Polymerase chain reaction-based identification of clinically relevant Pasteurellaceae isolated from cats and dogs in Poland

Pasteurella canis soft tissue infection after a cat bite - A case report

Pasteurella canis is a Gram-negative facultative anaerobic bacterium that is a typical commensal of the oral cavity and enteric tract of domestic animals. Human infections caused by this species are most often associated with dog bites and rarely with other animal bites. In this report, we present a case of a 34-year-old man who developed P. canis soft tissue infection of the left hand after a cat bite. The patient was successfully treated by a surgical intervention and antibiotics. The species identification of the isolate was performed by a conventional automatic system and nucleic acid-based methods. The nucleic acid-based methods provide a powerful alternative to the conventional microbiological diagnostic of these bacteria.

Pasteurella multocida causes liver injury in ducks by mediating inflammatory, apoptotic and autophagic pathways

Pasteurella multocida.(PM) infection is a major cause of avian cholera, but the pathogenesis of the disease is unknown. The purpose of this study was to further understand the host response to infection by using a duck model of PM, 20 female ducks were divided into two groups (n = 10). One group was infected with PM, while the other served as an uninfected control group. The ducks were observed after infection and samples were collected for testing. In this study, we report the mechanism of PM-induced inflammation to further mediate apoptosis and autophagic signaling pathways in liver cells. Our results demonstrated that PM infection initially induces hemorrhagic and necrotic lesions in the liver tissue of duck, promoting inflammasome assembly and release, triggering inflammation. The TLR4/NF-κB axis activated and interacted with multiple inflammation-related proteins, including TNF-α and IL-1β, which affected apoptosis and autophagy. Tumor necrosis factor induced hepatocyte apoptosis was implicated in a wide range of liver diseases; the release of TNF-α and activation with NF-κB further incite apoptotic pathways,such as Bax/BCL2/caspase to promote apoptotic genes APAF1, Bax, Caspase3, BCL-2, p53, and Cytc expression. Finally, PM-induced autophagy suppressed liver injury by promoting the Beclin-1, LC3B, p62, and mTOR. Thus, liver injury caused by PM via promoting autophagy was induced. In conclusion, we analyzed the liver injury of ducks infected with PM, and confirmed that inflammation appeared in the liver; this was followed by the intricate interplay between inflammation, apoptosis, and autophagy signaling pathways. The observed results provided a reference basis for studying pathogenic mechanisms of PM-host interactions.

Double semen collection at a 1-h interval in dogs decreases the bacterial contamination of canine ejaculates

Semen extenders usually contain antibiotics with the aim to minimize bacterial growth, but the indiscriminate use of antibiotics increases the emergence of multidrug-resistant bacteria. A limiting factor of semen processing in dogs is the low total sperm count that limits the number of insemination doses that can be obtained from one ejaculate. Therefore, two ejaculates collected at a short interval can be combined to increase the number of AI doses. In this study, semen was collected from dogs either once or the same dogs (n = 28) were submitted to dual semen collection 1 h apart. All ejaculates were submitted to bacteriological analysis. We hypothesized that bacterial contamination of semen is low but that a dual semen collection might increase contamination. A sample for bacteriological examination was taken from raw semen immediately after semen collection. Bacteria including mycoplasmas were isolated using conventional cultivation procedures and isolates were identified to the species level by matrix-assisted laser desorption ionization - time of flight (MALDI-ToF) mass spectrometry. In total, 22 bacterial species were identified in the 84 ejaculates with Mycoplasma cynos, Streptococcus canis and Canicola haemoglobinophilus being most frequent. Bacterial growth was sporadic in 16 and absent in 10 ejaculates. The overall bacterial growth was lower in the second than in the first ejaculate of dual semen collections (p < 0.05). The percentage of motile and membrane-intact spermatozoa in frozen-thawed ejaculates was not associated with the degree of bacterial contamination of raw semen. In conclusion, there was only limited microbial contamination in dog semen and the microorganisms isolated are considered part of the normal genital bacterial flora. Repeated semen collection reduced bacterial contamination in the second in comparison to the first ejaculate. The use of antibiotics in canine semen should be questioned.

Occurrence of Pasteurella multocida in Dogs Being Trained for Animal-Assisted Therapy

Animal-assisted therapy (AAT) is a non-pharmacological therapy aimed at people with physical and/or mental disabilities. Therefore, it is necessary to carry out interventions that guarantee its benefits for patients while also avoiding the risk of zoonoses due to contact with the animals or their mucous membranes. The present study aimed to detect the occurrence of Pasteurella multocida in the oral cavity of dogs attending a “dog educational centre” and training for AAT interventions. In addition, some of the potential predictable factors of infection (i.e., age, sex, breed, and living conditions) were analyzed. In total, 25/200 dogs examined (12.5%; 95% confidence interval = 8.4–18.1%) were positive for P. multocida, as confirmed by PCR. Sex, breed, and living conditions were risk factors associated with P. multocida as revealed by the logistic regression analysis. Specifically, cross-bred female dogs living prevalently outdoors were significantly associated with the presence of P. multocida (p < 0.05). This study represents the first epidemiological survey of the prevalence of P. multocida in the oral cavity of dogs involved subsequently in AAT interventions, highlighting the potential risk of P. multocida infection in patients, often belonging to risk categories (e.g., children, the elderly, and immunocompromised individuals). Therefore, healthcare guidelines could be suggested to integrate the current literature related to the health check of dogs involved in AAT. In this way, it could be ensured that, even with bodily contact during AAT, the risk of pathogen transmission by the co-therapist dog can be avoided.

A loop-mediated isothermal amplification procedure targeting the sodA gene for rapid and specific identification of Gallibacterium anatis

This paper reports on the development and validation of a real-time loop-mediated isothermal amplification assay (LAMP) for rapid and specific identification of Gallibacterium anatis. To design a set of 6 primers using the LAMP technique, the conserved region of the G. anatis sodA gene was selected as a target. To evaluate primer specificity we used 120 field strains, the reference strain G. anatis ATCC 43329, and 9 non-G. anatis bacteria. The results confirmed positive reactions for all G. anatis strains tested by LAMP at 63°C for 60 min, with no cross-reactivity observed for the negative control bacteria, i.e., Haemophilus parainfluenzae (ATCC 51505 and ATCC 33392), Aggregatibacter aphrophilus ATCC 7901, Avibacterium endocarditis, Pasteurella multocida, Actinobacillus pleuropneumoniae, Avibacterium paragallinarum, Ornithobacterium rhinotracheale, and Escherichia coli. The lowest detectable amount of DNA for the LAMP reaction was 0.2561 pg, which was detected in about 34 min, while the highest available concentration of the G. anatis reference strain was detected in about 10 min. The lowest detectable amount of DNA for the real-time PCR reaction was 21.24 pg, which was detected in about 20 min, while the highest available concentration of the G. anatis reference strain was detected in about 7 min. Moreover, using the real-time LAMP assay the reaction could be effectively carried out in a volume of just 13 μL, about half the officially recommended reaction volume (25 μL). The aim of this study was to develop a highly sensitive and specific G. anatis real-time LAMP assay that is less time-consuming and less costly than quantitative PCR.

PCR-Based Analysis of ColE1 Plasmids in Clinical Isolates and Metagenomic Samples Reveals Their Importance as Gene Capture Platforms

ColE1 plasmids are important vehicles for the spread of antibiotic resistance in the Enterobacteriaceae and Pasteurellaceae families of bacteria. Their monitoring is essential, as they harbor important resistant determinants in humans, animals and the environment. In this work, we have analyzed ColE1 replicons using bioinformatic and experimental approaches. First, we carried out a computational study examining the structure of different ColE1 plasmids deposited in databases. Bioinformatic analysis of these ColE1 replicons revealed a mosaic genetic structure consisting of a host-adapted conserved region responsible for the housekeeping functions of the plasmid, and a variable region encoding a wide variety of genes, including multiple antibiotic resistance determinants. From this exhaustive computational analysis we developed a new PCR-based technique, targeting a specific sequence in the conserved region, for the screening, capture and sequencing of these small plasmids, either specific for Enterobacteriaceae or specific for Pasteurellaceae. To validate this PCR-based system, we tested various collections of isolates from both bacterial families, finding that ColE1 replicons were not only highly prevalent in antibiotic-resistant isolates, but also present in susceptible bacteria. In Pasteurellaceae, ColE1 plasmids carried almost exclusively antibiotic resistance genes. In Enterobacteriaceae, these plasmids encoded a large range of traits, including not only antibiotic resistance determinants, but also a wide variety of genes, showing the huge genetic plasticity of these small replicons. Finally, we also used a metagenomic approach in order to validate this technique, performing this PCR system using total DNA extractions from fecal samples from poultry, turkeys, pigs and humans. Using Illumina sequencing of the PCR products we identified a great diversity of genes encoded by ColE1 replicons, including different antibiotic resistance determinants, supporting the previous results achieved with the collections of bacterial isolates. In addition, we detected cryptic ColE1 plasmids in both families with no known genes in their variable region, which we have named sentinel plasmids. In conclusion, in this work we present a useful genetic tool for the detection and analysis of ColE1 plasmids, and confirm their important role in the dissemination of antibiotic resistance, especially in the Pasteurellaceae family of bacteria.

A novel quantitative real-time polymerase chain reaction method for detecting toxigenic Pasteurella multocida in nasal swabs from swine

BACKGROUND

Progressive atrophic rhinitis (PAR) in pigs is caused by toxigenic Pasteurella multocida. In Switzerland, PAR is monitored by selective culture of nasal swabs and subsequent polymerase chain reaction (PCR) screening of bacterial colonies for the P. multocida toxA gene. A panel of 203 nasal swabs from a recent PAR outbreak were used to evaluate a novel quantitative real-time PCR for toxigenic P. multocida in porcine nasal swabs.

RESULTS

In comparison to the conventional PCR with a limit of detection of 100 genome equivalents per PCR reaction, the real-time PCR had a limit of detection of 10 genome equivalents. The real-time PCR detected toxA-positive P. multocida in 101 samples (49.8%), whereas the conventional PCR was less sensitive with 90 toxA-positive samples (44.3%). In comparison to the real-time PCR, 5.4% of the toxA-positive samples revealed unevaluable results by conventional PCR.

CONCLUSIONS

The approach of culture-coupled toxA PCR for the monitoring of PAR in pigs is substantially improved by a novel quantitative real-time PCR.