Antimicrobial Resistance of Staphylococcus aureus Isolated from Hospital Wastewater in Kermanshah, Iran
Received 5 May 2020
Accepted for publication 8 July 2020
Published 5 August 2020 Volume 2020:13 Pages 1035—1042
Checked for plagiarism Yes
Review by Single-blind
Peer reviewer comments 3
Editor who approved publication: Professor Marco Carotenuto
Alisha Akya,1,2 Roya Chegenelorestani,1 Jila Shahvaisi-Zadeh,3 Arezoo Bozorgomid1
1Infectious Diseases Research Center, Health Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran; 2Department of Microbiology, Kermanshah University of Medical Sciences, Kermanshah, Iran; 3Clinical Research Development Center, Imam Reza Hospital, Kermanshah University of Medical Sciences, Kermanshah, Iran
Correspondence: Arezoo Bozorgomid Infectious Diseases Research Center
Imam Reza Hospital, Daneshgah St., Shahid Shiroodi Blvd., Kermanshah 6715847141, Iran
Tel +98-918 872 8269
Introduction: Hospital wastewater contains highly resistant and virulent bacteria that can spread into the environment. This study was conducted to investigate the antimicrobial resistance of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) in raw and treated hospital wastewater.
Methods: During a three-month period, 40 sewage samples were collected from the hospital sewage (Kermanshah, Iran), and S. aureus were identified using culture and biochemical tests. MRSA was detected by resistance to cefoxitin. Antibiotic resistance (AR) was determined using disk diffusion according to the Clinical and Laboratory Standards Institute (CLSI) in 20 MSSA (10 raw and 10 treated sewage) and 40 MRSA isolates (20 raw and 20 treated sewage). The antimicrobial resistance genes (ARGs) were determined by PCR.
Results: Eleven and eight percent of the isolates were MRSA in raw and treated sewage samples, respectively. Out of 60 isolates, 59 (98%) were multidrug resistant (MDR). The most common ARGs were mecA (raw=100%, treated=100%), aacA-D (raw=100%, treated=85%) and tetK (raw =95%, treated =45%) in MRSA, while the tetM gene was the most abundant gene (raw=50%, treated=80%) in MSSA. None of isolates (n=60) was positive for the vanB gene. MSSR (n=20) had the highest level of resistance against penicillin (100%), clindamycin (raw=90%, treated=90%), azithromycin (raw=80%, treated=90%). All MRSA isolates (n=40,100%) in both raw and treated sewage samples were non-susceptible to penicillin, oxacillin and azithromycin. There was no significant difference in the frequency AR and ARGs between raw and treated sewage samples (p> 0.05).
Conclusion: The results indicated a high frequency of MDR and ARGs in both raw and treated sewage isolates which could be released into the environment through sewage system and pose a serious threat to public health. Hospital wastewater treatment processes should be improved in order to prevent the dissemination of the most resistant strains of S. aureus.
Keywords: antibiotic resistance, antibiotic resistance genes, hospital wastewater, Staphylococcus aureus
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