Routine antibiotic therapy in dogs increases the detection of antimicrobial-resistant faecal Escherichia coli.

Background: Antimicrobial resistance (AMR) is a critical health problem, with systemic antimicrobial therapy driving development of AMR across the host spectrum. Objectives: This study compares longitudinal carriage, at multiple timepoints, of AMR faecal Escherichia coli in dogs undergoing routine antimicrobial treatment. Methods: Faecal samples (n = 457) from dogs (n = 127) were examined pretreatment, immediately after treatment and 1 month and 3 months post-treatment with one of five antimicrobials. Isolates were tested for susceptibility to a range of antimicrobials using disc diffusion for each treatment group at different timepoints; the presence/absence of corresponding resistance genes was investigated using PCR assays. The impact of treatment group/timepoint and other risk factors on the presence of resistance [MDR, fluoroquinolone resistance, third-generation cephalosporin resistance (3GCR) and ESBL and AmpC production] was investigated using multilevel modelling. Samples with at least one AMR E. coli from selective/non-selective agar were classed as positive. Resistance was also assessed at the isolate level, determining the abundance of AMR from non-selective culture. Results: Treatment with ß-lactams or fluoroquinolones was significantly associated with the detection of 3GCR, AmpC-producing, MDR and/or fluoroquinolone-resistant E. coli, but not ESBL-producing E. coli, immediately after treatment. However, 1 month post-treatment, only amoxicillin/clavulanate was significantly associated with the detection of 3GCR; there was no significant difference at 3 months post-treatment for any antimicrobial compared with pretreatment samples. Conclusions: Our findings demonstrated that ß-lactam and fluoroquinolone antibiotic usage is associated with increased detection of important phenotypic and genotypic AMR faecal E. coli following routine therapy in vet-visiting dogs. This has important implications for veterinary and public health in terms of antimicrobial prescribing and biosecurity protocols, and dog waste disposal.

Impact of systemic antimicrobial therapy on mucosal staphylococci in a population of dogs in Northwest England.

BACKGROUND: Antimicrobial-resistant bacteria are increasingly isolated from veterinary patients. OBJECTIVES: To determine risk factors for antimicrobial resistance (AMR) among canine mucosal staphylococci following routine antimicrobial treatment with cefalexin (CFX), clavulanate-amoxicillin (AC), cefovecin (CVN), clindamycin (CD) or a fluoroquinolone (FQ). ANIMALS: Mucosal swab samples (n = 463) were collected from 127 dogs pre-treatment, immediately, and at one- and three-months post-treatment. METHODS: Staphylococci were identified phenotypically and biochemically as coagulase negative (CoNS) or coagulase positive (CoPS); CoPS were speciated by nuc gene PCR. Antimicrobial susceptibility was determined using disc diffusion and mecA gene carriage by PCR. Multilevel, multivariable models examined associations between risk factors and presence/absence of CoPS, meticillin resistance (MR), multidrug-resistance (MDR) and fluoroquinolone resistance (FQR). RESULTS: The percentage of samples with CoNS increased and with CoPS (including S. pseudintermedius) decreased immediately post-treatment with CFX, CVN and CD (P ≤ 0.001) and one month post-treatment with CD (P = 0.003). By three months post-treatment, there was no significant difference compared to pre-treatment samples. Immediately post-treatment with FQs there was significantly increased risk of isolating MRS (P = 0.002), MDR (P = 0.002) or FQR (P = 0.013) staphylococci and of MDR following CFX treatment (P = 0.019). The percentage of samples with AMR staphylococci declined from immediately to three months post-treatment and there was no significant difference between resistance prevalence at one or three months post-treatment for most AMR traits and treatment groups. Exceptions include increased MDR following FQ (P = 0.048) or CFX (P = 0.021), at one and three months post-treatment, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: Systemic antimicrobials impact on mucosal staphylococci. Immediately after therapy, the mucosa may be a reservoir for AMR staphylococci that are a source of mobile genetic elements carrying AMR genes.

Cross-reaction and co-sensitization among related and unrelated allergens in canine intradermal tests.

BACKGROUND: Intradermal tests are used to identify allergens for avoidance and immunotherapy in atopic dogs. HYPOTHESIS/OBJECTIVES: To evaluate cross-reaction or co-sensitization among 53 intradermal test allergens. ANIMALS: Six hundred and fifty-one client-owned dogs with atopic dermatitis. METHODS: Intradermal tests were performed with 53 house dust/storage mite, epidermal, insect, tree, weed and grass pollen and mould allergens. Pairwise comparisons were used to calculate the odds ratios (ORs), 95% confidence intervals (CIs) and statistical significance for the results of each allergen pair, with significance at P < 0.0006 (Holm-Bonferroni correction to reduce the false-detection rate). RESULTS: Apart from cotton, cockroach, red clover, grain smut and Penicillium, the results for the allergens within each group were statistically associated [ORs from 4.7 (CI 2.5-8.9) to 1229.4 (CI 166.5-1795.1); P = 0.0005 to P < 0.0001]. Excluding red clover and cotton, 94% of results between tree, weed and grass pollens were also statistically associated [ORs from 8.3 (CI 3.6-24.7) to 117 (CI 29.1-341); P = 0.0005 to P < 0.0001]. In contrast, few allergens from unrelated groups were statistically associated [ORs from 0.12 (CI 0.03-1.1) to 27.7 (CI 0.2-93); P = 1.0 to P < 0.0001]. The mean (SD) of the log e transformed ORs for the related and statistically associated allergens [5.3 (1.3)] was significantly greater than those for related but nonstatistically associated [1.7 (1.6)] or unrelated allergens [1.4 (1.4); P < 0.0001]. CONCLUSIONS AND CLINICAL IMPORTANCE: This suggests that there is cross-reaction or co-sensitization between related allergens. This could have implications for allergen selection in testing and immunotherapy, but further studies are required to differentiate cross-reaction from co-sensitization.

Choosing the best antimicrobial for the job.

Tim Nuttall discusses some factors to consider when interpreting the results of antimicrobial susceptibility tests.

The glucocorticoid sparing efficacy of Phytopica in the management of canine atopic dermatitis.

This double-blind randomized placebo-controlled trial indicates that Phytopica can be an effective glucocorticoid sparing agent in canine atopic dermatitis (AD). Twenty-two dogs with perennial AD [Canine Atopic Dermatitis with Severity Index (CADESI-03) >or= 60] were given 200 mg/kg Phytopica or an identical placebo in food once daily for 56 days. All dogs were initially given 0.4 mg/kg methyl-prednisolone once daily, which was then adjusted according to the daily pruritus score (0-100 mm visual analogue scale). The cumulative dose and pruritus score were lower in the Phytopica than the placebo group. There were statistically significant time and treatment effects for the methyl-prednisolone dose and pruritus score, but there were no significant differences between the Phytopica and placebo groups in the proportion of dogs that achieved a > 50% reduction in dose or pruritus scores at day 56; the mean CADESI-03 scores at days 0, 28 and 56; the numbers achieving >50% reduction in CADESI-03 at days 28 and 56; or in the owners' global efficacy score at days 28 and 56. Adverse events included diarrhoea (three Phytopica and one placebo treated dog), polyuria/polydipsia (three dogs in each group), and polyphagia, intermittent anorexia and panting (one dog each in the placebo group). None of these by themselves required withdrawal of treatment.

Management of canine atopic dermatitis using the plant extract PYM00217: a randomized, double-blind, placebo-controlled clinical study.

This study evaluated PYM00217, a proprietary blend of plant extracts, in the management of canine atopic dermatitis (AD). One hundred and twenty dogs were diagnosed with perennial AD on the basis of history, clinical signs, a positive test for perennial allergens and elimination of other dermatoses. Exclusion criteria included antimicrobials within 7 days, antihistamines within 14 days, oral/topical glucocorticoids or ciclosporin within 28 days, and parenteral glucocorticoids, essential fatty acids or immunotherapy within 56 days. Flea control, shampoos and ear cleaners were permitted. Dogs with a minimum canine atopic dermatitis extent and severity index (CADESI) of 25 were randomly allocated to receive PYM00217 (100, 200 or 400 mg kg-1 day-1) or placebo for 12 weeks. The mean reductions in CADESI (intention-to-treat population) were 3.9% (placebo; n=29), 4.4% (100 mg kg-1 day-1; n=30), 23.4% (200 mg kg-1 day-1; n=29) and 8.5% (400 mg kg-1 day-1; n=29). The reduction in the 200 mg kg-1 day-1 group was significant (P<0.01). For dogs with a baseline CADESI>or=50, the mean changes were +10.6% (placebo; n=12), +0.6% (100 mg kg-1 day-1; n=14), -29.3% (200 mg kg-1 day-1; n=14) and -3.4% (400 mg kg-1 day-1; n=15). The 200 mg kg-1 day-1 dose was significantly more effective than placebo (P=0.038). No serious adverse effects were reported. Minor adverse effects seen in 10% (placebo and 100 mg kg-1 day-1), 24% (200 mg kg-1 day-1) and 42% (400 mg kg-1 day-1) of cases were mainly minor gastrointestinal disorders and only five cases required cessation of dosing. Two dogs (one in each of the 100 mg kg-1 day-1 and 200 mg kg-1 day-1 groups) refused to eat the medicated food. In conclusion, PYM00217 at 200 mg kg-1 appears to be an effective, palatable and well-tolerated treatment for canine AD.