Prevalence and antibiotic resistance of Pseudomonas aeruginosa in water samples in central Italy and molecular characterization of oprD in imipenem resistant isolates

Abstract

ScopeThis study aimed to analyse the prevalence, antibiotic resistance and genetic relatedness of P. aeruginosa isolates obtained from potable and recreational water samples (n. 8,351) collected from different settings (swimming pools, n. 207; healthcare facilities, n 1,684; accommodation facilities, n. 1,518; municipal waterworks, n. 4,500; residential buildings, n. 235). Possible mechanisms underlying resistance to imipenem, with particular focus on those involving oprD-based uptake, were also explored.Methods and resultsIsolation and identification of Pseudomonas aeruginosa was performed according to the standardized procedure UNI EN ISO 16266:2008 followed by PCR confirmation. Antibiotic Susceptibility testing was conducted according to EUCAST standardized disk diffusion method. Genetic relatedness of strains was carried out by RAPD. The sequence of the oprD gene was analyzed by standard method. Fifty-three samples (0.63%) were positive for P. aeruginosa, of which 10/207 (4.83%) were from swimming pools. Five isolates (9.43%) were resistant to imipenem, one to Ticarcillin + Clavulanate, one to both Piperacillin and Ticarcillin + Clavulanate. The highest isolation rate of imipenem resistant P. aeruginosa was observed in swimming pool water. Identical RAPD profiles were found in isolates from the same location in the same year or even in different years.ConclusionsImipenem resistant strains were identified as carbapenemase-negative and resistance has been associated with inactivating mutations within the oprD gene, with a concomitant loss of porin. RAPD results proved that a water system can remain colonized by one strain for long periods and the contamination may be difficult to eradicate.This study has revealed the presence of P. aeruginosa in different water samples, including resistant strains, especially in swimming pools, and confirmed the role of porins as a contributing factor in carbapenem resistance in Gram-negative bacteria.

Virulence properties and antimicrobial resistance of Pseudomonas aeruginosa isolated from cave waters at Roraima Tepui, Guayana Highlands

“…2016; Schiavano et al . 2017). Additionally, the production of AmpC betalactamases was phenotypically screened in LG11 as one of the intrinsic resistance mechanisms of P. aeruginosa , resulting in AmpC partially/fully derepressed with resistance to ceftazidime and piperacillin/tazobactam.…”

“…Our results confirm the continuous spread of P. aeruginosa in waters with resistance to front‐line antibiotics such as imipenem (Schiavano et al . 2017), and point to this bacterium as a potential reservoir of virulence genes and multi‐resistance in pristine aquatic environments. Future studies should determine the main mechanisms of resistance (intrinsic or acquired) in these ecosystems.…”

“…Recent studies suggest that water systems are increasingly becoming a preferred interface in the epidemiology of P. aeruginosa (Flores et al 2014;Vaz-Moreira et al 2014;Pappa et al 2016;Schiavano et al 2017;Anversa et al 2019). Environmental or non-pathogenic forms of the bacterium may serve as a storehouse of genetic determinants which, if transferred to other bacterial strains, may confer novel virulence capabilities (Moradali et al 2017).…”

“…2016; Schiavano et al . 2017), there is limited information from pristine ecosystems. The Guayana Highlands are one of the few remaining pristine environments on Earth.…”

“…Although several studies have identified this pathogen carrying antimicrobial resistance in different water sources (Vaz-Moreira et al 2014;Pappa et al 2016;Schiavano et al 2017), there is limited information from pristine ecosystems. The Guayana Highlands are one of the few remaining pristine environments on Earth.…”