Commercial Veterinary Laboratory Research Articles

Antimicrobial susceptibility patterns of aerobic bacteria isolated from canine urinary samples in South East Queensland, 2013 to 2018.

Urinary tract infections are a common diagnosis in dogs presenting to veterinary practice. Veterinarians often treat suspected infections empirically, either in the absence of culture and susceptibility testing results or whilst waiting for them. This study aimed to identify the bacteria most frequently isolated from canine urinary samples and their antimicrobial susceptibility patterns in South East Queensland (SEQ) to help guide responsible empirical antimicrobial prescription by the veterinary community in this geographical location. Cumulative antibiograms were generated from the results of 1284 culture-positive urinary samples in SEQ, obtained from a commercial veterinary laboratory over a 5-year period. Escherichia coli was the most commonly isolated bacterial species (43%), followed by Staphylococcus spp. (23%), Proteus spp. (21%) and Enterococcus spp. (10%). Of the six most common isolates, 97% had susceptibility to at least one low-importance antimicrobial. Susceptibility to the low-importance and first-line antimicrobial recommendation, amoxicillin, was 81% for E. coli and 24% for Staphylococcus spp. Susceptibility of both E. coli and Staphylococcus spp. to medium-importance and commonly recommended empirical antimicrobials, trimethoprim sulphonamides and amoxicillin-clavulanic acid was ≥85% and >92% for high-importance antimicrobials enrofloxacin and ceftiofur. Of the E. coli and Staphylococcus spp. isolates, 8.8% and 4%, respectively, were considered multidrug resistant. There was no increase in resistance to antimicrobials detected over the study period. Susceptibilities suggest low- and medium-importance antimicrobials remain acceptable first-line empirical treatments. However, this should be continually assessed and updated using local surveillance data.

Establishment of a Real-Time PCR Assay for the Detection of Devriesea agamarum in Lizards

(1) Background: Devriesea (D.) agamarum is a potential cause of dermatitis and cheilitis in lizards. The aim of this study was to establish a real-time PCR assay for the detection of D. agamarum. (2) Methods: Primers and probe were selected targeting the 16S rRNA gene, using sequences of 16S rRNA genes of D. agamarum as well as of other bacterial species derived from GenBank. The PCR assay was tested with 14 positive controls of different D. agamarum cultures as well as with 34 negative controls of various non-D. agamarum bacterial cultures. Additionally, samples of 38 lizards, mostly Uromastyx spp. and Pogona spp., submitted to a commercial veterinary laboratory were tested for the presence of D. agamarum using the established protocol. (3) Results: Concentrations of as low as 2 × 104 colonies per mL were detectable using dilutions of bacterial cell culture (corresponding to approximately 200 CFU per PCR). The assay resulted in an intraassay percent of coefficient of variation (CV) of 1.31% and an interassay CV of 1.80%. (4) Conclusions: The presented assay is able to detect D. agamarum in clinical samples, decreasing laboratory turn-around time in comparison to conventional culture-based detection methods.

Detection of nidoviruses in samples collected from captive snakes in Europe between 2016 and 2021.

Nidoviruses are increasingly detected in various snake species worldwide, but much remains to be learned about their distribution and the factors influencing their epidemiology. This retrospective study evaluated the results of routine nidovirus testing, by PCR, of 5210 swab samples from pet snakes from various European countries that were submitted to a commercial veterinary laboratory in Germany between 2016 and 2021. The overall detection rate was 19.96%. However, the detection rate varied significantly depending on the snake species (p < 0.0001), with the highest rate in Indian pythons (Python molurus) (42.24%). Rates also varied depending on the season of sample collection (p < 0.0001), with the highest rate in winter (24.46%), and the country of sample origin (p < 0.0001), with the highest rate in Austria (36.69%). The detection rate also decreased significantly (p = 0.0003) over the 6-year observation period, from 26.43% to 17.64%. No information on clinical signs was available for most of the sampled snakes. The present study supplies new information on the distribution of python nidoviruses (subgenus Roypretovirus) in pet snakes in Europe and indicates a dynamic situation with possible changes in prevalence over time.

Neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and C-reactive protein concentration in female domestic cats subjected to ovariohysterectomy

This study assessed hematological parameters (especially the neutrophil-to-lymphocyte ratio and the platelet-to-lymphocyte ratio) and the C-reactive protein concentration in the plasma of female cats subjected to ovariohysterectomy: prior to surgery as well as 2 and 10 days after surgery. The animals (n = 26) were patients of a private veterinary clinic between July 2019 and March 2021 and were brought there for ovariohysterectomies. The blood was sampled from the cephalic vein into two tubes. One of the tubes was sent to a commercial veterinary laboratory, where a hematological examination was performed. The second tube was centrifuged (2000 g, 10 min). After separation, plasma samples were stored at –80°C. Next, the CRP concentration was determined using an ELISA kit. We noted a statistically significant increase in NLR two days after surgery. The difference in the NLR value before the surgery and after a 10-day recovery period failed to reach statistical significance. Changes in PLR and the CRP concentration during the experiment were insignificant. The results indicate that NLR is an effective marker of stress and inflammation caused by surgery in female cats, whereas the CRP concentration is of no use in this species.

Evaluation of Sysmex XT-2000iV analyzer performance across a network of five veterinary laboratories using a commercially available quality control material.

Laboratory and instrument harmonization is seldom reported in the veterinary literature despite its advantages to clinical interpretation, including the use of interchangeable results and common reference intervals within a system of laboratories. A three-step process was employed to evaluate and optimize performance and then assess the appropriateness of common reference intervals across a network of six Sysmex XT-2000iV hematology analyzers at 5 commercial veterinary laboratory sites. The aims were to discover if harmonization was feasible in veterinary hematology and which quality parameters would best identify performance deviations to ensure a harmonized status could be maintained. The performance of 10 measurands of a commercially available quality control material (Level 2-Normal e-CHECK (XE)-Hematology Control) was evaluated during three 1-month time periods. Precision and bias were assessed with Six Sigma, American Society of Veterinary Clinical Pathology (ASVCP) total error quality goals and biologic variation (BV)-based quality goal approaches to performance measurement. Instrument adjustments were made to 1 analyzer twice and 3 analyzers once between evaluations to improve performance and achieve harmonization. Sigma metrics improved from 37/50>6 to 58/60>6 and to all >5 over the course of the harmonization project. BV-based quality goals for desirable bias and for laboratory systems of 0.33×CVI (within-subject biologic variation) were more sensitive and useful for assessing performance than the ASVCP total error goals. Optimization and harmonization were achieved, and because BV-derived bias goals were achieved, common reference intervals could be implemented across the network of analyzers.

Frequency and classification of errors in laboratory medicine at a veterinary teaching hospital in the United States.

The accuracy of laboratory data is of utmost importance. Data regarding laboratory error in human laboratories are often extrapolated into veterinary settings. One study investigated the rate and type of errors in a European commercial veterinary laboratory, but that data might not directly apply to an educational setting. This study determined the frequency and type of errors in laboratory medicine at a veterinary teaching hospital. Errors associated with clinical pathology samples were recorded over two 60-day periods. The first period included a time when new students and house officers started at the veterinary school. The second time period was 6months later. The errors were assigned to categories, and the frequency of each was calculated. Sample hemolysis, icterus, and lipemia were evaluated separately using an automated index, as these conditions could be pathologic or the result of error. Frequencies of error and hemolysis, icterus, and lipemia were assessed between the groups. Total error rates were 4.7% and 3.5% for the first and second periods, respectively. The frequency of each error subclassification was similar to those observed in the veterinary and human literature, with preanalytic error predominating. Statistically significant differences in the overall error rate and percentage of preanalytic errors that occurred outside of and within the laboratory were observed comparing differences between the two periods. The overall error rate in this veterinary teaching hospital was slightly higher than that previously reported in other settings, although a proportion of errors was as expected. Areas needing improvement were identified, and strategies to reduce error could be developed.

Demographic risk factors for lymphoma in Australian dogs: 6201 cases

BackgroundLymphoma is common in the dog. Studies of population risk factors primarily have been derived from referral institution or insurance data.ObjectiveTo identify and quantify the host risk factors for lymphoma in a broad population of Australian dogs.AnimalsData on 6201 client owned dogs were retrieved from a commercial veterinary laboratory, a general practice group and 2 referral hospitals.MethodsData collected included breed, sex, and neuter status. A reference population of 640 105 dogs was generated from the referral hospitals and from council registration data. The risk of lymphoma by sex and neuter status was calculated as odds ratios (OR).ResultsThe study identified 30 breeds at increased risk of lymphoma, 15 that have not been reported previously, and 26 breeds at decreased risk, 18 that have not been reported previously. Males were over represented compared to females with an OR of 1.1 (95% CI, 1.1–1.2; P < .001). Neutered animals were at higher risk compared to intact animals with an OR of 3.2 (95% CI, 2.9–3.5) which was found in both males (OR, 2.8; 95% CI; 2.5–3.2) and females (OR, 4.4; 95% CI, 3.5–5.1).Conclusions and Clinical ImportanceBreed, sex, and neuter status alter the risk of lymphoma in dogs. These 3 factors must be considered when evaluating lymphoma risk as potential markers of underlying differences in disease etiology. Comparison of breeds at increased and decreased risk could be advantageous when evaluating specific etiological factors.

Giving your heart to pathology.

Jim KIaassen recently joined Axiom Veterinary Laboratories as a clinical pathologist. During his career, Dr Klaassen has worked in small animal practice, lectured in clinical pathology, undertaken preclinical research and held senior roles in commercial veterinary laboratories in the USA, including as chief medical officer of Antech Diagnostics.

Antimicrobial resistance in Staphylococcus aureus, Streptococcus uberis and Streptococcus dysgalactiae from dairy cows with mastitis

AIMS: To determine the minimal inhibitory concentrations (MIC) of antimicrobials for common mastitis pathogens from dairy cows in New Zealand; and to assess the effect of source of the isolates, i.e. commercial veterinary laboratories or collected as part of research studies; the clinical status of the cow, i.e. subclinical or clinical mastitis; cow age and herd on the distribution of the MIC.METHODS: Minimal inhibitory concentrations for Staphylococcus aureus (n=364), Streptococcus dysgalactiae (n=65) and Streptococcus uberis (n=102) isolated from milk samples from dairy cows were determined for a variety of antimicrobials using broth microdilution. Isolates of S. aureus were sourced from research studies from both subclinically (n=161) and clinically (n=104) affected cows, as well as from commercial veterinary laboratories (n=101); while all the streptococcal isolates were from commercial laboratories. Resistance was defined using the cut-points provided by the Clinical and Laboratory Standards Institute (CLSI).RESULTS: The distribution of MIC varied among the bacterial species for every antimicrobial tested (p<0.001). Of the S. aureus isolates, 28, 2 and 0.5% were resistant to penicillin, ampicillin and trimethoprim/sulfamethoxazole, respectively. For S. dysgalactiae and S. uberis isolates, 17 and 13% were resistant to trimethoprim/sulfamethoxazole, respectively. One isolate (1%) of S. uberis was resistant to penicillin. The distribution of MIC of S. aureus varied with clinical status, between herds, and with age of cow (p<0.05). The distribution of MIC for S. aureus for penicillin, amoxicillin/clavulanic acid, cloxacillin and ampicillin were lower from clinical than subclinical cases, and those for amoxicillin/clavulanic acid and oxytetracycline from isolates from veterinary laboratories were lower than for those from research studies.CONCLUSIONS: Resistance to some beta-lactam antimicrobials and trimethoprim/sulfamethoxazole were found in isolates from cases of bovine mastitis. The distribution of MIC for isolates of S. aureus varied with clinical status of the cow, the age of the cow, the herd and with the source of isolate.CLINICAL SIGNIFICANCE: Resistance to penicillin was found in a quarter of S. aureus isolates, but in virtually no Streptococcus isolates; therefore microbial identification and sensitivity testing would be beneficial when assessing treatment options. The source of the isolates affected the estimated MIC, suggesting that selection of isolates for monitoring of resistance requires care and that use of routine submissions to commercial laboratories to assess antimicrobial resistance patterns may result in biased estimates of prevalence of resistance.

A descriptive analysis of the antimicrobial susceptibility of mastitis-causing bacteria isolated from samples submitted to commercial diagnostic laboratories in New Zealand (2003–2006)

AIM: To describe the antimicrobial susceptibility of mastitis-causing bacteria isolated from milk samples submitted to commercial laboratories over a period of 40 months. METHODS: The records of reported results of milk samples submitted by veterinary practitioners to five commercial veterinary laboratories in the North and South Islands of New Zealand, between August 2003 and December 2006 were reviewed. Logistic regression was used to analyse the effect of year, island, and the interaction of year and antimicrobial on the probability of antimicrobial susceptibility for each pathogen and antimicrobial combination, where the causative bacteria had >1,000 susceptibility tests in total and the antimicrobials was tested on >500 isolates. A total of 9,262 isolates were included in this study, with an average of nearly seven susceptibility tests per isolate, totalling 62,918 tests. RESULTS: Streptococcus uberis isolates demonstrated high overall susceptibility (>90.0%) to the majority of antimicrobial agents except ampicillin (81.7%), lincomycin (85.3%), trimethoprim/sulphonamide combination (88.6%), and, as expected, aminoglycosides (<4%). The susceptibility of Strep. dysgalactiae was similar to that of Strep. uberis, except for greater susceptibility to oxacillin (98.1%) and much lower susceptibility to tetracyclines (11.2%). The susceptibility of Staphylococcus aureus isolates was markedly different from that of Strep. uberis for the majority of antimicrobials tested. Susceptibility of Staph. aureus was lower than 90% to ampicillin (73.4%), erythromycin (74.7%), lincomycin (66.1%), penicillin (73.1%), and streptomycin (71.7%). No antimicrobial was effective against all Staph. aureus isolates. Minor changes were found in the overall susceptibility of the main mastitis-causing bacteria between 2003 and 2006. CONCLUSIONS: The antimicrobial agents intended for treatment of bovine mastitis currently available in New Zealand generally demonstrated good in-vitro efficacy against streptococci and staphylococci, with the exception of aminoglycosides. CLINICAL RELEVANCE: Analysis of the results of antimicrobial susceptibility of bacterial isolates from milk samples from dairy cows in New Zealand provides useful data for surveillance purposes, and a baseline for identifying changes in antimicrobial sensitivity in this population. However, the variation in antimicrobial susceptibility between individual isolates means that these data are of limited value when determining treatment of mastitis at the farm level.

The perceived and actual diagnostic utility of veterinary cytological samples

To establish the proportion of cytology samples sent to a commercial veterinary laboratory that yields diagnostically useful information in the context of current use and perceptions of cytology. Nine hundred and forty-five cytology submissions were retrospectively collected and categorised according to diagnostic utility. A survey into the use and perceptions of cytology was distributed at the British Small Animal Veterinary Association Congress 2008. A specific diagnosis was reached in 23.1 per cent of samples and a cytological diagnosis in 35.3 per cent. 22.4 per cent of samples yielded some useful information, but 19.2 per cent were unacceptable. Seventy-four participants in the survey took an average of 3.9 cytological samples per week, of which they examined 27.0 per cent in-house only, 21.6 per cent in-house before sending to an external laboratory and 51.4 per cent were sent externally without prior examination. "To obtain a definitive diagnosis" was the principal reason cited for performing cytology. Results suggest that cytology is underused and may be applied in an inappropriate context in the UK. It is hoped that illustrating the diagnostic outcome of samples received by a commercial laboratory will encourage increased, appropriate use of cytology.

Retrospective Study of Canine Insulinomas: Eight Cases (2005-2008)

This retrospective study examined 8 cases of pathologically diagnosed insulinoma. Surgical intervention was performed in all cases, once insulinoma was suspected based on unique clinical signs, hypoglycemia, and/or findings on ultrasonography. At the same time, insulin and glucose concentrations were measured before surgery for clinical diagnosis. Although all cases displayed typical clinical signs and hypoglycemia, insulin concentrations varied with 3 of 8 cases showing levels within the reference interval. In addition, to confirm the reliability of measured values, we submitted serum samples from 4 cases to two commercial veterinary laboratories. Results differed considerably between laboratories, with no apparent correlations between the two. In Laboratory A, 3 of 4 cases were above the reference interval, and 1 case was in the middle of the reference interval. Conversely, in Laboratory B, 3 of 4 cases were above the reference interval, and 1 case was below the reference interval. Split decisions regarding the diagnosis of insulinoma were seen for 2 of the 4 cases.

Quality Control Validation, Application of Sigma Metrics, and Performance Comparison between Two Biochemistry Analyzers in a Commercial Veterinary Laboratory

A review of the literature pertinent to interpretation of biochemistry data and quality control (QC) and proficiency testing data from 2 biochemistry analyzers was used to determine clinical quality requirements for biochemistry assays, characterize the performance of and calculate sigma metrics for the analytes run on the 2 analyzers, and perform QC validation in order to determine the needs for statistical QC for each analyzer. Quality requirements suitable for the analytes based on the needs of the authors' laboratory are presented. These requirements may or may not be appropriate for other laboratories, depending on the needs of the clients, species, and equipment performance capability. The majority of the analytes were easily controlled using the 1(3s) control rule, with a sigma metric approaching or exceeding 6 and with a high probability of error detection and a low probability of false rejection. Some analytes could not be controlled using the 1(3s) rule, and additional control rules with a greater number of control data points were required. There were differences between performances of the 2 analyzers. The findings in the present study emphasize the need for QC specific for the analyte and the clinical decision level and the need for separate QC validation on every instrument.

Isolation of Malassezia pachydermatis and M. sympodialis from the external ear canal of cats with and without otitis externa

The objective of this study was to determine the presence of Malassezia spp. in the external ear canal of cats with and without otitis. Forty-five animals were studied, 20 with and 25 without otitis externa (OE). Cerumen or secretion from external ear canal samples was cultured on modified Mycosel agar and sterile olive oil was added to the surface of the medium before specimen seeding. The isolates were analysed for macro- and micromorphology and identified by catalase tests and on the basis of growth on Tween 20, 40, 60 and 80. Malassezia spp. were isolated from 15 out of 20 (75%) animals with otitis and from 7 out of 25 (28%) cats without OE; the difference between the two groups was statistically significant (P < or = 0.05). Malassezia pachydermatis and M. sympodialis were isolated from 60% (12/20) and 40% (8/20) of cats with otitis, respectively, with no significant difference in the frequency of isolation between the two species. In the microflora of the healthy ear canal M. pachydermatis was significantly more common (6/25, 24%) than M sympodialis (1/25, 4%). The present investigation confirms that M. sympodialis can also act as an aetiological agent of feline OE, and if commercial veterinary laboratories do not use media with added lipids for the isolation of Malassezia spp., this might lead to false-negative results.

The Effectiveness of Current Sterility Techniques in Natural Orifice Transluminal Endoscopic Surgery (NOTES)

Background: NOTES represents a potentially less invasive alternative to conventional laparoscopy. However, breach of the gut wall raises the specter of intra-peritoneal infection. Various anti-microbial techniques have been employed in animal survival studies—including sterile saline rinse, intravenous and topical antibiotics, and Betadine—despite a paucity of data regarding their general effectiveness. Aim: To assess the effectiveness of existing sterilization techniques for NOTES by quantifying and speciating colony-forming units (CFU's) before and after treatment in ex vivo porcine organs. Method: Stomachs and distal colons were harvested en bloc from six fasted adult female white pigs following euthanasia. Four of these animals received 1g of Cefazolin intravenously prior to sacrifice. After the organs were filleted open in sterile fashion, they were further sub-divided into 2.0 cm × 2.0 cm full-thickness square samples. Each tissue sample was then assigned to one of five treatment arms: (1) sterile 0.9% saline lavage, (2) Betadine lavage, (3) lavage with a Cefazolin/Metronidazole suspension, (4) 4% Chlorhexidine lavage, or (5) no treatment. Following 10 minutes of contact time with the treatment solution, the mucosal surface of each tissue sample was swabbed with a sterile cotton applicator and inoculated in 5 ml of normal saline for 1 hour, followed by serial dilutions. 100 mL aliquots of each dilution were plated onto Sheep's blood agar plates and incubated in aerobic conditions at 24 degrees Celsius. Colony-forming units (CFU's) were quantified after seven days, and representative samples were sent to a commercial veterinary laboratory for speciation. Results: Initial bacterial density was estimated to be 1.0 × 106 CFU's/cm2 for stomach and 1.2 × 106 CFU's/cm2 for colon. The predominant organisms were Escherichia coli in stomach and both Escherichia coli and Enterococcus sp in colon. Sterile normal saline lavage caused a 1-log reduction to 2.3 × 105 CFU's/cm2. Antibiotic lavage caused a 2-log reduction to 6 × 104 CFU's/cm2. Betadine lavage a 5-log reduction to 4.1 × 101 CFU's/cm2. Finally, Chlorhexidine lavage also caused a 5-log reduction to 6.0 × 101 CFU's/cm2. The use of intravenous antibiotics alone diminished bacterial load to 10 CFU's/cm2. The combined use of intravenous antibiotics and Betadine or Chlorhexidine decreased counts to zero. Data was analyzed using ANOVA 2-way analysis method and found to be statistically significant (P = 0.001). Conclusions: The use of intravenous antibiotics in addition to topical Betadine or Chlorhexidine effectively eradicated bacteria in both gastric and colonic mucosa in this porcine model.

Antithrombotic and Fibrinolytic Factors: A Review

Excessive or nonphysiologic thrombogenesis and fibrinolysis accompanies many diseases. Several specific proteins involved in the physiologic regulation and maintenance of blood in a fluid state are reviewed in this article. Assays for these proteins or evidence of their function (antithrombin III, protein C, protein S, plasminogen/plasmin, tissue plasminogen activator, plasminogen activator inhibitor I, fibrinogen/fibrin degradation products, and thrombin/antithrombin complexes) are described. Principles, general methodology, and application in veterinary medicine are discussed. Although most of the investigative work and knowledge concerning these proteins and assays has been in human beings, their use and application in veterinary medicine is becoming more available in research laboratories at referral centers and some larger commercial veterinary laboratories. Use and interpretation of these assays will help clinicians and researchers better understand pathophysiologic processes occurring in various diseases associated with thrombogenesis and excessive fibrinolysis.

Fructosamine concentrations in hyperglycemic cats

The aims of this study were 1) to establish a reference range for fructosamine in cats using a commercial fructosamine kit; 2) to demonstrate that the fructosamine concentration is not increased by transient hyperglycemia of 90 min duration, simulating hyperglycemia of acute stress; and 3) to determine what percentage of blood samples submitted to a commercial laboratory from 95 sick cats had evidence of persistent hyperglycemia based on an elevated fructosamine concentration. Reference intervals for the serum fructosamine concentration were established in healthy, normoglycemic cats using a second generation kit designed for the measurement of the fructosamine concentration in humans. Transient hyperglycemia of 90 min duration was induced by IV glucose injection in healthy cats. Multisourced blood samples that were submitted to a commercial veterinary laboratory either as fluoride oxalated plasma or serum were used to determine the percentage of hyperglycemic cats having persistent hyperglycemia. The reference interval for the serum fructosamine concentration was 249 to 406 mumol/L. Transient hyperglycemia of 90 min duration did not increase the fructosamine concentration and there was no correlation between fructosamine and blood glucose. In contrast, the fructosamine concentration was correlated with the glucose concentration in sick hyper- and normoglycemic cats. It is concluded that the fructosamine concentration is a useful marker for the detection of persistent hyperglycemia and its differentiation from transient stress hyperglycemia. Fructosamine determinations should be considered when blood glucose is 12 to 20 mmol/L and only a single blood sample is available for analysis.