Cuticular Lesions of Ascaris suum Caused by Pseudomonas sp.

Abstract

Three microorganisms were cultured from cuticular lesions of Ascaris suum: Escherichia coli, Candida sp., and Pseudomonas sp. In in vitro and in vivo trials the lesions were reproduced on ascarids only by Pseudomonas sp. The cuticular lesions are yellow-brown spots and are sometimes present in numbers. The cuticle is necrotic, thickened, and eroded. The lesions are craterlike in section, raised peripherally and depressed centrally. The Pseudomonas sp. does not appear to be similar to any of the organisms previously reported from swine ascarids and is not identical with any of the well-described species of Pseudomonas. Weinberg and Keilin (1912) described cuticular lesions from numerous specimens of Parascaris equorum. The lesions were hard, yellowish plaques, sometimes single and at other times numerous and lineally confluent. Large cocci were isolated from one of these lesions and recovered many times from the perienteric fluid of diseased ascarids. Liibinsky (1931) observed the same type of lesion in eight species of nematodes: Parascaris equorumrn, Ascaris suum, A. lumbricoides, Toxascaris limbata, Heterakis perspicillum, Oxyuris curvula, Strongylus equinus, and S. vulgaris. Manter (1929) described cuticular lesions of ascarids taken from swine in Nebraska that were associated with an organism resembling Clostridium welchii. Epps et al. (1950) made repeated isolations of unidentified gram-negative rods from A. suum. Bird and Deutsch (1958) reported Pseudomonas aeruginosa to be commonly present in the cuticular grooves of A. suum. Emanuilov (1957) studied the interrelationships between bacteria and ascarids of the pig and horse. He considered Bacterium mesentericus to be antagonistic to ascarids. He also isolated Pseudomonas pyocyanea and Escherichia coli from all ascarids studied. On several occasions A. suum obtained at Tifton, Georgia, have been found with yellowbrown spots on the cuticle, sometimes in such numbers as to give the appearance of polka dots (Fig. 1). These lesions appeared to be indistinguishable from those described by Weinberg and Keilin and from those photographed by Liibinsky. On 7 February 1958 large numbers of lesions were noted on the cuticles of the majority of ascarids recovered from a group of experimental pigs at the Georgia Coastal Plain Experiment Station, Tifton, Georgia. An investigation was begun in an attempt to identify the causative organism and determine its pathogenicity. A preliminary report of the investigation was published by Stewart and Godwin (1959). MATERIALS AND METHODS Ordinary bacteriological methods were employed in isolating microorganisms from the cuticular lesions. The following media were used: (1) heart infusion broth, (2) blood agar, (3) mannitol salt agar, and (4) semisolid thioglycollate. Organisms growing in the above media were transferred to heart infusion broth, tryptone agar slants, or microphil agar slants, depending on the characteristics of the organisms involved. All infection trials and biochemical tests were made with 24-hr broth cultures. Ascarids obtained from swine at a local abattoir were examined for lesions under a dissecting microscope, washed repeatedly in sterile physiological salt solution if free of lesions, and incubated overnight in physiological salt solution containing 500 units/ml each of penicillin and streptomycin. In trial 1 no antibiotics were used. The following Received for publication 3 October 1962. * Present address: College of Veterinary Medicine, University of Illinois, Urbana, Illinois.