Clonal outbreaks of [ Pasteurella] pneumotropica biovar Heyl in two mouse colonies.

The aim of this study was to document the pathogenic role of biovar Heyl of [ Pasteurella] pneumotropica in mouse colonies. Fifty-three isolates associated with mastitis and orbital, cutaneous and vaginal abscesses as well as isolates from the nose and vagina of healthy mice were investigated. According to phenotypic characteristics and rpoB sequencing, the isolates were identified as [ P.] pneumotropica biovar Heyl. Pulsed-field gel electrophoresis (PFGE) revealed five closely related profiles separated by only one to four fragments. The outbreak strains diverged from epidemiologically unrelated strains with the same rpoB sequence type, as shown by the PFGE profiles. The investigation documented that members of biovar Heyl of [ P.] pneumotropica caused disease outbreaks in mouse colonies since the clonality indicated a primary role of [ P.] pneumotropica biovar Heyl in the infections observed.

Identification of a virulence determinant that is conserved in the Jawetz and Heyl biotypes of [Pasteurella] pneumotropica.

[Pasteurella] pneumotropica is a ubiquitous bacterium frequently isolated from laboratory rodents. Although this bacterium causes various diseases in immunosuppressed animals, little is known about major virulence factors and their roles in pathogenicity. To identify virulence factors, we sequenced the genome of [P.] pneumotropica biotype Heyl strain ATCC 12555, and compared the resulting non-contiguous draft genome sequence with the genome of biotype Jawetz strain ATCC 35149. Among a large number of genes encoding virulence-associated factors in both strains, four genes encoding for YadA-like proteins, which are known virulence factors that function in host cell adherence and invasion in many pathogens. In this study, we assessed YadA distribution and biological activity as an example of one of virulence-associated factor shared, with biotype Jawetz and Heyl. More than half of mouse isolates were found to have at least one of these genes; whereas, the majority of rat isolates did not. Autoagglutination activity, and ability to bind to mouse collagen type IV and mouse fibroblast cells, was significantly higher in YadA-positive than YadA-negative strains. To conclude, we identified a large number of candidate genes predicted to influence [P.] pneumotropica pathogenesis.

Perturbations in cytokine gene expression after inoculation of C57BL/6 mice with Pasteurella pneumotropica.

Pasteurella pneumotropica can cause inflammation and abscess formation in a variety of tissues. Most commonly, P. pneumotropica produces clinical disease in immunodeficient mice or those concurrently infected with other pathogens. Because clinical disease is infrequent in immunocompetent mice harboring P. pneumotropica, some scientists consider it an opportunistic pathogen with little clinical relevance to biomedical research. However, other infectious agents, including mouse parvoviruses, mouse rotavirus, and Helicobacter spp. alter physiologic or biologic responses without causing clinical signs of illness. We investigated the potential for P. pneumotropica to modulate the transcription of cytokine genes in immunocompetent mice. In C57BL/6 mice inoculated oronasally with a minimal colonizing dose of P. pneumotropica, modest but statistically significant elevations of IL1beta, TNFalpha, CCL3, CXCL1, and CXCL2 mRNA were detected in mandibular and superficial cervical lymph nodes at 7 d after inoculation, and upregulation of IL1beta mRNA was detected 28 d after inoculation. These perturbations were not present in C57/BL6 mice inoculated with heat killed-P. pneumotropica or the related bacterium Actinobacillus muris. Nasal mucosal cytokine transcription did not vary significantly in C57BL/6 mice given a high dose of P. pneumotropica. These data indicate that slight and transient experimental perturbations are possible in immunocompetent mice colonized with P. pneumotropica. Knowing the full health status of experimental mice is paramount to avoid unwanted experimental variables, especially when using exquisitely sensitive testing methodologies such as those for quantification of gene expression.

[Pasteurella pneumotropica produces regression of human tumors transplanted in immunodeficiency mice]. / Pasteurella pneumotropica causa la regresión de tumores humanos trasplantados en ratones inmunodeficientes.

The technique of human tumor cell line transplantation in immunodeficient mice is used worldwide as a model for cancer research. In accordance with international recommendations, animals used in biomedical research should be free of microorganisms which can interfere in experimental results; including Pasteurella pneumotropica. The object of this study was to evaluate the interference produced by P. pneumotropica in the human adenocarcinoma cell line A549 transplanted in N:NIH(S)-nu mice. A total of 40 mice divided into 4 groups of 10 animals each was used to perform this study. Group 1: inoculated with the cell line; group 2, with the bacteria; group 3, with the cell line and the bacteria; group 4, as control with no inoculations. Significant differences were observed in tumor growth in groups 1 and 3, infected and not infected with P. pneumotropica. Although this microorganism is non lethal and only opportunistic, the infected animals are to be considered not suitable to be transplanted with the tumor cell line A549 for experimental studies since these bacteria interfere with tumor growth. However, the fact that a growing tumor regresses in the presence of the bacteria is an interesting observation which deserves further exploration in order to elucidate the mechanism involved.

Pasteurella pneumotropica causa la regresion de tumores humanos trasplantados en ratones inmunodeficientes / Pasteurella pneumotropica produces regression of human tumors transplanted in immunodeficiency mice

La técnica de trasplante de tumores humanos en ratones inmunodeficientes es muy utilizada como modelo en investigaciones sobre el cáncer. De acuerdo con las recomendaciones internacionales, los animales de experimentación deben estar libres de los micoorganismos que interfieren en los resultados finales de las investigaciones, dentro de los cuales se encuentra Pasteurella pneumotropica. En el presente trabajo se evaluó la interferencia que produce esta bacteria en el crecimiento de la línea celular A549 de adenocarcinoma humano trasplantada en ratones de la cepa nude N:NIH (S)-nu. Se utilizaron 40 ratones divididos en 4 grupos de 10 animales cada uno. Grupo 1: inoculados con la línea celular; grupo 2, con la bacteria; grupo 3, con la línea celular y la bacteria y grupo 4, el control sin inoculaciones. Se observaron diferencias significativas en el crecimiento tumoral entre los animales de los grupos 1 y 3. Si bien este microorganismo es un patógeno oportunista no letal, los ratones trasplantados con la línea celular A549 e infectados con P. pneumotropica no son aptos para utilizarse como modelo animal en estudios sobre el cáncer debido a que esta bacteria interfiere en el desarrollo de la línea tumoral, con la consecuente interpretación errónea de los resultados. Pero el hecho que la bacteria haya causado la regresión de un tumor en pleno crecimiento es inesperado y el mecanismo de acción será objeto de futuros experimentos.

The technique of human tumor cell line transplantation in immunodeficient miceis used worldwide as a model for cancer research. In accordance with international recommendations, animals used in biomedical research should be free of microorganisms which can interfere in experimental results; including Pasteurella pneumotropica. The object of this study was to evaluate the interference produced by P. pneumotropica in the human adenocarcinoma cell line A549 transplanted in N:NIH(S)-nu mice. A total of 40 mice divided into 4 groups of 10 animals each was used to perform this study. Group 1: inoculated with the cell line; group 2, with the bacteria; group 3, with the cell line and the bacteria; group 4, as control with no inoculations. Significant differences were observed in tumor growth in groups 1 and 3, infected and not infected with P. pneumotropica. Although this microorganism is non lethal and only opportunistic, the infected animals are to be considered not suitable to be transplanted with the tumor cell line A549 for experimental studies since these bacteria interfere with tumor growth. However, the fact that a growing tumor regresses in the presence of the bacteria is an interesting bservation which deserves further exploration in order to elucidate the mechanism involved.

Pasteurella pneumotropica causa la regresion de tumores humanos trasplantados en ratones inmunodeficientes / Pasteurella pneumotropica produces regression of human tumors transplanted in immunodeficiency mice

La técnica de trasplante de tumores humanos en ratones inmunodeficientes es muy utilizada como modelo en investigaciones sobre el cáncer. De acuerdo con las recomendaciones internacionales, los animales de experimentación deben estar libres de los micoorganismos que interfieren en los resultados finales de las investigaciones, dentro de los cuales se encuentra Pasteurella pneumotropica. En el presente trabajo se evaluó la interferencia que produce esta bacteria en el crecimiento de la línea celular A549 de adenocarcinoma humano trasplantada en ratones de la cepa nude N:NIH (S)-nu. Se utilizaron 40 ratones divididos en 4 grupos de 10 animales cada uno. Grupo 1: inoculados con la línea celular; grupo 2, con la bacteria; grupo 3, con la línea celular y la bacteria y grupo 4, el control sin inoculaciones. Se observaron diferencias significativas en el crecimiento tumoral entre los animales de los grupos 1 y 3. Si bien este microorganismo es un patógeno oportunista no letal, los ratones trasplantados con la línea celular A549 e infectados con P. pneumotropica no son aptos para utilizarse como modelo animal en estudios sobre el cáncer debido a que esta bacteria interfiere en el desarrollo de la línea tumoral, con la consecuente interpretación errónea de los resultados. Pero el hecho que la bacteria haya causado la regresión de un tumor en pleno crecimiento es inesperado y el mecanismo de acción será objeto de futuros experimentos.(AU)

The technique of human tumor cell line transplantation in immunodeficient miceis used worldwide as a model for cancer research. In accordance with international recommendations, animals used in biomedical research should be free of microorganisms which can interfere in experimental results; including Pasteurella pneumotropica. The object of this study was to evaluate the interference produced by P. pneumotropica in the human adenocarcinoma cell line A549 transplanted in N:NIH(S)-nu mice. A total of 40 mice divided into 4 groups of 10 animals each was used to perform this study. Group 1: inoculated with the cell line; group 2, with the bacteria; group 3, with the cell line and the bacteria; group 4, as control with no inoculations. Significant differences were observed in tumor growth in groups 1 and 3, infected and not infected with P. pneumotropica. Although this microorganism is non lethal and only opportunistic, the infected animals are to be considered not suitable to be transplanted with the tumor cell line A549 for experimental studies since these bacteria interfere with tumor growth. However, the fact that a growing tumor regresses in the presence of the bacteria is an interesting bservation which deserves further exploration in order to elucidate the mechanism involved.(AU)

Pasteurella pneumotropica causa la regresion de tumores humanos trasplantados en ratones inmunodeficientes / Pasteurella pneumotropica produces regression of human tumors transplanted in immunodeficiency mice

La técnica de trasplante de tumores humanos en ratones inmunodeficientes es muy utilizada como modelo en investigaciones sobre el cáncer. De acuerdo con las recomendaciones internacionales, los animales de experimentación deben estar libres de los micoorganismos que interfieren en los resultados finales de las investigaciones, dentro de los cuales se encuentra Pasteurella pneumotropica. En el presente trabajo se evaluó la interferencia que produce esta bacteria en el crecimiento de la línea celular A549 de adenocarcinoma humano trasplantada en ratones de la cepa nude N:NIH (S)-nu. Se utilizaron 40 ratones divididos en 4 grupos de 10 animales cada uno. Grupo 1: inoculados con la línea celular; grupo 2, con la bacteria; grupo 3, con la línea celular y la bacteria y grupo 4, el control sin inoculaciones. Se observaron diferencias significativas en el crecimiento tumoral entre los animales de los grupos 1 y 3. Si bien este microorganismo es un patógeno oportunista no letal, los ratones trasplantados con la línea celular A549 e infectados con P. pneumotropica no son aptos para utilizarse como modelo animal en estudios sobre el cáncer debido a que esta bacteria interfiere en el desarrollo de la línea tumoral, con la consecuente interpretación errónea de los resultados. Pero el hecho que la bacteria haya causado la regresión de un tumor en pleno crecimiento es inesperado y el mecanismo de acción será objeto de futuros experimentos.(AU)

The technique of human tumor cell line transplantation in immunodeficient miceis used worldwide as a model for cancer research. In accordance with international recommendations, animals used in biomedical research should be free of microorganisms which can interfere in experimental results; including Pasteurella pneumotropica. The object of this study was to evaluate the interference produced by P. pneumotropica in the human adenocarcinoma cell line A549 transplanted in N:NIH(S)-nu mice. A total of 40 mice divided into 4 groups of 10 animals each was used to perform this study. Group 1: inoculated with the cell line; group 2, with the bacteria; group 3, with the cell line and the bacteria; group 4, as control with no inoculations. Significant differences were observed in tumor growth in groups 1 and 3, infected and not infected with P. pneumotropica. Although this microorganism is non lethal and only opportunistic, the infected animals are to be considered not suitable to be transplanted with the tumor cell line A549 for experimental studies since these bacteria interfere with tumor growth. However, the fact that a growing tumor regresses in the presence of the bacteria is an interesting bservation which deserves further exploration in order to elucidate the mechanism involved.(AU)

An outbreak of Pasteurella pneumotropica in genetically modified mice: treatment and elimination.

A closed breeding colony comprising genetically engineered, wild-type, and stock mice presented with varying degrees of bilateral mucopurulent conjunctivitis and panophthalmitis. The one mouse with unilateral corneal ulceration, a knockout animal, was submitted for necropsy, and bacterial culture samples were obtained from the affected eye and uterus. In addition, ocular swabs from another 12 clinically affected animals, consisting of knockout, transgenic, wild-type, and stock mice, were submitted for bacterial culture analysis. All samples revealed pure cultures of Pasteurella pneumotropica. At the time of the outbreak, there were approximately 600 mice in the affected colony, with the majority of clinical cases (58 of 79) involving knockout mice and the remainder (21 of 79) in the other strains. Treatment consisted of enrofloxacin in the drinking water at 85 mg/kg daily for 14 days. Within 7 days of initiation of treatment, all existing clinical cases had resolved and no new clinical cases developed. Four weeks after completion of treatment, two groups of mice were submitted for multiple organ bacteriological analyses. One group of mice represented those animals which had complete resolution of clinical signs, and the second group of mice represented those individuals which had remained asymptomatic throughout the outbreak. All post treatment bacterial culture samples were negative for Pasteurella pneumotropica. By using the oral enrofloxacin suspension in the drinking water rather than the parenteral counterpart, concerns regarding the pharmacokinetics, specifically drug bioavailability via the oral route, problems with aqueous immiscibility and drug degradation within an aqueous medium were not potentially confounding variables. The clinical management, ease of administration, and efficacy of using an oral antibiotic formulation for the treatment and eradication of Pasteurella pneumotropica from a large mouse colony are presented in this paper.