Diversity of bacteria carrying antibiotic resistance genes in hospital raw sewage in Southeastern Brazil

In recent decades, antibiotic-resistant bacteria (ARB) emerged and spread among humans and animals worldwide. In this study, we evaluatedthe presence of ARB and antibiotic resistance genes (ARGs) in the raw sewage of two hospitals in Brazil. Sewage aliquots were inoculated in aselective medium with antibiotics. Bacterial identification was performed by MALDI-TOF and ARGs were assessed by PCR. A total of 208strains from both hospitals were isolated (H1=117; H2=91). A wide variety of Enterobacterales and non-Enterobacterales species were iso-lated and most of them were Enterobacter spp. (13.0%), Proteus mirabilis (10.1%), and Klebsiella pneumoniae (9.6%). blaTEM and blaK PC were the most frequent beta-lactamase-encoding genes and the predominant macrolide resistance genes were mph(A) and mel. Many species had the three tetracycline resistance genes (tetD, tetM, tetA) and strB was the prevalent aminoglycoside resistance gene. Two Staphylococ-cus haemolyticus strains had the mecA gene. Quinolone, colistin, and vancomycin resistance genes were not found. This study show thathospital raw sewage is a great ARB and ARG disseminator. Strict monitoring of hospital sewage treatment is needed to avoid the spreadof these genes among bacteria in the environment.