Subchronic co-exposure to particulate matter and fructose-rich-diet induces insulin resistance in male Sprague Dawley rats.

Insulin resistance (IR) and metabolic disorders are non-pulmonary adverse effects induced by fine particulate matter (PM2.5) exposure. The worldwide pandemic of high fructose sweeteners and fat rich modern diets, also contribute to IR development. We investigated some of the underlying effects of IR, altered biochemical insulin action and Insulin/AKT pathway biomarkers. Male Sprague Dawley rats were subchronically exposed to filtered air, PM2.5, a fructose rich diet (FRD), or PM2.5 + FRD. Exposure to PM2.5 or FRD alone did not induce metabolic changes. However, PM2.5 + FRD induced leptin release, systemic hyperinsulinemia, and Insulin/AKT dysregulation in insulin-sensitive tissues preceded by altered AT1R levels. Histological damage and increased HOMA-IR were also observed from PM2.5 + FRD co-exposure. Our results indicate that the concomitant exposure to a ubiquitous environmental pollutant, such as PM2.5, and a metabolic disease risk factor, a FRD, can contribute to the metabolic disorder pandemic occurring in highly polluted locations.

Wood Smoke Extract Promotes Extracellular Matrix Remodeling in Normal Human Lung Fibroblasts.

Wood smoke (WS) contains many harmful compounds, including polycyclic aromatic hydrocarbons (PAHs). WS induces inflammation in the airways and lungs and can lead to the development of various acute and chronic respiratory diseases. Pulmonary fibroblasts are the main cells involved in the remodeling of the extracellular matrix (ECM) during the WS-induced inflammatory response. Although fibroblasts remain in a low proliferation state under physiological conditions, they actively participate in ECM remodeling during the inflammatory response in pathophysiological states. Consequently, we used normal human lung fibroblasts (NHLFs) to assess the potential effects of the PAHs-containing wood smoke extract (WSE) on the growth rate, total collagen synthesis, and the expression levels of collagen I and III, matrix metalloproteinase (MMP)-1, MMP-2, MMP-9, tissue inhibitor of metalloproteinase (TIMP)-1, TIMP-2, and the transforming growth factor (TGF)-ß1. We also assessed MMPs activity. The results showed that WSE induced a trimodal behavior in the growth rate curves in NHLFs; the growth rate increased with 0.5-1 % WSE and decreased with 2.5% WSE, without causing cell damage; 5-20% WSE inhibited the growth and induced cell damage. After 3 hours of exposure, 2.5% WSE induced an increase in total collagen synthesis and upregulation of TGF-ß1, collagen I and III, MMP-1, TIMP-1, and TIMP-2 expression. However, MMP-2 expression was downregulated and MMP-9 was not expressed. The gelatinase activity of MMP-2 was also increased. These results suggest that WSE affects the ECM remodeling in NHLFs and indicate the potential involvement of PAHs in this process.

Current situation of polycyclic aromatic hydrocarbons (PAH) in PM2.5 in a receptor site in Mexico City and estimation of carcinogenic PAH by combining non-real-time and real-time measurement techniques.

Air pollution is a public health concern. Polycyclic aromatic hydrocarbons (PAH) are ubiquitous atmospheric pollutants contained in the atmospheric aerosol. PAH in particulate matter with diameters ≤2.5 µm (PM2.5) represent a human health risk due to their toxic properties. In this study, PAH in PM2.5 at a receptor site of Mexico City during the dry cold season were determined. The most abundant PAH (median, 10-90th percentile, pg m-3) were benzo[ghi]perylene (467, 291-697), followed by pyrene (427, 218-642). A decrease around 40% in the carcinogenic PAH onto PM2.5 was calculated with respect to the same PAH measured a decade ago, at the same receptor site, despite of increase in vehicle fleet. The PAH decrease trend agrees with the decrease trend of CO, NO and NO2, released into the air by similar emission sources than PAH. Control emissions strategies implemented by local and federal authorities are discussed. PAH analyses were carried out by non-real-time and real-time methods. The PAH non-real-time method involved PM2.5 sampling, sample treatment and gas chromatography-mass spectrometry analysis. The PAH real-time method involved the use of a photoelectric aerosol sensor (PAS). The PAH determination by non-real time method was selective and efficient, with recoveries between 75 ±â€¯14% and 98 ±â€¯26%. By combining non-real-time and real-time methodologies, multivariate regression models were obtained based on PAS response, NO2 and wind speed to estimate PAH in PM2.5 at low-cost (r2 = 0.59 to r2 = 0.89). Fossil fuel combustion from vehicles was the major source around the sampling site. Diagnostic ratios (DR) based on retene, chrysene, and triphenylene, suggested biomass burning emission sources. Photo-oxidation in sunny months was observed based on benzo[a]pyrene, benzo[ghi]perylene, benz[a]anthracene, indeno[1,2,3-cd]pyrene and black carbon. The correlation analyses suggested transport of PM2.5, O3, BC and SO2 to the sampling site, and local emissions of PAH, NO and CO.

Determinación de límites de referencia de analitos hematológicos en cabras lecheras adultas en el Altiplano Mexicano / Hematological analyte reference limits in adult dairy goats

RESUMEN Con el objetivo de establecer los límites de referencia de analitos hematológicos de cabras adultas de razas productoras de leche clínicamente sanas, sujetas al manejo y a las características de los sistemas de producción intensiva del Altiplano Mexicano, se recolectaron y analizaron muestras de sangre de cabras de 2 o más años de edad en diferentes etapas de producción. Con los resultados se obtuvieron los límites de referencia para hematocrito, cuenta de eritrocitos, volumen globular medio (VGM), plaquetas, sólidos totales, fibrinógeno, cuenta de leucocitos, neutrófilos segmentados, neutrófilos en banda, linfocitos, monocitos, eosinófilos y basófilos. Las medias obtenidas para cada analito fueron: hematocrito (0,22-0,36 L/L), cuenta de eritrocitos (9,07-18,47 x1012/L), volumen globular medio (VGM) (14,44-27,91), plaquetas (229-3 1 63 x109/L), solidos totales (65,64-84,64 g/L), fibrinógeno (0-6 g/L), cuenta de leucocitos (3,75-11,47 x109/L), neutrófilos segmentados (0,95-4,98 x109/L), neutrófilos en banda (0-0,16 x109/L), linfocitos (1,76-6,44 x109/L), monocitos (0-0,65 x109/L), eosinófilos (0-1,36 x109/L) y basófilos (0 - 0,37 x109/L). Estos valores se compararon con los obtenidos en otros estudios similares, y se encontraron algunas diferencias mayoritariamente en los valores obtenidos para hematocrito, eritrocitos, VGM, plaquetas, leucocitos y linfocitos, lo cual se debe a las diferencias en condiciones medioambientales y de alimientación entre los estudios.

ABSTRACT With the aim to establish the hematological analyte reference limits of clinically healthy adult goats of dairy producing breeds, subjected to the handling and characteristics of intensive production systems in the Mexican Plateau, the blood samples of 2-year old and older goats at different production stages were collected and analyzed. Reference limits (interval in brackets) for hematocrit (0.22-0.36 L/L), erythrocyte count (9.07-18.47 x1012/L), mean cell volume (MCV) (14.44-27.91 fL), platelets (229-3163 x109/L), total solids (65.64-84.64 g/L), fibrinogen (0-6 g/L), leukocyte count (3.75-11.47 x109/L), segmented neutrophils (0.95-4.98 x109/L), band neutrophils (0-0.16 x109/L), lymphocytes (1.76-6.44 x109/L), monocytes (0-0.65 x109/L), eosinophils (0-1.36 x109/L) and basophils (0-0.37 x109/L) were obtained. These values were compared with similar study results. Differences were found mainly in the values for hematocrit, erythrocytes, MCV, platelets, total leukocytes, and lymphocytes; this is due to environmental and feeding differences between the studies.

Successful management of multidrug-resistant tuberculosis under programme conditions in the Dominican Republic.

SETTING: The Dominican Republic is a high-incidence area for multidrug-resistant tuberculosis (MDR-TB; 6.6% of initial cases). Standardised treatment regimens for MDR-TB may be a potential solution. OBJECTIVE: To present the effectiveness of standard regimens under routine national conditions. DESIGN: We reviewed all MDR-TB patients treated under routine conditions from 29 August 2006 to 30 June 2010, showing interim and final outcomes. Patients were treated with regimens that were standardised or individualised based on previously received second-line anti-tuberculosis drugs. RESULTS: Population description and culture conversion data are reported for the 289 MDR-TB patients. The median patient age was 31 years. Most had failed first-line treatment (72.6%). Culture negativity was obtained within 4 months (median 2 months) in 78.6%. Among the 150 patients treated between 2006 and 2008, 74% had favourable results on standardised and 66% on individualised regimens (P = 0.211). The efficacy of the standardised and individualised regimens was respectively 92.8% and 81% (P = 0.056). The relapse rate was approximately 1%. A median of five drug side effects occurred per patient. More than 2 months to culture conversion and bilateral cavitation on chest X-ray were found to be unfavourable outcome risk factors. CONCLUSIONS: Standardised MDR-TB regimens may be effective at the national level, even in resource-poor settings.

Caracterización clínica y molecular de bacteriemias causadas por enterobacterias productoras de β -lactamasas de espectro extendido: 2004-2007 / Clinical and molecular characterization of ESBL-producing enterobacteria isolated from bacteremia in a university hospital

Introduction: Extended-spectrum-β-lactamases (ESBL) are plasmid-encoded enzymes that confer resistance to multiple antimicrobials. ESBL-producing enterobacteria that cause bacteremia limit therapeutic options and increase mortality. Objective: To perform a clinical and molecular description of bacteremia caused by ESBL-producing enterobacteria. Method: We retrospectively studied the cases of bacteremia due to ESBL-producing Escherichia coli, Klebsiella pneumoniae and Proteus spp in adults admitted to a university hospital during the years 2004-2007. We reviewed the clinical records and antimicrobial susceptibility patterns. Molecular typing was performed by polymerase chain reaction and study of clonality by pulsed-field electrophoresis. Results: We found a prevalence of 9.8 percent ESBL in enterobacteria causing bacteremia. Decreased susceptibility to quinolones and aminoglycosides was observed, without resistance to carbapenems. The predominant ESBL types were CTX-M (96 percent), TEM (62 percent) and GES (28 percent). 79 percent of the strains presented more than one type of ESBL. Clinical analysis revealed high prevalence of risk factors, previous use of antimicrobials and of invasive devices. There was no significant clonality. Conclusion: The presence of ESBLs in bloodstream infections is a clinical problem that must be considered when choosing empiric therapy.

Introducción: β-lactamasas de espectro extendido (BLEE) son enzimas plasmidiales que confieren resistencia a múltiples antimicrobianos. Las bacteriemias por enterobacterias productoras de BLEE restringen las opciones terapéuticas y aumentan la mortalidad. Objetivo: Realizar una descripción clínica y molecular de las bacteriemias causadas por enterobacterias productoras de BLEE. Método: Se estudiaron retrospectivamente los casos de bacteriemia por Escherichia coli, Klebsiella pneumoniae y Proteus spp. confirmadas para BLEE, en adultos ingresados en un hospital universitario durante los años 2004-2007. Se revisaron los registros clínicos y de susceptibilidad. Se realizó tipificación molecular por reacción de polimerasa en cadena y estudio de clonalidad por electroforesis de campo pulsado. Resultados: Se identificó una prevalencia de BLEE de 9,8 por ciento en enterobacterias causantes de bacteriemias. Se observó susceptibilidad disminuida a quinolonas y aminoglucósidos, sin resistencia a carbapenémicos. Los tipos de BLEE predominantes fueron CTX-M (96 por ciento), TEM (62 por ciento) y GES (28 por ciento). El 79 por ciento de las cepas presentó más de un tipo de BLEE. El análisis clínico reveló alta frecuencia de patologías de riesgo, uso previo de antimicrobianos y uso de dispositivos invasores. No se encontró clonalidad significativa. Conclusión: La presencia de BLEE en bacteriemias constituye un problema clínico que debe ser considerado al elegir la terapia empírica.

[Clinical and molecular characterization of ESBL-producing enterobacteria isolated from bacteremia in a university hospital]. / Caracterización clínica y molecular de bacteriemias causadas por enterobacterias productoras de β -lactamasas de espectro extendido: 2004-2007.

INTRODUCTION: Extended-spectrum-ß-lactamases (ESBL) are plasmid-encoded enzymes that confer resistance to multiple antimicrobials. ESBL-producing enterobacteria that cause bacteremia limit therapeutic options and increase mortality. OBJECTIVE: To perform a clinical and molecular description of bacteremia caused by ESBL-producing enterobacteria. METHOD: We retrospectively studied the cases of bacteremia due to ESBL-producing Escherichia coli, Klebsiella pneumoniae and Proteus spp in adults admitted to a university hospital during the years 2004-2007. We reviewed the clinical records and antimicrobial susceptibility patterns. Molecular typing was performed by polymerase chain reaction and study of clonality by pulsed-field electrophoresis. RESULTS: We found a prevalence of 9.8% ESBL in enterobacteria causing bacteremia. Decreased susceptibility to quinolones and aminoglycosides was observed, without resistance to carbapenems. The predominant ESBL types were CTX-M (96%), TEM (62%) and GES (28%). 79% of the strains presented more than one type of ESBL. Clinical analysis revealed high prevalence of risk factors, previous use of antimicrobials and of invasive devices. There was no significant clonality. CONCLUSION: The presence of ESBLs in bloodstream infections is a clinical problem that must be considered when choosing empiric therapy.

[Antimicrobial susceptibility, capsular serotypes and clonal relationship of invasive streptococcus pneumoniae isolates in adult population of the Bio-Bio region, Chile. 2005-2006]. / Susceptibilidad antimicrobiana, serotipos capsulares y relación clonal entre cepas invasoras de streptococcus pneumoniae aisladas de pacientes adultos de la Región del Bío-Bío, Chile. Periodo 2005-2006.

Streptococcus pneumoniae infections constitute a public health problem. In our country there is scarce information regarding isolates from bacteraemic episodes in adult population. The antibiotic susceptibility, serotypes and clonal relationship of 56 isolates of S. pneumoniae from adult patients with bacteraemic infections in Concepcion-Talcahuano, Bio-Bio Region, Chile, were studied. Resistance to tetracycline (21.4%), trimethoprim/ sulfamethoxazole (18%), erythromycin (18%), chloramphenicol (7%) and 1 penicillin resistant isolate from a meningeal focus (2%) was found. Also, all the isolates were susceptible to cefotaxime, levofloxacin, moxifloxacin and vancomycin. A wide variety of capsular serotypes was demonstrated, with predominance of serotypes 1, 5, 23F, 7F and 3. The macrorestriction analysis by pulse field electrophoresis revealed 31 electrophoretic patterns and 12 clonal groups, discarding a predominant clone. According to the results, at least, 80% of the S. pneumoniae serotypes isolated from bacteraemic adult patients are included in the available commercial vaccine.

Susceptibilidad antimicrobiana, serotipos capsulares y relación clonal entre cepas invasoras de Streptococcus pneumoniae aisladas de pacientes adultos de la Región del Bío-Bío, Chile: Período 2005-2006 / Antimicrobial susceptibility, capsular serotypes and clonal relationship of invasive Streptococcus pneumoniae isolates in adult population of the Bio-Bio Region, Chile: 2005-2006

Las infecciones ocasionadas por Streptococcus pneumoniae constituyen un problema de salud pública. En nuestro país existe escasa información sobre aislados de procesos bacteriémicos en población adulta. Se estudió la susceptibilidad, serotipos y relación clonal de 56 aislados de S. pneumoniae desde hemocultivos, entre enero 2005 y agosto 2006, de pacientes adultos de la intercomuna Concepción-Talcahuano, Región del Bío-Bío, Chile. Se encontró resistencia a tetraciclina (21,4 por ciento), cotrimoxazol (18 por ciento), eritromicina (18 por ciento), cloranfenicol (7 por ciento) y a penicilina en un solo aislado procedente de un foco meníngeo (2 por ciento). La totalidad mostró susceptibilidad a cefotaxima, levofloxacina, moxifloxacina y vancomicina. Se demostró una amplia variedad de serotipos capsulares, con predominio de los serotipos 1, 5, 23F, 7F y 3. El análisis de macrorestricción y electroforesis en campo pulsado reveló 31 patrones electroforéticos con 12 grupos clona-les, descartando un clon predominante. De acuerdo a los resultados, al menos 80 por ciento de los serotipos de aislados de S. pneumoniae de procesos bacteriémicos están incluidos en la vacuna comercial disponible.

Streptococcus pneumoniae infections constitute a public health problem. In our country there is scarce information regarding isolates from bacteraemic episodes in adult population. The antibiotic susceptibility, sero-types and clonal relationship of 56 isolates of S. pneumoniae from adult patients with bacteraemic infections in Concepcion-Talcahuano, Bio-Bio Region, Chile, were studied. Resistance to tetracycline (21.4 percent), trimethoprim/ sulfamethoxazole (18 percent), erythromycin (18 percent), chloramphenicol (7 percent) and 1 penicillin resistant isolate from a meningeal focus (2 percent) was found. Also, all the isolates were susceptible to cefotaxime, levofloxacin, moxifloxacin and vancomycin. A wide variety of capsular serotypes was demonstrated, with predominance of serotypes 1, 5, 23F, 7F and 3. The macrorestriction analysis by pulse field electrophoresis revealed 31 electrophoretic patterns and 12 clonal groups, discarding a predominant clone. According to the results, at least, 80 percent of the S. pneumoniae serotypes isolated from bacteraemic adult patients are included in the available commercial vaccine.

Bombas de expulsión multidrogas en Acinetobacter baumannii y resistencia a antimicrobianos / Multi-drug efflux pumps and antibiotic resistance in Acinetobacter baumannii

Los sistemas multidrogas bacterianos contribuyen al desarrollo del fenotipo de multi-resistencia presentado por cepas de Acinetobacter baumannü, patógeno intrahospi-talario, que durante los últimos años ha incrementado su importancia por la creciente resistencia a carbapenémicos. El fenotipo de multi-resistencia está otorgado por la combinación de varios mecanismos de resistencia entre los cuales se encuentran estos sistemas de bombas de expulsión. El sistema multidroga AdeABC se ha detectado en muchas de estas cepas multi-resistentes de A. baumannü y, se ha relacionado con resistencia a diversos grupos de antimicrobianos, incluidos tigeciclina y meropenem. La inhibición de dichos sistemas multidrogas permitiría aumentar la eficacia de la terapia antimicrobiana. La siguiente revisión se enfoca en las bombas de expulsión multidrogas presentes en A. baumannü, con particular énfasis en el sistema AdeABC.

Bacterial multi-drugs systems contribute to the development of multi-resistance patterns of Acinetobacter baumannii, a nosocomial pathogen of increasing importance due to its emerging resistance to carbapenems. The multi-resistance phenomena is generated by a combination of mechanisms, one of which the efflux pump system. Many of these multiresistant isolates of A. baumannii harbor genes for the AdeABC multi-drug efflux system, related with resistance to various groups of antibacterial agents, including tygecicline and meropenem. Inhibition of these systems would allow to increase the efficacy of this antimicrobial. This review focuses on the multi-drug efflux pump system oí A. baumanni with special emphasis in the AdeABC system.

RNA silencing gene truncation in the filamentous fungus Aspergillus nidulans.

The genus Aspergillus is ideally suited for the investigation of RNA silencing evolution because it includes species that have experienced a variety of RNA silencing gene changes. Our work on this subject begins here with the model species Aspergillus nidulans. Filamentous ascomycete fungi generally each encode two of the core RNA silencing proteins, Dicer and Argonaute, but A. nidulans appears to have lost one of each to gene truncation events. Although a role in growth, development, or RNA silencing was not detected for the truncated genes, they do produce spliced and poly(A)-tailed transcripts, suggesting that they may have an undetermined biological function. Population analysis demonstrates that the truncated genes are fixed at the species level and that their full-length orthologs in a closely related species are also unstable. With these gene truncation events, A. nidulans encodes only a single intact Dicer and Argonaute. Their deletion results in morphologically and reproductively normal strains that are incapable of experimental RNA silencing. Thus, our results suggest that the remaining A. nidulans RNA silencing genes have a "nonhousekeeping" function, such as defense against viruses and transposons.

[Mutations in gyrA and gyrB genes among strains of Gram-negative bacilli isolated from Chilean hospitals and their relation with resistance to fluoroquinolones]. / Mutaciones en genes gyrA y gyrB en cepas de bacilos Gram negativos aisladas en hospitales chilenos y su relación con la resistencia a fluoroquinolonas.

BACKGROUND: A progressive frequency of resistance to fluoroquinolones is observed among Gram-negative bacilli. AIM: To investigate the mechanism of resistance to fluoroquinolones mediated by mutations affecting gyrA and gyrB genes in strains of Gram negative bacüli isolated from CMean hospitals. MATERIAL AND METHOD: Minimal inhibitory concentration of fluoroquinolones was determined in 91 randomly selected nalidixic acid-resistant strains of Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa, isolated from hospitals of 12 Chilean cities. Quinolone resistance determining region (QRDR) was amplified by PCR and mutations were determined by restriction fragment length polymorphism (RFLP) and DNA sequencing. RESULTS: Strains with mutation in codon 83 of gyrA showed decreased susceptibility to ciprofloxacin with MICs ranging from 0.25 to 1024 fig/ml. The sequencing of PCR products for gyrA indicated amino acid changes in the QRDR region. One strain ofE. coli presented a double mutation, in codon 83 Ser to Leu as well as in codon 87 Asp to Asn. In strains ofK. pneumoniae, however, the change of codon 83 was Ser to Tyr, in A. baumannii was Ser to Leu and in P. aeruginosa was Thr to He. No strains with mutations affecting gyrB were found. CONCLUSIONS: Mutations in codon 83 of gyrA is a frequent genetic event involved in the mechanism leading to decreased susceptibility to fluoroquinolone in strains of Gram-negative bacilli.

Mutaciones en genes gyrA y gyrB en cepas de bacilos Gram negativos aisladas en hospitales chilenos y su relación con la resistencia a fluoroquinolonas / Mutations in gyrA and gyrB genes among strains of Gram-negative bacilli isolated from Chilean hospitals and their relation with resistance to fluoroquinolones

Background: A progressive frequency of resistance to fluorquinolones is observed among Gram-negative bacilli. Aim: To investigate the mechanism of resistance to fluoroquinolones mediated by mutations affecting gyrA and gyrB genes in strains of Gram negative bacüli isolated from CMean hospitals. Material and method: Minimal inhibitory concentration of fluoroquinolones was determined in 91 randomly selected nalidixic acid-resistant strains of Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa, isolated from hospitals of 12 Chilean cities. Quinolone resistance determining region (QRDR) was amplified by PCR and mutations were determined by restriction fragment length polymorphism (RFLP) and DNA sequencing. Results: Strains with mutation in codon 83 of gyrA showed decreased susceptibility to ciprofloxacin with MICs ranging from 0.25 to 1024 fig/ml. The sequencing of PCR products for gyrA indicated amino acid changes in the QRDR region. One strain ofE. coli presented a double mutation, in codon 83 Ser to Leu as well as in codon 87 Asp to Asn. In strains ofK. pneumoniae, however, the change of codon 83 was Ser to Tyr, in A. baumannii was Ser to Leu and in P. aeruginosa was Thr to He. No strains with mutations affecting gyrB were found. Conclusions: Mutations in codon 83 of gyrA is a frequent genetic event involved in the mechanism leading to decreased susceptibility to fluoroquinolone in strains of Gram-negative bacilli.

Identificación molecular de enzimas modificantes de aminoglucósidos en cepas de Enterococcus spp. aisladas en hospitales de la Octava Región de Chile / Molecular identification of aminoglycoside-modifying enzymes among strains of Enterococcus spp. isolated in hospitals of the VIII Region of Chile

Background: Infectious diseases produced by Enterococcus spp, must be treated with a synergistic combination between a penicillin and an aminoglycoside. High level resistance to aminoglycosides is a serious therapeutic problem, since it predicts the loss of synergistic activity of this antimicrobial combination. Aim: To investigate the presence of genes encoding aminoglycoside-modifying enzymes (AMEs) among strains of Enterococcus spp with high level of resistance to aminoglycosides. Material and methods: The genes encoding some of the AMEs were investigated among 305 aminoglycoside-resistant strains of Enterococcus spp isolated in hospitals of the VIII region of Chile, by dot blot hybridization and Polymerase Chain Reaction (PCS). Results: High level resistance to some aminoglycosides was observed in 104 strains (34.1 percent) and 93 of these harbored at íeast one of the genes encoding the investigated AMEs. Three genes were detected: aac(6)Ie-aph(2")Ia (14.8 percent) encoding for the enzyme AAC(6)Ie-APH(2")Ia (resistance to all aminoglycosides, except streptomycin); aph(3)IIIa (26 percent), and ant(6)la (28.5 percent) encoding for the phosphorylating enzymes APH(3)Ilia (resistance to kanamycin, amikacin and neomycin), and ANT(6)-la (resistance only to streptomycin), respectively. None of the strains harbored the gene ant (4) which encode for the enzyme ANT (4). Conclusion: The low frequency of strains harbouring the bifunctional enzyme (<15 percent), conferring an extended resistance profile to aminoglycosides, allows us to propose the empirical use of aminoglycoside-aminocyclitols, associated to a penicillin, in the treatment of serious infections produced by species of enterococci.

[Extended spectrum beta lactamases (ESBL) production in Acinetobacter baumannii strains isolated from Chilean hospitals belonging to VIII Region]. / Producción de beta-lactamasas de espectro extendido (BLEE) en cepas de Acinetobacter baumannii aisladas en hospitales de la VIIIa Región, Chile.

The resistance of Acinetobacter baumannii to ss-lactam antibiotics is mainly due to the synthesis of ss-lactamases. From a clinical point of view, this bacteria and others, grouped under the acronym SPACE (S: Serratia, P: Pseudomonas, A: Acinetobacter, C: Citrobacter, E: Enterobacter) are essentially Amp-C ss-lactamases producers. There is no local information about ESBL presence in Acinetobacter. We studied ESBL production using the Ho and col. technique modified by adding cloxacillin as chromosomal ss-lactamases inhibitor. From 69 isolates, with resistance to at least one third generation cephalosporin, only 7 showed positive synergy test. Four of these amplified for TEM family gene, and one of these amplified also for the OXA family. Our study found a low ESBL production percentage, which agrees with the premise of Amp-C as the main mechanism of resistance to ss-lactam antibiotics in A. baumannii. However, the ESBL description in these bacteria emphasizes the capacity of expressing multiple resistance mechanisms.

Producción de ß-lactamasas de espectro extendido (BLEE) en cepas de Acinetobacter baumannii aisladas en hospitales de la VIIIª Región, Chile / Extended spectrum ß-lactamases (ESBL) production in Acinetobacter baumannii strains isolated from Chilean hospitals belonging to VIII Region

The resistance of Acinetobacter baumannii to ß-lactam antibiotics is mainly due to the synthesis of ß-lactamases. From a clinical point of view, this bacteria and others, grouped under the acronym SPACE (S: Serratia, P: Pseudomonas, A: Acinetobacter, C: Citrobacter, E: Enterobacter) are essentially Amp-C ß-lactamases producers. There is no local information about ESBL presence in Acinetobacter. We studied ESBL production using the Ho and col. technique modified by adding cloxacillin as chromosomal ß-lactamases inhibitor. From 69 isolates, with resistance to at least one third generation cephalosporin, only 7 showed positive synergy test. Four of these amplified for TEM family gene, and one of these amplified also for the OXA family. Our study found a low ESBL production percentage, which agrees with the premise of Amp-C as the main mechanism of resistance to ß-lactam antibiotics in A. baumannii. However, the ESBL description in these bacteria emphasizes the capacity of expressing multiple resistance mechanisms.

La resistencia de Acinetobacter baumannii a antimicrobianos ß-lactámicos se debe fundamentalmente a la síntesis de ß-lactamasas. Del punto de vista clínico se considera que esta bacteria, y otras agrupadas en el acrónimo SPACE (Serratia, Pseudomonas, Acinetobacter, Citrobacter, Enterobacter), son predominantemente productoras de ß-lactamasas tipo AmpC. No hay información en nuestro país sobre presencia de ß-lactamasas de espectro extendido (BLEE) en Acinetobacter. Se estudió la producción de BLEE en cepas de Acinetobacter, mediante una modificación de la técnica de Ho y col adicionando cloxacilina como inhibidor de ß-lactamasas cromosomales. De 69 cepas con resistencia al menos a una cefalosporina de tercera generación, sólo siete presentaron sinergia positiva. Cuatro cepas amplificaron por RPC un fragmento intragénico de genes de familia TEM y una de ellas amplificó, además, para el gen de la familia OXA. Se evidenció un bajo porcentaje de producción de BLEE, lo que confirma que la producción de Amp-C es el principal mecanismo de resistencia de A. baumannii a ß-lactámicos. Sin embargo, la descripción de BLEE en esta bacteria, enfatiza su capacidad de albergar múltiples mecanismos de resistencia.