Molecular epidemiology of CTX-M producing Enterobacteriaceae isolated from bloodstream infections in Rio de Janeiro, Brazil: emergence of CTX-M-15

OBJECTIVE: The present studywas designed to evaluate the molecular epidemiology of CTX-M producing Klebsiella pneumoniae, Enterobacter cloacae and Escherichia coli isolated from bloodstream infections at tertiary care hospitals in the State of Rio de Janeiro, Brazil. MATERIAL AND METHODS: A total of 231 nonduplicate Enterobacteriaceae were isolated from five Brazilian hospitals between September 2007 and September 2008. The antimicrobial susceptibility testing was performed by disk diffusion method according to the Clinical Laboratory Standard Institute. Isolates showing resistance to third-generation cephalosporins were screened for ESBL activity by the double-disk synergy test. The presence of blaCTX-M , blaCTX-M-15 and blaKPC genes was determined by Polymerase Chain Reaction (PCR) amplification andDNA sequencing. The molecular typing of CTX-M producing isolateswas performed by pulsed-field gel electrophoresis (PFGE). RESULTS AND DISCUSSION: Ninety-three isolates were screened as ESBL positive and 85 (91%) were found to carry CTX-M-type, as follows: K. pneumoniae 59 (49%), E. cloacae 15 (42%), and E. coli 11 (15%). Ten isolates resistant for carbapenems in K. pneumoniae were blaKPC-2 gene positive. Among CTX-M type isolates, CTX-M-15 was predominant in more than 50% of isolates for K. pneumoniae, E. coli, and E. cloacae. PFGE analysis of CTX-M producing isolates showed the predominance of CTX-M-15 in 10 of 24 pulsotypes in K. pneumoniae, 6 of 13 in E. cloacae and 3 of 6 in E. coli. CTX-M-15 was also predominant among KPC producing isolates. In conclusion, this study showed that CTX-M-15 was circulating in Rio de Janeiro state in 2007-2008. This data reinforce the need for continuing surveillance because this scenario may have changed over the years.

Detection of blaOXA-23 in Acinetobacter spp. isolated from patients of a university hospital

INTRODUCTION: Acinetobacter spp. have emerged as notorious pathogens involved in healthcareassociated infections. Carbapenems are important antimicrobial agents for treating infections due to multidrug resistant Acinetobacter spp. Different mechanisms may confer resistance to these drugs in the genus, particularly production of class D carbapenemases. OXA-23-like family has been pointed out as one of the predominant carbapenamases among Acinetobacter. The present work aimed to investigate the occurrence of OXA-23-like carbapenemases among Acinetobacter isolates recovered from patients of a university hospital in Niterói, RJ, Brazil. METHODS: Antimicrobial susceptibility profiles were determined by disk-diffusion. Imipenem resistant isolates were submitted to Modified Hodge Test in order to screen for carbapenemase production, and later to polymerase chain reaction (PCR) to investigate the presence of blaOXA-23. RESULTS: Imipenem and meropenem resistance rates were 71.4% and 69.7%, respectively. The Modified Hodge Test revealed carbapenemase production among 76 (89.4%) of the 85 imipenem resistant isolates analyzed; according to PCR results, 81 isolates (95.4%) carried the blaOXA-23 gene. CONCLUSIONS: OXA-23-like enzymes may be an important mechanism of carbapenem resistance among isolates present in the hospital studied.

Síntese e atividade antiestafilocócica do derivado 2-acetóxi-1, 4-naftoquinona / Synthesis and anti-staphylococcus activity of 2-acetoxi-1, 4-naftoquinona derivative

O derivado 2-acetóxi-1, 4-naftoquinona (DNQ), sintetizado por Ferreira, foi testado contra seis diferentes espécies de bactérias isoladas de pacientes do Hospital Universitário Antônio Pedro (HUAP). A droga exibiu atividade apenas contra cepas Gram-positivas (zonas de inibição = 12 mm, em testes preliminares): Enterococcus faecalis, Staphylococcus aureus e Staphylococcus epidermidis. Para os isolados de S. aureus, as concentrações mínimas inibitórias (CMIs) e mínimas bactericidas (CMBs) variaram de 16mug a 256 mug/ml e de 64 mug a 512 mug/ml, respectivamente. Através da espectrofotometria de absorção em 560nm, DNQ originou cinéticas de inibição diretamente proporcionais às suas concentrações, com 2CMI promovendo resposta lítica (apenas na 1ª hora de tratamento) nas cepas sensíveis à oxacilina. Em nível de viabilidade celular (UFC/ml), os efeitos do derivado também cresceram na razão direta do aumento de sua concentração, com 2 x CMI acarretando uma resposta bactericida bem nítida (já na 2ª hora de ação), contra as cepas sensíveis ao Beta-lactâmico. Apesar da menor atividade do DNQ em relação aos antibióticos de uso em clínica, estamos continuando os estudos com o derivado, agora, na tentativa de, através da modificação de sua estrutura, ampliar o seu espectro de ação e a sua atividade antibacteriana.