Staphylococcus resistentes a la meticilina en el marco de «Una Salud»: un viejo conocido en medicina humana vigente en la medicina veterinaria

El género Staphylococcus actualmente comprende 81 especies y subespecies, la mayoría de las cuales son comensales o patógenos oportunistas de mamíferos, y colonizan nichos como la piel, las fosas nasales y diversas membranas mucosas. Varias especies son de gran importancia médica o veterinaria. S. aureus, la especie patógena mas significativa en humanos, es también una causa importante de infección y enfermedad en diversos hospedadores animales, lo que tiene un impacto relevante en la salud pública.Trabajo publicado en Cagliada, Maria del Pilar Lilia y Galosi, Cecilia Mónica (comps.). I Congreso de Microbiología Veterinaria. Libro de resúmenes. La Plata: Facultad de Ciencias Veterinarias, 2021.Facultad de Ciencias Veterinaria

Staphylococcus pseudintermedius y el enfoque de Una Salud

The interdependence between human and animal health linked to the environment in which they coexist are the bases of the One Health approach. Staphylococcus pseudintermedius is a skin and mucous membrane commensal in animals, especially in dogs, where it can cause different diseases. In recent years, S. pseudintermedius has been recognized as a zoonotic agent;although it does not colonize humans under normal conditions, it can cause disease under certain circumstances. Staphylococcus pseudintermedius has several virulence factors such as enzymes, surface proteins, and toxins that are involved in adherence, biofilm formation, and evasion of the immune response. In addition, it has multiple antimicrobial resistance which makes treatment difficult, and also constitutes a reservoir of resistance genes that can be transmitted to other species. Finally, conventional methods used in the diagnostic laboratory do not allow proper identification of S. pseudintermedius; therefore, in many occasions, diagnosis cannot be confirmed.The objective of this review was to describe S. pseudintermedius from a One Health approachEl concepto de Una Salud se basa en la interdependencia entre la salud humana y la salud animal, vinculadas al medio ambiente en el que coexisten. Staphylococcus pseudintermedius es un microorganismo que forma parte de la microbiota de la piel y las mucosas en animales, especialmente en la especie canina de la que se suele aislar como agente etiológico de diferentes enfermedades. En los últimos años fue reconocido como un agente zoonótico. Si bien en condiciones normales no coloniza al hombre, puede causarle enfermedad bajo ciertas circunstancias. S. pseudintermedius cuenta con varios factores de virulencia, tales como enzimas, proteínas de superficie y toxinas, que participan en la adherencia, formación de biopelículas y evasión de la respuesta inmune. Posee resistencia múltiple a los agentes antimicrobianos, lo que dificulta el tratamiento de las infecciones que produce y, además, constituye un reservorio de genes de resistencia que pueden transmitirse a otras especies. Finalmente, los métodos convencionales usados en el laboratorio de diagnóstico no son suficientes para su identificación, por lo que muchas veces, no es posible confirmar su participación como agente etiológico de una enfermedad. El propósito de esta revisión fue exponer las características que permiten considerar a S. pseudintermedius en el marco de Una Salud

Healthy horses from Buenos Aires province colonized with methicillin-resistant Staphylococcus aureus

Con el objetivo de buscar Staphylococcus aureus resistentes a la meticilina (SARM) en equinos sanos, se tomaron 177 muestras del vestíbulo nasal a partir de animales utilizados con distintos propósitos. Los aislamientos se caracterizaron por pruebas bioquímicas y la sensibilidad a 13 antimicrobianos por el método de difusión en agar. La resistencia a la meticilina y macrólidos se confirmó mediante PCR. También por PCR se detectó la leucocidina de Panton Valentine (PVL). La tipificación del cassette cromosómico (SCCmec) se realizó por PCR múltiple. La relación genética entre los aislamientos se estableció por electroforesis en campo pulsado y tipificación multilocus de secuencia. En el 5% (9/177) de los equinos se aisló SARM. Siete de los 9 SARM (78%) presentaron resistencia a eritromicina y clindamicina, con fenotipo MLSB inducible. Todas las cepas fueron sensibles a los demás antibióticos. Todos los aislamientos fueron SCCmec IV. Se diferenciaron 2 tipos clonales: el A ST-5 en 7/9 aislamientos y el B ST-30 en 2/9 con PVL positivo. Ambos clones de SARM hallados en la población equina son los más frecuentes SARMCA en la población humana argentina. La posibilidad de transmisión de cepas de SARM entre humanos y animales es preocupante.In order to search for methicillin-resistant Staphylococcus aureus (MRSA) in healthy horses, 177 samples were taken from the nasal vestibule from animals used for different purposes. The isolates were characterized by biochemical tests and susceptibility to 13 antimicrobial agents by the agar diffusion method. Resistance to methicillin and macrolides was confirmed by PCR. Panton Valentine leukocidin factor (PVL) was detected by PCR. The Staphylococcal chromosomal cassette (SCCmec) was characterized by multiplex PCR. The genetic relationship between isolates was performed by pulsed field electrophoresis and multilocus sequence typing. MRSA was isolated in 5% (9/177) of the equines. Seven of the 9 MRSA (78%) showed resistance to erythromycin and clindamycin, with MLSB inducible phenotype. All the strains were susceptible to the other antimicrobial agents tested. All the isolates were SCCmec IV. Two clonal types were differentiated: A ST-5 in 7/9 isolates and B ST-30 in 2/9 with PVL positive. Both MRSA clones detected in equine population are the most frequent in the CA-MRSA human population of Argentina. The possibility of transmission of MRSA strains between humans and animals is worrisome.Facultad de Ciencias VeterinariasUniversidad de Buenos Aire

Antimicrobial resistance of Streptococcus pneumoniae from invasive pneumococcal diseases in Latin American countries: a systematic review and meta-analysis

BackgroundInvasive pneumococcal disease has declined since pneumococcal conjugate vaccine introduction in Latin America and the Caribbean (LAC). However, serotype distribution and antimicrobial resistance patterns have changed.MethodsWe conducted a systematic review to evaluate the frequency of antimicrobial resistance of Streptococcus pneumoniae from invasive disease in LAC. Articles published between 1 January 2000, and 27 December 2022, with no language restriction, were searched in major databases and gray literature. Pairs of reviewers independently selected extracted data and assessed the risk of bias in the studies. The quality of antimicrobial resistance (AMR) studies was evaluated according to WHO recommendations (PROSPERO CRD42023392097).ResultsFrom 8,600 records identified, 103 studies were included, with 49,660 positive samples of S. pneumoniae for AMR analysis processed. Most studies were from Brazil (29.1%) and Argentina (18.4%), were cross-sectional (57.3%), reported data on AMR from IPD cases (52.4%), and were classified as moderate risk of bias (50.5%). Resistance to penicillin was 21.7% (95%IC 18.7–25.0, I2: 95.9), and for ceftriaxone/cefotaxime it was 4.7% (95%IC 3.2–6.9, I2: 96.1). The highest resistance for both penicillin and ceftriaxone/cefotaxime was in the age group of 0 to 5 years (32.1% [95%IC 28.2–36.4, I2: 87.7], and 9.7% [95%IC 5.9–15.6, I2: 96.9] respectively). The most frequent serotypes associated with resistance were 14 for penicillin and 19A for ceftriaxone/cefotaxime.ConclusionApproximately one-quarter of invasive pneumococcal disease isolates in Latin America and the Caribbean displayed penicillin resistance, with higher rates in young children. Ongoing surveillance is essential to monitor serotype evolution and antimicrobial resistance patterns following pneumococcal conjugate vaccine introduction

Circulation of multiresistant methicillin resistant Staphylococcus aureus in pig farms from Argentina

Se describe el resultado de la búsqueda de Staphylococcus aureus resistentes a meticilina (SARM) en la cavidad nasal de cerdos de cría intensiva, durante los años 2019 y 2021, con el objetivo de dar a conocer si existe circulación, en Argentina, de este patógeno relevante en la salud pública. Se procesaron 64 muestras obtenidas en 5 granjas de las provincias de Buenos Aires, Santa Fe y San Luis. Se aislaron 19 (29,7%) SARM, confirmados por la presencia del gen mecA y con resistencia múltiple (3 o más familias de antibióticos). Todos los SARM fueron sensibles a rifampicina, nitrofurantoína y linezolid y resistentes a cloranfenicol, tetraciclina y ciprofloxacina. La resistencia a eritromicina fue del 68,4% (13/19), a clindamicina del 78,9% (15/19) y la no sensibilidad a gentamicina del 57,9% (11/19). Las edades de los animales portadores fueron de 27, 80, 120 y 154 días y, en todas las granjas muestreadas, se identificó SARM. Los aislamientos del año 2019 se caracterizaron como complejo clonal 1 (SARM de la comunidad) prevalentes en la población humana. Estos hallazgos demuestran la circulación de SARM en cerdos de producción intensiva y resaltan la necesidad de implemen-tar su control para tomar medidas apropiadas que eviten su diseminación.In the present work, the presence of methicillin- resistant Staphylococcus aureus (MRSA) was evaluated in the nasal cavity of pigs from intensive farms during 2019 and 2021, with the aim to report MRSA circulation of this relevant public health pathogen in Argentina. A total of 64 samples obtained from 5 farms in Buenos Aires, Santa Fe and San Luis provinces were studied. Nineteen (29.7 %) MRSA were isolated, confirmed by the presence of the mecA gene; all isolates were multidrug resistant (3 or more families of antibiotics). All MRSA were susceptible to rifampin, nitrofurantoin, and linezolid and resistant to chloramphenicol, tetracycline, and ciprofloxacin. Resistance to erythromycin, to clindamycin and non-susceptibility to gentamicin was 68.4 % (13/19), 78.9 % (15/19), and 57,9 % (11/19), respectively. Carrier animals were 27, 80, 120 and 154 days old, and MRSA was identified in all the sampled farms. The isolates from 2019 were characterized as clonal complex 1 (community MRSA), which is prevalent in the human population. These findings show the circulation of MRSA in pigs from intensive farms and highlight the need for surveillance to take appropriate measures to prevent its spread.Facultad de Ciencias Veterinaria

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

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 β-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. In addition to the differential levels of β-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. 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.Facultad de Ciencias Veterinaria

Molecular Genetic Profiling of Clinical and Foodborne Strains of Enterococci with High Level Resistance to Gentamicin and Vancomycin

Enterococci often acquire antimicrobial resistance through horizontal gene transfer. Relatedness between enterococci with high level resistance to gentamicin and vancomycin isolated from humans, food and hospital environment in Tandil County (Argentina) was investigated. PCR amplification for species determination was carried out. Resistance to seven antimicrobials was studied; virulence genes (esp, cylA), vancomycin and gentamicin resistance genes were investigated. In the isolates with high level antimicrobial resistance (gentamicin, vancomycin), pulse-field gel electrophoresis was performed. Vancomycin-resistant E. faecium (n:13) were recovered from human, food and hospital environment samples. All the isolates expressed high-level vancomycin and teicoplanin (vanA genotype), as well high-level gentamicin and streptomycin resistance. Vancomycin-resistant E. faecium were distributed among seven clonal types; esp gene was detected in clinical strains. There was no clonal relationship with food vanA E. faecium, but these strains could pose a risk in intra/inter genus transfer of vanA determinant to human-adapted strains. High-level gentamicin resistant E. faecalis (n:7) were recovered from human and food samples. Glycopeptide resistance was not observed; cylA gene was detected in most of the clinical high-level gentamicin resistant E. faecalis isolates. PFGE patterns showed four clonal types in high-level gentamicin resistant E. faecalis strains; there was demonstrated clonal relatedness between isolates from different origin. In Argentina, this is the first study showing a clonal relationship between high-level gentamicin resistant E. faecalis isolated from food and humans. These results encourage the study of dissemination of clonal complexes with mobile resistance genes.Facultad de Ciencias Médica

Geographical migration and fitness dynamics of Streptococcus pneumoniae

Streptococcus pneumoniae is a leading cause of pneumonia and meningitis worldwide. Many different serotypes co-circulate endemically in any one location1,2. The extent and mechanisms of spread and vaccine-driven changes in fitness and antimicrobial resistance remain largely unquantified. Here using geolocated genome sequences from South Africa (n = 6,910, collected from 2000 to 2014), we developed models to reconstruct spread, pairing detailed human mobility data and genomic data. Separately, we estimated the population-level changes in fitness of strains that are included (vaccine type (VT)) and not included (non-vaccine type (NVT)) in pneumococcal conjugate vaccines, first implemented in South Africa in 2009. Differences in strain fitness between those that are and are not resistant to penicillin were also evaluated. We found that pneumococci only become homogenously mixed across South Africa after 50 years of transmission, with the slow spread driven by the focal nature of human mobility. Furthermore, in the years following vaccine implementation, the relative fitness of NVT compared with VT strains increased (relative risk of 1.68; 95% confidence interval of 1.59–1.77), with an increasing proportion of these NVT strains becoming resistant to penicillin. Our findings point to highly entrenched, slow transmission and indicate that initial vaccine-linked decreases in antimicrobial resistance may be transient

Staphylococcus pseudintermedius’s PBP4 Is Directly Associated with the Dissociated Oxacillin and Cefoxitin Phenotype

Staphylococcus pseudintermedius is an important pathogen responsible for infections in dogs and in humans. The emergence and dissemination of methicillin-resistant S. pseudintermedius (MRSP) and the multidrug resistance frequently seen in this species make difficult the treatment of these pathogens. The cefoxitin disk is widely used as a marker of methicillin resistance mediated by the mecA gene in Staphylococcus aureus and other staphylococcal species; however, it is not useful to detect β-lactam resistance of MRSP in clinical microbiology laboratories. The purpose of this study was to elucidate the molecular bases of the dissociated phenotype between oxacillin and cefoxitin antibiotics. By using a combinatorial approach that included the Penicillin-Binding Proteins’ (PBP) profile, their affinity for different β-lactam antibiotics and the analyses of PBPs’ sequence, we provide evidence that PBP4 showed still affinity for its target cefoxitin, impairing its phenotypic resistant detection in MRSP. Together, these findings provide evidence that S. pseudintermedius PBP4 is directly associated with the dissociated oxacillin and cefoxitin phenotype

<i>Staphylococcus pseudintermedius</i> y el enfoque de Una Salud : Staphylococcus pseudintermedius and the One Health approach

El concepto de Una Salud se basa en la interdependencia entre la salud humana y la salud animal, vinculadas al medio ambiente en el que coexisten. Staphylococcus pseudintermedius es un microorganismo que forma parte de la microbiota de la piel y las mucosas en animales, especialmente en la especie canina dela que se suele aislar como agente etiológico de diferentes enfermedades. En los últimos años fue reconocido como un agente zoonótico. Si bien en condiciones normales no coloniza al hombre, puede causarle enfermedad bajo ciertas circunstancias. S. pseudintermedius cuenta con varios factores de virulencia, tales como enzimas, proteínas de superficie y toxinas, que participan en la adherencia, formación de biopelículas y evasión de la respuesta inmune. Posee resistencia múltiple a los agentes antimicrobianos, lo que dificulta el tratamiento de las infecciones que produce y, además, constituye un reservorio de genes de resistencia que pueden transmitirse a otras especies. Finalmente, los métodos convencionales usados en el laboratorio de diagnóstico no son suficientes para su identificación, por lo que muchas veces, no es posible confirmar su participación como agente etiológico de una enfermedad. El propósito de esta revisión fue exponer las características que permiten considerar a S. pseudintermedius en el marco de Una Salud.The interdependence between human and animal health linked to the environment in which they coexist are the bases of the One Health approach. Staphylococcus pseudintermedius is a skin and mucous membrane commensal in animals, especially in dogs, where it can cause different diseases. In recent years, S. pseudintermedius has been recognized as a zoonotic agent; although it does not colonize humans under normal conditions, it can cause disease under certain circumstances. Staphylococcus pseudintermedius has several virulence factors such as enzymes, surface proteins, and toxins that are involved in adherence, biofilm formation, and evasion of the immune response. In addition, it has multiple antimicrobial resistance which makes treatment difficult, and also constitutes a reservoir of resistance genes that can be transmitted to other species. Finally, conventional methods used in the diagnostic laboratory do not allow proper identification of S. pseudintermedius; therefore, in many occasions, diagnosis cannot be confirmed. The objective of this review was to describe S. pseudintermedius from a One Health approach.Facultad de Ciencias Veterinaria