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The diversity of Salmonella was analysed in biofilm and water samples from the spring and slough arms of Spring Lake, the headwaters of the San Marcos River, Texas, during the drought of 2011, with only one potential run-off event at the beginning of the study. Salmonellae were detected in semiselective enrichment cultures by end-point PCR during the entire sampling period of (11 sampling events during 2 months). From the spring arm site, 73% of the biofilms and 41% of the water samples were positive for salmonellae, while only 9% of the biofilms and 23% of the water samples were positive from the slough arm site. Salmonellae could be isolated from all positive samples, with higher diversity in biofilms compared with water samples and more strains obtained from the spring arm than from the slough arm. Differences between sites were generally caused by less frequently detected isolates, while the majority of isolates that were present in both biofilms and water from both sites was represented by three strains only. Quantification attempts by quantitative PCR directly in samples without prior enrichment did not result in a reliable detection of salmonellae, suggesting that numbers in all samples were below the detection limit. [ABSTRACT FROM AUTHOR]

Salmonellae are pathogenic bacteria often detected in waters impacted by human or animal wastes. in order to assess the fate of salmonellae in supposedly pristine environments, water and natural biofilm samples along with snails (Tarebia granifera) and crayfish (Procambarus clarkia) were collected before and up to 7 days following four precipitation events from sites within the headwater springs of Spring Lake, San Marcos, TX. The samples were analyzed for the presence of salmonellae by polymerase chain reaction (PCR) after semi-selective enrichment. Salmonellae were detected in one water sample directly after precipitation only, while detection in ten biofilm and two crayfish samples was not related to precipitation. Salmonellae were not detected in snails. Characterization of isolates by rep-PCR revealed shared profiles in water and biofilm samples, biofilm and crayfish samples, and biofilm samples collected 23 days apart. These results suggest that salmonellae are infrequently washed into this aquatic ecosystem during precipitation runoff and can potentially take up residency in biofilms which can help facilitate subsequent long-term persistence and eventual transfer through the food chain. [ABSTRACT FROM AUTHOR]

Sediments and water from the spring and slough arm of Spring Lake, the pristine headwaters of the San Marcos River, Texas, were analyzed for Salmonellae by culture and molecular techniques before and after three major precipitation events, each with intermediate dry periods. Polymerase chain reaction (PCR)-assisted analyses of enrichment cultures detected Salmonellae in samples after all three precipitation events, but failed to detect them immediately prior to the rainfall events. Detection among individual locations differed with respect to the precipitation event analyzed, and strains isolated were highly variable with respect to serovars. These results demonstrate that rainwater associated effects, most likely surface runoff, provide an avenue for short-term pollution of aquatic systems with Salmonellae that do not, however, appear to establish for the long-term in water nor sediments. [ABSTRACT FROM AUTHOR]

A nested PCR protocol was used to analyze five endemic salamander species from Central Texas for the presence of the emerging pathogen, chytrid fungus ( Batrachochytrium dendrobatidis). Chytrid fungus was detected from samples of each of the five species sampled: with low abundance, in the Texas salamander ( Eurycea neotenes) (1 positive out of 16 individuals tested; 1/16), the Blanco River Springs salamander ( E. pterophila) (1/20), the threatened San Marcos salamander ( E. nana) (1/17), and the endangered Barton Springs salamander ( E. sosorum) (1/7); much higher abundance was obtained for the Jollyville Plateau salamander ( E. tonkawae) (6/14), which has recently been petitioned for addition to the USA endangered species list. With one exception, sequences of PCR products were identical to the 5.8S rRNA gene, and nearly so for the flanking internal transcribed spacer (ITS) regions of B. dendrobatidis which confirmed the detection of chytrid fungus, and thus demonstrated the presence of this pathogen in populations of endangered species in Central Texas. These confirmations were obtained from nonconsumptive tail clippings which confirms the applicability of historically collected samples from other studies in the examination of the fungus across time. [ABSTRACT FROM AUTHOR]

The diversity and distribution of salmonellae in freshwater biofilms were analyzed at a fine scale (i.e. in 20 locations from a 324 cm(2) area) for two sites in San Marcos, TX. A concrete storm water overflow channel (City Park) was sampled 4 times and a concrete surface in the spring-fed headwaters of the San Marcos River (Spring Lake) 5 times between April and September 2009, and each biofilm sample analyzed by a combination of traditional enrichment methods and molecular techniques. PCR detection of the invA gene, that encodes a protein of a type III secretion system present in salmonellae, after semi-selective enrichment of salmonellae was achieved in biofilms from all 20 locations at the City Park site, with locations generally being positive 2-3 times out of 4 sampling times for a total of 59% positive samples. InvA gene fragment detection in biofilms was less frequent for the 5 sampling times and 20 locations from the Spring Lake site (18% of all samples), with 1 sampling time being entirely negative and 8 locations remaining negative throughout the study. Rep-PCR fingerprinting of 491 Salmonella isolates obtained from both sites resulted in 30 distinct profiles, with 26 and 7 profiles retrieved from City Park and Spring Lake samples, respectively, and thus with 3 profiles present at both sites, and multiple strains frequently obtained from single locations at both sites. The composition of Salmonella strains in the area analyzed changed in time with large differences between early (April, June) and late sampling times (September) within and among sites, except for one strain (S12) that was present at almost all sampling times at both sites, though often at different locations within the area analyzed. These results demonstrate the presence of salmonellae in natural biofilms and a significant micro-heterogeneity with differences in diversity and persistence of salmonellae., (Copyright © 2011 Elsevier GmbH. All rights reserved.)

Sediments and water from the slough arm of Spring Lake, the headwaters of the San Marcos River, Texas, USA, as well as swabs from biofilms on carapaces and from the cloacae of 18 common musk turtles (Sternotherus odoratus), 21 red-eared sliders (Trachemys scripta elegans), nine Texas river cooters (Pseudemys texana), one snapping turtle (Chelydra serpentina serpentina), and three Guadalupe spiny soft-shell turtles (Apalone spinifera guadalupensis), caught at the same site, were analyzed for salmonellae by culture and molecular techniques. Although enrichment cultures from sediment and water samples were negative for salmonellae in polymerase chain reaction (PCR)-based analyses, this technique detected salmonellae in the enrichments from both carapaces and cloacae of 11 musk turtles (61%), eight red-eared sliders (38%), and the snapping turtle. Salmonellae could also be detected in the enrichments from the carapaces of two additional red-eared sliders and two Texas river cooters; the remaining samples were negative. Further characterization of isolates obtained from the enrichment cultures of seven selected individuals that represented all turtle species with salmonellae confirmed the presence of Salmonella enterica subspecies enterica, with serovars Rubislaw, Newport, Gaminara, and Thompson identified. These results demonstrate the presence of different strains of potentially human pathogenic salmonellae naturally occurring on several turtle species with different life histories even within supposedly pristine environments.

Sediments and water from the pristine headwaters of the San Marcos River, Texas, USA, as well as swabs from biofilms on the carapace and from the cloacae of 17 musk turtles (Sternotherus odoratus) and one snapping turtle (Chelydra serpentina serpentina) caught at the same site, were analysed for salmonellae by culture and molecular techniques. Whereas enrichment cultures from sediment and water samples were negative for salmonellae in PCR- and in situ hybridization-based analyses, both techniques detected salmonellae after enrichments from both carapace and cloacae of nine (i.e. of 53%) musk turtles. Further characterization of 10 isolates obtained from the enrichment cultures of four selected individuals and confirmed as salmonellae by PCR analysis was achieved by fingerprinting techniques (rep-PCR). The results show differences between individuals and, in one case, variation among isolates from a single individual. All isolates from two individuals displayed identical profiles. These profiles were different from those obtained from the isolates of the third individual, which were, themselves, also identical for all isolates. Salmonellae were much more diverse in samples from the carapace of the last individual with five different rep-PCR profiles retrieved. Serotyping of seven isolates representative for each rep-PCR profile identified all isolates as representing Salmonella enterica subspecies enterica serotype Rubislaw, which demonstrates the presence of different strains of potentially human pathogenic salmonellae naturally occurring on turtles even within pristine environments. The frequent detection of these organisms in biofilms on the carapace opens the door for speculations on the role of this habitat as a reservoir for salmonellae, and on potential implications for turtles acting as a dispersal vector.