Bordetella bronchiseptica PagP is a Bvg-regulated lipid A palmitoyl transferase that is required for persistent colonization of the mouse respiratory tract

Bordetella bronchiseptica lipopolysaccharide (LPS) expression varies depending on growth conditions, regulated by the Bvg system. A B. bronchiseptica pagP homologue was identified that is required for Bvg-mediated modification of the lipid A core region of LPS that occurs on switching from the Bvg- to the Bvg+ phase. Structural analysis demonstrated that the lipid A of a B. bronchiseptica pagP mutant differed from wild-type lipid A by the absence of a palmitate group in secondary acylation at the C3' position. The putative pagP promoter drove the expression of a green fluorescent protein (GFP) reporter gene in a Bvg-regulated fashion. These data suggest that B. bronchiseptica pagP encodes a Bvg-regulated lipid A palmitoyl transferase that mediates modification of the lipid A as part of the overall Bvg-mediated adaptation of this organism to changing environmental conditions. We also show that pagP is not required for the initial colonization of the mouse respiratory tract by B. bronchiseptica, but is required for persistence of the organism within this organ.     

Fungal colonization in patients with cancer of the upper respiratory tract

Fungal opportunistic infections are a danger for immunocompromised hosts, such as patients with malignancies, especially in a hospital environment. We studied a group of patients with solid tumors of the respiratory tract on admission and after twenty days of hospitalization. Colonization by moulds and/or yeasts was frequently found.Preventive measures should be applied to avoid colonization inside the hospital. The importance of overcrowding, sanitation and diet is pointed out.     

In vivo colonization profile study of Bordetella bronchiseptica in the nasal cavity

Bordetella bronchiseptica chronically infects a wide range of mammals, and resides primarily in the nasal cavity of the infected host. Multiple virulence factors of Bordetella species have been studied in the context of lower respiratory tract infections, but relatively less is known about the bacterial life cycle in the nasal cavity. Evidences were discovered for Bvg intermediate (Bvg(i)) phase expression in vivo and that the major adhesin filamentous hemagglutinin plays a major role in the colonization of B. bronchiseptica in the unciliated olfactory epithelia of the nasal cavity.     

Experimental respiratory infection with Pasteurella multocida and Bordetella bronchiseptica in rabbits.

Eight-to-10-wk-old offspring of a colony of specific pathogen free [Eda:(NZW x FG)F1BR] rabbits were exposed to cultures of Pasteurella multocida and Bordetella bronchiseptica. Two groups of 9 animals each were exposed to cultures of either species of bacteria intranasally and killed 2, 7, 14, and 21 da postinoculation. Five of 9 rabbits in each group developed a mucopurulent nasal discharge 4-7 da postinoculation. The remaining 4 rabbits in each group failed to develop clinical signs. The gross and microscopic lesions did not differ in character or distribution among the inoculated rabbits. The infection was characterized by an acute upper respiratory syndrome accompanied by a mild bronchopneumonia.     

Expression of urease does not affect the ability of Bordetella bronchiseptica to colonise and persist in the murine respiratory tract

To investigate the role played by urease during the Bordetella bronchiseptica infection process, the ability to colonise and persist in the mouse respiratory tract of a urease-negative B. bronchiseptica BB7865 and a BB7865 derivative constitutively expressing urease was compared with that of the wild-type strain. The results obtained showed that neither constitutive expression nor abolishment of urease activity had any significant effect on the course of B. bronchiseptica infection. Therefore, under our experimental conditions, urease is not essential for B. bronchiseptica to colonise and persist within the murine host.     

Management of upper respiratory tract infections by telephone.

We surveyed Utah general internists (N = 134) regarding their attitudes toward and practices associated with telephone management of upper respiratory tract infections. The questionnaire contained 3 case vignettes--viral upper respiratory tract infection, streptococcal pharyngitis, and acute infectious epiglottitis--and a series of questions were asked about telephone diagnosis, management preferences (clinic versus telephone), and telephone management practices. The 53 respondents (40%) were able to make important diagnostic distinctions about upper respiratory tract infections from a written vignette. As the likelihood of a complicated or serious condition increased, patients would be appropriately triaged for clinical evaluation. Most internists would make a written record of the telephone conversation. Only 1 internist of the 53 would charge for telephone management.     

Enhancement of Bordetella parapertussis infection by Bordetella pertussis in mixed infection of the respiratory tract

The epidemiological and pathogenic relationship between Bordetella pertussis and Bordetella parapertussis, the two causes of whooping cough (pertussis), is unclear. We hypothesized that B. pertussis, due to its immunosuppressive activities, might enhance B. parapertussis infection when the two species were present in a coinfection of the respiratory tract. The dynamics of this relationship were examined using the mouse intranasal inoculation model. Infection of the mouse respiratory tract by B. parapertussis was not only enhanced by the presence of B. pertussis, but B. parapertussis significantly outcompeted B. pertussis in this model. Staggered inoculation of the two organisms revealed that the advantage for B. parapertussis is established at an early stage of infection. Coadministration of PT enhanced B. parapertussis single infection, but had no effect on mixed infections. Mixed infection with a PT-deficient B. pertussis strain did not enhance B. parapertussis infection. Interestingly, the depletion of airway macrophages reversed the competitive relationship between these two organisms, but the depletion of neutrophils had no effect on mixed infection or B. parapertussis infection. We conclude that B. pertussis, through the action of PT, can enhance a B. parapertussis infection, possibly by an inhibitory effect on innate immunity.     

CD11b is required for the resolution of inflammation induced by Bordetella bronchiseptica respiratory infection

CD11b is a cell surface receptor that contributes to many cellular processes which are involved in the generation of a protective immune response against pathogenic organisms. In this work, the natural host-pathogen model of murine Bordetella bronchiseptica infection was used to explore the role of CD11b in respiratory immunity. Following intranasal inoculation, CD11b-/- mice rapidly succumb to B. bronchiseptica respiratory infection, highlighting the prominent role of CD11b in the generation of a protective immune response in this model. CD11b appears to be required for both the control of bacterial numbers and the regulation of cellular responses in the lungs. An increased accumulation of neutrophils in the lungs of CD11b-/- mice as compared with wild-type mice suggests that CD11b contributes to the regulation of cellular responses to respiratory infection. This accumulation may be explained by a decrease in apoptosis that is observed in the absence of CD11b following cellular interactions with B. bronchiseptica. Interestingly, this role for CD11b in the regulation of cellular accumulation appears to be critically important for the resolution of damage associated with the type III secretion system (TTSS) of B. bronchiseptica. These data provide new insight into the key role CD11b plays in the resolution of damage in the lower respiratory tract, as well as the B. bronchiseptica virulence determinant that induces it.     

Characterization of the common antigenic lipopolysaccharide O-chains produced by Bordetella bronchiseptica and Bordetella parapertussis

Porins of Salmonella minnesota, R595, were purified by anion exchange chromatography and subsequently isolated in their monomeric form by chromatofocusing. Two forms of porin could be isolated, both with an apparent molecular mass of 37,000, but of differing isoelectric points (pI 4.6 versus pI of 4.9). Porins with pI 4.9 did not contain any detectable LPS, but porins with pI 4.6 were found to contain trace amounts of LPS (1.3 x 10(-4) micrograms LPS/1 microgram porin) as measured using a highly sensitive limulus assay. Unlike the LPS-associated porins the monomeric porins were biologically inert with regard to pore formation, but they were still able to bind C1q, a subcomponent of the first component of complement.     

Production of biomass and filamentous hemagglutinin by Bordetella bronchiseptica

The mammalian pathogen Bordetella bronchiseptica was grown under controlled batch conditions with glutamate as the primary carbon and nitrogen source. First, a Box-Behnken statistical design quantified the effect of Mg, sulfate, and nicotinate on the antigen filamentous hemagglutinin (FHA) formation. Using lactic acid as a secondary carbon source for pH control, Mg, and SO₄ each negatively affected antigen expression, while nicotinate positively affected antigen expression. Sulfate had a stronger negative effect than Mg with 10 mM eliminating FHA altogether; the highest FHA expression (about 1,000 ng/mL) occurred when either Mg concentration or SO₄ concentration, but not both, was about 0.1 mM. Using two Mg and SO₄ compositions modeled to yield the greatest antigen expression, three other organic acids were compared as the secondary carbon source: acetate, citrate, and succinate. Mixtures of acetate and glutamate resulted in the greatest organic acid consumption, OD, and FHA concentration (about 1,500 ng/mL), although significant acetate accumulated during these batch processes. The mechanism leading to elevated FHA expression when acetate is the secondary carbon source is unknown, particularly since these cultures were most prone to phase shift to Bvg^? cultures.     

The structure of the carbohydrate backbone of the lipopolysaccharides from Bordetella hinzii and Bordetella bronchiseptica.

The structure of the core-lipid A region of the lipopolysaccharides from Bordetella hinzii and Bordetella bronchiseptica has been analyzed. Lipopolysaccharides were deacylated using strong alkaline hydrolysis, the products were separated by high performance anion-exchange chromatography and analyzed by NMR and mass spectrometry. The following structure of the products can be deduced from the experimental results: where for the product from Bordetella hinzii N = H, R = H, beta-FucN4N- or partially N-acetylated Sug-(1-3)-beta-FucN4N and for the product from Bordetella bronchiseptica N = alpha-Hep, R = H, beta-FucN4N, beta-FucN4NMe or partially N-acetylated Sug-(1-3)-beta-FucN4N or Sug-(1-3)-beta-FucN4NMe; Sug = 2,3-diamino-2,3, 4-trideoxy-hex-4-enuronopyranosyl.     

Bordetella bronchiseptica expresses the fimbrial structural subunit gene fimA.

The differential host species specificities of Bordetella pertussis, B. parapertussis, and B. bronchiseptica might be explained by polymorphisms in adherence factor genes. We have found that B. parapertussis and B. bronchiseptica, unlike B. pertussis, contain a full-length gene for the fimbrial subunit FimA. B. bronchiseptica expresses fimA in a BvgAS-dependent fashion.     

Identification of alcaligin as the siderophore produced by Bordetella pertussis and B. bronchiseptica.

The siderophores produced by iron-starved Bordetella pertussis and B. bronchiseptica were purified and were found to be identical. Using mass spectrometry and proton nuclear magnetic resonance, we determined that the siderophore produced by these organisms was identical to alcaligin, a siderophore produced by Alcaligenes denitrificans.     

Autoflora in the upper respiratory tract of Apollo astronauts.

The typical microbial inhabitants of the oral and nasal cavities of Apollo astronauts were identified before space flight and generally found to be similar to those previously reported for healthy male adults. Additional analyses of samples collected immediately after return of the Apollo 13, 14, 15, and 16 crew members to earth were performed to evaluate the effects of space travel on the microbial bioburden of the upper respiratory tract. In-flight cross-contamination and buildup of pathogens such as Staphylococcus aureus were noted, although significant increases in nonpathogenic species were absent. Other proposed alterations, such as dysbacteriosis (flooding of the mouth with a single species) and simplification of the autoflora, did not occur. Generally, the incidence and quantitation of each species after flight was within the preflight range, although the number of viable Haemophilus cells recovered from the mouth decreased significantly after space flight. Except for those minor alterations listed above, the aerobic and anaerobic bacterial components of the upper respiratory autoflora of Apollo astronauts was found to be stable after space flight of up to 295 h.     

Epithelial secretion of C3 promotes colonization of the upper urinary tract by Escherichia coli.

To assess the role of complement in renal infection, we studied a model of Escherichia coli-induced pyelonephritis in mice deficient in complement components C3 and C4. Renal infection occurred less frequently in C3- and C4-deficient mice compared with wild-type mice. In vitro, renal epithelial cells internalized fewer bacteria in the absence of C3 or in the presence of blockade of C3 bound to the bacteria. Moreover, upregulation of epithelial C3 production by stimulation with lipopolysaccharide enhanced bacterial internalization. Here we provide evidence that uropathogenic E. coli might use host C3 to invade the renal epithelium and that local complement production is sufficient for the bacteria to achieve this effect.