Effects of natural sunlight on antimicrobial-resistant bacteria (AMRB) and antimicrobial-susceptible bacteria (AMSB) in wastewater and river water

Author(s):  
Takashi Azuma ◽  
Tetsuya Hayashi
2001 ◽  
Vol 43 (2) ◽  
pp. 91-99 ◽  
Author(s):  
T. Iwane ◽  
T. Urase ◽  
K. Yamamoto

Escherichia coli and coliform group bacteria resistant to seven antibiotics were investigated in the Tama River, a typical urbanized river in Tokyo, Japan, and at a wastewater treatment plant located on the river. The percentages of antibiotic resistance in the wastewater effluent were, in most cases, higher than the percentages in the river water, which were observed increasing downstream. Since the possible increase in the percentages in the river was associated with treated wastewater discharges, it was concluded that the river, which is contaminated by treated wastewater with many kinds of pollutants, is also contaminated with antibiotic resistant coliform group bacteria and E.coli. The percentages of resistant bacteria in the wastewater treatment plant were mostly observed decreasing during the treatment process. It was also demonstrated that the percentages of resistance in raw sewage are significantly higher than those in the river water and that the wastewater treatment process investigated in this study works against most of resistant bacteria in sewage.


2020 ◽  
Vol 2 (1) ◽  
pp. 59

The determination of antibiotic-resistant bacteria in Klang river water in Klang valley is performed as the river exposed to various environments. The analysis is performed through enumeration, isolation, and identification process. The water samples were obtained from the origin of the river, housing region, and hospital region. The coliforms obtained through enumeration and identification was then used to determine antibiotic sensitivity, minimum inhibitory concentration (MIC), and minimal bactericidal concentration (MBC). The level of coliforms was indicated through the most probable number (MPN), which 70 MPN per 100 ml of river water in the origin of the river while housing and hospital regions showed more than 1600 MPN per 100 ml of river water. The results obtained from the antibiotic sensitivity test showed that the degree of resistance of coliforms is varied in different regions. The zone of inhibition to ampicillin and tetracyclin for coliforms in housing regions is 20 mm, while the coliforms in the hospital region are 6 mm and 7 mm, respectively. The overall results showed that the level of coliforms and the antibiotic sensitivity of coliforms are different in various regions. The coliforms in the hospital region are more resistant to antibiotics compared to the housing region.


Biomolecules ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 941
Author(s):  
Van Khanh Nguyen ◽  
Myung-Gyu Ha ◽  
Ho Young Kang ◽  
Dinh Duc Nguyen

Manganese-oxidizing bacteria have been widely investigated for bioremediation of Mn-contaminated water sources and for production of biogenic Mn oxides that have extensive applications in environmental remediation. In this study, a total of 5 Mn-resistant bacteria were isolated from river water and investigated for Mn removal. Among them, Ochrobactrum sp. NDMn-6 exhibited the highest Mn removal efficiency (99.1%). The final precipitates produced by this strain were defined as a mixture of Mn2O3, MnO2, and MnCO3. Optimal Mn-removal performance by strain NDMn-6 was obtained at a temperature range of 25–30 °C and the salinity of 0.1–0.5%. More interestingly, strain NDMn-6 could be resistant to salinities of up to 5%, revealing that this strain could be possibly applied for Mn remediation of high salinity regions or industrial saline wastewaters. This study also revealed the potential of self-detoxification mechanisms, wherein river water contaminated with Mn could be cleaned by indigenous bacteria through an appropriate biostimulation scheme.


2019 ◽  
Vol 100 ◽  
pp. 00061 ◽  
Author(s):  
Adriana Osińska ◽  
Ewa Korzeniewska ◽  
Monika Harnisz ◽  
Sebastian Niestępski ◽  
Piotr Jachimowicz

Wastewater treatment plants (WWTPs) are major reservoirs of antibiotic-resistant bacteria (ARB) which are transported to the natural environment with discharged effluents. Samples of untreated wastewater (UWW) and treated wastewater (TWW) from four municipal WWTPs and samples of river water collected upstream (URW) and downstream (DRW) from the effluent discharge point were analyzed in the study. The total counts of bacteria resistant to β-lactams and tetracyclines and the counts of antibiotic-resistant Escherichia coli were determined. Antibiotic-resistant bacteria, including antibiotic-resistant E. coli, were removed with up to 99.9% efficiency in the evaluated WWTPs. Despite the above, ARB counts in TWW samples were high at up to 1.25x105 CFU/mL in winter and 1.25x103 CFU/mL in summer. Antibiotic-resistant bacteria were also abundant (up to 103 CFU/ml) in URW and DRW samples collected in winter and summer. In both UWW and TWW samples, the counts of ARB and antibiotic-resistant E. coli were at least one order of magnitude lower in summer than in winter. The study revealed that despite the high efficiency of bacterial removal in the wastewater treatment processes, considerable amounts of ARB are released into the environment with TWW and that the percentage of ARB in total bacterial counts increases after wastewater treatment.


2007 ◽  
Vol 73 (17) ◽  
pp. 5421-5425 ◽  
Author(s):  
Jeannette Muñoz-Aguayo ◽  
Kevin S. Lang ◽  
Timothy M. LaPara ◽  
Gerardo González ◽  
Randall S. Singer

ABSTRACT Antibiotics and antibiotic metabolites have been found in the environment, but the biological activities of these compounds are uncertain, especially given the low levels that are typically detected in the environment. The objective of this study was to estimate the selection potential of chlortetracycline (CTC) on the antibiotic resistance of aerobic bacterial populations in a simulated river water ecosystem. Six replicates of a 10-day experiment using river water in continuous flow chemostat systems were conducted. Each replicate used three chemostats, one serving as a control to which no antibiotic was added and the other two receiving low and high doses of CTC (8 μg/liter and 800 μg/liter, respectively). The addition of CTC to the chemostats did not impact the overall level of cultivable aerobic bacteria (P = 0.51). The high-CTC chemostat had significantly higher tetracycline-resistant bacterial colony counts than both the low-CTC and the control chemostats (P < 0.035). The differences in resistance between the low-CTC and control chemostats were highly nonsignificant (P = 0.779). In general a greater diversity of tet resistance genes was detected in the high-CTC chemostat and with a greater frequency than in the low-CTC and control chemostats. Low levels of CTC in this in vitro experiment did not select for increased levels of tetracycline resistance among cultivable aerobic bacteria. This finding should not be equated with the absence of environmental risk, however. Low concentrations of antibiotics in the environment may select for resistant bacterial populations once they are concentrated in sediments or other locations.


2016 ◽  
Vol 83 (5) ◽  
Author(s):  
Ryota Gomi ◽  
Tomonari Matsuda ◽  
Yasufumi Matsumura ◽  
Masaki Yamamoto ◽  
Michio Tanaka ◽  
...  

ABSTRACT Contamination of surface waters by antimicrobial-resistant bacteria and pathogenic bacteria is a great concern. In this study, 531 Escherichia coli isolates obtained from the Yamato River in Japan were evaluated phenotypically for resistance to 25 antimicrobials. Seventy-six isolates (14.3%) were multidrug resistant (MDR), 66 (12.4%) were nonsusceptible to one or two classes of agents, and 389 (73.3%) were susceptible. We performed whole-genome sequencing of selected strains by using Illumina technology. In total, the genome sequences of 155 strains were analyzed for antibiotic resistance determinants and phylogenetic characteristics. More than 50 different resistance determinants, including acquired resistance genes and chromosomal resistance mutations, were detected. Among the sequenced MDR strains (n = 66), sequence type 155 (ST155) complex (n = 9), ST10 complex (n = 9), and ST69 complex (n = 7) were prevalent. Among extraintestinal pathogenic E. coli (ExPEC) strains (n = 58), clinically important clonal groups, namely, ST95 complex (n = 18), ST127 complex (n = 8), ST12 complex (n = 6), ST14 complex (n = 6), and ST131 complex (n = 6), were prevalent, demonstrating the clonal distribution of environmental ExPEC strains. Typing of the fimH (type 1 fimbrial adhesin) gene revealed that ST131 complex strains carried fimH22 or fimH41, and no strains belonging to the fimH30 subgroup were detected. Fine-scale phylogenetic analysis and virulence gene content analysis of strains belonging to the ST95 complex (one of the major clonal ExPEC groups causing community-onset infections) revealed no significant differences between environmental and clinical strains. The results indicate contamination of surface waters by E. coli strains belonging to clinically important clonal groups. IMPORTANCE The prevalence of antimicrobial-resistant and pathogenic E. coli strains in surface waters is a concern because surface waters are used as sources for drinking water, irrigation, and recreational purposes. In this study, MDR and ExPEC strains in river water were characterized by genomic sequencing and analysis. We detected more than 50 resistance determinants and identified clonal groups specific to MDR and ExPEC strains. This study showed contamination of surface waters by E. coli strains belonging to clinically important clonal groups. Overall, this study advances our understanding of environmental MDR and ExPEC strains.


2012 ◽  
Vol 119-120 ◽  
pp. 32-39 ◽  
Author(s):  
Michela Sturini ◽  
Andrea Speltini ◽  
Federica Maraschi ◽  
Antonella Profumo ◽  
Luca Pretali ◽  
...  

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