Isolation and identification of antibiotic-resistant bacteria in hospital tap water

Hospital tap water can act as a reservoir of opportunistic and potentially antibiotic-resistant bacteria, yet baseline data on the bacterial communities and antimicrobial resistance profiles of premise-plumbing systems remain scarce in Iraq. This study investigated the bacterial species present in hospital tap water and their antibiotic resistance profiles, with the aim of supporting infection control measures in healthcare settings.

Tap water samples were collected from three hospitals in Babil Governorate, Iraq (Merjan Teaching Hospital, Turkish Hospital, and Al-Jiumhori Hospital) and were processed for heterotrophic plate counts and bacterial isolation. Isolates were identified to the species level using the VITEK 2 Compact automated phenotypic system, and antimicrobial susceptibility was determined on the same platform and interpreted according to Clinical and Laboratory Standards Institute guidelines.

A total of 11 bacterial isolates were recovered. The highest bacterial load was recorded in the Turkish Hospital sample (3.43 × 10⁴ CFU/mL). The identified species comprised Granulicatella elegans, Acinetobacter haemolyticus, Pseudomonas alcaligenes, Moraxella lacunata, Francisella tularensis, Aeromonas sobria, Pseudomonas stutzeri, and Sphingomonas paucimobilis. The single Gram-positive isolate, G. elegans, showed the highest resistance (10 of 14 agents tested; 71.4%), whereas the Gram-negative isolates were largely susceptible, with only sporadic resistance detected in P. stutzeri and M. lacunata.

Because several species were represented by a single isolate and identification relied on an automated phenotypic platform, these resistance estimates are descriptive and should be interpreted with caution. The findings nonetheless confirm the presence of opportunistic and potentially resistant bacteria in hospital tap water and underscore the need for routine microbiological monitoring and improved water safety protocols.