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Susceptibility of various animals to the vesiculovirus Piry.

To determine the pathogenic potential of the vesiculovirus Piry for domestic animals, two ponies, two steers, three sheep, three goats and three pigs were inoculated intradermally in the tongue or, in the case of the pigs, in the snout, heel and coronary band. Inoculated animals were housed in one room and allowed to mingle freely with an equal number of uninoculated contact animals of each species. Clinical signs of infection, consisting of elevated temperature and ulcers at the inoculation sites, were only observed in the ponies, but all inoculated animals developed specific antibody following inoculation. In addition, one of the contact sheep had neutralizing antibody to Piry at 7 and 29 days post inoculation suggesting a contact infection. Virus was not demonstrated in tissues, other than tongue, of any animal. The failure of Piry virus to produce lesions in steers, sheep, goats and pigs and only limited ulcerations in ponies suggests that this virus is not similar pathogenically to New Jersey and Indiana strains of vesiculoviruses which produce classical vesicular stomatitis. Lethal infections were produced by inoculation into suckling mice and hamsters, adult hamsters and embryonating chicken eggs. Further, lethal infections followed contact of adult female hamsters with their inoculated litters.

Animals↗

Monoclonal anti-annexin V antibody inhibits trophoblast gonadotropin secretion and induces syncytiotrophoblast apoptosis.

The pathogenic role of anti-annexin V antibodies remains unclear. Anti-annexin V antibodies are frequently associated with higher incidences of intrauterine fetal loss, preeclampsia, and arterial and venous thrombosis. The present study investigated the in vitro ability of anti-annexin V antibody to bind human trophoblast cells, to affect trophoblast gonadotropin secretion and invasiveness, and to induce placental apoptosis. Cytotrophoblast cells were dispersed in Ringer bicarbonate buffer containing trypsin and DNase I, filtered, and layered over a Percoll gradient in Hanks balanced salt solution. In the case of monoclonal anti-annexin V antibody, the highest binding was found when the cells displayed the greatest amount of syncytium formation. Anti-annexin V antibody, but not its negative control, induced trophoblast apoptosis and significantly reduced trophoblast gonadotropin secretion. These findings suggest that recognition by anti-annexin V antibody of adhered annexin V on trophoblast cell structures might represent a potential pathogenic mechanism by which these antibodies can cause defective placentation.

Annexin A5↗

Population structure of Streptococcus agalactiae reveals an association between specific evolutionary lineages and putative virulence factors but not disease.

To evaluate the genetic diversity and relationships in a collection of 85 Danish strains of Streptococcus agalactiae (group B streptococcus) we have performed restriction fragment length polymorphism analysis on EcoRI- and MspI-digested whole-cell DNA using as probes rRNA, DNA fragments representing the genes encoding hyaluronidase, C5a-peptidase, alpha-antigen, and beta-antigen as well as two randomly selected genomic DNA fragments for which the coding potential is unknown. In addition, we have assayed for expression of hyaluronidase activity and beta-antigen. Combined analyses of our data and those previously obtained by multilocus enzyme electrophoresis and serotyping revealed a population separating into six major lineages that correlate with individual serotypes. The significant linkage disequilibrium of alleles indicates that the S. agalactiae population examined is predominantly clonal. Notably, strains expressing the serotype III capsule divide into two distant evolutionary lineages, of which one lacks expression of hyaluronidase activity. Six North American isolates of serotype III clustered together with multiple Danish serotype III strains, showing that the combinations of characters on which the phylogenetic tree was based are conserved worldwide. Occurrence of beta-antigen correlated with a specific version of the alpha-antigen gene and was exclusively associated with a single major phylogenetic lineage. Comparisons with the clinical history of the strains revealed no evidence of differences in pathogenic potential among the six major genetic divisions.

Adhesins, Bacterial↗

Aerococcus urinae in urinary tract infections.

Aerococcus urinae is a rarely reported pathogen, possibly due to difficulties in the identification of the organism. A. urinae is a gram-positive coccus that grows in pairs and clusters, produces alpha-hemolysis on blood agar, and is negative for catalase and pyrrolidonyl aminopeptidase. Some of these characteristics and its being absent from the databases of most commercial identification systems could allow A. urinae to be misidentified as a streptococcus, enterococcus, or staphylococcus. We report two cases of urinary tract infection (UTI) caused by A. urinae and characterize these isolates by morphology, biochemical testing, whole-cell fatty acid analysis, 16S rRNA gene sequencing, and antibiotic susceptibilities. Most patients infected with A. urinae are elderly males with predisposing conditions who present initially with UTI. Because A. urinae is resistant to sulfonamides, treatment could be inappropriate, with infections resulting in serious complications, including death. It is important for the clinician and the microbiologist to consider A. urinae a potential pathogen and proceed with thorough microbiological identification.

Aged↗

The role of black-pigmented Bacteroides in human oral infections.

Today, 10 black-pigmented Bacteroides (BPB) species are recognized. The majority of these species can be isolated from the oral cavity. BPB species are involved in anaerobic infections of oral and non-oral sites. In the oral cavity, BPB species are associated with gingivitis, periodontitis, endodontal infections and odontogenic abscesses. Cultural studies suggest a specific role of the various BPB species in the different types of infection. Bacteroides gingivalis is closely correlated with destructive periodontitis in adults as well as in juveniles. Bacteroides intermedius seems to be less specific since it is found in gingivitis, periodontitis, endodontal infections and odontogenic abscesses. The recently described Bacteroides endodontalis is closely associated with endodontal infections and odontogenic abscesses of endodontal origin. There are indications that these periodontopathic BPB species are only present in the oral cavity of subjects suffering from periodontal breakdown, being absent on the mucosal surfaces of subjects without periodontal breakdown. BPB species associated with healthy oral conditions are Bacteroides melaninogenicus, Bacteroides denticola and Bacteroides loescheii. There are indications that these BPB species are part of the normal indigenous oral microflora. Many studies in the past have documented the pathogenic potential and virulence of BPB species. This virulence can be explained by the large numbers of virulence factors demonstrated in this group of micro-organisms. Among others, the proteolytic activity seems to be one of the most important features. Several artificial substrates as well as numerous biological proteins are degraded. These include anti-inflammatory proteins such as alpha-2-macroglobulin, alpha-1-antitrypsin, C3 and C5 complement factors and immunoglobulins. B. gingivalis is by far the most proteolytic species, followed by B. endodontalis. Like other bacteria, the lipopolysaccharide of B. gingivalis has shown to be active in bone resorption in vitro and is capable in stimulating interleukin-1 production in human peripheral monocytes. Based on the well documented association with periodontal disease and the possession of relevant virulence factors, BPB species must be considered as important micro-organisms in the etiology of oral infections. B. gingivalis seems to be the most pathogenic and virulent species.

Bacteroides↗

Eikenella corrodens: an unusual cause of severe parapneumonic infection and empyema in immunocompetent patients.

Over the past 25 years, Eikenella corrodens has increasingly been recognized for its pathogenic potential. Previously identified as an organism most likely to cause opportunistic infection in the immunocompromised host, Eikenella more recently has been implicated in a number of clinical infections in non-immunocompromised patients. We report a case of community-acquired pneumonia, caused by Eikenella, in a patient with diabetes mellitus and a past history of testicular cancer. A review of the literature was conducted in order to review other cases of pulmonary infection with Eikenella, in immunocompetent adults. The condition was diagnosed in 15 patients, occurring most often in men with a mean age of 50. Patients most often presented with fever, cough and pleuritic chest pain. Complications often involved parapneumonic effusion, empyema, and necrotic parenchymal disease. Mortality rates appear to be low. Eikenella is most often susceptible to ampicillin and has variable susceptibility to aminoglycosides. The addition of clindamycin in non-immunocompromised patients with Eikenella infection, co-infected with other pathogens, also appears to be useful. Surgical intervention plays an important role in the recovery of these patients.

Adult↗

Key virulence factors responsible for differences in pathogenicity between clinically proven live-attenuated Japanese encephalitis vaccine SA14-14-2 and its pre-attenuated highly virulent parent SA14.

Japanese encephalitis virus (JEV), a neuroinvasive and neurovirulent orthoflavivirus, can be prevented in humans with the SA14-14-2 vaccine, a live-attenuated version derived from the wild-type SA14 strain. To determine the viral factors responsible for the differences in pathogenicity between SA14 and SA14-14-2, we initially established a reverse genetics system that includes a pair of full-length infectious cDNAs for both strains. Using this cDNA pair, we then systematically exchanged genomic regions between SA14 and SA14-14-2 to generate 20 chimeric viruses and evaluated their replication capability in cell culture and their pathogenic potential in mice. Our findings revealed the following: (i) The single envelope (E) protein of SA14-14-2, which contains nine mutations (eight in the ectodomain and one in the stem region), is both necessary and sufficient to render SA14 non-neuroinvasive and non-neurovirulent. (ii) Conversely, the E protein of SA14 alone is necessary for SA14-14-2 to become highly neurovirulent, but it is not sufficient to make it highly neuroinvasive. (iii) The limited neuroinvasiveness of an SA14-14-2 derivative that contains the E gene of SA14 significantly increases (approaching that of the wild-type strain) when two viral nonstructural proteins are replaced by their counterparts from SA14: (a) NS1/1', which has four mutations on the external surface of the core β-ladder domain; and (b) NS2A, which has two mutations in the N-terminal region, including two non-transmembrane α-helices. In line with their roles in viral pathogenicity, the E, NS1/1', and NS2A genes all contribute to the enhanced spread of the virus in cell culture. Collectively, our data reveal for the first time that the E protein of JEV has a dual function: It is the master regulator of viral neurovirulence and also the primary initiator of viral neuroinvasion. After the initial E-mediated neuroinvasion, the NS1/1' and NS2A proteins act as secondary promoters, further amplifying viral neuroinvasiveness.

Animals↗

Diffusely adhering Escherichia coli strains induce attaching and effacing phenotypes and secrete homologs of Esp proteins.

Recent epidemiological studies indicate that Escherichia coli strains which exhibit the diffuse-adherence phenotype (DAEC strains) represent a potential cause of diarrhea in infants. We investigated the interaction of DAEC strains isolated from diarrhea patients in Brazil and in Germany with epithelial cells in tissue culture. The investigated strains were identified as DAEC strains by (i) their attachment pattern, (ii) presence of genes associated with the Dr family of adhesins, and (iii) lack of genetic markers for other diarrhea-associated E. coli categories. Several clinical DAEC isolates were shown to secrete similar patterns of proteins into tissue culture medium. Protein secretion was found to be regulated by environmental parameters, namely, medium, temperature, pH, and iron concentration. DAEC strains secreting these proteins induced accumulation of actin and tyrosine-phosphorylated proteins at sites of bacterial attachment, leading to the formation of pedestals and/or extended surface structures. These changes were phenotypically similar to the attaching and effacing (A/E) lesions observed with enteropathogenic and some enterohemorrhagic E. coli strains carrying the locus of enterocyte effacement (LEE) pathogenicity island. Proteins homologous to the EspA, EspB, and EspD proteins, necessary for signal transduction events inducing A/E lesions, were identified by sequence analysis and cross-reaction of specific antibodies. However, initially nonadhering strains secreting these proteins induced signal transduction events only after prolonged infection. These results indicate that secretion of the Esp proteins alone is not sufficient for efficient signal transduction. This study further shows that some DAEC strains are likely to contain a homolog(s) of the LEE locus which may contribute to the pathogenic potential of DAEC.

Actins↗

Cytotoxin testing of environmental Aeromonas spp. in Vero cell culture.

BACKGROUND & OBJECTIVES: Aeromonas spp. are known to cause a variety of infections in humans and this organism has been isolated from a variety of sources including environmental sources. The pathogenicity of the environmental isolates in and around Vellore has not been studied. This study was conducted to determine the cytotoxicity of the Aeromonas spp. isolated from water bodies, soil sediments, plankton and sewers in and around Vellore. METHODS: Aeromonas spp. isolated from environmental sources were identified by standard procedures. Representative isolates of Aeromonas spp. were tested for cell free cytotoxic factor in tissue culture system. Undiluted and diluted cell free filtrates of isolates and known toxigenic and non-toxigenic bacteria were added to Vero cell monolayer in microtitre plates. After appropriate incubation in 5 per cent CO2 atmosphere, the microtitre plate was examined for cytopathic effect. Cell detachment and shrinkage of Vero cells were recorded as toxic changes. RESULTS: All 36 environmental isolates demonstrated cytopathic effect of which 41.7, 50 and 8.3 per cent belonged to A. hydrophila, A. veronii biotype sobria and A. caviae respectively. INTERPRETATION & CONCLUSION: The results demonstrated the presence of potentially pathogenic environmental aeromonads in and around Vellore and they produced cytotoxin.

Aeromonas↗

B cells are anergic in transgenic mice that express IgM anti-DNA antibodies.

B lymphocytes in individuals with systemic lupus erythematosus (SLE) secrete pathogenic autoantibodies to DNA which cause clinical nephritis. (NZB X NZW) F1 (BW) female mice also secrete pathogenic anti-DNA autoantibodies, and therefore are considered to be an animal model of SLE. The rearranged immunoglobulin (Ig) genes that encode an anti-DNA antibody from a diseased BW mouse have been cloned, and transgenic (Tg) mice have been created by microinjection of these constructs into fertilized eggs from normal mice. As we reported previously, when the construct contains the C gamma 2a heavy chain constant (CH) region, the mice spontaneously secrete anti-DNA IgG and they develop mild nephritis. This demonstrated that the Ig encoded by the transgene is pathogenic. In contrast, here we report that when the construct contains the same anti-DNA Ig variable (V) regions used previously, along with the C mu region, the autoreactive B cells are rendered tolerant. Most B cells in the Tg mice express the mu transgene product on their surface, and rearrangement of endogenous light chain genes is partially suppressed. Furthermore, most hybridomas made from Tg B cells secrete IgM anti-DNA. Despite this, the Tg mice have reduced levels of total serum Ig and they do not secrete anti-DNA IgM either spontaneously or following immunization with DNA. We conclude that most B cells in the Tg mice have been rendered anergic. Anergy is however reversible in vitro; lipopolysaccharide stimulation of Tg B cells leads to the production of a significant amount of IgM anti-DNA antibody. The studies demonstrate that in this line of Tg mice on a normal mouse genetic background potentially pathogenic B cells that express a high-affinity Ig specific for a natural autoantigen are subject to tolerance by induction of anergy.

Animals↗

Antineutrophil cytoplasmic autoantibodies and pathophysiology: new insights from animal models.

PURPOSE OF REVIEW: Since the discovery of antineutrophil cytoplasmic autoantibodies (ANCA) and their association with the occurrence of several types of small-vessel vasculitis, a causal relation between the two has been suggested. Various in vitro and in vivo experimental data provide indirect evidence in support of this view. This article comprises a review of the animal models that have been used to investigate the pathogenesis of ANCA-associated vasculitis, and focuses on recent developments in this field. RECENT FINDINGS: Xiao et al. provide definite proof of the pathogenic potential of ANCA in a novel mouse model of myeloperoxidase (MPO)-ANCA-associated vasculitis, in which transfer of splenocytes or IgG from MPO-/- mice immunized with murine MPO, to naive wild-type or Rag2-/- (lacking mature B and T lymphocytes) mice causes a disease remarkably similar to its human counterpart. In addition, preliminary studies by Smyth et al. show that immunization of Wistar Kyoto rats with human MPO induces antihuman MPO antibodies that cross-react with rat MPO, as well as a disease closely resembling human small-vessel vasculitis. Another murine ANCA model is the SCG/Kj mouse. A recent publication by Neumann et al., however, puts an important limitation on the use of this mouse model for the study of ANCA-associated vasculitis, demonstrating multiple immune complex deposits in the spontaneously occurring vascular lesions. SUMMARY Recently developed animal models of MPO-ANCA-associated vasculitis convincingly demonstrate that MPO-ANCA are pathogenic. Whether similar strategies can be used to develop an appropriate model for proteinase 3-ANCA-associated vasculitis remains to be investigated.

Animals↗

Helicobacter bilis-induced inflammatory bowel disease in scid mice with defined flora.

Helicobacter bilis has been isolated from aged inbred mice with multifocal chronic hepatitis and from scid mice with diarrhea, proliferative typhlitis, and colitis. To determine the pathogenic potential of H. bilis, we inoculated 4-week-old female Tac:Icr:Ha(ICR)-scidfDF mice by intraperitoneal injection of approximately 10(8) CFU of H. bilis in phosphate-buffered saline (PBS) (n = 15) or PBS alone (n = 10) and necropsied them at 7 weeks postinfection. Sham-inoculated mice had no significant gross or histopathological findings. In contrast, all 15 experimentally inoculated mice (confirmed to be H. bilis-colonized by culture and PCR of cecal contents) exhibited varying degrees of inflammatory bowel disease (IBD). Proliferative typhlocolitis was characterized by focal to segmental areas of crypt hyperplasia and a predominantly histiocytic inflammatory cell infiltrate. Labeling indices for 5-bromo-2'-deoxyuridine incorporation were increased approximately 2.5-fold in the ceca and colons of H. bilis-inoculated mice. This is the first study to demonstrate experimentally that infection with H. bilis causes IBD in scid mice with defined flora. This result both confirms a pathogenic role for H. bilis in mice and provides a new model relating a specific microbial agent and IBD.

Animals↗

Antimicrobial proteins and polypeptides in pulmonary innate defence.

Inspired air contains a myriad of potential pathogens, pollutants and inflammatory stimuli. In the normal lung, these pathogens are rarely problematic. This is because the epithelial lining fluid in the lung is rich in many innate immunity proteins and peptides that provide a powerful anti-microbial screen. These defensive proteins have anti-bacterial, anti- viral and in some cases, even anti-fungal properties. Their antimicrobial effects are as diverse as inhibition of biofilm formation and prevention of viral replication. The innate immunity proteins and peptides also play key immunomodulatory roles. They are involved in many key processes such as opsonisation facilitating phagocytosis of bacteria and viruses by macrophages and monocytes. They act as important mediators in inflammatory pathways and are capable of binding bacterial endotoxins and CPG motifs. They can also influence expression of adhesion molecules as well as acting as powerful anti-oxidants and anti-proteases. Exciting new antimicrobial and immunomodulatory functions are being elucidated for existing proteins that were previously thought to be of lesser importance. The potential therapeutic applications of these proteins and peptides in combating infection and preventing inflammation are the subject of ongoing research that holds much promise for the future.

Animals↗

Experimental infection of broiler breeder hens with the intestinal spirochaete Brachyspira (Serpulina) pilosicoli causes reduced egg production.

The pathogenic potential of the anaerobic intestinal spirochaetes Brachyspira (Serpulina) pilosicoli and Brachyspira innocens was evaluated in adult chickens. Thirty 17-week-old Cobb broiler breeder hens were individually caged in three groups of 10 birds. Control birds (group A) were sham inoculated with sterile broth medium. Birds in the other two groups (groups B and C) were inoculated, respectively, with an isolate of B. innocens or of B. pilosicoli. Birds were monitored daily, and killed at 41 weeks of age. Infection had no consistent effect on body weight gain, but inoculation with B. pilosicoli resulted in a transient increase in faecal water content. B. innocens infection had no effect on egg production, but B. pilosicoli infection caused a delayed onset of laying, and a highly significant reduction in egg production over the first 11 weeks of lay. This study confirms that B. pilosicoli can cause serious egg production losses in adult chickens, while B. innocens is not obviously pathogenic.

Animals↗

Burkholderia pseudomallei: another emerging pathogen in cystic fibrosis.

BACKGROUND: Burkholderia pseudomallei is an important cause of acute fulminant pneumonia and septicaemia in tropical regions of northern Australia and south east Asia. Subacute and chronic forms of the disease also occur. There have been three recent reports of adults with cystic fibrosis (CF) who presumably acquired B pseudomallei infection during extended vacations or residence in either Thailand or northern Australia. METHODS: The clinical course, molecular characteristics, serology and response to treatment are described in four adult CF patients infected with B pseudomallei. Polymerase chain reaction (PCR) based methods were used to confirm B pseudomallei and exclude B cepacia complex. Genotyping was performed using randomly amplified polymorphic DNA (RAPD) PCR and pulsed field gel electrophoresis (PFGE). RESULTS: Four patients are described with a mean duration of infection of 32 months. All but one patient lived in tropical Queensland. Two patients (with the longest duration of infection) deteriorated clinically and one subsequently died of respiratory failure. Both responded to intravenous treatment specifically targeting B pseudomallei. Another patient suffered two severe episodes of acute bronchopneumonia following acquisition of B pseudomallei. Eradication of the organism was not possible in any of the cases. PFGE of a sample isolate from each patient revealed the strains to be unique and RAPD analysis showed retention of the same strain within an individual over time. CONCLUSIONS: These findings support a potential pathogenic role for B pseudomallei in CF lung disease, producing both chronic infection and possibly acute bronchopneumonia. Identical isolates are retained over time and are unique, consistent with likely environmental acquisition and not person to person spread. B pseudomallei is emerging as a significant pathogen for patients with CF residing and holidaying in the tropics.

Adolescent↗

In-vitro Biological Study to Evaluate the Toxic Potentials of Fibrous Materials.

The potential toxicities of fibrous materials were investigated by measuring the levels of cytokines as well as cytoplasmic and lysosomal enzymes released from alveolar macrophages (AMs) in vitro. Five man-made mineral fibers (ceramic, glass, potassium octatitanate, and two magnesium sulfate whiskers), as well as five natural mineral fibers (UICC chrysotile, crocidolite, amosite, anthophylite, and Turkish erionite) were tested. Basic fiber characteristics, including fiber size, surface area, number, and solubility, were also measured. Tumor necrosis factor (TNF) production, lactate dehydrogenase (LDH) and beta-glucuronidase (BGU) release from AMs exposed to potassium octatitanate, magnesium sulfate whiskers, and ceramic fiber correlated with pathologic changes in the lung according to inhalation studies. The solubility of the man-made mineral fibers also correlated with the half-life of clearance in an in-vivo study. The results suggest that measured values of TNF production, LDH and BGU release in vitro, and fiber solubility combined are a good indicator of the pathogenic potential of fibers in vivo.

Journal Article↗

[3 new cases of Enterobacter taylorae infection].

BACKGROUND: Enterobacter taylorae is a recently identified microorganism pertaining to the enterobacterian family. To date few infections by this organism have been reported with their clinical significance being unknown. Three patients with Enterobacter taylorae infection are described with the possible pathogenic capacity of this microorganism in concurrence with opportune epidemiologic features being commented upon in addition to the different sources of infection. METHODS: Biochemical identification of the microorganisms was performed by the automatized MicroScan system (Baxter). The sensitivity to the different antimicrobians was determined by automatized reading (Baxter) of the seried microdilution to the last point. RESULTS: The two first patients presented infection of an open wound with E. taylorae being isolated from the culture of the exudate of the wound and from a culture of the drainage point, respectively. The third patient developed nosocomial bacteremia following prolonged hospital stay with growth of E. taylorae being found in two different blood culture series. Different biotypes of the E. taylorae species were isolated in the three patients. Specific treatment was administered to the three patients according to the antibiogram with improvement in the clinical manifestations being observed. CONCLUSIONS: The three clinical cases herewith described suggest that E. taylorae is a potentially pathogenic microorganism which, in determined circumstances (empiric antibiotic treatment, open wounds, diagnostic or therapeutic instruments) may produce clinical pictures similar to those described for other Enterobacter species.

Aged↗

Lactobacilli and bacteremia in southern Finland, 1989-1992.

In order to assess the potential of lactobacilli to cause serious infections, we studied the prevalence of bacteremia due to Lactobacillus species during a 4-year period (1989-1992) in southern Finland, which has a population of about 2.5 million. Among 3,317 blood culture isolates, lactobacilli were identified in eight patients, five of whom had a severe disease predisposing to bacteremic complications. The eight strains isolated were identified to the species level and typed by carbohydrate fermentation tests and by direct sequencing of enzymatically amplified 16S rRNA. The results did not provide evidence that any particular species or subspecies of Lactobacillus was the cause of the infections; no infections caused by isolates similar to the recently introduced dairy probiotic strain, Lactobacillus GG (ATCC 53103), were observed. The data show an infrequent association of lactobacilli with bacteremic infections in spite of the ubiquitous presence of these organisms in the gastrointestinal tract and their widespread consumption in fermented milks; thus, there is strong evidence that their pathogenic potential is very low.

Adult↗