Abstract
The aim of the study was to elucidate the association between the zoonotic pathogen Salmonella and a population of land iguana, Colonophus subcristatus, endemic to Galápagos Islands in Ecuador. We assessed the presence of Salmonella subspecies and serovars and estimated the prevalence of the pathogen in that population. Additionally, we investigated the genetic relatedness among isolates and serovars utilising pulsed field gel electrophoresis (PFGE) on XbaI-digested DNA and determined the antimicrobial susceptibility to a panel of antimicrobials. The study was carried out by sampling cloacal swabs from animals (n = 63) in their natural environment on in the island of Santa Cruz. A high prevalence (62/63, 98.4%) was observed with heterogeneity of Salmonella subspecies and serovars, all known to be associated with reptiles and with reptile-associated salomonellosis in humans. Serotyping revealed 14 different serovars among four Salmonella enterica subspecies: S. enterica subsp. enterica (n = 48), S. enterica subsp. salamae (n = 2), S. enterica subsp. diarizonae (n = 1), and S. enterica subsp. houtenae (n = 7). Four serovars were predominant: S. Poona (n = 18), S. Pomona (n = 10), S. Abaetetuba (n = 8), and S.Newport (n = 5). The S. Poona isolates revealed nine unique XbaI PFGE patterns, with 15 isolates showing a similarity of 70%. Nine S. Pomona isolates had a similarity of 84%. One main cluster with seven (88%) indistinguishable isolates of S. Abaetetuba was observed. All the Salmonella isolates were pan-susceptible to antimicrobials representative of the most relevant therapeutic classes. The high prevalence and absence of clinical signs suggest a natural interaction of the different Salmonella serovars with the host species. The interaction may have been established before any possible exposure of the iguanas and the biocenosis to direct or indirect environmental factors influenced by the use of antimicrobials in agriculture, in human medicine or in veterinary medicine.
Highlights
Salmonella is known to be associated with free-living and captive reptiles [1,2,3,4], and sometimes has been detected at high prevalence rates, among species of the order Squamata [5], including Iguanidae [6,7]
The Salmonella isolates detected in what is considered a natural land iguana population revealed a wide spectrum of subspecies and serovars
The land iguana population on Santa Cruz island does not reach the densities occurring on other islands such as Santa Feand Plaza Sur, almost all animals harboured Salmonella, at a prevalence even higher than reported in land iguanas sampled on these other two minor islands of the Galapagos island chain, in a recent small-scale study [17]
Summary
Salmonella is known to be associated with free-living and captive reptiles [1,2,3,4], and sometimes has been detected at high prevalence rates, among species of the order Squamata [5], including Iguanidae [6,7]. Human exposure to reptiles and Iguanidae is currently considered a significant risk factor for Salmonella infections [10,11] and is frequently reported causing clinical disease [7,12]. The aim of the study was to (1) elucidate the association of the zoonotic pathogen Salmonella spp. in a population of the endemic land iguana, Colonophus subcristatus from Galapagos Islands in Ecuador. (2) we assessed the presence of Salmonella subspecies and serovars and estimated the prevalence of the pathogen in that population of land iguanas. We (3) investigated the genetic relatedness among isolates and serovars utilising pulsed field gel electrophoresis (PFGE) and (4) determined the antimicrobial susceptibility to a panel of antimicrobials
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