Prevalence of enterotoxins and toxin gene profiles of Staphylococcus aureus isolates recovered from a bakery involved in a second staphylococcal food poisoning occurrence

AIMS

The study objective was to characterize and analyse the distribution of enterotoxins and genes encoding enterotoxins in Staphylococcus aureus strains recovered from the 601 environment and ingredient samples obtained during multiple inspections of a bakery implicated in two separate staphylococcal food poisoning incidents.

METHODS AND RESULTS

Staphylococcus aureus isolates were evaluated using serological assays for identification of classical staphylococcal enterotoxins (SEs) SEA-SEE and polymerase chain reaction for the detection of newly described SE and SE-like enterotoxin genes seg-seu. Pulsed field gel electrophoresis identified thirteen pattern types. During these investigations, a total of 585 environmental swabs and 16 raw ingredient samples were collected by investigators, 85 of which were confirmed to contain Staph. aureus; of those isolates, 95·3% (81/85) harboured enterotoxin genes and 4·7% (4/85) carried newly described SE and SE-like enterotoxin genes in the absence of classical enterotoxins.

CONCLUSIONS

Our research demonstrates the prevalence and diversity of classical SEs and the probable underestimated impact of nonclassical SE and SE-like enterotoxins role in domestic staphylococcal food poisoning outbreaks.

SIGNIFICANCE AND IMPACT OF THE STUDY

Given the abundance of SEs and SE-like toxins, these findings illustrate the utilization of PCR for enterotoxin gene identification and its significance in outbreak investigations.

Highly diverse variable number tandem repeat loci in the E. coli O157:H7 and O55:H7 genomes for high-resolution molecular typing

AIM

Evaluation of the Escherichia coli genome for variable number tandem repeat (VNTR) loci in order to provide a subtyping tool with greater discrimination and more efficient capacity.

METHODS AND RESULTS

Twenty-nine putative VNTR loci were identified from the E. coli genomic sequence. Their variability was validated by characterizing the number of repeats at each locus in a set of 56 E. coli O157:H7/HN and O55:H7 isolates. An optimized multiplex assay system was developed to facility high capacity analysis. Locus diversity values ranged from 0.23 to 0.95 while the number of alleles ranged from two to 29. This multiple-locus VNTR analysis (MLVA) data was used to describe genetic relationships among these isolates and was compared with PFGE (pulse field gel electrophoresis) data from a subset of the same strains. Genetic similarity values were highly correlated between the two approaches, through MLVA was capable of discrimination amongst closely related isolates when PFGE similar values were equal to 1.0.

CONCLUSIONS

Highly variable VNTR loci exist in the E. coli O157:H7 genome and are excellent estimators of genetic relationships, in particular for closely related isolates.

SIGNIFICANCE AND IMPACT OF THE STUDY

Escherichia coli O157:H7 MLVA offers a complimentary analysis to the more traditional PFGE approach. Application of MLVA to an outbreak cluster could generate superior molecular epidemiology and result in a more effective public health response.

Attitudes of Japanese students toward people with intellectual disability

BACKGROUND

The purpose of the present study was to gain insight into the structure and organization of the attitudes of Japanese students toward people with intellectual disability (ID). The study also examined how these attitudes are related to individual characteristics, such as experience with people with ID, major field of study and career interests.

METHODS

The participants completed a series of measures developed in the USA: three measures of attitudes toward people with ID, a demographic questionnaire and a social desirability scale. Students completed the measures anonymously.

RESULTS

The factor structures of all three attitude scales replicated the structures found in the USA. Attitudes toward the community inclusion of people with ID were negatively correlated with an endorsement of eugenics. Students in social work and psychology had more positive attitudes than other students. Participants who expressed an interest in a career working with people with ID had more positive attitudes than students with no interest in such a career.

CONCLUSIONS

Attitude measures developed in the USA can be used in Japan, and can provide useful information as well as an opportunity for cross-cultural comparisons. For a more complete understanding of the attitudes of Japanese people toward people with ID, these attitudes should also be studied using measures based in Japanese culture which have specifically developed to measure attitudes in Japan.

Molecular investigation of the Aum Shinrikyo anthrax release in Kameido, Japan

In 1993, the Aum Shinrikyo cult aerosolized Bacillus anthracis spores over Kameido, Japan. Spore samples were obtained from the release site, cultured, and characterized by molecular genetic typing. The isolates were consistent with strain Sterne 34F2, which is used in Japan for animal prophylaxis against anthrax.

Assessing perceived agency adherence to the values of community inclusion: implications for staff satisfaction

Measures of staff members' knowledge (N = 518) of the values of community inclusion, perception of agency adherence to community inclusion, and satisfaction with relevant components of their jobs were developed. Staff represented 130 agencies in a state-wide program of individualized community living supports for adults with developmental and/or mental disabilities. Results suggest relatively high levels of knowledge about values of inclusion and perceived agency adherence to the inclusion philosophy among employees regarding the need to provide individuals who have disabilities with opportunities for engaging in community daily activities and their rights for services. Employees, however, had significantly less knowledge of and noted less agency adherence to activities intended to provide consumers with opportunities to make choices. Staff who perceived more agency adherence to the philosophy of inclusion were more satisfied with their jobs.

Attitudes of community-living staff members toward persons with mental retardation, mental illness, and dual diagnosis

Attitudes of 340 staff members in 120 community living programs for people with mental retardation, mental illness, and dual diagnosis and a comparison sample of 152 community members were assessed using the Community Living Attitudes Scale, a measure of attitudes toward inclusion. Results showed that community agency supervisory and managerial staff held more favorable attitudes toward community living philosophy. Community support staff who worked with people who have mental retardation saw that population as less similar to other people than did the comparison sample and were less likely to endorse exclusion of persons with mental retardation than were those in the comparison sample. Retrospective analyses showed that training in inclusion philosophy was related to more inclusive, empowering attitudes among staff members.

The Community Living Attitudes Scale, Mental Retardation Form: development and psychometric properties

We described the development and psychometric properties of the Community Living Attitudes Scale, Mental Retardation Form (CLAS-MR), a 40-item measure based on the input of self-advocates and focused on contemporary community living philosophies. The CLAS-MR, which consists of four subscales that tap attitudes about people with mental retardation, demonstrated acceptable internal consistency, retest reliability, and construct validity with samples of 104 college students and 283 community members. Using data from a sample of 355 staff members from community agencies, we confirmed the factor structure of the measure. Given the importance of attitudes toward persons with mental retardation in policy making and community inclusion, the CLAS-MR can help chronicle the diffusion of the new paradigm of empowered community living for persons with mental retardation.

Ice-skating injuries to the hand

166 patients with injuries due to ice-skating were seen in the local accident and emergency department over a six-month period; 60% of these involved the upper limb. 28 of the upper limb injuries were closed fractures and 24 were lacerations, almost all to the dorsum of the hand. The use of protective gloves would help to prevent these potentially avoidable injuries. "On-site" first-aid facilities help to reduce the demand on the local accident service.

Ice-Skating Injuries to the Hand

166 patients with injuries due to ice-skating were seen in the local accident and emergency department over a six-month period; 60% of these involved the upper limb. 28 of the upper limb injuries were closed fractures and 24 were lacerations, almost all to the dorsum of the hand. The use of protective gloves would help to prevent these potentially avoidable injuries. “On-site” first-aid facilities help to reduce the demand on the local accident service.

Conformational determinants of high affinity delta receptor binding of opioid peptides

Detailed conformational analysis of linear and cyclic delta-selective opioid peptides was performed in conjunction with computer-analyzed receptor binding studies with the aim of determining conformational requirements for high affinity binding of peptides to the delta-receptor. The four linear delta-selective hexapeptides included in this study were: DSLET (Tyr-D-Ser-Gly-Phe-Leu-Thr) and its D-Thr2 analog (DTLET) and two t-butyl ether analogs. In one analog an O-t-butyl group replaces the D-Ser2OH and in the other a second O-t-butyl group replaces the D-Thr6OH group as well. This study also includes seven cyclic pentapeptides of the type: Tyr-Cys(Pen-Gly-Phe-Cys(Pen) with various combinations of DL-cysteine and DL-penicillamine (beta-dimethyl cysteine) as the second and fifth residues resulting in varying delta affinities and selectivities. Four (DPLPE, DPDPE, DPLCE, and DCLPE) have both high delta affinity and selectivity; two (DCDCE and DCLCE) have high affinity at both delta- and mu-receptors, and one (LCLCE) has low affinity for both receptors. Our investigation has shown that all analogs that have high affinity at the delta receptor have a unique common low energy conformer. This compact conformer contains intramolecular H-bonds and is very different from the beta II-turn-type structure associated with high affinity mu-receptor binding deduced in our previous work.

The immune response of the lacrimal gland to antigenic exposure

This study probed the influence of antigenic exposure on the immunological response of the lacrimal gland. We utilized the germfree rat as a model system to monitor tissue and tear immunoglobulin changes following transfer of these animals into an antigen-laden, conventional environment. The number of IgA- and IgM-containing cells in the lacrimal glands of germfree rats was 5 to 8 fold less than that of conventional controls. This reduced immunological expression in germfree animals also extended to tear IgA levels, which were significantly decreased. No effect of germfree conditions was found on the tear content of secretory component (SC). Transfer of rats from a germfree to a conventional environment resulted in a significant increase in the number of IgA- and IgM-containing cells in the lacrimal gland. By four weeks after 'conventionalization', the number of Ig-containing cells in lacrimal tissue was similar in both ex-germfree and conventional rats. In addition, 'conventionalization' led to a significant increase in the tear content of IgA: within four weeks following exposure to a conventional environment, tear IgA levels in ex-germfree rats were equivalent to those of age-matched, conventional controls. Overall, our results demonstrate that the secretory immune system of the lacrimal gland reacts to antigenic challenge with an increased immunological response.

Structure-activity studies of morphiceptin analogs: receptor binding and molecular determinants of mu-affinity and selectivity

In this study we report the systematic investigation of conformational profiles and electronic properties of a series of analogs of the mu-selective opioid peptide, morphiceptin, together with receptor-binding studies of some of these analogs. In particular, we have investigated the effect of: substitution in the second position, substitution of D-Pro for L-Pro in the second and fourth positions, the addition of an N-methyl group at the third position, and variations in the carboxyl end group. The binding studies confirm the preference of these analogs for mu- versus delta-receptor-binding sites and also indicate differences in mu-receptor affinity among them. The theoretical analyses allow identification of a preferred conformation leading to high mu-receptor affinity and two reliable indicators of relative mu-receptor affinities. These properties are the energy required to obtain the candidate mu-binding conformer and the extent to which each compound overlaps with the highest affinity compound in this conformation. In addition, electronic interactions deleterious to high affinity mu-binding are identified.

The use of computer analysis in describing multiple opiate receptors

The computer curve fitting program LIGAND has been used to simultaneously analyze 50 competition experiments using five labeled opioid ligands. The results describe four or five distinct sites, although the maximum number of sites cannot be determined. A site with high affinity for all the compounds tested, similar to the mu 1 site described by Pasternak, was apparent in 4 and 5-site models.

Computer-assisted determination of benzodiazepine receptor heterogeneity

The presence of benzodiazepine receptor heterogeneity was investigated on whole rat brain membranes, at 0 degree C, using computerized, weighted nonlinear least-squares regression analysis. Data from [3H]flunitrazepam and [3H] beta-carboline ethyl ester self and cross-competition studies were analyzed simultaneously with data from the inhibition of both labeled ligands by various known and novel benzodiazepine receptor ligands. The binding model which best fits the data indicated the presence of at least two independent binding sites. The benzodiazepines flunitrazepam and 2'-Cl-diazepam showed a small difference in affinity at the two sites. The beta-carbolines and Cl 218,872 showed a larger difference in affinity, and had higher affinities at the lower affinity site for the benzodiazepines. Analogous experiments could be useful in the determination of the effect of GABA on benzodiazepine receptor affinities.

Computer-assisted analysis of receptor-binding studies of [3H]-naloxone and [3H]-DADL: a reinterpretation of the Na+ effect

Computer-assisted analysis of competitive binding studies of [3H]-naloxone, [3H]-DADL, morphine and meperidine in the presence and absence of 100 mM NaCl have been made. The results are most consistent with a 3-site model of opiate receptors and indicate that in the presence of Na+ naloxone changes from a mu-specific (81%) to a more kappa-specific (63%) ligand. The large IC50 shift in inhibition of [3H]-naloxone by three agonists, DADL, morphine and meperidine is found not to be due to a decrease in affinity at any receptor site but rather to a low affinity of these agonists at "kappa" in the presence of Na+.

Detailed receptor binding studies of a series of N-substituted ethyl 3-arylnipecotates

Receptor-binding studies with [3H]-naloxone and [3H]-DADL have been made for a series of 3-arylpiperidines known to have moderate analgesic agonist and antagonist activities. All analogues were found to bind selectively to the opiate "mu" receptor with affinities consistent with their in vivo activity. However, Na+ did not appreciably alter their IC50 values in competition with [3H]-naloxone, independent of their relative agonist/antagonist activity. This anomaly is consistent with our previous theoretical studies of these 3-phi piperidines which postulated different modes of agonist and antagonist receptor binding than that for fused ring opiates. Computer-assisted analysis of the binding shows that this low IC50 ratio is probably due to a greatly enhanced affinity of these analogues at a third site in the presence of Na+, behavior parallel to that of naloxone.

Hemin does not cause commitment of murine erythroleukemia (MEL) cells to terminal differentiation

The effect of hemin on the differentiation program of murine erythroleukemia (MEL) cells has been investigated. While hemin treatment does induce increased levels of globin mRNA and hemoglobin, it fails to lead to other biochemical changes associated with MEL cell differentiation induced by DMSO and thioguanine. These include increased levels of the nuclear protein IP25 and of the enzyme cytidine deaminase. Clonal analysis of hemin-treated cells revealed that unlike other inducers, hemin does not cause a reprogramming of MEL cells to a specific limitation of proliferative capacity. These observations suggest that hemin differs from DMSO and thioguanine in that it exerts specific effects on globin expression in MEL cells without triggering commitment to the terminal differentiation program.

Isolation and localization of DNA segments from specific human chromosomes

Recombinant DNA techniques have been combined with somatic cell genetic methods to identify, isolate, and amplify fragments of human DNA localized at specific regions of human chromosome 11 selected as a model system. A library of genomic DNA segments has been constructed, in lambda Charon 4A bacteriophage, from the DNA of a somatic cell hybrid carrying a portion of human chromosome 11 on a Chinese hamster ovary cell background. Using a nucleic acid hybridization technique that distinguishes human and Chinese hamster interspersed, repetitive DNA, we have been able to distinguish recombinant phages carrying DNA segments of human origin from recombinant phages carrying DNA segments of Chinese hamster origin. We have isolated 50 human DNA segments thus far and have characterized 5 in detail. For each DNA segment characterized, a subsegment that carries no repetitive human DNA sequences has been identified. These segments have been used as hybridization probes in experiments that localize the DNA fragment on the chromosome. In each case an unequivocal chromosomal localization has been obtained with reference to a panel of hybrid cell clones each of which carries a deletion of a portion of the short arm of chromosome 11. At least one DNA segment has been identified which maps to each of the four regions on the short arm defined by the panel of hybrid cell clones used. The approaches described here appear to be general. They can be extended to produce a fine structure map of human chromosome 11 and other human chromosomes. This approach promises implications for human genetics generally, for the human genetic diseases, and possibly for understanding of gene regulation in normal and abnormal differentiation.

The organization of a nuclear DNA sequence from a higher plant: molecular cloning and characterization of soybean ribosomal DNA

The recombinant DNA vector, lambda Charon 4A, was used to construct a library of DNA sequences from the genomic DNA of soybean (Glycine max). To define the organization of ribosomal DNA (rDNA) in the soybean genome, clones containing sequences complementary to both 17S and 25S rRNA have been isolated from this library and used in conjunction with Southern blot hybridization. The rRNA genes are tandemly reiterated with a relatively small unit repeat length of 7.8 kb. There is no heterogeneity in the length of the rDNA repeat units although they display limited differences in either base sequence or pattern of methylation. The cloned rDNA sequences are shown to comprise the entire repeat unit and have been used to obtain a detailed restriction map as well as an approximate transcription map of soybean rRNA genes. The cloning of rDNA from soybean suggests that recombinant DNA techniques can be successfully applied to the genomic DNA of higher plants despite the high degree of methylation exhibited by plant DNA.

Precise localization of human beta-globin gene complex on chromosome 11

Cloned DNA probes were used in combination with a panel of five hybrid cell clones containing a series of different terminal deletions in human chromosome 11 to map precisely the human hemoglobin beta and delta chain structural genes contained on this chromosome. The region of deletion in each clone of the panel has been defined by biochemical, immunologic, and cytogenetic markers. DNA from clones containing successively larger terminal deletions was tested with appropriate DNA probes to determine the point on the chromosome at which DNA for these two closely linked hemoglobin genes is deleted. These genes, and by inference the closely linked G gamma and A gamma globin genes as well, have been assigned to the intraband region 11p1205 leads to 11p1208 on the short arm of chromosome 11, an interval containing approximately 4500 kilobases of DNA. The approach appears to have potential for even greater resolution and reasonably wide applicability for gene mapping.