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The overuse of antimicrobials in livestock has contributed to the emergence and selection of clinically relevant multidrug-resistant bacteria. In Brazil, there is no conclusive information on the occurrence of Escherichia coli producing extended-spectrum β-lactamase (ESβL) in cattle breeding, which is an important sector of agribusiness in this country. Herein, we investigated the presence of ESβL-positive E. coli strains in dairy cattle from a commercial farm with routine practice of therapeutic cephalosporins. Ninety-five rectal swab samples were collected from healthy dairy calves and cows under treatment with ceftiofur. Samples were screened for the presence of ESβL producers, and positive isolates were identified by MALDI-TOF, with subsequent screening for genes encoding ESβL variants by PCR and sequencing. The presence of ESβL (CTX-M-15)-producing E. coli was confirmed in calves, and lactating and dry cows. Most ESβL strains with genetic homologies ≥ 90% were grouped into two major PFGE clusters, confirming the suscessful expansion of clonally related lineages in animals from different lactating cycles, on the same property. Four representatives CTX-M-15-positive E. coli strains had their genomes sequenced, belonging to the clonal complex (CC) 23 and sequence type (ST) 90. A phylogeographical landscape of ST90 was performed revealing a global One Health linkage. Our results highlight the intestinal microbiota of dairy cattle as a hotspot for the spread of critical priority ESβL-producing E. coli and demonstrate that ST90 is an international clone genomically adapted to human and animal hosts, which deserve additional investigation to determine its zoonotic potential and impact in food chain., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Competing Interests: We declare no competing interests. This work was funded by the National Council for Scientific and Technological Development (CNPq; 304905/2022-4, 314336/2021-4, and 150712/2022-7) and the Coordination for the Improvement of Higher Education Personnel (CAPES; 88887.463868/2019-00 and Finance Code 001).

Although considered one of the most pristine ecosystems, Antarctica has been largely influenced by human activities during the last 50 years, affecting its unique biodiversity. One of the major global threats to health is the emergence of antibiotic-resistant bacteria that may be actively transferred to wildlife. We cultured and tested for antibiotic resistance in 137 cloacal and fresh fecal samples of several avian and marine mammal species from the Antarctic Peninsula, the most impacted area in Antarctica. Alarmingly, 80 % of the isolates showed antibiotic resistance, either phenotypically or genotypically. Most of the resistant bacteria, such as Enterobacteriaceae and Enterococcus species, are part of local gastrointestinal microbiota. Penguins and pinnipeds harbored a great diversity of antibiotic resistance and must be eligible as sentinels for future studies. These results show that antibiotic resistance has rapidly transferred to bacteria in Antarctic wildlife, which is a global matter of concern., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Carbapenemase-producing Citrobacter freundii has been reported as a leading cause of healthcare-associated infections. Particularly, C. freundii belonging to the sequence type (ST) 18 is considered to be an emerging nosocomial clone., Objectives: To report the genomic background and phylogenomic analysis of a multidrug-resistant NDM-1-producing C. freundii ST18 (strain CF135931) isolated from an endangered green sea turtle affected by plastic pollution in Brazil., Methods: Genomic DNA was extracted and sequenced using the Illumina NextSeq platform. De novo assembly was performed by CLC Workbench, and in silico analysis accomplished by bioinformatics tools. For phylogenomic analysis, publicly available C. freundii (txid:546) genome assemblies were retrieved from the NCBI database., Results: The genome size was calculated at 5 290 351 bp, comprising 5263 total genes, 4 rRNAs, 77 tRNAs, 11ncRNAs, and 176 pseudogenes. The strain belonged to C. freundii ST18, whereas resistome analysis predicted genes encoding resistance to β-lactams (bla NDM-1 , bla OXA-1 , bla CMY-117 , and bla TEM-1C ), aminoglycosides (aph(3'')-Ib, aadA16, aph(3')-VI, aac(6')-Ib-cr, and aph(6)-Id), quinolones (aac(6')-Ib-cr), macrolides (mph(A) and erm(B)), sulphonamides (sul1 and sul2), tetracyclines (tetA and tetD), and trimethoprim (dfrA27). The phylogenomic analysis revealed that CF135931 strain is closely related to international human-associated ST18 clones producing NDM-1., Conclusion: Genomic surveillance efforts are necessary for robust monitoring of the emergence of drug-resistant strains and WHO critical priority pathogens within a One Health framework. In this regard, this draft genome and associated data can improve understanding of dissemination dynamics of nosocomial clones of carbapenemase-producing C. freundii beyond hospital walls. In fact, the emergence of NDM-1-producing C. freundii of global ST18 in wildlife deserves considerable attention., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Stenotrophomonas maltophilia is an opportunistic human pathogen associated with nosocomial and community-acquired infections. We have conducted a microbiological and genomic surveillance study of broad-spectrum cephalosporin- and carbapenem-resistant Gram-negative bacteria colonizing wild birds inhabiting the Brazilian Amazonia. Strikingly, two S. maltophilia strains (SM79 and SM115) were identified in Plain-throated antwren (Isleria hauxwelli) passerines affected by Amazonian fragmentation and degradation. Noteworthy, SM79 and SM115 strains belonged to new sequence types (STs) ST474 and ST473, respectively, displaying resistance to broad-spectrum β-lactams, aminoglycosides and/or fluoroquinolones. In this regard, resistome analysis confirmed efflux pumps (smeABC, smeDEF, emrAB-tolC and macB), bla L1 and bla L2 , aph(3')-IIc and aac(6')-Iak, and Smqnr resistance genes. Comparative phylogenomic analysis with publicly available S. maltophilia genomes clustered ST473 and ST474 with human strains, whereas the ST474 was also grouped with S. maltophilia strains isolated from water and poultry samples. In summary, we report two novel sequence types of S. maltophilia colonizing wild Amazonian birds. The presence of opportunistic multidrug-resistant pathogens in wild birds, from remotes areas, could represent an ecological problem since these animals could easily promote long-distance dispersal of medically important antimicrobial-resistant bacteria. Therefore, while our results could provide a baseline for future epidemiological genomic studies, considering the limited information regarding S. maltophilia circulating among wild animals, additional studies are necessary to evaluate the clinical impact and degree of pathogenicity of this human opportunistic pathogen in wild birds., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Aminoglycoside antimicrobials remain valuable therapeutic options, but their effectiveness has been threatened by the production of bacterial 16S ribosomal RNA methyltransferases (16S-RMTases). In this study, we evaluated the genomic epidemiology of 16S-RMTase genes among Gram-negative bacteria circulating in the American continent. A total of 4877 16S-RMTase sequences were identified mainly in Enterobacterales and nonfermenting Gram-negative bacilli isolated from humans, animals, foods, and the environment during 1931-2023. Most of the sequences identified were found in the United States, Brazil, Canada, and Mexico, and the prevalence of 16S-RMTase genes have increased in the last five years (2018-2022). The three species most frequently carrying 16S-RMTase genes were Acinetobacter baummannii , Klebsiella pneumoniae , and Escherichia coli . The armA gene was the most prevalent, but other 16S-RMTase genes (e.g., rmtB , rmtE , and rmtF ) could be emerging backstage. More than 90% of 16S-RMTase sequences in the Americas were found in North American countries, and although the 16S-RMTase genes were less prevalent in Central and South American countries, these findings may be underestimations due to limited genomic data. Therefore, whole-genome sequence-based studies focusing on aminoglycoside resistance using a One Health approach in low- and middle-income countries should be encouraged.

The spread of carbapenemase-producing Klebsiella pneumoniae beyond hospital settings is a global critical issue within a public health and One Health perspective. Another worrisome concern is the convergence of virulence and resistance in healthcare-associated lineages of K. pneumoniae leading to unfavorable clinical outcomes. During a surveillance study of WHO critical priority pathogens circulating in an impacted urban river in São Paulo, Brazil, we isolate two hypermucoviscous and multidrug-resistant K. pneumoniae strains (PINH-4250 and PINH-4900) from two different locations near to medical centers. Genomic investigation revealed that both strains belonged to the global high-risk sequence type (ST) ST11, carrying the bla KPC-2 carbapenemase gene, besides other medically important antimicrobial resistance determinants. A broad virulome was predicted and associated with hypervirulent behavior in the Galleria mellonella infection model. Comparative phylogenomic analysis of PINH-4250 and PINH-4900 along to an international collection of publicly available genomes of K. pneumoniae ST11 revealed that both environmental strains were closely related to hospital-associated K. pneumoniae strains recovered from clinical samples between 2006 and 2018, in São Paulo city. Our findings support that healthcare-associated KPC-2-positive K. pneumoniae of ST11 clone has successfully expanded beyond hospital settings. In summary, aquatic environments can become potential sources of international clones of K. pneumoniae displaying carbapenem resistance and hypervirulent behaviors, which is a critical issue within a One Health perspective., Competing Interests: All authors declare no conflicts of interest., (© 2023 The Authors. Published by Elsevier B.V.)

Olive ridley ( Lepidochelys olivacea ) turtles migrate across tropical regions of the Atlantic, Pacific, and Indian Oceans. Worryingly, olive ridley populations have been declining substantially and is now considered a threatened species. In this regard, habitat degradation, anthropogenic pollution, and infectious diseases have been the most notorious threats for this species. We isolated a metallo-β-lactamase (NDM-1)-producing Citrobacter portucalensis from the blood sample of an infected migratory olive ridley turtle found stranded sick in the coast of Brazil. Genomic analysis of C. portucalensis confirmed a novel sequence type (ST), named ST264, and a wide resistome to broad-spectrum antibiotics. The production of NDM-1 by the strain contributed to treatment failure and death of the animal. Phylogenomic relationship with environmental and human strains from African, European and Asian countries confirmed that critical priority clones of C. portucalensis are spreading beyond hospital settings, representing an emerging ecological threat to marine ecosystems., Competing Interests: All authors declare no conflicts of interest., (© 2023 The Authors.)

Wild birds have emerged as novel reservoirs and potential spreaders of antibiotic-resistant priority pathogens, being proposed as sentinels of anthropogenic activities related to the use of antimicrobial compounds. The aim of this study was to investigate the occurrence and genomic features of extended-spectrum β-lactamase (ESBL)-producing bacteria in wild birds in South America. In this regard, we have identified two ESBL (CTX-M-55 and CTX-M-65)-positive Escherichia coli (UNB7 and GP188 strains) colonizing Creamy-bellied Thrush ( Turdus amaurochalinus ) and Variable Hawk ( Geranoaetus polyosoma ) inhabiting synanthropic and wildlife environments from Brazil and Chile, respectively. Whole-genome sequence (WGS) analysis revealed that E. coli UNB7 and GP188 belonged to the globally disseminated clone ST602, carrying a wide resistome against antibiotics (β-lactams), heavy metals (arsenic, copper, mercury), disinfectants (quaternary ammonium compounds), and pesticides (glyphosate). Additionally, E. coli UNB7 and GP188 strains harbored virulence genes encoding hemolysin E, type II and III secretion systems, increased serum survival, adhesins and siderophores. SNP-based phylogenomic analysis, using an international genome database, revealed genomic relatedness (19-363 SNP differences) of GP188 with livestock and poultry strains, and genomic relatedness (61-318 differences) of UNB7 with environmental, human and livestock strains (Table S1), whereas phylogeographical analysis confirmed successful expansion of ST602 as a global clone of One Health concern. In summary, our results support that ESBL-producing E. coli ST602 harboring a wide resistome and virulome have begun colonizing wild birds in South America, highlighting a potential new reservoir of critical priority pathogens., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 The Authors. Published by Elsevier B.V.)

Extended spectrum β-lactamase (ESBL)-producing Enterobacterales has spread rapidly around the world, reaching remote areas. In this regard, wild birds that acquire ESBL producers from anthropogenically impacted areas can become reservoirs, contributing to further dissemination of antimicrobial-resistant bacteria categorized as critical priority pathogens to remote environments, during migration seasons. We have conducted a microbiological and genomic investigation on the occurrence and features of ESBL-producing Enterobacterales in wild birds from the remote Acuy Island, in the Gulf of Corcovado, at Chilean Patagonia. Strikingly, five ESBL-producing Escherichia coli were isolated from migratory and resident gulls. Whole-genome sequencing (WGS) analysis revealed the presence of two E. coli clones belonging to international sequence types (STs) ST295 and ST388, producing CTX-M-55 and CTX-M-1 ESBLs, respectively. Moreover, E. coli carried a wide resistome and virulome associated with human and animal infections. Phylogenomic analysis of global and publicly genomes of E. coli ST388 (n = 51) and ST295 (n = 85) clustered gulls isolates along to E. coli strains isolated from the environment, companion animal and livestock in the United States of America, within or close to the migratory route of Franklin's gull, suggesting a possible trans hemispheric movement of international clones of WHO critical priority ESBL producing pathogens., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Antimicrobial resistance is an ancient natural phenomenon increasingly pressured by anthropogenic activities. Escherichia coli has been used as markers of environmental contamination and human-related activity. Seabirds may be bioindicators of clinically relevant bacterial pathogens and their antimicrobial resistance genes, including extended-spectrum-beta-lactamase (ESBL) and/or plasmid-encoded AmpC (pAmpC), in anthropized and remote areas. We evaluated cloacal swabs of 20 wild magnificent frigatebirds ( Fregata magnificens ) of the Alcatrazes Archipelago, the biggest breeding colony of magnificent frigatebirds in the southern Atlantic and a natural protected area with no history of human occupation, located in the anthropized southeastern Brazilian coast. We characterized a highly virulent multidrug-resistant ST648 (O153:H9) pandemic clone, harboring bla CTX - M -2 , bla CMY -2 , qnrB, tetB, sul1, sul2, aadA1, aac(3)-VIa and mdfA , and virulence genes characteristic of avian pathogenic (APEC) ( hlyF, iroN, iss, iutA , and ompT ) and other extraintestinal E. coli (ExPEC) ( chuA, kpsMII , and papC ). To our knowledge, this is the first report of ST648 E. coli co-producing ESBL and pAmpC in wild birds inhabiting insular environments. We suggest this potentially zoonotic and pathogenic lineage was likely acquired through indirect anthropogenic contamination of the marine environment, ingestion of contaminated seafood, or by intra and/or interspecific contact. Our findings reinforce the role of wild birds as anthropization sentinels in insular environments and the importance of wildlife surveillance studies on pathogens of critical priority classified by the World Health Organization., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Ewbank, Fuentes-Castillo, Sacristán, Esposito, Fuga, Cardoso, Godoy, Zamana, Gattamorta, Catão-Dias and Lincopan.)

Carbapenemase-producing Enterobacterales are rapidly spreading and adapting to different environments beyond hospital settings. During COVID-19 lockdown, a carbapenem-resistant NDM-1-positive Escherichia coli isolate (BA01 strain) was recovered from a pygmy sperm whale ( Kogia breviceps ), which was found stranded on the southern coast of Brazil. BA01 strain belonged to the global sequence type (ST) 162 and carried the bla NDM-1 , besides other medically important antimicrobial resistance genes. Additionally, genes associated with resistance to heavy metals, biocides, and glyphosate were also detected. Halophilic behavior (tolerance to > 10% NaCl) of BA01 strain was confirmed by tolerance tests of NaCl minimal inhibitory concentration, whereas halotolerance associated genes katE and nhaA , which encodes for catalase and Na + /H + antiporter cytoplasmic membrane, respectively, were in silico confirmed. Phylogenomics clustered BA01 with poultry- and human-associated ST162 lineages circulating in European and Asian countries. Important virulence genes, including the astA (a gene encoding an enterotoxin associated with human and animal infections) were detected, whereas in vivo experiments using the Galleria mellonella infection model confirmed the virulent behavior of the BA01 strain. WHO critical priority carbapenemase-producing pathogens in coastal water are an emerging threat that deserves the urgent need to assess the role of the aquatic environment in its global epidemiology., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Sellera, Cardoso, Fuentes-Castillo, Esposito, Sano, Fontana, Fuga, Goldberg, Seabra, Antonelli, Sandri, Kolesnikovas and Lincopan.)

Antimicrobial resistance is among the most serious public health threats of the 21st century, with great impact in terms of One Health. Among antimicrobial resistant bacteria (ARB), extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli (ESBL-EC) represent major challenges to human healthcare. Wild birds have been commonly used as environmental bioindicators of ESBL-EC. Remote locations represent a unique opportunity to evaluate the occurrence, dissemination and epidemiology of ARB in the environment. Herein we surveyed ESBL-EC in 204 cloacal swabs from six nonsynanthropic seabird species at the pristine Rocas Atoll, Brazil. We identified ESBL-EC isolates in 2.4% (5/204) of the tested seabirds, all in magnificent frigatebirds (Fregata magnificens). We isolated strains of O25b-ST131-fimH22 harboring gene bla CTX-M-8 (3 clones), ST117 harboring gene bla SHV-12 , and a novel ST11350 (clonal complex 349) harboring genes bla CTX-M-55 and fosA3. All the isolates presented Extraintestinal pathogenic E. coli (ExPEC) virulence profiles. We suggest that magnificent frigatebirds may act as "flying bridges", transporting ESBL-EC and ARGs from an anthropogenically-impacted archipelago geographically close to our pristine and remote study site. The characteristics of our isolates suggest zoonotic potential and, despite the apparent good health of all the evaluated birds, may represent a hypothetical potential threat to the avian population using the atoll. To our knowledge, this is the first description of: (1) the pandemic and public health relevant ST131-O25b harboring bla CTX-M-8 worldwide; (2) ST131-fimH22 in wild birds; and (3); fosA3 in wildlife. Our findings expand the current epidemiological knowledge regarding host and geographical distribution of ESBL-EC and ARGs in wild birds, and emphasize the disseminating characteristics and adaptability of ST131 and ST117 strains within the human-animal-interface. Herein we discuss the involvement of nonsynanthropic wild birds in the epidemiology of antimicrobial resistance and their potential as sentinels of ESBL E. coli in insular environments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Antimicrobial resistance is a critical issue that is no longer restricted to hospital settings but also represents a growing problem involving intensive animal production systems. In this study, we performed a microbiological and molecular investigation of priority pathogens carrying transferable resistance genes to critical antimicrobials in 1-day-old chickens imported from Brazil to Uruguay. Bacterial identification was performed by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, and antibiotic susceptibility was determined by Sensititre. Antimicrobial resistance genes were sought by PCR, and clonality was assessed by pulsed-field gel electrophoresis (PFGE). Four multidrug-resistant (MDR) representative strains were sequenced by an Illumina and/or Oxford Nanopore Technologies device. Twenty-eight MDR isolates were identified as Escherichia coli ( n = 14), Enterobacter cloacae ( n = 11), or Klebsiella pneumoniae ( n = 3). While resistance to oxyiminocephalosporins was due to bla CTX-M-2 , bla CTX-M-8 , bla CTX-M-15 , bla CTX-M-55 , and bla CMY-2 , plasmid-mediated quinolone resistance was associated with the qnrB19 , qnrE1 , and qnrB2 genes. Finally, resistance to aminoglycosides and fosfomycin was due to the presence of 16S rRNA methyltransferase rmtG and fosA -type genes, respectively. Short- and long-read genome sequencing of E. cloacae strain ODC_Eclo3 revealed the presence of IncQ/ rmtG (pUR-EC3.1; 7,400 bp), IncHI2A/ mcr-9.1 / bla CTX-M-2 (pUR-EC3.2, ST16 [pMLST; 408,436 bp), and IncN2/ qnrB19 / aacC3 / aph(3″)-Ib (pUR-EC3.3) resistance plasmids. Strikingly, the bla CTX-M-2 gene was carried by a novel Tn 1696 -like composite transposon designated Tn 7337 . In summary, we report that imported 1-day-old chicks can act as Trojan horses for the hidden spread of WHO critical-priority MDR pathogens harboring mcr-9 , rmtG , and extended-spectrum β-lactamase genes in poultry farms, which is a critical issue from a One Health perspective. IMPORTANCE Antimicrobial resistance is considered a significant problem for global health, including within the concept of One Health; therefore, the food chain connects human health and animal health directly. In this work, we searched for microorganisms resistant to antibiotics considered critical for human health in intestinal microbiota of 1-day-old baby chicks imported to Uruguay from Brazil. We describe genes for resistance to antibiotics whose use the WHO has indicated to "watch" or "reserve" (AWaRe classification), such as rmtG and mcr9.1 , which confer resistance to all the aminoglycosides and colistin, respectively, among other genes, and their presence in new mobile genetic elements that favor its dissemination. The sustained entry of these microorganisms evades the sanitary measures implemented by the countries and production establishments to reduce the selection of resistant microorganisms. These silently imported resistant microorganisms could explain a considerable part of the antimicrobial resistance problems found in the production stages of the system.

The emergence of mobile mcr genes mediating resistance to colistin is a critical public health issue that has hindered the treatment of serious infections caused by multidrug-resistant pathogens in humans and other animals. We report the emergence of the mcr-9.1 gene in a polymyxin-resistant extended-spectrum β-lactamase (ESBL)-producing Enterobacter kobei infecting a free-living franciscana dolphin (Pontoporia blainvillei), threatened with extinction in South America. Genomic analysis confirmed the presence of genes conferring resistance to clinically relevant β-lactam [bla CTX-M-15 , bla ACT-9 , bla OXA-1 and bla TEM-1B ], aminoglycoside [aac(3)-IIa, aadA1, aph(3'')-Ib and aph(6)-Id], trimethoprim [dfrA14], tetracycline [tetA], quinolone [aac(6')-Ib-cr and qnrB1], fosfomycin [fosA], sulphonamide [sul2] and phenicol [catA1 and catB3] antibiotics. The identification of mcr-9.1 in a CTX-M-15-producing pathogen infecting a critically endangered animal is of serious concern, which should be interpreted as a sign of further spread of critical priority pathogens and their resistance genes in threatened ecosystems., (© 2021 The Authors. Transboundary and Emerging Diseases published by Wiley-VCH GmbH.)

The dissemination of antibiotic-resistant priority pathogens beyond hospital settings is both a public health and an environmental problem. In this regard, high-risk clones exhibiting a multidrug-resistant (MDR) or extensively drug-resistant (XDR) phenotype have shown rapid adaptation at the human-animal-environment interface. In this study, we report genomic data and the virulence potential of the carbapenemase, São Paulo metallo-β-lactamase (SPM-1)-producing Pseudomonas aeruginosa strains (Pa19 and Pa151) isolated from polluted urban rivers, in Brazil. Bioinformatic analysis revealed a wide resistome to clinically relevant antibiotics (carbapenems, aminoglycosides, fosfomycin, sulfonamides, phenicols, and fluoroquinolones), biocides (quaternary ammonium compounds) and heavy metals (copper), whereas the presence of exotoxin A, alginate, quorum sensing, types II, III, and IV secretion systems, colicin, and pyocin encoding virulence genes was associated with a highly virulent behavior in the Galleria mellonella infection model. These results confirm the spread of healthcare-associated critical-priority P. aeruginosa belonging to the MDR sequence type 277 (ST277) clone beyond the hospital, highlighting that the presence of these pathogens in environmental water samples can have clinical implications for humans and other animals., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer AB declared a shared affiliation with no collaboration with several of the authors FE, HF, BF, and NL to the handling editor at the time of the review., (Copyright © 2021 Esposito, Cardoso, Fontana, Fuga, Cardenas-Arias, Moura, Fuentes-Castillo and Lincopan.)

The global dissemination of multidrug-resistant Escherichia coli lineages belonging to high- risk clones poses a significant public health threat. Herein we report the identification and genomic profiling of two multidrug-resistant E. coli strains [BL-II-03(2) and BL-II-11(3)] belonging to the O15:H1-D-ST393 (clonal complex 31) worldwide spread clone, isolated from fecal samples of indigenous peoples belonging to two different ethnic groups of remote communities of Brazilian Amazon. Genomic analysis revealed genes and mutations conferring resistance to β-lactams [bla TEM-1 ], aminoglycosides [aadA5, aph(3″)-Ib, aph(6)-Id], tetracyclines [tetB], sulfamethoxazole/trimethoprim [sul1, sul2, dfrA17], and fluoroquinolones [gyrA (D87N, S83L), parC (S80I, S57T), parE (L416F)]; and presence of IncQ1, IncFIA, and IncFIB(pB171) plasmids. On the other hand, phylogenomics of globally reported E. coli ST393 assigned E. coli strains BL-II-03(2) and BL-II-11(3) to a cluster comprising human isolates from Australia, Canada, China, Sweden, and United States of America. These results might provide valuable information for understanding dissemination of intercontinental multidrug-resistant clones in remote communities with low levels of antibiotic exposure., (Copyright © 2021 Elsevier B.V. All rights reserved.)

From 2016 to 2018, an epidemic wave of yellow fever (YF) occurred in Brazil, affecting a large number of Platyrrhini monkeys. Titi monkeys ( Callicebus spp.) were severely affected yet pathological characterizations are lacking. This study characterized epizootic YF in 43 titi monkeys ( Callicebus spp.) with respect to the microscopic lesions in liver, kidney, spleen, heart, brain, and lung, as well as the distribution of immunolabeling for YF virus antigen, and the flaviviral load in the liver. Of 43 titi monkeys examined, 18 (42%) were positive for yellow fever virus (YFV) by immunohistochemistry or reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR). Affected livers had consistent marked panlobular necrotizing hepatitis, lipidosis, and mild inflammation, with intense immunolabeling for YFV mainly in centrilobular hepatocytes (zone 1; P = .05). In the spleen, consistent findings were variable lymphoid depletion (10/11), lymphoid necrosis (lymphocytolysis; 4/11), and immunolabeling for YFV in histiocytic cells (3/16). The main finding in the kidney was multifocal acute necrosis of tubular epithelium (5/7) that was occasionally associated with intracytoplasmic immunolabeling for YFV (6/15). These data indicate that titi monkeys are susceptible to YFV infection, developing severe hepatic lesions and high viral loads, comparable to humans and Alouatta spp. Thus, Callicebus spp. may be reliable sentinels for YF surveillance.

Shiga toxin-producing Escherichia coli (STEC) are zoonotic pathogens responsible for causing food-borne diseases in humans. While South America has the highest incidence of human STEC infections, information about the genomic characteristics of the circulating strains is scarce. The aim of this study was to analyze genomic data of STEC strains isolated in South America from cattle, beef, and humans; predicting the antibiotic resistome, serotypes, sequence types (STs), clonal complexes (CCs) and phylogenomic backgrounds. A total of 130 whole genome sequences of STEC strains were analyzed, where 39.2% were isolated from cattle, 36.9% from beef, and 23.8% from humans. The ST11 was the most predicted (20.8%) and included O-:H7 (10.8%) and O157:H7 (10%) serotypes. The successful expansion of non-O157 clones such as ST16/CC29-O111:H8 and ST21/CC29-O26:H11 is highlighted, suggesting multilateral trade and travel. Virulome analyses showed that the predominant stx subtype was stx2a (54.6%); most strains carried ehaA (96.2%), iha (91.5%) and lpfA (77.7%) genes. We present genomic data that can be used to support the surveillance of STEC strains circulating at the livestock-food-human interface in South America, in order to control the spread of critical clones "from farm to table".

Objectives: The global success of carbapenem-resistant pathogens has been attributed to large plasmids carrying bla KPC genes circulating among high-risk clones. In this study, we sequenced the genome of a carbapenem-resistant Escherichia coli strain (Ec351) isolated from a human infection. Phylogenomic analysis based on single nucleotide polymorphisms (SNPs) as well as the comparative resistome and plasmidome of globally disseminated bla KPC-2 -positive E. coli strains with identical sequence type (ST) were further investigated., Methods: Total DNA was sequenced using an Illumina NextSeq 500 platform and was assembled using Unicycler. Genomic data were evaluated through bioinformatics tools available from the Center of Genomic Epidemiology and by in silico analysis., Results: Genomic analysis revealed the convergence of a wide resistome and virulome in E. coli ST648, showing a high-level phylogenetic relationship with a KPC-2-positive ST648 cluster identified in the USA and association with international clade 2. Additionally, the emergence of an IncQ1 small plasmid (pEc351) carrying bla KPC-2 (on an NTE KPC -IId element), aph(3')-VIa, and plasmid regulatory and replication genes in the pandemic clone ST648 is reported., Conclusion: Identification of a bla KPC-2 -positive IncQ1 plasmid in a high-risk E. coli clone represents rapid adaptation and expansion of these small plasmids encoding carbapenemases to novel bacterial hosts with global distribution, which deserves continued monitoring., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen that causes severe illness in humans, often associated with foodborne outbreaks. Antimicrobial resistance among foodborne E. coli has increased over the last decades becoming a public health issue. In this study, the presence and features of STEC were investigated in samples of meat, seafood, vegetables and ready-to-eat street-vended food collected in Chile, using a genomic and microbiological approach. Phenotypic and genotypic antimicrobial resistance profiles were determined, and serotype, phylogroup, sequence type (ST) and phylogenomics were predicted using bioinformatic tools. Three thousand three hundred samples collected in 2019 were screened, of which 18 were positive for STEC strains (0.5%), with stx2a (61.1%) being the predominant stx subtype. The presence of the virulence genes lpfA (100%), iha and ehaA (94.4%), and ehxA, hlyA and saa (83.3%) was confirmed among the STEC strains; the Locus of adhesion and autoaggregation (LAA) was predicted in 14 (77.8%) strains. Strains displayed resistance to colistin (100%), and intermediate resistance to enrofloxacin (11.1%) and chloramphenicol (5.6%). In this regard, mutations in the two-component regulatory system genes pmrA (S29G), pmrB (D283G) and phoP (I44L), and the presence of the qnrB19 gene were confirmed. STEC strains belonged to ST11231 (38.9%), ST297 and ST58 (16.7% each), and ST1635, ST11232, ST446, ST442 and ST54 (5.6% each), and the most frequently detected serotypes were O113:H21 (44.4%), O130:H11 and O116:H21 (16.7% each), and O174:H21 (11.1%). Strains belonging to the international ST58 showed genomic relatedness with worldwide strains from human and non-human sources. Our study reports for the first time the genomic profile of STEC strains isolated from food in Chile, highlighting the presence of international clones and sequence types commonly associated with human infections in different geographical regions, as well as the convergence of virulence and resistance in STEC lineages circulating in this country., (© 2021 Wiley-VCH GmbH.)

Serratia fonticola is a human pathogen widely found in the environment, with birds being reported as possible natural hosts. During an epidemiological and genomic surveillance study conducted to monitor the occurrence of extended-spectrum β-lactamase (ESBL)-producing Enterobacterales in South American wild birds, we identified an ESBL-positive S. fonticola in a fecal sample collected from a Hudsonian Whimbrel, during its non-breeding range on the Pacific Coast of Chile. Whole genome sequencing analysis and " in silico " modeling revealed a novel variant of the class A ESBLs FONA family, designated FONA-7, which shows 96.28% amino acid identity with FONA-6; with amino acid substitutions occurring in the signal peptide sequence (Thr22→Ser), and in the mature protein (Ser39→Asn and Thr227→Ile). This finding denotes that migratory birds can be potential vectors for the transboundary spread of ESBL-producing bacteria, creating a further theoretical risk for the origin of novel plasmid-encoded β-lactamases.

Even though antimicrobial-resistant bacteria have begun to be detected in wildlife, raising important issues related to their transmission and persistence of clinically important pathogens in the environment, little is known about the role of these bacteria on wildlife health, especially on endangered species. The Brazilian merganser (Mergus octosetaceus) is one of the most threatened waterfowl in the world, classified as Critically Endangered by the International Union for Conservation of Nature. In 2019, a fatal case of sepsis was diagnosed in an 8-day-old Brazilian merganser inhabiting a zoological park. At necropsy, major gross lesions were pulmonary and hepatic congestion. Using microbiologic and genomic methods, we identified a multidrug-resistant (MDR) extended-spectrum β-lactamase (ESBL) CTX-M-8-producing Escherichia coli (designed as PMPU strain) belonging to the international clone ST58, in coelomic cavity, oesophagus, lungs, small intestine and cloaca samples. PMPU strain harboured a broad resistome against antibiotics (cephalosporins, tetracyclines, aminoglycosides, sulphonamides, trimethoprim and quinolones), domestic/hospital disinfectants and heavy metals (arsenic, mercury, lead, copper and silver). Additionally, the virulence of E. coli PMPU strain was confirmed using a wax moth (Galleria mellonella) infection model, and it was supported by the presence of virulence genes encoding toxins, adherence factors, invasins and iron acquisition systems. Broad resistome and virulome of PMPU contributed to therapeutic failure and death of the animal. In brief, we report for the first time a fatal colibacillosis by MDR ESBL-producing E. coli in critically endangered Brazilian merganser, highlighting that besides colonization, critical priority pathogens are threatening wildlife. E. coli ST58 clone has been previously reported in humans, food-producing animals, wildlife and environment, supporting broad adaptation and persistence at human-animal-environment interface., (© 2020 The Authors. Transboundary and Emerging Diseases published by Blackwell Verlag GmbH.)

The global spread of antibiotic-resistant bacteria and their resistance genes is a critical issue that is no longer restricted to hospital settings, but also represents a growing problem involving environmental and food safety. In this study, we have performed a microbiological and genomic investigation of critical priority pathogens resistant to broad-spectrum cephalosporins and showing endophytic lifestyles in fresh vegetables sold in a country with high endemicity of extended-spectrum β-lactamases (ESBLs). We report the isolation of international high-risk clones of CTX-M-15-producing Escherichia coli , belonging to clonal complexes CC38 and CC648, and Klebsiella pneumoniae of complex CC307 from macerated tissue of surface-sterilized leaves of spinach, cabbage, arugula, and lettuce. Regardless of species, all ESBL-positive isolates were able to endophytically colonize common bean ( Phaseolus vulgaris ) seedlings, showed resistance to acid pH, and had a multidrug-resistant (MDR) profile to clinically relevant antibiotics (i.e., broad-spectrum cephalosporins, aminoglycosides, and fluoroquinolones). Genomic analysis of CTX-M-producing endophytic Enterobacterales revealed a wide resistome (antibiotics, biocides, disinfectants, and pesticides) and virulome, and genes for endophytic fitness and for withstanding acidic conditions. Transferable IncFIB and IncHI2A plasmids carried bla CTX-M-15 genes and, additionally, an IncFIB plasmid (named pKP301cro) also harbored genes encoding resistance to heavy metals. These data support the hypothesis that fresh vegetables marketed for consumption can act as a figurative Trojan horse for the hidden spread of international clones of critical WHO priority pathogens producing ESBLs, and/or their resistance genes, to humans and other animals, which is a critical issue within a food safety and broader public and environmental health perspective. IMPORTANCE Extended-spectrum β-lactamases (ESBL)-producing Enterobacterales are a leading cause of human and animal infections, being classified as critical priority pathogens by the World Health Organization. Epidemiological studies have shown that spread of ESBL-producing bacteria is not a problem restricted to hospitals, but also represents a growing problem involving environmental and food safety. In this regard, CTX-M-type β-lactamases have become the most widely distributed and clinically relevant ESBLs worldwide. Here, we have investigated the occurrence and genomic features of ESBL-producing Enterobacterales in surface-sterilized fresh vegetables. We have uncovered that international high-risk clones of CTX-M-15-producing Escherichia coli and Klebsiella pneumoniae harboring a wide resistome and virulome, carry additional genes for endophytic fitness and resistance to acidic conditions. Furthermore, we have demonstrated that these CTX-M-15-positive isolates are able to endophytically colonize plant tissues. Therefore, we believe that fresh vegetables can act as a figurative Trojan horse for the hidden spread of critical priority pathogens exhibiting endophytic lifestyles., (Copyright © 2021 Lopes et al.)

Knowledge of infectious diseases in wildlife provides important information for preventing potential outbreaks of zoonotic diseases. Adiaspiromycosis is a neglected human disease caused by dimorphic Onygenales fungi. The disease is produced by the inflammatory response against growing adiaspores, leading to granulomatous pneumonia. In humans, adiaspiromycosis is relevant in immunosuppressed patients. In animals, it is associated with pneumonia in fossorial species. Given the potential role of armadillos in the epidemiology of adiaspiromycosis, in this study, we sought to investigate the occurrence and pathological features of adiaspiromycosis in roadkilled armadillos. In total, 54 armadillo carcasses were suitable for postmortem pathologic examinations between February 2017 and 2020. Adiaspores, associated with granulomatous lesions, were observed in ten six-banded (Euphractus sexcinctus) and two southern naked-tailed armadillos (Cabassous unicinctus). A previously uncharacterized Onygenales species was molecularly identified in two E. sexcinctus. In summary, herein we report 12 cases of pulmonary adiaspiromycosis (PA) in two species of free-living armadillos in Brazil. Both, the morphology of the fungus, as well as the histopathological findings (granulomatous inflammatory response to adiaspores) are consistent with PA; however, as the molecular identification differs from the reported species, the potential impact of this fungus for human PA is unknown, and we cannot rule out its impact on public health.

Parasitological studies of the Franklin's gull, Leucophaeus pipixcan, are scarce, and knowledge about its endoparasites is quite limited. In order to describe its parasitic community, a total of 60 Franklin's gulls were captured in the coastal area in central Chile, using modified Bal-chatri traps. Ectoparasites were collected from all 60 live individuals through inspection of their plumage, while 30 were examined for endoparasites by standard parasitological necropsy. The prevalence of ectoparasites was 78.3%, including the feather mite Zachvatkinia larica (43.3%) and four species of lice: Actornithophilus piceus lari (15.0%), Austromenopon transversum (6.7%), Quadraceps punctatus (10.0%) and Saemundssonia lari (46.7%). Some 25 of 30 (83.3%) of birds necropsied were parasitized with the following helminths: Aporchis sp. (6.7%), Tetrabothrius cylindraceus (56.7%), Cyclophyllidea gen. sp. (3.3%), Profilicollis altmani (56.7%), Eucoleus contortus (10.0%), Cosmocephalus obvelatus (13.3%), Paracuaria adunca (10.0%), Stegophorus sp. (3.3%) and Tetrameres skrjabini (3.3%). To our knowledge, with the exception of P. altmani, these helminths are reported for first time in the Franklin's gull.

Non-O157 Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen that causes bloody diarrhea and hemolytic-uremic syndrome in humans, and a major cause of foodborne disease. Despite antibiotic treatment of STEC infections in humans is not recommended, the presence of antimicrobial-resistant bacteria in animals and food constitutes a risk to public health, as the pool of genes from which pathogenic bacteria can acquire antibiotic resistance has increased. Additionally, in Chile there is no information on the antimicrobial resistance of this pathogen in livestock. Thus, the aim of this study was to characterize the phenotypic and genotypic antimicrobial resistance of STEC strains isolated from cattle and swine in the Metropolitan region, Chile, to contribute relevant data to antimicrobial resistance surveillance programs at national and international level. We assessed the minimal inhibitory concentration of 18 antimicrobials, and the distribution of 12 antimicrobial resistance genes and class 1 and 2 integrons in 54 STEC strains. All strains were phenotypically resistant to at least one antimicrobial drug, with a 100% of resistance to cefalexin, followed by colistin (81.5%), chloramphenicol (14.8%), ampicillin and enrofloxacin (5.6% each), doxycycline (3.7%), and cefovecin (1.9%). Most detected antibiotic resistance genes were dfr A1 and tet A (100%), followed by tet B (94.4%), bla TEM-1 (90.7%), aac(6)-Ib (88.9%), bla AmpC (81.5%), cat 1 (61.1%), and aac(3)-IIa (11.1%). Integrons were detected only in strains of swine origin. Therefore, this study provides further evidence that non-O157 STEC strains present in livestock in the Metropolitan region of Chile exhibit phenotypic and genotypic resistance against antimicrobials that are critical for human and veterinary medicine, representing a major threat for public health. Additionally, these strains could have a competitive advantage in the presence of antimicrobial selective pressure, leading to an increase in food contamination. This study highlights the need for coordinated local and global actions regarding the use of antimicrobials in animal food production., (Copyright © 2020 Galarce, Sánchez, Fuenzalida, Ramos, Escobar, Lapierre, Paredes-Osses, Arriagada, Alegría-Morán, Lincopán, Fuentes-Castillo, Vera-Leiva, González-Rocha, Bello-Toledo and Borie.)

Comparative studies of parasites in sympatric bird species have been generally scarce. Parasitic infection/transmission can be spread in a number of ways that suggests possible direct and indirect, horizontal transmission between avian hosts. In order to determine whether two sympatric icterids from Central and Southern Chile share their parasite fauna (ecto- and endoparasites), we examined parasites of 27 Shiny Cowbirds, Molothrus bonariensis, and 28 Austral Blackbirds, Curaeus curaeus, including individuals captured in the wild and carcasses. We found that Shiny Cowbirds were infected with the chewing lice Brueelia bonariensis, Philopterus sp. 1, the feather mites Amerodectes molothrus, Proctophyllodes spp. (species 1 and 2), and the helminths Mediorhynchus papillosus, Plagiorhynchus sp., Dispharynx nasuta and Tetrameres paucispina, while Austral Blackbirds had the chewing lice Myrsidea sp., Philopterus sp. 2, the feather mites Proctophyllodes sp. 3, Amerodectes sp., and three helminths: Anonchotaenia sp., Capillaria sp. and M. papillosus. The flea Dasypsyllus (Neornipsyllus) cteniopus was found only on the Austral Blackbird. The only parasite species shared by both icterids was the acanthocephalan M. papillosus, possibly due to their feeding on the same intermediate insect hosts. With the exception of B. bonariensis and Philopterus sp. 1 found on the Shiny Cowbird, all species reported in this study represent new parasite-host associations and new records of parasite diversity in Chile.

Critical priority pathogens have globally disseminated beyond clinical settings, thereby threatening wildlife. Andean Condors (Vultur gryphus) are essential for ecosystem health and functioning, but their populations are globally near threatened and declining due to anthropogenic activities. During a microbiological and genomic surveillance study of critical priority antibiotic-resistant pathogens, we identified pandemic lineages of multidrug-resistant extended-spectrum β-lactamase (ESBL)-producing Escherichia coli colonizing Andean Condors admitted at two wildlife rehabilitation centres in South America. Genomic analysis revealed the presence of genes encoding resistance to hospital and healthcare agents among international E. coli clones belonging to sequence types (STs) ST162, ST602, ST1196 and ST1485. In this regard, the resistome included genes conferring resistance to clinically important cephalosporins (i.e., CTX-M-14, CTX-M-55 and CTX-M-65 ESBL genes), heavy metals (arsenic, mercury, lead, cadmium, copper, silver), pesticides (glyphosate) and domestic/hospital disinfectants, suggesting a link with anthropogenic environmental pollution. On the other hand, the presence of virulence factors, including the astA gene associated with outbreak of childhood diarrhoea and extra-intestinal disease in animals, was identified, whereas virulent behaviour was confirmed using the Galleria mellonella infection model. E. coli ST162, ST602, ST1196 and ST1485 have been previously identified in humans and food-producing animals worldwide, indicating that a wide resistome could contribute to rapid adaptation and dissemination of these clones at the human-animal-environment interface. Therefore, these results highlight that Andean Condors have been colonized by critical priority pathogens, becoming potential environmental reservoirs and/or vectors for dissemination of virulent and antimicrobial-resistant bacteria and/or their genes, in associated ecosystems and wildlife., (© 2020 John Wiley & Sons Ltd.)

Out of the 20 recognized species of armadillos in the world, 11 are found in Brazil, and five of them are found in Pantanal, one of the world's largest wetlands. Beef cattle ( Bos taurus ) farming is the main economic activity in this region, which promotes intense wildlife-livestock contact and increases the likelihood of pathogen exposure, including to agents with zoonotic and economic relevance. Previous studies demonstrated that several wildlife species in Pantanal have been exposed to Brucella abortus and Leptospira spp.; however, little is known regarding the exposure and/or prevalence of zoonotic pathogens in armadillos. We used conventional PCR, the rose Bengal test (RBT), and the microscopic agglutination test (MAT) to investigate the exposure to and infection by Brucella spp. and Leptospira spp. using blood samples from four species of armadillos: nine-banded armadillo ( Dasypus novemcinctus , n =2), southern naked-tailed armadillo ( Cabassous unicinctus , n =8), yellow armadillo ( Euphractus sexcinctus , n =16), and giant armadillo ( Priodontes maximus , n =22), captured in Nhecolândia, Pantanal, Brazil. Samples were PCR- and RBT-negative for Brucella spp. infection and exposure. However, MAT revealed a Leptospira spp. seroprevalence of 31% (5/16; 95% confidence interval [CI]=0.11-0.58) in yellow armadillo and 18% (4/22; 95% CI=0.05-0.40) in giant armadillo specimens to serogroups Autumnalis, Cynopteri, and Pomona, with titers ranging from 200 to 1,600. Our results contribute to the understanding of zoonotic pathogens in armadillos in Pantanal and reinforce the importance of wildlife health surveillance in this area.

Extended-spectrum β-lactamases (ESBLs)-producing Enterobacteriaceae have been classified as critical priority pathogens by the World Health Organization (WHO). We have conducted a microbiological and genomic surveillance study, in order to investigate the occurrence and features of antibiotic-resistant bacteria in wild birds admitted to a wildlife rescue and rehabilitation centre in Chile. This study reports for the first time the occurrence of highly virulent ESBL-producing Escherichia coli and Salmonella enterica serovar Infantis in wild owls inhabiting the Southern Cone of America. Genomic analysis revealed a wide resistome (for antibiotics, heavy metals and disinfectants) among international lineages of E. coli belonging to ST345 and ST2705, and S. Infantis ST32, producing CTX-M-8 or CTX-M-65 ESBLs. On the other hand, wide virulome was associated with a highly virulent behaviour in the Galleria mellonella infection model. Worryingly, all these lineages have been previously reported in humans, supporting that wide resistome and virulome could be contributing to rapid adaptation and dissemination of these clones at the human-animal-environment interface. In summary, wild owls can constitute environmental reservoirs of international clones of ESBL (CTX-M)-producing E. coli and S. Infantis carrying a wide resistome and virulome, in the Southern Cone of America, with potential risks to human, animal and environmental health., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In humans, emerging infectious diseases are mostly zoonoses with ticks playing an important role as vectors. Tick-borne relapsing fever Borrelia and spotted fever Rickettsia occur in endemic foci along tropical and subtropical regions of the globe. However, both are widely neglected etiologic agents. In this study, we performed molecular analyses in order to assess the presence of Borrelia and Rickettsia DNA in ticks infesting small-mammals within a National Reserve located in the Andes Mountains, central Chile. While hard ticks were negative for the presence of both agents, sequences of four rickettsial (gltA, htrA, ompA, ompB) and two borrelial (16S rRNA and flaB) genes were obtained from larvae of an Ornithodoros sp. morphologically related with Ornithodoros atacamensis. Phylogenetic analyses indicated that the detected Borrelia and Rickettsia spp. belong to the relapsing fever and spotted fever groups, respectively. Moreover, the agents formed monophyletic clades with Rickettsia amblyommatis and "Candidatus Borrelia johnsonii." As positive ticks parasitize rodents within a highly visited National Reserve where outdoor activities are of common practice, the risk for human parasitism should not be discarded.

Despite being a bird with a broad and extensive distribution in Chile, the black-chinned siskin, Spinus barbatus Molina, 1782 is not well studied in relation to its parasites. This paper aims to describe the ectoparasite fauna of S. barbatus in central and southern Chile. A total of 125 individuals caught with mist nets were examined alive; a total of 22 parasites were found dead and were exposed to parasit autopsy. The extracted parasites were preserved in 70% alcohol for subsequent mounting and identification. Ectoparasites were found in 56 black-chinned siskins (38%); 48 of them (33%) had 870 mites - 680 feather mites (Astigmata: Analgoidea) were identified as Proctophyllodes spini, 167 as Knemidokoptes jamaicensis, 19 as Strelkoviacarus critesi, and one as Analges passerinus. Moreover, three mites were chiggers belonging to the tribe Schoengastiini (Prostigmata: Trombiculidae). In 21 birds (14%), 54 lice were found, 21 of which were identified as Philopterus roehreri, 18 as Myrsidea serini, and 15 as Ricinus carolynae. Endoparasites were not found in the necropsied individuals. All of the parasites that were found represent new records for Chile, and they also serve as new records of host-parasite associations for S. barbatus.