RESUMO
The main objective of this study was to characterize the tet(X) genes, which encode a monooxygenase that catalyzes the degradation of tetracycline antibiotics, carried by the resistant strains FP105 and FP233-J200, using whole-genome sequencing analysis. The isolates were recovered from fin lesion and kidney samples of diseased rainbow trout Oncorhynchus mykiss, during two Flavobacteriosis outbreaks occurring in freshwater farms located in Southern Chile. The strains were identified as Epilithonimonas spp. by using biochemical tests and by genome comparison analysis using the PATRIC bioinformatics platform and exhibited a minimum inhibitory concentration (MIC) of oxytetracycline of 128 µg/mL. The tet(X) genes were located on small contigs of the FP105 and FP233-J200 genomes. The sequences obtained for the tet(X) genes and their genetic environment were compared with the genomes available in the GenBank database of strains of the Chryseobacterium clade belonging to the Flavobacterium family, isolated from fish and carrying the tet(X) gene. The Tet(X) proteins synthesized by the Chilean Epilithonimonas strains showed a high amino acid similarity (range from 84% to 100%), with the available sequences found in strains belonging to the genus Chryseobacterium and Flavobacterium isolated from fish. An identical neighborhood of tet(X) genes from both Chilean strains was observed. The genetic environment of tet(X) observed in the two strains of Epilithonimonas studied was characterized by the upstream location of a sequence encoding a hypothetical protein and a downstream located alpha/beta hydrolase-encoding gene, similar to the observed in some of the tet(X) genes carried by Chryseobacterium and Flavobacterium strains isolated from fish, but the produced proteins exhibited a low amino acid identity (25-27%) when compared to these synthesized by the Chilean strains. This study reports for the first time the carriage of the tet(X) gene by the Epilithonimonas genus and their detection in fish pathogenic bacteria isolated from farmed salmonids in Chile, thus limiting the use of therapies based on oxytetracycline, the antimicrobial most widely used in Chilean freshwater salmonid farming. This results suggest that pathogenic strains of the Chryseobacterium clade occurring in Chilean salmonid farms may serve as important reservoirs of tet(X) genes.
RESUMO
Antimicrobial resistance has been described in all ecosystems, including wildlife. Here we investigated the presence of methicillin-resistant and susceptible staphylococci in both colony-born and wild vervet monkeys (Chlorocebus sabaeus). Through selective isolation, PCR, MALDI-TOF, and whole-genome sequencing, methicillin-resistant and susceptible Staphylococcus spp. isolated from vervet monkeys were characterized. We obtained putatively methicillin-resistant staphylococci from 29 of the 34 nasal samples collected. Strains were identified by MALDI-TOF analysis. Staphylococcus cohnii (n = 15) was the most commonly isolated species, while nine other species were isolated one or two times. PCR analysis indicated that eight [28%] strains were mecA positive. The whole-genome sequencing [WGS] included eight methicillin-resistant strains (S. epidermidis (n = 2), S. cohnii (n = 3), S. arlettae (n = 2) and S. hominis (n = 1)), nine additional S. cohnii strains and two strains that could not be identified by MALDI-TOF, but genetically characterized as one S. cohnii and one S. warneri. Different resistance genes carried by different mobile genetic elements, mainly blaZ (n = 10) and tet(K) (n = 5) were found, while msr(A), cat, fosB, dfrG, erm(C), mph(C) and str were identified in one to three strains. Phylogenetic analysis of the S. cohnii strains based on SNPs indicated four clusters associated with colony born or wild. In addition, one singleton S. cohnii isolated did not form a separate group and clustered within other S. cohnii strains submitted to the NCBI. In this study, we demonstrated the presence of AMR and mobile genetic elements to both colony-born and wild vervet monkeys. We also identified a previously undescribed prevalence of S. cohnii in the nasal flora of these monkeys, which merits further investigation.
RESUMO
Twenty-five distinct tetracycline-resistant gram-negative bacteria recovered from four Chilean fish farms with no history of recent antibiotic use were examined for the presence of tetracycline resistance (tet) genes. Sixty percent of the isolates carried 1 of the 22 known tet genes examined. The distribution was as follows. The tet(A) gene was found in six isolates. The tet(B) gene was found in two isolates, including the first description in the genus Brevundimonas: Two isolates carried the tet(34) and tet(B) genes, including the first description of the tet(34) gene in Pseudomonas and Serratia and the first description of the tet(B) gene in Pseudomonas: The tet(H) gene was found in two isolates, which includes the first description in the genera Moraxella and Acinetobacter: One isolate carried tet(E), and one isolate carried tet(35), the first description of the gene in the genus Stenotrophomonas: Finally, one isolate carried tet(L), found for the first time in the genus Morganella: By DNA sequence analysis, the two tet(H) genes were indistinguishable from the previously sequenced tet(H) gene from Tn5706 found in Pasteurella multocida. The Acinetobacter radioresistens isolate also harbored the Tn5706-associated 1,063-bp IS element IS1597, while the Moraxella isolate carried a 1,026-bp IS-like element whose 293-amino-acid transposase protein exhibited 69% identity and 84% similarity to the transposase protein of IS1597, suggesting the presence of a novel IS element. The distribution of tet genes from the Chilean freshwater ponds was different than those that have previously been described from other geographical locations, with 40% of the isolates carrying unidentified tetracycline resistance genes.