We describe the first clinical isolate of Bordetella petrii from a patient with mandibular osteomyelitis. The only previously documented isolation of B. petrii occurred after the initial culture of a single strain from an environmental source. (+info)
Phg, a novel member of the autotransporter family present in Bordetella species.
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Several proteins encoded in the genomes of Bordetella species show significant sequence similarity to the autotransporter domains of surface exposed or secreted virulence factors of bordetellae such as pertactin, tracheal colonization factor or Vag8. One of these putative autotransporters, provisionally termed Phg, is encoded by the pertactin homologous gene (phg), which is highly conserved in Bordetella pertussis, B. bronchiseptica and B. parapertussis, but absent in B. avium and B. petrii. In contrast to homologues with documented functions in host interaction and virulence, several key amino acids probably involved in proteolytic processing of the autotransporter domain are not conserved in Phg. The transcription start site of phg was identified by primer extension analysis, but differential transcription of phg could not be detected in B. bronchiseptica strains under conditions that lead to enhanced expression of other known Bordetella autotransporter proteins. A mutant of B. pertussis was constructed in which major parts of phg are substituted by a kanamycin resistance cassette. Virulence testing of this mutant in a mouse respiratory infection model showed the same colonization properties as the wild-type strain. (+info)
Adenylate cyclase toxin (ACT) from Bordetella hinzii: characterization and differences from ACT of Bordetella pertussis.
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Bordetella hinzii is a commensal respiratory microorganism in poultry but is increasingly being recognized as an opportunistic pathogen in immunocompromised humans. Although associated with a variety of disease states, practically nothing is known about the mechanisms employed by this bacterium. In this study, we show by DNA sequencing and reverse transcription-PCR that both commensal and clinical strains of B. hinzii possess and transcriptionally express cyaA, the gene encoding adenylate cyclase toxin (ACT) in other pathogenic Bordetella species. By Western blotting, we also found that B. hinzii produces full-length ACT protein in quantities that are comparable to those made by B. pertussis. In contrast to B. pertussis ACT, however, ACT from B. hinzii is less extractable from whole bacteria, nonhemolytic, has a 50-fold reduction in adenylate cyclase activity, and is unable to elevate cyclic AMP levels in host macrophages (nontoxic). The decrease in enzymatic activity is attributable, at least in part, to a decreased binding affinity of B. hinzii ACT for calmodulin, the eukaryotic activator of B. pertussis ACT. In addition, we demonstrate that the lack of intoxication by B. hinzii ACT may be due to the absence of expression of cyaC, the gene encoding the accessory protein required for the acylation of B. pertussis ACT. These results demonstrate the expression of ACT by B. hinzii and represent the first characterization of a potential virulence factor of this organism. (+info)
Stable coexistence of five bacterial strains as a cellulose-degrading community.
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A cellulose-degrading defined mixed culture (designated SF356) consisting of five bacterial strains (Clostridium straminisolvens CSK1, Clostridium sp. strain FG4, Pseudoxanthomonas sp. strain M1-3, Brevibacillus sp. strain M1-5, and Bordetella sp. strain M1-6) exhibited both functional and structural stability; namely, no change in cellulose-degrading efficiency was observed, and all members stably coexisted through 20 subcultures. In order to investigate the mechanisms responsible for the observed stability, "knockout communities" in which one of the members was eliminated from SF356 were constructed. The dynamics of the community structure and the cellulose degradation profiles of these mixed cultures were determined in order to evaluate the roles played by each eliminated member in situ and its impact on the other members of the community. Integration of each result gave the following estimates of the bacterial relationships. Synergistic relationships between an anaerobic cellulolytic bacterium (C. straminisolvens CSK1) and two strains of aerobic bacteria (Pseudoxanthomonas sp. strain M1-3 and Brevibacillus sp. strain M1-5) were observed; the aerobes introduced anaerobic conditions, and C. straminisolvens CSK1 supplied metabolites (acetate and glucose). In addition, there were negative relationships, such as the inhibition of cellulose degradation by producing excess amounts of acetic acid by Clostridium sp. strain FG4, and growth suppression of Bordetella sp. strain M1-6 by Brevibacillus sp. strain M1-5. The balance of the various types of relationships (both positive and negative) is thus considered to be essential for the stable coexistence of the members of this mixed culture. (+info)
Bordetella filamentous hemagglutinin plays a critical role in immunomodulation, suggesting a mechanism for host specificity.
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Bordetella pertussis, the causative agent of the acute childhood respiratory disease whooping cough, is a human-adapted variant of Bordetella bronchiseptica, which displays a broad host range and typically causes chronic, asymptomatic infections. These pathogens express a similar but not identical surface-exposed and secreted protein called filamentous hemagglutinin (FHA) that has been proposed to function as both a primary adhesin and an immunomodulator. To test the hypothesis that FHA plays an important role in determining host specificity and/or the propensity to cause acute versus chronic disease, we constructed a B. bronchiseptica strain expressing FHA from B. pertussis (FHA(Bp)) and compared it with wild-type B. bronchiseptica in several natural-host infection models. FHA(Bp) was able to substitute for FHA from B. bronchiseptica (FHA(Bb)) with regard to its ability to mediate adherence to several epithelial and macrophage-like cell lines in vitro, but it was unable to substitute for FHA(Bb) in vivo. Specifically, FHA(Bb), but not FHA(Bp), allowed B. bronchiseptica to colonize the lower respiratory tracts of rats, to modulate the inflammatory response in the lungs of immunocompetent mice, resulting in decreased lung damage and increased bacterial persistence, to induce a robust anti-Bordetella antibody response in these immunocompetent mice, and to overcome innate immunity and cause a lethal infection in immunodeficient mice. These results indicate a critical role for FHA in B. bronchiseptica-mediated immunomodulation, and they suggest a role for FHA in host specificity. (+info)
Evaluation of real-time PCR for diagnosis of Bordetella pertussis infection.
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BACKGROUND: Nucleic acid amplification of the IS481 region by PCR is more sensitive than culture for detection and diagnosis of Bordetella pertussis but the assay has known cross-reactivity for Bordetella holmesii and its use as a routine diagnostic assay has not been widely evaluated. METHODS: The objectives of this study were: 1) to assess the diagnostic utility of real-time IS481 PCR by comparison of results with culture and direct fluorescent antigen (DFA) testing for B. pertussis, 2) to employ a PCR assay designed against a different insertion sequence (IS1001) to assess the incidence of B. holmesii in symptomatic individuals and 3) to design and evaluate a new PCR-based assay which could be used for B. pertussis confirmation. A total of 808 nasopharyngeal specimens were included in the study the majority of which were submitted in charcoal transport medium (88%) with the rest submitted in Regan-Lowe medium. RESULTS: Concordant results for PCR, DFA and culture were obtained for 21 B. pertussis positive and 729 B. pertussis negative specimens. DFA was prone to false positive and negative reactions when compared with both PCR and culture. The IS481 PCR identified 28 positive results for specimens that were DFA and culture negative. A novel real-time PCR targeting the B. pertussis toxin promoter was found to be specific and useful for confirming the majority of IS481 positive specimens as B. pertussis. B. holmesii was not detected in any of the submitted samples. CONCLUSION: The potential pick up of B. holmesii by the IS481 PCR had minimal diagnostic relevance in the Alberta population during the time period of our study. The IS481 PCR assay is now used in our laboratory routinely for front-line screening of samples for B. pertussis with associated enhancement in diagnostic sensitivity compared with DFA and culture. Retrospectively, patients' samples are batched and tested by the IS1001 MB and TPR assays for research purposes and to ensure there is no change in B. holmesii incidence in the population. (+info)
Development and evaluation of a loop-mediated isothermal amplification method for rapid diagnosis of Bordetella pertussis infection.
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We developed a loop-mediated isothermal amplification (LAMP) method to detect Bordetella pertussis infection. This LAMP assay detected B. pertussis with high sensitivity, but not other Bordetella species. Among nasopharyngeal swab samples from subjects with suspected pertussis, LAMP results showed a high level of agreement with results of conventional PCR. This method is a rapid, sensitive, and specific method for diagnosis of B. pertussis infection even in clinical laboratories with no specific equipment. (+info)
Bacteriophage-mediated competition in Bordetella bacteria.
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Apparent competition between species is believed to be one of the principal driving forces that structure ecological communities, although the precise mechanisms have yet to be characterized. Here we develop a model system that isolates phage-mediated interactions by neutralizing resource competition with a large excess of nutrients, and consists of two genetically identical Bordetella strains that differ only in that one is the carrier of phage and the other is susceptible to the phage. We observe and quantify the competitive advantage of the bacterial strain bearing the prophage in both invading and in resisting invasion by the bacterial strain sensitive to the phage, and use our experimental measurements to develop a mathematical model of phage-mediated competition. The model predicts, and experimental evidence confirms, that the competitive advantage conferred by the lysogenic phage depends only on the phage pathology on the sensitive bacterial strain and is independent of other phage and host parameters, such as the infection-causing contact rate, the spontaneous and infection-induced lysis rates and the phage burst size. This work combines experimental and mathematical approaches to the study of phage-driven competition, and provides an experimentally tested framework for evaluation of the effects of pathogens/parasites on interspecific competition. (+info)