Antimicrobial Resistance Pilot Surveillance of Pigs and Chickens in Vietnam, 2017-2019.

Antimicrobial use (AMU) and antimicrobial resistance (AMR) are a growing public health and economic threat in Vietnam. We conducted a pilot surveillance programme in five provinces of Vietnam, two in the south and three in the north, to identify antimicrobial resistance (AMR) in rectal swab samples from pigs and fecal samples from chickens at slaughter points during three different points in time from 2017 to 2019. Escherichia coli (E. coli) and non-typhoidal Salmonella (NTS) isolates were tested for antimicrobial susceptibility using disk diffusion assay for 19 antimicrobial agents belonging to nine antimicrobial classes and Etest for colistin (polymyxin). Almost all E. coli (99%; 1029/1042) and NTS (96%; 208/216) isolates were resistant to at least one antimicrobial agent; 94% (981/1042) of E. coli and 89% (193/216) of NTS isolates were multidrug-resistant (MDR). Higher proportions of E. coli and NTS isolated from chickens were resistant to all antimicrobial classes than those isolates from pigs. There was a significantly higher proportion of MDR NTS isolates from the southern provinces of Ho Chi Minh City and Long An (p = 0.008). Although there were increasing trends of NTS in proportion of resistance to fluoroquinolone over the three surveillance rounds, there was a significant decreasing trend of NTS in proportion of resistance to polymyxin (p = 0.002). It is important to establish an annual AMR surveillance program for livestock in Vietnam to assess the impact of interventions, observe trends and drive decision making that ultimately contributes to reducing AMR public health threat.

Heavy metals extraction from anaerobically digested sludge.

This paper reports on the chemical extraction efficiency in the removal of heavy metals from sludge from an activated-sludge system, which receives as influent both industrial and municipal wastewater. Utilizing a series of chemical extractants in a sequential order comprised the first phase of the research, called sequential chemical extraction (SCE). The work started with the well-known Tessier method followed by Veeken and by Sims and Kline SCE schemes. Afterwards, modified versions of Tessier and Veeken schemes were applied. The second phase, named chemical extraction using pH progressive changes, concerns an alternative to the extraction process. Four acids were tested: nitric, hydrochloric, oxalic and citric and the pH values as well as the time were varied. Some conclusions reveal that although modifying Tessier and Veeken schemes provides more consistent results, SCE is still an imperfect method regarding specificity and selectivity. Besides, it is not advisable to apply one SCE scheme developed for one specific situation to another one, once the accurateness of the method depends on several factors such as sort of material and chemicals, contact time, temperature, etc. The extraction efficiency increases using nitric or hydrochloric acids at low pH values, promoting high extraction efficiency level.