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S W Joseph

Publications and source records attributed to S W Joseph.

At least 19 recordsLinked to original sources
PubMed2005

Capsular polysaccharide surrounds smooth and rugose types of Salmonella enterica serovar Typhimurium DT104.

The biofilms and rugose colony morphology of Salmonella enterica serovar Typhimurium strains are usually associated with at least two different exopolymeric substances (EPS), curli and cellulose. In this study, another EPS, a capsular polysaccharide (CP) synthesized constitutively in S. enterica serovar Typhimurium strain DT104 at 25 and 37 degrees C, has been recognized as a biofilm matrix component as well. Fluorophore-assisted carbohydrate electrophoresis (FACE) analysis indicated that the CP is comprised principally of glucose and mannose, with galactose as a minor constituent. The composition differs from that of known colanic acid-containing CP that is isolated from cells of Escherichia coli and other enteric bacteria grown at 37 degrees C. The reactivity of carbohydrate-specific lectins conjugated to fluorescein isothiocyanate or gold particles with cellular carbohydrates demonstrated the cell surface localization of CP. Further, lectin binding also correlated with the FACE analysis of CP. Immunoelectron microscopy, using specific antibodies against CP, confirmed that CP surrounds the cells. Confocal microscopy of antibody-labeled cells showed greater biofilm formation at 25 degrees C than at 37 degrees C. Since the CP was shown to be produced at both 37 degrees C and 25 degrees C, it does not appear to be significantly involved in attachment during the early formation of the biofilm matrix. Although the attachment of S. enterica serovar Typhimurium DT104 does not appear to be mediated by its CP, the capsule does contribute to the biofilm matrix and may have a role in other features of this organism, such as virulence, as has been shown previously for the capsules of other gram-negative and gram-positive bacteria.

Bacterial Capsules↗
PubMed2003

Induction and resuscitation of viable but nonculturable Salmonella enterica serovar typhimurium DT104.

Salmonella enterica serovar Typhimurium DT104 11601 was tested for its ability to maintain viability in minimal, chemically defined solutions. Periodic monitoring of growth and survival in microcosms of different ion concentrations, maintained at various temperatures, showed a gradual decline in culturable organisms ( approximately 235 days) at 5 degrees C. Organisms maintained at a higher temperature (21 degrees C) showed continuous, equivalent CFU per milliliter ( approximately 10(6)) up to 400 days after inoculation. Fluorescence microscopy with Baclight revealed that nonculturable cells were actually viable, while observations with scanning electron microscopy showed that the cells had retained their structural integrity. Temperature upshift (56 degrees C +/- 0.5, 15 s) of the nonculturable organisms (5 degrees C) in Trypticase soy broth followed by immediate inoculation onto Trypticase soy agar (TSA) gave evidence of resuscitation. Interestingly, S. enterica serovar Typhimurium DT104 from the microcosms at either 5 degrees C (1 to 200 days) or 21 degrees C (1 to 250 days) did not show enhanced growth after intermittent inoculation onto catalase-supplemented TSA. Furthermore, cells from 21 degrees C microcosms exposed to oxidative and osmotic stress showed greater resistance to stresses over increasing times of exposure than did recently grown cells. It is possible that the exceptional survivability and resilience of this particular strain may in part reflect the growing importance of this multidrug-resistant organism, in general, as a cause of intestinal disease in humans. The fact that S. enterica serovar Typhimurium DT104 11601 is capable of modifying its physiological characteristics, including entry into and recovery from the viable but nonculturable state, suggests the overall possibility that S. enterica serovar Typhimurium DT104 may be able to respond uniquely to various adverse environmental conditions.

Catalase↗
PubMed2002

Evaluation of chemical disinfectants for the elimination of Salmonella biofilms from poultry transport containers.

Containers used in transporting live poultry between production and processing units are a primary source of contamination for processed poultry products. Because disinfection of transport containers (TC) has been difficult to accomplish, it is probable that the choice of appropriate disinfectant and its application are partially or wholly responsible for the failure to adequately eliminate pathogens from TC. Therefore, 13 commercial disinfectants were selected and evaluated for their capacities to destroy Salmonella. The disinfectants were applied in various concentrations on prescribed areas (10 cm diameter circle) of galvanized steel surfaces (representative of TC material) that were artificially contaminated with Salmonella (10(8) cfu/mL) with a mixture of organic material. Likewise, coupons (1.9 cm2) made of the same metallic surfaces and covered with biofilms of Salmonella spp. were tested in the same manner for each disinfectant. Two of the disinfectants completely eliminated Salmonella on the artificially contaminated and biofilm-covered surfaces. These compounds produced logarithmic reductions in Salmonella populations as high as 7.18 within 2 min. One of the two effective disinfectants contained sodium hypochlorite and was effective at a concentration of 0.05% (vol/vol). The other disinfectant was an alkaline peroxide compound and was effective at a concentration of 1% (wt/vol). Evaluation of these two disinfectants under simulated conditions suggested that application under the prescribed regimen could result in effective elimination of Salmonella from TC within a limited period.

Animals↗
PubMed2001

Salmonella spp. are affected by different levels of water activity in closed microcosms.

Controlling water activity (a(w)) can significantly impact the growth of Salmonella in poultry litter and manure - a phenomenon that was studied quantitatively using two common serotypes of Salmonella. The quantitative effect of changes in levels of a(w) on Salmonella populations was determined using inoculated, frosted glass rectangles placed in closed chambers (microcosms). Glass rectangles with known concentrations of Salmonella enteritidis and S. brandenburg were placed in microcosms maintained at an a(w) level of 0.893 for 24 h at room temperature (RT) and then transferred to other microcosms maintained at the same temperature but with higher a(w) levels (0.932 and 0.987). Salmonella populations on the slides were quantified at 4, 18, 24, and 48 h. Slightly elevated levels of a(w) (<0.1, i.e., 10% equilibrium relative humidity) for 24 h resulted in a 100-fold increase in counts of Salmonella. The data also suggested that in vitro adaptation to dry environments may occur when the organisms are exposed to alternating levels of relatively high and low (0.987 and 0.893) levels of a(w). Any increased tolerance of Salmonella to reduced levels of a(w) could be the result of physico-chemical changes in the organism due to selective environmental pressure, formation of a protective biofilm, and/or entry into a dormant state. Results from this study are compatible with those from previously reported on-farm surveys, reinforcing the contention that maintaining a(w) below 0.85 in and around litter/manure surfaces in poultry or livestock bedding areas may be a critical factor in safe production of food.

Animals↗
PubMed2001

Implications of multiple antimicrobial-resistant enterococci associated with the poultry environment.

Poultry are increasingly being associated with carriage of multiresistant organisms that may cause disease in humans. Among these organisms are the enterococci, not regarded as a common cause of hospital-acquired infections. The use of antimicrobials for growth promotion in poultry production envronments may facilitate the dissemination of resistance to Enterococcus spp. that have the potential to be clinically significant. To assess descriptively the degree of multiresistant enterococci in the poultry environment of the Delmarva (Delaware-Maryland-Virginia) East Coast region of the USA, litter samples from regional commercial poultry houses and transport container swabs from processing facilities were cultured for Enterococcus spp. Using a microtiter plate adaptation of a conventional biochemical screen, the predominant species identfied were E. faecalis (61.2%), E. faecium (18.6%) and E. gallinarum (2.4%). Resistance to the cephalosporin, macrolide and tetracycline classes of antimicrobials was uniform with broader resistance to penicillin and derivatives present in a majority of E. faecium isolates. High-level streptomycin resistance was evident in close to 30% of all isolates with a majority of E. faecalis variants possessing resistance. High-level gentamicin resistance was detected at a low frequency (2.6%) only within the E. faecalis group with resistance to low-level gentamicin levels present in a majority of both the E. faecalis group and subsets of E. faecium. No unexpected vancomycin resistance was detected. Of particular interest was resistance to the streptogramin quinupristin-dalfopristin (Q-D or Synercid), which was present in 70.4% of E. faecium and E. faecium variants.

Animals↗
PubMed2001

Salmonella enterica serovar Typhimurium DT104 displays a rugose phenotype.

Rugose phenotypes, such as those observed in Vibrio cholerae, have increased resistance to chlorine, oxidative stress, and complement-mediated killing. In this study we identified and defined a rugose phenotype in Salmonella enterica serovar Typhimurium DT104 and showed induction only on certain media at 25 degrees C after 3 days of incubation. Incubation at 37 degrees C resulted in the appearance of the smooth phenotype. Observation of the ultrastructure of the rugose form and a stable smooth variant (Stv), which was isolated following a series of passages of the rugose cells, revealed extracellular substances only in cells from the rugose colony. Observation of the extracellular substance by scanning electron microscopy (SEM) was correlated with the appearance of corrugation during development of rugose colony morphology over a 4-day incubation period at 25 degrees C. In addition, the cells also formed a pellicle in liquid broth, which was associated with the appearance of interlacing slime and fibrillar structures, as observed by SEM. The pellicle-forming cells were completely surrounded by capsular material, which bound cationic ferritin, thus indicating the presence of an extracellular anionic component. The rugose cells, in contrast to Stv, showed resistance to low pH and hydrogen peroxide and an ability to form biofilms. Based on these results and analogy to the rugose phenotype in V. cholerae, we propose a possible role for the rugose phenotype in the survival of S. enterica serovar Typhimurium DT104.

Bacterial Capsules↗
PubMed2001

High-frequency recovery of quinupristin-dalfopristin-resistant Enterococcus faecium isolates from the poultry production environment.

The occurrence of resistance to the streptogramin quinupristin-dalfopristin in Enterococcus faecium isolates from chickens on the Eastern Seaboard, was evaluated. Quinupristin-dalfopristin resistance was found in 51 to 78% of E. faecium isolates from the food production environment. The high level of resistance in this organism suggests that this reservoir of resistance may compromise the therapeutic potential of quinupristin-dalfopristin.

Animal Husbandry↗
PubMed2000

A colony lift immunoassay for the specific identification and quantification of Listeria monocytogenes.

A colony lift immunoassay (CLI) has been developed to detect Listeria monocytogenes after the organisms have been cultured on filter membranes or agar plates. Polyvinylidene fluoride membranes (PVDF) (Millipore, Bedford, MA), used in the CLI, were prewet with methanol and used to imprint colonies that were grown on the filter or agar plates. A positive control was applied to the edge of each membrane. The imprinted membranes were subsequently air dried, peroxidase neutralized, blocked, and reacted for 20 min with a 2-microg/ml unconjugated Mab EM-7G1 solution. The membranes were washed briefly and reacted for 30 min with a 1:2000 dilution of a commercially prepared peroxidase-labeled goat anti-mouse secondary antibody (Kirkegaard and Perry Laboratories (KPL), Gaithersburg, MD). After a second wash step, the membranes were exposed to a 3,3',5, 5'-tetramethylbenzidine membrane substrate (KPL), rinsed in deionized water, and allowed to dry. Colonies of L. monocytogenes were identified by a blue color reaction on the membrane, which could be used to reference the colonies either on the filter membranes or agar plates. The CLI was tested against a wide range of Listeria species as well as several non-Listeria species and was shown to have a high degree of sensitivity (96%) and specificity (90%). We have shown that it is useful as a simple and rapid method to detect and identify L. monocytogenes.

Antibodies, Bacterial↗
PubMed2000

Characterization of the contribution of water activity and moisture content to the population distribution of Salmonella spp. in commercial poultry houses.

Because Salmonella spp. can be spread from the production environment to the consumer, strategies are required to control Salmonella. One such intervention involves control of the distribution of the organism in poultry litter. In this regard, we have attempted to determine whether Salmonella spp. are uniformly distributed throughout the litter of commercial poultry houses, or if they are unevenly localized to "hot spots" associated with high surface litter water activity (Aw) and high total moisture levels. Of the 86 houses sampled, 48 (55.8%) were positive for Salmonella spp. using a combination of the drag swab and targeted litter culturing methods. Data are presented that show that elevated Aw and percentage moisture content values representative of targeted litter samples or whole-house moisture status are not statistically predictive of Salmonella contamination, using either drag swab or targeted litter culture results as indicators of contamination. This study suggests that favorable environmental conditions for the growth of Salmonella are unequally dispersed in poultry houses. Because there is not equivalent distribution of salmonellae in the surface litter, the drag swab technique is apparently necessary to adequately survey for Salmonella spp. contamination. The findings further suggest that the development of a methodology to detect areas within houses that possess risk factors favorable for Salmonella growth must also include elevated Aw and percentage moisture content levels. This capability may enable a grower to detect and intervene in these targeted areas with neutralizing procedures, agents, or other substances to provide significant reduction of Salmonella or other poultry-associated food-borne pathogens.

Animals↗
PubMed2000

Improved plating media for the detection of Salmonella species with typical and atypical hydrogen sulfide production.

The Salmonella detection ability of 2 surfactant-supplemental media, xylose-lysine-tergitol (Nia-proof) 4 (XLT4) and Miller-Mallinson (MM) agar, was compared against that of several commonly used plating media. XLT4 and MM appeared to be the most efficient in detecting Salmonella in meat products and food animal environments. MM was superior to XLT4 in detecting those increasingly more prevalent strains of Salmonella possessing weak to ultraweak H2S production characteristics.

Agar↗
PubMed2000

Development and evaluation of a 24-hour method for the detection and quantification of Listeria monocytogenes in meat products.

A 24-h filter monitor-based test, Listeria-SELeCT, has been developed to quantify Listeria monocytogenes organisms in meat samples with a sensitivity of < or = 1.0 CFU/g. The technique comprises a filter monitor-based system and a colony lift immunoassay to identify and enumerate the target organism. Meat homogenates were centrifuged and the eluate was filtered to trap and immobilize the microorganisms on the filter. Fraser broth was then added to the filter apparatus to allow the organisms to become established overnight and to inhibit contaminants, after which the filters were transferred onto Modified Oxford medium agar, a selective medium for L. monocytogenes. After 10 to 12 h, a colony lift immunoassay was used to confirm and enumerate suspect colonies on the filter. A correlation study between the Listeria-SELeCT method and the most probable number technique showed the Listeria-SELeCT to be considerably more accurate than the most probable number for quantitatively determining the number of viable organisms in meat samples. Because of ease and speed of testing, the Listeria-SELeCT system also provided major advantages over the most probable number technology.

Animals↗
PubMed1998

Development of a colony lift immunoassay to facilitate rapid detection and quantification of Escherichia coli O157:H7 from agar plates and filter monitor membranes.

E. coli O157:H7 is a food-borne adulterant that can cause hemorrhagic ulcerative colitis and hemolytic uremic syndrome. Faced with an increasing risk of foods contaminated with E. coli O157:H7, food safety officials are seeking improved methods to detect and isolate E. coli O157:H7 in hazard analysis and critical control point systems in meat- and poultry-processing plants. A colony lift immunoassay was developed to facilitate the positive identification and quantification of E. coli O157:H7 by incorporating a simple colony lift enzyme-linked immunosorbent assay with filter monitors and traditional culture methods. Polyvinylidene difluoride (PVDF) membranes (Millipore, Bedford, Mass.) were prewet with methanol and were used to make replicates of every bacterial colony on agar plates or filter monitor membranes that were then reincubated for 15 to 18 h at 36 +/- 1 degree C, during which the colonies not only remained viable but were reestablished. The membranes were dried, blocked with blocking buffer (Kirkegaard and Perry Laboratories [KPL], Gaithersburg, Md.), and exposed for 7 min to an affinity-purified horseradish peroxidase-labeled goat anti-E. coli O157 antibody (KPL). The membranes were washed, exposed to a 3,3',5,5'-tetramethylbenzidine membrane substrate (TMB; KPL) or aminoethyl carbazole (AEC; Sigma Chemical Co., St. Louis, Mo.), rinsed in deionized water, and air dried. Colonies of E. coli O157:H7 were identified by either a blue (via TMB) or a red (via AEC) color reaction. The colored spots on the PVDF lift membrane were then matched to their respective parent colonies on the agar plates or filter monitor membranes. The colony lift immunoassay was tested with a wide range of genera in the family Enterobacteriaceae as well as different serotypes within the E. coli genus. The colony lift immunoassay provided a simple, rapid, and accurate method for confirming the presence of E. coli O157:H7 colonies isolated on filter monitors or spread plates by traditional culture methods. An advantage of using the colony lift immunoassay is the ability to test every colony serologically on an agar plate or filter monitor membrane simultaneously for the presence of the E. coli O157 antigen. This colony lift immunoassay has recently been successfully incorporated into a rapid-detection, isolation, and quantification system for E. coli O157:H7, developed in our laboratories for retail meat sampling.

Agar↗
PubMed1998

Antibiotic resistance of Escherichia coli O157:H7 and O157:NM isolated from animals, food, and humans.

Antibiotic resistance was determined for 118 E. coli O157:H7 and 7 O157:NM isolates from animals, foods, and humans. Among the 125 isolates, 30 (24%) were resistant to at least one antibiotic and 24 (19%) were resistant to three or more antibiotics. Cattle isolates had the highest rate (34%) of antibiotic resistance. The seven resistant food isolates were all from ground beef. The most frequent resistance type overall was streptomycin-sulfisoxazole-tetracycline, which accounted for over 70% of the resistant strains. Two E. coli O157:NM isolates from cattle were resistant to six antibiotics: ampicillin, kanamycin, sulfisoxazole, streptomycin, tetracycline, and ticarcillin. Streptomycin was the most common antibiotic to which E. coli O157:H7 and O157:NM were resistant (29 out of 30 isolates), followed by tetracycline (26 isolates). This study suggests that E. coli O157:H7 and O157:NM have developed resistance to antibiotics. Research is needed to define mechanisms of antibiotic resistance in E. coli O157:H7 and to minimize the development of resistance.

Animals↗
PubMed1997

Campylobacter jejuni in broiler chickens: colonization and humoral immunity following oral vaccination and experimental infection.

A formalin inactivated, Campylobacter jejuni whole cell vaccine, either with or without Escherichia coli heat labile toxin (LT) as a mucosal adjuvant, was administered orally to broiler chickens. Three vaccine trials were performed, differing in the number of vaccinations, and time of administration, as well as the inclusion and dose of LT. The overall reductions of C. jejuni colonization in the vaccinated chickens ranged from 16 to 93% compared with non-vaccinated controls. Enhanced levels of anti-C. jejuni secretory IgA antibodies were demonstrated in vaccinated chickens. Vaccination also appeared to induce an anamnestic response to C. jejuni antigens in the 14-33 kDa range, as demonstrated by Western immunoblots. Interestingly, the inclusion of LT in the vaccine regimen did not appear to boost the immunogenicity of the vaccine. These results are encouraging and suggest that future development of successful oral vaccines for the control of enteropathogenic Campylobacter in poultry is feasible.

Administration, Oral↗
PubMed1996

Development of a rapid and specific colony-lift immunoassay for detection and enumeration of Campylobacter jejuni, C. coli, and C. lari.

Contamination of retail poultry by Campylobacter spp. is a significant source of human diarrheal disease. We have developed a colony-lift immunoassay (CLI) for the detection of Campylobacter jejuni, C. coli, and C. lari isolated from such sources and grown on selective agar medium or on filter membranes. This technique has been successfully utilized to quantify Campylobacter colonies within 18 to 28 h after sampling. Hydrophobic, high-protein-binding membranes were prewet with methanol and used to imprint bacterial cells from the agar or filter membrane, while leaving colonies intact and viable. The membranes were air dried, peroxidase neutralized, blocked with bovine serum albumin in phosphate-buffered saline, and hybridized for 5 min with an affinity-purified, horseradish peroxidase-labeled goat anti-Campylobacter antibody preparation (Kirkegaard and Perry Laboratories). The membranes were washed briefly, exposed to a 3,'5,5'-tetramethylbenzidine membrane substrate, rinsed in deionized water, and allowed to dry. Lifted colonies of Campylobacter were identified by a blue color reaction on the membrane. Replicas of the membranes were made by marking the location of the Campylobacter colonies on clear transparencies, which were subsequently utilized to locate the original colony on the filter membrane or agar plate. The specificity of this antibody preparation has been evaluated against a wide range of Campylobacter spp., including American Type Culture Collection type and references strains, retail poultry isolates, and isolates obtained from cloacal swabs of live commercial broiler chickens. Specificity against numerous non-Campylobacter spp. obtained from the same sources was also evaluated. The CLI provided a rapid and simple means for detection and enumeration of enteropathogenic Campylobacter organisms. We have successfully combined this CLI procedure with methods recently developed in our laboratories for retail meat and poultry sampling. Potentially, broader applications for use of this technique include detection and enumeration of campylobacters from clinical, veterinary, and environmental samples.

Agar↗
PubMed1995

Recognition of three epitopic regions on invasion plasmid antigen C by immune sera of rhesus monkeys infected with Shigella flexneri 2a.

The invasive ability of Shigella spp. is correlated with the expression of several plasmid-encoded proteins, including invasion plasmid antigen C (IpaC). By characterizing the antigenic structure of IpaC with monoclonal antibodies and convalescent-phase sera, it may be possible to determine the physical location of specific epitopes as well as the involvement of epitopes in a protective immune response or the host's susceptibility to disease. By using overlapping octameric synthetic peptides, which together represent the entire IpaC protein, the precise linear sequence of four surface-exposed epitopes was defined for four IpaC monoclonal antibodies. Furthermore, 17 unique peptide epitopes of IpaC were mapped by using 9-day-postinfection serum samples from 13 rhesus monkeys challenged with Shigella flexneri 2a. Each individual recognized a somewhat different array of IpaC peptide epitopes after infection with shigellae. However, the epitopes were clustered within three regions of the protein: region I (between amino acid residues 1 and 61), region II (between amino acid residues 177 and 258), and region III (between amino acid residues 298 and 307). Region II was recognized by 92% of S. flexneri-infected individuals and was considered to be a highly immunogenic region. Animals asymptomatic for shigellosis after challenge with S. flexneri recognized peptide epitopes within all three epitopic regions of IpaC, whereas symptomatic animals recognized peptides in only one or two of the epitopic regions. Antibody from monkeys challenged with S. sonnei recognized IpaC peptide epitopes which fell within and outside the three S. flexneri epitopic regions. While numerous potential epitopes exist on the IpaC protein, the identification of three regions in which epitopes are clustered suggests that these regions are significant with respect to the immune response and to subsequent pathogenesis postinfection.

Amino Acid Sequence↗
PubMed1994

Development and characterization of recA mutants of Campylobacter jejuni for inclusion in attenuated vaccines.

Isogenic recA mutants of Campylobacter jejuni have been constructed for evaluation of their usefulness in attenuated vaccines against this major worldwide cause of diarrhea. The recA+ gene of C. jejuni 81-176 was cloned by using degenerate primers to conserved regions of other RecA proteins in a PCR. The C. jejuni recA+ gene encodes a predicted protein with an M(r) of 37,012 with high sequence similarity to other RecA proteins. The termination codon of the recA+ gene overlaps with the initiation codon of another open reading frame which encodes a predicted protein which has > 50% identity with the N terminus of the Escherichia coli enolase protein. A kanamycin resistance gene was inserted into the cloned recA+ gene in E. coli and returned to C. jejuni VC83 by natural transformation, resulting in allelic replacement of the wild-type recA gene. The resulting VC83 recA mutant displayed increased sensitivity to UV light and a defect in generalized recombination as determined by natural transformation frequencies. The mutated recA gene was amplified from VC83 recA by PCR, and the product was used to transfer the mutation by natural transformation into C. jejuni 81-176 and 81-116, resulting in isogenic recA mutants with phenotypes similar to VC83 recA. After oral feeding, strain 81-176 recA colonized rabbits at levels comparable to wild-type 81-176 and was capable of eliciting the same degree of protection as wild-type 81-176 against subsequent homologous challenge in the RITARD (removable intestinal tie adult rabbit diarrhea) model.

Amino Acid Sequence↗