Antibiotic susceptibility of Fusobacterium necrophorum isolated from liver abscesses

Antibiotic susceptibility patterns of thirty-seven isolates of Fusobacterium necrophorum (21 biotype A and 16 biotype B) from liver abscesses of feedlot cattle were determined. These isolates were generally susceptible to penicillins, tetracyclines (chlortetracycline and oxytetracycline), lincosamides (clindamycin and lincomycin), and macrolides (tylosin and erythromycin) but resistant to aminoglycosides (kanamycin, neomycin, gentamycin and streptomycin), ionophores(except narasin), and peptides (avoparcin, polymixin, and thiopeptin). Differences in antibiotic sensitivity patterns were observed between the two biotypes only for clindamycin and lincomycin. The minimum inhibitory concentrations (MIC) of FDA-approved antibiotics for liver abscess control did not parallel their efficacy in preventing clinical liver abscesses in feedlot cattle. Continuous tylosin feeding did not appear to induce antibiotic resistance in F.necrophorum

Experimental induction and monitoring of liver abscesses in cattle with ultrasonography

We have demonstrated that ultrasonography can be used to visualize liver abscess in live cattle. We have also developed a nonsurgical method of catheterizing the bovine portal vein and experimentally inducing liver abscesses by inoculating the portal vein with Fusobacterium necrophorum bacteria

Bacteriological and histopathological investigations of liver abscesses

Fusobacterium necrophorum was the predominant bacterial isolate from 49 liver abscesses. Biotype A tended to occur in pure infections and produced a more severe tissue reaction than biotype B, which tended to occur as a mixed infection

Fusobacterium necrophorum leukotoxoid vaccine for prevention of liver abscesses

The efficacy of Fusobacterium necrophorum crude leukotoxoid vaccine to immunize and protect steers against experimentally induced liver abscesses was evaluated. The vaccine consisted of cell-free culture supernatant of a high leukotoxin-producing strain of F. necrophorum, inactivated with formalin and homogenized with an oil emulsion adjuvant. Vaccine was injected subcutaneously on days 0 and 21. Blood samples were collected weekly to monitor immune response. Three weeks after the second vaccination, steers were injected intraportally with F. necrophorum culture to induce liver abscesses. Three weeks later (day 63), steers were euthanatized and necropsied; livers were examined, and protection was assessed. Anti-leukotoxin antibody titers in the control steers generally did not differ from the baseline (week 0) titers. The titers in the vaccinated groups increased, more so after the second injection, and the increase was generally dose dependent. At necropsy, all steers in the control group had liver abscesses. In the vaccinated groups, two out of five steers in the 1.0 ml group and one each in the 2.0, 5.0, and 2.25 ml (concentrated) groups had liver abscesses. The difference suggests a protective effect of antileukotoxin antibodies against experimentally induced liver abscesses

An immunochromatographic serological assay for the diagnosis of Mycobacterium tuberculosis

10.1016/S0147-9571(01)00016-9Comparative Immunology, Microbiology and Infectious Diseases25121-27CIMI