1) could be assigned through a wide range of phylogenetically diverse learn more Actinobacteria. For that reason, as well as the results of the theoretical realignment of

the sequences, the primer system seems to be suitable for diversity analyses. In addition, the primer system was useful for fingerprint analyses such as SSCP (Fig. 2), where our results show different communities of Actinobacteria in the investigated materials. A high diversity as well as heterogeneity of Actinobacteria within the different samples could be detected by SSCP fingerprint analyses, indicating the suitability of the new primer system in ecological investigations. Diversity analyses of the present study in the 18 analysed

water-damaged building materials showed a high variety of members of the class Actinobacteria as evidenced by the detection of 47 different genera. Here, Amycolatopsis, Pseudonocardia, Streptomyces, Saccharopolyspora and Promicromonospora species were detected most frequently. These genera can probably serve as bioindicators of water damage in building materials. Thirteen genera detected by only one clone insert each, showed that these genera are less abundant in water-damaged building materials (Fig. 1). A comparison with genera mentioned in the literature (Anderson et al., 1997; Anderson, 1999; Vuorio et al., 1999; Peltola, 2001; Lorenz et al., 2003a; Rintala et al., 2008) showed that all of the described genera were also detected by the new primer system. Nevertheless, HSP inhibitor clinical trial some genera detected in our study,

for example Amycolatopsis and Jiangella, until now have not been described as colonizers of water-damaged indoor material. The multiple Amobarbital proofs of the specificity of the primer system as well as the wide range of detectable ‘phylogenetically diverse Actinobacteria’ found by the new primer system, indicate that this system seems to be applicable for diversity analyses. Additionally, in comparison with the previously described Actinobacteria-specific primer system developed by Stach et al. (2003), the new primer system showed a greater number of actinobacterial matches at genus level, considering genera which only were detectable using primer set SC-Act-235aS20/SC-Act-878aA19. The similarity coefficient shows a congruent finding of 86%, with a further 8.6% that were only matched using primer system Com2xf/Ac1186r. Furthermore, screening analyses of clone libraries from building material samples using primer system Com2xf/Ac1186r resulted in improved amplification of actinobacterial sequences. Using primer system Com2xf/Ac1186r, more than 87% of the clone inserts were correctly assigned to actinobacterial sequences compared with using the primer system SC-Act-235aS20/SC-Act-878aA19 and a further 11% false positives were detected using the latter primer set.

4B). Compared with other methods that are strongly affected by data size, our RVB method was robust against large variations in data size. The REM method also worked well in relatively broad ranges of Selleck Nutlin-3 the data size. In contrast, NEM and NVB for normal distributions showed no such robustness. In particular, the number of normal distributions (i.e. clusters) increased proportionally to data size when the data was generated by t-distributions (Fig. 4A). The Student’s t-distribution possesses longer tails than the Gaussian

and produced outliers, which could be covered only by an excessive number of normal distributions (Ripley, 1996; Svensén & Bishop, 2005; Archambeau & Verleysen, 2007). The better performance of RVB and REM is consistent with the fact that a t-distribution can be written by an infinite sum of Gaussian distributions (Student, 1908; Lange et al., 1989; Peel & McLachlan, 2000). Although some methods for normal distributions were reasonably good in the analysis of extracellular/intracellular check details recording data, the above results encourage us to use the RVB method. The primary purpose of the present study

was to develop a method to accurately perform spike sorting that requires minimal manual operation. Two types of error in manual operations were previously considered in detail (Harris et al., 2000). Commission errors (or false-positive errors) occur when spikes belonging to different neurons are grouped together, whereas omission errors (or false-negative errors) occur when not all spikes emitted by a single neuron are grouped together. Some human operators made

false-negative errors more often than false-positive errors, whereas others exhibited the opposite tendency. The manual-operation results were significantly impinged by the subjective bias and level of experience of each operator. The RVB-based method could accurately sort simultaneous extracellular/intracellular recording data, generating just a few percent of false-positive and false-negative errors (Fig. 5). We found that smaller values of zth tend to suppress the percentage of false-negative errors at the cost of a small increase in the total error (data not shown). As false negatives can affect spike coincidence analysis more strongly than false positives MTMR9 (Pazienti & Gruen, 2006), a zth value of 0.5 to 0.8 is recommended (here, zth = 0.8). In summary, we developed an accurate and efficient method to spike-sort multi-unit data, based on the WT and RVB. This sorting method significantly improved the reliability of spike sorting to reduce the labor and bias of manual operations. The developed software, EToS, is freely available at http://etos.sourceforge.net/. This work was partially supported by a Grant-in-Aid for Scientific Research on Priority Areas from MEXT (nos. 17022036 and 20019035). T.T. was supported by the RIKEN Special Postdoctoral Researchers Program.

5%), Thailand (35.5%), India (10.3%), Malaysia Ibrutinib purchase (3.7%), Tanzania (3.7%), South Africa (3.7%), Sri Lanka (2.8%), Mozambique (1.9%), Australia (1.9%), and Malawi, Dubai, Mauritius, Kenya, Singapore, Oman, Bahrain, Iran, and United Arab Emirates (all 0.9%). Twenty-two patients had traveled in 2007, 39 in 2008, 23 in 2009, and 23 patients in 2010. Antibodies to CHIKV were detected in sera of eight travelers (7.5%; Table 1). Seven patients had clear evidence of recent infection

(6.5%), based on both IgM- and IgG-positive serology (n = 5), or IgM serology confirmed by PCR and/or NT (n = 2). A second serum sample of one of the two IgM-positive patients showed seroconversion for IgG. One traveler was only IgG positive at a single time point 25 days upon return from the Indian Ocean area. As CHIKV IgM are typically lasting up to 3 months postinfection, this patient probably had prior exposure to CHIKV unrelated to the current complaints for which DENV diagnostics were requested. Of the seven travelers with chikungunya, three had visited Thailand, one had a history of travel to both Thailand and Malaysia, two had traveled to Indonesia, and one to India (Table 1). In total, 6.3% of the male patients and 9.1% selleckchem of the female patients of the cohort showed evidence of a CHIKV infection. The neutralization assay confirmed the presence of CHIKV-specific antibodies in sera of four out of four patients with acute symptoms. For five seropositive

travelers, the remaining amount of serum was insufficient to perform a NT (data not shown). This study demonstrates Molecular motor that in the Netherlands CHIKV infections were substantially underdiagnosed in travelers suspected of dengue

and returning from the Indian Ocean area in the period 2007 to 2010. In 6.5% of the travelers with negative DENV serology, CHIKV appeared to be the etiologic agent. For comparison, of the total of 158 travelers to this region for whom DENV diagnostics were requested, 25.9% showed a positive serology for DENV IgM and/or IgG. As coinfections of humans with DENV and CHIKV have been described, the results of this study potentially underestimate the number of CHIKV cases. Some of the DENV positives could have been coinfected with CHIKV.[2] An analysis of air passenger traffic from CHIKV hotspots to Europe resulted in an estimated annual number of 1,302 viremic travelers from India and Malaysia to the Netherlands,[9] supporting our observation that CHIKV infections are underdiagnosed in the Netherlands as only three CHIKV infections were diagnosed in our laboratory in the period 2009 to 2011 (data not shown). Recently, a similar observation of underdiagnosis was described for Germany.[10] Although infections with DENV or CHIKV are both typified by fever, myalgia, and rash, and the reported incubation periods are similar (4–7 d for DENV, range 3–14 d; 3–7 d for CHIKV, range 1–12 d), other clinical features are clearly different.

To maximize the PPV of a screening test for LTBI, a targeted testing strategy for long-term military Lapatinib mouse and civilian travelers is recommended, based on exposures known to increase the risk of TB. Studies to better define higher risk groups, activities, and locations are needed. Tuberculosis (TB) infection and transmission remain one of the greatest public health threats worldwide. Although the prevalence of TB has greatly decreased

in the temperate and developed nations of Western Europe, North America, Australia, and Japan, it remains a major disease burden in tropical and developing countries.1,2 Consequently, travelers and expatriates from low-prevalence nations who travel or live in high-prevalence nations may become infected with TB.3 In the travel medicine community, however, there is debate about the risk for latent tuberculosis infection (LTBI) that results from long-term travel.4,5 Cobelens and colleagues suggested that

the risk to travelers of acquiring LTBI is similar to that of the general population in the destination country.3 A study among Peace Corps Volunteers from 1996 to 2005 reported an annual infection risk of 0.8% to 1.2% and an active TB incidence density of 68.9 per 100,000 volunteer-years,6 somewhat higher than that for the population of Brazil in 2006 (50/100,000/year).7 In contrast, Rieder suggested that many apparent NVP-BEZ235 latent TB infections in travelers from low-incidence countries to high-incidence countries may be due to false positive tuberculin skin tests (TSTs) in this otherwise low-prevalence population.5 Pseudoepidemics of TST conversions in military populations have been reported in relation to travel,8 as well as in non-traveling Epothilone B (EPO906, Patupilone) civilian populations.9–11 Although the TST is the most well-studied test we have to date

to detect the presence of LTBI, it is not a “gold standard” because it is currently impossible to know if a person is latently infected with a few viable Mycobacterium tuberculosis organisms. Due to the inherent relationship between positive predictive value (PPV) and prevalence of infection, many TST conversions may actually be false positives in a low-risk travel population. Thus, the PPV of a TST conversion in low-risk travelers is probably less than 50%, and may be as little as 16% in the absence of a known exposure to TB.12 As a result of these conflicting estimates of risk and the inherent limitations of the TST, there is uncertainty as to the value of TST screening among long-term travelers, which leads to variability in screening policies and recommendations.

Experiments in mice demonstrated that the mutant strain was less virulent than the parental strain and that it induced a significant immune response in a mouse model when administered intraperitoneally. This may pave the way for developing a live attenuated SEZ-Cap

vaccine that induces protective immunity against both SEZ and PCV2. Further research in pigs is required to confirm protective levels and safety of this vaccine. This study was supported by the National Swine Industry Technology System Foundation (CARS-36), China Postdoctoral Science Foundation (Grant No. 20110490971) and National Natural Science Foundation of China (Grant No. 30871772). Z.W. and Q.F. contributed equally to this paper. “
“Campylobacter-specific bacteriophages (phages) R788 molecular weight are considered as an alternative intervention strategy to decrease the level of poultry contamination with Campylobacter, a leading cause of gastroenteritis worldwide. Eradication efficiency depends primarily on phage-host interaction mediated by phage tail-spike proteins and bacterial receptors. ACP-196 purchase Here, this interaction was characterised using tail-spike gene sequence

analysis, phage neutralisation by antiserum and host range analysis of newly isolated group III Campylobacter phages with 68 Campylobacter jejuni and Campylobacter coli strains. Three different groups of phages were obtained using antibody neutralisation assay, and they were further divided according to polymorphisms observed within tail fibre sequences and host range. Only moderate congruence was observed between these criteria with notable exception of two phages. The infection relied on capsule in all phages isolated, and flagella

were found to influence phage propagation on agar plates, but not in broth. Their specificity was more C. jejuni oriented with tendency to lyse human isolates more efficiently. Additionally, natural resistance of C. jejuni to phages did not correlate with their antibiotic resistance patterns. These findings provide new insights into Campylobacter–phage interaction. “
“Vibrio tapetis is the etiological agent of brown ring disease (BRD) Oxymatrine in clams. Phenotypic, antigenic and genetic variability have been demonstrated, with three groups being established associated with host origin. In this work we analyze the variability of representative strains of these three groups, CECT 4600T and GR0202RD, isolated from Manila clam and carpet-shell clam, respectively, and HH6087, isolated from halibut, on the basis of the whole proteome analysis by 2D-PAGE and multilocus sequence analysis (MLSA). A quantitative analysis of the proteome match coefficient showed a similarity of 79% between the clam isolates, whereas fish isolate showed similarities lower than 70%. A preliminary mass spectrometry (MS) assay allowed the identification of 27 proteins including 50S ribosomal protein L9, riboflavin synthase β subunit, ribose-phosphate pyrophosphokinase and succinyl-CoA synthase α subunit.

, 2003; Rawlings & Johnson, 2007; Rohwerder & Sand, 2007). Biological iron oxidation by this bacterium and other microorganisms, such as members of the genus

Leptospirillum, is the key reaction to regenerate ferric iron, which catalyzes the solubilization of metal ions from sulfide ores. However, the formation of a sulfur layer on the surface of sulfide ores prevents ferric iron from attacking the sulfide–metal bond, resulting in a decrease in bioleaching efficiency (Edwards et al., 2000). Therefore, in addition to iron oxidation, one of the most important processes in bioleaching is microbial sulfur oxidation to prevent the formation of an elemental sulfur layer. Tetrathionate hydrolase (4THase) is one of the key enzymes PI3K Inhibitor Library in the dissimilatory sulfur metabolism of A. ferrooxidans. The 4THase of this bacterium has a maximum activity at pH 3.0–4.0 and is highly stable under acidic conditions (de Jong et al., 1997; Kanao et al., 2007). The catalytic reaction of the enzyme is tetrathionate

hydrolysis, to generate elemental sulfur, thiosulfate, and sulfate. The A. ferrooxidans ATCC23270 4THase gene (Af-tth) was identified by determination of the N-terminal amino acid sequence of the purified protein and searching the whole genome database of the bacterium (Kanao et al., 2007). The gene SRT1720 research buy was composed of 1500 bp nucleotides encoding a 499 amino acid polypeptide. A putative Sec-type signal peptide composed of 32 amino acid residues was observed in the N-terminal of the deduced amino acid sequence of the

ORF. This gene is the same as the previously reported unknown gene encoding for a sulfur-regulated protein associated with the outer membrane fraction from A. ferrooxidans (Buonfiglio et al., 1999). In our hands, the recombinant protein of the 4THase of A. ferrooxidans was synthesized in inclusion bodies and in an inactive form in Escherichia coli harboring a plasmid with Af-tth (Kanao et al., 2007). Development of a method to obtain the active form of the recombinant 4THase will enable us to investigate the following: (1) details of the kinetic and biochemical from properties, (2) crystallization of this unique enzyme, and (3) the amino acid residues essential for the activity. In order to advance characterization of the enzymatic and biological properties of the 4THase, here, we report the expression of the protein in the form of inclusion bodies in E. coli, and the development of a refolding protocol that involves solubilization of the inclusion bodies in concentrated denaturant solutions and subsequent dilution and dialysis to obtain a catalytically active enzyme. Acidithiobacillus ferrooxidans ATCC23270 was grown aerobically on 9K medium (pH 2.5) supplemented with 3% w/v FeSO4·7H2O for genomic DNA preparation. Escherichia coli DH5α (Invitrogen, Carlsbad, CA) was used for DNA manipulation. The cells were grown in a Luria–Bertani medium supplemented with ampicillin (50 μg mL−1).

, 2004). In P. aeruginosa, the human http://www.selleckchem.com/products/bmn-673.html epithelial cell-binding domain of the pilus has been identified in the C-terminal region of pilin (Irvin et al., 1989; Lee et al., 1989; Giltner et al., 2006). Truncated pilin (lacking the first 28 residues) retains the overall structure and biological characteristics of the full-length pilin (Keizer et al., 2001). Considering the high sequence conservation in the N-terminal α-helix domain of pilins between P. aeruginosa and M. xanthus (Li et al.,

2005), the EPS binding domain in M. xanthus pilin was suggested to reside in the C-terminal region, similar to other species. Previous studies in M. xanthus have shown that TFP sheared off from the cell surface are able to bind to purified EPS in vitro (Li et al., 2003). Addition of purified Roxadustat EPS to the EPS-deficient mutant (ΔdifA) restored TFP retraction in this hyperpiliated strain, suggesting that EPS is

able to trigger TFP retraction (Li et al., 2003). In addition, the accumulation of pilin subunits in the membrane was found to reduce the EPS levels produced on the cell surface, probably due to the titration of EPS precursors prior to assembly by the PilA monomer pool (Yang et al., 2010). In this study, by constructing and expressing a truncated M. xanthus PilA (PilACt)-enhanced green fluorescent protein (eGFP) fusion protein, we sought to obtain direct evidence for the specific interaction between TFP and EPS under native conditions. Bacterial strains used in

this study are listed in Table 1. All Escherichia coli strains were grown at 37 °C in Luria–Bertani medium (Fisher). Media were supplemented with ampicillin or kanamycin at 100 μg mL−1 when needed. Myxococcus xanthus cells were grown in CYE medium (Campos et al., 1978) at 32 °C on a rotary shaker at 300 r.p.m. To cultivate biofilms of M. xanthus wild-type strain DK1622, exponentially growing cells were harvested and washed three times with MOPS buffer (Kaiser, 1979), resuspended to an OD600 nm of 1.0 and incubated in sealed containers at 32 °C in the dark for 24 h. Submerged fruiting bodies were cultivated in MMC buffer (Kuner & Kaiser, 1982). Eight-well chambered cover slides (Lab-Tek II Chamber Slide System; Nalge Nunc) were used in this assay as previously Hydroxychloroquine described (Lux et al., 2004). The cell pellets of EPS− strain SW504 (ΔdifA) were directly collected from 24-h CYE liquid culture following 13 000 g centrifugation for 10 min. Plasmids pMXE01, PMXE02 and pMXE03 were constructed for overexpression of the truncated PilA (PilACt), eGFP and eGFP-PilACt fusion proteins, respectively (Table 1). The DNA sequence encoding the C-terminal domain (amino acids 32–208) of the mature M. xanthus PilA was PCR-amplified from the genomic DNA of M. xanthus DK1622 using HPilA32F and HPilA32R primers (Table 1).

[1, 11-13] The higher prevalence of chronic diseases among ethnic minority populations may lead to co-morbidities and multiple drug therapies and consequently medicine-related Selleckchem EPZ-6438 problems (MRPs).[14, 15] Patients from different cultural backgrounds may be expected to have their own perceptions and beliefs which will affect their use

of medicines. In addition, ethnic minority groups are associated with communication and language barriers, and different experiences, needs and expectations than the wider UK population which may also influence their ability to manage their medicines effectively.[16-18] Moreover, it is acknowledged in most healthcare systems that ethnic minority groups have experienced inequalities in health and in accessing healthcare services.[7, 17, 18] There has been extensive research on health problems of ethnic minority groups, especially access to care which can result in differences in health outcomes, but there has been little research which specifically examines medicines use.[19] Also, evidence suggests

that medicines-related needs may be poorly met for these groups.[14, 15, 20-23] Because the definitions of MRPs are wide and include problems ranging from prescribing errors through to obtaining supplies, monitoring for appropriateness and patient behaviours which influence their use, a broad definition of MRPs by Gordon et al.[16] was used in this review to include all these aspects. Gordon et al. defined a MRP as ‘any problem experienced by a patient that may PI3K inhibitors ic50 impact on their ability to manage or take their medicines effectively’.[16] The aim of this review was to establish type(s) and possible contributing factor(s) of MRPs experienced by ethnic minority populations in the UK and to identify interventions or recommendations to support these groups in their use of medicines. Electronic databases of PubMed, Embase, International Pharmaceutical Abstract and Scopus were searched for the period from 1990 to 2011. Reference lists of retrieved articles

and relevant review articles were manually examined for further relevant studies. A hand search of key journals: the International Journal of Pharmacy Practice, Pharmacy World and Science and the Annals of Pharmacotherapy was also performed. Identifying studies of MRPs experienced by ethnic minorities in the UK presented challenges. The review commenced Cytidine deaminase with three main keywords: ‘medicine-related problem’, ‘ethnicity’ and ‘United Kingdom’. Lists of search terms associated with each keyword were generated from MeSH (medical subject heading) terms in PubMed and term-mapping database in Embase. The MeSH terms and map terms provide a consistent way to retrieve information that may use different terminology for the same concepts. Relevant terms were also handpicked from the literature during the course of the review.[24, 25] Keywords not listed as MeSH or map terms were searched as phrases using the free text search mode.

[1, 11-13] The higher prevalence of chronic diseases among ethnic minority populations may lead to co-morbidities and multiple drug therapies and consequently medicine-related EPZ-6438 molecular weight problems (MRPs).[14, 15] Patients from different cultural backgrounds may be expected to have their own perceptions and beliefs which will affect their use

of medicines. In addition, ethnic minority groups are associated with communication and language barriers, and different experiences, needs and expectations than the wider UK population which may also influence their ability to manage their medicines effectively.[16-18] Moreover, it is acknowledged in most healthcare systems that ethnic minority groups have experienced inequalities in health and in accessing healthcare services.[7, 17, 18] There has been extensive research on health problems of ethnic minority groups, especially access to care which can result in differences in health outcomes, but there has been little research which specifically examines medicines use.[19] Also, evidence suggests

that medicines-related needs may be poorly met for these groups.[14, 15, 20-23] Because the definitions of MRPs are wide and include problems ranging from prescribing errors through to obtaining supplies, monitoring for appropriateness and patient behaviours which influence their use, a broad definition of MRPs by Gordon et al.[16] was used in this review to include all these aspects. Gordon et al. defined a MRP as ‘any problem experienced by a patient that may Fulvestrant concentration impact on their ability to manage or take their medicines effectively’.[16] The aim of this review was to establish type(s) and possible contributing factor(s) of MRPs experienced by ethnic minority populations in the UK and to identify interventions or recommendations to support these groups in their use of medicines. Electronic databases of PubMed, Embase, International Pharmaceutical Abstract and Scopus were searched for the period from 1990 to 2011. Reference lists of retrieved articles

and relevant review articles were manually examined for further relevant studies. A hand search of key journals: the International Journal of Pharmacy Practice, Pharmacy World and Science and the Annals of Pharmacotherapy was also performed. Identifying studies of MRPs experienced by ethnic minorities in the UK presented challenges. The review commenced much with three main keywords: ‘medicine-related problem’, ‘ethnicity’ and ‘United Kingdom’. Lists of search terms associated with each keyword were generated from MeSH (medical subject heading) terms in PubMed and term-mapping database in Embase. The MeSH terms and map terms provide a consistent way to retrieve information that may use different terminology for the same concepts. Relevant terms were also handpicked from the literature during the course of the review.[24, 25] Keywords not listed as MeSH or map terms were searched as phrases using the free text search mode.

5 mg), MMW S. Telaviv OPS (II) (4.6 mg) and LMW S. Telaviv OPS (III) (20.3 mg). Their structures, established using chemical methods and NMR spectroscopy (Kumirska et al., 2011), are presented in Fig. 2. This shows that mostly terminal glucose moieties were present in the longer LPS chains, at some distance from the core region, whereas the repeating units directly attached to the core mostly contained http://www.selleckchem.com/products/cetuximab.html a digalactose branching chain. Additionally, the native S. Dakar

and S. Telaviv OPSs were chemically modified by oxidation with NaIO4 and reduction using NaBH4. In the case of S. Dakar OPS, the 4-linked d-galactopyranose and terminal glucopyranose rings in the OPS were cleaved during the first step providing two aldehyde groups in both Galp and Glcp residues, but elimination of the

CO2 moiety from the Glcp unit was also observed (Kumirska et al., 2008). In the next step, the aldehyde products were reduced, giving an open ring structure with two alcohol groups from the above-mentioned sugar residues. The same procedure was applied to the S. Telaviv OPS. As a result, the Talazoparib following periodate-oxidised, and periodate-oxidised and NaBH4-reduced, O-polysaccharides of both bacteria were obtained (Fig. 3). Both aldehyde and reduced species have a polymeric nature and were used for sheep erythrocyte sensitisation without treatment with NaOH. Serological investigations of the native LPSs, the native OPSs and the chemically modified OPSs of S. Dakar and S. Telaviv with polyvalent rabbit antisera S. Dakar (O281, O283), S. Telaviv (O281, O282), S. Adelaide (serogroup O:35) and S. Mara (serogroup O:39), respectively, were performed

in ELISA tests (Table 1). Positive results were obtained for all samples, but polyvalent rabbit antiserum S. Dakar (O281, O283) before cross-reacted with native S. Dakar LPSs and native S. Dakar OPS at higher serum dilutions (log10 4.0) in contrast to native S. Telaviv LPS (log10 3.7) and native S. Telaviv OPS (log10 2.8). On the other hand, polyvalent rabbit antiserum S. Telaviv (O281, O282) displayed higher activities with native S. Dakar LPSs (log10 4.0) and native S. Dakar OPS (log10 3.7) than with its own antigens in a homologous system (log10 3.1 and 2.8 for native LPS S. Telaviv and OPS S. Telaviv respectively). Moreover, very interesting results were obtained for the chemically modified OPSs (periodate oxidised and periodate oxidised then reduced with NaBH4, Fig. 3) of these two bacteria. These samples exhibited the high activities (Table 1) with all the polyvalent rabbit antisera (as well as with S. Adelaide and S. Mara), indicating that terminal glucose, terminal galactose and 4-linked galactose are probably not the antigenic determinant sugars in the subfactors O281, O282 and O283. This information is important because, for example, the O1- and O122-antigenic determinants of Salmonella spp.