Helen Aceto

Outbreak of Salmonellosis Caused by Salmonella enterica Serovar Newport MDR‐AmpC in a Large Animal Veterinary Teaching Hospital

BACKGROUND Nosocomial salmonellosis is an important problem for large animal veterinary teaching hospitals (VTHs). OBJECTIVE To describe failure of an Infection Control Program (ICP) that resulted in an outbreak of salmonellosis caused by Salmonella Newport multidrug resistant (MDR)-AmpC at a large animal VTH. ANIMALS Sixty-one animals identified with the outbreak strain of Salmonella. METHODS Retrospective study: Data collected included signalment, presenting complaint, duration of hospitalization, discharge status, and financial information. Phenotypic and genotypic characterization was performed on Salmonella isolates. RESULTS The outbreak occurred despite an existing ICP; the ICP was reviewed and weaknesses identified. Routine patient surveillance was not performed before or during the outbreak; fecal sampling was triggered only by a patient algorithm based on clinical signs. Sixty-one animals were infected with the outbreak strain of S. Newport, and the majority were horses (n = 54). Case fatality rate was 36.1%. S. Newport isolates demonstrated high genetic similarity (Dice ≥ 0.96), and all had the MDR-AmpC phenotype. Environmental persistence of the organism necessitated complete hospital closure, extensive decontamination, and remediation of the facility. A paradigm shift in the relevance of biosecurity in a VTH and the establishment of a stringent ICP were integral components of successful hospital reopening. CONCLUSIONS AND CLINICAL IMPORTANCE An ineffective ICP resulted in a nosocomial outbreak caused by a MDR S. Newport in a VTH. Closure of a VTH affected all missions of the institution and had substantial financial impact (US

Retrospective multicentre study of methicillin-resistant Staphylococcus aureus infections in 115 horses.

4.12 million).

Post operative infection, pyrexia and perioperative antimicrobial drug use in surgical colic patients

REASONS FOR PERFORMING STUDY Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging veterinary and zoonotic pathogen, associated with increasing reports of disease in horses. OBJECTIVES To provide an overview of the characteristics of clinical MRSA infections in horses. METHODS A retrospective case study was performed on 115 horses admitted to 6 participating veterinary teaching hospitals in Canada and the United States between 2000 and 2006, and diagnosed with clinical MRSA infection. Descriptive statistics, univariate and multivariable analyses for community- (CA) vs. hospital-associated (HA) MRSA infections, and survival vs. nonsurvival at discharge were performed. RESULTS The age range of MRSA-infected horses was zero (born in hospital) to 31 years. HA (58/114, 50.9%) and CA infections (56/114, 49.1%) were equally common. Infection of surgical incisions was most frequently reported (44/115, 38.0%). Overall 93/111 (83.8%) cases survived to discharge. Previous hospitalisation and treatment with gentamicin were associated significantly with CA-MRSA, whereas infected incision sites were associated significantly with HA-MRSA. Factors significantly associated with nonsurvival included i.v. catheterisation, CA-MRSA infection and dissemination of infection to other body sites. CONCLUSIONS Equine MRSA infections have a broad range of clinical presentations, appear to be primarily opportunistic and the overall prognosis for survival to discharge is good. POTENTIAL RELEVANCE These results should help direct future research with regard to investigation of risk factors for equine MRSA infection in community and hospital populations.

Report of the third Havemeyer workshop on infection control in equine populations

REASONS FOR PERFORMING STUDY Infections are common complications in post operative colic patients. It is the impression of some surgeons that pyrexia in the early post operative period is a sign of infection and appropriate timing of perioperative antimicrobials will decrease the incidence of post operative infection. OBJECTIVE To determine the association between 1) post operative pyrexia and development of infection and 2) perioperative antimicrobial drug use and infection rate in post operative colic patients. METHODS Medical records of patients undergoing surgical treatment for colic were reviewed. Horses recovering from surgery and surviving >48 h were included. Data relating to case details, duration of surgery, post operative infection, peri- and post operative antimicrobial administration, presence, intensity and duration of pyrexia, were recorded. Data were analysed using standard statistical methods for simple comparisons between groups and by logistic regression for more complex comparisons. RESULTS One-hundred-and-thirteen horses were included in the final analyses, 48 (43%) of which were diagnosed with a post operative infection. Duration of surgery and anaesthesia were associated with post operative infection. Eighty-five percent of horses (n = 96) exhibited pyrexia (rectal temperature >38.3°C) post operatively. Peak temperature >39.2°C, time post surgery to peak temperature >48 h and duration of pyrexia >48 h were significantly associated with infection. In a combined model, time to first pyrexic >48 h post surgery, peak temperature and time to peak >48 h were equally weighted and the models positive predictive value for post operative infection was 72%. Timing and dose rate of preoperative antimicrobials were not associated with infection but duration of post operative antimicrobial drug use was. CONCLUSION AND CLINICAL RELEVANCE Slight to mild pyrexia (38-39.4°C) in the early post operative period is not necessarily associated with impending bacterial infection in colic patients and the use of antimicrobials in these patients may be costly and unnecessary.

Comparison of short- and long-term complications and survival following jejunojejunostomy, jejunoileostomy and jejunocaecostomy in 112 horses: 2005-2010.

Infectious diseases are an ever present threat to the health of individual horses, local, regional and national herds and the equine industry as a whole. Treating infectious disease has always been one of the foundations of veterinary medicine. However, infectious disease prevention is becoming increasingly important because of the high visibility of recent outbreaks of infectious disease, the increasing frequency and ease of national and international horse movement and emergence and re-emergence of equine pathogens. This is especially true in large, transient horse populations. For many veterinarians and facility managers, infection control remains a subject they are reluctant to discuss for fear of it reflecting poorly on them, yet management of infectious diseases is an unavoidable issue that must be addressed by all equine practitioners regarding every equine population under their care. The field of veterinary infection control, although still young compared with equivalent efforts in human medicine, has advanced considerably in the last decade thanks to those that have willingly and openly shared their experiences – both good and bad – with regard to hospital and field-based outbreaks of infectious diseases and subsequent mitigation efforts. In veterinary hospitals, infection control is often not considered until after individual patient care is addressed and thus prevention of infectious disease transmission can become a secondary activity relative to the treatment of individual horses and a tertiary activity relative to the care of the larger hospital population. Thus infection control has often been largely reactive rather than proactive in many equine facilities. Control efforts are sometimes hurriedly implemented after a disease outbreak is well underway, rather than being used to prevent sporadic cases from escalating into an outbreak. It is clear that outbreaks of infectious disease can occur with alarming frequency, even in highly controlled environments such as veterinary teaching hospitals. A survey of personnel responsible for infection control at 38 American Veterinary Medical Association (AVMA) accredited veterinary teaching hospitals found that 82% had identified at least one outbreak of hospital-associated disease in the previous 5 years with 32% reporting outbreaks so significant that hospital closure was utilised to aid in mitigation efforts [1]. Outbreaks are undoubtedly under-reported in the scientific literature but a variety of organisms have been previously documented as causes of epidemic disease in equine hospitals, including Salmonella enterica [2–5], methicillin-resistant Staphylococcus aureus (MRSA) [6–8], equine herpesvirus type 1 [9–11] and Cryptosporidium [12]. However, equine infectious diseases are not solely associated with veterinary hospitals. The last decade has seen the epidemic spread of West Nile virus in North America, a major equine influenza epidemic in Australia, outbreaks of contagious equine metritis in the USA and South Africa, the re-emergence of piroplasmosis in the USA and dramatically increasing concerns regarding equine herpesvirus myeloencephalopathy and multidrug resistant bacterial pathogens (e.g. MRSA). There are several significant differences with regard to the practice of infection control in equine populations outside of veterinary hospitals (i.e. ‘in the field’). The focus in field situations is likely to be the protection of a relatively healthy population of horses from disease incursion, rather than protection of hospitalised patients with varying degrees of compromised health. The differences are similar to those between protection of public health in the community and infection control in human hospitals. Infection control in the field has often focused heavily on vaccination; however, effective vaccines cannot fully protect all horses as vaccines are not available for many diseases and vaccination cannot be used to control emerging diseases. A fundamental shift in the mindset of clinicians and horse owners must occur whereby vaccination is considered a last line of defence and overall infection prevention emphasises implementation of other control measures. This is particularly critical in large, transient horse populations that gather for specific events due to the potential for serious and widespread repercussions when these populations disperse, as was seen following the National Cutting Horse Association Western National Championship in Ogden, Utah, in May 2011. It is likely that exposure to a single horse shedding equine herpesvirus-1 (EHV-1) at this event resulted in over 165 horses developing clinical disease that was known or suspected to be caused by EHV-1 and at least 13 of these horses were subjected to euthanasia. The outbreak spanned at least 10 western US states and 2 Canadian provinces ([13], P.S. Morley, personal communication 2012). Clearly infectious diseases have a tremendous impact on equine populations and efforts to control and prevent spread are critical to the well-being of individual horses and horse populations. The Dorothy Russell Havemeyer Foundation Inc. (http://www.havemeyerfoundation. org) is a private foundation that supports scientific efforts to improve the health and welfare of horses. To this end, the foundation conducts workshops in a variety of different subject areas, including the control of infectious diseases. The most recent Havemeyer workshop conducted on infection control in equine populations was held in September 2010, bringing together a diverse group of internationally recognised experts in fields related to infection control. The overarching goal of the workshop was to advance the discipline by providing guidance and inspiration to those currently involved in equine infection control and insight to those who may still be on its periphery. More specifically, the objective of this workshop was to identify the most urgent and critical priorities in equine infection control so that these might be targeted for research and resource development. In this report, we summarise the consensus opinions, major ideas and recommendations developed during the workshop. In working to summarise the discussion and major conclusions of this workshop, several common themes became apparent that were deemed essential to the future progress of the discipline of infection control. Specifically, these included ethical obligations and standards of practice regarding infection control, improvements and standardisation for surveillance methods, developing better education and training programmes, standardisation and development of new diagnostic tests for important contagious pathogens, objectively quantifying the costs and benefits of infection control programmes, expanding knowledge necessary for design of control programmes for important contagious pathogens, developing and promoting multicentre studies and promoting judicious antimicrobial use practices. Approaches that can be used for development of infection control programmes (the ‘how to’ of infection control) were discussed in previous Havemeyer workshops and have been reviewed in detail elsewhere [14–17]. Issues regarding the detection and control of specific agents were discussed and were used as examples during the meeting but the focus of this document is on the future needs of infection control in a broader context, not in relation to specific diseases.

Antimicrobial Use in Horses Undergoing Colic Surgery

REASONS FOR PERFORMING THE STUDY There is disagreement among surgeons over whether jejunoileostomy (JI) or jejunocaecostomy (JC) is the better method of anastomosis following proximal ileal resection. OBJECTIVE To compare short- and long-term complications and outcome in horses undergoing jejunojejunostomy (JJ), JI and JC and to test the hypotheses that a higher proportion of horses undergoing JI would have short-term complications and mortality compared with horses undergoing JC or JJ and that JC would be associated with a higher long-term mortality and occurrence of colic. STUDY DESIGN Retrospective cross-sectional study. METHODS Medical records of horses undergoing celiotomy for a small intestinal obstruction and JJ, JI or JC from 2005 to 2010 were reviewed. Post operative complications were recorded. Short-term outcome was alive vs. dead at hospital discharge and was analysed using a Chi-squared test. Long-term follow-up was obtained and a Kaplan-Meier estimate of the survivor function was performed. RESULTS There were 112 horses included. A higher proportion of JI horses had a repeat celiotomy during hospitalisation compared with horses undergoing JC. The number of horses alive at hospital discharge was not different between groups: JJ 79% (95% confidence interval [CI] 68-90%), JI 78% (95% CI 61-96%), JC 83% (95% CI 71-96%). Among horses discharged with long-term follow-up, more horses had colic after JC compared with JJ or JI. Long-term post discharge survival based on the Kaplan-Meier survivor function was lower for horses undergoing JC than JJ or JI (P = 0.04). CONCLUSION While there was no difference in short-term outcome between groups, more horses with JI underwent a repeat celiotomy during hospitalisation. Horses with a JC were more likely to have long-term complications with colic. Horses that were subjected to euthanasia because of colic within 12 months of hospital discharge either had a JC or repeat celiotomy. The results suggest that, when possible, a JI may be the preferred method of anastomosis based on more favourable survival and lower occurrence of colic long term.

A Multicenter Retrospective Study of 151 Renal Biopsies in Horses

BACKGROUND Recommendations for antimicrobial prophylaxis for surgery are well-described in human medicine, but information is limited for veterinary practice. OBJECTIVE To characterize antimicrobial use in horses undergoing emergency colic surgery. ANIMALS A total of 761 horses undergoing emergency colic surgery (2001-2007). METHODS Retrospective case review. Antimicrobial dose and timing, surgical description, and duration of treatment were collected from medical records. Associations between antimicrobial use and the occurrence of fever, incisional inflammation or infection, catheter-associated complications, or Salmonella shedding during hospitalization were analyzed using rank-sum methods and logistic regression. RESULTS A total of 511 (67.2%) horses received an inappropriate amount of drug preoperatively. Median time from preoperative dose to incision was 70 (IQR 55-90) minutes; median total surgery time was 110 (IQR 80-160) minutes. Seventy-three horses were euthanized under anesthesia because of poor prognosis. Of 688 horses, 438 should have been redosed intraoperatively based on the duration of surgery. Only 8 (1.8%) horses were redosed correctly. Horses remained on perioperative antimicrobials a median of 3 (IQR 2-4.5) days. Antimicrobial therapy was reinstituted in 193 (28.9%) horses, and median days of total treatment were 3.8 (IQR 2-6). Signs that led to reinstituting therapy were fever (OR 3.13, P = .001) and incisional inflammation/infection (OR 2.95, P = .001). Horses in which treatment was reinstituted had 2.3 greater odds of shedding Salmonella (P = .003). Increased surgical time was associated with longer duration of antimicrobial therapy (OR 1.02, P = .001). CONCLUSIONS AND CLINICAL RELEVANCE Despite published recommendations regarding antimicrobial prophylaxis, compliance is poor; improvement might reduce postoperative complications.

Using Syndromic Surveillance to Estimate Baseline Rates for Healthcare-Associated Infections in Critical Care Units of Small Animal Referral Hospitals

BACKGROUND Renal biopsies are uncommonly performed in horses and little is known about their diagnostic utility and associated complication rate. OBJECTIVE To describe the techniques, the complication rate, risk factors, and histopathology results; as well as evaluate the safety and diagnostic utility of renal biopsy in the horse. ANIMALS One hundred and forty-six horses from which 151 renal biopsies were obtained. Animals ranged in age from 48 hours to 30 years. METHODS Multicenter retrospective study, with participation of 14 institutions (1983-2009). RESULTS Renal biopsy in horses was associated with a similar rate of complications (11.3%) to that occurring in humans and companion animals. Complications were generally associated with hemorrhage or signs of colic, and required treatment in 3% of cases. Fatality rate was low (1/151; 0.7%). Biopsy specimens yielded sufficient tissue for a histopathologic diagnosis in most cases (94%) but diagnoses had only fair (72%) agreement with postmortem findings. Risk factors for complications included biopsy specimens of the left kidney (P = .030), a diagnosis of neoplasia (P = .004), and low urine specific gravity (P = .030). No association with complications was found for age, sex, breed, institution, presenting complaint, other initial clinicopathologic data, biopsy instrument, needle size, or use of ultrasonographic guidance. CONCLUSIONS AND CLINICAL IMPORTANCE Renal biopsy in horses has low morbidity and results in a morphological histopathologic diagnosis in 94% of cases. However, this procedure might result in serious complications and should only be used when information obtained would be likely to impact decisions regarding patient management and prognosis.

Using Quarterly Earnings to Assess Racing Performance in 70 Thoroughbreds after Modified Laryngoplasty for Treatment of Recurrent Laryngeal Neuropathy

BACKGROUND Expected rates of healthcare-associated infections (HCAI) have not been established in veterinary hospitals. Baseline rates are critically needed as benchmarks for quality animal care. OBJECTIVE To estimate the occurrence of events related to HCAI identified using a standardized syndromic surveillance system in small animals in critical care cases at referral hospitals. ANIMALS Weaned dogs and cats (n = 1,951) that were hospitalized in the critical care unit of referral teaching hospitals during a 12-week period. METHODS Multicenter, prospective longitudinal study. A survey was completed for all enrolled animals to record basic demographics, information about procedures and treatments that animals received, and to document the occurrence of defined nosocomial syndromes. Data were analyzed to identify risk factors associated with the occurrence of these nosocomial syndromes. RESULTS Controlling for hospital of admission, 16.3% of dogs (95% confidence intervals [CI], 14.3-18.5) and 12% of cats (95% CI, 9.3-15.5) were reported to have had ≥ 1 nosocomial syndrome occur during hospitalization. Risk factors found to have a positive association with the development of a nosocomial syndrome were longer hospital stays, placement of a urinary catheter, surgical procedures being performed, and the administration of antiulcer medications and antimicrobial drugs excluding those given perioperatively. CONCLUSIONS AND CLINICAL IMPORTANCE Syndromic surveillance systems can be successfully standardized for use across multiple hospitals to effectively collect data pertinent to HCAI rates and risk factors for occurrence.

Retrospective Evaluation of Horses Diagnosed with Neuroborreliosis on Postmortem Examination: 16 Cases (2004-2015).

OBJECTIVE To validate and then use quarterly earnings to assess racing performance of Thoroughbreds after modified laryngoplasty for treatment of recurrent laryngeal neuropathy STUDY DESIGN Retrospective cohort study. ANIMALS Thoroughbred racehorses after modified laryngoplasty (N = 70), and untreated cohorts (N = 210). METHODS Medical (2005-2008) and race records of 70 Thoroughbred racehorses treated by modified laryngoplasty were reviewed. Postsurgery data were collated as the number of starts and the dollar race winnings for each quarter after the date of surgery. Comparisons were made to an untreated cohort population. Initial comparisons were made between subgroups of the untreated cohort to ensure that one randomly selected group of untreated horses would not differ significantly from another untreated group. RESULTS In the last race before surgery, treated horses performed significantly (P < .001) worse than untreated horses. When data were examined by quarter, with the exception of the first quarter after surgery, there were no significant differences in race starts or dollars earned between treated horses and untreated cohorts. All treated horses had at least 1 race after surgery and there was no difference in cumulative survival up to 40 races after surgery between treated and untreated groups CONCLUSIONS Quarterly earnings can be used to provide a more detailed longitudinal assessment of a racehorses performance. Horses treated by modified laryngoplasty for recurrent laryngeal neuropathy return to similar level of performance as their untreated cohorts by the second quarter after surgery, and continue to compete as long as their cohorts.