Detection of bacterial contamination and DNA quantification in canine and feline stored blood units.

INTRODUCTION: Blood transfusions in veterinary medicine have become increasingly more common and are now an integral part of lifesaving and advanced treatment in small and large animals (1).Several guidelines suggest what infectious agents to screen for in canine and feline transfusion medicine (2,3).While the risk of bacterial contamination of blood products during collection, processing, storage and administration is not considered in veterinary medicine, it has emerged as a cause of morbidity and mortality in human transfusion medicine. AIM OF THE STUDY: The purpose of this report is to describe the detection and quantification procedures applied in four cases of bacterial contamination of canine and feline blood units, which suggest the need of further investigative studies and monitoring to optimize patients’safety in veterinary transfusion medicine. MATERIALS AND METHODS: Four red blood cell units which showed a color change were included in the present report. The first one (case A) was collected from a 3-year-old female mongrel dog from a Blood Bank; the second one (case B) from a 7-year-old male mongrel dog, the third one (case C) from a 3-year-old male mongrel dog, and the last one (case D) from a 7-year-old male European cat, from another Blood Bank. The blood was collected from healthy animals according to the guidelines and immediately refrigerated in a blood-storage refrigerator at 4 °C, where it can be stored up to 40 days.The massive visible color changes were noted at day 31 of storage in case A, at day 20 in cases B and C and day 32 in case D. These units were removed from the Blood Bank for further investigations. Microscopic evaluation of a smear from each of the blood bags revealed heavy bacterial contamination.DNA was isolated from each of the blood bags and bacterial DNA load per sample was assessed by qPCR modifying Nadkarni et al procedure(4). The bacterial Genome Equivalent number (GE/mL of template) was 1.18 x107 GE/mL in case A, 3.64 x107 GE/mL in case B, 8.38 x107 GE/mL in case C and 5.22 x108 GE/mL in D. PCR products were purified and after alignments in the EMBL GenBank database, the sequences matched perfectly with Serratia liquefaciens in A, Pseudomonas putida in B and C, and Pseudomonas fluorescens in D. CONCLUSIONS: The current study showed that bacterial contamination was present and with high bacterial DNA load. These findings confirm data of human transfusion medicine. Instead, when reviewing the veterinary literature, actual reports of bacterial contamination of blood bags are remarkably rare and many post-transfusion reactions could probably be misdiagnosed or overlooked.Since thousands of blood transfusions are performed each year on dogs and cats and the demand for blood products continues to grow (5), the present report emphasizes the importance of carefully designed protocols to prevent bacterial contamination of blood collected for transfusion and to optimize patients’ safety in veterinary transfusion medicine. REFERENCES: 1 Tocci LJ, Ewing PJ. J Vet Emerg Crit Care. 2009;19(1):66-73. 2 Italian Health Minister. Guide Line relating to the exercise of the health activity concerning the transfusion medicine in the veterinary field. 3 Reine NJ. Clin Tech Small Anim Pract. 2004;19(2):68-74. 4 Nadkarni et al. Microbiol Read Engl. 2002;148(Pt 1):257-266. 5 Wardrop KJ et al. J Vet Intern Med Am Coll Vet Intern Med. 2005;19(1):135-142.