Abstract
Hospital wastewater (HWW) is increasingly recognized as a critical
environmental and public health concern due to its complex composition, which
includes pathogenic microorganisms, antibiotic-resistant bacteria, pharmaceutical
residues, and high organic and nutrient loads. The present study was conducted to
assess the occurrence and diversity of pathogenic microorganisms, evaluate
antimicrobial resistance patterns, and examine key physicochemical characteristics
of hospital wastewater in Erbil City, Kurdistan Region–Iraq, with an emphasis on
potential environmental and public health impacts.
Wastewater samples were collected monthly from three major hospitals in
Erbil City (Hawler Teaching Hospital, Rizgary Teaching Hospital, and Rozhawa
Emergency Hospital) during a three-month period, from December 2024 to
February 2025, with three sampling events conducted for each hospital. Standard
methods recommended by the American Public Health Association (APHA) were
used for all microbiological and physicochemical analyses. Total coliforms and fecal
coliforms were enumerated using the Most Probable Number (MPN) method,
while fungal counts were determined using the pour plate technique. The VITEK 2
automated system was used for microbial identification and antibiotic
susceptibility testing. Molecular identification of selected bacterial isolates was
performed using partial 16S rRNA gene sequencing. Physicochemical parameters,
including temperature, pH, electrical conductivity (EC), biochemical oxygen
demand (BOD₅), nitrate (NO₃⁻), and phosphate (PO₄⁻³), were measured using
standard laboratory procedures.
The microbiological results showed extremely high counts of total and fecal
coliforms in all hospital wastewater samples. Total coliform levels reached up to
806.7×104 CFU/100 mL and fecal coliforms up to 296.7×104 CFU/100 mL. A total of
16 bacterial isolates were recovered from the three hospitals and identified by the
VITEK2 system. The isolates belonged mainly to families Enterobacteriaceae,
Aeromonadaceae, and Staphylococcaceae. The identified species included
Escherichia coli, E. coli O157:H7, Klebsiella pneumoniae, Proteus mirabilis,
Salmonella
enterica,
Serratia marcescens,
Aeromonas hydrophila/
punctata(caviae), Aeromonas sobria, Aeromonas caviae, and several
Staphylococcus species (S. aureus, S. sciuri, S. xylosus, S. lentus, and S. kloosii).
Molecular analysis using partial 16S rRNA gene sequencing confirmed the identity
of selected bacterial isolates, showing ≥99% similarity with NCBI GenBank
reference sequences.
Antimicrobial susceptibility testing showed a high prevalence of antibiotic
resistance among the isolated bacteria. Several isolates exhibited resistance to
commonly used antibiotics, particularly β-lactam antibiotics. Escherichia coli
isolates showed high resistance to cefuroxime and trimethoprimsulfamethoxazole, while Klebsiella pneumoniae and Proteus mirabilis
demonstrated strong resistance to multiple antibiotics. Staphylococcus aureus
isolates displayed variable resistance patterns, including methicillin resistance. The
presence of multidrug-resistant bacteria highlights the role of hospital wastewater
as an important environmental reservoir for antimicrobial resistance.
The study also identified several opportunistic fungal species in hospital
effluents, including Aspergillus niger, A. flavus, A. fumigatus, Penicillium spp.,
