Efficacy evaluation of commercial disinfectants by using Salmonella enterica serovar Typhimurium as a test organism

The efficacies of six commercial disinfectants were evaluated by using Salmonella enterica serovar Typhimurium under simulated natural conditions such as sub-zero temperature, short disinfecting time, and surface type (uneven or smooth). We used a suspensionmodel test to determine the disinfecting efficacy under varying contact times (1, 5, 10, and 30 min) and temperatures (25℃, 4℃, 0℃, and −10℃). The bactericidal effect according to surface structure was measured by using a carriermodel test at 25℃ and −10℃. The effective concentrations of each disinfectant were fixed to give a disinfecting effect within a short time (< 1 min) at 25℃ and −10℃. The suspension model results revealed that bactericidal efficacy significantly dropped at low temperature for most of the disinfectants used; a sodium dichloroisocyanurate product showed the strongest efficacy. In the carrier test, bacterial load on a wooden surface was more difficult to remove than that on a stainless-steel surface. The results show that commercial disinfectant products vary in their disinfecting efficacy, which is affected by several field factors including temperature, contact time, and carrier material. Environmental conditions and surface type for disinfection should be considered prior to selecting an optimal disinfectant in the field.

Prevalence and antimicrobial resistance of Salmonella spp. and Escherichia coli isolated from ducks in Korea

This study was conducted to investigate the prevalence and antimicrobial resistance of Salmonella spp. and Escherichia (E.) coli isolated from ducks in Korea. A total of 400 cecal content samples were collected from 40 duck farms in Korea. Isolated Salmonella spp. and E. coli strains were 83 and 364 of the 400 cecal samples, respectively. The most prevalent serotype among the 83 Salmonella isolates was Salmonella Typhimurium (51 isolates: 61.45%). Resistance to the tested antimicrobial agents by Salmonella isolates was low except for erythromycin, while the resistance of the E. coli isolates to the other tested antimicrobial agents was high and 90.9% (331/364) of E. coli isolates showed multiantimicrobial resistance. Antimicrobial resistance in duck zoonotic pathogens should be of concern to the Korean duck industry, as these pathogens exhibit a high rate of antimicrobial resistance and pose a potential hazard to public health.

Contamination status of groundwater used as livestock drinking in beef and dairy cattle farms, Korea / 대한수의학회지

In Korea, groundwater is main water source in livestock farms. Most dairy and cattle farms have constructed their own wells for human drinking and livestock farming. However, these private residential wells have not been controlled by government and also there was scant study about livestock drinking water quality. Therefore this study was to monitor of the livestock farms' groundwater quality in Korea. Water samples were collected at 123 dairy and cattle farms and were analysed forty six substances with quality standard for drinking water approved by the Minister of Environment. Seventy eight (63.4%) of 123 samples failed to drinking water stand a test. The most frequent contaminants were nitrate-nitrogen and microbial. 22.8% (n = 28) of samples showed nitrate-N concentration of higher than 10 mg/L meant that can't be used drinking water for human and the Nitrate-N concentration analysed in the range of 0.2 to 61.2 mg/L. All of 78 failed to drinking samples had microbial problems, especially 5.7% (n = 7) of samples indicated water could be contaminated by feces. Other contaminants detected were zinc and evaporation residue. Especially detected zinc concentration (32 mg/L) was about ten times higher than standard of zinc (3 mg/L). Regression analysis indicated that groundwater pH did not influence to nitrate-N concentration but the hardness and chloride could affect to nitrate-N concentration in the groundwater. Most livestock farms were adjacent to crop farmland in Korea. This could cause contamination of groundwater with nitrate-N and pesticide that could accumulate livestock product. Moreover Heavy metal such as zinc and copper could be released from a corrosive plated water pipe in livestock farm. Put together, Korea livestock system is indoor, not pasture-based, hence livestock could be exposed to potential contaminated water consistently. Therefore on the basis of these data, appropriate livestock drinking water quality standards should be prepared to keep livestock healthy and their product safe. Further, livestock drinking water quality should be monitored continuously in suitable livestock drinking water standards.