Prevalence and genetic variability of Plesiomonas shigelloides in temperate climate surface waters of the Pannonian Plain

Abstract

Plesiomonas shigelloides, a Gram-negative bacterium and the causative agent of intestinal diseases and extraintestinal infections in humans and animals, is most frequently found in aquatic environments in tropical or subtropical areas. The present study was designed to establish the prevalence and genetic variability of P. shigelloides in surface waters (lakes, rivers, ponds, inlets and canals) located in a temperate climate zone, namely the Pannonian Plain of the northern part of Serbia and southern part of Hungary. The strains were isolated directly by plating samples on inositol-brilliant green-bile agar with neutral red or phenol red as indicators. Our results indicate that phenol red effectively facilitates differentiation of P. shigelloides from other bacteria. A number of samples were enriched using alkaline peptone water broth, peptone inositolbile broth and tetrathionate broth. The recovery of the isolates was more successful with the first medium. Out of a total of 51 water samples collected from 28 different locations, 22 samples (43.1%) were found positive for P. shigelloides. Among the 37 isolated strains, 34 were from lakes (Satrinci, Ludas, Panonija, Krivaja, Pecs, Kapetanski rit, Pavlovci, Kovacsszenaja, Dobrodol, Vranjas, Borkovac, Hermann Otto, Sot, Selevrenac, Zobnatica, Palic, Orfui, Jarkovci, Conoplja) and 3 were from rivers (Danube, Sava). The strains were identified by phenotypic characteristic or by the VITEK2 system and confirmed by PCR using 23S rRNA species-specific oligos. The strains showed a high genetic variability, displaying a variety of RAPD profiles. Our results reveal for the first time a high prevalence of genetically diverse P. shigelloides populations in surface waters located in the temperate climate of central and southeastern Europe.

Molecular Characterization, Intra-Species Diversity and Abundance of Freshwater Plesiomonas shigelloides Isolates

“…This connotes differences in the occurrence of P. shigelloides strains in nature. Heterogeneity in P. shigelloides has been reported by many studies, even at the same serovar level [ 8 , 9 , 37 ]. However, establishing unique identities that discriminate pathogenic strains from nonpathogenic strains has been a challenge.…”

“…The observed high recovery rate compared with previous studies in part could be attributed to a combined use of filtration technique and Inositol Brilliant Green Bile Agar for the isolation of P. shigelloides in this study. Most previous studies used some other media and culture techniques [ 37 , 38 ] that allowed P. shigelloides to compete with a host of other bacteria, which, in most cases, have higher growth advantages in the media compared with P. shigelloides . Some rates of positive detection of P. shigelloides from river, well, or pond water in other works include 40.7% [ 37 ], 16.67% (4/24) in Rio de Janeiro City in Brazil [ 38 ], 0.6% (well) and 7.4% (pond) in Zaria, Nigeria [ 39 ], 12.8% in Japan [ 40 ], and 13.3% in Dhaka, Bangladesh [ 41 ].…”

“…Most media for isolation of coliform and members of the Enterobacteriaceae allow the growth of P. shigelloides with varying recovery efficiencies and specificities. These media include deoxycholate-hydrogensulphide lactose agar [ 38 ], Salmonella-Shigella agar [ 34 , 43 , 44 ], MacConkey [ 43 , 45 , 46 ], Hektoen enteric agar [ 45 ], modified Salmonella-Shigella agar [ 40 , 44 ], deoxycholate citrate agar [ 46 ], taurocholate tellurite gelatin agar [ 41 ], xylose lysine deoxycholate agar [ 39 , 45 ], Endo agar [ 47 ], Plesiomonas differential agar [ 37 , 41 ], and peptone inositol bile and broth tetrathionate broth without iodine [ 37 ].…”

“…The relative high water temperatures, known to be favorable for P. shigelloides multiplication, may have resulted in the higher rate of detection. However, isolation of P. shigelloides from freshwater water samples in the temperate and colder regions of the world, such as Czech Republic [ 48 ], Hungary [ 37 ]; the Netherlands [ 49 ], Slovakia [ 50 ], subpolar region of Sweden [ 47 , 50 ], and Serbia [ 37 ], has been reported.…”