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This study evaluated the occurrence of extended-spectrum β-lactamases (ESBL) and associated resistance genes, integrons, and plasmid types as well as the genetic relatedness of enterobacterial isolates in the wastewater treatment plant (WWTP) of La Charguia, Tunis City (Tunisia). One-hundred water samples were collected at different points of the sewage treatment process during 2017–2019. Antimicrobial susceptibility was conducted by disc-diffusion method. blaCTX-M, blaTEM and blaSHV genes as well as those encoding non-β-lactam resistance, the plasmid types, occurrence of class1 integrons and phylogenetic groups of Escherichia coli isolates were determined by PCR/sequencing. Genomic relatedness was determined by MLST for selected isolates. Fifty-seven ESBL-producer isolates were recovered (47 E. coli, eight Klebsiella pneumoniae, one of the Citrobacter freundii complex and one of the Enterobacter cloacae complex). CTX-M-15 was the most frequently detected ESBL, followed by CTX-M-27, CTX-M-55 and SHV-12. One E. coli isolate harboured the mcr-1 gene. The following phylogroups/STs were identified among ESBL-producing E. coli isolates: B2/ST131 (subclade-C1), A/ST3221, A/ST8900, D/ST69, D/ST2142, D/ST38, B1/ST2460 and B1/ST6448. High number of isolates harboured the class 1 integrons with various gene cassette arrays as well as IncP-1 and IncFIB plasmids. Our findings confirm the importance of WWTPs as hotspot collectors of ESBL-producing Enterobacteriaceae with high likelihood spread to human and natural environment.

Hospital wastewater (HWW) represents a major source of the diffusion of many antibiotics and some toxic pathogenic microorganisms in the aquatic environment. Sanitation services play a critical role in controlling transmission of numerous waterborne pathogens, especially enteric human adenoviruses (HAdVs) that can cause acute gastroenteritis. This study intended to evaluate the human adenoviruses (HAdVs) detection rates, to determine the genotype of these viruses and to assess the efficiency of HAdVs removal in hospital pilot wastewater treatment plant (PWWTP) in Tunis City, Tunisia. Therefore, hospital wastewater samples (n = 102) were collected during the study year from the two biological wastewater treatment techniques: natural oxidizing ponds and the rotating biological disks or biodisks. Nested polymerase chain reaction (Nested PCR) was used to evaluate the HAdVs detection rates. The genotype of HAdVs positive samples was achieved by the sequencing of the PCR products. HAdVs were detected in 64% (65/102) of positive wastewater samples. A substantial increase in the frequencies of HAdVs was observed at the exit of the two wastewater treatment techniques studied. The typing of HAdVs species F showed the occurrence of only HAdVs type 41. This data acquired for the first time in Tunisia showed high persistence and survival of HAdVs in the two biological wastewater treatment techniques experienced, and mainly highlighted the poor virological quality of the treated wastewater intended for recycling, agriculture reuse, and discharges into the natural receiving environments. Consequently, tertiary wastewater treatment appeared necessary in this case to decrease the load of enteric viruses flowing in the water environment.