaned goats but was significantly (P < 0.05) lowered in goats older than 4 months in the supplemented group. In this pastured goat production study, there were mixed responses to a commercial probiotic in healthy goats based on age. The study suggests that early daily probiotic supplementation in pre-weaned pastured goats may have immune stimulation benefits, but in older healthy animals, post-weaning net benefits are unclear and further research is recommended.

7.
Antibiotics (Basel) ; 13(3)2024 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-38534658

RESUMEN

While environmental factors may contribute to antimicrobial resistance (AMR) in bacteria, many aspects of environmental antibiotic pollution and resistance remain unknown. Furthermore, the level of AMR in Escherichia coli is considered a reliable indicator of the selection pressure exerted by antimicrobial use in the environment. This study aimed to assess AMR variance in E. coli isolated from diverse environmental samples, such as animal feces and water from wastewater treatment plants (WWTPs) and drainage areas of different land use systems in Central Virginia. In total, 450 E. coli isolates obtained between August 2020 and February 2021 were subjected to susceptibility testing against 12 antimicrobial agents approved for clinical use by the U.S. Food and Drug Administration. Approximately 87.8% of the tested isolates were resistant to at least one antimicrobial agent, with 3.1% showing multi-drug resistance. Streptomycin resistance was the most common (73.1%), while susceptibility to chloramphenicol was the highest (97.6%). One isolate obtained from WWTPs exhibited resistance to seven antimicrobials. AMR prevalence was the highest in WWTP isolates, followed by isolates from drainage areas, wild avians, and livestock. Among livestock, horses had the highest AMR prevalence, while cattle had the lowest. No significant AMR difference was found across land use systems. This study identifies potential AMR hotspots, emphasizing the environmental risk for antimicrobial resistant E. coli. The findings will aid policymakers and researchers, highlighting knowledge gaps in AMR-environment links. This nationally relevant research offers a scalable AMR model for understanding E. coli ecology. Further large-scale research is crucial to confirm the environmental impacts on AMR prevalence in bacteria.

8.
Pathogens ; 12(7)2023 Jul 23.
Artículo en Inglés | MEDLINE | ID: mdl-37513812

RESUMEN

In food desert areas, low-income households without convenient transportation often shop at small, independently owned corner markets and convenience stores (SIOMs). Studies indicate a higher potential for reduced product quality and safety of foods sold at SIOMs, with more critical and non-critical code violations in the region. This study aimed to assess the difference in market scale on the microbiological quality in select food products procured from food deserts in Central Virginia. A total of 326 samples consisting of meat products (i.e., ground beef, chicken, and sausage), ethnic food products (i.e., ox tail, stock fish bite, egusi ground, and saffron powder), and food packaging surfaces procured from ten registered SIOMs and nine large chain supermarkets (LCSMs) between August 2018 and March 2020 were evaluated. Higher levels of aerobic mesophile and coliform counts were found in SIOMs-acquired samples than in LCSMs-acquired samples, as demonstrated by the lower food safety compliance rate of SIOMs. Regardless of SIOMs or LCSMs, Campylobacter, E. coli, Listeria, and Salmonella were detected in 3.6%, 20.9%, 5.5%, and 2.7% of samples, respectively. The majorities of Campylobacter (75%, 6/8) and Salmonella (83.3%, 5/6) detected were from SIOMs-acquired samples including ethnic food products. Among the tested antimicrobials, AMP (100%) and TOB (100%) showed the highest frequency of resistance among Campylobacter, TCY (69.9%) among E. coli, NAL (100%) among Listeria, and TCY (50%) among Salmonella, respectively. The prevalence of multi-drug resistance (MDR) and non-susceptibility in Campylobacter and non-susceptibility in Listeria isolated from SIOMs-acquired food products were lower than those isolated from LCSMs-acquired samples. A higher price of the same brand name commodity sold at SIOMs than those sold at LCSMs was also observed, indicating an increased financial burden to economically challenged residents in food desert areas, in addition to food safety concerns. Elaborated and in-depth research on a larger-scale sample size with a greater diversity of products is needed to determine and intervene in the cause(s) of the observed differences in the prevalence of the pathogens and AMR profiles.

9.
Animals (Basel) ; 13(16)2023 Aug 19.
Artículo en Inglés | MEDLINE | ID: mdl-37627460

RESUMEN

Understanding gut lactic acid bacteria (LAB) in healthy hosts is an important first step in selecting potential probiotic species. To understand the dynamics of LAB in healthy goats, a cohort of thirty-seven healthy new-born goat kids was studied over a ten-month period. Total LAB was quantified using SYBR green qPCR. Seven hundred LAB isolates were characterized using microscopy, M13 RAPD genotyping and 16S rDNA sequencing. The highest and lowest LAB counts were detected at one week and ten months of age, respectively. Diverse LAB species were detected, whose identity and prevalence varied with age. The main isolates belonged to Limosilactobacillus reuteri, Limosilactibacillus fermentum, Lactobacillus johnsonni, Ligilactobacillus murinus, Ligilactobacillus salivarius, Limosilactobacillus mucosae, Lactiplantibacillus plantarum, Ligilactobacillus agilis, Lactobacillus acidophilus/amyolovolus, Pediococcus spp. and Enterococcus spp. Uniquely, L. reuteri and Pediococcus spp. were most common in pre- and peri-weaned goats, while Lactobacillus mucosae and Enterococcus spp. were predominant in goats one month and older. Based on RAPD genotyping, L. reuteri had the highest genotypic diversity, with age being a factor on the genotypes detected. This data may be relevant in the selection of age-specific probiotics for goats. The findings may also have broader implications by highlighting age as a factor for consideration in probiotic bacteria selection in other animal hosts.

10.
Avian Dis ; 56(4): 642-53, 2012 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-23397834

RESUMEN

We investigated the significance of differing proportions of specific subpopulations among commercial Arkansas (Ark) Delmarva poultry industry (DPI) vaccines with regard to vaccination outcome. Two ArkDPI-derived vaccines that contain a higher proportion of viruses with S1 genes that become selected during replication in chickens exhibited more rapid establishment of those selected subpopulations in chickens, produced significantly higher viral loads in tears, and induced higher antibody responses compared with two other ArkDPI vaccines with lower proportions of viruses that become selected in chickens. The presence of higher proportions of selected subpopulations was also associated with a significantly higher incidence of respiratory signs early after vaccination and in some cases more severe tracheal lesions. However, one of the ArkDPI-derived vaccines with a lower proportion of selected subpopulations, despite producing a lower viral load in tears, also induced a higher incidence of respiratory signs later after vaccination and more severe tracheal lesions. Furthermore, one of the ArkDPI-derived vaccines with a higher proportion of selected subpopulations, despite producing a higher viral loads in tears, resulted in less severe tracheal damage. These discrepancies suggest that infectious bronchitis virus (IBV) load in tears may not always predict degree of tracheal damage and that phenotypic characteristics other than S1 may also be involved in severity of vaccine reactions following ArkDPI vaccine administration. We observed lower antibody responses to the vaccines that produced lower viral loads, which might contribute to the persistence of Ark serotype IBV vaccines observed in commercial flocks.


Asunto(s)
Pollos , Infecciones por Coronavirus/veterinaria , Virus de la Bronquitis Infecciosa/genética , Enfermedades de las Aves de Corral/inmunología , Enfermedades de las Aves de Corral/virología , Vacunas Virales/inmunología , Animales , Anticuerpos Antivirales/metabolismo , Infecciones por Coronavirus/inmunología , Infecciones por Coronavirus/patología , Infecciones por Coronavirus/virología , Glándula de Harder/virología , Inmunoglobulina G/metabolismo , Virus de la Bronquitis Infecciosa/clasificación , Virus de la Bronquitis Infecciosa/aislamiento & purificación , Interferón gamma/metabolismo , Glicoproteínas de Membrana/química , Glicoproteínas de Membrana/genética , Datos de Secuencia Molecular , Enfermedades de las Aves de Corral/patología , ARN Mensajero/genética , Sistema Respiratorio/inmunología , Sistema Respiratorio/patología , Sistema Respiratorio/virología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/veterinaria , Análisis de Secuencia de ADN/veterinaria , Análisis de Secuencia de Proteína/veterinaria , Organismos Libres de Patógenos Específicos , Glicoproteína de la Espiga del Coronavirus , Lágrimas/virología , Vacunas Atenuadas/genética , Vacunas Atenuadas/inmunología , Proteínas del Envoltorio Viral/química , Proteínas del Envoltorio Viral/genética , Carga Viral/veterinaria , Vacunas Virales/genética
11.
Microorganisms ; 10(9)2022 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-36144444

RESUMEN

Understanding Shiga toxin subtypes in E. coli from reservoir hosts may give insight into their significance as human pathogens. The data also serve as an epidemiological tool for source tracking. We characterized Shiga toxin subtypes in 491 goat E. coli isolates (STEC) from the mid-Atlantic US region (stx1 = 278, stx2 = 213, and stx1/stx2 = 95). Their serogroups, phylogroups, M13RAPD genotypes, eae (intimin), and hly (hemolysin) genes were also evaluated. STEC-positive for stx1 harbored Stx1c (79%), stx1a (21%), and stx a/c (4%). Those positive for Stx2 harbored stx2a (55%) and Stx2b (32%), while stx2a/stx2d and stx2a/stx2b were each 2%. Among the 343 STEC that were serogrouped, 46% (n = 158) belonged to O8, 20% (n = 67) to 076, 12% (n = 42) to O91, 5% (n = 17) to O5, and 5% (n = 18) to O26. Less than 5% belonged to O78, O87, O146, and O103. The hly and eae genes were detected in 48% and 14% of STEC, respectively. Most belonged to phylogroup B1 (73%), followed by D (10%), E (8%), A (4%), B2 (4%), and F (1%). M13RAPD genotyping revealed clonality of 091, O5, O87, O103, and O78 but higher diversity in the O8, O76, and O26 serogroups. These results indicate goat STEC belonged to important non-O157 STEC serogroups, were genomically diverse, and harbored Shiga toxin subtypes associated with severe human disease.

12.
Food Sci Nutr ; 7(6): 2033-2042, 2019 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-31289651

RESUMEN

Improper food processing is one of the major causes of foodborne illness. Accurate prediction of the thermal destruction rate of foodborne pathogens is therefore vital to ensure proper processing and food safety. When bacteria are subjected to pH and thermal stresses during growth, sublethal stresses can occur that may lead to differences in their subsequent tolerance to thermal treatment. As a preliminary study to test this concept, the current study evaluated the effect of prior pH and thermal stresses on thermal tolerance of Salmonella and Staphylococcus using a tryptic soy broth supplemented with yeast extract. Bacteria incubated at three pH values (6.0, 7.4, and 9.0) and four temperatures (15, 25, 35, and 45°C) for 24 hr were subjected to thermal treatments at 55, 60, and 65°C. At the end of each treatment time, bacterial suspensions were surface-plated on standard method agar for quantification of bacterial survival and further calculation of the thermal death decimal reduction time (D-value) and thermal destruction temperature (z-value). The effect of pH stress alone during the incubation on the thermal tolerance of both bacteria was generally insignificant. An increasing pattern of D-value was observed with the increment of thermal stress (incubation temperature). The bacteria incubated at 35°C required the highest z-value to reduce the 90% in D-values. Staphylococcus mostly displayed higher tolerance to thermal treatment than Salmonella. Although further research is needed to validate the current findings on food matrices, findings in this study clearly affirm that adaptation of bacteria to certain stresses may reduce the effectiveness of preservation procedures applied during later stage of food processing and storage.

13.
Antibiotics (Basel) ; 8(3)2019 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-31480769

RESUMEN

There is a scarcity of information on antibiotic resistance in goats. To understand shedding of resistant Escherichia coli in pastured goats, we collected fecal samples from a mixed age cohort over a one-year period. No antibiotic had been used on the study animals one year prior to and during the study period. Resistant isolates were detected in all age groups and prevalence in goat kids was significantly higher than adults; 43-48% vs 8-25% respectively. The proportion of resistant isolates was higher when animals were congregated near handling facility than on pasture. Most isolates were resistant to tetracycline (51%) and streptomycin (30%), but also to antibiotics that had never been used on the farm; ampicillin (19%). TetB, bla-TEM, (aadA and strpA/strpB) genes were detected in 70%, 43%, (44% and 24%) of tetracycline, ampicillin, and streptomycin resistant isolates respectively. Resistant isolates also harbored virulent genes and some belonged to D and B2 phylogenetic groups. Thus, pastured goats, despite minimal exposure to antibiotics, are reservoirs of resistant E. coli that may contaminate the environment and food chain and spread resistant genes to pathogenic bacteria and some that are potential animal and human pathogens. Environmental sources may play a role in acquisition of resistant bacteria in pastured goats.

14.
Food Sci Nutr ; 7(12): 4027-4036, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31890183

RESUMEN

Accurate prediction of the thermal destruction rate of foodborne pathogens is important for food processors to ensure proper food safety. When bacteria are subjected to thermal stress during storage, sublethal stresses and/or thermal acclimation may lead to differences in their subsequent tolerance to thermal treatment. The aim of the current study was to evaluate the thermal tolerance of Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica, and Staphylococcus aureus that are incubated during overnight growth in tryptic soy broth at four temperatures (15, 25, 35, and 45°C). Following incubation, the bacteria were subjected to thermal treatments at 55, 60, and 65°C. At the end of each treatment time, bacterial survival was quantified and further calculated for the thermal death decimal reduction time (D-value) and thermal destruction temperature (z-value) using a linear model for thermal treatment time (min) vs. microbial population (Log CFU/ml) and thermal treatment temperature (°C) vs. D-value, respectively, for each bacterium. Among the four bacterial species, E. coli generally had longer D-values and lower z-values than did other bacteria. Increasing patterns of D- and z-values in Listeria were obtained with the increment of incubation temperatures from 15 to 45°C. The z-values of Staphylococcus (6.19°C), Salmonella (6.73°C), Listeria (7.10°C), and Listeria (7.26°C) were the highest at 15, 25, 35, and 45°C, respectively. Although further research is needed to validate the findings on food matrix, findings in this study clearly affirm that adaptation of bacteria to certain stresses may reduce the effectiveness of preservation hurdles applied during later stages of food processing and storage.

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