Seasonal dietary changes relate to gut microbiota composition depending on the host species but do not correlate with gut microbiota diversity in arthropod-eating lizards.

The animal gut microbiota is strongly influenced by environmental factors that shape their temporal dynamics. Although diet is recognized as a major driver of gut microbiota variation, dietary patterns have seldom been linked to gut microbiota dynamics in wild animals. Here, we analysed the gut microbiota variation between dry and rainy seasons across four Sceloporus species (S. aeneus, S. bicanthalis, S. grammicus and S. spinosus) from central Mexico in light of temporal changes in diet composition. The lizard microbiota was dominated by Firmicutes (now Bacillota) and Bacteroidota, and the closely related species S. aeneus and S. bicanthalis shared a great number of core bacterial taxa. We report species-specific seasonal changes in gut microbiota diversity and composition: greater alpha diversity during the dry compared to the rainy season in S. bicanthalis, the opposite pattern in S. aeneus, and no seasonal differences in S. grammicus and S. spinosus. Our findings indicated a positive association between gut bacterial composition and dietary composition for S. bicanthalis and S. grammicus, but bacterial diversity did not increase linearly with dietary richness in any lizard species. In addition, seasonality affected bacterial composition, and microbial community similarity increased between S. aeneus and S. bicanthalis, as well as between S. grammicus and S. spinosus. Together, our results illustrate that seasonal variation and dietary composition play a role in shaping gut microbiota in lizard populations, but this is not a rule and other ecological factors influence microbiota variation.

A virulent clone of Devriesea agamarum affects endangered Lesser Antillean iguanas (Iguana delicatissima).

Infectious diseases affecting wildlife are drivers of global biodiversity loss. Here we report a bacterial threat to endangered wild reptiles. Since April 2011, a severe skin disease has affected free-ranging, endangered Lesser Antillean iguanas (Iguana delicatissima) on the French Caribbean island of Saint Barthélemy and we identified Devriesea agamarum as the causative agent. The presence of this bacterium was also demonstrated in healthy lizards (anoles) co-inhabiting the island. All isolates from the iguanas corresponded to a single AFLP genotype that until now has exclusively been associated with infections in lizard species in captivity. The clonal relatedness of the isolates and recent emergence of the disease suggest recent arrival of a virulent D. agamarum clone on the island. The presence of healthy but infected lizards suggests the presence of asymptomatic reservoir hosts. This is the first description of a bacterial disease that poses a conservation threat towards free-ranging squamates.

Does adaptive radiation of a host lineage promote ecological diversity of its bacterial communities? A test using gut microbiota of Anolis lizards.

Adaptive radiations provide unique opportunities to test whether and how recent ecological and evolutionary diversification of host species structures the composition of entire bacterial communities. We used 16S rRNA gene sequencing of faecal samples to test for differences in the gut microbiota of six species of Puerto Rican Anolis lizards characterized by the evolution of distinct 'ecomorphs' related to differences in habitat use. We found substantial variation in the composition of the microbiota within each species and ecomorph (trunk-crown, trunk-ground, grass-bush), but no differences in bacterial alpha diversity among species or ecomorphs. Beta diversity analyses revealed subtle but significant differences in bacterial composition related to host phylogeny and species, but these differences were not consistently associated with Anolis ecomorph. Comparison of a trunk-ground species from this clade (A. cristatellus) with a distantly related member of the same ecomorph class (A. sagrei) where the two species have been introduced and are now sympatric in Florida revealed pronounced differences in the alpha diversity and beta diversity of their microbiota despite their ecological similarity. Comparisons of these populations with allopatric conspecifics also revealed geographic differences in bacterial alpha diversity and beta diversity within each species. Finally, we observed high intraindividual variation over time and strong effects of a simplified laboratory diet on the microbiota of A. sagrei. Collectively, our results indicate that bacterial communities are only weakly shaped by the diversification of their lizard hosts due to the strikingly high levels of bacterial diversity and variation observed within Anolis species.

Salmonella Isolates in the Introduced Asian House Gecko (Hemidactylus frenatus) with Emphasis on Salmonella Weltevreden, in Two Regions in Costa Rica.

The Asian house gecko Hemidactylus frenatus has been widely introduced in Costa Rica and tends to establish in human settlements. Some studies in other invaded countries have suggested that this gecko plays a significant role in the epidemiology of salmonellosis and it is of value to public health. To our knowledge, no studies have examined Salmonella from this species in Costa Rica. Therefore, we collected 115 geckos from houses in two Costa Rican regions. We examined gut contents for Salmonella through microbiological analysis. Presumptive Salmonella spp. were sent to a reference laboratory for serotyping and antimicrobial susceptibility testing. Molecular typing was also conducted with the main Salmonella isolates of zoonotic relevance in Costa Rica. H. frenatus was found in 95% of the houses surveyed. Salmonella was isolated in 4.3% of the samples, and four zoonotic serovars were detected. None of the isolates were resistant to the antibiotics most frequently used for salmonellosis treatment in Costa Rica. All Salmonella isolates from the lower gut of H. frenatus are associated with human salmonellosis. Pulsotypes from Salmonella enterica serotype Weltevreden were identical to the only clone previously reported from human samples in Costa Rica. Molecular typing of Salmonella Weltevreden suggested that H. frenatus harbors a serovar of public health importance in Costa Rica. Results demonstrated that H. frenatus plays a role in the epidemiology of human salmonellosis in two regions of Costa Rica. However, more detailed epidemiological studies are needed to understand better the role of the Asian house gecko with human salmonellosis, especially caused by Salmonella Weltevreden, and to quantify its risk in Costa Rica accurately.

Empyema of preexisting subdural hemorrhage caused by a rare salmonella species after exposure to bearded dragons in a foster home.

An infant had a subdural empyema caused by the rare Salmonella species enterica subspecies houtenae (IV) serotype 44:z4,z23:- after only indirect exposure to exotic reptiles in her foster home. Infants recovering from preexisting subdural hematoma are at risk for development of empyema.

High prevalence of Salmonella in tegu lizards (Tupinambis merianae), and susceptibility of the serotypes to antibiotics.

Species of tegu (Tupinambis) are the largest lizards in South America. Large numbers of these lizards are hunted; there is a vigorous trade in their skins and the meat is consumed by rural and native peoples. The animals are also bred in captivity, an economic activity for rural populations which can help in the animals' conservation. Faecal samples from 30 captive-born tegus were analysed for the presence of Salmonella in two separate samplings. In the first analysis, samples from 26 animals (87%) yielded Salmonella enterica of which 23% were of Rubislaw serotype; 20% Carrau and Agona serotypes; 7% Infantis and Saint-Paul serotypes; 3% Panama and Brandenburg serotypes; 10% were S. enterica subsp. enterica and 7% were rough form. In the second analysis, four tegus (13%) which had been negative in the first sampling were positive, thus, 100% of the animals studied carried the bacterium. Antibiotic susceptibility showed resistance to sulfonamide in 82% of the isolates, streptomycin in 64%, tetracycline in 6% and Chloramphenicol in 20%. Two animals carried strains of the same serotype with different patterns of antibiotic susceptibility. Although it is well known that reptiles are a significant source of Salmonella, to our knowledge, its prevalence in tegu has not been studied previously.

Hematology, blood chemistry, and bacteriology of the free-ranging Mexican beaded lizard (Heloderma horridum).

Blood samples from 16 adult, wild Mexican beaded lizards were obtained for complete blood count and serum biochemical analysis. In addition, both oral and cloacal swab samples were collected and submitted for bacteriologic culture. This is the first report of hematologic and bacterial data from free-living beaded lizards. This information will serve as baseline reference values for future health assessment studies in conservation, captive breeding, and research programs.

Lizards in the ecology of salmonellosis in Panama.

Enteropathogenic bacteria was isolated from 131 of 447 (29.4%) neotropical Panamanian lizards belonging to 34 species of seven families. Overall, 147 strains of bacteria were isolated comprising 26 Salmonella and 10 Arizona serotypes. Gymnopthalmus speciosus had the highest infection rate, 12 of 13 individuals (92.3%), whereas Gonatodes fuscus exhibited the lowest, 1 of 18 (5.6%). The highest infection was detected in lizards whose behavioral patterns were secretive (42.0%) and terrestrial (42.6%), whereas the lowest infection was among the scansorial lizards (17.5%). Rates were highest during the dry season, from January through April. Many neotropical Panamanian lizards were multiply infected by Salmonella an Arizona strains representing representing a wide range of serotypes. Infected lizards were distributed in areas varying from remote rural and forested regions to urban developments, offering a potentially important reservoir of enteropathogenic bacteria known to cause infection in man and domestic animals.