Resistencia a nitrofuranos en Salmonella enterica aisladas de carne para consumo humano / Nitrofuran resistance in Salmonella enterica isolated from meat for human consumption

RESUMEN En el presente estudio, se analizaron los mecanismos de resistencia a nitrofuranos en 18 muestras cár nicas con Salmonella enterica (15 de pollo, 2 de ternera y 1 de cerdo) de mercados de Lima (Perú). Determinaron los serotipos de los aislamientos y la sensibilidad a furazolidona y nitrofurantoina (con y sin el inhibidor de bombas de expulsión Phenyl-Arginine-β-Naphthylamide [PAβN]), las mutaciones en los genes snrA y cnr por PCR y la transferabilidad de la resistencia por conjugación. Se identificaron 15 muestras con S. infantis (13 muestras de pollo), 2 con S. enteritidis y 1 con S. anatum. Todos los aisla mientos, excepto S. anatum, fueron resistentes a ambos nitrofuranos (concentración mínima inhibidora [CMI] a furazolidona: 32-64 µg/mL, CMI a nitrofurantoina: 128-256 µg/mL), sin diferencias al adicio narse PAβN. Todos los aislamientos resistentes a nitrofuranos presentaron sustituciones en snrA y cnr (S. infantis: snrA STOP-151; cnr STOP-137; S. enteritidis: snrA STOP-180; cnr STOP-179). No se detectaron mecanismos transferibles de resistencia a nitrofuranos.

ABSTRACT The mechanisms of resistance to nitrofurans from 18 meat samples with Salmonella enterica (chicken: 15; beef: 2; pork: 1) collected in Lima (Peru) were analyzed. The isolates were serotyped and the susceptibility levels to furazolidone and nitrofurantoin [with and without the efflux pump inhibitor Phenyl-Arginine- β-naphthylamide (PAβN)], the presence of mutations in the snrA and cnr genes and the transferability of resistance by conjugation were established. Fifteen samples with S. infantis (13 from chicken samples), 2 with S. enteritidis and 1 with S. anatum were identified. All isolates except the S. anatum were resistant to both nitrofurans showing MICs (minimum inhibitory concentration) of furazolidone and nitrofurantoin of 32-64 μg/mL and 128-256 μg/mL, respectively. The addition of PAßN had no effect on the MIC levels. All nitrofuran-resistant isolates showed amino acid codon alterations at both snrA and cnr (S. infantis: snrA STOP-151; cnr STOP-137; S. enteritidis: snrA STOP-180; cnr STOP-179). No transferable mecha nisms of nitrofuran resistance were detected.

Genotoxicidad de la furazolidona y la forma libre de su metabolito 3-amino-2-oxazolidona, mediante la prueba de micronúcleos en linfocitos humanos / Genotoxicity of furazolidone and the free form of the metabolite: 3-amino-2-oxazolidone, based on human lymphocytes micronucleus test

The aim of this trial was to assess the genotoxic effects of the main metabolite of furazolidone (3-amino-2-oxazolidone-AOZ), which is usually protein-bound (PB-AOZ). Because PB-AOZ is not available as a tool for biomedical research, the synthetic free form of AOZ (F-AOZ) was used to challenge human lymphocytes in the genotoxic quantification test of induced micronuclei on human lymphocytes. The level of exposure of lymphocytes to F-AOZ was calculated by determining the residual quantity of the Bg-AOZ (from liver and muscle) by HPLC, derived from broilers fed furazolidone included at 0.11% and 0.22% in feed, and allowing a seven day withdrawal time. Then F-AOZ and furazolidone as positive genotoxic group were added at various concentrations higher than the residual level indication to the in vitro preparations diluted both in dimethyl sulfoxide (DMSO) as follows: for furazolidone (FZD) groups of 10 μM (225 mg/g), 1.0 μM (225 mg/g), 0.1 μM (22.5 mg/g), and 0.001 μM (0.225 mg/g), as well as a negative control group and positive control with DMSO 10-3 M (0.130 mg/g) and arsenic 10-3 M (0.747 mg/g), respectively; for F-AOZ 0.01 μM (1.020 mg/g); 0.102 μM; 0.0005 μM (0.051 mg/g); and 0.0001 μM (0.001 mg/g) were tested, having the same controls groups as for FZD. Results show that furazolidone from 10.0 μM through 0.1 μM possesses a well defined genotoxic effect. Association frequency, relative risk and ANOVA test showed a statistically significant effect vs the negative control group (P = 0.001; P = 0.03 and P = 0.04, respectively). For F-AOZ the same statistical tests showed that only 0.01 μM was capable of inducing a genotoxic effect. These results suggest that furazolidone as parent compound is potentially capable of inducing genotoxicity in consumers. In contrast, only the highest concentration of F-AOZ was shown to induce a similar effect. Yet this concentration is well above the expected residual concentration after a 7-day withdrawal period. These results do not support the use of furazolidone in humans as it is now accepted and reveals that F-AOZ is a considerably lower hazard to public health than the parent compound. Yet, lack of evidence of the effect of bound-AOZ in a similar setting precludes further comparisons, but these results suggest that it seems unlikely that PB-AOZ is a real risk to public health. Further studies are warranted.

El objetivo de este estudio fue evaluar los efectos genotóxicos del metabolito principal de la furazolidona 3-amino-2-oxazolidona (AOZ) que usualmente se encuentra unido a la proteína (AOZ-UP). Debido a que no se dispone para investigación biomédica de AOZ-UP, se utilizó la forma libre de AOZ (AOZ-L) como desafío genotóxico por medio de la técnica de cuantificación de micronúcleos inducidos en linfocitos humanos. El nivel de exposición de linfocitos a AOZ-libre fue establecido con base en la determinación por cromatografía líquida de alta resolución (CLAR) de los residuos de AOZ-UP encontrados en músculo e hígado de pollos, producidos en forma comercial, expuestos a furazolidona (FZD) por medio del alimento a dosis de 0.11% y 0.22%, permitiendo un tiempo de retiro de 7 días. Se conformaron dos grupos furazolidona (FZD) con las siguientes concentraciones de 10 μM (225 mg/g), 1 μM (225 mg/g), 0.1 μM (22.5 mg/g), y 0.001 μM (0.225 mg/g), así como el grupo testigo negativo sulfoxido de dimetilo (DMSO) 10-3 μM (0.130 mg/g) y el testigo positivo arsénico 10-3 μM (0.747 mg/g). Para AOZ-libre las concentraciones fueron 0.01 μM (1.020 mg/g); 0.001 μM (0.102 mg/g); 0.0005 μM (0.051 mg/g); y 0.0001 μM (0.001 mg/g) con los mismos grupos testigo. Los resultados muestran que la furazolidona a concentraciones de 1.0 μM y 0.1 μM posee un efecto genotóxico bien definido. El grado de asociación se calculó por medio del riesgo relativo y prueba de ANDEVA, que mostró el efecto estadísticamente significativo al compararlo con el grupo testigo negativo (P = 0.001; P = 0.03 y P = 0.04, respectivamente). Para AOZ-L las mismas pruebas estadísticas mostraron que sólo la concentración 0.01 μM era capaz de inducir un efecto genotóxico. Estos resultados sugieren que la furazolidona como sal pura es potencialmente capaz de inducir efectos genotóxicos en humanos, en los que no se apoya su uso. En contraste, sólo la concentración más alta de AOZ-L mostró un efecto similar, pero dicha concentración es mayor que la encontrada como residual a los siete días de retiro y puede considerársele como un peligro mucho menor para la salud pública que el compuesto progenitor. Dada la falta de evidencia científica del efecto genotóxico del AOZ-UP no se pueden realizar comparaciones adicionales con lo obtenido aquí para AOZ-L, pero parecería poco probable calificar a los residuos de AOZ-UP como peligros reales para la salud pública, por lo que se requieren pruebas adicionales.

Furazolidona, tetraciclina e omeprazol: uma alternativa de baixo custo para erradicação de Helicobacter pylori em crianças / Furazolidone, tetracycline and omeprazole: a low-cost alternative for Helicobacter pylori eradication in children

OBJETIVOS: Avaliar furazolidona, tetraciclina e omeprazol como tratamento de primeira linha para Helicobacter pylori em crianças com sintomas digestivos. MÉTODOS: Ensaio clínico aberto, prospectivo e consecutivo. O estudo incluiu pacientes acima de 8 anos com dispepsia funcional, dor abdominal funcional, anormalidades histológicas graves (metaplasia intestinal, atrofia gástrica ou linfoma do tecido linfóide associado às mucosas) ou úlcera péptica. A presença de H. pylori foi definida com base em exame histológico e teste da urease. O regime medicamentoso consistiu de um tratamento de 7 dias com omeprazol, tetraciclina (ou doxiciclina) e furazolidona duas vezes por dia. A erradicação foi avaliada através de endoscopia digestiva alta 2 meses após o tratamento (exame histológico e teste da urease). Avaliações clínicas posteriores foram realizadas 7 dias e 2 meses após o tratamento. RESULTADOS: Foram incluídos 36 pacientes (21 meninas/15 meninos). A idade variou de 8 a 19 anos (média de 12,94+2,89 anos). Na análise por intenção de tratar (n = 36), a taxa de erradicação foi de 83,3 por cento (IC95 por cento 77,1-89,5), ao passo que na análise por protocolo (n = 29), foi de 89,7 por cento (IC95 por cento 84,6-94,7). A adesão foi melhor quando se utilizou doxiciclina, mas as taxas de sucesso foram semelhantes para as duas tetraciclinas. Não houve nenhuma variável associada à falha no tratamento. Foram relatados efeitos colaterais em 17 pacientes (47,2 por cento), principalmente dor abdominal (11/30,5 por cento), náusea (sete/19,4 por cento) e vômitos (cinco/13,9 por cento). CONCLUSÃO: A terapia tripla com furazolidona e tetraciclina é uma alternativa de baixo custo para o tratamento da infecção pelo H. pylori.

OBJECTIVE: To evaluate furazolidone, tetracycline and omeprazole as first line therapy for Helicobacter pylori in children with digestive symptoms. METHODS: Prospective and consecutive open trial. The study included patients older than 8 years old with functional dyspepsia, functional abdominal pain, severe histological abnormalities (intestinal metaplasia, gastric atrophy or mucosa-associated lymphoid tissue lymphoma) or peptic ulcer. H. pylori status was defined based both upon histology and rapid urease test. Drug regimen was a 7-day course of omeprazol, tetracycline (or doxycycline) and furazolidone twice daily. Eradication was assessed by upper endoscopy 2 months after treatment (histology and rapid urease test). Further clinical evaluation was done 7 days and 2 months after treatment. RESULTS: Thirty-six patients (21 female/15 male) were included. Age ranged from 8 to 19 years (mean 12.94+2.89 years). On intention-to-treat analysis (n = 36), eradication rate was 83.3 percent (95 percentCI 77.1-89.5) whereas in per-protocol analysis (n = 29), it was 89.7 percent (95 percentCI 84.6-94.7). Compliance was better when doxycycline was used, but the success rates were similar for the two tetracyclines. There was no variable associated with treatment failure. Side effects were reported in 17 patients (47.2 percent), mainly abdominal pain (11/30.5 percent), nausea (seven/19.4 percent) and vomiting (five/13.9 percent). CONCLUSION: Triple therapy with furazolidone and tetracycline is a low-cost alternative regimen to treat H. pylori infection.

Estudio de casos de urticaria anular aguda en pacientes hospitalizados en el servicio de Dermatología del Instituto de Salud del Niño durante el período 2003 al 2004 / Acute annular urticaria case study in patients hospitalized in the service of Dermatology of the Institute of Health of the Child during the period 2003 to 2004

La urticaria aguda en niños es una entidad frecuente, sin embargo su incidencia no está bien establecida. Una variante es la urticaria anular aguda o gigante que ha sido caracterizada en varios trabajos. Objetivo: Caracterizar la urticaria anular aguda en el Instituto Nacional de Salud del Niño. Material y métodos: Estudio observacional no concurrente de serie de casos. Se revisaron historias clínicas de pacientes hospitalizados del servicio de Dermatología del Instituto Nacional de Salud del Niño, Lima-Perú, con criterios de inclusión y exclusión. Resultados:Se hallaron 27 niños con diagnóstico de urticaria anular aguda,las lesiones más frecuentes fueron las placas violáceas y manchas residuales. El área más afectada fue el tórax y dentro de los factores desencadenantes más importantes se encontró el uso de furazolidona en el 59% de los casos. Conclusiones: La urticaria anular aguda o gigante es una reacción de hipersensibilidad con características propias asociada en un alto porcentaje al uso de furazolidona (AU)

Acute urticaria in children is a frequent disorder; however its incidence has not been established. Annular acute urticaria or giant urticaria is a variant which has been reported in several surveys. Objetive: Characterize acute annular urticaria at Instituto Nacional de Salud del Niño, Lima-Peru. Methods: Observational non-concurrent series of cases. We reviewed the medical records of hospitalized patients at Dermatology Service, Instituto Nacional de Salud del Niño, with inclusion and exclusion criteria. Results: We found 27 children with diagnosis of acute annular urticaria; the most frequent lesions were lilaceous plaques and residual patches.The most frequently affected area was chest and the most important triggering factor was the use of furazolidone. Conclusions: Acute annular urticaria is a hypersensitivity reaction with special characteristics, which is associated in a high percentage to use of furazolidone (AU)