Comparison of two sampling and culture systems for detection of Salmonella enterica in the environment of a large animal hospital.

REASONS FOR PERFORMING STUDY: Nosocomial salmonellosis is an important problem in veterinary hospitals that treat horses and other large animals. Detection and mitigation of outbreaks and prevention of healthcare-associated infections often require detection of Salmonella enterica in the hospital environment. OBJECTIVES: To compare 2 previously published methods for detecting environmental contamination with S. enterica in a large animal veterinary teaching hospital. STUDY DESIGN: Hospital-based comparison of environmental sampling techniques. METHODS: A total of 100 pairs of environmental samples were collected from stalls used to house large animal cases (horses, cows or New World camelids) that were confirmed to be shedding S. enterica by faecal culture. Stalls were cleaned and disinfected prior to sampling, and the same areas within each stall were sampled for the paired samples. One method of detection used sterile, premoistened sponges that were cultured using thioglycolate enrichment before plating on XLT-4 agar. The other method used electrostatic wipes that were cultured using buffered peptone water, tetrathionate and Rappaport-Vassiliadis R10 broths before plating on XLT-4 agar. RESULTS: Salmonella enterica was recovered from 14% of samples processed using the electrostatic wipe sampling and culture procedure, whereas S. enterica was recovered from only 4% of samples processed using the sponge sampling and culture procedure. There was test agreement for 85 pairs of culture-negative samples and 3 pairs of culture-positive samples. However, the remaining 12 pairs of samples with discordant results created significant disagreement between the 2 detection methods (P<0.01). CONCLUSIONS: Persistence of Salmonella in the environment of veterinary hospitals can occur even with rigorous cleaning and disinfection. Use of sensitive methods for detection of environmental contamination is critical when detecting and mitigating this problem in veterinary hospitals. These results suggest that the electrostatic wipe sampling and culture method was more sensitive than the sponge sampling and culture method.

Syndromic surveillance for evaluating the occurrence of healthcare-associated infections in equine hospitals.

REASONS FOR PERFORMING STUDY: Methods that can be used to estimate rates of healthcare-associated infections and other nosocomial events have not been well established for use in equine hospitals. Traditional laboratory-based surveillance is expensive and cannot be applied in all of these settings. OBJECTIVES: To evaluate the use of a syndromic surveillance system for estimating rates of occurrence of healthcare-associated infections among hospitalised equine cases. STUDY DESIGN: Multicentre, prospective longitudinal study. METHODS: This study included weaned equids (n = 297) that were admitted for gastrointestinal disorders at one of 5 participating veterinary referral hospitals during a 12-week period in 2006. A survey form was completed by the primary clinician to summarise basic case information, procedures and treatments the horse received, and whether one or more of 7 predefined nosocomial syndromes were recognised at any point during hospitalisation. Adjusted rates of nosocomial events were estimated using Poisson regression. Risk factors associated with the risk of developing a nosocomial event were analysed using multivariable logistic regression. RESULTS: Among the study population, 95 nosocomial events were reported to have occurred in 65 horses. Controlling for differences among hospitals, 19.7% (95% confidence interval, 14.5-26.7) of the study population was reported to have had at least one nosocomial event recognised during hospitalisation. The most commonly reported nosocomial syndromes that were unrelated to the reason for hospitalisation were surgical site inflammation and i.v. catheter site inflammation. CONCLUSIONS: Syndromic surveillance systems can be standardised successfully for use across multiple hospitals without interfering with established organisational structures, in order to provide useful estimates of rates related to healthcare-associated infections.

Using syndromic surveillance to estimate baseline rates for healthcare-associated infections in critical care units of small animal referral hospitals.

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.