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Antibiotics are an important group of
pharmaceuticals used extensively in health
care for the treatment and prevention of
microbial infections. Antibiotic resistance
has become a major health concern; thus, there
is a growing interest in exploring the
occurrence of antibiotic resistant bacteria in
environment. Cloxacillin (CLOX), a broad
spectrum penicillin type antibiotic, is
commonly used for community acquired
pneumonia, superficial skin infections,
cellulitis etc. The present study focused on
quantification of CLOX and isolation of
cloxacillin-resistant (CLOX1) bacteria from
ten wastewater discharge drains in some
selected hospitals, Sri Lanka. Solid-Phase
Extraction (SPE) and High Performance
Liquid Chromatography (HPLC) were
employed to quantify CLOX. Isolation of
CLOXr bacteria was done by standard pour
plate method, after 14 days of enrichment.
Minimum Inhibitory Concentration (MIC) was
observed at 60- 720 ppm via 96-well plate
method and pour plate method.
Among selected locations the highest
concentration of CLOX was recorded as
8.815±0.002 ppm in Karapitiya hospital
effluent and contamination was ranged
between 8.815±0.002 ppm to 0 ppm. CLOXr
bacteria were identified (>360ppm MICs) as
Staphylococcus aureus, Escherichia coli,
Enterobacter ludwigii, Bacillus sp., Bacillus
cereus and Pseudomonas aeruginosa by 16S
rRNA sequencing. MIC values for each
bacterial strain were recorded as 540 ppm,
660 ppm, 600 ppm, 660 ppm, 660 ppm and
540 ppm respectively.
The antibiotic concentrations observed in most
effluent water samples have exceeded the
maximum permissible level (< 0.001 ppmwater) given by the World Health Organization
for aquatic environment. Thus, continuous
monitoring and further studies are needed to get
baseline information on contamination status
of antibiotics, in order to prepare guidelines
and strategic plan for the country to minimize
health issues related to antibiotic resistance.
