Recognition in Great Britain of Bacteroides nodosus in foot lesions of cattle

Characterization of the predominant anaerobic bacterium recovered from digital dermatitis lesions in three Michigan dairy cows

Digital dermatitis is a superficial epidermatitis of the feet of cattle. Data from previous work suggest that spirochaetes, Campylobacter spp., and Bacteroides spp. may be important in the disease, but the etiology of this disease is not entirely clear. Tissue samples collected from digital dermatitis lesions in three Holstein-Friesian cows from a Michigan dairy yielded a predominant colony type when incubated anaerobically on blood agar at 35 degrees C for 24-48 h. The isolate was a non-flagellated Gram-negative rod, 7 microM long and <0.5 microM wide; its growth was strictly anaerobic and resulted in slight ss-hemolysis on blood agar; 16S rRNA gene sequence analysis indicated it belonged to the cytophoga-flexibacter-bacteroides phylum. The finding that this bacterium was the predominant anaerobe recovered from digital dermatitis lesions suggests it may be involved in the digital dermatitis disease process.

A role for DNA characterisation in ovine footrot

Bacteroides nodosus involved in several outbreaks of ovine footrot over a number of years were subjected to DNA restriction endonuclease analysis. Individual isolates were found to have characteristic Bam HI profiles which permitted their accurate identification and differentiation from other isolates. Bam HI profiles of B. nodosus isolates were used in epidemiological investigations involving consecutive outbreaks of footrot on individual and neighbouring farms. The relationship of given isolates to a common source could be established by this means. Restriction endonuclease analysis provides an additional epidemiological tool in ovine footrot investigations as it accurately identifies interstrain differences in a manner not possible by conventional bacteriological and serological means.

Failure of oral zinc therapy to alleviate Bacteroides nodosus infections in cattle and sheep

Cattle and sheep with Bacteroides nodosus infection were treated orally with both high (65 mg Zn/kg and 82 mg Zn/kg) and low (1 mg Zn/kg and 8.6 mg Zn/kg) doses of zinc sulphate respectively. The lower dose rates administered weekly for one month, in the case of cattle, or daily for 2 weeks, in the case of sheep, had no effect either on serum zinc levels or the prevalence or severity of infection in treated animals. High dose rates of zinc (approximately 2.5 g Zn per head per day) were required to elevate serum levels above those normally present in both cattle and sheep. Even these dose rates continued daily for about 2 weeks had no beneficial effect on B. nodosus infection in either species.

Twenty-five years of progress in understanding major infectious diseases of dairy cattle

Disease, whether it occurs in cats, cattle, caribou, or other species, is the manifestation of insult to the structural or functional integrity of the living being. Infection may occur with or without evidence of disease. Disease may represent only the “tip of the iceberg” of infection.

Prevalence of disease is the proportion of a defined population that meets specific criteria at a point in time, and incidence refers to the proportion of a defined population in which the onset occurs during a specifiable interval. Risk is an instantaneous rate of incidence.

Prevalence, incidence, and risk in infectious diseases are quantitative inferences derived from assessment of implications — caveats derived from variables that often are elusive, such as antibiotic resistance to plasmid mediated determinants transferable between species of enteric bacteria, or such as increases in population density among insect vectors influenced by climatic conditions favorable to the insects. Carefully orchestrated manipulation of the etiologic agent or the host response is made possible by ever-expanding understanding of the molecular biology of pathogenicity on the one hand and cellular and humoral immunity on the other. Such understanding often leads to new caveats or destroys old ones based on incomplete information.

This paper deals with a selected limited number of infectious diseases of dairy cattle. Knowledge developed around the cited parameters in 13 infectious diseases during the past quarter century is brought into focus. Ten geographically dispersed specialists in infectious diseases of cattle were asked to identify priorities among the array of transmissible diseases important to North America. Except for the mastitis syndrome, which will be given special attention elsewhere in these anniversary papers, the diseases discussed are those wherein major advances in knowledge or major needs for advanced knowledge were of special importance.

Isolation and characterisation of Bacteroides nodosus from foot lesions of cattle in Western Australia

Thirty one isolates of Bacteroides nodosus were obtained from foot lesions observed on cattle at 3 abattoirs. All isolates were similar to the B. nodosus of ovine benign footrot (BFR) in their response to the degrading proteinase test. At one abattoir, where the interdigital lesions were examined in detail, 9 of 10 isolates were obtained from hyperkeratotic lesions with deep fissures. Traceback to 8 of the farms of origin which carried both sheep and cattle, revealed BFR in sheep on 4 farms. The significance of B. nodosus in interdigital lesions in cattle, and its possible pathogenicity, are discussed.

Aspects of anaerobic infections in animals

The recent literature on clostridial infections of animals and infections due to gram-negative anaerobic rods is reviewed. It is stressed that quite recently the literature is concerned with animal models for the evaluation and study of the chemotherapy, immunity mechanisms and pathogenesis of Fusobacterium and Bacteroides infections in animals came into being.