First Isolation of Methicillin-Resistant Livestock-Associated Staphylococcus aureus CC398 and CC1 in Intensive Pig Production Farms in Argentina.

Since the mid-2000s, livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) has been identified among pigs worldwide, CC398 being the most relevant LA-MRSA clone. In the present work, nasal swabs were taken from healthy pigs of different age categories (25 to 154 days) from 2019 to 2021 in four intensive farms located in three provinces of Argentina. The aim of the present study was to characterize the first LA-MRSA isolates that colonized healthy fattening pigs in Argentina in terms of their resistance phenotype and genotype and to know the circulating clones in the country. Antimicrobial susceptibility, presence of the mecA gene and PCR screening of CC398 were evaluated in all the isolates. They were resistant to cefoxitin, penicillin, tetracycline, chloramphenicol and ciprofloxacin but susceptible to nitrofurantoin, rifampicin, vancomycin and linezolid. Furthermore, 79% were resistant to clindamycin and lincomycin, 68% to erythromycin, 58% to gentamicin and 37% to trimethoprim/sulfamethoxazole. All the isolates were multidrug resistant. The clonal relation was assessed by SmaI-PFGE (pulsed-field gel electrophoresis) and a representative isolate of each PFGE type was whole genome sequenced by Illumina. MLST (multilocus sequence typing), resistance and virulence genes and SCCmec typing were performed on sequenced isolates. The isolates were differentiated in three clonal types by PFGE, and they belonged to sequence-type ST398 (58%) and ST9, CC1 (42%) by MLST. SCCmec typeV and several resistance genes detected showed complete correlation with resistance phenotypes. The present study revealed that LA-MRSA colonizing healthy pigs in Argentina belongs to CC398 and CC1, two MRSA lineages frequently associated to pigs in other countries.

Genomic Features of Antimicrobial Resistance in Staphylococcus pseudintermedius Isolated from Dogs with Pyoderma in Argentina and the United States: A Comparative Study.

Staphylococcus pseudintermedius is the most common opportunistic pathogen in dogs and methicillin resistance (MRSP) has been identified as an emerging problem in canine pyoderma. Here, we evaluated the antimicrobial resistance (AMR) features and phylogeny of S. pseudintermedius isolated from canine pyoderma cases in Argentina (n = 29) and the United States (n = 29). 62% of isolates showed multi-drug resistance. The AMR genes found: mecA, blaZ, ermB, dfrG, catA, tetM, aac(6')-aph(2″), in addition to tetK and lnuA (only found in U.S. isolates). Two point mutations were detected: grlA(S80I)-gyrA(S84L), and grlA(D84N)-gyrA(S84L) in one U.S. isolate. A mutation in rpoB (H481N) was found in two isolates from Argentina. SCCmec type III, SCCmec type V, ΨSCCmec57395 were identified in the Argentinian isolates; and SCCmec type III, SCCmec type IVg, SCCmec type V, and SCCmec type VII variant in the U.S. cohort. Sequence type (ST) ST71 belonging to a dominant clone was found in isolates from both countries, and ST45 only in Argentinian isolates. This is the first study to comparatively analyze the population structure of canine pyoderma-associated S. pseudintermedius isolates in Argentina and in the U.S. It is important to maintain surveillance on S. pseudintermedius populations to monitor AMR and gain further understanding of its evolution and dissemination.

First report of Staphylococcus pseudintermedius ST71-SCCmec III and ST45-ΨSCCmec57395 from canine pyoderma in Argentina.

Staphylococcus pseudintermedius is an opportunistic pathogen commonly associated with skin infections in dogs. Twenty-three methicillin-resistant S. pseudintermedius (MRSP) isolated in Argentina from dogs with pyoderma were analyzed using whole genome sequencing (WGS) and classified into sequence types (ST) by multilocus sequence typing (MLST) and staphylococcal chromosome cassette mec (SCCmec) types.Based on the WGS analysis, MLST, and SCCmec type results, we report for the first time in Argentina two MRSP strains, one each, belonging to ST71-SCCmec III and ST45-ΨSCCmec57395 from dogs with pyoderma. We also identified seven isolates with ST339, which had been previously reported in only two isolates in Argentina. Additionally, we identified ten MRSP isolates harboring variants of the SCCmec V found in S. aureus, seven SCCmec V (5C2&5) with two ccrC1 recombinases, and three SCCmec V (5C2) with one ccrC1 recombinase.Our findings provide important insights into the evolution and geographic spread of these hypervirulent dominant clones that threaten the health of our companion animals and represent a significant risk for zoonotic infections.

Gulls as carriers of antimicrobial resistance genes in different biogeographical areas of South America.

The aim of this communication was to establish if Enterobacterales associated with gulls in Argentina harbored antimicrobial resistance (AMR) genes. We analyzed cloacal swabs in two contrasting areas: Ensenada, Buenos Aires province (26 Larus dominicanus and 22 Chroicocephalus maculipennis) and Puerto Madryn, Chubut province (20 L. dominicanus). In Ensenada, bla CTX-M and mcr-1 genes, were isolated from both gull species, whereas in the Puerto Madryn, only bla CTX-M gene was found. We report for the first time C. maculipennis as carrier of AMR. The finding of AMR in wildlife constitutes a useful tool in evaluating the anthropogenic impact on environmental health.

Identification and molecular epidemiology of methicillin resistant Staphylococcus pseudintermedius strains isolated from canine clinical samples in Argentina.

BACKGROUND: Staphylococcus pseudintermedius is the leading cause of pyoderma in dogs and the frequent use of antimicrobial treatment is associated to the development of resistance to nearly all classes of antibiotics. Despite S. pseudintermedius significance, our understanding of the molecular mechanism of ß-lactam resistance and its genetic diversity remains limited. We aimed to: i) determine the phenotypic resistance profile of methicillin resistant Staphylococcus pseudintermedius (MRSP) isolated from infected dogs in three different veterinary hospitals in Buenos Aires, Argentina; ii) identify the SCCmec elements and resistance genes; and iii) analyze the clonal relationship between isolates and in regard of dominant lineages found in the world. RESULTS: In addition to the differential levels of ß-lactam resistance, MRSP isolates (n = 10) showed resistance to 5-6 families of antibiotics, and were therefore categorized as multidrug-resistant. All the isolates were variant of SCCmec V homologous to S. aureus; additional SCCmecFinder analysis classified five of the genomes as SCCmec type V (5C2&5) with mecA (encodes for PBP2a), mecRI and mecI and all the genes closely related to the reference SCCmec type V S. aureus TSGH17 strain. In the remaining five strains, mecA was present, although other genes associated with SCCmec V including mecR1 and mecI were missing. PBP2a was inducible in low level resistance strains (MRSP 8151), and constitutively expressed in MRSP 8150, suggesting different mecA regulatory mechanisms. MRSP isolates showed significant genetic diversity: eight PFGE clonal types and six multilocus-sequence typing (MLST) sequence types (STs) (339, 649, 919, 920, 921 and 922), including four new STs genetically distinct from STs reported in other geographic areas. Comparative genomics and phylogenetic analyses of the MRSP showed a correlation between the genetic content and the phenotypes, and established the genetic relationship between the isolates. CONCLUSIONS: MRSP could be a threat to animal health due to it concerning level of antimicrobial resistance. Our study highlights genetic and epidemiological aspects of multidrug-resistant MRSP strains from Argentina showing high degree of correlation between the resistance genes and the phenotype of the isolates and, furthermore, they appeared evolutionary closer to major worldwide reported ST68 and ST71.

Multidrug-resistant Escherichia coli harbouring mcr-1 and blaCTX-M genes isolated from swine in Argentina.

OBJECTIVES: Multidrug-resistant Escherichia coli isolates recovered from food-producing animals are a global public-health concern, especially those with transferable mechanisms of antimicrobial resistance such as extended-spectrum ß-lactamase (ESBL) and mcr-1 genes. Here we report for the first time E. coli recovered from diarrhoeic and healthy pigs harbouring blaCTX-M and/or mcr-1 from Argentinean farms. METHODS: During 2017, a total of 34 E. coli were recovered from 31 faecal samples from diarrhoeic piglets and healthy fattening pigs from five pig farms in three Argentinean provinces. Antimicrobial susceptibility was evaluated by agar diffusion and resistance genes were identified by PCR. Multiplex PCR was applied to screen for ST69, ST73, ST95 and ST131 clones. Genetic relationships were evaluated by XbaI-PFGE. RESULTS: A high diversity of resistance profiles was observed (20 profiles among 34 isolates), and 71% of isolates were multidrug-resistant. Resistance to third-generation cephalosporins (3GCs) was observed in 28 isolates and was associated with blaCTX-M (24), blaCMY (3) and blaPER-2 (1) genes. blaCTX-M alleles were grouped by specific PCR as follow: 17 blaCTX-M-8/25; 4 blaCTX-M-1/15; 2 blaCTX-M-2; and 1 blaCTX-M-9/14. Twelve isolates were positive for mcr-1, of which six were also resistant to 3GCs and were positive for blaCTX-M-8/25 (4), blaCTX-M-1/15 (1) or blaCMY (1). High genetic diversity was observed, discriminating 29 profiles. One ST131 and two ST95 human-associated clones were detected. CONCLUSION: Here we describe E. coli isolates recovered from diarrhoeic piglets and healthy fattening pigs harbouring ESBL and/or mcr-1 genes. 3GC resistance was mainly associated with CTX-M, in particular with blaCTX-M-8/25 alleles.

kMucormicosys due to Saksenaea vasiformis in a dog.

A 2-year-old female Border collie was examined for dermatitis with a partial alopecic zone around her left front member. Six months later the lesion became swollen, alopecic with ulcerated areas. Microscopy analysis of samples showed numerous non-septate, branching, thin-walled and irregular shaped hyphal elements. Fungal cultures and molecular studies identified Saksenaea vasiformis. Treatments with griseofulvin, itraconazole and surgical debridement were used, however, fourteen months later the dog was euthanatized because of the unfavorable clinical outcome.

[Antimicrobial resistance and molecular epidemiology of Staphylococcus pseudintermedius strains isolated from dog clinical samples]. / Resistencia antimicrobiana y epidemiología molecular de aislamientos de Staphylococcus pseudintermedius de muestras clínicas de caninos.

Twenty-eight strains isolated from dog clinical samples identified as Staphylococcus pseudintermedius by mass spectrometry (MALDI-TOF) were studied to assess antimicrobial susceptibility by the diffusion method and clonal relationship by pulsed field gel electrophoresis (PFGE). Methicillin resistance (3/28 isolates; 10,7%) was evaluated by mecA PCR. Fifteen strains (53.6%) were resistant to at least one of the antibiotics tested, and eleven of them (39.3%) showed multiple resistance (3 or more antimicrobial families). Eleven isolates (39.3%) were resistant to erythromycin due to the presence of ribosomal methylase ermB, whereas clindamycin inducible resistance was not detected. Twenty-seven (27) clonal types were differentiated by PFGE, suggesting high clonal diversity. We emphasize that the finding of multiresistant S. psedintermedius strains is an emerging problem to be considered in veterinary diagnostic laboratory treatment of canine infections and in public health settings.

Resistencia antimicrobiana y epidemiología molecular de aislamientos de Staphylococcus pseudintermedius de muestras clínicas de caninos / Antimicrobial resistance and molecular epidemiology of Staphylococcus pseudintermedius strains isolated from dog clinical samples

Se estudiaron 28 aislamientos obtenidos de muestras clínicas de perros e identificados por espectrometría de masas (MALDI-TOF) como Staphylococcus pseudintermedius; el objetivo fue evaluar la sensibilidad a los antimicrobianos por el método de difusión y establecer la relación clonal entre aislamientos por electroforesis en campo pulsado (PFGE). La resistencia a meticilina se evaluó mediante PCR por amplificación del gen mecA y se observó en 3/28 aislamientos (10,7 %). Quince aislamientos (53,6 %) presentaron resistencia a alguno de los antibióticos ensayados y 11 de ellos (39,3 %) presentaron resistencia múltiple (resistencia a 3 o más familias de antibióticos). Once aislamientos (39,3 %) presentaron resistencia a eritromicina, debido a la presencia de metilasa ribosomal ermB, y no se detectó resistencia inducible a clindamicina. Por PFGE se pudieron diferenciar 27 tipos clonales, lo cual demuestra gran diversidad clonal. Se destaca el hallazgo de aislamientos de S. pseudintermedius multirresistentes como una eventual problemática a considerar en el diagnóstico veterinario de laboratorio, el tratamiento de las infecciones caninas y el ámbito de la salud pública.

Twenty-eight strains isolated from dog clinical samples identified as Staphylococcus pseudintermedius by mass spectrometry (MALDI-TOF) were studied to assess antimicrobial susceptibility by the diffusion method and clonal relationship by pulsed field gel electrophoresis (PFGE). Methicillin resistance (3/28 isolates; 10,7 %) was evaluated by mecA PCR. Fifteen strains (53.6 %) were resistant to at least one of the antibiotics tested, and eleven of them (39.3 %) showed multiple resistance (3 or more antimicrobial families). Eleven isolates (39.3 %) were resistant to erythromycin due to the presence of ribosomal methylase ermB, whereas clindamycin inducible resistance was not detected. Twenty-seven (27) clonal types were differentiated by PFGE, suggesting high clonal diversity. We emphasize that the finding of multiresistant S. psedintermedius strains is an emerging problem to be considered in veterinary diagnostic laboratory treatment of canine infections and in public health settings.

Wild-type minimal inhibitory concentration distributions in bacteria of animal origin in Argentina.

The aim of this study was to determine the antimicrobial resistance profiles of indicator bacteria isolated from domestic animal feces. Minimal inhibitory concentration (MIC) was determined by agar dilution. Interpretative criteria on the basis of wild-type MIC distributions and epidemiological cutoff values (ECOFF or ECV) were used according to the 'European Committee on Antimicrobial Susceptibility Testing' (EUCAST) data. Results from 237 isolates of Escherichia coli showed reduced susceptibility for ampicillin, streptomycin and tetracycline, the antimicrobials commonly used in intensive breeding of pigs and hens. Regarding all the species of the genus Enterococcus spp., there are only ECOFF or ECV for vancomycin. Of the 173 Enterococcus spp. isolated, only one showed reduced susceptibility to vancomycin and was classified as 'non-wild-type' (NWT) population. This is the first report in Argentina showing data of epidemiological cutoff values in animal bacteria.

Distribución de la concentración inhibitoria mínima y puntos de corte "wild-type" en bacterias de origen animal en Argentina / Wild-typeminimal inhibitory concentration distributions in bacteria of animal origin in Argentina

El objetivo de este estudio fue determinar los patrones de resistencia antimicrobiana en bacterias indicadoras aisladas de muestras fecales de animales domésticos. La concentración inhibitoria mínima (CIM) fue determinada por el método de dilución en agar. El criterio de interpretación usado se basó en la distribución de la CIM y el punto de corte epidemiológico (ECOFF o ECV) de acuerdo con los datos del European Committee on Antimicrobial Susceptibility Testing (EUCAST). Los resultados obtenidos de 237 aislamientos de Escherichia coli mostraron sensibilidad reducida a ampicilina, estreptomicina y tetraciclina, antimicrobianos comúnmente usados en porcinos y aves de explotación intensiva. Con respecto a todas las especies del género Enterococcus spp., solo existe ECOFF o ECV para la vancomicina. De los 173 Enterococcus spp. aislados, sólo uno presentó sensibilidad reducida a dicho agente y fue categorizado como población 'non-wild-type' (NWT). Este es el primer informe en Argentina que presenta datos de puntos de corte epidemiológico en bacterias animales

The aim of this study was to determine the antimicrobial resistance profiles of indicator bacteria isolated from domestic animal feces. Minimal inhibitory concentration (MIC) was determined by agar dilution. Interpretative criteria on the basis of wild-type MIC distributions and epidemiological cutoff values (ECOFF or ECV) were used according to the 'European Committee on Antimicrobial Susceptibility Testing' (EUCAST) data. Results from 237 isolates of Escherichia coli showed reduced susceptibility for ampicillin, streptomycin and tetracycline, the antimicrobials commonly used in intensive breeding of pigs and hens. Regarding all the species of the genus Enterococcus spp., there are only ECOFF or ECV for vancomycin. Of the 173 Enterococcus spp. isolated, only one showed reduced susceptibility to vancomycin and was classifi ed as 'non-wild-type' (NWT) population. This is the fi rst report in Argentina showing data of epidemiological cutoff values in animal bacteria

Wild-type minimal inhibitory concentration distributions in bacteria of animal origin in Argentina. / Wild-type minimal inhibitory concentration distributions in bacteria of animal origin in Argentina.

The aim of this study was to determine the antimicrobial resistance profiles of indicator bacteria isolated from domestic animal feces. Minimal inhibitory concentration (MIC) was determined by agar dilution. Interpretative criteria on the basis of wild-type MIC distributions and epidemiological cutoff values (ECOFF or ECV) were used according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) data. Results from 237 isolates of Escherichia coli showed reduced susceptibility for ampicillin, streptomycin and tetracycline, the antimicrobials commonly used in intensive breeding of pigs and hens. Regarding all the species of the genus Enterococcus spp., there are only ECOFF or ECV for vancomycin. Of the 173 Enterococcus spp. isolated, only one showed reduced susceptibility to vancomycin and was classified as non-wild-type (NWT) population. This is the first report in Argentina showing data of epidemiological cutoff values in animal bacteria.

Thermotolerant Campylobacters in domestic animals in a defined population in Buenos Aires, Argentina.

We assessed the prevalence of Campylobacter jejuni in animals in a region of unsatisfied basic needs in the city of Buenos Aires and studied a few risk factors. First we conducted a census to identify all dwellings having pet animals (dogs, cats, and birds). Fecal samples were then taken for isolation and identification of strains. We observed 17% prevalence for dogs (95% CI: 13, 22), 16% for cats (95% CI: 8, 27) and 19% for birds (95% CI: 5, 42). In dogs, the highest prevalences were found in summer and in animals <1 year old; in cats, in autumn and those aged 3-5 years. Strains were identified as C. jejuni biotype II in 70% of isolates. In the population described here, dogs, cats and birds kept in households were potential sources of human Campylobacter infections.