Sensitivity of Escherichia coli O157:H7 strain 932 to selected anticoccidial drugs in broiler chicks

Robenidine Analogues Are Potent Antimalarials in Drug-Resistant Plasmodium falciparum

Robenidine is a veterinary drug used in the poultry industry to treat coccidiosis caused by parasites in the Eimeria genus. Though this compound and related aminoguanidines have recently been studied in other pathogens, the chemotype has not been systematically explored to optimize antimalarial activity despite the close genetic relationship between Eimeria and Plasmodium (both are members of the Apicomplexa phylum of unicellular, spore-forming parasites). In this study, a series of aminoguanidine robenidine analogues was prepared and tested in vitro against Plasmodium falciparum, including multidrug-resistant strains. Selected compounds were further evaluated in vivo against murine Plasmodium yoelii in mice. Iterative structure–activity relationship studies led to the discovery of 1, an aminoguanidine with excellent activity against drug-resistant malaria in vitro and impressive in vivo efficacy with an ED₅₀ value of 0.25 mg/kg/day in a standard 4-day test.

The efficacy of TAMUS 2032 in preventing a natural outbreak of colibacillosis in broiler chickens in floor pens

A 42-d floor pen study was conducted with broiler chickens comparing the effects on bird performance of 12 ppm TAMUS 2032 (also known as BT) and 55 ppm bacitracin methylene disalicyclate (BMD) when fed alone or in combination with 99 ppm monensin (MON). Unmedicated and 99 ppm MON treatments were included in the study design. Beginning on d 22 of study, birds in all 6 treatments were subjected to a modulated house temperature and airflow to mimic conditions conducive to outbreaks of colibacillosis. A natural outbreak of colibacillosis developed beginning on d 27. Primary lesions in dead birds included airsacculitis and pericarditis with occasional findings of perihepatitis. At d 42 of study, means for weight gain in the TAMUS 2032 and TAMUS 2032 + MON treatments were greater in comparison with the unmedicated and BMD treatments, and means for feed conversion for both treatments were improved in comparison with the unmedicated treatment. Mean feed conversion in the TAMUS 2032 + MON treatment was also improved in comparison with BMD treatment. Mortality due to colibacillosis was reduced in the TAMUS 2032 (0.051%), TAMUS 2032 + MON (0.642%), and MON + BMD (1.515%) treatments in comparison with the unmedicated treatment (13.402%) and the BMD treatment (11.159%). The results of improved performance and reduced mortality indicated that 12 ppm TAMUS 2032 was highly efficacious against colibacillosis in growing chickens. The reduced mortality percentages in the MON + BMD treatment indicated that this combination also provided a good level of protection against the natural outbreak of colibacillosis.

Isolation of verotoxigenic Escherichia coli O157 from poultry

Results obtained by examination of cloacal swabs from poultry for the presence of verotoxigenic strains of E. coli O157:H7 are presented. Twenty samples (9.2%) of 216 samples examined were positive for E. coli O157. Out of 20 E. coli O157, 19 strains were positive for the production of both verotoxins (VT1 and VT2). However, none of them was positive for the presence of H7 antigen.