Resistome-based surveillance identifies ESKAPE pathogens as the predominant gram-negative organisms circulating in veterinary hospitals.

Introduction: Healthcare-associated infections (HCAIs) associated with extended-spectrum cephalosporin-resistant gram-negative (ESC-R GN) bacteria are an emerging concern in veterinary hospitals, especially in companion animal intensive care units (ICUs). Methods: To understand the molecular epidemiology of ESC-R GN isolates in two veterinary hospitals (equine and small animal), a 6-month pilot study was performed during which fecal and environmental samples were obtained twice from selected patients, upon ICU admission and after 48 h of hospitalization. In total, 295 ESC-R GNs were analyzed using the Acuitas Resistome® Test (OpGen, Maryland, US), a PCR-based assay screening for 50 antimicrobial resistance gene families encoding for production of extended-spectrum beta-lactamase (ESBLs), TEM/SHV/OXA or AmpC beta-lactamases and carbapenemases. Combining organism identification and antimicrobial susceptibility data to genotyping results, unique "Acuitas profiles" were generated that can be used for fast typing the isolates and tracking transmission events. Results: ESKAPE GN pathogens were the most prevalent ESC-R GN isolates circulating in both the small animal and equine hospitals, consisting of Enterobacter cloacae complex (21.7%), Pseudomonas aeruginosa (20%), Klebsiella pneumoniae (15.9%), and Acinetobacter baumannii complex (13.6%) followed by Escherichia coli (12.2%), most harboring a combination of genes encoding for beta-lactamases and ESBLs. Some ESKAPE genotypes showed likely intra-hospital transmission, including E. cloacae (two genotypes, one carrying SHV4, SHV5, and TEM7 and the other TEM1, TEM3, and TEM7 enzymes) in the equine and K. pneumoniae (SHV1, SHV5, and DHA1-positive) in the small animal ICUs, respectively. Furthermore, P. aeruginosa (carrying OXA-50), A. baumannii complex (OXA-51), and E. coli (CTX-M-1) genotypes were isolated across both hospitals, suggesting possible transfer mediated via movement of staff and students. Importantly, isolates carrying transmissible resistance to last-resort antimicrobials (i.e. carbapenems) were identified within the hospital environments, consisting of three environmental Acinetobacter spp. harboring blaOXA - 23 and one clinical E. coli with blaOXA - 48. Conclusion: We describe the widespread occurrence of ESKAPE gram-negative organisms in veterinary ICU patients and hospital environments. Findings from this project provide baseline data on the epidemiology of ESKAPE pathogens in veterinary settings, which can inform infection control policies to aid in patient management and prevent transmission of nosocomial infections associated with these pathogens.

Antimicrobial resistance in clinical bacterial isolates from horses in the UK.

BACKGROUND: Surveillance of antimicrobial resistance (AMR) in horses is important to aid empirical treatment decisions and highlight emerging AMR threats. OBJECTIVE: To describe the AMR patterns of common groups of bacteria from clinical submissions from horses in the UK during 2018, and to determine how this varies by sample site and type of submitting veterinary practice. STUDY DESIGN: Prospective observational study. METHODS: All data on bacterial culture and subsequent antimicrobial susceptibility testing (AST) collected in 2018 from six large equine diagnostic laboratories were included. Resistance patterns were analysed including resistance to 1 or 2 antimicrobial classes, multidrug resistance (MDR), extensively drug resistant (XDR), resistance to highest priority critically important antimicrobials and isolates where there was no readily available treatment for adult horses in the UK. Submitting practices were classified according to whether they treated referral cases or not (first opinion). Comparisons between proportions and resistance for each bacterial group and sample site was performed using Chi-squared (or Fisher's exact test). RESULTS: A total of 6,018 bacterial isolates from 4,038 diagnostic submissions were included from respiratory (n = 1555), urogenital (n = 1,010), skin/hair/wound/abscess (n = 753), surgical site infection (SSI) /catheter-related-infection (CRI) /orthopaedic infections (n = 347) and unknown/'other' submissions (n = 373). There were 2,711 Gram-negative isolates and 3,307 Gram-positive isolates. Prevalence of MDR for E. coli was 31.7%, Staphylococcus spp. 25.3% and > 25% for the majority of bacterial isolates from SSI/CRI/orthopaedic submissions. For Enterococcus spp. there was no readily available treatment for adult horses in the UK in 30.2% of positive submissions. MDR was significantly higher from referral hospital than first opinion submissions for the majority of pathogens (except Actinobacillus spp. and Pasteurella spp. and ß-haemolytic Streptococcus spp.). MAIN LIMITATIONS: Since culture and susceptibility results are not systematic analyses based on harmonised methods, selection bias could impact the findings. CONCLUSIONS: Ongoing surveillance is essential to understand emerging patterns of resistance. MDR is high in SSI/CRI/orthopaedic infections, which is important for hospital biosecurity and guiding treatment decisions. Harmonisation of diagnostic procedures and interpretation of results amongst veterinary laboratories will improve AMR surveillance and data comparison among laboratories.

Bacterial translocation in horses with colic and the potential association with surgical site infection: a pilot study.

BACKGROUND: Surgical site infection (SSI) is a leading cause of morbidity in horses undergoing emergency exploratory laparotomy for the treatment of acute colic. The exact mechanism by which SSI develops in these cases is unclear. This prospective observational study investigated whether bacterial translocation occurs in horses with acute colic and if there is an association between bacterial translocation and development of SSI. METHODS: Peripheral venous blood (PVB) and peritoneal fluid (PF) samples were collected on admission and PF samples were collected at the end of surgery from horses presenting for investigation of acute colic. Any discharge from the laparotomy incision in horses that developed SSI was also collected. All samples were submitted for bacterial culture. RESULTS: In total, 7.7 per cent of PVB samples (3/39), 11.8 per cent (4/34) of admission PF samples and 8.7 per cent (2/23) of the PF samples at surgery were culture positive. The prevalence of SSI was 10.2 per cent. No association was identified between a positive PVB or PF culture and development of a SSI or survival to hospital discharge. CONCLUSION: Bacterial translocation can occur in some horses with acute colic. However, we were unable to identify any association between bacterial translocation and the development of SSIs following emergency exploratory laparotomy.

Heritability of Recurrent Exertional Rhabdomyolysis in Standardbred and Thoroughbred Racehorses Derived From SNP Genotyping Data.

Recurrent exertional rhabdomyolysis (RER) in Thoroughbred and Standardbred racehorses is characterized by episodes of muscle rigidity and cell damage that often recur upon strenuous exercise. The objective was to evaluate the importance of genetic factors in RER by obtaining an unbiased estimate of heritability in cohorts of unrelated Thoroughbred and Standardbred racehorses. Four hundred ninety-one Thoroughbred and 196 Standardbred racehorses were genotyped with the 54K or 74K SNP genotyping arrays. Heritability was calculated from genome-wide SNP data with a mixed linear and Bayesian model, utilizing the standard genetic relationship matrix (GRM). Both the mixed linear and Bayesian models estimated heritability of RER in Thoroughbreds to be approximately 0.34 and in Standardbred racehorses to be approximately 0.45 after adjusting for disease prevalence and sex. To account for potential differences in the genetic architecture of the underlying causal variants, heritability estimates were adjusted based on linkage disequilibrium weighted kinship matrix, minor allele frequency and variant effect size, yielding heritability estimates that ranged between 0.41-0.46 (Thoroughbreds) and 0.39-0.49 (Standardbreds). In conclusion, between 34-46% and 39-49% of the variance in RER susceptibility in Thoroughbred and Standardbred racehorses, respectively, can be explained by the SNPs present on these 2 genotyping arrays, indicating that RER is moderately heritable. These data provide further rationale for the investigation of genetic mutations associated with RER susceptibility.

Epidemiology of exertional rhabdomyolysis susceptibility in standardbred horses reveals associated risk factors and underlying enhanced performance.

BACKGROUND: Exertional rhabdomyolysis syndrome is recognised in many athletic horse breeds and in recent years specific forms of the syndrome have been identified. However, although Standardbred horses are used worldwide for racing, there is a paucity of information about the epidemiological and performance-related aspects of the syndrome in this breed. The objectives of this study therefore were to determine the incidence, risk factors and performance effects of exertional rhabdomyolysis syndrome in Standardbred trotters and to compare the epidemiology and genetics of the syndrome with that in other breeds. METHODOLOGY/PRINCIPAL FINDINGS: A questionnaire-based case-control study (with analysis of online race records) was conducted following identification of horses that were determined susceptible to exertional rhabdomyolysis (based on serum biochemistry) from a total of 683 horses in 22 yards. Thirty six exertional rhabdomyolysis-susceptible horses were subsequently genotyped for the skeletal muscle glycogen synthase (GYS1) mutation responsible for type 1 polysaccharide storage myopathy. A total of 44 susceptible horses was reported, resulting in an annual incidence of 6.4 (95% CI 4.6-8.2%) per 100 horses. Female horses were at significantly greater risk than males (odds ratio 7.1; 95% CI 2.1-23.4; p = 0.001) and nervous horses were at a greater risk than horses with calm or average temperaments (odds ratio 7.9; 95% CI 2.3-27.0; p = 0.001). Rhabdomyolysis-susceptible cases performed better from standstill starts (p = 0.04) than controls and had a higher percentage of wins (p = 0.006). All exertional rhabdomyolysis-susceptible horses tested were negative for the R309H GYS1 mutation. CONCLUSIONS/SIGNIFICANCE: Exertional rhabdomyolysis syndrome in Standardbred horses has a similar incidence and risk factors to the syndrome in Thoroughbred horses. If the disorder has a genetic basis in Standardbreds, improved performance in susceptible animals may be responsible for maintenance of the disorder in the population.