Antimicrobial Susceptibility Profile of Common Species of Enterobacteriaceae in Wastewater Samples From Health Facilities, Abattoir and Downstream Rivers In Addis Ababa, Ethiopia

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Addis Ababa University


Spread of antimicrobial resistant bacteria and antimicrobial resistant genes is causing serious difficulties in the treatment of infection diseases worldwide. Monitoring of antimicrobial susceptibility profile of various bacterial pathogens in the health facilities and the environment is crucial for designing proper implementation of strategy to hamper spread of resistant pathogens and genes associated with resistance. The aim of this study was to assess antimicrobial susceptibility profiles of members of Enterobacteriaceae isolated from wastewater of health facilities, abattoir and downstream water bodies. A total of 24 wastewater samples were collected from the Menilik II Referral Hospital, Kebena River, Tikur Anbessa Specialized Hospital, Kality WWTP, Addis Ababa Abattoir and Little Akaki River on two occasions. Isolation of different Enterobacteriaceae was conducted according to standard procedures using selective media. Identification of Enterobacteriaceae was done by using biochemical test and API 20E. Susceptibility of isolates to a panel of 12 antimicrobials was investigated using disc diffusion assay and selected MDR isolates were also tested for production of extended spectrum beta-lactamase and carbapenemase using double disc synergy test and modified carbapenem inactivation assay respectively. A total of 54 bacteria isolates belonging to Enterobacteriaceae family were identified: E. coli (32%), Salmonella spp. (23%), Klebsiella pneumoniae (15%), Enterobacter aerogenes (11%), Citrobacter spp. (7%), Klebsiella oxytoca (6%) and Enterobacter cloacae (6%), respectively. The highest AMR index of 1 was recorded for Citrobacter isolate from TASH wastewater followed by 0.91 for E. coli from the same source. All isolates were resistant to 2 or more antimicrobial tested. Multi drug resistance (MDR) to several antimicrobials was recorded, particularly in isolates obtained from hospital water samples and it was more common in Citrobacter and E. coli isolates. Extended spectrum beta-lactamase x (ESBL) production was detected in 27.3% of MDR isolates all of which were obtained from hospital effluents, whereas none of the isolates were carbapenemase producers. This study showed the abundance of antimicrobial resistant Enterobacteriaceae in wastewater from Hospital, Abattoir and downstream water bodies. Moreover, hospital effluents contain highest fraction of antimicrobial resistant bacteria which are released to receiving water bodies, posing public health threat.



Antimicrobial Resistance, Enterobacteriaceae, Antimicrobial Resistance Index, Wastewater