Antimicrobial Resistance in Bordetella bronchiseptica

Identification of a broad-spectrum lytic Bordetella phage and assessments of its potential for combating Bordetella infections

Bordetella bronchiseptica (Bb) is a zoonotic respiratory pathogen that frequently causes infections in farming and companion animals, posing threats to agricultural economics and public health. However, Bb strains are intrinsically resistant to several antibiotics commonly used to treat respiratory infections. Phage therapy has been recognized as a promising strategy to combat bacterial infections. In this study, a novel Bordetella phage, designated PY223, was isolated using Bb strains as indicators. Genome network analysis with different phages showed PY223 was related to 15 viral clusters but was not included in any of these clusters. PY223 did not carry any known genes involved in lysogeny and/or horizontal gene transfer. Host range analysis showed that PY223 exhibited the capacity to lyse 70 Bb strains isolated from pigs and/or cats. Measurement of the one-step growth curve showed that PY223 had an incubation period of 10 min and a rapid growth period of 80 min. The burst size was estimated to be approximately 109 PFU/cell. In addition, PY223 displayed the capacity to inhibit the growth of Bb for up to 17 h. PY223 was stable under environmental temperatures ranging from 4 °C to 60 °C and/or pH values between 5.0 and 9.0. It remained stable even when exposed to UV light for 30 min. Notably, PY223 effectively eliminated Bb biofilms, inhibited the growth of prophage-harboring Bb strains, and cleared Bb from the environment. In vivo testing in mouse models highlighted its excellent potential for treating respiratory Bordetella infections.

First identification of Bordetella bronchiseptica subclinical mastitis in a lactating dairy cow in New Zealand

CASE HISTORY

A gland of a cow with a high somatic cell count (385,000 cells/mL at 116 days in milk) was enrolled in a therapeutic subclinical mastitis study following a positive pre-enrolment culture. One week later, the quarter was treated with 1 g of procaine penicillin on three occasions, 12 hours apart (Day 0 and 1). A further milk sample was obtained from the quarter on Days 6, 14, and 21 after initiation of treatment.

CLINICAL FINDINGS

Milk samples were submitted for routine bacteriological culture and matrix-assisted laser desorption/ionised time-of-flight mass spectrometry (MALDI-TOF) analysis. A Gram-negative motile rod was isolated from all samples which could not be speciated using the laboratory's standard panel of biochemical tests. The isolates were identified by MALDI-TOF as Bordetella bronchiseptica. Whole genome sequencing and comparison with publicly available genomic sequences showed that the bovine isolate did not cluster with any previously published B. bronchiseptica sequences.

DIAGNOSIS

Subclinical mastitis caused by infection with Bordetella bronchiseptica.

CLINICAL RELEVANCE

Only one other case report could be found of this organism being identified in milk samples. Greater use of advanced identification systems will likely increase the number of organisms identified from mastitic milk samples. Appropriate identification is important to aid decision-making as, given the response to therapy and laboratory findings, there is a poor likelihood of bacteriological cure with beta-lactam therapy for this organism.

Detection and Whole-Genome Characteristics of Bordetella trematum Isolated from Captive Snakes

Bordetella trematum is a rare member of the genus Bordetella, primarily associated with human wound infections rather than respiratory diseases. The bacterium has been isolated from various clinical specimens, including ear inflammatory discharge, diabetic ulcers, and chronic wounds. The study aimed to characterize the genomes and antimicrobial resistance (AMR) profiles of B. trematum obtained from the fecal samples of asymptomatic highland eyelash pit vipers (Bothriechis schlegelii). The identification was conducted using MALDI-TOF mass spectrometry and biochemical tests. AMR was assessed using the microbroth dilution method, while whole-genome sequencing was performed on the Illumina NextSeq platform. The isolates displayed characteristic B. trematum biochemical features and demonstrated a resistance to cefotaxime, ciprofloxacin, and trimethoprim, while one also exhibited a resistance to ceftazidime. The whole-genome sequencing and comparison with limited public data revealed a high diversity within B. trematum, reaching >48,000 single nucleotide polymorphisms (SNPs), with 64 SNP differentiating tested snake isolates and thus, being considered epidemiologically unrelated. This is the first report of B. trematum isolated from an animal source in Europe. The findings provide valuable insights into this rare bacterium's phenotypic and genomic characteristics, addressing an important knowledge gap in its ecology and AMR profile.

Comparative analysis of antimicrobial resistance and genetic diversity of Bordetella bronchiseptica isolates obtained from swine within the United States

Introduction

Bordetella bronchiseptica is bacterial pathogen that is pervasive in swine populations and serves multiple roles in respiratory disease.

Methods

This study utilized whole-genome sequencing (WGS) analysis to assess the sequence type (ST), identify the genetic diversity of genes predicted to encode regulatory and virulence factors, and evaluated any potential antimicrobial resistance harbored by B. bronchiseptica isolates obtained from swine within the U.S.

Results

While a generally high degree of genomic conservation was observed among the swine B. bronchiseptica isolates, genetic diversity was identified within the fimNX locus and among the sequence type six (ST6) isolates. The majority of B. bronchiseptica isolates exhibited phenotypic resistance to four antibiotic classes, however, only three antimicrobial resistance genes were identified.

Discussion

Combined the data suggests that B. bronchiseptica isolates are not serving as a source of antimicrobial resistance gene transference in the swine production environment.

Case report: First report of Legionella pneumophila and Bordetella bronchiseptica coinfection in an immunocompromised patient

Legionnaires' disease (LD) is a serious type of pneumonia, typically contracted by susceptible people through the inhalation of aerosols contaminated with Legionella pneumophila (Lp). In this report, the first case of coinfection with Lp-Bordetella bronchiseptica (Bb) is described. A possible source of the Lp infection may be the hotel in Paris (France) where the patient had stayed before developing the symptoms. The Bb infection may have been transmitted by the dog with which he had constant contact, although this has not been proven.

Stimulating the biofilm formation of Bacillus populations to mitigate soil antibiotic resistome during insect fertilizer application

Antibiotic resistance in soil introduced by organic fertilizer application pose a globally recognized threat to human health. Insect organic fertilizer may be a promising alternative due to its low antibiotic resistance. However, it is not yet clear how to regulate soil microbes to reduce antibiotic resistance in organic fertilizer agricultural application. In this study, we investigated soil microbes and antibiotic resistome under black soldier fly organic fertilizer (BOF) application in pot and field systems. Our study shows that BOF could stimulate ARB (antibiotic resistant - bacteria) - suppressive Bacillaceae in the soil microbiome and reduce antibiotic resistome. The carbohydrate transport and metabolism pathway of soil Bacillaceae was strengthened, which accelerated the synthesis and transport of polysaccharides to form biofilm to antagonistic soil ARB, and thus reduced the antibiotic resistance. We further tested the ARB - suppressive Bacillus spp. in a microcosm assay, which resulted in a significant decrease in the presence of ARGs and ARB together with higher abundance in key biofilm formation gene (epsA). This knowledge might help to the development of more efficient bio-fertilizers aimed at mitigating soil antibiotic resistance and enhancing soil health, in particular, under the requirements of global "One Health".

Delineating the Acquired Genetic Diversity and Multidrug Resistance in Alcaligenes from Poultry Farms and Nearby Soil

Alcaligenes faecalis is one of the most important and clinically significant environmental pathogens, increasing in importance due to its isolation from soil and nosocomial environments. The Gram-negative soil bacterium is associated with skin endocarditis, bacteremia, dysentery, meningitis, endophthalmitis, urinary tract infections, and pneumonia in patients. With emerging antibiotic resistance in A. faecalis, it has become crucial to understand the origin of such resistance genes within this clinically significant environmental and gut bacterium. In this research, we studied the impact of antibiotic overuse in poultry and its effect on developing resistance in A. faecalis. We sampled soil and faecal materials from five poultry farms, performed whole genome sequencing & analysis and identified four strains of A. faecalis. Furthermore, we characterized the genes in the genomic islands of A. faecalis isolates. We found four multidrug-resistant A. faecalis strains that showed resistance against vancomycin (MIC >1000 μg/ml), ceftazidime (50 μg/ml), colistin (50 μg/ml) and ciprofloxacin (50 μg/ml). From whole genome comparative analysis, we found more than 180 resistance genes compared to the reference sequence. Parts of our assembled contigs were found to be similar to different bacteria which included pbp1A and pbp2 imparting resistance to amoxicillin originally a part of Helicobacter and Bordetella pertussis. We also found the Mycobacterial insertion element IS6110 in the genomic islands of all four genomes. This prominent insertion element can be transferred and induce resistance to other bacterial genomes. The results thus are crucial in understanding the transfer of resistance genes in the environment and can help in developing regimes for antibiotic use in the food and poultry industry.

Antimicrobial Resistance and Biofilm Formation of Bordetella bronchiseptica in Central China, with Evidence of a Rare Heteroresistance Strain to Gentamicin

Bordetella bronchiseptica is a significant contributor to respiratory disease in pigs, leading to substantial economic losses in the swine industry worldwide. We isolated 52 B. bronchiseptica strains from 542 samples collected from pigs with atrophic rhinitis and bronchopneumonia in central China. Multi-locus sequence typing identified two prevalent sequence types: ST6 (69.23%) and ST7 (30.77%). PCR-based detection of seven virulence genes (fhaB, prn, cyaA, dnt, bteA, fla, and bfrZ) revealed that six of these genes were present in over 90% of the isolates, with bfrZ being the exception at 59.62%. Antimicrobial susceptibility testing, performed using the K-B method, demonstrated high sensitivity to enrofloxacin, polymyxin, and doxycycline but a notable resistance to tylosin, trimethoprim, tobramycin, ciprofloxacin, and amikacin. Remarkably, 86.54% of the isolates exhibited a multidrug-resistant phenotype. Notably, we successfully screened a strain of B. bronchiseptica with a heteroresistance phenotype to gentamicin using population analysis profiling, which is a rare case. Biofilm-formation assays indicated that 96.15% of the isolates possessed biofilm-forming capabilities. These findings provide crucial insights into the prevalence of B. bronchiseptica in central China, facilitating the development of effective preventive measures to safeguard both animal and human health.

Canine acquired pneumonia caused by Bordetella bronchiseptica

Here, we present the case of a 55-year-old male with HIV and persistent lymphopenia who developed a paroxysmal severe cough for over three weeks. Microbiology studies were positive for abundant colonies of Bordetella bronchiseptica. He reports that his dog was also ill with a severe cough, suggesting a possible canine-to-human transmission. This zoonosis has been increasingly recognized and possesses significant morbidity and mortality, especially in immunocompromised hosts.

Antimicrobial susceptibility among respiratory tract pathogens isolated from diseased cattle and pigs from different parts of Europe

AIMS

To survey antibiotic susceptibility of bacteria causing cattle and pig respiratory infections in 10 European countries.

METHODS AND RESULTS

Non-replicate nasopharyngeal/nasal or lung swabs were collected from animals with acute respiratory signs during 2015-2016. Pasteurella multocida, Mannheimia haemolytica, Histophilus somni from cattle (n = 281), and P. multocida, Actinobacillus pleuropneumoniae, Glaesserella parasuis, Bordetella bronchiseptica, and Streptococcus suis from pigs (n = 593) were isolated. MICs were assessed following CLSI standards and interpreted using veterinary breakpoints where available. Histophilus somni isolates were fully antibiotic susceptible. Bovine P. multocida and M. haemolytica were susceptible to all antibiotics, except tetracycline (11.6%-17.6% resistance). Low macrolide and spectinomycin resistance was observed for P. multocida and M. haemolytica (1.3%-8.8%). Similar susceptibility was observed in pigs, where breakpoints are available. Resistance in P. multocida, A. pleuropneumoniae, and S. suis to ceftiofur, enrofloxacin, and florfenicol was absent or <5%. Tetracycline resistance varied from 10.6% to 21.3%, but was 82.4% in S. suis. Overall multidrug-resistance was low. Antibiotic resistance in 2015-2016 remained similar as in 2009-2012.

CONCLUSIONS

Low antibiotic resistance was observed among respiratory tract pathogens, except for tetracycline.

A tool to enhance antimicrobial stewardship using similarity networks to identify antimicrobial resistance patterns across farms

Antimicrobial resistance (AMR) is one of the major challenges of the century and should be addressed with a One Health approach. This study aimed to develop a tool that can provide a better understanding of AMR patterns and improve management practices in swine production systems to reduce its spread between farms. We generated similarity networks based on the phenotypic AMR pattern for each farm with information on important bacterial pathogens for swine farming based on the Euclidean distance. We included seven pathogens: Actinobacillus suis, Bordetella bronchiseptica, Escherichia coli, Glaesserella parasuis, Pasteurella multocida, Salmonella spp., and Streptococcus suis; and up to seventeen antibiotics from ten classes. A threshold criterion was developed to reduce the density of the networks and generate communities based on their AMR profiles. A total of 479 farms were included in the study although not all bacteria information was available on each farm. We observed significant differences in the morphology, number of nodes and characteristics of pathogen networks, as well as in the number of communities and susceptibility profiles of the pathogens to different antimicrobial drugs. The methodology presented here could be a useful tool to improve health management, biosecurity measures and prioritize interventions to reduce AMR spread in swine farming.

Genome-wide analysis reveals the emergence of multidrug resistant Stenotrophomonas acidaminiphila strain SINDOREI isolated from a patient with sepsis

Stenotrophomonas acidaminiphila, the most recent reported species in genus Stenotrophomonas, is a relatively rare bacteria and is an aerobic, glucose non-fermentative, Gram-negative bacterium. However, little information of S. acidaminiphila is known to cause human infections. In this research, we firstly reported a multidrug-resistant strain S. acidaminiphila SINDOREI isolated from the blood of a patient with sepsis, who was dead of infection eventually. The whole genome of strain SINDOREI was sequenced, and genome comparisons were performed among six closely related S. acidaminiphila strains. The core genes (2,506 genes) and strain-specific genes were identified, respectively, to know about the strain-level diversity in six S. acidaminiphila stains. The presence of a unique gene (narG) and essential genes involved in biofilm formation in strain SINDOREI are important for the pathogenesis of infections. Strain SINDOREI was resistant to trimethoprim/sulfamethoxazole, ciprofloxacin, ofloxacin, cefepime, ceftazidime, and aztreonam. Several common and specific antibiotic resistance genes were identified in strain SINDOREI. The presence of two sul genes and exclusive determinants GES-1, aadA3, qacL, and cmlA5 is responsible for the resistance to multidrug. The virulence factors and resistance determinants can show the relationship between the phenotype and genotype and afford potential therapeutic strategies for infections.

Bordetella bronchiseptica pneumonia in an immunocompetent pig farmer

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B. bronchiseptica has rarely been isolated from humans despite exposure to animals.

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Working with farm animals, COPD or AIDS are risk factors to develop pneumonia.

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B. bronchiseptica pneumonia may lead to misdiagnosis with other infections.

Bordetella bronchiseptica is a gram negative bacterium, a common pathogen in respiratory infections of various mammals, mainly dogs and pigs, being extremely rare in humans, occurring in these cases especially in immunosuppressed individuals. We present the case of a male pig breeder with no evidence of immunosuppression, initially focused on possible pulmonary tuberculosis, who was diagnosed of B. bronchiseptica pneumonia, successfully treated with fluoroquinolones and doxycycline.

Development and testing of a vaccine against infectious atrophic rhinitis and pasteurellosis in pigs

This work presents the results of the development and testing of a domestic vaccine against infectious atrophic rhinitis and pasteurellosis in pigs caused by Bordetella bronchiseptica and Pasteurella multocida type A and D. A drug was designed with the following antigenic composition: B. bronchiseptica (strain B-1341) - 6 * 109 m.c. / dose; antigen of P. multocida type A (strain B-1303) - 3 * 109 m.c. / dose; antigen of P. multocida type D (strain B-1308) - 3 * 109 m. c. / dose. A 3% solution of Aluminum hydroxide in a proportion of 10% was used as an adjuvant. One immunizing dose is 2 cm3. In the course of the study, it was found that the survival of piglets obtained from vaccinated sows is 97.16%, which is comparable with the same indicator in the group of animals immunized with the reference drug - 96.96%. Despite the fact that the average weight of piglets in the experimental group on the 45th day of life was 130 g less than of those in the control group, by the 180th day of life, the experimental piglets were 4.33 kg heavier than the animals in the control group. The average daily gain in the experimental group was 33 g more than the one in the control group. Thus, the selected antigenic composition for the inactivated vaccine is optimal, and is capable of providing high immunogenic and protective activity, both in a vivarium and in an industrial pig-breeding enterprise.

Isolation, Antimicrobial Resistance Phenotypes, and Virulence Genes of Bordetella bronchiseptica From Pigs in China, 2018-2020

Bordetella bronchiseptica is a leading cause of respiratory diseases in pigs. However, epidemiological data of B. bronchiseptica in pigs particularly in China, the largest pig rearing country in the world is still limited. We isolated 181 B. bronchiseptica strains from 4259 lung samples of dead pigs with respiratory diseases in 14 provinces in China from 2018 to 2020. The average isolation rate of this 3-year period was 4.25% (181/4259). Antimicrobial susceptibility testing performed by disc diffusion method revealed that most of the B. bronchiseptica isolates in this study were resistant to ampicillin (83.98%), while a proportion of isolates were resistant to cefotaxime (30.39%%), chloramphenicol (12.71%), gentamicin (11.60%), florfenicol (11.60%), tetracycline (8.84%), amoxicillin (8.29%), tobramycin (6.63%), ceftriaxone (4.97%), and cefepime (0.55%). There were no isolates with resistant phenotypes to imipenem, meropenem, polymyxin B, ciprofloxacin, enrofloxacin, and amikacin. In addition, ~13.18% of the isolates showed phenotypes of multidrug resistance. Detection of antimicrobial resistance genes (ARGs) by PCR showed that 16.57% of the B. bronchiseptica isolates in this study was positive to aac(3)-IV, while 3.87%, 2.21%, 1.10%, 0.55%, 0.55%, and 0.55% of the isolates were positive to aac6'-Ib, rmtA, bla_TEM, bla_SHV, oqxB, and tetA, respectively. Detection of virulence factors encoding genes (VFGs) by conventional PCR showed that over 90% of the pig B. bronchiseptica isolates in this study were positive to the five VFGs examined (fhaB, 97.24%; prn, 91.16%; cyaA, 98.34%; dnt, 98.34%; betA, 92.82%). These results demonstrate B. bronchiseptica as an important pathogen associated with pig respiratory disorders in China. The present work contributes to the current understanding of the prevalence, antimicrobial resistance and virulence genes of B. bronchiseptica in pigs.

Comparison of oral, nebulized and combination antibiotic treatment of Bordetella bronchiseptica in baboons (Papio spp.)

Incidence of Bordetella pertussis, the causative agent of whooping cough, is rising in some global human populations despite high vaccination rates, and significant research is underway to address the issue. Baboons are an established model for pertussis research, but like many mammals, they can be naturally infected with Bordetella bronchiseptica. Because B. bronchiseptica interferes with B. pertussis research, it must be excluded from baboons under consideration for enrollment in pertussis studies. In addition to research-related concerns, B. bronchiseptica can sometimes cause clinical disease in baboons and other nonhuman primates. This study examined the use of antibiotics to clear B. bronchiseptica in naturally infected baboons. Thirty-five juvenile baboons were divided into five treatment groups: oral sulfamethoxazole/trimethoprim (TMS), nebulized gentamicin (gentamicin), combination (TMS + gentamicin) in positive animals, combination (TMS + gentamicin) as a prophylactic in exposed animals and no treatment (control). Combination of oral TMS and nebulized gentamicin given to positive animals was most effective, producing long-term clearance in 11 out of 12 treated animals. To avoid unnecessary use of antibiotics, our primary management strategy is screening and separating to allow natural clearance and limiting exposure to non-infected animals, but this study investigates an antibiotic regimen that could be used in special circumstances.

A proposed scheme for the monitoring of antibiotic resistance in veterinary pathogens of food animals in the UK

BACKGROUND

Antibiotic resistance in bacteria is a global threat to both animal and public health, and detecting its occurrence is an important component of control strategies. Monitoring programmes for antibiotic resistance are currently in place in food-producing animals in the European Union covering the zoonotic bacteria Salmonella enterica, Campylobacter coli and Campylobacter jejuni and the indicator bacteria Escherichia coli, Enterococcus faecalis and Enterococcus faecium. However, there is no equivalent pan-European statutory monitoring programme covering the antibiotic susceptibility of veterinary bacterial pathogens in food animals. This paper considers that issue and aims to facilitate and stimulate further discussion.

METHODS

Recommendations, proposed by the authors from the scientific literature and following expert discussion at international meetings, are presented for monitoring the susceptibility of key veterinary pathogens.

RESULTS

The selected veterinary pathogens comprise Actinobacillus pleuropneumoniae, Bordetella bronchiseptica, E. coli, Histophilus somni, Mannheimia haemolytica, Pasteurella multocida, Staphylococcus aureus and Streptococcus spp. from the major food animal species cattle, pigs and poultry. The organisms are tested using harmonised panels of antibiotics over specified dilution ranges in a broth microdilution method.

CONCLUSION

The selected antibiotics and their respective dilution ranges are presented together with the underlying rationale for inclusion; the ranges chosen are suitable for incorporation into three microtitre plates, with each organism tested using a single plate. The recommendations are being implemented in 2020 in the UK for monitoring of the susceptibility of veterinary bacterial pathogens.

Eight years of sales surveillance of antimicrobials for veterinary use in Germany-What are the perceptions?

A surveillance system for sales volumes of antimicrobial agents for veterinary use was established in Germany in 2011. Since then, pharmaceutical companies and wholesalers have been legally obliged to report annual volumes of veterinary antimicrobial products sold to veterinary practices or clinics located in Germany. The evaluation of sales volumes for eight consecutive years resulted in a considerable total decrease by 58% from 1706 tons to 722 tons. During the investigation period, two legally binding measures to control the risk of antimicrobial resistance resulting from the veterinary use of antimicrobials were introduced, a) the German treatment frequencies benchmarking in 2014 and b) the obligation to conduct susceptibility testing for the use of cephalosporins of the 3^rd and 4^th generation and of fluoroquinolones in 2018. Both had a marked impact on sales volumes. Nonetheless, the category of Critically Important Antimicrobials as defined by the World Health Organization kept accounting for the highest share on sales volumes in Germany in 2018 with 403 tons, despite an overall reduction by 53%. Sales surveillance is considered essential for data retrieval on a global scale and inter-country comparison. However, the usability of a surveillance system based on sales data for risk management of antimicrobial resistance has limitations. The German system does not include off-label use of antimicrobial products authorized for human medicine and does not allow for identification of areas of high risk according to animal species, farm and production types and indications for treatment. For further reduction and enhanced promotion of a prudent use of antimicrobials, targeted measures would be required that could only be deducted from use data collected at farm or veterinary practice level. A surveillance system based on use data is currently lacking in Germany but will be established according to Regulation (EU) 2019/6 on veterinary medicinal products.

Comparative genomic analysis of Bordetella bronchiseptica isolates from the lungs of pigs with porcine respiratory disease complex (PRDC)

BACKGROUND

Bordetella bronchiseptica (B. bronchiseptica), as an opportunistic pathogen, can cause respiratory diseases in a variety of animals, including humans. In additional to being involved in porcine atrophic rhinitis through coinfection with Pasteurella multocida, B. bronchiseptica is associated with porcine respiratory disease complex (PRDC). While there are genomic data available from different host species, little is known about B. bronchiseptica isolates from pig lungs, especially from lungs characterized as having PRDC.

RESULTS

A total of five B. bronchiseptica isolates were identified from pig lungs characterized as PRDC. The draft genomes of these strains were generated. In comparison with the other reported genomes, these five isolates showed the similar general characteristic including G+C content, rRNAs/tRNA, and clusters of orthologous groups of proteins (COGs). Phylogenetic analysis of all B. Bronchiseptica isolates of different species available at GenBank based on core genome multilocus sequence typing (cgMLST) classified them into two genogroups. All five isolates from this study, with the other isolates from pigs, were placed into a subclade of genogroup I consisting of only mammalian isolates. By contrast, genogroup II contained the isolates from an avian species (turkey) and some mammals (human and dog). Moreover, genome annotation revealed the presence of antibiotic resistance genes and virulence genes among these five genomes, consistent with the similarity and variety in genomic traits. Finally, comparative analysis of insertion sequence (IS) and prophages in five genomes further showed the similarity and variety in genomic characteristic.

CONCLUSIONS

This is the first study to provide comparative genomics of B. bronchiseptica strains from pig lungs characterized as having PRDC. Importantly, the findings presented in this study reveal novel genomic characteristic of B. bronchiseptica, which should provide insightful information on genome evolution.

Characterization of a Unique Bordetella bronchiseptica vB_BbrP_BB8 Bacteriophage and Its Application as an Antibacterial Agent

Bordetella bronchiseptica, an emerging zoonotic pathogen, infects a broad range of mammalian hosts. B. bronchiseptica-associated atrophic rhinitis incurs substantial losses to the pig breeding industry. The true burden of human disease caused by B. bronchiseptica is unknown, but it has been postulated that some hypervirulent B. bronchiseptica isolates may be responsible for undiagnosed respiratory infections in humans. B. bronchiseptica was shown to acquire antibiotic resistance genes from other bacterial genera, especially Escherichia coli. Here, we present a new B. bronchiseptica lytic bacteriophage—vB_BbrP_BB8—of the Podoviridae family, which offers a safe alternative to antibiotic treatment of B. bronchiseptica infections. We explored the phage at the level of genome, physiology, morphology, and infection kinetics. Its therapeutic potential was investigated in biofilms and in an in vivoGalleria mellonella model, both of which mimic the natural environment of infection. The BB8 is a unique phage with a genome structure resembling that of T7-like phages. Its latent period is 75 ± 5 min and its burst size is 88 ± 10 phages. The BB8 infection causes complete lysis of B. bronchiseptica cultures irrespective of the MOI used. The phage efficiently removes bacterial biofilm and prevents the lethality induced by B. bronchiseptica in G. mellonella honeycomb moth larvae.

Polyamino-Isoprenyl Derivatives as Antibiotic Adjuvants and Motility Inhibitors for Bordetella bronchiseptica Porcine Pulmonary Infection Treatment

The spreading of multidrug-resistant bacteria and the lack of novel antibiotic molecules leave clinicians and veterinarians with very limited options to treat bacterial infections, especially those caused by Gram-negative pathogens. To reduce the selection of antibiotic resistance mechanisms and their transfer to human pathogens, veterinary pharmaceutical companies have dramatically decreased the number of antibiotics used. Among all the investigated alternate solutions, chemosensitizers, which decrease the amount of the used drugs, appear to be one of the most promising strategies. In this study, we reported that polyamino-isoprenyl derivatives can potentiate florfenicol activity against veterinary sensitive reference strains as well as clinical isolates. These molecules induce inner membrane depolarization and subsequently inhibit efflux pumps by collapsing the proton-motive force (PMF). Considering that Bordetella bronchiseptica rotor flagellum is highly PMF dependent and that flagellar motility represents an important factor involved in colonization, we monitored the swimming and swarming motilities of bacteria and showed a strong inhibition in the presence of the lead selected compound. Taken together, our results suggest that this class of molecules are able to increase treatment efficacy and decrease drug consumption.