MULTIDRUG-RESISTANT PSEUDOMONAS AERUGINOSA – APROBLEM IN HOT TUBS AND WHIRLPOOLS IN CANADA

• Author(s) / Creator(s)

  • Md Murad Mufty

• Objectives:Pseudomonas aeruginosa is one of the most problematic opportunistic pathogens.
  It is resistant to many currently used antibiotics, making it difficult to treat, and resistance may
  transfer to other P. aeruginosa strains. The organism can acquire resistance through horizontal
  gene transfer but is thought to be incompetent in natural transformation.

  Free-living amoebae (FLA) are a critical group of the microbial protozoa community that
  influence biofilm associated bacteria (e.g., P. aeruginosa) in hot tubs and whirlpools. There
  appears to be no study relating to P. aeruginosa`sinteraction with free-living amoebae and its
  general ecology from the water system in the hot tubs and whirlpools.

  Therefore, this study aimed to investigate the antibiotic resistance profiles of P. aeruginosa
  from water in hot tubs and whirlpools and to demonstrate if the P. aeruginosa isolates are
  competent in the uptake of extracellular DNA leading to the transfer of antibiotic resistance,
  and whether FLA may promote early uptake of the extracellular DNA.

  Methods: 45 P. aeruginosa isolates from water in hot tubs and whirlpools were assayed,
  against 36 antibiotic agents, including penicillins, cell wall inhibitors containing extended-
  spectrum beta-lactamases (ESBLs), protein synthesis inhibitors, carbapenems,

  fluoroquinolones, cephalosporins, folic acid synthesis inhibitors, nitrofurans, monobactams
  and aminoglycosides. The resistance was phenotypically assessed using Kirby-Bauer’s disk
  diffusion method, and the results were interpreted according to the Clinical & Laboratory

  Standards Institute (CLSI) guidelines. The prevalence and frequency of antimicrobial
  resistance genes were investigated by PCR.

  The study also examined transformation of naked plasmid extracellular DNA carrying
  antibiotic resistance genes into recipient P. aeruginosa isolates from water in hot tubs and
  whirlpools. In addition, using fluorescent microscopy, the experiment examined in -situ
  interactions of P. aeruginosa with two FLAs - Acanthamoebae polyphaga and Willaertia
  magna on the transformation of the extracellular plasmid DNA to P. aeruginosa isolates.

  Results: All the tested P. aeruginosa isolates were resistant to at least six antibiotics; and with
  all 45 strains possessing a common backbone of resistance to four antibiotics (ampicillin,
  cloxacillin, mecillinam and cephalothin). All strains were resistant to at least three classes of
  antibiotics, designating them as multidrug resistant strains. Some hot tub strains were resistant
  to as many as 10 antibiotics. Worryingly, five isolates were shown to possess carbapenem
  resistance (ertapenem and doripenem). Among the 36 antibiotics tested, 21 antibiotics are
  clinically relevant, and all the isolates were susceptible to those 21 antibiotics except for one
  carbapenem (doripenem), for which only one isolate was resistant to this drug.

  All the tested P. aeruginosa isolates expressed genes present for porin (oprL, oprD), efflux
  pumps (ampC, mexC1,2, mexC3,4), QS (lasl, lasR), T3SS (popB), and T6SS (tssC1). The study
  found most of the P. aeruginosa isolates (89.13%) had effector protein gene exoY, and fewer
  had another two effector protein genes exoS (54.35%) and exoU (34.78%). The biofilm-
  associated gene ndvB was identified in all P. aeruginosa isolates, but no isolate contained
  NDM, the β-lactam biofilm gene.

  The research also demonstrated that P. aeruginosa were competent at taking up plasmid DNA
  containing antibiotic resistance genes from their environment, and stably incorporating this
  DNA into their cellular metabolism. Transformation was observed after 49 days of
  monoculture with plasmid DNA. In contrast, when FLA were present in the culture,
  transformation occurred in only nineto 14 days, albeit only a single experiment was performed,
  and therefore some uncertainty remains as to whether predatory amoeba may induce greater
  rates of transformation in P. aeruginosa.

  Conclusions: This study's results indicate a high frequency of multi-class and multi-drug
  resistance in P. aeruginosa isolated from hot tubs in Alberta. The observation that carbapenem-
  resistant P. aeruginosa were found in hot tubs is of critical concern. Nevertheless, this study
  demonstrated that hot tub isolates were mostly susceptible to the currently used antibiotics
  recommended for treatment of P. aeruginosa infections. The study observed that the P.
  aeruginosa isolates from hot tubs and whirlpools could acquire extracellular plasmid DNA
  containing antibiotic resistance genes through transformation. The results also suggest that the
  presence of FLAs within the same niche as P. aeruginosa may potentially prompt extracellular
  plasmid DNA transformation in P. aeruginosa.

• Date created

  2022-06-27

• Subjects / Keywords

  • P. aeruginosa, antibiotic resistance, hot tub, whirlpool, efflux pump, porin, amoebae, transformation, extracellular DNA.

• Type of Item

  Research Material

• DOI

  https://doi.org/10.7939/r3-zsa1-zz53

• License

  Attribution-NonCommercial 4.0 International