Occurrence and behavior of fluoroquinolone antibacterial agents (FQs) were investigated in
hospital wastewaters in Hanoi, Vietnam. Hospital wastewater in Hanoi is usually not treated and this
untreated wastewater is directly discharged into one of the wastewater channels of the city and eventually
reaches the ambient aquatic environment. The concentrations of the FQs, ciprofloxacin (CIP) and
norfloxacin (NOR) in six hospital wastewaters ranged from 1.1 to 44 and from 0.9 to 17 ?g l-1, respectively.
Total FQ loads to the city sewage system varied from 0.3 to 14 g d-1. Additionally, the mass flows of CIP
and NOR were investigated in the aqueous compartment in a small wastewater treatment facility of one
hospital. The results showed that the FQ removal from the wastewater stream was between 80 and 85%,
probably due to sorption on sewage sludge. Simultaneously, the numbers of Escherichia coli (E. coli) were
measured and their resistance against CIP and NOR was evaluated by determining the minimum inhibitory
concentration. Biological treatment lead to a 100-fold reduction in the number of E. coli but still more than a
thousand E. coli colonies per 100 ml of wastewater effluent reached the receiving water. The highest
resistance was found in E. coli strains of raw wastewater and the lowest in isolates of treated wastewater
effluent. Thus, wastewater treatment is an efficient barrier to decrease the residual FQ levels and the number
of resistant bacteria entering ambient waters. Due to the lack of municipal wastewater treatment plants, the
onsite treatment of hospital wastewater before discharging into municipal sewers should be considered as a
viable option and consequently implemented. ?? 2008 Elsevier Ltd. All rights reserved.
