One hundred and twenty-four Pseudomonas aeruginosa isolates were selected for antimicrobial susceptibility testing with anti-pseudomonal agents, MIC determination for polymyxin B and metallobeta-lactamase detection (genes bla SPM , bla VIM-1 , bla NDM-1 and bla IMP ). According to the imipenem and/or meropenem susceptibility profile, a set of randomly selected isolates (12 isolates carbapenem-susceptible and 12 isolates carbapenem-resistant) were evaluated for heteroresistance to polymyxin B. Heteroresistance testing was performed by plating the isolates onto increasing concentrations of polymyxin B (from 0 to 8.0 mg l -1). The population analysis profile (PAP) was defined as the ratio of the number of colony-forming units on the plate with the highest concentration of polymyxin B at which bacterial growth occurred against the number of colonyforming units on the plate without antibiotic. Isolates presenting subpopulations that exhibited growth at polymyxin B concentrations ¢2 mg l -1 were considered heteroresistant. Isolates containing subpopulations that grew at polymyxin B concentrations at least twice as high as the original MIC but ,2 mg l -1 were considered heterogeneous. Antimicrobial susceptibility testing results indicated a variable degree of susceptibility: high levels of resistance to gentamicin (30.6 %) and imipenem (29.0 %); low levels of resistance to aztreonam (1.6 %) and ciprofloxacin (4.8 %). All isolates were susceptible to polymyxin B: MIC 50 and MIC 90 were 1 mg l -1 and 2 mg l -1 , respectively. Thirty-seven isolates (30 %) were carbapenem-resistant. Four isolates resistant to carbapenems were positive for bla IMP . There were no heteroresistant subpopulations in the carbapenem-susceptible group, but three isolates presented heterogeneous subpopulations. The PAP frequency ranged from 2.1¾10 . In the carbapenem-resistant group, one isolate was heteroresistant. Six isolates in this group presented heterogeneous subpopulations. In the resistant population, the PAP frequency ranged from 2.1¾10 "7 to 2.6¾10 . In this study, polymyxin B heteroresistance in P. aeruginosa was uncommon and occurred in only one carbapenem-resistant isolate, despite the fact that several isolates presented heterogeneous subpopulations with increased polymyxin B MICs.

In recent years, different resistance genes have been found in Acinetobacter spp., especially in the species A. baumannii. We describe two isolates of carbapenem-resistant A. nosocomialis harboring ISAba1-bla OXA-23 and bla OXA-51 found in patients from the city of Porto Alegre, southern Brazil. To the best of the authors' knowledge, this is the first report of carbapenem-resistant A. nosocomialis in Latin America. In recent years, Acinetobacter spp. have been described as important pathogens in outbreaks of nosocomial infection worldwide, especially in intensive care units (1). In particular, the species A. baumannii has presented an increased rate of antimicrobial resistance (2, 3). Carbapenems, once regarded as the treatment of choice for infections caused by Acinetobacter spp., are no longer effective in some cases (2). The main mechanism of carbapenem resistance among Acinetobacter spp. is the production of ␤-lactamases, in particular class D ␤-lactamases (oxacillinases), associated with promoter gene sequence ISAba1 (3). Among oxacillinases, the most prevalent one is bla , identified in mobile genetic elements. Chromosomally located bla OXA-51 genes, in turn, do not always confer carbapenem resistance but are used to identify A. baumannii, as it is believed to be intrinsic to this species (4-6).Traditionally, the bla OXA-23 and bla OXA-51 genes are associated with A. baumannii only, but recently some authors have described the presence of such genes in non-A. baumannii species. The bla OXA-23 gene was found in A. pittii (Acinetobacter genomic species 3) in the Irish Republic in 2006 and in A. nosocomialis (Acinetobacter genomic species 13TU) in South Korea and Thailand in 2012 (7, 8). Moreover, bla OXA-51 preceded by ISAba1 has been found in carbapenem-resistant A. nosocomialis in Taiwan (9).In this study, we evaluated a set of non-A. baumannii species and found two isolates of carbapenem-resistant A. nosocomialis with the ISAba1-bla OXA-23 and bla OXA-51 genes, obtained from patients living in the city of Porto Alegre, southern Brazil.A total of 118 isolates were evaluated, obtained over the year 2011 from clinical specimens of Acinetobacter spp. previously identified using conventional methods. Isolates were identified to the species level using gyrB multiplex PCR as described by Higgins et al., with few modifications (10). Briefly, we used seven primers at a total reaction volume of 25 l, consisting of 0.2 M each primer, 1.5 mM MgCl 2 , 1ϫ 0.2 mM each deoxynucleoside triphosphate (dNTP), and 1 U Taq DNA polymerase. The PCR program consisted of initial denaturation at 94°C for 2 min, followed by 30 cycles of denaturation (94°C for 1 min), annealing (56°C for 30 s), and extension (72°C for 1 min), with a final extension step at 72°C for 10 min. Species identification was also evaluated by PCR with primers targeting the 16S-23S rRNA intergenic transcribed spacer (ITS) region, followed by sequence analysis (11). Oxacillinase genes (bla OXA-23 , bla OXA-24 , bla OXA-51 , bla , and bla OXA-143 ) were ident...

These findings evidenced that the multiplex PCR of the gyrB is a feasible and simple method to identify isolates of the ABC at the species level.

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O aumento gradativo da incidência de infecções fúngicas é resultado de vários fatores e, um deles, é o número crescente de pacientes com imunossupressão severa. Apesar de novos medicamentos estarem sendo introduzidos para minimizar este problema, o desenvolvimento de resistência diante das drogas antifúngicas se tornou evidente, em especial nos pacientes que recebem tratamentos longos, ou que estão recebendo antifúngicos de forma profilática, onde, em ambos os casos, pode haver mudanças na microbiota humana, dando origem a um ambiente favorável às espécies resistentes. As características farmacológicas, a frequência e, em particular, os mecanismos de resistência para atual classe de agentes antifúngicos são debatidos nesta revisão.