Husbandry conditions of spotted ratfish (Hydrolagus colliei, Chimaeriformes) in aquaria for successful embryonic development and long-term survival of juveniles

The spotted ratfish Hydrolagus colliei is the most common holocephalan species exhibited in aquaria worldwide for introducing deep-sea environments and raising awareness of their conservation. However, little is known about the biology of H. colliei. Current practices in aquaria allow long-term survival of sexually mature H. colliei specimens; however, this species struggles to complete a reproductive cycle in captivity mostly because embryos do not reach the hatchling stage. The aquarists of Planet Ocean Montpellier (POM, France) have bred H. colliei for 15 years and recorded parameters suitable for this species' successful embryonic and post-embryonic development. POM aquarists now regularly record egg-laying events of H. colliei and use four tanks to incubate eggs and raise neonates, late hatchlings, early and intermediate juveniles, subadults, and sexually mature specimens. In this work we provide the first long-term biometric data on H. colliei from the hatchling to the subadult stage. We also report the biotic and abiotic parameters sufficient to breed H. colliei in aquaria. We finally describe the methods used to facilitate individual monitoring of specimens along the ontogeny and several pathologies identified in this species, their putative causes, and the corresponding treatments. This work highlights the importance of ex situ research and points to the valuable outcomes of collaborative efforts between aquaria and academia in deciphering the biology of species whose study in the wild remains challenging.

Biodegradable fibre scaffolds incorporating water-soluble drugs and proteins

A new type of biodegradable drug-loaded fibre scaffold has been successfully produced for the benefit of water-soluble drugs and proteins. Model drug loaded calcium carbonate (CaCO3) microparticles incorporated into poly(lactic acid-co-glycolic acid) (PLGA) fibres were manufactured by co-precipitation of CaCO3 and the drug molecules, followed by electrospinning of a suspension of such drug-loaded microparticles in a PLGA solution. Rhodamine 6G and bovine serum albumin were used as model drugs for our release study, representing small bioactive molecules and protein, respectively. A bead and string structure of fibres was achieved. The drug release was investigated with different drug loadings and in different pH release mediums. Results showed that a slow and sustained drug release was achieved in 40 days and the CaCO3 microparticles used as the second barrier restrained the initial burst release.

[Blood donor hemovigilance: impact for donor and recipient safety]

Since its creation in 1993, hemovigilance has an important place for blood safety. The part concerning donors, as the name suggests, targeted on improvement of donor's safety covers in fact the two points of the transfusion chain with serious adverse events in donor, epidemiologic survey for recipients and post-donation information on the two sides. Organized management and close collaboration between the actors of the transfusion chain are necessary to ensure the effectiveness of the system.

Multi-scale mechanical characterization of scaffolds for heart valve tissue engineering

Electrospinning is a promising technology to produce scaffolds for cardiovascular tissue engineering. Each electrospun scaffold is characterized by a complex micro-scale structure that is responsible for its macroscopic mechanical behavior. In this study, we focus on the development and the validation of a computational micro-scale model that takes into account the structural features of the electrospun material, and is suitable for studying the multi-scale scaffold mechanics. We show that the computational tool developed is able to describe and predict the mechanical behavior of electrospun scaffolds characterized by different microstructures. Moreover, we explore the global mechanical properties of valve-shaped scaffolds with different microstructural features, and compare the deformation of these scaffolds when submitted to diastolic pressures with a tissue engineered and a native valve. It is shown that a pronounced degree of anisotropy is necessary to reproduce the deformation patterns observed in the native heart valve.

[The management of post donation information: a fundamental element of blood safety]

Post donation information management is a fundamental axis of haemovigilance in terms of blood safety. It requires an organization ensuring a permanent reactivity, a good sensitization of French National Blood Service professionals and needs also a strong awareness of blood donors. Previous identification of stakeholders to warn during these kinds of alerts is essential to avoid the use of any blood product presenting a potential risk. The recent implementation of a consensual internal document aims to target the reinforcement of a homogeneous decision-making process, combining blood product self-sufficiency and above all recipient safety.

Toll-like receptor 2 is critical for induction of Reg3 beta expression and intestinal clearance of Yersinia pseudotuberculosis

OBJECTIVE

Yersinia pseudotuberculosis causes ileitis and mesenteric lymphadenitis by mainly invading the Peyer's patches that are positioned in the terminal ileum. Whereas toll-like-receptor 2 (TLR2) controls mucosal inflammation by detecting certain microbiota-derived signals, its exact role in protecting Peyer's patches against bacterial invasion has not been defined.

DESIGN

Wild-type, Tlr2-, Nod2- and MyD88-deficient animals were challenged by Y pseudotuberculosis via the oral or systemic route. The role of microbiota in conditioning Peyer's patches against Yersinia through TLR2 was assessed by delivering, ad libitum, exogenous TLR2 agonists in drinking water to germ-free and streptomycin-treated animals. Bacterial eradication from Peyer's patches was measured by using a colony-forming unit assay. Expression of cryptdins and the c-type lectin Reg3 beta was quantified by quantitative reverse transcriptase polymerase chain reaction analysis.

RESULTS

Our data demonstrated that Tlr2-deficient mice failed to limit Yersinia dissemination from the Peyer's patches and succumbed to sepsis independently of nucleotide-binding and oligomerisation domain 2 (NOD2). Recognition of both microbiota-derived and myeloid differentiation factor 88 (MyD88)-mediated elicitors was found to be critically involved in gut protection against Yersinia-induced lethality, while TLR2 was dispensable to systemic Yersinia infection. Gene expression analyses revealed that optimal epithelial transcript level of the anti-infective Reg3 beta requires TLR2 activation. Consistently, Yersinia infection triggered TLR2-dependent Reg3 beta expression in Peyer's patches. Importantly, oral treatment with exogenous TLR2 agonists in germ-free animals was able to further enhance Yersinia-induced expression of Reg3 beta and to restore intestinal resistance to Yersinia. Lastly, genetic ablation of Reg3 beta resulted in impaired clearance of the bacterial load in Peyer's patches.

CONCLUSIONS

TLR2/REG3 beta is thus an essential component in conditioning epithelial defence signalling pathways against bacterial invasion.

Skeletal myogenesis on highly orientated microfibrous polyesterurethane scaffolds

Skeletal myogenesis is a complex process, which is known to be intimately depending on an optimal outside-in substrate-cell signaling. Current attempts to reproduce skeletal muscle tissue in vitro using traditional scaffolds mainly suffer from poor directionality of the myofibers, resulting in an ineffective vectorial power generation. In this study, we aimed at investigating skeletal myogenesis on novel biodegradable microfibrous scaffolds made of DegraPol, a block polyesterurethane previously demonstrated to be suitable for this application. DegraPol was processed by electrospinning in the form of highly orientated ("O") and nonorientated ("N/O") microfibrous meshes and by solvent-casting in the form of nonporous films ("F"). The effect of the fiber orientation at the scaffold surface was evaluated by investigating C2C12 and L6 proliferation (via SEM analysis and alamarBlue test) and differentiation (via RT-PCR analysis and MHC immunostaining). We demonstrated that highly orientated elastomeric microfibrous DegraPol scaffolds enable skeletal myogenesis in vitro by aiding in (a) myoblast adhesion, (b) myotube alignment, and (c) noncoplanar arrangement of cells, by providing the necessary directional cues along with architectural and mechanical support.

Describing ancient horizontal gene transfers at the nucleotide and gene levels by comparative pathogenicity island genometrics

MOTIVATION

Lateral gene transfer is a major mechanism contributing to bacterial genome dynamics and pathovar emergence via pathogenicity island (PAI) spreading. However, since few of these genomic exchanges are experimentally reproducible, it is difficult to establish evolutionary scenarios for the successive PAI transmissions between bacterial genera. Methods initially developed at the gene and/or nucleotide level for genomics, i.e. comparisons of concatenated sequences, ortholog frequency, gene order or dinucleotide usage, were combined and applied here to homologous PAIs: we call this approach comparative PAI genometrics.

RESULTS

YAPI, a Yersinia PAI, and related islands were compared with measure evolutionary relationships between related modules. Through use of our genometric approach designed for tracking codon usage adaptation and gene phylogeny, an ancient inter-genus PAI transfer was oriented for the first time by characterizing the genomic environment in which the ancestral island emerged and its subsequent transfers to other bacterial genera.

The pmrF polymyxin-resistance operon of Yersinia pseudotuberculosis is upregulated by the PhoP-PhoQ two-component system but not by PmrA-PmrB, and is not required for virulence

The Yersinia pseudotuberculosis chromosome contains a seven-gene polycistronic unit (the pmrF operon) whose products share extensive homologies with their pmrF counterparts in Salmonella enterica serovar Typhimurium (S. typhimurium), another Gram-negative bacterial enteropathogen. This gene cluster is essential for addition of 4-aminoarabinose to the lipid moiety of LPS, as demonstrated by MALDI-TOF mass spectrometry of lipid A from both wild-type and pmrF-mutated strains. As in S. typhimurium, 4-aminoarabinose substitution of lipid A contributes to in vitro resistance of Y. pseudotuberculosis to the antimicrobial peptide polymyxin B. Whereas pmrF expression in S. typhimurium is mediated by both the PhoP-PhoQ and PmrA-PmrB two-component regulatory systems, it appears to be PmrA-PmrB-independent in Y. pseudotuberculosis, with the response regulator PhoP interacting directly with the pmrF operon promoter region. This result reveals that the ubiquitous PmrA-PmrB regulatory system controls different regulons in distinct bacterial species. In addition, pmrF inactivation in Y. pseudotuberculosis has no effect on bacterial virulence in the mouse, again in contrast to the situation in S. typhimurium. The marked differences in pmrF operon regulation in these two phylogenetically close bacterial species may be related to their dissimilar lifestyles.

Insights into the evolution of Yersinia pestis through whole-genome comparison with Yersinia pseudotuberculosis

Yersinia pestis, the causative agent of plague, is a highly uniform clone that diverged recently from the enteric pathogen Yersinia pseudotuberculosis. Despite their close genetic relationship, they differ radically in their pathogenicity and transmission. Here, we report the complete genomic sequence of Y. pseudotuberculosis IP32953 and its use for detailed genome comparisons with available Y. pestis sequences. Analyses of identified differences across a panel of Yersinia isolates from around the world reveal 32 Y. pestis chromosomal genes that, together with the two Y. pestis-specific plasmids, to our knowledge, represent the only new genetic material in Y. pestis acquired since the the divergence from Y. pseudotuberculosis. In contrast, 149 other pseudogenes (doubling the previous estimate) and 317 genes absent from Y. pestis were detected, indicating that as many as 13% of Y. pseudotuberculosis genes no longer function in Y. pestis. Extensive insertion sequence-mediated genome rearrangements and reductive evolution through massive gene loss, resulting in elimination and modification of preexisting gene expression pathways, appear to be more important than acquisition of genes in the evolution of Y. pestis. These results provide a sobering example of how a highly virulent epidemic clone can suddenly emerge from a less virulent, closely related progenitor.

Superantigen bacterial toxins: state of the art

Superantigens (SAgs) are viral and bacterial proteins exhibiting a highly potent polyclonal lymphocyte-proliferating activity for CD4(+), CD8(+) and sometimes gammadelta(+) T cells of human and (or) various animal species. Unlike conventional antigens, SAgs bind as unprocessed proteins to invariant regions of major histocompatibility complex (MHC) class II molecules on the surface of antigen-presenting cells (APCs) and to particular motifs of the variable region of the beta chain (Vbeta) of T-cell receptor (TcR) outside the antigen-binding groove. As a consequence, SAgs stimulate at nano-to picogram concentrations up to 10 to 30% of host T-cell repertoire while only one in 10(5)-10(6) T cells (0.01-0.0001%) are activated upon conventional antigenic peptide binding to TcR. SAg activation of an unusually high percentage of T lymphocytes initiates massive release of pro-inflammatory and other cytokines which play a pivotal role in the pathogenesis of the diseases provoked by SAg-producing microorganisms. We briefly describe in this review the molecular and biological properties of the bacterial superantigen toxins and mitogens identified in the past decade.

Silencing and reactivation of urease in Yersinia pestis is determined by one G residue at a specific position in the ureD gene

Yersinia pestis, the plague agent, is a naturally nonureolytic microorganism, while all other Yersinia species display a potent urease activity. In this report we demonstrate that Y. pestis harbors a complete urease locus composed of three structural (ureABC) and four accessory (ureEFGD) genes. Absence of ureolytic activity is due to the presence of one additional G residue in a poly(G) stretch, which introduces a premature stop codon in ureD. The presence of the same additional G in eight other Y. pestis isolates indicates that this mutation is species specific. Spontaneous excision of the extra G occurs at a frequency of 10(-4) to 10(-5) and restores a ureolytic phenotype to Y. pestis. The virulence of two independent ureolytic clones of Y. pestis injected either intravenously, subcutaneously, or intragastrically did not differ from that of the parental strain in the mouse infection model. Coinfection experiments with an equal number of ureolytic and nonureolytic bacteria did not evidence any difference in the ability of the two variants to multiply in vivo and to cause a lethal infection. Altogether our results demonstrate that variation of one extra G residue in ureD determines the ureolytic activity of Y. pestis but does not affect its virulence for mice or its ability to multiply and disseminate.

The superantigenic toxin of Yersinia pseudotuberculosis: a novel virulence factor?

Recently, a superantigenic toxin designated YPM (Yersinia pseudotuberculosis-derived mitogen) was characterized in the supernatant of Y. pseudotuberculosis, a Gram-negative bacterium involved in human enteric infection. To assess the role of YPM in pathophysiology of Y. pseudotuberculosis, a superantigen-deficient mutant was constructed and its virulence was tested in a murine model of infection and compared with the virulence of the wild-type strain (wt). Determination of the survival rate after intravenous inoculation of mice clearly demonstrated a higher survival rate when animals were infected with the superantigen-deficient strain. This decreased virulence of the mutant strain could not be explained by a lower bacterial growth rate in spleen, liver or lung of infected animals. Therefore, production of IFNgamma, TNFalpha, IL-2, IL-6 and IL-10 was followed during the course of infection by cytokine assay in the blood and mRNA detection in the spleen. IL-6 and IFNgamma were the two major cytokines detected whereas TNFalpha production was never observed.

Superantigen YPMa exacerbates the virulence of Yersinia pseudotuberculosis in mice

Yersinia pseudotuberculosis, a gram-negative bacterium responsible for enteric and systemic infection in humans, produces a superantigenic toxin designated YPMa (Y. pseudotuberculosis-derived mitogen). To assess the role of YPMa in the pathogenesis of Y. pseudotuberculosis, we constructed a superantigen-deficient mutant and compared its virulence in a mouse model of infection to the virulence of the wild-type strain. Determination of the survival rate after intravenous (i.v.) bacterial inoculation of OF1 mice clearly showed that inactivation of ypmA, encoding YPMa, reduced the virulence of Y. pseudotuberculosis. Mice infected i.v. with 10(4) and 10(5) wild-type bacteria died within 9 days, whereas mice infected with the ypmA mutant survived 12 and 3 days longer, respectively. This decreased virulence of the ypmA mutant strain was not due to an impaired colonization of the spleen, liver, or lungs. In contrast to i.v. challenge, bacterial inoculation by the intragastric (i.g.) route did not reveal any difference in virulence between wild-type Y. pseudotuberculosis and the ypmA mutant since the 50% lethal doses were identical for both strains. Moreover, inactivation of ypmA gene did not affect the bacterial growth of Y. pseudotuberculosis in Peyer's patches, mesenteric lymph nodes (MLNs), and spleen after oral infection. Histological studies of spleen, liver, lungs, heart, Peyer's patches, and MLNs after i.v. or i.g. challenge with the wild type or the ypmA mutant did not reveal any feature that can be specifically related to YPMa. Our data show that the superantigenic toxin YPMa contributes to the virulence of Y. pseudotuberculosis in systemic infection in mice.

Molecular epidemiology of tuberculosis in the Nord Department of France during 1995

In order to determine the current situation and to evaluate the human to human transmission of Mycobacterium tuberculosis in Northern France, the genetic polymorphism of strains was studied by using IS6110 fingerprint. One hundred and fifty-eight cases of bacteriologically confirmed tuberculosis were analyzed. One hundred and twenty-six patients (82%) were infected with genetically different isolates and 28 isolates (18%) were grouped into 14 clusters. No risk factors for recent Mycobacterium tuberculosis infections such as age, HIV status, immigrants, living in big cities were identified. This study shows that there was no major epidemic situation of tuberculosis in Northern France in 1995. Tuberculosis was characterized by a low proportion of HIV positive patients and a high proportion of elderly patients.

Cytotoxic T-cell-mediated response against Yersinia pseudotuberculosis in HLA-B27 transgenic rat

Yersinia-induced reactive arthritis is highly associated with HLA-B27, the role of which in defense against the triggering bacteria remains unclear. The aim of this study was to examine the capacity of rats transgenic for HLA-B27 to mount a cytotoxic T-lymphocyte (CTL) response against Y. pseudotuberculosis and to determine the influence of the HLA-B27 transgene on this response. Rats transgenic for HLA-B*2705 and human beta(2)-microglobulin of the 21-4L line, which do not spontaneously develop disease, and nontransgenic syngeneic Lewis (LEW) rats were infected with Y. pseudotuberculosis. Lymph node cells were restimulated in vitro, and the presence of for Y. pseudotuberculosis-specific CTLs against infected targets was determined. Infection of 21-4L rats triggered a CD8(+) T cell-mediated cytotoxic response specific for Y. pseudotuberculosis. Analysis of this response demonstrated restriction by an endogenous major histocompatibility complex molecule. However, no restriction by HLA-B27 was detected. In addition, kinetics studies revealed a weaker anti-Yersinia CTL response in 21-4L rats than in nontransgenic LEW rats, and the level of cytotoxicity against 21-4L lymphoblast targets sensitized with Y. pseudotuberculosis was lower than that against nontransgenic LEW targets. We conclude that HLA-B27 transgenic rats mount a CTL response against Y. pseudotuberculosis that is not restricted by HLA-B27. Yet, HLA-B27 exerts a negative effect on the level of this response, which could contribute to impaired defense against Yersinia.

Characterization of IS1541-like elements in Yersinia enterocolitica and Yersinia pseudotuberculosis

We characterized Yersinia enterocolitica and Yersinia pseudotuberculosis insertion sequences related to insertion sequence 1541, recently identified in Yersinia pestis. For each of the two species, two insertion sequence copies were cloned and sequenced. Genetic elements from Y. pseudotuberculosis were almost identical to insertion sequence 1541, whereas these from Y. enterocolitica were less related. Phylogenetic analysis of the putative transposases encoded by insertion sequences from the three pathogenic members of the genus Yersinia showed that they clustered with those encoded by Escherichia coli and Salmonella enterica elements belonging to the insertion sequence 200/insertion sequence 605 group. Insertion sequences originating from Y. pestis and Y. pseudotuberculosis constitute a monophyletic lineage distinct from that of Y. enterocolitica.

PCR detection of aminoglycoside resistance genes: a rapid molecular typing method for Acinetobacter baumannii

Aminoglycoside resistance is common among strains of Acinetobacter baumannii responsible for nosocomial infections, and inactivation of these antibiotics by enzymatic modification is the main mechanism. Different types of aminoglycoside acetyltransferases (AAC), nucleotidyltransferases (ANT), and phosphotransferases (APH) are synthesized by clinical isolates, and several enzymes can be produced by a single strain. Using a multiplex PCR procedure carried out on bacterial thermolysates, we analyzed the aminoglycoside resistance gene content of strains belonging to eight clusters identified by pulsed-field gel electrophoresis. In a single reaction were combined three primer pairs in order to amplify the genes coding for AAC(6')-Ih, AAC(3)-I, and AAC(3)-II, three primer pairs for the genes coding for ANT(2'')-I, APH(3')-VI, and rRNA 16S as internal control, and finally two primer pairs for the genes coding for AAC(6')-Ib and APH(3')-I. According to the aminoglycoside resistance gene patterns, the strains of the eight clusters were distributed into seven classes. This simple and rapid (< 8 h) fingerprinting technique could be a useful tool for the epidemiological investigation of A. baumannii nosocomial infections.

Coordinate involvement of invasin and Yop proteins in a Yersinia pseudotuberculosis-specific class I-restricted cytotoxic T cell-mediated response

Yersinia pseudotuberculosis is a pathogenic enteric bacteria that evades host cellular immune response and resides extracellularly in vivo. Nevertheless, an important contribution of T cells to defense against Yersinia has been previously established. In this study we demonstrate that Lewis rats infected with virulent strains of Y. pseudotuberculosis, mount a Yersinia-specific, RT1-A-restricted, CD8+ T cell-mediated, cytotoxic response. Sensitization of lymphoblast target cells for cytolysis by Yersinia-specific CTLs required their incubation with live Yersinia and was independent of endocytosis. Although fully virulent Yersinia did not invade those cells, they attached to their surface. In contrast, invasin-deficient strain failed to bind to blast targets or to sensitize them for cytolysis. Furthermore, an intact virulence plasmid was an absolute requirement for Yersinia to sensitize blast targets for cytolysis. Using a series of Y. pseudotuberculosis mutants selectively deficient in virulence plasmid-encoded proteins, we found no evidence for a specific role played by YadA, YopH, YpkA, or YopJ in the sensitization process of blast targets. In contrast, mutations suppressing YopB, YopD, or YopE expression abolished the capacity of Yersinia to sensitize blast targets. These results are consistent with a model in which extracellular Yersinia bound to lymphoblast targets via invasin translocate inside eukaryotic cytosol YopE, which is presented in a class I-restricted fashion to CD8+ cytotoxic T cells. This system could represent a more general mechanism by which bacteria harboring a host cell contact-dependent or type III secretion apparatus trigger a class I-restricted CD8+ T cell response.

Nosocomial outbreak of Klebsiella pneumoniae producing SHV-5 extended-spectrum beta-lactamase, originating from a contaminated ultrasonography coupling gel

Klebsiella pneumoniae resistant to ceftazidime was isolated from six adult women and two neonates hospitalized between July and November 1993 in the Department of Obstetrics and Gynecology of Boucicaut Hospital (Paris, France). The epidemiological investigation revealed a notably short delay (less than 48 h) between admission and contamination of the six adults and peripartum transmission to the neonates. The only environmental source of ceftazidime-resistant K. pneumoniae was the ultrasonography coupling gel used in the emergency room. Phenotypic (biotyping and antibiotyping) and genotypic (plasmid profile and pulsed-field gel electrophoresis) analysis of all the clinical isolates indicated the spread of a single strain. It produced SHV-5 and TEM-1 beta-lactamases, as demonstrated by isoelectric focusing and gene sequencing. The risk of cross-contamination in ultrasonography procedures is usually low and had not been associated so far with bacteria producing an extended-spectrum beta-lactamase (ESBL). Furthermore, this is the first time an epidemic of an SHV-5 ESBL-producing member of the family Enterobacteriaceae has been reported from a French hospital.

Molecular characterization of IS1541 insertions in the genome of Yersinia pestis

The genome of Yersinia pestis, the causative agent of plague, contains at least 30 copies of an element, designated IS1541, which is structurally related to IS200 (85% identity). One such element is inserted within the chromosomal inv gene (M. Simonet, B. Riot, N. Fortineau, and P. Berche, Infect. Immun. 64:375-379, 1996). We characterized other IS1541 insertions by cloning 14 different Y. pestis 6/69M loci carrying a single copy of this insertion sequence (IS) into Escherichia coli and, for each element, sequencing 250 bp of both flanking regions. In no case was this IS element inserted into large open reading frames; however, in eight cases, it was detected downstream (17 to 139 bp) of genes thought to be transcribed monocistronically or which constituted the last gene of an operon, and in only one case was it detected upstream (37 bp) of the first gene of an operon. Sequence analysis revealed stem-loop structures (deltaG, < -10 kcal) resembling rho-independent transcription terminators in 8 of the 14 insertion sites. These motifs might constitute hot spots for insertion of this IS1541 element within the Y. pestis genome.

Urease is not involved in the virulence of Yersinia pseudotuberculosis in mice

A chromosomal locus (ure) involved in the production of urease activity in the bacterial pathogen Yersinia pseudotuberculosis was characterized. The genetic organization of the Y. pseudotuberculosis ure locus closely resembles that of the related ureolytic Yersinia species Y. enterocolitica. This locus encompasses seven open reading frames encoding polypeptides with predicted molecular weights of 10,894 (UreA), 15,820 (UreB), 61,001 (UreC), 25,801 (UreE), 24,551 (UreF), 20,330 (UreG), and 31,308 (UreD). The polypeptides have 85 to 96% identity with the corresponding Ure polypeptides of Y. enterocolitica serotype 0:8. Restriction fragment length polymorphisms of the ure loci from 12 unrelated Y. pseudotuberculosis strains produced by HaeIII and MboI indicate a low level of genetic variability of this locus in this species. The role of urease in the pathogenicity of Y. pseudotuberculosis was studied by constructing an isogenic urease-negative mutant obtained by disruption of structural gene ureB by aphA-3', which encodes kanamycin resistance. Experimental infection of mice with this mutant demonstrates that urease is not essential for Y. pseudotuberculosis virulence. Urease might be required mostly during the saprophytic life of this pathogen.

Novel transferable beta-lactam resistance with cephalosporinase characteristics in Salmonella enteritidis

An isolate of Salmonella enteritidis was found to produce a plasmid-encoded beta-lactamase (DHA-1) that conferred resistance to extended-spectrum cephalosporins and cephamycins. The substrate and inhibition profiles of this enzyme resemble a class C beta-lactamase. This is the first report of a plasmid-mediated cephalosporinase of this class in the Salmonella genus.

Molecular typing of Yersinia pseudotuberculosis by using an IS200-like element

The IS200-like insertion sequence (IS) is a 708-bp element recently found in Yersinia pestis. Its nucleotide sequence is 85% identical to that of IS200 recovered in most Salmonella enterica isolates. It is also present in multiple copies in Y. pseudotuberculosis. In contrast, this IS is found in some (biotype 1B strains) but not other Y. enterocolitica strains and is absent in the nonpathogenic yersiniae: Y. frederiksenii, Y. kristensenii, Y. intermedia, Y. bercovieri, and Y. mollaretii. The number and locations of the ISs in the Y. pseudotuberculosis genome vary among strains, resulting in a high degree of polymorphism, but IS fingerprints are stable after multiple subcultures of clinical isolates. The discriminative power of IS typing is better than that of ribotyping and almost as good as that of the time-consuming method of pulsotyping. Overall, IS200-like is a useful molecular marker in determining the epidemiology of Y. pseudotuberculosis infections.

Evaluation of tuberculosis transmission in a community by 1 year of systematic typing of Mycobacterium tuberculosis clinical isolates

Interhuman transmission of Mycobacterium tuberculosis was investigated by using molecular typing, including restriction fragment length polymorphism with probes IS6110, DR (direct repeat) and PGRS (polymorphic GC-rich sequence) and a PCR method using the inverted repeat sequences of IS6110 as primers. From 105 patients hospitalized for tuberculosis during a 1-year survey in three hospitals in Paris, France, 111 isolates were collected and analyzed. Eighty-eight patients were infected with genetically different isolates, demonstrating the clonal heterogeneity of M. tuberculosis in these patients originating from various geographical areas. Fourteen patients were infected by strains clustered with identical fingerprints. An epidemiological relatedness was demonstrated for isolates from only seven of these patients. Thus, the typing of isolates from all tuberculous patients in hospitals during 1 year allows the detection of transmission in the general community. This would improve the case findings, thereby further improving the detection of outbreaks.

Invasin production by Yersinia pestis is abolished by insertion of an IS200-like element within the inv gene

The two enteropathogens Yersinia pseudotuberculosis and Yersinia enterocolitica penetrate eukaryotic cells in vitro through invasin, a surface-exposed protein. In contrast, Yersinia pestis, the causative agent of plague, is unable to enter mammalian cell lines, although the inv gene is present on its chromosome. Although 99.3% identical to the inv gene of Y. pseudotuberculosis, the Y. pestis inv gene was disrupted in its central region by a 708-bp IS200-like element. Multiple copies of this insertion sequence element were found within the genome of the plague bacillus.

Data analysis needs for health sector reform

This paper addresses the role of information in health policy reform. It recognizes that reform can be based on data, but that there are other influences on health policy. The steps involved in making policy, including problem identification, comparison of solutions, policy adoption, implementation, and amendment, all require information. When information is unavailable for any of these steps, the policy process sometimes proceeds without it. The policy makers must make difficult choices regarding the potential benefit of comprehensive information to the policy outcome versus the potential drawbacks, in terms of time and cost, of seeking the missing information. Different areas where data are needed within health policy are enumerated, as are sources of health policy data, and examples of strategies are given. Finally, three case studies are presented, highlighting the use of information in policy making. The National Epidemiology Board in Thailand commissioned studies by experts on relevant policy topics. It had a substantial impact on changing policies in the areas of AIDS control, iodine deficiency, essential drugs and vaccination. The attempt at decentralizing health administration to the province level in Papua New Guinea is the second example presented. At the time of the evaluation, this effort had not yet attained its objectives of improving the health of the people, nor had it reduced costs or lessened inequity among regions. If this reform had been tested in a pilot project, its problems may have been discovered at an earlier stage of implementation when they would have been easier to correct. The final case concerns the UNICEF child survival interventions during the 1980s. These interventions were chosen based on cost-effectiveness analysis and were successfully implemented. The use of cost-effectiveness analysis in prioritizing interventions is one example of the way in which information can improve policy and health outcomes.

[Comparative activity of oral beta-lactam antibiotics against fifty strains of Haemophilus influenzae producing a beta-lactamase according to bacterial inoculum]

Minimal inhibitory concentrations (MICs) of amoxycillin alone and in combination with 2 mg/l or 4 mg/l clavulanic acid, ampicillin alone and in combination with 4 mg/l or 8 mg/l sulbactam, cefuroxime and cefaclor, were determined by the agar dilution method, with bacterial inoculum size ranging from 3 x 10(7) to 3 x 10(9) colony-forming units per ml. As expected, an inoculum effect was observed with cefaclor. In contrast, MICs of amoxycillin in combination with clavulanic acid did not significantly increase with the inoculum size. Ampicillin combined with sulbactam, and cefuroxime were less efficient at the highest bacterial concentration tested.

Investigation of hospital-acquired infections due to Alcaligenes denitrificans subsp. xylosoxydans by DNA restriction fragment length polymorphism

We demonstrate that DNA restriction fragment length polymorphism determined by pulsed-field gel electrophoresis is very useful in the investigation of the epidemiology of hospital-acquired infections caused by Alcaligenes denitrificans subsp. xylosoxydans. This approach showed that hospital-acquired infections caused by this opportunistic pathogen over a 6-month period in 10 patients hospitalized in an intensive care unit and a surgical unit were not a true outbreak. In addition, this molecular typing method established that the respiratory therapy equipment was the source of the contamination of two patients.

Immunization with live aroA recombinant Salmonella typhimurium producing invasin inhibits intestinal translocation of Yersinia pseudotuberculosis

The Yersinia pseudotuberculosis inv gene encodes invasin, a 103-kDa outer membrane protein that allows bacteria to enter mammalian cells. The gene was subcloned into the attenuated aroA mutant of Salmonella typhimurium SL3261. Invasin was produced by the recombinant Salmonella strain and increased the ability of microorganisms to translocate from the intestinal lumen to the mesenteric lymph nodes. Specific antibodies for invasin were detected in sera and intestinal secretions of mice following oral immunization with the live Inv+ Salmonella strain. The immunization strongly inhibited intestinal translocation of Y. pseudotuberculosis when this pathogen was inoculated to mice but failed to prevent Yersinia dissemination from the gut lymphoid tissue.

Lack of antibody response to invasin in humans with yersiniosis

The Yersinia pseudotuberculosis inv gene encodes invasin, a 103-kDa outer membrane protein allowing bacteria to penetrate mammalian cells. This protein is produced in vitro at below 30 degrees C. In this work, we studied the antibody response against invasin in humans suffering from yersiniosis and in mice orally infected with a virulent strain of Y. pseudotuberculosis. Infection with enteropathogenic Yersinia strains did not induce either a systemic or a gut antibody response to invasin. Our results suggest that the inv gene is not expressed in the gut at 37 degrees C and, therefore, that invasin is not present to the immune system when microorganisms multiply in the host tissues.

[Scopulariopsis brevicaulis otomycosis after tympanoplasty]

We report a case of otomycosis due to Scopulariopsis brevicaulis in a patient who has undergone tympanoplasty 3 months before. Mycological finding led us to consider this fungus as the causative agent. Whereas in vitro studies show a better efficiency of azole derivatives, cure was obtained with nystatine after two treatment failures in our patient.

Coryneform bacteria isolated from middle ear fluid

Nineteen strains of facultatively anaerobic gram-positive rods isolated in pure culture from middle ear fluids were identified. All effusions were collected by tympanocentesis in children with acute otitis media. Identification of microorganisms to the genus level was done by studying the cell wall composition. Sixteen strains contain meso-diaminopimelic acid and arabinogalactan polymer but lack mycolic acids; therefore, these strains do not belong to a previously described taxon. Because of similarities with Corynebacterium afermentans (Centers for Disease Control group ANF-1), we temporarily classified these mycolateless strains ANF-1 like. Isolation of these microorganisms in pure culture from middle ear fluids collected by tympanocentesis is a strong argument for their involvement in acute otitis media.

[Bacterial epidemiology of acute otitis media]

Since the middle of the 1980's, Haemophilus influenzae is the most common bacterial species responsible for acute otitis media in France, followed by Streptococcus pneumoniae. Haemophilus influenzae has maintained its leading position since 1985, but the rate of pneumococcal acute otitis media is increasing fairly steadily. The other recent change with regard to the distribution of bacterial agents is the emergence, four years later than in North America, of Branhamella catarrhalis which currently accounts for 10% of cases of acute otitis media. Modifications in the behavior of microorganisms in relation to antimicrobials usually given to treat upper respiratory tract infections have occurred. Staphylococcus aureus and Branhamella catarrhalis have always exhibited marked resistance to ampicillin due to the production of beta-lactamases. Resistance of Haemophilus influenzae to ampicillin has been increasing gradually since 1985, again with a lag of a few years as compared with the United States; at present, this form of resistance is seen in approximately 35% of strains. More recently in France, 20% of pneumococcal strains recovered from middle ear pus have been shown to have abnormal susceptibility to penicillin. These changes in the behavior of the two main pathogens, i.e., Haemophilus influenzae and Streptococcus pneumoniae, require implementation of rigorous multiregional epidemiologic surveillance programs and may justify reappraisal of current therapeutic approaches.