Reduced Bacterial Counts from a Sewage Treatment Plant but Increased Counts and Antibiotic Resistance in the Recipient Stream in Accra, Ghana—A Cross-Sectional Study
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Date
2021
Journal Title
Journal ISSN
Volume Title
Publisher
MDPI
Abstract
Wastewater treatment plants receive sewage containing high concentrations of bacte ria and antibiotics. We assessed bacterial counts and their antibiotic resistance patterns in water
from (a) influents and effluents of the Legon sewage treatment plant (STP) in Accra, Ghana and
(b) upstream, outfall, and downstream in the recipient Onyasia stream. We conducted a cross sectional study of quality-controlled water testing (January–June 2018). In STP effluents, mean
bacterial counts (colony-forming units/100 mL) had reduced E. coli (99.9% reduction; 102,266,667 to
710), A. hydrophila (98.8%; 376,333 to 9603), and P. aeruginosa (99.5%; 5,666,667 to 1550). Antibiotic
resistance was significantly reduced for tetracycline, ciprofloxacin, cefuroxime, and ceftazidime
and increased for gentamicin, amoxicillin/clavulanate, and imipenem. The highest levels were
for amoxicillin/clavulanate (50–97%) and aztreonam (33%). Bacterial counts increased by 98.8%
downstream compared to the sewage outfall and were predominated by E. coli, implying intense
fecal contamination from other sources. There was a progressive increase in antibiotic resistance
from upstream, to outfall, to downstream. The highest resistance was for amoxicillin/clavulanate
(80–83%), cefuroxime (47–73%), aztreonam (53%), and ciprofloxacin (40%). The STP is efficient in
reducing bacterial counts and thus reducing environmental contamination. The recipient stream is
contaminated with antibiotic-resistant bacteria listed as critically important for human use, which
needs addressing.
Description
Research Article
Keywords
SORT IT, One Health, operational research, sustainable development goals, antimicrobial resistance, antibiotic residues, wastewater treatment