A novel series of milbemycin antibiotics from Streptomyces strain E225. I. Discovery, fermentation and anthelmintic activity.

A novel series of milbemycin antibiotics were produced by soil isolate, strain E225 which was shown to be a Streptomyces species. The antibiotics displayed anthelmintic activity against Trichostrongylus colubriformis in the gerbil. Two of the compounds, VM 44857 and VM 44866 were shown to be potent anthelmintics against mixed nematode infections in sheep.

Reproducible pneumonia in gnotobiotic piglets induced with broth cultures of Mycoplasma hyopneumoniae and the effect of animal passage on virulence.

The virulence of a laboratory adapted culture of Mycoplasma hyopneumoniae strain NB12 was determined in three- to five-day-old gnotobiotic piglets. Intranasal inoculation or exposure to an aerosol of the culture caused low incidences of pneumonia in the piglets. Passage of M hyopneumoniae strain NB12 in gnotobiotic piglets resulted in a rapid increase in virulence. After only three in vivo passages, severe pneumonia involving most lobes of the lung developed in all inoculated piglets within three and a half weeks. All 49 piglets inoculated with the piglet-passaged NB12 strain in nine subsequent experiments developed pneumonia but the extent of the pneumonic lesions varied considerably from piglet to piglet. The histopathology of the lung lesions was similar to that reported as being induced by other strains of M hyopneumoniae in gnotobiotic piglets and resembled that seen previously in conventionally reared neonatal piglets inoculated with homogenised lung from pigs with enzootic pneumonia. Aspiration pneumonia caused by milk inhalation occurred in some piglets. The pneumonia induced with the piglet-passaged NB12 strain was judged to be suitable for the study of porcine enzootic pneumonia or for the evaluation of chemotherapeutic agents.

Tylosin tartrate and tiamutilin effects on experimental piglet pneumonia induced with pneumonic pig lung homogenate containing mycoplasmas, bacteria and viruses.

The effects of tylosin tartrate and tiamutilin were examined in pneumonias induced experimentally in neonatal piglets with a homogenate of pneumonic pig lung, obtained from pigs with naturally acquired enzootic pneumonia. The homogenate contained mycoplasmas, including Mycoplasma hyopneumoniae (M suipneumoniae) and M hyorhinis, and certain bacteria and viruses. The experimental pneumonias generally resembled mycoplasmal pneumonia histologically but were complicated by aspiration pneumonia in some animals. both tylosin tartrate (50 mg/kg) and tiamutilin (10 mg/kg) administered orally twice daily for 10 days, beginning 14 days after intranasal infection, significantly reduced the incidence and severity of macroscopical pneumonic lung lesions. M hyopneumoniae could be isolated from the lungs of the unmedicated piglets, but not from drug-treated piglets. The numbers of M hyorhinis, Acholeplasma granularum, Haemophilus parasuis, Pasteurella multocida and P haemolytica in the lung tissue of the infected piglets were significantly reduced by drug therapy. The role of bacterial in the experimental infection appeared to be that of secondary invaders.

The intracellular reserve polysaccharide of Clostridium pasteurianum.

An amylopectinlike polysaccharide (granulose) was the only glucan produced in significant quantities by six wild-type strains of Clostridium pasteurianum grown in glucose minimal medium. The intracellular polysaccharide granules laid down before sporulation contained only this amylopectin. No intracellular dextran was discovered in these wild-type strains, nor in a granulose-negative mutant strain of C. pasteurianum possessing an ADP glucose pyrophosphorylase (EC2.7.7.27) but lacking a granulose synthase (i.e. ADP glucose-alpha-1,4-glucan glucosyl transferase, EC2.4.1.21). Furthermore, methylation analysis demonstrated that (1 leads to 6) linked alpha-D-glucose units accounted for less than 2% of the entire glucose content of these organisms.