ABSTRACT Shiga toxin-producing Escherichia coli (STEC) infections are responsible for acute illnesses and deaths in humans. Cattle and humans are exposed to STEC through faeces and contaminated food and water. The big six and O157 STEC serogroups are important food and water-borne human pathogens. Additionally, Stx1a, Stx2a and Stx2c subtypes are highly associated with the haemolytic uremic syndrome. This study aimed to determine Shiga toxin-subtypes, the presence of antigen 43 families, the genotypic and phenotypic antimicrobial susceptibility profiles, O-serogrouping, phylotypes and phylogenetic relatedness of STEC of calf origin. Sixteen STEC isolates from calf origin were analysed. PCR was performed to determine Stx subtypes, serogroups, the presence of ag43 I and II and phylotypes. The antimicrobial profile was evaluated and the presence of PMQR and fosfomycin genes was determined by PCR. The clonal relatedness of STEC was studied by PFGE. The genotypes stx1a+c, stx1a+, stx1a+/stx2e+, stx1a+c/stx2e and stx2a were detected. Ag43 II was the most prevalent among subfamilies. STEC isolates were serotyped as O103 (n=5) and O111 (n=6). Fifty per cent of the isolates were classified as B1 phylogroup, 4/16 as E, 1/16 as C, and 1/16 as F. Non-O157 STEC isolates showed a high level of diversity, independent of the geographical and farm-origin. Isolates were resistant to ampicillin, ciprofloxacin, gentamicin, and fosfomycin-trometamol. The gene fosA7 was detected in 1 isolate. The virulence profiles, including Shiga toxin-subtypes and serogroups, denote the potential harm of non-O157 STEC isolates to humans. We also confirmed that circulating non-O157 STEC from cattle present genetic heterogeneity and are susceptible to antibiotics.

Abstract Antimicrobial resistance due to carbapenemase production in Enterobacteriaceaeclinical isolates is a global threat. Klebsiella pneumoniae harboring the blaKPCgene is one ofthe major concerns in hospital settings in Latin America.The aim of this study was to characterize the antibiotic resistance mechanisms and to typifyfour carbapenem-resistant K. pneumoniae clinical isolates from the city of Manizales, Colombia.We identified blaKPC-3in all four isolates by polymerase chain reaction and subsequentsequencing. The plasmid-mediated quinolone resistance genes qnrB19-like and aac(6)Ib-cr;fosfomycin resistance gene fosA and an insertion sequence IS5-like in mgrB (colistin resistance)were also detected. Sequence types ST11 with capsular type wzi75, and ST258 with wzi154,were characterized. The blaKPC-3gene was mobilized in a 100-kb IncFIB conjugative plasmidwith vagCD toxin-antitoxin system.This work reports multiple resistance genes in blaKPC-producing K. pneumoniae and the firstoccurrence of ST11 clinical isolates harboring blaKPC-3in Latin America.

Resumen La resistencia a antibióticos mediada por la producción de carbapenemasas en aislamientos clínicos de Enterobacteriaceae es una amenaza mundial. Klebsiella pneumoniae portador de blaKPC es uno de los mayores problemas a nivel hospitalario en Latinoamérica. El objetivo de este estudio fue caracterizar los mecanismos de resistencia antibiótica y tipificar cuatro aislamientos clínicos de K. pneumoniae resistentes a carbapenems obtenidos en la ciudad de Manizales, Colombia. Se identificó blaKPC-3 en todos los aislamientos mediante reacción en cadena de polimerasa y secuenciación. También se detectaron los genes de resistencia transferible a quinolonas qnrB19-like y aac(6’)Ib-cr y a fosfomicina fosA, y la secuencia de inserción \S5-like en mgrB (asociada a la resistencia a colistina). Se caracterizaron los secuenciotipos ST11 (cápsula wzi75) y ST258 (cápsula wzi154). Se comprobó que blaKPC-3 fue movilizado por un plásmido conjugativo IncFIB-vagCD de 100kb. En este trabajo se reportan múltiples genes de resistencia en K. pneumoniae productor de blaKPC y se describen por primera vez aislamientos clínicos ST11 productores de blaKPC-3 en Latinoamérica.

Abstract Introduction: Latin America is a large and diverse region, comprising more than 600 million inhabitants and one million physicians in over 20 countries. Resistance to antibacterial drugs is particularly important in the region. This paper describes the design, implementation and results of an international bi-lingual (Spanish and Portuguese) online continuing interprofessional interactive educational program on hospital-acquired infections and antimicrobial resistance for Latin America, supported by the American Society for Microbiology. Methods: Participation, satisfaction and knowledge gain (through pre and post tests) were used. Moreover, commitment to change statements were requested from participants at the end of the course and three months later. Results: There were 1169 participants from 19 Latin American countries who registered: 57% were physicians and 43% were other health care professionals. Of those, 1126 participated in the course, 46% received a certificate of completion and 54% a certificate of participation. There was a significant increase in knowledge between before and after the course. Of 535 participants who took both tests, the grade increased from 59 to 81%. Commitments to change were aligned with course objectives. Discussion: Implementation of this educational program showed the feasibility of a continent-wide interprofessional massive course on hospital acquired-infections in Latin America, in the two main languages spoken in the region. Next steps included a new edition of this course and a "New Challenges" course on hospital-acquired infections, which were successfully implemented in the second semester of 2015 by the same institutions.

Salmonella enterica serovar Heidelberg ranks among the most prevalent causes of human salmonellosis in the United States and Canada, although it has been infrequently reported in South American and European countries. Most Salmonella infections are self-limiting; however, some invasive infections require antimicrobial therapy. In this work we characterized an oxyimino-cephalosporin resistant S. Heidelberg isolate recovered from an inpatient in a Buenos Aires hospital. CMY-2 was responsible for the β-lactam resistance profile. S. Heidelberg contained a 97 kb plasmid belonging to the Inc N group harboring blaCMY-2. ISEcp1 was located upstream blaCMY-2 driving its expression and mobilization. The isolate belonged to sequence type 15 and virotyping revealed the presence of sopE gene. In this study we identified the first CMY-2 producing isolate of S. Heidelberg in Argentina and even in South America.

Salmonella enterica serovar Heidelberg es uno de los principales agentes causantes de salmonelosis en humanos en Estados Unidos y Canadá, sin embargo, resulta infrecuente en los países de Sudamérica y Europa. En este trabajo se caracterizó un aislamiento de S. Heidelberg resistente a oximino-cefalosporinas recuperado de un paciente internado en un hospital de la Ciudad de Buenos Aires. Se evidenció la presencia de un plásmido de 97 kb perteneciente al grupo de incompatibilidad IncN, portador del gen blaCMY-2. ISEcp1 fue localizado corriente arriba de blaCMY-2, promoviendo su expresión y movilización. El aislamiento de S. Heidelberg correspondió al secuenciotipo 15 y en la virotipificación se detectó el gen sopE. En este trabajo describimos por primera vez la producción de CMY-2 en una cepa de S. Heidelberg en nuestro país y América Latina.

Objective: We describe two cases of treatment failure due to intra-treatment acquisition of antibiotic resistant microorganisms with the aim of highlighting the possible molecular mechanisms by which treatment failure occurred. Patients and Methods: We analyzed the clinical histories and the isolates obtained from 2 patients, one with a urinary tract infection (UTI) by E. coli, initially treated with cefuroxim (to which the isolate was susceptible), and another with osteoarthritis (OA) treated initially with meropenem plus vancomycin, developing K. pneumoniae susceptible to meropenem. During treatment, in both patients, resistant microorganisms were isolated, and empirical therapy was modified, initially with ceftriaxone and afterwards meropenem in case 1, and adding amikacin in case 2. Both strains (per patient) were compared by PFGE and resistance genes were sought by PCR. Results: Regarding the UTI, the initial strain acquired an IncFIB SHV-5-producing plasmid. In the OA case, the initial susceptible strain was substituted by a CTX-M-9 and AadB-AadA2-Aac(6')Ib-producing K. pneumoniae.

Se describen dos casos de fallo terapéutico en niños con infecciones por enterobacterias, asociado a cambios intra-tratamiento de la sensibilidad a antibacterianos con el objetivo de describir posibles mecanismos de falla terapéutica con estudio molecular de los agentes infecciosos detectados. Se analizaron las historias clínicas y las cepas de dos pacientes, uno con infección urinaria por E. coli inicialmente tratado con cefuroximo (al cual era sensible) y otro con osteoartritis tratado de forma empírica con mero-penem-vancomicina con hemocultivos positivos a K. pneumoniae sensible a meropenem. En la evolución, ambos pacientes desarrollaron durante el tratamiento una infección por microorganismos resistentes, cambiándose a ceftriaxona y luego meropenem en el primer caso y agregando amikacina en el segundo. Se compararon las cepas por electroforesis de campo pulsado y se estudiaron mecanismos de resistencia por RPC. En el caso de ITU, la cepa inicial adquirió un plásmido IncFIB productor de la BLEE SHV-5. En el caso de OA, la cepa sensible inicial fue sustituida por otra cepa de K. pneumoniae productora de CTX-M-9, (AadB-AadA2), Aac(6')1b.