Antimicrobial susceptibility of bacteria isolated from neonatal foal samples submitted to a New Zealand veterinary pathology laboratory (2004 to 2013).

AIMS: To describe antimicrobial susceptibility, and identify antimicrobial resistance (AMR), in bacteria isolated from New Zealand foals. METHODS: A database search was performed of submissions to a veterinary pathology laboratory between April 2004 and December 2013 for bacterial culture of samples from foals <3 weeks of age. Culture and susceptibility results were compiled with demographic information. Susceptibility results were as defined for the Kirby-Bauer disk diffusion susceptibility test based on Clinical Laboratory Standards Institute guidelines. Multi-drug resistance (MDR) was defined as non-susceptibility to ≥3 of a panel of antimicrobials (ceftiofur, enrofloxaxin, gentamicin, penicillin, tetracycline, trimethoprim-sulfonamide); penicillin susceptibility was not included for Gram-negative isolates. RESULTS: Submissions from 102 foals were examined, and 127 bacterial isolates were cultured from 64 (63%) foals. Of the 127 isolates, 32 (25%) were Streptococcus spp., 30 (24%) were Staphylococcus spp., 12 (10%) were Enterococcus spp. and 26 (21%) were Escherichia coli. Of 83 Gram-positive isolates, 57 (69%) were susceptible to penicillin. Over all isolates, 92/126 (73%) were susceptible to gentamicin and 117/126 (93%) to enrofloxacin; 62/82 (76%) of Gram-positive, and 22/42 (52%) of Gram-negative bacteria were susceptible to ceftiofur; 53/81 (65%) of Gram-positive, and 23/44 (52%) of Gram-negative bacteria were susceptible to tetracycline; 59/82 (72%) of Gram-positive, and 23/44 (43%) of Gram-negative bacteria were susceptible to trimethoprim-sulfonamide. Of 126 isolates, 33 (26%) had MDR; >1 isolate with MDR was cultured from 24/64 (38%) foals, and ≥2 isolates with MDR were recovered from 8/64 (13%) foals. CONCLUSIONS: Multi-drug resistance, including resistance to commonly used antimicrobials, was found in bacterial isolates from foals in New Zealand. CLINICAL RELEVANCE: The results of this study are of concern from a treatment perspective as they indicate a potential for antimicrobial treatment failure. For future surveillance of AMR and the creation of national guidelines, it is important to record more data on samples submitted for bacterial culture.

Clinical Research Abstracts of the British Equine Veterinary Association Congress 2015.

REASONS FOR PERFORMING STUDY: Decreased efficacy of veterinary antimicrobials and increased prevalence of multi-drug resistance (MDR) is of concern, but little is known of antimicrobial resistance encompassing the New Zealand (NZ) equine population. Recent concerns have arisen over the emergence of multi-resistant bacteria [1], especially on NZ stud farms where antibiotics are frequently used for respiratory disease without veterinary input [2]. OBJECTIVES: To describe bacterial culture and antimicrobial sensitivity results from respiratory samples submitted of young horses (4 weeks to 3 years old). STUDY DESIGN: Retrospective study of clinical pathology records. METHODS: A database search for isolates and sensitivity of respiratory samples from young horses (April 2004-July 2014) was conducted. The results of in vitro sensitivity testing by Kirby-Bauer disk diffusion were tabulated for major bacterial species isolated. Multiple correspondence analysis was used to describe clustering of multi-drug resistance (MDR) and selected demographic variables. RESULTS: 237/289 eligible respiratory samples had at least one aerobic bacterial isolate. Most of the 774 bacterial isolates were Gram-positive (68%). Streptococcus species were the most common genus isolated (40% of isolates). Sensitivity of Streptococcus spp. to penicillin, gentamicin and ceftiofur was >85%, but only 53% to trimethoprim-sulfamethoxone. Gram-negative sensitivity to ceftiofur, tetracycline, and trimethoprim-sulfamethoxone was <75%. MDR was found for 16% of isolates and in 39% of horses. CONCLUSIONS: Penicillin is an appropriate first-line antimicrobial for use in most NZ young horses with suspected bacterial respiratory infection. However, based on findings of MDR, submission of samples for culture and monitoring of sensitivity should be used to inform antimicrobial selection. Ethical animal research: Not applicable. Sources of funding: Massey University McGeorge Fund; New Zealand Equine Research Foundation. Competing interests: None declared.

Antimicrobial Susceptibilities of Aerobic Isolates from Respiratory Samples of Young New Zealand Horses.

BACKGROUND: Decreased efficacy of antimicrobials and increased prevalence of multidrug resistance (MDR) is of concern worldwide. OBJECTIVES: To describe and analyze bacterial culture and antimicrobial susceptibilities from respiratory samples submitted from young horses (4 weeks to 3 years old). ANIMALS: Samples from 289 horses were submitted to a commercial laboratory. METHODS: A retrospective database search of submissions made to a New Zealand veterinary laboratory between April 2004 and July 2014. The results of in vitro susceptibility testing by Kirby-Bauer disc diffusion were described and tabulated for the major bacterial species isolated. Multiple correspondence analysis (MCA) was used to describe the clustering of MDR isolates and selected demographic variables. RESULTS: Overall, 774 bacterial isolates were cultured from 237 horses, the majority of these isolates were gram-positive (67.6%; 95% CI 64.3-70.9%). Streptococcus spp. were the most common genus of bacteria isolated and were 40.1% (95% CI 36.6-43.5%) of the isolates cultured. Susceptibility of Streptococcus spp. to penicillin, gentamicin, and ceftiofur was >85%. Overall, gram-negative susceptibility to ceftiofur, tetracycline, and TMPS was <75%. MDR was defined as resistance to 3 or more antimicrobials, and was found in 39.2% of horses (93/237; 95% CI 33.0-45.5%). CONCLUSIONS AND CLINICAL IMPORTANCE: Culture and susceptibility results have highlighted that MDR is an emerging problem for young horses in New Zealand (NZ), where a bacterial respiratory infection is suspected. This should be considered when prescribing antimicrobials, and emphasizes the need for submission of samples for culture and susceptibility.

Virological and serological investigation of Equid herpesvirus 1 infection in New Zealand.

Infection with equid herpesvirus 1 (EHV-1) may be asymptomatic, or may result in respiratory disease, abortion, neonatal death, or neurological disease. The aim of this study was to estimate the prevalence of EHV-1 infection, including differentiation between genotypes with aspartic acid (D) and asparagine (N) at position 752 of the DNA polymerase sequence, within a selected population of New Zealand horses. The second aim was to determine the predictive value of serology for detection of latently infected horses. Retropharyngeal lymph nodes (RLN) and trigeminal ganglia (TG) were dissected from 52 horses at slaughter and tested for the presence of EHV-1 DNA using magnetic bead, sequence-capture enrichment followed by nested PCR. Sera were tested for EHV-1 antibody using type-specific glycoprotein G ELISA. Overall, 17/52 horses tested positive for EHV-1 DNA. All but one positive PCR results were obtained from RLN samples. Fifteen of the EHV-1 positive horses harboured EHV-1 with N752 genotype, one of which was additionally infected with the D752 genotypes of the virus. Our data comprise the first detection of EHV-1 with D752 genotype in New Zealand and suggest that the "neurovirulent" variant of EHV-1 had been present in New Zealand for at least two years before the first reported outbreak of EHM. All sampled horses tested positive for EHV-4 antibody, and 11/52 tested positive for EHV-1 antibody. The strength of agreement between results of EHV-1 PCR and EHV-1 serology was "fair" (Kappa 0.259, 95% CI: -0.022-0.539), which was likely a reflection of low levels of both EHV-1 antibody in sera and EHV-1 DNA in tissues tested.

Toxocara canis infection and hyperactivity.

An observational study using video recordings and computer assisted data analysis showed that infection with Toxocara canis larvae had a marked effect on five readily and reliably differentiable categories of murine behaviour. The infection was also associated with an increase in the number of shorter bouts of each behavior. These results indicate that infection with T. canis renders mice hyperactive, and would appear to justify a complete reappraisal of the role of this neurotropic parasite as a cause of behavioural abnormalities such as hyperactivity in children.

Experimental toxocariasis and hyperactivity in mice.

An observational study using videorecordings and computer-assisted data analysis was undertaken in order to investigate the behaviour of mice infected with larvae of Toxocara canis. The findings indicated that the infection had a marked effect on five readily and reliably differentiable categories of murine behaviour. A marked increase in the number of shorter bouts of each of the five behaviours was also associated with the infection. These results support previous findings and further suggest that T. canis infection affects the way in which mice respond to their environment. In particular the infection appears to be associated with hyperactivity in mice. Possible causes of such behavioural abnormalities as well as implications of these findings for clinical studies concerned with relationships between T. canis infection and hyperactivity in children are discussed.