Antibiotic susceptibility of canine Bordetella bronchiseptica isolates

[Chronic rhinitis in dogs and cats - an overview of etiology, diagnostics and therapy]

Chronic rhinitis is one of the most common diseases of the upper respiratory tract in dogs and cats. A multifactorial etiology is likely in most patients. In cats in particular, it is assumed that chronic rhinitis is a consequence of a previous viral infection. Affected animals may show unilateral or bilateral serous to mucopurulent nasal discharge or epistaxis. The diagnosis is based on histopathological examination of nasal mucosal biopsies once other causes of chronic nasal problems such as neoplasia, fungal infections, dental disease, parasites, polyps, or foreign bodies have been ruled out. In some cases, chronic rhinitis may be aggravated secondarily by concomitant bacterial infections. In order to improve mucociliary clearance, nasal lavage, inhalation therapy, and mucolytic medications represent the fundament of long-term treatment. In addition, some patients respond to anti-inflammatory drugs such as corticosteroids or nonsteroidal anti-inflammatory drugs. The administration of antibiotics is currently being discussed controversially, and does not lead to complete resolution of the clinical signs.

Outbreak management of multidrug-resistant Bordetella bronchiseptica in 16 shelter-housed cats

CASE SERIES SUMMARY

This case series describes an outbreak of multidrug-resistant (MDR) Bordetella bronchiseptica in 16 shelter-housed cats with infectious respiratory disease. Four cats presented with acute dyspnea on the same day, each with a history of previous upper respiratory disease that had resolved with treatment. Early diagnostic testing and culture and sensitivity allowed for targeted antimicrobial therapy and environmental interventions. A case definition based on exposure and clinical signs identified 12 additional presumptive cases, including the likely index case. Comprehensive outbreak management included diagnostic testing, risk assessment, vaccination, use of isolation and quarantine, increased surveillance and review of biosecurity practices. The outbreak resolved in 26 days.

RELEVANCE AND NOVEL INFORMATION

Management of an MDR B bronchiseptica outbreak in shelter-housed cats has not been previously described. Along with standard population and environmental measures, early and appropriate use of necropsy, PCR and bacterial culture allowed rapid and appropriate use of effective, second-line antibiotics. Shelters are resource-challenged population centers. Veterinarians working in animal shelters can play an important role in helping to develop cost-efficient and effective antimicrobial stewardship practices for companion animal settings. Outbreak management expertise and funding for diagnostic testing, as well as application of the principles of antimicrobial stewardship, are essential components of shelter medicine practice.

Antimicrobial resistance profiles of bacteria associated with lower respiratory tract infections in cats and dogs in England

BACKGROUND

Bacterial lower respiratory tract infections (bLRTIs) are common and potentially life threatening in cats and dogs. Antibiotic treatment is often initiated before the diagnosis of bLRTI; therefore improved knowledge of the aetiology and antibiotic susceptibility patterns of these infections is essential to inform empiric antibiotic choices.

METHODS

A retrospective study of microbiological, cytological results and their drug susceptibilities from lower respiratory samples (n = 1989) processed in a UK commercial laboratory between 2002 and 2012 was carried out.

RESULTS

Thirty-nine per cent of feline samples and 50% of canine samples were positive for bacterial growth with most yielding a single organism (72 % and 69%, respectively). Bordetella bronchiseptica (20.2% from dogs and 2.3% from cats), Pasteurella spp. (23.2%, 31.8%), E. coli (16.2%, 13.6%) and Pseudomonas spp. (11.1%, 11.4%) were most frequently isolated from cytologically positive samples which contained intracellular bacteria (10%, 14%). Amoxycillin-clavulanate, cephalothin, cefovecin, oxytetracycline and trimethoprim/sulfamethoxazole showed modest in vitro activity against E. coli from dogs (approximately 70% susceptibility). Pseudomonas spp. were resistant to enrofloxacin (50%), ticarcillin (25%) and marbofloxacin (13%) but showed lower or zero resistance to aminoglycosides (approximately 7%) and ciprofloxacin (0%). Multi drug resistance (acquired resistance to three or more antimicrobial drug classes) was particularly common among E. coli isolates, with 23% from feline samples and 43% from canine samples.

CONCLUSION

Resistance to certain first-choice antibiotics was detected in bLRTIs highlighting the need for continued monitoring and sound evidence to inform decision-making in the management of these infections.

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.

Survey of antimicrobial susceptibility of bacterial pathogens isolated from dogs and cats with respiratory tract infections in Europe: ComPath results

AIMS

To present antimicrobial susceptibilities for bacteria from dogs and cats with respiratory tract infection (RTI) across Europe in 2013-2014 and compare with data from 2008-2010.

METHODS AND RESULTS

Minimal inhibitory concentrations were determined for 464 isolates following Clinical and Laboratory Standards Institute standards using antibiotics approved for RTI treatment. Where possible, susceptibility was calculated using predominantly human-derived breakpoints whilst some antibiotics had no breakpoints. The main pathogen from dogs was Staphylococcus pseudintermedius which was > 90% susceptible to fluoroquinolones and oxacillin (92·5%; six isolates confirmed mecA-positive) and 53·8, 80·0 and 88·8% susceptible to tetracycline, penicillin and trimethoprim/sulfamethoxazole. Streptococci, Escherichia coli, Bordetella bronchiseptica, Staphylococcus aureus and Pseudomonas aeruginosa were also present in dog RTI. Streptococci were fully susceptible to penicillin, ampicillin and pradofloxacin. None were enrofloxacin-resistant but 31·4% had intermediate susceptibility. The least active agent against streptococci was tetracycline (51·4% susceptible). For E. coli, 90·9% were amoxicillin/clavulanic acid-susceptible; susceptibility to other compounds ranged from 63·6 to 81·8%. There are no breakpoints for B. bronchiseptica and Ps. aeruginosa. For Staph. aureus, penicillin susceptibility was low (34·8%); for other compounds 87·0-100%. The main RTI pathogen from cats was Pasteurella multocida, where only pradofloxacin has breakpoints (100% susceptible). Susceptibility of coagulase-negative staphylococci ranged from 66·7% (penicillin) to 97·2% (pradofloxacin). Streptococci from cats were 100% susceptible to all antibiotics except enrofloxacin and tetracycline (both 65·2% susceptible).

CONCLUSIONS

Overall, antimicrobial resistance was low to medium in RTI in dogs and cats, although susceptibility varied widely among pathogens studied.

SIGNIFICANCE AND IMPACT OF THE STUDY

Responsible use of antibiotics is crucial to maintain susceptibility and continued resistance monitoring is important to support this goal. These findings support the need for the setting of RTI-specific breakpoints for pathogens of dogs and cats.

Bacterial Diseases

Common marmosets are susceptible to a number of bacterial infections, which may be enzootic, causing sporadic but occasionally severe disease, or which may result in epizootics associated with more severe colony morbidity and mortality. The spectrum of these diseases often differs from those observed in macaque species, and veterinarians caring for common marmosets need to be aware of these unique susceptibilities. In formulating differential diagnoses for sick or diseased animals, it should be recognized that diseases once common in imported animals in the 1960s and 1970s are now rare. It is also important to recognize that housing and sanitation conditions can influence exposure to potentially pathogenic bacteria. In a zoological setting where mixed- or free-ranging exhibits are utilized, animals may be exposed to many more potential pathogens than would be the case in animals raised in a barrier facility.

Antimicrobial Resistance in Bordetella bronchiseptica

Bordetella bronchiseptica is involved in respiratory tract infections mainly in dogs and pigs but may also cause infections in humans. Valid and representative data on antimicrobial susceptibility of B. bronchiseptica is rare. Approved antimicrobial susceptibility testing methods have been published, but very few clinical breakpoints are available. The MIC values are low for most agents but high for β-lactam antibiotics and macrolides. Information on the genetic basis of resistance is scarce. For a small number of isolates that are resistant or show elevated MICs, the molecular basis of resistance was identified. Three tetracycline resistance genes, tet(A), tet(C), and tet(31), coding for major facilitator superfamily efflux pumps, were identified. Two other major facilitator superfamily exporter genes confer resistance to chloramphenicol (cmlB1) or to chloramphenicol and florfenicol (floR). Two class B chloramphenicol acetyltransferase genes (catB1 and catB3), which confer resistance to nonfluorinated phenicols by enzymatic inactivation, have been identified in B. bronchiseptica. Like the trimethoprim resistance genes dfrA1 and dfrB1, which code for trimethoprim-insensitive dihydrofolate reductases, the genes catB1 and catB3 were located on gene cassettes and found in class 1 integrons also harboring the sulfonamide resistance gene sul1. In addition, the gene sul2 has also been detected. Both sul1 and sul2 code for sulfonamide-insensitive dihydropteroate synthases. A gene cassette harboring the β-lactamase gene blaOXA-2 was also identified, whereas β-lactam resistance in B. bronchiseptica seems to be more likely due to reduced influx in combination with the species-specific β-lactamase encoded by blaBOR-1. The resistance genes were mostly located on conjugative plasmids.

Antimicrobial use Guidelines for Treatment of Respiratory Tract Disease in Dogs and Cats: Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases

Respiratory tract disease can be associated with primary or secondary bacterial infections in dogs and cats and is a common reason for use and potential misuse, improper use, and overuse of antimicrobials. There is a lack of comprehensive treatment guidelines such as those that are available for human medicine. Accordingly, the International Society for Companion Animal Infectious Diseases convened a Working Group of clinical microbiologists, pharmacologists, and internists to share experiences, examine scientific data, review clinical trials, and develop these guidelines to assist veterinarians in making antimicrobial treatment choices for use in the management of bacterial respiratory diseases in dogs and cats.

Comparative pharmacokinetics of a new oral long-acting formulation of doxycycline hyclate: A canine clinical trial

Doxycicline is used in dogs as treatment of several bacterial infections, mycoplasma, chlamydia and rickettsial diseases. However, it requires long treatments and several doses to be effective. The aim of this study was to determine the pharmacokinetics of four formulations of doxycycline hyclate, administered orally, with different proportions of excipients, acrylic acid-polymethacrylate-based matrices, to obtain longer therapeutic levels than conventional formulation. Forty-eight dogs were randomly assigned in five groups to receive a single oral dose (20mg/kg) of doxycycline hyclate without excipients (control) or a long-acting formulation containing doxycycline, acrylic acid polymer, and polymethacrylate in one of the following four proportions: DOX1(1:0.25:0.0035), DOX2(1:0.5:0.0075), DOX3 (1:1:0.015), or DOX4(1:2:0.0225). Temporal profiles of serum concentrations were obtained at several intervals after each treatment. Therapeutic concentrations were observed for 60h for DOX1 and DOX4, 48h for DOX2 and DOX3 and only 24h for DOX-C. None of the pharmacokinetic parameter differed significantly between DOX1 and DOX2 or between DOX3 and DOX4; however, the findings for the control treatment were significantly different compared to all four long-acting formulations. Results indicated that DOX1 had the most adequate pharmacokinetic-pharmacodynamic relationships for a time-dependent drug and had longer release times than did doxycycline alone. However, all four formulations can be effective depend on the minimum effective serum doxycycline concentration of the microorganism being treated. These results suggest that the use of any of these formulations can reduce the frequency of administration, the patient's stress, occurrence of adverse effects and the cost of treatment.

Pharmacokinetics of an oral extended-release formulation of doxycycline hyclate containing acrylic acid and polymethacrylate in dogs

OBJECTIVE

To determine the pharmacokinetics of doxycycline hyclate administered orally in the form of experimental formulations with different proportions of acrylic acid-polymethacrylate-based matrices.

ANIMALS

30 healthy adult dogs.

PROCEDURES

In a crossover study, dogs were randomly assigned (in groups of 10) to receive a single oral dose (20 mg/kg) of doxycycline hyclate without excipients (control) or extended-release formulations (ERFs) containing doxycycline, acrylic acid polymer, and polymethacrylate in the following proportions: 1:0.5:0.0075 (ERF1) or 1:1:0.015 (ERF2). Serum concentrations of doxycycline were determined for pharmacokinetic analysis before and at several intervals after each treatment.

RESULTS

Following oral administration to the study dogs, each ERF resulted in therapeutic serum doxycycline concentrations for 48 hours, whereas the control treatment resulted in therapeutic serum doxycycline concentrations for only 24 hours. All pharmacokinetic parameters for ERF1 and ERF2 were significantly different; however, findings for ERF1 did not differ significantly from those for the control treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that both ERFs containing doxycycline, acrylic acid polymer, and polymethacrylate had an adequate pharmacokinetic-pharmacodynamic relationship for a time-dependent drug and a longer release time than doxycycline alone following oral administration in dogs. Given the minimum effective serum doxycycline concentration of 0.26 μg/mL, a dose interval of 48 hours can be achieved for each tested ERF. This minimum inhibitory concentration has the potential to be effective against several susceptible bacteria involved in important infections in dogs. Treatment of dogs with either ERF may have several benefits over treatment with doxycycline alone.

Antimicrobial Susceptibility of Bordetella bronchiseptica Isolates from Swine and Companion Animals and Detection of Resistance Genes

Bordetella bronchiseptica causes infections of the respiratory tract in swine and other mammals and is a precursor for secondary infections with Pasteurella multocida. Treatment of B. bronchiseptica infections is conducted primarily with antimicrobial agents. Therefore it is essential to get an overview of the susceptibility status of these bacteria. The aim of this study was to comparatively analyse broth microdilution susceptibility testing according to CLSI recommendations with an incubation time of 16 to 20 hours and a longer incubation time of 24 hours, as recently proposed to obtain more homogenous MICs. Susceptibility testing against a panel of 22 antimicrobial agents and two fixed combinations was performed with 107 porcine isolates from different farms and regions in Germany and 43 isolates obtained from companion animals in Germany and other European countries. Isolates with increased MICs were investigated by PCR assays for the presence of resistance genes. For ampicillin, all 107 porcine isolates were classified as resistant, whereas only a single isolate was resistant to florfenicol. All isolates obtained from companion animals showed elevated MICs for β-lactam antibiotics and demonstrated an overall low susceptibility to cephalosporines. Extension of the incubation time resulted in 1-2 dilution steps higher MIC50 values of porcine isolates for seven antimicrobial agents tested, while isolates from companion animals exhibited twofold higher MIC50/90 values only for tetracycline and cefotaxime. For three antimicrobial agents, lower MIC50 and MIC90 values were detected for both, porcine and companion animal isolates. Among the 150 isolates tested, the resistance genes blaBOR-1 (n = 147), blaOXA-2, (n = 4), strA and strB (n = 17), sul1 (n = 10), sul2 (n = 73), dfrA7 (n = 3) and tet(A) (n = 8) were detected and a plasmid localisation was identified for several of the resistance genes.

Development and characterization of attenuated metabolic mutants of Bordetella bronchiseptica for applications in vaccinology

Bordetella bronchiseptica is an important pathogen causing a number of veterinary respiratory syndromes in agriculturally important and food-producing confinement-reared animals, resulting in great economic losses annually amounting to billions of euros worldwide. Currently available live vaccines are incompletely satisfactory in terms of efficacy and safety. An efficient vaccine for livestock animals would allow reducing the application of antibiotics, thereby preventing the massive release of pharmaceuticals into the environment. Here, we describe two new potential vaccine strains based on the BB7865 strain. Two independent attenuating mutations were incorporated by homologous recombination in order to make negligible the risk of recombination and subsequent reversion to the virulent phenotype. The mutations are critical for bacterial metabolism, resistance to oxidative stress, intracellular survival and in vivo persistence. The resulting double mutants BB7865 risA aroA and BB7865 risA dapE were characterized as promising vaccine candidates, which are able to confer protection against colonization of the lower respiratory tract after sublethal challenge with the wild-type strain.

Antimicrobial susceptibility of Bordetella bronchiseptica isolates from porcine respiratory tract infections

MICs for 349 Bordetella bronchiseptica isolates from respiratory tract infections of swine were determined by broth microdilution. The lowest MIC at which 90% of isolates tested are inhibited (MIC90) was that of tetracycline and enrofloxacin (0.5 microg/ml), whereas the highest MIC90s were those of tilmicosin and cephalothin (32 microg/ml) as well as streptomycin (256 microg/ml).

Respiratory pharmacotherapy in emergency and critical care medicine

Successful pharmacologic management of most respiratory diseases is possible. All moderately to severely affected animals benefit from rest and supplemental oxygen. Careful identification of the underlying cause as well as an understanding of the pathophysiology behind various diseases is essential to successful patient outcome.

Molecular epidemiology of feline bordetellosis in two animal shelters in California, USA

"Kennel cough" in dogs in animal shelters is readily transmissible, reduces adoption rates, and commonly leads to the euthanasia of affected dogs. In cats, tracheobronchitis, conjunctivitis, and pneumonia have been associated with Bordetella bronchiseptica infection-but most cases of upper-respiratory infection (URI) probably are caused by herpesvirus and calicivirus, and many B. bronchiseptica culture-positive cats are clinically normal. Our prospective observational study was undertaken to document the contribution of B. bronchiseptica to disease in cats and dogs from two animal shelters undergoing outbreaks of canine kennel cough, to evaluate whether cross-species transmission might have occurred, and to determine if the presence of infected cats represented a risk to dogs. Clinically defined cases of kennel cough in dogs and URI in cats were investigated in two shelters by calculating clinical-disease incidence, alveolar-lavage cytological examination, bacterial and viral cultures, antibiotic-susceptibility testing, and molecular fingerprinting by pulsed-field gel electrophoresis. In a 40-cat and 40-dog "no-kill" shelter, the prevalences of culture positivity were 47% for B. bronchiseptica and 36% for calicivirus at the same time as two resident dogs demonstrated clinical cough. When no dogs had kennel cough 3 months later, 10% of cats were B. bronchiseptica-culture-positive and 63% calicivirus positive. In a large traditional shelter, the incidence of kennel cough in dogs increased over 12 weeks to a maximum of 19 cases/week/120 dogs, during which time the culture prevalence was 23% for B. bronchiseptica in dogs and 47% in cats. Three to 6 months before the kennel-cough epidemic, no dogs or cats were B. bronchiseptica positive. Very little genetic variability was detected in isolates from these shelters; all isolates except one corresponded to a single strain type which was identical to the pattern in a vaccine used in these shelters. Isolates from other cats, a horse, a llama, and a sea otter were genetically distinct from the shelter isolates. There was widespread resistance to cephalosporins and ampicillin, but low or no resistance to amoxicillin/clavulanate, trimethoprim-sulfamethoxazole, tetracycline, and enrofloxacin. Greater percent resistance was observed in the traditional shelter than in the no-kill shelter and feline isolates were more likely to be resistant than canine isolates.

Why is anti-microbial resistance a veterinary problem as well?

Resistance to anti-microbial agents has become one of the main issues in public health strategies world-wide. Much attention has been paid to the emergence of pathogenic micro-organisms such as enterococci or Salmonella that have developed resistance mechanisms that render them almost untreatable with current antibiotics. One of the alleged reasons for such an emergence is the non-medical use of antibiotics, especially in animals. However, only recently have veterinary forums and journals begun to discuss this topic. On the other hand, anti-microbial resistance has also become a problem in veterinary medicine and the number of reports indicating high rates of resistance among animal-originated micro-organisms is considerable. The present review deals with the mechanisms of resistance known for antibiotics in common veterinary use, the problem of anti-microbial resistance in veterinary medicine and the links between the use of antibiotics in animals and the emergence of anti-microbial resistance in humans.