Isolation of Abiotrophia spp. with Staphylococcus aureus in a case of mastitis in a cow.
Isolation of Streptococcus suis from a young wild boar C treptococcus suis is an important pathogen of pigs, which has also been recognized as a zoonotic agent (1). Streptococcus suis has been associated with sporadic infections in a variety of mammalian species, such as, cattle, bison, horses, sheep, goats, dogs, and cats (2). It has recently been isolated from psittacine birds, zebrafinches, canaries, bullfinches, and a duck (2). A 20-day-old, wild boar from a 30-sow herd was submitted to the Faculte de medecine vet6rinaire of the Universit6 de Montr6al with signs of pneumonia and diarrhea. The animal was alert and did not show any neurological signs. The boar was euthanized; at necropsy, the cranial lobes of the lung, particularly on the the right side, were firm textured. The caudal lobes of the lung were not affected. There was no evidence of arthritis. Microscopic examination of the lung revealed suppurative bronchopneumonia with hemorrhagic foci and fibrinous exudation. A moderate number of coccidia were seen in sections of the small intestine. Bacteriological cultures of lungs yielded Streptococcus suis capsular type 2 colonies in large numbers, as well as a comparable number of colonies of Escherichia coli. The E. coli isolated from the intestines did not possess any of the enteropathogenicity virulence factors, and tests for rotavirus and coronavirus were negative. A total of 3 litters in this herd showed signs of infection with Streptococcus suis. Marked clinical improvement was noted after pigs from these litters were injected with 300,000 units of procaine penicillin G. The origin of the infection was not determined, but there is speculation that it spread from a swine herd on the same farm.
Transfer of Streptococcus adjacens and Streptococcus defectivus to Abiotrophia gen. nov. as Abiotrophia adiacens comb. nov. and Abiotrophia defectiva comb. nov., respectively.
We performed this study to determine the 16S rRNA sequences of the type strains of Streptococcus adjacens and Streptococcus defectivus and to calculate the phylogenetic distances between these two nutritionally variant streptococci (NVS) and other members of the genus Streptococcus. S. adjacens and S. defectivus belonged to one cluster, but this cluster was not closely related to other streptococcal species. A comparative analysis of the sequences of these organisms and other low-G+C-content gram-positive bacteria revealed that the two NVS species formed a distinct cluster and were only remotely related to the Aerococcus and Carnobacterium clusters. The highest level of homology (93.7%) was found between S. adjacens and Carnobacterium divergens. Carnobacterium species have meso-diaminopimelic acid in their cell walls, but S. adjacens and S. defectivus have L-lysine as the diamino acid at position 3 in their peptidoglycan tetrapeptides. On the basis of our findings and the results of previous phenotypic studies, we propose that the NVS species should be placed in a new genus, the genus Abiotrophia, as Abiotrophia adiacens comb. nov. and Abiotrophia defectiva comb. nov.
Satellite streptococci. A major cause of "negative" blood cultures in bacterial endocarditis?
In three of the 20 patients with bacterial endocarditis in our institution since 1975, satellite streptococci were recovered from the blood stream (15%). These organisms do not grow under usual laboratory conditions and may only be demonstrable after fortuitous contamination of the media. Clinicians and microbiologists must be alert to the possibility of satellite streptococci in patients with suspected bacterial endocarditis, and measures should be instituted to identify the organism.