Documentation of an infectious agent in blood smears by cytologic examination requires skilled personnel, is time consuming (an adequate blood film examination can take 20–30 minutes), and lacks sensitivity for most pathogens. False positives can also occur, such as when staining artifacts are confused with micro‐organisms. Therefore, cytologic examination of blood smears is not recommended as the sole means of screening blood donors for infection.

Positive blood culture results indicate the presence of cultivable bacteria in the blood. Although transient bacteremia can occur in healthy animals after disruption of mucosal barriers, transfusion of blood from animals with transient bacteremia has not been documented to cause disease in a recipient. Therefore, routine blood culture generally is not indicated for screening potential blood donors, with rare exceptions (see Bartonella section). In transfusion medicine, routine blood culture is more appropriate for screening individual units of blood for bacteria if contamination is suspected.

Filippo Ferri1, Silvia Ferro2, Edoardo Auriemma1, Massimo Castagnaro2, Luigi Michele Coppola3, Andrea Peano4, Vito Martella5, Nicola Decaro5, Eric Zini6

1Istituto Veterinario di Novara, Granozzo con Monticello, Novara, Italy, 2Department of Comparative Biomedicine and Food Sciences, University of Padova, Legnaro, Padova, Italy, 3Department of Animal Medicine, Production and Health, University of Padova, Legnaro, Padova, Italy, 4Department of Veterinary Science, University of Turin, Grugliasco, Turin, Italy, 5Department of Veterinary Medicine, University of Bari, Valenzano, Bari, Italy

6Vetsuisse Faculty, University of Zurich, Zurich, Switzerland

In dogs splenitis is rarely described. The few reported cases have been associated to splenic abscesses or pseudotumor, and systemic mycosis. The aims of this study were to define the prevalence of splenitis in dogs, describe clinical findings and outcome, characterize histological patterns of splenic inflammation and investigate possible causes.

Formalin‐fixed, paraffin‐embedded splenic samples of dogs with a diagnosis of splenitis were gathered from the pathology archive, between 2005–2013. New slides were obtained and stained with hematoxylin‐eosin, Gram, green‐Gram, Giemsa, periodic acid‐Schiff (PAS), Ziehl‐Neelsen. Slides were examined by two pathologists. Furthermore, an aliquot of each specimen was processed for PCR analysis to detect bacterial, fungal or protozoal DNA. Dog owners were contacted to achieve information pertaining clinical findings and outcome.

Of 660 available splenic samples, 33 (5%) had a histological diagnosis of splenitis. Clinical findings and outcome were available in 19 dogs (57.6%). Presenting complaints were weakness in 16 dogs (48.5%), fever in 11 (33.3%) and abdominal effusion in 7 (21.2%). Sixteen (48.5%) of them survived to discharge following splenectomy, with or without additional abdominal surgery; the remaining three dogs died between 7 and 40 days from admission. Splenic histological findings in the 33 dogs included neutrophilic (36.4%), granulomatous (33.3%), haemorrhagic (18.3%) or lymphocytic (6%) splenitis and splenic abscess (6%). Based on clinical records or necropsy findings, 21 dogs (63.6%) had concurrent diseases along with splenitis, including 4 each with gastric dilation‐volvulus or neoplasia, 2 each with granulomatous hepatitis or pyometra, and 1 each with hepatic lobar torsion or systemic mycosis. In seven dogs (21.2%) bacteria were identified in the spleen based on histology (four dogs with Gram+ cocci, and 1 each with Gram‐ cocci or Gram+ cocci and bacilli) or bacterial culture (one dog with Pseudomonas aeruginosa). In three dogs (9.1%) protozoa were identified by PCR (three dogs with Leishmania infantum) or histology (1 of the Leishmania‐positive dogs had concurrent Hepatozoon canis) and in one dog (3%) ifae were detected with histology. PCR did not identify bacteria or fungi in any of the spleen, including those with microscopic evidence of infection. Associations between histological findings and causes were not observed.

The present study shows that splenitis is an uncommon disorder in dogs. Splenitis is frequently secondary to inflammation of other organs or to systemic infections, although in numerous dogs it may not be associated with other obvious diseases. Prognosis is favourable in the majority of affected dogs. Several histological patterns of inflammation are identified in dogs with splenitis but whether they reflect different causes deserves further studies. PCR may not be a sensitive tool to detect bacteria and fungi DNA in formalin‐fixed, paraffin‐embedded splenic samples.

Nancy Sanders1, Christian Leutenegger2, Jane Robertson2, Marko Estrada2, Pauline Young2

1IDEXX Laboratories, Inc., Westbrook, ME, USA, 2IDEXX Laboratories, Inc., Sacramento, CA, USA

Definitive diagnosis of feline infectious peritonitis (FIP) remains a challenge. Difficulties in diagnosis include lack of specific clinical signs, non‐specific laboratory abnormalities and low specificity of antibody titers. A real‐time PCR test to detect the specific virulent form of feline coronavirus has recently been developed by IDEXX Laboratories based on fusion peptide mutations in the spike gene. FIP Virus RealPCR® Test is reported as one of two biotypes: feline infectious peritonitis (FIPV) or feline enteric coronavirus (FECV). When biotyping is not possible on a specimen, it is reported as either below limit of detection or indeterminate, depending on the viral load.

Fifty domestic cats initially suspected by the submitting veterinarian to have FIP were included in the study. Cats ranged in age from 2 to 195 months (2 months to 16 years). The majority of cats (41) were 2 years or younger; 6 cats were adult (3–11 years of age); and 3 were geriatric (14–16 years). Breeds represented were domestic shorthair (37), domestic longhair (5), Burmese (2), and one each of Bengal, Persian, American Shorthair, Ragamuffin, and unknown breed. The cases were graded by a boarded internal medicine specialist with a clinical scoring system ranging from 1 (confirmed not FIP) to 6 (confirmed FIP). Cases graded 1–3 were unlikely, and 4–6 were likely to have FIP. The clinical grading scale included specific information such as history, signalment, and all available laboratory diagnostic test results. Cats graded as 6 were confirmed to have FIP based on histopathology and immunohistochemical staining for coronavirus.

Of the 50 cats initially suspected of having FIP, 3 were determined unlikely to have FIP based on the grading system (grade 3 or less). None of these cats obtained a FIPV biotype result. Three of 50 cats were unable to be graded given available data. The remaining 44 cats were graded likely to have FIP (grade 4 or higher). Of these 44 cats, 24 (54%) had an FIPV biotype result on one or more samples. None of the 44 cats had a FECV biotype result. Twenty of the cats had viral loads below the limit of detection.

FIPV biotype positive results were obtained from 4/20 (20%) whole blood samples, 3/3 (100%) pericardial effusions, 5/6 (83%) pleural effusions, 11/23 (48%) peritoneal effusions, 1/1 (100%) aqueous humor sample, and 1/1 (100%) aspirate of an abdominal lymph node. For cats with one or more biopsies submitted, 18/18 cats (100%) had at least one biopsy sample positive for the FIPV biotype. Tissues with the highest rate of FIPV biotype were spleen, omentum and mesenteric lymph nodes. Other tissues positive for FIPV biotype included pancreas, bladder wall, eye, heart, liver, kidney, and lung. It is also noted that tissues with the most obvious gross pathology were more likely to provide a FIPV biotype result.

The results of this study show that the FIP Virus RealPCR Test can be used to confirm the diagnosis of FIP in clinically suspect cats but that the sensitivity of the test appears to be highly dependent on the specimen submitted. Whole blood was the specimen least likely to provide a positive biotype result. Abdominal effusion specimens had a moderate sensitivity. Testing of pleural effusion specimens, tissue aspirates and biopsy samples (especially of spleen, omentum and mesenteric lymph nodes) provided the highest likelihood of a positive biotyping result.

L. Solano‐Gallego1, I. Casanova2, S. Martin1, A. Marco2

1Universitat Autònoma de Barcelona, Bellaterra, Spain,2Servei de Diagnostic Patologia, UAB, Bellaterra, Spain

Previous studies have demonstrated Leishmania infantum infection in colonic samples with histiocytic or lymphoplasmacytic inflammation from seropositive sick dogs. However, there are no studies that have investigated the presence of L. infantum infection in dogs diagnosed with inflammatory bowel disease (IBD) by clinical and histopathological examination. The objectives of this study were to retrospectively investigate the presence of Leishmania infection by immunohistochemistry (IHC) in archived canine colonic biopsies previously diagnosed with IBD in an area endemic for canine leishmaniosis as well as to describe the main histopathological findings. A total of 109 cases of canine colitis were retrospectively retrieved from the archived of biopsies of Servei de Diagnòstic de Patologia of the Universitat Autònoma de Barcelona. Information regarding clinicopathological data including signalment, histological results and further diagnostic testing to detect Leishmania infection such as Leishmania IHC staining was compiled from the selected cases. Lymphoplasmacytic (n = 101), histiocytic (n = 5), and lymphoplasmacytic with mild eosinophilic/neutrophilic component (n = 3) colitis were diagnosed between January 1997 and September 2015 performed by endoscopic colonic biopsies. Interestingly, Leishmania IHC was only carried out in 13 out of 109 (11.9 %) colonic samples to confirm or exclude Leishmania infection based on the diagnostic database. From those, 5 were diagnosed as granulomatous and 8 as lymphoplasmacytic colitis. Four biopsies were classified as positive, two as unclear results due to unspecific background staining and the rest were negative for Leishmania IHC. Leishmania IHC was performed in 56 out of the remaining 96 colonic samples with a diagnosis of lymphoplasmocytic or histiocytic inflammation that were not previously tested to confirm or exclude this infection. Due to economical restrictions, only 56 colonic samples retrieved could be investigated. Only one out of 56 (1.8%) colonic biopsies examined was classified as positive by IHC. A total of 5 out of 109 (4.6%) dogs were diagnosed with Leishmania infection. Two dogs presented intense histiocytic inflammation while three dogs showed mild to intense lymphoplasmacytic inflammation. The number of amastigotes per 5 microscopic fields viewed at 40× assessed by IHC was variable and ranged between 2 to countless. In conclusion, Leishmania infection should be included in the list of differentials of inflammatory colonic biopsies. Leishmania amastigotes are commonly not visualized by routine histological staining. Therefore, IHC for Leishmania should be routinely used as a diagnostic tool in endemic areas of leishmaniosis, to exclude or confirm an infection by this parasite in patients with a diagnosis of IBD.

Disclosures

No disclosures to report.

N.R. Barash, A.J. Birkenheuer, J. Megan

North Carolina State University, Raleigh, USA

Bloodstream infections are a substantial cause of morbidity and mortality in critically ill veterinary patients. Blood cultures are the gold standard for diagnosis of bacteremia, but are infrequently obtained due to technical and practical difficulties in sample acquisition. In ill patients, urine cultures are sometimes recommended as surrogates for blood cultures as part of a “better than nothing” approach. This study evaluated the ability of urine culture to predict blood‐stream infection. We retrospectively evaluated all blood, aerobic, and anaerobic cultures submitted at NC State Veterinary Hospital between 2011 and 2016. We calculated growth rates of 18% (blood), 24% (urine), and 61% (non‐urine) from 511 blood, 6797 urine, and 6552 non‐urine cultures submitted. Blood isolates were most commonly coagulase‐positive Staphylococcus spp (27%) and Escherichia coli (14%); Escherichia coli was the most common urinary isolate (43%), along with Enterococcus (14%) and coagulase‐positive Staphylococcus (11%). 324 urine and blood samples were submitted in parallel, of which 21 yielded simultaneous growth. Of these, only 14 samples were concordant, while 7 yielded discordant urinary and bloodstream infections. Overall, urinary isolates were poorly reflective of bloodstream isolates, with a sensitivity of 24% but a specificity of 87%. General concordance, including true positive (n = 14) and true negatives (n = 232), between urinary and bloodstream isolates was 76%. Urine culture isolates had a poor positive predictive value (29%) but a negative predictive value of 84% for bloodstream infection. An apparent exception is patients with suspected urogenital infection sources (renal, prostatic, etc), in which 100% (n = 7) had concordant urinary and bloodstream infections. Coagulase‐positive Staphylococcus infections were most likely to be concordant. 133 non‐urine samples submitted in parallel with blood cultures were also evaluated; only biliary and intravenous catheter samples carried a PPV >40%. In short, we recommend that if bloodstream infection is suspected, blood cultures be acquired. Coagulase‐positive Staphylococci, if isolated from urinary tract of ill patient, should raise clinical suspicion of a potential concordant bloodstream infection. Due to a high discordance rate, in particular, blood cultures should be performed in any potentially septic animal who is immunosuppressed. Bacteriuria is neither a substitute nor a screen for bacteremia, and in fact, based off of our calculated false negative rate, treatment of urinary tract pathogens in likely bacteremic animals would lead to treatment for the incorrect bloodstream pathogen 76% of the time. Though urine cultures are encouraged as part of a complete diagnostic workup, they do not substitute for blood cultures.

Disclosures

Disclosures to report.

Jacob ME: Director of NCSU Clinical Microbiology Laboratories. No other disclosures to report.