Introduction. Transmission of antibiotic resistant bacteria (ARB) and opportunistic pathogens to patients and health care workers can occur by hospital environmental sources such as colonized surfaces or bacterial biofilms present in sinks and shower drains. Hospital wastewater (WW) receives all run-off water from hospital sinks and collects feces from patients and hospital staff. Hospital WW could thus be an indicator of ARB and pathogens present in the hospital environment. Their monitoring is usually carried out by sampling surfaces, followed by routine culturing methods, but it does not include WW or biofilms collected from sink drains. Here, we implemented culture-dependent and culture-independent approaches to assess hospital sink biofilms and WW biofilms as potential sources of ARB accumulation and transmission. Methods. Sampling was performed monthly from January to May 2023 in both the neonatal and the adult ICUs of the Grenoble University Hospital. Four sink biofilms from patient rooms, WW and WW biofilms were collected during each campaign in each respective unit. Our culturing approach focused on the isolation of emerging highly resistant bacteria (EHRB) such as carbapenemase-producing Pseudomonas aeruginosa and Enterobacteriaceae, and glycopeptide-resistant Enterococcus. Samples were cultured on selective and non-selective media. The isolated species were identified by MALDI-TOF and antibiotic susceptibly tests were performed by disks diffusion method. The resistome was studied using qPCR targeting both the class 1 integron integrase gene, which is a clinically important antibiotic resistance marker, and the carbapenamase-like OXA-48 gene. Results. The culturable fraction revealed a low bacterial diversity, with 1/ an average of 3 [0 – 6] different bacterial species per sink in both the neonatal- and the adult ICUs, and 2/ an average of 13 [10 – 16] different bacterial species per WW and WW biofilms in both wards. No carbapenemase-producing strains nor glycopeptide-resistant Enterococcus were isolated in the sampled sink biofilms in both the neonatal- and the adult ICUs. However, eight carbapenemase producing Enterobacteriaceae could be isolated and were identified to carry OXA-48 or VIM carbapenemase in WW and WW biofilm in both the adult and the neonatal- ICUs. qPCR detected the OXA-48-like gene in all WW and WW biofilm samples, even in those samples from which no carbapenemase producing strains could be isolated. Interestingly, the class 1 integron integrase resistance marker was detected in more than 85% of all sinks and in all WW and WW biofilm samples. Conclusions. Our preliminary results showed that hospital WW and WW biofilms contain EHRB, which is a cause of major concern. No highly resistant bacteria were isolated from sink biofilms by culture. However, culture-independent analysis of the resistome showed that sink biofilms can act as a reservoir for the class 1 integron integrase gene, which is 1/ a genetic element that carries antibiotic resistance genes (ARGs), 2/ that is associated with their transmission in Enterobacteriaceae and 3/ which is yet impossible to assess by routine culturing approaches. Correlation of these findings with the infection incidence, both the antibiotic treatments and the hygiene protocols administered at the tested ICU units will reveal whether this translates to an actual transmission risk for ARB or rather “just” an accumulation of the latter, and whether hospital WW can be used as a monitoring tool for the risk prediction of ARB carriage in the hospital and their dissemination into the environment.