Characterisation of extended-spectrum β-lactamase and AmpC β-lactamase-producing Enterobacteriaceae isolated from companion animals in New Zealand

<p>AIMS: To assess the occurrence of, and characterise, extended-spectrum β-lactamase (ESBL) and AmpC β-lactamase (AmpC)-producing Enterobacteriaceae isolated by veterinary diagnostic laboratories from infection sites in companion animals in New Zealand.</p> <p>METHODS: Selected Enterobacteriaceae isolates were submitted by seven New Zealand veterinary diagnostic laboratories. They were isolated from infection sites in companion animals between June 2012 and June 2013, and were resistant to amoxicillin-clavulanic acid, fluoroquinolones, or any combination of two or more antimicrobials. Based on disk diffusion test results, the isolates were phenotypically categorised according to production of ESBL and AmpC. Genes for ESBL and AmpC production were amplified by PCR and sequenced. <i>Escherichia coli</i> isolates were also typed by multilocus sequence typing.</p> <p>RESULTS: A total of 115 isolates matching the inclusion criteria were obtained from the participating laboratories, of which 74 (64%) originated from dogs and 29 (25%) from cats. Seven bacterial species were identified, of which <i>E. coli</i> was the most common (87/115, 76%). Of the 115 isolates, 10 (9%) expressed the ESBL phenotype, 43 (37%) the AmpC phenotype, and seven (6%) both ESBL and AmpC phenotypes. Of the 60 ESBL and AmpC-producing isolates, 36 (60%) were <i>E. coli</i>. Amongst these isolates, 27/60 (45%) were classified as multidrug resistant, compared with 15/55 (27%) non-ESBL or AmpC-producing isolates (p<0.01). Ninety five isolates were resistant to amoxicillin-clavulanic acid and 58 (61%) of these were ESBL or AmpC-producing. The predominant ESBL genes were <i>bla</i>_CTX-M-14 and <i>bla</i>_CTX-M-15, and the dominant plasmid-encoded AmpC gene was <i>bla</i>_CMY-2. Thirty-eight <i>E. coli</i> multilocus sequence types (ST) were identified, and the most prevalent were ST12 (12/89, 13%), ST131 (6/89, 7%) and ST648 (6/89, 7%). ESBL and AmpC-producing isolates accounted for 35/1,082 (3.2%) of the Enterobacteriaceae isolated by one laboratory network over the study period.</p> <p>CONCLUSIONS AND CLINICAL RELEVANCE: ESBL and AmpC-producing Enterobacteriaceae were associated with clinical infections in companion animals in New Zealand, and were often multidrug resistant. In this study, these organisms accounted for <5% of all Enterobacteriaceae isolated from infection sites by one laboratory network, but their prevalence among isolates resistant to amoxicillin-clavulanic acid was 61%. Therefore routine secondary testing for ESBL and AmpC production by Enterobacteriaceae that are resistant to amoxicillin-clavulanic acid in primary testing could improve the accuracy of definitive antimicrobial therapy in companion animals in New Zealand.</p

Characterisation of methicillin-resistant <i>Staphylococcus aureus</i> clinical isolates from animals in New Zealand, 2012–2013, and subclinical colonisation in dogs and cats in Auckland

<p>AIMS: To characterise methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) isolates from infection sites in animals in New Zealand and assess the prevalence of subclinical MRSA colonisation in dogs and cats attending veterinary clinics in Auckland.</p> <p>METHODS: MRSA isolates from clinical specimens obtained by the main New Zealand veterinary diagnostic laboratories between June 2012 and June 2013, were genotypically characterised by DNA microarray hybridisation analysis and <i>spa</i> typing. In addition, nasal or perineal skin swabs collected from a cross-sectional sample of dogs (n=361) and cats (n=225) attending 29 veterinary clinics in Auckland during the same period were analysed for MRSA by culture.</p> <p>RESULTS: Eight MRSA clinical isolates were submitted for characterisation by the participating laboratories. The isolates originated from five dogs, including two isolates from the same dog, one foal, and one isolate had no identification of the source. The strain-types identified were AK3 (ST-5 SCC<i>mec</i>IV t045; n=1), USA500 (ST8 SCC<i>mec</i>IV t064; n=1), WSPP (ST30 SCC<i>mec</i>IV t019; n=1), Rhine Hesse (ST5 SCC<i>mec</i>II t002; n=2), and EMRSA-15 (ST22 SCC<i>mec</i>IV t032; n=3). No MRSA were isolated from 586 cultured swabs. Methicillin-susceptible <i>S. aureus</i> were detected in 9/257 (3.5%) swabs and non-<i>aureus</i> staphylococci in 22/257 (8.5%) swabs. The estimated true MRSA subclinical colonisation prevalence was 0%, with an upper 95% CI boundary of 1.9% for cats and 1.4% for dogs.</p> <p>CONCLUSIONS: The modest number of MRSA isolates submitted for this study by the participating laboratories suggests clinical MRSA infection in animals in New Zealand continues to be sporadic. The wide variety of strain-types found mirrored the evolving strain-type diversity observed in humans. We cannot rule out bias due to the non-random sampling of dogs and cats, but the apparent colonisation prevalence of 0% was consistent with the low prevalence of subclinical colonisation in humans in New Zealand. These similarities indicate the epidemiology of animal and human MRSA infections are linked.</p> <p>CLINICAL RELEVANCE: In the last decade, the prevalence of human MRSA infections in New Zealand has steadily increased. This is the second published study of MRSA in animals in New Zealand. The results indicate clinical MRSA infection in animals remains sporadic, but the diversification of the strain-types may pose new therapeutic challenges to veterinarians, due to their diverse resistome.</p

Molecular typing of <i>Leptospira</i> spp. in farmed and wild mammals reveals new host-serovar associations in New Zealand

To apply molecular typing to DNA isolated from historical samples to determine Leptospira spp. infecting farmed and wild mammals in New Zealand. DNA samples used in this study were extracted from urine, serum or kidney samples (or Leptospira spp. cultures isolated from them) collected between 2007 and 2017 from a range of domestic and wildlife mammalian species as part of different research projects at Massey University. Samples were included in the study if they met one of three criteria: samples that tested positive with a lipL32 PCR for pathogenic Leptospira; samples that tested negative by lipL32 PCR but were recorded as positive to PCR for pathogenic Leptospira in the previous studies; or samples that were PCR-negative in all studies but were from animals with positive agglutination titres against serogroup Tarassovi. DNA samples were typed using PCR that targeted either the glmU or gyrB genetic loci. The resulting amplicons were sequenced and typed relative to reference sequences. We identified several associations between mammalian hosts and Leptospira strain/serovar that had not been previously reported in New Zealand. Leptospira borgpetersenii strain Pacifica was found in farmed red deer (Cervus elaphus) samples, L. borgpetersenii serovars Balcanica and Ballum were found in wild red deer samples, Leptospira interrogans serovar Copenhageni was found in stoats (Mustela erminea) and brushtail possums (Trichosurus vulpecula), and L. borgpetersenii was found in a ferret (Mustela putorius furo). Furthermore, we reconfirmed previously described associations including dairy cattle with L. interrogans serovars Copenhageni and Pomona and L. borgpetersenii serovars Ballum, Hardjo type bovis and strain Pacifica, sheep with L. interrogans serovar Pomona and L. borgpetersenii serovar Hardjo type bovis, brushtail possum with L. borgpetersenii serovar Balcanica, farmed deer with L. borgpetersenii serovar Hardjo type bovis and hedgehogs (Erinaceus europaeus) with L. borgpetersenii serovar Ballum. This study provides an updated summary of host–Leptospira associations in New Zealand and highlights the importance of molecular typing. Furthermore, strain Pacifica, which was first identified as Tarassovi using serological methods in dairy cattle in 2016, has circulated in animal communities since at least 2007 but remained undetected as serology is unable to distinguish the different genotypes. To date, leptospirosis in New Zealand has been diagnosed with serological typing, which is deficient in typing all strains in circulation. Molecular methods are necessary to accurately type strains of Leptospira spp. infecting mammals in New Zealand.</p

Seroprevalence and exposure to risk factors for leptospirosis among veterinary students at Massey University

<div><p>AIMS: To determine the seroprevalence and quantify putative risk factors for exposure to leptospirosis both within and outside the veterinary curriculum among undergraduate veterinary students at Massey University, New Zealand.</p><p>METHODS: A cross-sectional study was conducted from September 2010 to November 2011. In total, 302 students were blood sampled, with serum tested by microscopic agglutination test (MAT) for antibodies to <i>Leptospira borgpetersenii</i> serovars Hardjobovis, <i>Leptospira interrogans</i> Pomona and <i>Leptospira borgpetersenii</i> Ballum. Information on demographic characteristics, potential exposure within and outside the veterinary curriculum in the previous 18 months, and previous leptospirosis-like clinical history were recorded using an online questionnaire.</p><p>RESULTS: All students were MAT negative for each serovar, using a cut-point of ≥1:48. Potential exposure to animal urine within and outside the veterinary curriculum was reported by 259/302 (85.8%) and 150/302 (49.7%) of the students, respectively. The median number of potential exposures to animal urine by each student within the veterinary curriculum in the previous 18 months was 63 (min 1, max 155). The other potential exposures among respondents included home slaughter (63/302; 20.9%), hunting (43/302; 14.2%) and outdoor activities involving exposure to fresh water (241/302; 79.8%).</p><p>CONCLUSIONS: This study demonstrated that these veterinary students were at low risk of contracting leptospirosis, despite frequent exposure to potential sources of infection. The findings in this study contribute to a broader understanding of the occupational risk of leptospirosis. Data describe the level of animal exposure in veterinary students, which can support other zoonotic disease studies in this group.</p></div