Persistent Bordetella bronchiseptica infection in a child with cystic fibrosis: Relationship to bacterial phenotype

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.

Conquering the host: Bordetella spp. and Pseudomonas aeruginosa molecular regulators in lung infection

When bacteria sense cues from the host environment, stress responses are activated. Two component systems, sigma factors, small RNAs, ppGpp stringent response, and chaperones start coordinate the expression of virulence factors or immunomodulators to allow bacteria to respond. Although, some of these are well studied, such as the two-component systems, the contribution of other regulators, such as sigma factors or ppGpp, is increasingly gaining attention. Pseudomonas aeruginosa is the gold standard pathogen for studying the molecular mechanisms to sense and respond to environmental cues. Bordetella spp., on the other hand, is a microbial model for studying host-pathogen interactions at the molecular level. These two pathogens have the ability to colonize the lungs of patients with chronic diseases, suggesting that they have the potential to share a niche and interact. However, the molecular networks that facilitate adaptation of Bordetella spp. to cues are unclear. Here, we offer a side-by-side comparison of what is known about these diverse molecular mechanisms that bacteria utilize to counteract host immune responses, while highlighting the relatively unexplored interactions between them.

A doggy tale: Risk of zoonotic infection with Bordetella bronchiseptica for cystic fibrosis (CF) patients from live licenced bacterial veterinary vaccines for cats and dogs

WHAT IS KNOWN AND OBJECTIVE

Live-attenuated bacterial veterinary vaccines can constitute an infection risk for individuals with any defect in their phagocytic function, including chronic granulomatous disease, leukocyte adhesion deficiency, myeloperoxidase deficiency, as well as Chediak-Higashi syndrome, from accidental acquisition of licenced attenuated live bacterial vaccine, at vaccination or from their vaccinated pet. Ownership of small companion animals, including cats and dogs, is popular within the cystic fibrosis (CF) community. These animals require vaccines as part of their routine care, which may involve live viral and bacterial vaccines, with potential for infection in the CF owner. This report examines the scope of current canine and feline vaccines, with particular emphasis on veterinary vaccination strategies against the Gram-negative pathogen, Bordetella bronchiseptica and describes new vaccine innovations offering protection to both pet and CF owner.

COMMENT

The Gram-negative bacterium, Bordetella bronchoseptica, may cause respiratory disease in small companion animals, as well as in certain human vulnerable groups, including those with CF. Live licenced veterinary bacterial vaccines for Bordetella bronchiseptica (Kennel Cough) are available for cats and dogs, which are an infection concern for humans with CF who may come into contact with vaccinated animals. Live licenced veterinary bacterial vaccines for Bordetella bronchiseptica (Kennel Cough) are available for intranasal administration to cats and dogs. These vaccines require a withdrawal period of vaccinated animal from vulnerable owner, ranging from 35 days - 11 weeks. Recently, a new dead IM vaccine is now available not requiring exclusion of the vaccinated pet from CF owner.

WHAT IS NEW & CONCLUSION

CF pharmacists, hospital pharmacists and community pharmacists are important custodians of vaccine-related advice to people with CF, who are frequently consulted for such advice. Pharmacists should be aware of the recent innovations in veterinary medicines, so that they can give appropriate advice to people with CF when asked. Immunocompromised patients, that is those with CF or those with any defect in their phagocytic function (chronic granulomatous disease, leukocyte adhesion deficiency, myeloperoxidase deficiency, Chediak-Higashi syndrome) should avoid exposure to live veterinary bacterial vaccines and seek animal vaccination utilising non-live vaccines. Most importantly, this manuscript highlights the development of a new veterinary vaccine for dogs, which we want to make the CF healthcare community aware of, which is an acellular dead vaccine, so that those patients with dogs needing annual vaccination can select this vaccine pathway, thereby minimising risk of infection from the vaccine strains and avoiding the social exclusion between CF patient and their pet. CF patients should understand the potential infection implications of live-attenuated viral and bacterial strains as vaccines, whether these are small companion animals, exotic animals or large farm animals. Patients should make their veterinarian aware of their CF status, so that a safe and efficacious vaccine strategy is used, both mitigating the potential infection risks from live vaccine components with the CF patient, but simultaneously offering maximum immunological protection to the animal.

Rapidly progressive interstitial lung disease due to anti-melanoma differentiation associated protein-5 requiring a bilateral lung transplant, and complicated by kennel cough

The association between inflammatory myopathies anti-synthetase syndrome and interstitial lung disease has been recognized since the 1950s. Patients generally present with gradual onset of symptoms and slow progression of fibrosis over months to years. Herein, we describe a previously well 51-year-old man who presented with three months of progressive small joint arthritis, cough, dyspnea, and eventually hypoxemic respiratory failure following a viral prodrome. He continued to decompensate despite high dose corticosteroids and mycophenolate mofetil, ultimately requiring extracorporeal membranous oxygenation as a bridge to bilateral lung transplantation. Clinically amyopathic dermatomyositis (CADM) was confirmed through serum positivity for anti-Melanoma Differentiation Associated Protein-5 (MDA-5) antibody. Interestingly, his post-operative course was complicated by a zoonotic infection with Bordetella bronchiseptica. This case highlights the importance of identifying rare autoimmune diseases, and the utility of transfer to a lung transplant center.

Chronic Airway Colonization by Achromobacter xylosoxidans in Cystic Fibrosis Patients Is Not Sustained by Their Domestic Environment

Achromobacter spp. are nonfermentative Gram-negative bacilli considered emergent pathogens in cystic fibrosis (CF). Although some cross-transmission events between CF patients have been described, Achromobacter strains were mostly patient specific, suggesting sporadic acquisitions from nonhuman reservoirs. However, sources of these emergent CF pathogens remain unknown. A large collection of specimens (n = 273) was sampled in the homes of 3 CF patients chronically colonized by Achromobacter xylosoxidans with the aim of evaluating the potential role of domestic reservoirs in sustaining airway colonization of the patients. Samples were screened for the presence of Achromobacter by using genus-specific molecular detection. Species identification, multilocus genotypes, and antimicrobial susceptibility patterns observed for environmental isolates were compared with those of clinical strains. Patient homes hosted a high diversity of Achromobacter species (n = 7), including Achromobacter mucicolens and A. animicus, two species previously isolated from human samples only, and genotypes (n = 15), all showing an overall susceptibility to antimicrobial agents. Achromobacter strains were mostly isolated from indoor moist environments and siphons, which are potential reservoirs for several CF emerging pathogens. A. xylosoxidans, the worldwide prevalent species colonizing CF patients, was not the major Achromobacter species inhabiting domestic environments. A. xylosoxidans genotypes chronically colonizing the patients were not detected in their household environments. These results support the notions that the domestic environment could not be incriminated in sustained patient colonization and that after initial colonization, the environmental survival of A. xylosoxidans clones adapted to the CF airways is probably impaired.IMPORTANCE Achromobacter spp. are worldwide emerging opportunistic pathogens in CF patients, able to chronically colonize the respiratory tract. Apart from regular consultations at the hospital CF center, patients spend most of their time at home. Colonization from nonhuman sources has been suggested, but the presence of Achromobacter spp. in CF patients' homes has not been explored. The domestic environments of CF patients chronically colonized by Achromobacter, especially wet environments, host several opportunistic pathogens, including a large diversity of Achromobacter species and genotypes. However, Achromobacter genotypes colonizing the patients were not detected in their domestic environments, making it unlikely that a shuttle between environment and CF airways is involved in persisting colonization. This also suggests that once the bacteria have adapted to the respiratory tract, their survival in the domestic environment is presumably impaired. Nevertheless, measures for reducing domestic patient exposure should be targeted on evacuation drains, which are frequently contaminated by CF opportunistic pathogens.

Cystic Fibrosis Mice Develop Spontaneous Chronic Bordetella Airway Infections

Chronic pulmonary disease and infection is the primary cause of morbidity and mortality in people with cystic fibrosis (CF). Though Pseudomonas aeruginosa, is most commonly found in the airways of individuals with CF, there is increasing appreciation for the diversity of the CF microbiome, including other taxa such as Bordetella. Here we describe the identification and impact of Bordetella pseudohinzii infection in CF mice, which previously have not been thought to develop spontaneous airway infections. We determined that CF mice are more susceptible to the B. pseudohinzii infections, and less able to resolve the infection than non-CF mice. Moreover, in both CF and non-CF mice, B. pseudohinzii infections lead to markedly reduced respiratory rates and a CF-specific immune response. These results establish the CF mouse model as an important tool for the study of CF-relevant infection and highlight the potential contribution of Bordetella to CF clinical pathology.

Bordetella Adenylate Cyclase-Hemolysin Toxins

Adenylate cyclase-hemolysin toxin is secreted and produced by three classical species of the genus Bordetella: Bordetella pertussis, B. parapertussis and B. bronchiseptica. This toxin has several properties such as: (i) adenylate cyclase activity, enhanced after interaction with the eukaryotic protein, calmodulin; (ii) a pore-forming activity; (iii) an invasive activity. It plays an important role in the pathogenesis of these Bordetella species responsible for whooping cough in humans or persistent respiratory infections in mammals, by modulating host immune responses. In contrast with other Bordetella toxins or adhesins, lack of (or very low polymorphism) is observed in the structural gene encoding this toxin, supporting its importance as well as a potential role as a vaccine antigen against whooping cough. In this article, an overview of the investigations undertaken on this toxin is presented.