*Article* **Antibiotic Resistance and Antibiotic Resistance Genes in** *Escherichia coli* **Isolates from Hospital Wastewater in Vietnam**

**La Thi Quynh Lien 1,2,\* , Pham Thi Lan 3, Nguyen Thi Kim Chuc 3, Nguyen Quynh Hoa 4, Pham Hong Nhung 3,5, Nguyen Thi Minh Thoa 3, Vishal Diwan 1,6, Ashok J. Tamhankar 1,7 and Cecilia Stålsby Lundborg <sup>1</sup>**


Received: 24 April 2017; Accepted: 23 June 2017; Published: 29 June 2017

**Abstract:** The environmental spread of antibiotic-resistant bacteria has been recognised as a growing public health threat for which hospitals play a significant role. The aims of this study were to investigate the prevalence of antibiotic resistance and antibiotic resistance genes (ARGs) in *Escherichia coli* isolates from hospital wastewater in Vietnam. Wastewater samples before and after treatment were collected using continuous sampling every month over a year. Standard disk diffusion and E-test were used for antibiotic susceptibility testing. Extended-spectrum beta-lactamase (ESBL) production was tested using combined disk diffusion. ARGs were detected by polymerase chain reactions. Resistance to at least one antibiotic was detected in 83% of isolates; multidrug resistance was found in 32%. The highest resistance prevalence was found for co-trimoxazole (70%) and the lowest for imipenem (1%). Forty-three percent of isolates were ESBL-producing, with the *blaTEM* gene being more common than *blaCTX-M.* Co-harbouring of the *blaCTX-M*, *blaTEM* and *qepA* genes was found in 46% of isolates resistant to ciprofloxacin. The large presence of antibiotic-resistant *E. coli* isolates combined with ARGs in hospital wastewater, even post-treatment, poses a threat to public health. It highlights the need to develop effective processes for hospital wastewater treatment plants to eliminate antibiotic resistant bacteria and ARGs.

**Keywords:** antibiotic resistance; antibiotic resistance genes; *blaCTX-M*; *blaTEM*; *qepA*; hospital wastewater
