Made available in DSpace on 2015-04-11T13:38:48Z (GMT). No. of bitstreams: 1 Nayanne Cristina.pdf: 1826134 bytes, checksum: fa7345995de48191f1f917ea832980fd (MD5) Previous issue date: 2011-06-30 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The production of extended-spectrum beta-lactamases (ESBLs) among clinical isolates of Gram-negative bacteria is an important mechanism of resistance to -lactam antibiotics. It is the major cause of treatment failure using cephalosporins, thereby causing limitations in therapeutic choice and are enzymes mediated by plasmids that have the hability to hidrolisy oximino-cephalosporins and aztreonam. This study aimed to identify key genes responsible for production of ESBLs in Gram-negative Enterobacteriaceae and Pseudomonadaceae family. There were 12 Gram-negative bacteria that were positive for ESBL isolated from patients with hematologic malignancies treated at HEMOAM Foundation from July 2007 to August 2008. The detection and identification of genes blaTEM, blaSHV, blaCTX-M and blaOXA were performed by PCR and nucleotide sequencing. E. coli bacteria were more frequent among ESBL isolates. All isolates were susceptible to imipenem and were resistant to chloramphenicol and tetracycline. The bacteria carried genes for TEM, SHV, CTX-M and OXA on both chromosomes and in plasmids. The presence of multigene (blaTEM, blaSHV, blaCTX-M and blaOXA) and the non-antibiotic resistance detected in the -lactam and non-enterobacteria Enterobacteriaceae isolated from clinical specimens in this research is relevant because it provides information about the presence of this threat antibiotic resistance in our region. / A produção de beta-lactamases de espectro estendido (ESBLs) entre os isolados clínicos de bactérias Gram-negativas é um importante mecanismo de resistência aos antibióticos -lactâmicos. É a maior causa de falha terapêutica utilizando as cefalosporinas, ocasionando assim limitações na escolha terapêutica e são mediadas por plasmídeos e têm a capacidade de hidrolisar oximino-cefalosporinas e aztreonam. Este trabalho teve como objetivo identificar os principais genes responsáveis pela produção das ESBLs em bactérias Gram-negativas da família Enterobacteriaceae e Pseudomonadaceae. Foram estudadas 12 bactérias Gram-negativas que apresentaram fenótipo positivo para ESBL isoladas de pacientes portadores de doenças hematológicas atendidos na Fundação HEMOAM no período de julho de 2007 a agosto de 2008. A detecção e identificação dos genes blaTEM, blaSHV, blaCTX-M e blaOXA foram realizadas por PCR e seqüenciamento nucleotídico. A E. coli foi a bactéria mais freqüente entre os isolados. Todos os isolados ESBL positivos foram suscetíveis ao imipenem e apresentaram resistência ao cloranfenicol e a tetraciclina. As bactérias carreavam genes para TEM, SHV, CTX-M e OXA tanto em cromossomos como em plasmídeos. A presença de multigenes (blaTEM, blaSHV, blaCTX-M e blaOXA) e a resistência a antibióticos não--lactâmicos detectados nas enterobactérias e não-enterobactérias isoladas de amostras clínicas nesta pesquisa se torna relevante pois, oferece informações em nível de saúde pública da presença deste tipo de resistência aos antibióticos em nossa região.

Klebsiella spp. are opportunistic pathogens that cause hospital and community acquired infections such as pneumonia, urinary tract infection, septicaemia, soft tissue infections, liver abscess, and meningitis. Multidrug-resistant strains possessing extended-spectrum β-lactamases (ESBLs) has become an increasing problem worldwide. The over use and, in some cases, misuse of antibiotics in humans and in animal husbandry has been cited as a responsible factor in the development of drug resistance in all bacterial species. The advancing age; female gender, hospital crossinfection, the food chain trade and human migrations have contributed to increase the risk for community-acquired ESBL. A total of 223 isolates collected in 2006 and 2007 at Royal Infirmary of Edinburgh, Scotland, 219 K. pneumoniae, 2 K. oxytoca, 1 Enterobacter cloacae, and one isolate Salmonella enterica were identified by API 20E and confirmed genotypically with gyrA PCR-RFLP method. The antimicrobial susceptibility results showed that 34 (15.2%), 36 (16.1%), 35 (15.7%), 45 (20.2%), 30 (13.5%) and 55 (24.7%) of these strains were found to be resistant to cefotaxime, ceftazidime, ceftriaxone, naladixic acid, ciprofloxacin and cefoxitin. None of the isolates were found resistant to meropenem keeping carbapenems the drug of choice for the treatment of multiresistant isolates. The overall frequency of ESBL producers observed in this study was 35 (15.7%) most of them 32/35 (91.4%) were from K. pneumoniae. The genetic analysis showed that SHV β-lactamases were detected in 32, whereas TEM and CTX-M were detected in 24 and 16 respectively. From the ESBL-producing isolates, molecular methods identified nine strains possessing ESBL-SHV genes (1 strain blaSHV-5, 1 strain blaSHV-80 and 8 strains blaSHV-12), whereas the remaining were from the “non-ESBL” producing strains. Conjugation methods demonstrated that 29/32 isolates harboured transferable blaSHV genes. The large SHV transposon-borne promoters were amplified from only one non-transferable blaSHV-11, 15 isolates produced the small SHV transposon-borne promoters. Furthermore, the IS26 was found 73bp upstream of the blaSHV gene in all small SHV transposon-borne promoters. A new blaLEN gene was identified from K. pneumoniae (KpII) phylogenetic group but remained susceptible to all cephalosporins. Sixteen (7.3%) of K. pneumoniae isolates were found to be producers of the CTX-M- 15 ESBL, of which two isolates (12.5%) were reported to be from communityacquired infections. The insertion sequence ISEcp1 was detected by sequencing 48 nucleotides upstream of blaCTX-M-15 in all isolates but one. Five different clones of CTX-M-15-producing isolates were identified by PFGE. The findings indicated a higher prevalence of qnr genes than in previous studies but still low in general. By PCR, 18 (8%) (11 qnrB1, 2 qnrB6 and 5 qnrA1) genes were identified from K. pneumoniae isolates. Also, the findings indicated the frequent coexpression of fluoroquinolones and ESBLs resistance in the same isolate. Two K. oxytoca strains were isolated from urine and blood specimens of hospitalized patients. Both strains were positive for the blaOXY-2 gene. One strain showed resistance to pencillins, monbactams, cephalosporins including cefotaxime and ceftazidime but was not inhibited by clavulanic acid. It differed by an amino acid substitution Ala237→Thr, which enhances the binding of cefotaxime. S1-nuclease plasmid profiles were obtained for some isolates. A total of one to two plasmids, ranging in size from approximately 40 to 210 kb, were observed per strain. The plasmids from 24 ESBL K. pneumoniae strains were assigned to be IncN or IncFII replicons. Analysis of phylogenetic groups showed that the majority of K. pneumoniae isolates were belonged to KpI-type. Both K. oxytoca strains were assigned to be KoII phylogenetic group based on rpoB and gyrA sequencing. Integrons are capable of capturing and mobilizing genes called gene cassettes which play an important role in the dissemination of antimicrobial resistance through horizontal transmission. In fact, the present study indicated a high frequency of occurrence of class 1 integrons among ESBL-positive K pneumoniae. Three isolates positive for class 1 integrons were found positive for class 2 integrons as well. Class 1 integrons including dfr, aadA and ereA2 gene cassettes have been identified by sequencing, which confer resistance to trimethoprim, streptomycin/spectinomycin and erythromycin respectively. In conclusion, the results from this thesis report the emergence of hospital and community-acquired highly resistant CTX-15 β-lactamase in the Edinburgh, Scotland. The prevalence of ESBL-producing isolates in Scotland is still much lower than in many other European countries. The dissemination of SHV- and TEM- β- lactamase types in this study is more predominate than CTX-M-15.

The emergence of extended spectrum β-lactamase (ESBL) producing Enterobacteriaceae worldwide has led to an increased use of carbapenems and may drive the development of carbapenem resistance. Existing mechanisms are mainly due to acquired carbapenemases or the combination of ESBL-production and reduced outer membrane permeability. The focus of this thesis was to study the development of carbapenem resistance in Escherichia coli in the presence and absence of acquired β-lactamases. To this end we used the resistance plasmid pUUH239.2 that caused the first major outbreak of ESBL-producing Enterobacteriaceae in Scandinavia. Spontaneous carbapenem resistance was strongly favoured by the presence of the ESBL-encoding plasmid and different mutational spectra and resistance levels arose for different carbapenems. Mainly, loss of function mutations in the regulators of porin expression caused reduced influx of antibiotic into the cell and in combination with amplification of β-lactamase genes on the plasmid this led to high resistance levels. We further used a pharmacokinetic model, mimicking antibiotic concentrations found in patients during treatment, to test whether ertapenem resistant populations could be selected even at these concentrations. We found that resistant mutants only arose for the ESBL-producing strain and that an increased dosage of ertapenem could not prevent selection of these resistant subpopulations. In another study we saw that carbapenem resistance can even develop in the absence of ESBL-production. We found mutants in export pumps and the antibiotic targets to give high level resistance albeit with high fitness costs in the absence of antibiotics. In the last study, we used selective amplification of β-lactamases on the pUUH239.2 plasmid by carbapenems to determine the cost and stability of gene amplifications. Using mathematical modelling we determined the likelihood of evolution of new gene functions in this region. The high cost and instability of the amplified state makes de novo evolution very improbable, but constant selection of the amplified state may balance these factors until rare mutations can establish a new function. In my studies I observed the influence of β-lactamases on carbapenem resistance and saw that amplification of these genes would further contribute to resistance. The rapid disappearance of amplified arrays of resistance genes in the absence of antibiotic selection may lead to the underestimation of gene amplification as clinical resistance mechanism. Amplification of β-lactamase genes is an important stepping-stone and might lead to the evolution of new resistance genes.

Extended Spectrum β-Lactamases (ESBLs) are produced by the Enterobacteriaceae bacterial family, mainly by E. coli and K. pneumoniae. As these species are some of the main causes of urinary tract infections and sepsis, ESBL-production is of major concern. Occurrence of ESBLs also gives rise to concern as it is increasing epidemically. This because the genes coding for ESBLs (i.e. bla-genes) are located on plasmids replicating and spreading the replicated copies independently. Plasmids replicate by replicons. Plasmids with the same replicon variant are grouped into the same plasmid family. The aim of this study was to detect plasmid families carrying bla-genes in E. coli and K. pneumoniae from clinical (n = 6) and environmental water (n = 22) isolates. Plasmid family prevalence was examined. Association between plasmid families and bla-genes was also examined. Plasmid families were detected by a PBRT kit (PCR Based Replicon Typing), a multiplex PCR kit that detected 30 replicons, whereof 27 replicons representing the 27 plasmid families in Enterobacteriaceae, and three novel replicons. The IncF plasmid family was the most prevalent for both species in both clinical and environmental isolates. IncF seemed to be prevalent for all examined ESBLs, but it was difficult to associate one bla-gene with one plasmid family as most isolates carried several bla-genes and several plasmid families. / Extended Spectrum β-Lactamases (ESBLs) produceras av bakteriefamiljen Enterobacteriaceae, främst av E. coli och K. pneumoniae. Eftersom dessa arter är bland de vanligaste orsakerna till urinvägsinfektioner och sepsis är ESBL-produktion ett allvarligt problem. ESBL är också oroande eftersom det sprids epidemiskt. Detta möjliggörs av att generna som kodar för ESBLs (s.k. bla-gener) ligger på plasmider, som replikerar och sprider de replikerade plasmidkopiorna självständigt. Plasmider replikeras som s.k. replikon. Plasmider med samma replikonvariant tillhör samma plasmidfamilj. Syftet med detta arbete var att detektera plasmidfamiljer som bär bla-gener i E. coli och K. pneumoniae isolerade från kliniska prov (n = 6) och miljöprov (n = 22) från Helge Å. Plasmidfamiljernas prevalens undersöktes, liksom sambandet mellan plasmidfamiljer och bla-gener. Plasmidfamiljerna detekterades med ett PBRT-kit (PCR Based Replicon Typing), ett multiplext PCR-kit som detekterade 30 replikon varav 27 replikon som representerar de 27 plasmidfamiljer som finns i Enterobacteriaceae och tre nya replikon. Plasmidfamiljen IncF var vanligast förekommande i båda arter i både kliniska isolat och miljöisolat. IncF verkade förekomma för alla undersökta typer av ESBL, men det var generellt svårt att förknippa en bla-gen med en plasmidfamilj, eftersom de flesta isolaten bar flera bla-gener och flera plasmidfamiljer.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Enterobactérias produtoras de ESBLs são descritas tanto no ambiente hospitalar quanto na comunidade em todo o mundo. No Brasil, esses microrganismos também têm emergido como uma causa importante de infecções, sendo as enzimas CTX-M as prevalentes. O objetivo deste estudo foi analisar diferentes aspectos genotípicos relacionados à expressão da resistência aos antimicrobianos em cepas Escherichia coli e de Salmonella spp, tais como: a diversidade de ESBLs, os genes de resistência aos antimicrobianos e o conteúdo plasmidial. Os aspectos epidemiológicos das cepas produtoras de ESBLs também foram investigados. Foram estudadas 88 cepas de enterobactérias, sendo 43 E. coli e 45 cepas de Salmonella spp., de origem hospitalar e da comunidade (principalmente alimentos), isoladas na cidade do Rio de Janeiro. A expressão de ESBL foi observada em sete cepas de E. coli (7/43, 16,3%) e em uma cepa de Salmonella Typhimurium (1/45, 2,3%) e as enzimas foram identificadas como variantes de CTX-M e SHV-5, respectivamente. Entre as cepas de E. coli, a enzima CTX-M-2 foi a mais frequente (n = 4), sendo detectada em cepas isoladas de swab retal de pacientes hospitalizados, enquanto as enzimas CTX-M-59 (uma variante de CTX-M) (n = 1) e CTX-M-9 (n = 2) foram identificadas em cepas isoladas a partir de espécimes clínicos. Salmonella Typhimurium produtora de SHV-5 foi isolada do ambiente hospitalar (fórmula infantil). As cepas de E. coli produtoras das enzimas CTX-M pertenceram a grupos filogenéticos (A, B1, D) e STs (ST34, ST69, ST101) diferentes, sendo os genes blaCTX-M identificados em plasmídeos com tipo de replicon IncA/C de cerca de 150 kb (blaCTX-M-2, blaCTX-M-9, blaCTX-M-59) ou 80 kb (blaCTX-M-2). A cepa de S. Typhimurium produtora de SHV-5 pertenceu a um único clone (A-ST19) e o gene blaSHV-5 foi identificado em plasmídeo com o replicon IncL/M com aproximadamente 55Kb. Foi identificado pela primeira vez no Brasil o ST313 em um clone de S. Typhimurium (D-ST313), comumente associado com doenças invasivas severas, particulamente no continente africano. Genes que codificam para a resistência aos antimicrobianos não-beta-lactâmicos e integrons classe 1 foram identificados entre as cepas de E. coli e de Salmonella spp. multirresistentes produtoras ou não de ESBLs. Em conclusão: i) nossos resultados referentes à E. coli confirmaram a disseminação de enzimas CTX-M (principalmente variantes do grupo CTX-M-2) desde, pelo menos, o ano de 2000, em hospitais no Rio de Janeiro; demonstraram a implicação dos plasmídeos IncA/C na disseminação de genes blaCTX-M; indicaram a possível evolução intra-plasmídeo de blaCTX-M-59 a partir de blaCTX-M-2; a observação da diversidade e multiplicidade de plasmídeos poderiam fornecer plataformas genéticas para a dispersão de diferentes genes e/ou elementos de resistência aos antimicrobianos; ii) em relação à Salmonella spp. este estudo descreveu, pela primeira vez, o isolamento, a partir de fórmula infantil, de uma cepa de S. Typhimurium produtora de ESBL; foi demonstrada a associação do gene blaSHV-5 com plasmídeo do tipo IncL/M, que é considerado epidêmico; foi identificado o clone D-ST313 de S. Typhimurium, que está associado a doenças invasivas severas no continente africano, que reuniu cepas isoladas exclusivamente do ambiente hospitalar. / ESBL-producing Enterobacteriaceae have been described in hospitals and in the community worldwide. In Brazil, ESBL-producing Enterobacteriaceae have also emerged as an important cause of infections, being CTX-M enzymes the most prevalent ESBLs. The objective of this study was to analyze different genotypic aspects related to expression of antimicrobial resistance in isolates of Escherichia coli and Salmonella spp., such as: diversity of ESBLs, antibiotic resistance genes and plasmid content. Epidemiological features of ESBL-producing isolates were also investigated. We studied 88 isolates of enterobacteria, 43 E. coli and 45 Salmonella serotypes of hospital and community (mainly food) origin, isolated in the city of Rio de Janeiro. ESBL expression was observed in seven E. coli isolates (7/43; 16,3%) and in one Salmonella Typhimurium (1/45; 2,3%) and the enzymes identified as CTX-M variants and SHV-5, respectively. Among the E. coli isolates, CTX-M-2 was the most frequent (n=4), being detected in isolates recovered from rectal swabs of hospitalized patients, whereas CTX-M-59 (a CTX-M-2-variant) (n=1) and CTX-M-9 (n=2) were identified in E. coli isolated from clinical specimens. SHV-5-producing S. Typhimurium was isolated from the hospital environment (infant formula). CTX-M-producing E. coli belonged to different phylogenetic groups (A, B1, D) and STs (ST34, ST69, ST101), being blaCTX-M genes were identified in IncA/C plasmids of approximately 150 kb (blaCTX-M-2, blaCTX-M-9, blaCTX-M-59) or 80 kb (blaCTX-M-2). SHV-5-producing S. Typhimurium belonged to a single clone (A-ST19) and blaSHV-5 gene was identified in IncL/M plasmids of approximately 55Kb. This study first described in Brazil the isolation of S. Typhimurium belonging to ST313 commonly associated with severe invasive diseases, particularly in Africa. Genes encoding resistance to non-beta-lactams and class 1 integrons were found among ESBL-producers and non-ESBL-producing multidrug-resistant E. coli and Salmonella spp. In conclusion: i) our results related to E. coli confirmed the dissemination of CTX-M-enzymes (especially CTX-M-2-variants) since, at least, the beginning of the last decade in Rio de Janeiro clinical settings; demonstrated the implication of IncA/C plasmids in the spread of blaCTX-M genes; indicated the possible intra-plasmid evolution of blaCTX-M-59 from blaCTX-M-2; observation of the diversity and multiplicity of plasmids would provide genetic platforms for spread of different antibiotic resistance genes and/or elements; ii) in relation to Salmonella spp. this study described for the first time, the isolation, from infant formula, ESBL- producing S. Typhimurium; has been demonstrated the association of blaSHV-5 to plasmids belonging to IncL/M group, that can be considered epidemic plasmids; was identified D-ST313 clone in S. Typhimurium, commonly associated with severe invasive diseases, particularly in Africa, among isolates recovered exclusively from hospital.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Enterobactérias produtoras de ESBLs são descritas tanto no ambiente hospitalar quanto na comunidade em todo o mundo. No Brasil, esses microrganismos também têm emergido como uma causa importante de infecções, sendo as enzimas CTX-M as prevalentes. O objetivo deste estudo foi analisar diferentes aspectos genotípicos relacionados à expressão da resistência aos antimicrobianos em cepas Escherichia coli e de Salmonella spp, tais como: a diversidade de ESBLs, os genes de resistência aos antimicrobianos e o conteúdo plasmidial. Os aspectos epidemiológicos das cepas produtoras de ESBLs também foram investigados. Foram estudadas 88 cepas de enterobactérias, sendo 43 E. coli e 45 cepas de Salmonella spp., de origem hospitalar e da comunidade (principalmente alimentos), isoladas na cidade do Rio de Janeiro. A expressão de ESBL foi observada em sete cepas de E. coli (7/43, 16,3%) e em uma cepa de Salmonella Typhimurium (1/45, 2,3%) e as enzimas foram identificadas como variantes de CTX-M e SHV-5, respectivamente. Entre as cepas de E. coli, a enzima CTX-M-2 foi a mais frequente (n = 4), sendo detectada em cepas isoladas de swab retal de pacientes hospitalizados, enquanto as enzimas CTX-M-59 (uma variante de CTX-M) (n = 1) e CTX-M-9 (n = 2) foram identificadas em cepas isoladas a partir de espécimes clínicos. Salmonella Typhimurium produtora de SHV-5 foi isolada do ambiente hospitalar (fórmula infantil). As cepas de E. coli produtoras das enzimas CTX-M pertenceram a grupos filogenéticos (A, B1, D) e STs (ST34, ST69, ST101) diferentes, sendo os genes blaCTX-M identificados em plasmídeos com tipo de replicon IncA/C de cerca de 150 kb (blaCTX-M-2, blaCTX-M-9, blaCTX-M-59) ou 80 kb (blaCTX-M-2). A cepa de S. Typhimurium produtora de SHV-5 pertenceu a um único clone (A-ST19) e o gene blaSHV-5 foi identificado em plasmídeo com o replicon IncL/M com aproximadamente 55Kb. Foi identificado pela primeira vez no Brasil o ST313 em um clone de S. Typhimurium (D-ST313), comumente associado com doenças invasivas severas, particulamente no continente africano. Genes que codificam para a resistência aos antimicrobianos não-beta-lactâmicos e integrons classe 1 foram identificados entre as cepas de E. coli e de Salmonella spp. multirresistentes produtoras ou não de ESBLs. Em conclusão: i) nossos resultados referentes à E. coli confirmaram a disseminação de enzimas CTX-M (principalmente variantes do grupo CTX-M-2) desde, pelo menos, o ano de 2000, em hospitais no Rio de Janeiro; demonstraram a implicação dos plasmídeos IncA/C na disseminação de genes blaCTX-M; indicaram a possível evolução intra-plasmídeo de blaCTX-M-59 a partir de blaCTX-M-2; a observação da diversidade e multiplicidade de plasmídeos poderiam fornecer plataformas genéticas para a dispersão de diferentes genes e/ou elementos de resistência aos antimicrobianos; ii) em relação à Salmonella spp. este estudo descreveu, pela primeira vez, o isolamento, a partir de fórmula infantil, de uma cepa de S. Typhimurium produtora de ESBL; foi demonstrada a associação do gene blaSHV-5 com plasmídeo do tipo IncL/M, que é considerado epidêmico; foi identificado o clone D-ST313 de S. Typhimurium, que está associado a doenças invasivas severas no continente africano, que reuniu cepas isoladas exclusivamente do ambiente hospitalar. / ESBL-producing Enterobacteriaceae have been described in hospitals and in the community worldwide. In Brazil, ESBL-producing Enterobacteriaceae have also emerged as an important cause of infections, being CTX-M enzymes the most prevalent ESBLs. The objective of this study was to analyze different genotypic aspects related to expression of antimicrobial resistance in isolates of Escherichia coli and Salmonella spp., such as: diversity of ESBLs, antibiotic resistance genes and plasmid content. Epidemiological features of ESBL-producing isolates were also investigated. We studied 88 isolates of enterobacteria, 43 E. coli and 45 Salmonella serotypes of hospital and community (mainly food) origin, isolated in the city of Rio de Janeiro. ESBL expression was observed in seven E. coli isolates (7/43; 16,3%) and in one Salmonella Typhimurium (1/45; 2,3%) and the enzymes identified as CTX-M variants and SHV-5, respectively. Among the E. coli isolates, CTX-M-2 was the most frequent (n=4), being detected in isolates recovered from rectal swabs of hospitalized patients, whereas CTX-M-59 (a CTX-M-2-variant) (n=1) and CTX-M-9 (n=2) were identified in E. coli isolated from clinical specimens. SHV-5-producing S. Typhimurium was isolated from the hospital environment (infant formula). CTX-M-producing E. coli belonged to different phylogenetic groups (A, B1, D) and STs (ST34, ST69, ST101), being blaCTX-M genes were identified in IncA/C plasmids of approximately 150 kb (blaCTX-M-2, blaCTX-M-9, blaCTX-M-59) or 80 kb (blaCTX-M-2). SHV-5-producing S. Typhimurium belonged to a single clone (A-ST19) and blaSHV-5 gene was identified in IncL/M plasmids of approximately 55Kb. This study first described in Brazil the isolation of S. Typhimurium belonging to ST313 commonly associated with severe invasive diseases, particularly in Africa. Genes encoding resistance to non-beta-lactams and class 1 integrons were found among ESBL-producers and non-ESBL-producing multidrug-resistant E. coli and Salmonella spp. In conclusion: i) our results related to E. coli confirmed the dissemination of CTX-M-enzymes (especially CTX-M-2-variants) since, at least, the beginning of the last decade in Rio de Janeiro clinical settings; demonstrated the implication of IncA/C plasmids in the spread of blaCTX-M genes; indicated the possible intra-plasmid evolution of blaCTX-M-59 from blaCTX-M-2; observation of the diversity and multiplicity of plasmids would provide genetic platforms for spread of different antibiotic resistance genes and/or elements; ii) in relation to Salmonella spp. this study described for the first time, the isolation, from infant formula, ESBL- producing S. Typhimurium; has been demonstrated the association of blaSHV-5 to plasmids belonging to IncL/M group, that can be considered epidemic plasmids; was identified D-ST313 clone in S. Typhimurium, commonly associated with severe invasive diseases, particularly in Africa, among isolates recovered exclusively from hospital.