Antimicrobial activity of doripenem against Gram-negative pathogens: results from INVITA-A-DORI Brazilian study

In vitro activity of doripenem and comparator antimicrobial agents was evaluated against Gram-negative bacilli recently isolated from Brazilian private hospitals that were enrolled in the INVITA-A-DORI Brazilian Study. A total of 805 unique Gram-negative bacilli were collected from patients hospitalized at 18 medical centers between May/08 and March/09. Each hospital was asked to submit 50 single Gram-negative bacilli isolated from blood, lower respiratory tract or intraabdominal secretions. Bacterial identification was confirmed and antimicrobial susceptibility testing was performed using Clinical Laboratory Standards Institute (CLSI) microdilution method at a central laboratory. CLSI M100-S21 (2011) or US-FDA package insert criteria (tigecycline) was used for interpretation of the antimicrobial susceptibility results. Doripenem was as active as meropenem and more active than imipenem against E. coli and K. pneumoniae isolates. A total of 50.0 percent of Enterobacter spp. isolates were resistant to ceftazidime but 85.7 percent of them were inhibited at doripenem MICs < 1 µg/mL. Polymyxin B was the only agent to show potent activity against Acinetobacter spp. (MIC50/90, < 0.5/1 µg/mL) and P. aeruginosa (MIC50/90, 1/2 µg/mL). Although high rates of imipenem (53.1 percent) and meropenem (44.5 percent) resistance were detected among P. aeruginosa, doripenem showed MIC50 of 16 µg/mL against imipenem-resistant P. aeruginosa and inhibited a greater number of imipenem-resistant P. aeruginosa (10.5 percent) at MIC values of < 4 µg/mL than did meropenem (0.0 percent). In this study, doripenem showed similar in vitro activity to that of meropenem and retained some activity against imipenem-resistant P. aeruginosa isolated from Brazilian medical centers.

Antimicrobial activity of ceftobiprole against Gram-negative and Gram-positive pathogens: results from INVITA-A-CEFTO Brazilian study

Ceftobiprole is a broad-spectrum cephalosporin with potent activity against staphylococci, including those resistant to oxacillin, as well as against most Gram-negative bacilli including Pseudomonas aeruginosa. In this study, the in vitro activity of ceftobiprole and comparator agents was tested against bacterial isolates recently collected from Brazilian private hospitals. A total of 336 unique bacterial isolates were collected from hospitalized patients between February 2008 and August 2009. Each hospital was asked to submit 100 single bacterial isolates responsible for causing blood, lower respiratory tract or skin and soft tissue infections. Bacterial identification was confirmed and antimicrobial susceptibility testing was performed using CLSI microdilution method at a central laboratory. The CLSI M100-S21 (2011) was used for interpretation of the antimicrobial susceptibility results. Among the 336 pathogens collected, 255 (75.9 percent) were Gram-negative bacilli and 81 (24.1 percent) were Gram-positive cocci. Although ceftobiprole MIC50 values for oxacillin resistant strains were two-fold higher than for methicillin susceptible S. aureus, ceftobiprole inhibited 100 percent of tested S. aureus at MICs < 4 µg/mL. Polymyxin B was the only agent to show potent activity against Acinetobacter spp. (MIC50/90, 0.5/1 µg/mL), and P. aeruginosa (MIC50/90, 1/2 µg/mL). Resistance to broad-spectrum cephalosporins varied from 55.3-68.5 percent and 14.3-28.5 percent among E. coli and Klebsiella spp. isolates, respectively; with ceftobiprole MIC50 > 6 µg/mL for both species. Our results showed that ceftobiprole has potent activity against staphylococci and E. faecalis, which was superior to that of vancomycin. Our data also indicates that ceftobiprole demonstrated potency comparable to that of cefepime and ceftazidime against key Gram-negative species.

Avaliaçäo do perfil de sensibilidade e caracterizaçäo de Enterococcus spp. isolados em hospitais da América Latina / Antimicrobial susceptibility profile and molecular characterization of Enterococcus spp. isolated in Latin American

A vigilância de microrganismos multi-resistentes tem sido incentivada com o intuito de impedir a disseminação da resistência bacteriana aos antimicrobianos. Como o perfil de sensibilidade antimicrobiana pode variar de acordo com a região geográfica, foi conduzido um estudo de vigilância entre quatro países (l 5 centros médicos), com o objetivo de caracterizar melhor as amostras de enterococos da América Latina e avaliar o modo de disseminação de enterococos resistentes à vancomicina (ERV) nessa região. Foram analisadas 436 amostras clínicas de enterococos, coletadas em 1998 e 1999. Estas amostras foram submetidas a testes de sensibilidade para vancomicina, teicoplanina, ampicilina, gentamicina, estreptomicina, ciprofloxacina, cloranfenicol, doxiciclina e um novo antimicrobiano, quinupristindaifopristin (Synercid©). Inicialmente, foram testadas 188 amostras pelo método de micro-diluição em caldo (Brasil) e 248 amostras pelo método de difusão com discos (Argentina, Chile e Venezuela). Os enterococos que demonstraram sensibilidade diminuída à vancomicina e/ou quinupristindalfopristin, foram re-testados pelo método de micro-diluição em caldo (padrão ouro) e E-test©, e novamente identificados através dos métodos bioquímicas convencionais. A pesquisa dos genes de resistência à vancomicina (vanA, vanB, vanC1, vanC2-3 ) e a quinupristin-daifopristin (satA e satG) foi realizada através do método de reação em cadeia da polimerase (PCR), e a avaliação do modo de disseminação desta resistência foi feita por eletroforese pulsada em gel de agarose (PFGE). A ampicilina inibiu o crescimento de lOO por cento dos E. faecalís isolados no Brasil e 97 por cento dos isolados nos demais países. Entretanto, 31 por cento das amostras de E. faecíum foram resistentes à ampicilina. A resistência à vancomicina foi confirmada em 16 amostras de enterococos (3,7 por cento), sendo 14 amostras de E. faecíum e duas amostras de E. faecalis. Apenas duas destas amostras de E. faecium foram isolados na Argentina; as demais amostras foram isoladas em diferentes hospitais brasileiros (todos na cidade de São Paulo). As amostras de ERVs resistentes à vancomicina apresentaram fenótipo VanA e gene vanA, com exceção de uma única amostra isolada em Curitiba (Brasil), na qual não foi detectado nenhum gene de resistência. A resistência a quinuprístin-dalfopristin no Brasil não está relacionada aos principais genes (satA e satG) descritos para esse tipo de resistência em ...(au)