Characterization of multidrug resistant Salmonella recovered from diseased animals

Three hundred and eighty Salmonella isolates recovered from animal diagnostic samples obtained from four state veterinary diagnostic laboratories (AZ, NC, MO, and TN) between 2002 and 2003 were tested for antimicrobial susceptibilities and further characterized for bla(CMY) beta-lactamase genes, class 1 integrons and genetic relatedness using PFGE. Forty-seven serovars were identified, the most common being S. Typhimurium (26%), S. Heidelberg (9%), S, Dublin (8%), S. Newport (8%), S. Derby (7%), and S. Choleraesuis (7%). Three hundred and thirteen (82%) isolates were resistant to at least one antimicrobial, and 265 (70%) to three or more antimicrobials. Resistance was most often observed to tetracycline (78%), followed by streptomycin (73%), sulfamethoxazole (68%), and ampicillin (54%), and to a lesser extent chloramphenicol (37%), kanamycin (37%), amoxicillin-clavulanic acid (20%), and ceftiofur (17%). With regards to animal of origin, swine Salmonella isolates displayed the highest rate of resistance, being resistant to at least one antimicrobial (92%), followed by those recovered from turkey (91%), cattle (77%), chicken (68%), and equine (20%). Serovars commonly showing multidrug resistance (MDR) to > or =9 antimicrobials were S. Uganda (100%), S. Agona (79%), and S. Newport (62%), compared to S. Heidelberg (11%) and S. Typhimurium (7%). Class-1 integrons were detected in 43% of all isolates, and were found to contain aadA, aadB, dhfr, cmlA and sat1 gene cassettes alone or in various combinations. All ceftiofur resistant isolates (n=66) carried the bla(CMY) beta-lactamase gene. A total of 230 PFGE patterns were generated among the 380 isolates tested using XbaI, indicating extensive genetic diversity across recovered Salmonella serovars, however, several MDR clones were repeatedly recovered from different diseased animals.     

Determination of oil,emulsifier and polymer or salt content of spray adjuvants

A method for the separation of the oil, emulsifier and polymer or salt fractions of adjuvants is described. The adjuvant is dissolved in 90% aqueous ethanol and filtered to remove polymers or salt. Light petroleum (distillation range 30–40°C) is added to the solution in a separating funnel. The light petroleum fraction is subsequently extracted with successive aliquots of 80, 70, 60 and 50% aqueous ethanol. The whole of the ethanol and light petroleum fractions are evaporated to dryness to yield the emulsifier and oil fractions respectively. Emulsifier, oil and polymer or salt are determined gravimetrically. The method successfully detected the presence of polymer or salt in adjuvants, but could not distinguish between them when both were present in the same product. The adjuvants could be classified into four broad classes; those containing > 70% emulsifier (wetter-spreaders), those containing > 75% oil (anti-evaporants), those containing a high proportion of polymer (film-forming substances), and those containing comparable amounts of all three components (multi-purpose adjuvants).     

Some aspects of crop variation in ‘Golden Delicious’ apple trees

Fruit-set of ‘Golden Delicious’ apple trees was found to be largely independent of seasonal differences and much more closely related to the initial number of blossom clusters, when compared with many other apple cultivars under English conditions. In one young orchard, yield became increasingly a function of trunk girth during the first 3 cropping-years, but the trees then abruptly developed a biennial rhythm. Thereafter, blossom production was negatively correlated with the number of clusters in the previous year rather than with the number of fruits.Applications of daminozide or GA₃ appeared to increase or decrease, respectively, the amount of return bloom without altering the negative correlation with the number of clusters in the previous year. Chemical fruit-thinning with a mixture of carbaryl and NAA also appeared to be effective in increasing return bloom.     

The effect of dietary protein on the pathogenesis of acute ovine haemonchosis

Two experiments were conducted to examine the ifluence of dietary proteins on parasite establishment and pathogenesis in Finn Dorset/Dorset Horn lambs infected with Haemonchus contortus. The lambs were introduced to high (169 g) or low (88 g crude protein (CP) kg⁻¹ dry matter (DM)) protein diets at 3 months of age and infected 1 month later with 350 larvae kg⁻¹ body weight (BW). Blood and faecal smaples were collected for analysis and body weights recorded weekly. In the first experiments some of the infected lambs were killed 6 weeks after infection and the remainder 5 weeks later. In the second experimental all the infected lambs were killed 4 weeks after infection.

The results showed that lambs on a low protein diet were less able to withstand the pathogenic effects of infection with 350 H. contortus larvae kg⁻¹ BW than lambs given the higher protein diet. Thus mortality was greater in the low protein group and adverse clinical signs, such as inappetance, weight loss and oedema were osbserved more frequently. This group also had a more severe anaemia, hypoproteinaemia and hypoalbuminnaemia than the high protein group. In contrast, faecal egg counts, total daily faecal egg output and worm burdens were similar in all groups of infected lambs, indicating that the diets did not influence parasite establishment.     

Efficacy of avermectin B1 given orally against equine intestinal strongyles and Onchocera microfilaria

Three groups of horses and ponies (N = 13, 13 and 12) were treated with ivermectin paste (0.2 mg/kg p.o.), avermectin B1 solution (0.2 mg/kg p.o.), or fenbendazole suspension (10 mg/kg via nasogastric tube). The avermectin B1 was a 1% solution in a propylene glycolglycerol formal base. Faecal strongyle egg counts were performed before, and 14, 28, 42, 56 and 70 d, after treatment. Full-thickness skin biopsies from the neck, pectoral and umbilical regions were examined for Onchocera microfilaria before treatment, and again 14 and 70 d later. Ivermectin therapy produced a significant (P less than 0.01) decrease in mean strongyle egg counts 14, 28, 42 and 56 d after treatment. Avermectin B1 therapy resulted in significant (P less than 0.01) decreases in mean strongyle egg counts 14, 28 and 42 d after treatment. All horses given ivermectin or avermectin B1 had zero strongyle egg counts 14 and 28 d after treatment. Fenbendazole failed to significantly decrease strongyle egg counts. Both ivermectin and avermectin B1 resulted in zero microfilaria counts in all horses 14 d after treatment. On day 70 the percentage decrease in microfilaria counts were 100% and 99.6% respectively. Fenbendazole failed to significantly decrease microfilaria counts. The oral administration of this formulation of avermectin B1 appeared to be highly efficacious against intestinal strongyles and Onchocera microfilaria. The duration of anti-strongyle activity was, however, significantly (P less than 0.01) shorter than that of ivermectin paste.