Use of oligodeoxynucleotide probes to verify Campylobacter jejuni as a cause of bovine abortion.

Abstract

Campylobacter abortions in bovines are usually caused by Campylobacter fetus subsp. venerealis or Campylobacter fetus subsp. fetus 8,15 Bovine abortions caused by C. jejuni are unusua1. Between February 1988 and February 1991, 4 bovine Campylobacter abortions were diagnosed at the Iowa State University Veterinary Diagnostic Laboratory. Based on biochemical profiles, 3 were identified as Campylobacter jejuni and 1 was identified as Campylobacter coli. The identification of species of Campylobacter is difficult because of its fastidious growth requirements and few differential biochemical tests. For Campylobacter, the type of basal medium and the density of the inoculum may explain discrepancies observed in resistance to chemical compounds, temperature tolerance, and necessary growth conditions. Because phenotypic traits and biochemical profiles may not adequately differentiate Campylobacter species, nucleic acid probes offer an alternative to biochemical tests. Nucleic acid probes have been developed for a number of species of Campylobacter, including Campylobacter jejuni a and Campylobacter fetus. 14 The goal of this study was to apply nucleic acid probes to verify the identity of the C. jejuni isolate designated VDL 4410. Isolate VDL 4410 was recovered from the placenta of a Hereford cow that aborted in the last trimester of pregnancy. Serum from the cow and tissues from the aborted fetus and a portion of the placenta were received by the Iowa State University Veterinary Diagnostic Laboratory within 24 hours of the abortion. The serum sample from the cow had no detectable titer for leptospirosis or bovine viral diarrhea virus. Samples of placenta and fetal lung, liver, and kidney were fixed in 10% neutral buffered formalin. Tissues were dehydrated in graded alcohols, cleared, embedded in paraffin, cut at 4 μm, and stained with hematoxylin and eosin (HE) and Gram’s stain for light microscopy. Microscopic examination of the HE-stained sections of the placenta revealed numerous trophoblasts sloughing from the fetal chorionic villi and large accumulations of polymorphonuclear (PMN) leukocytes on the surface of the chorionic villi. There were a few small scattered groups of PMN leukocytes in the stroma of the chorionic villi. A Gram stain revealed smudged colonies of gram-negative bacteria in some of the chorionic villus trophoblasts and in capillaries scattered throughout the chorionic stroma. A few curved bacteria could be identified, but the morphology of most of the organisms was too distorted for identification purposes. There were no microscopic lesions in the lung, liver, kidney, or spleen. Swabs of placental cotyledon and fetal lung, liver, and