University of Tehran Press Iranian Journal of Soil and Water Research 2008-479X 52 8 2021 10 23 Investigation of Antibiotic Resistant Coliform Bacteria in Zarjoub River Investigation of Antibiotic Resistant Coliform Bacteria in Zarjoub River 2061 2076 84854 10.22059/ijswr.2021.322755.668946 FA Mohammad Bagher Farhangi Soil Science Department, Faculty of agricultural Science, University of Guilan, Rasht, Iran Rasht, P.O. Box 41635-1314, Iran. Nasrin Ghorbanzadeh Soil Science Department, Faculty of agricultural Science, University of Guilan, Rasht, Iran. Milad Amini Soil Science Department, Faculty of agricultural Science, University of Guilan, Rasht, Iran. Shahrokh Ghovvati Animal Science Department, Faculty of agricultural Science, University of Guilan, Rasht, Iran. Journal Article 2021 04 26 Contamination of rivers to antibiotic-resistant bacteria causes these bacteria to spread in the environment and enter the food chain, which is a serious threat to public health. The aim of this study was to investigate the presence of antibiotic resistant coliforms in the Zarjoub River. To explore the source of contamination, water sampling was carried out in three points along the river course; entry, middle and exit of Rasht city, in August 2017 and February 2018. Plate count method was adopted to enumerate coliform bacteria number in Eosin-Methylene Blue agar medium with 100 µg mL-1 of cephalexin, gentamicin, doxycycline and ciprofloxacin antibiotics. Antibiotic resistance of Escherichia coli, as an indicator bacterium, was tested based on Kirby-Bauer method and Zone of Inhibition was measured (ZOI). The mean highest number of antibiotic-resistant coliforms was against ciprofloxacin in August samples (6.66 Log CFU mL-1) and the lowest mean number of those was against gentamicin in February samples (3.44 Log CFU mL-1). Also, the highest number of antibiotic-resistant coliforms was obtained at the sampling point in the middle of the city in August. The trend of antibiotic-resistant coliforms showed that while their number increased as the river passed through the city in February, it was more than two other sampling points in the middle of the city in August. E. coli resistance pattern, based on the ZOI, showed that this bacterium was resistant to all tested antibiotics except doxycycline in all three sampling points and also was resistant to cephalexin in both months of sampling. Overall, 35% of culturable coliforms of Zarjoub River were resistant to ciprofloxacin, and E. coli strains isolated from the river water (three sampling points and two months) were resistant to cephalexin. Therefore, downstream use of Zarjoub River water is not suitable for agriculture and aquaculture, especially in the warm season. Contamination of rivers to antibiotic-resistant bacteria causes these bacteria to spread in the environment and enter the food chain, which is a serious threat to public health. The aim of this study was to investigate the presence of antibiotic resistant coliforms in the Zarjoub River. To explore the source of contamination, water sampling was carried out in three points along the river course; entry, middle and exit of Rasht city, in August 2017 and February 2018. Plate count method was adopted to enumerate coliform bacteria number in Eosin-Methylene Blue agar medium with 100 µg mL-1 of cephalexin, gentamicin, doxycycline and ciprofloxacin antibiotics. Antibiotic resistance of Escherichia coli, as an indicator bacterium, was tested based on Kirby-Bauer method and Zone of Inhibition was measured (ZOI). The mean highest number of antibiotic-resistant coliforms was against ciprofloxacin in August samples (6.66 Log CFU mL-1) and the lowest mean number of those was against gentamicin in February samples (3.44 Log CFU mL-1). Also, the highest number of antibiotic-resistant coliforms was obtained at the sampling point in the middle of the city in August. The trend of antibiotic-resistant coliforms showed that while their number increased as the river passed through the city in February, it was more than two other sampling points in the middle of the city in August. E. coli resistance pattern, based on the ZOI, showed that this bacterium was resistant to all tested antibiotics except doxycycline in all three sampling points and also was resistant to cephalexin in both months of sampling. Overall, 35% of culturable coliforms of Zarjoub River were resistant to ciprofloxacin, and E. coli strains isolated from the river water (three sampling points and two months) were resistant to cephalexin. Therefore, downstream use of Zarjoub River water is not suitable for agriculture and aquaculture, especially in the warm season.

https://ijswr.ut.ac.ir/article_84854_2ed6a22152c391840ee85ccee8b44f31.pdf