RESUMEN
Sea chub, Girella laevifrons, is a coastal fish that inhabits high intertidal rockpools along the coast of Chile. The intertidal pools where the juveniles live, are an extreme environment with high levels of ultraviolet (UV) radiation, becoming harmful to the organisms, due to oxidative stress generated by reactive oxygen species. For this reason organisms develop adaptations that allow them to survive in this complex environment. The search of biomonitor species, sensitive to UV radiation is very important in aquatic ecosystems, mainly in the southern hemisphere where depletion of the ozone layer and the consequent increase of UV radiation, have become an environmental problem. The aim of this study was to evaluate the effect of ultraviolet radiation in G. laevifrons and its possible use as UV-B radiation biomonitor specie in intertidal systems, which are very important for the Chilean fisheries. The effect of UV radiation exposure on juvenile G. laevifrons was measured through oxidative stress parameters. Catalase's activity increased with the time of exposure, unlike superoxide dismutase's activity which peaked at 2h, decreasing towards the 5th hour of irradiation. The superoxide dismutase activity in muscle tissue did not show significant differences. The lipid peroxidation and DNA damage increased in relation to exposition times. Tissue muscle's DNA damage was shown only at 5h of exposure. Significant differences between the two organs in the antioxidant capacity were observed, the liver of G. laevifrons exhibited the higher antioxidant capacity. It can be concluded that this specie exhibits effective protection mechanisms against UV radiation exposure and it is not appropriate specie as a biomonitor in intertidal systems.
Asunto(s)
Ambiente , Peces/fisiología , Estrés Oxidativo/efectos de la radiación , Rayos Ultravioleta , Adaptación Fisiológica/efectos de la radiación , Animales , Antioxidantes/metabolismo , Chile , Daño del ADN/efectos de la radiación , Peces/genética , Peces/metabolismo , Humanos , Peroxidación de Lípido/efectos de la radiación , Oxidación-Reducción , Especies Reactivas de Oxígeno , TemperaturaRESUMEN
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.
Asunto(s)
Antibacterianos/uso terapéutico , Farmacorresistencia Bacteriana Múltiple/efectos de los fármacos , Infecciones Neumocócicas/tratamiento farmacológico , Streptococcus pneumoniae/efectos de los fármacos , Adolescente , Adulto , Chile/epidemiología , Cloranfenicol/uso terapéutico , Electroforesis en Gel de Campo Pulsado , Eritromicina/uso terapéutico , Femenino , Humanos , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Infecciones Neumocócicas/epidemiología , Serotipificación , Streptococcus pneumoniae/clasificación , Tetraciclina/uso terapéutico , Combinación Trimetoprim y Sulfametoxazol/uso terapéutico , Adulto JovenAsunto(s)
Adolescente , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto Joven , Antibacterianos/uso terapéutico , Farmacorresistencia Bacteriana Múltiple/efectos de los fármacos , Infecciones Neumocócicas/tratamiento farmacológico , Streptococcus pneumoniae/efectos de los fármacos , Chile/epidemiología , Cloranfenicol/uso terapéutico , Electroforesis en Gel de Campo Pulsado , Eritromicina/uso terapéutico , Pruebas de Sensibilidad Microbiana , Infecciones Neumocócicas/epidemiología , Serotipificación , Streptococcus pneumoniae/clasificación , Tetraciclina/uso terapéutico , Combinación Trimetoprim y Sulfametoxazol/uso terapéutico , Adulto JovenRESUMEN
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.
Asunto(s)
Adolescente , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto Joven , Antibacterianos/uso terapéutico , Farmacorresistencia Bacteriana Múltiple/efectos de los fármacos , Infecciones Neumocócicas/tratamiento farmacológico , Streptococcus pneumoniae/efectos de los fármacos , Chile/epidemiología , Cloranfenicol/uso terapéutico , Electroforesis en Gel de Campo Pulsado , Eritromicina/uso terapéutico , Pruebas de Sensibilidad Microbiana , Infecciones Neumocócicas/epidemiología , Serotipificación , Streptococcus pneumoniae/clasificación , Tetraciclina/uso terapéutico , Combinación Trimetoprim y Sulfametoxazol/uso terapéutico , Adulto JovenRESUMEN
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.
Asunto(s)
Acinetobacter baumannii/metabolismo , Antibacterianos/farmacocinética , Proteínas Bacterianas/metabolismo , Farmacorresistencia Bacteriana Múltiple/fisiología , Proteínas de Transporte de Membrana/metabolismo , Acinetobacter baumannii/efectos de los fármacos , Antibacterianos/farmacologíaRESUMEN
Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disorder consisting of oculocutaneous albinism, platelet dysfunction and systemic complications associated with lipofuscin deposition in the reticuloendothelial system. HPS has been associated with a granulomatous enterocolitis with pathologic features suggestive of Crohn's disease. It remains uncertain if HPS represents a truly distinct form of granulomatous enterocolitis. We report a series of two patients with HPS treated in Puerto Rico, and the results from medical and surgical intervention for gastrointestinal disease. Our experience with HPS patients has shown the difficult management of perineal disease similar in the management of Crohn's. However, complications from the bleeding diathesis necessitate caution during surgery and potential anesthesia complications. Furthermore, avoidance of a perineal wound is preferred, and when possible, ileostomies have fewer complications than colostomies as they do not involve the small bowel.
Asunto(s)
Humanos , Adolescente , Proctocolitis/complicaciones , Síndrome de Hermanski-Pudlak/complicaciones , NiñoRESUMEN
BACKGROUND: Anorectal fistula is a common problem that affects quality of life. Main objective of therapy has been to eradicate the fistula tract while preserving fecal continence. Latest good results for anal fistula treatment have been an anal fistula plug. This study was undertaken to determine if these results could be reproduced in Puerto Rico. METHOD: From January 2003 to January 2008, two experienced colorectal surgeons performed this new operation in 23 consecutive patients. A multivariable analysis was undertaken including age, sex, location of the fistula, previous surgeries, Seton placement before the insertion of the plug, continence pre and post operation, as well as close follow up. No patient with inflammatory bowel disease was included. RESULTS: We had a good result or healing of the fistula in 14 of 23 patients for a success rate of 60%. We had a subgroup of patients who did slightly better and had a healing rate of 66% compared to the 60% of the whole group. It appears to be a trend in favor of the Seton group but is not statically significant. We had 9 failures of 23 patients or 39%. Suppuration was noticed in three patients and all three had failures of the plug with recurrences. CONCLUSIONS: This new operation is another alternative to add to our armamentarium but we need to search for an operation that decreases the incidence of recurrences we had in our study while maintaining function of the sphincters.
Asunto(s)
Humanos , Masculino , Femenino , Fístula Rectal/terapia , Diseño de Equipo , Puerto Rico , Estudios RetrospectivosRESUMEN
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.
Asunto(s)
Antibacterianos/farmacología , Proteínas Bacterianas/genética , Girasa de ADN/genética , Farmacorresistencia Bacteriana/genética , Fluoroquinolonas/farmacología , Bacterias Gramnegativas , Mutación/genética , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/genética , Chile , Codón/genética , Escherichia coli/efectos de los fármacos , Escherichia coli/genética , Frecuencia de los Genes , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Gramnegativas/genética , Hospitales , Humanos , Klebsiella pneumoniae/efectos de los fármacos , Klebsiella pneumoniae/genética , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/genéticaRESUMEN
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.
Asunto(s)
Humanos , Antibacterianos/farmacología , Proteínas Bacterianas/genética , Girasa de ADN/genética , Farmacorresistencia Bacteriana/genética , Fluoroquinolonas/farmacología , Bacterias Gramnegativas , Mutación/genética , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/genética , Chile , Codón/genética , Escherichia coli/efectos de los fármacos , Escherichia coli/genética , Frecuencia de los Genes , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Gramnegativas/genética , Hospitales , Klebsiella pneumoniae/efectos de los fármacos , Klebsiella pneumoniae/genética , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/genéticaRESUMEN
The increasing reporting of Streptococcus pneumoniae resistance to penicillin has lead to the recommendation of third generation cephalospirins for the treatment of serious pneumococcal infections. As a consequence, clinicians usually do not prescribe first line antibiotics despiste the availability of susceptibility studies. Whit the aim to evaluate the impact of the infectious diseases specialist evaluation in the apropriate use oh the susceptibility studies, two series were compared: a historic control one (1998-2002, n = 50) and a prospectuve group that had the advisement of one infectious diseases specialist (2003-2006, n = 60). In both series, pneumonia stood out as the source of the bacteremia, and -alcoholism/hepatic insufficiency as associated factor. In the first series, 48 isolates resulted susceptible to penicillin by agar diffusion, and 1 out of 36 patients with pneumonia had a change in the antibiotic therapy to penicillin. In the prospective series, we found 56 susceptible isolates, and the remaining four were classified as intermediate susceptibility according to the MIC value. Antibiotics were changed in 36 out of 50 patients with bacteremic pneumococcal pneumonia (p < 0.05). The infectious diseases specialist evaluation had a positive impact on the use of the microbiological information for therapeutics purposes.
Asunto(s)
Antibacterianos/uso terapéutico , Bacteriemia/tratamiento farmacológico , Neumonía Neumocócica/tratamiento farmacológico , Streptococcus pneumoniae/efectos de los fármacos , Adulto , Bacteriemia/microbiología , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Resistencia a las Penicilinas , Estudios ProspectivosRESUMEN
The increasing reporting of Streptococcus pneumoniae resistance to penicillin has lead to the recommendation of third generation cephalospirins for the treatment of serious pneumococcal infections. As a consequence, clinicians usually do not prescribe first line antibiotics despiste the availability of susceptibility studies. Whit the aim to evaluate the impact of the infectious diseases specialist evaluation in the apropriate use oh the susceptibility studies, two series were compared: a historic control one (1998-2002, n = 50) and a prospectuve group that had the advisement of one infectious diseases specialist (2003-2006, n = 60). In both series, pneumonia stood out as the source of the bacteremia, and -alcoholism/hepatic insufficiency as associated factor. In the first series, 48 isolates resulted susceptible to penicillin by agar diffusion, and 1 out of 36 patients with pneumonia had a change in the antibiotic therapy to penicillin. In the prospective series, we found 56 susceptible isolates, and the remaining four were classified as intermediate susceptibility according to the MIC value. Antibiotics were changed in 36 out of 50 patients with bacteremic pneumococcal pneumonia (p < 0.05). The infectious diseases specialist evaluation had a positive impact on the use of the microbiological information for therapeutics purposes.
La descripción creciente de Streptococcus pneu-moniae resistente a penicilina, ha llevado a la recomendación de emplear cefalosporinas de tercera generación para el tratamiento de las infecciones neumo-cócicas graves. Como consecuencia, los médicos clínicos no prescriben, usualmente, antimicrobianos de primera línea, a pesar de disponer de estudios de susceptibilidad in vitro. Con el propósito de evaluar el impacto de la asesoría del infectólogo para el uso adecuado de los estudios de susceptibilidad, se compararon dos series: un control histórico (1998-2002, n = 50) y un grupo prospectivo en que sí hubo asesoría infectológica (2003-2006, n = 60). En ambas series, la neumonía fue el foco principal de bacteriemia y alcoholismo/falla hepática los factores asociados más frecuentes. En el primer grupo, 48 aislados resultaron susceptibles a penicilina por prueba de difusión en agar y en uno de 36 pacientes con neumonía, se efectuó cambio en la terapia antimicrobiana a bencilpeni-cilina. En el grupo prospectivo, hubo 56 cepas susceptibles y las cuatro restantes fueron clasificadas como de susceptibilidad intermedia, de acuerdo con los valores de CIM. Se cambió de antimicrobiano en 36 de 50 pacientes con neumonía neumocóccica bacteriémica (p < 0,05). La evaluación hecha por el infectólogo tuvo un impacto positivo en el uso de información micro-biológica con fines terapéuticos.
Asunto(s)
Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Antibacterianos/uso terapéutico , Bacteriemia/tratamiento farmacológico , Neumonía Neumocócica/tratamiento farmacológico , Streptococcus pneumoniae/efectos de los fármacos , Bacteriemia/microbiología , Estudios de Casos y Controles , Pruebas de Sensibilidad Microbiana , Resistencia a las Penicilinas , Estudios ProspectivosRESUMEN
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.
Asunto(s)
Humanos , Aminoglicósidos/metabolismo , Antibacterianos/metabolismo , Farmacorresistencia Bacteriana/genética , Enterococcus/enzimología , Acetiltransferasas/genética , Aminoglicósidos/farmacología , Antibacterianos/farmacología , Chile , Enterococcus/efectos de los fármacos , Enterococcus/genética , Infecciones por Bacterias Grampositivas/microbiología , Hospitales , Datos de Secuencia Molecular , Fosfotransferasas (Aceptor de Grupo Alcohol)/genéticaRESUMEN
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.
Asunto(s)
Acinetobacter baumannii/enzimología , Antibacterianos/farmacología , Proteínas Bacterianas/biosíntesis , Resistencia betalactámica , beta-Lactamasas/biosíntesis , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/aislamiento & purificación , Chile , Farmacorresistencia Bacteriana , Humanos , Focalización Isoeléctrica , Pruebas de Sensibilidad MicrobianaRESUMEN
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.
Asunto(s)
Humanos , Acinetobacter baumannii/enzimología , Antibacterianos/farmacología , Resistencia betalactámica , Proteínas Bacterianas/biosíntesis , beta-Lactamasas/biosíntesis , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/aislamiento & purificación , Chile , Farmacorresistencia Bacteriana , Focalización Isoeléctrica , Pruebas de Sensibilidad MicrobianaRESUMEN
BACKGROUND: Klebsiella pneumoniae is an important pathogenic bacterium, frequently isolated from nosocomial samples, that exhibits wide antimicrobial resistance profiles, including third generation cephalosporins (3GC), aminoglycosides and quinolones. The resistance to 3GC is mainly due to the synthesis of extended spectrum beta lactamases (ESBL), encoded by conjugative plasmids. AIM: To investigate the potential transference of resistance to 3GC from nosocomial strains of K. pneumoniae to other clinical strains of various species of Enterobacteriaceae. MATERIAL AND METHODS: The mating experiments were carried out in liquid media and three nosocomial strains of K. pneumoniae were used as donors. These strains were ESBL-producers and resistant to, at least, one of the 3GC assayed. One strain of Citrobacter freundii, Salmonella typhimurium, Serratia marcescens and Escherichia coli, isolated from clinical specimens, were used as recipients. The presence of bla genes was investigated by PCR. RESULTS: The three nosocomial strains of K. pneumoniae were able to transfer the resistance to 3GC and the genes encoding the ESBL to the susceptible recipient strains of enterobacteria. The frequency of transference was as high as 3.2 x 10-2 transconjugants/recipient cell when the strain of Citrobacter freundii was used as recipient. All transconjugants exhibited high level of resistance to the 3GC assayed. CONCLUSIONS: Strains of K. pneumoniae isolated from Chilean hospitals are able to disseminate the ESBL genes to clinical strains of others species of Enterobacteriaaceae.
Asunto(s)
Antibacterianos/farmacología , Resistencia a las Cefalosporinas/genética , Cefalosporinas/farmacología , Klebsiella pneumoniae/enzimología , Transformación Bacteriana/genética , beta-Lactamasas/biosíntesis , Citrobacter freundii/efectos de los fármacos , Citrobacter freundii/enzimología , Escherichia coli/efectos de los fármacos , Escherichia coli/enzimología , Humanos , Klebsiella pneumoniae/efectos de los fármacos , Klebsiella pneumoniae/genética , Pruebas de Sensibilidad Microbiana , Reacción en Cadena de la Polimerasa , Salmonella typhimurium/efectos de los fármacos , Salmonella typhimurium/enzimología , Serratia marcescens/efectos de los fármacos , Serratia marcescens/enzimología , beta-Lactamasas/genéticaRESUMEN
Background: Klebsiella pneumoniae is an important pathogenic bacterium, frequently isolated from nosocomial samples, that exhibits wide antimicrobial resistance profiles, including third generation cephalosporins (3GC), aminoglycosides and quinolones. The resistance to 3GC is mainly due to the synthesis of extended spectrum beta lactamases (ESBL), encoded by conjugative plasmids. Aim: To investigate the potential transference of resistance to 3GC from nosocomial strains of K. pneumoniae to other clinical strains of various species of Enterobacteriaceae. Material and methods: The mating experiments were carried out in liquid media and three nosocomial strains of K. pneumoniae were used as donors. These strains were ESBL-producers and resistant to, at least, one of the 3GC assayed. One strain of Citrobacter freundii, Salmonella typhimurium, Serratia marcescens and Escherichia coli, isolated from clinical specimens, were used as recipients. The presence of bla genes was investigated by PCR. Results: The three nosocomial strains of K. pneumoniae were able to transfer the resistance to 3GC and the genes encoding the ESBL to the susceptible recipient strains of enterobacteria. The frequency of transference was as high as 3.2 x 10-2 transconjugants/recipient cell when the strain of Citrobacter freundii was used as recipient. All transconjugants exhibited high level of resistance to the 3GC assayed. Conclusions: Strains of K. pneumoniae isolated from Chilean hospitals are able to disseminate the ESBL genes to clinical strains of others species of Enterobacteriaaceae.