INTRODUCTION: The aim of this study was to identify a rapid and simple phenotypic method for extended-spectrum β-lactamase (ESBL) detection in Enterobacter cloacae. METHODS: A total of 79 consecutive, non-repeated samples of E. cloacae were evaluated. Four phenotypic methods were applied for ESBL detection, results were compared to multiplex polymerase chain reaction (PCR) as the gold standard reference method: 1) ceftazidime and cefotaxime disks with and without clavulanate, both with boronic acid added; 2) disk approximation using cefepime and amoxicillin/clavulanate; 3) ESBL screening by minimum inhibitory concentration (MIC) ≥ 16µg/mL and 4) by MIC ≥ 2µg/mL for cefepime. RESULTS: Method 4 showed the best combination of sensitivity (100%) and specificity (94%). CONCLUSIONS: MIC ≥ 2µg/mL for cefepime would be very useful for the phenotypic detection of ESBL in samples of E. cloacae.

Several studies have been conducted in recent years to elucidate the structure, function and significance of AcrB, MarA, SoxS and RamA in Salmonella enterica. In this study, the relative quantification of acrB, soxS, marA and ramA genes expression was evaluated in 14 strains of S. enterica, with or without accompanying mutations in the quinolone resistance-determining regions of the gyrA gene, that were exposed to ciprofloxacin during the exponential growth phase. The presence of ciprofloxacin during the log phase of bacterial growth activated the genes marA, soxS, ramA and acrB in all S. enterica strains analyzed in this study. The highest expression levels for acrB were observed in strains with gyrA mutation, and marA showed the highest expression in the strains without mutation. Considering only the strains with ciprofloxacin minimum inhibitory concentration values < 0.125 [1]g/mL (sensitive to ciprofloxacin), the most expressed gene in the strains both with and without mutations was acrB. In the strains with ciprofloxacin minimum inhibitory concentration values > 0.125 [1]g/mL (low susceptibility), with and without mutations in gyrA, the most expressed gene was marA. In this study, we observed that strains resistant to nalidixic acid may express genes associated with the efflux pump and the expression of the AcrAB-TolC pump genes seems to occur independently of mutations in gyrA.

The objective of the present study was to determine the frequency of Staphylococcus aureus nasal carriage among dialysis and kidney transplant patients, to identify the antimicrobial resistance profile of these strains and to verify their genetic profiles with the RW3A primer. The study included 159 individuals, comprising 111 dialysis and 48 kidney transplant patients. Of the 48 transplant patients, 75% were positive for S. aureus, whereas 49% of the 111 dialysis patients were carriers. Two samples yielded conflicting results for oxacillin sensitivity between the disk diffusion and minimum inhibitory concentration (MIC) assays: both were sensitive by the disk diffusion assay and resistant by MIC (4 μg/ml). In the antibiogram by disk diffusion, ten samples were resistant to cefoxitin, among which eight were also resistant to oxacillin. The resistance of the ten samples to cefoxitin by the disk diffusion assay was confirmed by MIC. Of the ten oxacillin-resistant samples, eight harbored the mecA gene. All samples were sensitive to vancomycin, and most were resistant to penicillin and demonstrated high rates of resistance to the other antimicrobials tested. The samples from dialysis patients exhibited a more homogenous genetic profile. Among the samples with a high percent similarity, no correlation with sensitivity or resistance to oxacillin was observed. According to the results of this study, the implementation of prevention and control measures, such as increased restrictions on prescriptions for antimicrobial drugs and nasal decontamination prior to high-risk procedures, is recommended.

The aim of this study was to characterize two metallo-β-lactamases (MBLs)-producing Pseudomonas aeruginosa clinical isolates showing meropenem susceptibility. Antimicrobial susceptibility was assessed by automated testing and Clinical and Laboratory Standards Institute agar dilution method. MBL production was investigated by phenotypic tests. Molecular typing was determined by pulsed field gel electrophoresis (PFGE). MBL-encoding genes, as well as their genetic context, were identified by polymerase chain reaction (PCR) and sequencing. The location of blaIMP-16 was determined by plasmid electrophoresis, Southern blot and hybridization. Transcriptional levels of blaIMP-16, mexB, mexD, mexF, mexY, ampC and oprD were determined by semi-quantitative real time PCR. The P. aeruginosa isolates studied, Pa30 and Pa43, showed imipenem and meropenem susceptibility by automated testing. Agar dilution assays confirmed meropenem susceptibility whereas both isolates showed low level of imipenem resistance. Pa30 and Pa43 were phenotypically detected as MBL producers. PFGE revealed their clonal relatedness. blaIMP-16 was identified in both isolates, carried as a single cassette in a class 1 integron that was embedded in a plasmid of about 60-Kb. Pa30 and Pa43 overexpressed MexAB-OprM, MexCD-OprJ and MexXY-OprM efflux systems and showed basal transcriptional levels of ampC and oprD. MBL-producing P. aeruginosa that are not resistant to meropenem may represent a risk for therapeutic failure and act as silent reservoirs of MBL-encoding genes.

Mutations into codons Aspartate-87 (62%) and Serine-83 (38%) in QRDR of gyrA were identified in 105 Salmonella strains resistant to nalidixic acid (94 epidemic and 11 of poultry origin). The results show a high incidence of mutations associated to quinolone resistance but suggest association with others mechanisms of resistance.

OBJETIVO: Verificar a prevalência de carreamento nasal, perfil fenotípico e genotípico de S. aureus isolados de estudantes de enfermagem. MÉTODOS: Estudo transversal, com população composta por 101 alunos, cursando as três primeiras séries do curso de graduação em Enfermagem no ano de 2008. S. aureus foi isolado de material biológico obtido dos vestíbulos nasais através de swab. A susceptibilidade à oxacilina e vancomicina foi determinada pelo teste de concentração inibitória mínima. A presença do gene MecA foi determinada pelo teste de reação em cadeia da polimerase. RESULTADOS: Verificou-se 90,1% de positividade para S. aureus. A frequência de resistência à oxacilina foi de 9,8% e todas as amostras foram sensíveis à vancomicina. A oito amostras resistentes À oxacilina apresentaram o gene MecA. CONCLUSÃO: A prevalência foi elevada. A resistência à oxacilna foi expressiva e todas as amostras foram sensíveis à vancomicina. As amostras resistentes à oxacilina carreavam o gene MecA.

OBJECTIVE: To investigate the prevalence of nasal entrainment, phenotypic and genotypic profile of Staphylococcus aureus, asisolated from nursing students. METHODS: A cross-sectional population of 101 students enrolled in the first three grades of the undergraduate nursing course in 2008. Staphylococcus aureus was isolated from biological material obtained from the swab through the nasal vestibules. Susceptibility to oxacillin and vancomycin was determined by minimum inhibitory concentration test. The mecA gene was identified by testing the polymerase chain reaction. RESULTS: There was a 90.1% positive finding of Staphylococcus aureus. The frequency of oxacillin resistance was 9.8%; all samples were sensitive to vancomycin. The eight strains resistant to oxacillin carried the mecA gene. CONCLUSION: The prevalence of Staphylococcus aureus was high. Oxacillin resistance was significant, but all strains were sensitive to vancomycin. Isolates resistant to oxacillin carried the mecA gene.

OBJETIVO: Verificar la prevalencia de transporte nasal, perfil fenotípico y genotípico de S. aureus aislados de estudiantes de enfermería. MÉTODOS: Estudio transversal, con población compuesta por 101 alumnos, cursando las tres primeras series del Pregrado en Enfermería en el año 2008. El S. aureus fue aislado del material biológico obtenido de los vestíbulos nasales a través de swab. La susceptibilidad a la oxacilina y vancomicina fue determinada por el test de concentración inhibitoria mínima. La presencia del gen MecA fue determinada por el test de reacción en cadena de la polimerasa. RESULTADOS: Se verificó el 90,1% de positividad para el S. aureus. La frecuencia de resistencia a la oxacilina fue de 9,8% y todas las muestras fueron sensibles a la vancomicina. Las ocho muestras resistentes a la oxacilina presentaron el gen MecA. CONCLUSION: La prevalencia fue elevada. La resistencia a la oxacilina fue expresiva y todas las muestras fueron sensibles a la vancomicina. Las muestras resistentes a la oxacilina transportaban el gen MecA.

OBJECTIVE: To investigate the prevalence of nasal entrainment, phenotypic and genotypic profile of Staphylococcus aureus, asisolated from nursing students. METHODS: A cross-sectional population of 101 students enrolled in the first three grades of the undergraduate nursing course in 2008. Staphylococcus aureus was isolated from biological material obtained from the swab through the nasal vestibules. Susceptibility to oxacillin and vancomycin was determined by minimum inhibitory concentration test. The mecA gene was identified by testing the polymerase chain reaction. RESULTS: There was a 90.1% positive finding of Staphylococcus aureus. The frequency of oxacillin resistance was 9.8%; all samples were sensitive to vancomycin. The eight strains resistant to oxacillin carried the mecA gene. CONCLUSION: The prevalence of Staphylococcus aureus was high. Oxacillin resistance was significant, but all strains were sensitive to vancomycin. Isolates resistant to oxacillin carried the mecA gene.

OBJETIVO: Verificar la prevalencia de transporte nasal, perfil fenotípico y genotípico de S. aureus aislados de estudiantes de enfermería. MÉTODOS: Estudio transversal, con población compuesta por 101 alumnos, cursando las tres primeras series del Pregrado en Enfermería en el año 2008. El S. aureus fue aislado del material biológico obtenido de los vestíbulos nasales a través de swab. La susceptibilidad a la oxacilina y vancomicina fue determinada por el test de concentración inhibitoria mínima. La presencia del gen MecA fue determinada por el test de reacción en cadena de la polimerasa. RESULTADOS: Se verificó el 90,1% de positividad para el S. aureus. La frecuencia de resistencia a la oxacilina fue de 9,8% y todas las muestras fueron sensibles a la vancomicina. Las ocho muestras resistentes a la oxacilina presentaron el gen MecA. CONCLUSION: La prevalencia fue elevada. La resistencia a la oxacilina fue expresiva y todas las muestras fueron sensibles a la vancomicina. Las muestras resistentes a la oxacilina transportaban el gen MecA.

OBJETIVO: Verificar a prevalência de carreamento nasal, perfil fenotípico e genotípico de S. aureus isolados de estudantes de enfermagem. MÉTODOS: Estudo transversal, com população composta por 101 alunos, cursando as três primeiras séries do curso de graduação em Enfermagem no ano de 2008. S. aureus foi isolado de material biológico obtido dos vestíbulos nasais através de swab. A susceptibilidade à oxacilina e vancomicina foi determinada pelo teste de concentração inibitória mínima. A presença do gene MecA foi determinada pelo teste de reação em cadeia da polimerase. RESULTADOS: Verificou-se 90,1% de positividade para S. aureus. A frequência de resistência à oxacilina foi de 9,8% e todas as amostras foram sensíveis à vancomicina. A oito amostras resistentes À oxacilina apresentaram o gene MecA. CONCLUSÃO: A prevalência foi elevada. A resistência à oxacilna foi expressiva e todas as amostras foram sensíveis à vancomicina. As amostras resistentes à oxacilina carreavam o gene MecA.

In a study of university students, the percentage nasal carriage of Staphylococcus aureus was 40.8% (102/250). Of the isolates, MIC50 of methicillin was 0.5 µg/mL and MIC90 was 1 µg/mL. Six (5.8%) isolates were methicillin-resistant and carried the mecA gene. These results suggest that community-associated methicillin-resistant S. aureus may be spreading in Brazil.

The antibiotics association is an alternative to treat infectious diseases, either caused by polymicrobial etiology or those caused by multidrug-resistant bacteria, such as Pseudomonas aeruginosa. In this study, the in vitro antimicrobial activity of the polymyxin B and ceftazidime combination was investigated in 20 clinical isolates of P. aeruginosa. Initially, the minimum inhibitory concentration (MIC) of those agents was determined by using the broth microdilution technique for each of the selected strains. Afterwards, based on MIC values, the antimicrobial effect of the polymyxin B and ceftazidime combination was evaluated by making use of "checkerboard" method. The results demonstrated that all P. aeruginosa strains studied were sensitive to polymyxin B, with MICs varying from 1 to 2 µg/ml. In relation to ceftazidime, MICs varied from 2 to 8 µg/ml in nine sensitive strains, and from 16 to 1.024 µg/ml in 11 strains resistant to that antibiotic. For all strains tested, the antimicrobial effect of the polymyxin B and ceftazidime combination was indifferent, thus suggesting that such an association, when used as a combined in vivo therapy, sometimes does not present any activity superior to the one obtained with monotherapy.

La asociación de antibióticos es una alternativa para tratar enfermedades infecciosas de etiología polimicrobiana o causadas por bacterias multiresistentes, como por ejemplo Pseudomonas aeruginosa. En el presente estudio, investigamos la actividad antimicrobiana in vitro de la combinación de polimixina B y ceftazidima en 20 muestras clínicas de P. aeruginosa. Inicialmente, la concentración inhibitoria mínima (CIM) de los agentes fue determinada por la técnica de microdiluición en caldo para cada una de las muestras seleccionadas. Posteriormente, con base en los valores de las CIMs, el efecto antimicrobiano de la combinación de la polimixina B y ceftazidima fue evaluado a través del método de "checkerboard". Los resultados demostraron que todas las muestras de P. aeruginosa estudiadas fueron sensibles a la polimixina B, con CIMs variando entre 1 y 2 µg/ml. En relación con la ceftazidima, las CIMs variaron de 2 a 8 µg/ml en nueve muestras sensibles, y de 16 a 1.024 µg/ml en 11 muestras resistentes a ese antibiótico. Para todas las muestras testadas, el efecto antimicrobiano de la combinación de polimixina B y ceftazidima fue indiferente, sugiriendo que esta asociación, cuando utilizada en la forma de terapia combinada in vivo, puede no presentar actividad superior a aquella obtenida por la monoterapia.

A associação de antibióticos é uma alternativa para tratar doenças infecciosas de etiologia polimicrobiana ou causadas por bactérias multirresistentes, como por exemplo, Pseudomonas aeruginosa. No presente estudo, investigamos a atividade antimicrobiana "in vitro" da combinação de polimixina B e ceftazidima, em 20 amostras clínicas de P. aeruginosa. Inicialmente, a concentração inibitória mínima (CIM) dos agentes foi determinada pela técnica de microdiluição em caldo para cada uma das amostras selecionadas. Posteriormente, com base nos valores das CIMs, o efeito antimicrobiano da combinação da polimixina B e ceftazidima foi avaliado por meio do método de "checkerboard". Os resultados demonstraram que todas as amostras de P. aeruginosa estudadas foram sensíveis à polimixina B, com CIMs variando entre 1 e 2 µg/ml. Em relação à ceftazidima, as CIMs variaram de 2 a 8 µg/ml, em nove amostras sensíveis, e de 16 a 1.024 µg/ml, em 11 amostras, resistentes a esse antibiótico. Para todas amostras testadas, o efeito antimicrobiano da combinação de polimixina B e ceftazidima foi indiferente, sugerindo que esta associação, quando utilizada na forma de terapia combinada in vivo, pode não apresentar atividade superior àquela obtida pela monoterapia.

This study investigated the prevalence and the susceptibility profile of Staphylococcus aureus samples isolated from clinical infections in a teaching hospital, Paraná - Londrina, cases between 2001 and 2004. The sensitivity test results for 74 strains to oxacillin and vancomycim, obtained by MicroScan® automated system (Dada Bering, Sacramento, California, USA, employing MicroScan® PC 12- gram positive Panels) were compared with the results obtained from the dilution agar method using different concentrations of antimicrobials. The data was obtained from the Hospital Infection Committee Control Data bank. The Staphylococcus aureus samples showed a large spectrum of resistance to the antimicrobials tested. The medium rate of prevalence of the S. aureus hospital infections was 16,3% and the medium rate of prevalence of the hospital infection, by oxacillin resistant S. aureus strains was 70,75%. It was not detected samples resistant to vancomycin using both methods. Among this 74 samples identified as oxacillin-resistant by MicroScan® system, 65 (83,75%) had their resistance confirmed by Dilution Agar Method. The difference between the results was not statistically significant. To the vancomycin, there was 100% of concordance in both methods.

En este estudio se investigó la prevalencia y el perfil de sensibilidad de muestras de Staphylococcus aureus aisladas de casos clínicos de infecciones hospitalarias, en un hospital de enseñanza, Londrina - Paraná, en el período de 2001 a 2004. Fue también comparado los resultados de las pruebas de susceptibilidad a la oxacilina y vancomicina de 74 cepas, obtenidos por el sistema automatizado MicroScan® (Dade Bering, Sacramento, California, EE.UU., utilizando Paneles MicroScan® PC 12 (Gram Positivo), con los resultados de la técnica de dilución en agar con diferentes concentraciones de estos antimicrobianos. Las informaciones fueron procedentes del banco de datos de las infecciones hospitalarias de la Comisión de Control de Infección Hospitalaria (CCIH). Las muestras de S. aureus presentaron un amplio espectro de resistencia frente a las drogas probadas. La tasa promedio de prevalencia de infecciones hospitalarias por S. aureus fue de 16,3% y la tasa promedio de prevalencia de muestras oxacilina resistentes fue de 70,75%. No se detectó muestras resistentes a la vancomicina por los 2 métodos. El método de dilución en agar confirmó la resistencia a la oxacilina en 65 de las 74 (83,75%). Muestras evaluadas por el sistema MicroScan® siendo que esta diferencia entre osa 2 métodos no fue estadísticamente significante. Para el antimicrobiano vancomicina, hubo concordancia de 100% entre los dos métodos.

Este estudo investigou a prevalência e o perfil de sensibilidade de amostras de Staphylococcus aureus isoladas de casos clínicos de infecções hospitalares, em um hospital de ensino, Londrina - Paraná, no período de 2001 a 2004. Foi também comparado os resultados dos testes de susceptibilidade a oxacilina e vancomicina de 74 cepas, obtidos pelo sistema automatizado MicroScan® (Dade Bering, Sacramento, Califórnia, USA, utilizando Painéis MicroScan® PC 12 (Gram Positivo), com os resultados da técnica de diluição em ágar com diferentes concentrações destes antimicrobianos. As informações foram procedentes do banco de dados das infecções hospitalares da Comissão de Controle de Infecção Hospitalar (CCIH). As amostras de S. aureus apresentaram amplo espectro de resistência frente as drogas testadas. A taxa média de prevalência de infecções hospitalares por S. aureus foi de 16,3% e a taxa média de prevalência de amostras oxacilina resistentes foi de 70,75%. Não se detectou amostras resistentes a vancomicina pelos 2 métodos. O método de diluição em ágar confirmou a resistência a oxacilina em 65 das 74 (83,75%) e as amostras avaliadas pelo sistema MicroScan® não apresentaram diferenças estatisticamente significantes. Para o antimicrobiano vancomicina, houve concordância em 100% entre os dois métodos.

The objective of this descriptive study was to perform an epidemiologic characterization of hospital infections in an Intensive Care Centre of a teaching hospital in the north of Paraná State, from June 2003 to June 2004. A number of 1304 patient discharges were identified, 208 out of which presented hospital infection. Hospital infection rate was 15.95%. Staphylococcus aureus was the most frequently isolated microorganism with an incidence rate of 12.98%, followed by Pseudomonas aeruginosa 12.5%, Acinetobacter baumannii 9.61%; other microorganisms presented lower percentages. With respect to nosocomial infections topography, pneumonia had the highest incidence rate: 66.34%; urinary tract infections presented a 22.11% incidence rate, surgical site, 5.76% and the vascular system, 1.92%. Amongst the respiratory infections, S. aureus presented a 15.94% incidence rate, A baumannii, 13.76%, and P. aeruginosa, 9.42%. Regarding urinary tract infections, Candida sp. showed a 32.60% incidence rate, P. aeruginosa, 32.60%, E. coli, 10.86% and Enterobacter sp., 10.86%. Antimicrobial susceptibility test results showed that A. baumannii presented a sensitivity rate of 69,07 % to carbapenens. All S. aureus samples were sensitive to vancomycin and 34.5% were sensitive to oxacillin. Mortality incidence rate with respect to hospital infections was 27.88%.

Se trata de un estudio descriptivo cuyo objetivo fue estudiar la caracterización epidemiológica de las infecciones hospitalarias en un Centro de Terapia Intensiva de un hospital de enseñanza, en la región Norte de Paraná, en el período de junio de 2003 a junio de 2004. Fueron contabilizadas 1304 salidas de pacientes y, de este total 208 pacientes presentaron infección hospitalaria. La tasa de incidencia de infección hospitalaria fue de un 15,95%. Staphylococcus aureus fueron los microorganismos más encontrados con la incidencia de un 12,98%, seguido de Pseudomonas aeruginosa con un 12,5%, Acinetobacter baumannii un 9,61%. Los demás presentaron porcentajes menores. Con relación a las topografías de infecciones la neumonía fue la más incidente entre las infecciones hospitalarias, con la tasa de incidencia de un 66,34%; las infecciones hospitalarias del trato urinario presentaron incidencia de un 22,11%, las de sitio quirúrgico un 5,76% y el sistema vascular un 1,92%. Entre las neumonías los Staphylococcus aureus presentaron una incidencia de un 15,94%; A. baumanii (13,76%), P. aeruginosa (9,42%). En las infecciones del trato urinario incidieron Candida sp. (32,60%), P. aeruginosa (32,60%), E. coli, (10,86%) y Enterobacter spp., (10,86%). Los resultados de los tests de susceptibilidad a los antimicrobianos mostraron que A. baumannii presentó una tasa de sensibilidad de un 69,07% para los carbapenens. Todas las muestras de S. aureus fueron sensibles a la vancomicina y un 34,5% fueron sensibles a la oxacilina. La tasa de incidencia de letalidad ocasionada por las infecciones hospitalarias fue del 27,88%.

Este estudo teve como objetivo caracterizar as infecções hospitalares no centro de terapia intensiva de um hospital de ensino na Região Norte do Paraná no período de junho de 2003 a junho de 2004. Foram registradas 1304 saídas de pacientes e, desse total, 208 pacientes apresentaram infecção hospitalar. A taxa de infecção hospitalar foi de 15,95%. Staphylococcus aureus foi o microrganismo mais isolado, com incidência de 12,98%, seguido de Pseudomonas aeruginosa,12,50%, Acinetobacter baumannii, 9,61%; outros microrganismos apresentaram percentuais inferiores. Com relação à topografia das infecções hospitalares, a pneumonia apresentou maior incidência, com taxa de 66,34%. As infecções do trato urinário apresentaram incidência de 22,11%, as de sítio cirúrgico, 5,76%, e as do sistema vascular, 1,92%. Entre as pneumonias, S. aureus apresentou uma incidência de 15,94%; A. baumannii, de 13,76%; P. aeruginosa, de 9,42%. Nas infecções urinárias incidiram Candida sp. (32,60%), P. aeruginosa (32,60%), Escherichia coli (10,86%) e Enterobacter sp. (10,86%). Os resultados dos testes de susceptibilidade aos antimicrobianos mostraram que A. baumannii apresentou uma taxa média de sensibilidade de 69,07% para os carbapenens. Todas as amostras de S. aureus foram sensíveis à vancomicina e 34,5% foram sensíveis à oxacilina. A taxa de incidência de letalidade devido às infecções hospitalares foi de 27,88%.

The cell surface hydrophobicity and adhesion to abiotic and cellular surfaces was tested in five clinical strains of Acinetobacter baumannii isolated from catheter tips. Biochemical and molecular characteristics of these strains were also studied. Hydrophobicity was characterized by a test for affinity to xylene. Adhesion to abiotic surfaces (polystyrene, formica, latex and glass) was evaluated in Petri plates using the stamp technique. Buccal epithelial cells were used for tests of adhesion to cellular surfaces. Adhesion to the catheter was evaluated by repeatedly rinsing the catheters and rolling them over nutrient agar. Molecular typing of the strains was done by the ERIC-PCR technique. The degree of hydrophobicity of the strains varied from hydrophobic to hydrophilic. All the strains adhered to the cell surfaces and to the catheters, and three of them strongly adhered to latex, polystyrene and formica. Catheter adhesion was reduced by meropenem. We found a direct relationship between the degree of bacterial hydrophobicity and adhesion to the abiotic surfaces, but not with adhesion to cellular surfaces, which suggests that different mechanisms are involved in adherence.

Bactérias produtoras de betalactamase de espectro estendido (ESBL) representam um dos mais importantes problemas de resistência bacteriana nos hospitais brasileiros. A necessidade da implementação de testes que apresentem alta acurácia e baixo custo é de suma importância devido à dificuldade na detecção de ESBL. O objetivo do presente estudo foi avaliar a acurácia dos testes de adição de ácido clavulânico comercializados pela Oxoid® (Basingstoke, Inglaterra) e do Etest ESBL Screen® (AB Biodisk, Solna, Suécia) para detecção de K. pneumoniae produtoras de ESBL. Objetivamos também avaliar comparativamente a sensibilidade e a especificidade dos substratos betalactâmicos utilizados nestas metodologias. Foram avaliadas 134 amostras de K. pneumoniae isoladas em hemocultura de pacientes internados no Hospital São Paulo no período de julho de 1996 a julho de 2001. As amostras foram avaliadas quanto à produção de ESBL pelo teste de triagem preconizado pelo National Committee for Clinical Laboratory Standards (NCCLS), adição de ácido clavulânico (Oxoid®) e Etest ESBL Screen®. Foram consideradas produtoras de ESBL (padrão-ouro) amostras que apresentaram teste de triagem positivo e pelo menos um dos dois testes avaliados também positivo. O teste de adição de ácido clavulânico (Oxoid®) apresentou 100% de sensibilidade e 100% de especificidade, e os substratos que apresentaram melhor desempenho neste teste foram cefotaxima e cefpodoxima, ambos com 100% de sensibilidade e especificidade. O Etest ESBL Screen® apresentou 96% de sensibilidade e 100% de especificidade, sendo que a cefotaxima mostrou novamente melhor desempenho, com 92,5% de sensibilidade e 100% de especificidade. O teste de adição de ácido clavulânico (Oxoid®) apresentou excelente desempenho e pode ser facilmente implementado na rotina laboratorial por ser de alta acurácia e de fáceis realização e interpretação.

Bacterial strains producing extended spectrum beta-lactamases (ESBL) represent a common resistance problem among Brazilian hospitals. Due to the difficulty of ESBL detection in the clinical laboratory, these bacterial isolates require a reproducible, efficient, and low cost detection method. The aim of the present study was to evaluate the efficacy of detection of K. pneumoniae ESBL isolates by two methods: the Etest ESBL strip and the inhibitor potentiated disk diffusion test with clavulanic acid (clavulanate-potentiation test). The sensitivity and the specificity of beta-lactam agents against these isolates were also evaluated. The experiments were performed on a total of 134 K. pneumoniae isolates recovered from blood specimens in our institution from July 1996 to July 2001. The samples were tested for ESBL production by the NCCLS screen test, clavulanate-potentiation test and Etest ESBL strip. Isolates presenting positive results for the screen test and for at least one of the evaluated tests were considered ESBL producers (gold standard). The results of this study yielded a 100% specificity and sensitivity for the clavulanate-potentiation test, and the best indicators of ESBL production were cefotaxime and cefpodoxime. The Etest ESBL strip also turned out to be a very sensitive (96%) and specific (100%) method, being cefotaxime the most efficient substrate. According to the results of this investigation, the clavulanate potentiation disk diffusion test displayed an excellent performance and can be easily implemented in routine clinical laboratories as a practical, reliable, and accurate method.

Durante um surto ocorrido de abril a setembro de 1994 em um Hospital Universitário, dezesseis cepas de Acinetobacter baumannii foram isoladas de pacientes e uma de solução enteral. Nós posteriormente analizamos as cepas isoladas durante o surto pelos seguintes métodos de tipagem : perfil de DNA plasmidial, perfil de antibiograma e biotipagem. Dois padrões de tipagem foram identificados pela análise do perfil plasmidial. Doze cepas foram caracterizadas como sendo do biotipo 2, e cinco do biotipo 19. O padrão de sensibilidade a amicacina e a carbenicilina possibilitou a classificação das cepas em dois grupos. Os resultados demonstraram que estes três métodos de tipagem associados possibilitaram a diferenciação do que primeiramente foi considerado como um único surto, em dois surtos aparentemente não relacionados.

During an outbreak at an University Hospital, from April to September, in 1994, sixteen strains of Acinetobacter baumannii were isolated from patients and one strain from an enteral solution. We afterwards analyzed the outbreak by means of plasmid typing, antibiotic resistance typing and biotyping. Two main plasmid profiles were identified. Twelve strains belonged to biotype 2, and five to biotype 19. Susceptibility to amikacin and to carbenicillin allowed classification of the strains into two groups. The results show that association of those three typing methods allowed the differentiation of what was at first considered as a single outbreak into two apparently unrelated outbreaks.