[In vitro activity of furazolidone and nitrofurantoin in Helicobacter pylori clinical isolates and study of mutation rate]. / Actividad in vitro de la furazolidona y la nitrofurantoína en aislamientos clínicos de Helicobacter pylori y estudio de la tasa de mutación.

Clarithromycin, amoxicillin, tetracycline and metronidazole are the most frequently used antimicrobials for Helicobacter pylori infection treatment. While tetracycline and amoxicillin resistance are rare, clarithromycin and metronidazole resistance vary in different populations and are considered factors for treatment failure. The aim of this study was to determine the in vitro activity of furazolidone and nitrofurantoin in 164 H. pylori clinical isolates by agar dilution and to determine the spontaneous mutation rate. Metronidazole and clarithromycin resistance were 23.77% (CI95%: 18.96-29.14) and 16.78% (CI95%: 12.64-21.62), respectively; moreover, 1.4% (CI95%: 0.38-3.54) were intermediate to clarithromycin. All the isolates were susceptible to amoxicillin and tetracycline. Furazolidone and nitrofurantoin resistance rates were 1.82% (CI95%: 0.37-5.25) and 0.6% (CI95%: 0-3.35), respectively. The three furazolidone-resistant strains were nitrofurantoine-susceptible (MIC 4 mg/l for furazolidone and 2 mg/l for nitrofurantoin) and the nitrofurantoin-resistant strains were furazolidone-susceptible (MIC 4 mg/l for nitrofurantoin and 1 mg/l for furazolidone). These four strains were metronidazole-resistant (MIC 16 mg/l). Furazolidone or nitrofurantoin spontaneous mutants were not detected in the eight H. pylori strains tested. However, mutants with resistance to metronidazole were found with all the strains with a mutation rate of 7.4 x 10(-10) to 9.4 x 10(-10). Furazolidone and nitrofurantoin showed an excellent in vitro activity against the H. pylori clinical isolates included herein, supporting the usefulness of furazolidone as second-line antimicrobial after treatment failure or as first-line therapy in populations with low economical resources.

[Susceptibility of Campylobacter jejuni clinical isolates from children to eight antibiotics]. / Sensibilidad de Campylobacter jejuni a ocho antibióticos en cepas aisladas de muestras clínicas de niños.

This study aimed to identify the activity of eight antibiotics (ofloxacin, moxifloxacin, azithromycin, erythromycin, clindamycin, ampicillin, amoxicillin-clavulanic acid and tetracycline) against 80 strains of Campylobacter jejuni isolated from children. Minimal inhibitory concentrations (MIC) were determined by an agar dilution method. Resistance to azithromycin and erythromycin was considered when MIC > or =8 mg/l, to clindamycin when MIC > or =1 mg/l, to amoxicillin-clavulanic acid and ampicillin when MIC > or =32 mg/l, to ofloxacin and moxifloxacin when MIC > or =4 mg/l, and to tetracycline when MIC > or =16 mg/l. All strains tested were susceptible to amoxicillin-clavulanic acid. The lowest frequency of resistance was to azithromycin (2%), erythromycin (3.7%), clindamycin (4.4%) and ampicillin (4.9%), and the highest was to ofloxacin and tetracycline (61.7% for both), and moxifloxacin (37%). Considered the antibiotics of choice for the treatment of infections caused by this microorganism, macrolides showed excellent activity with MIC(90)=0.5 mg/l for azithromycin and MIC(90)=0.5 mg/l for erythromycin.

Sensibilidad de Campylobacter jejunia ocho antibióticos en cepas aisladasde muestras clínicas de niños / Susceptibility of Campylobacter jejuni clinical isolates from children to eight antibiotics

El objetivo del presente estudio fue conocer la sensibilidad de Campylobacter jejuni a ocho antimicrobianos. Se estudió la sensibilidad de 80 cepas aisladas de heces diarreicas de niños a los siguientes antibióticos: ofloxacino, moxifloxacino, azitromicina, eritromicina, clindamicina,ampicilina, amoxicilina-ácido clavulánico y tetraciclina. Las concentraciones mínimas inhibitorias (CMI) se determinaron mediante un método de dilución en agar, considerando resistencia a azitromicina y eritromicina cuando la CMI 8 mg/l, a clindamicina si la CMI 1 mg/l, a amoxicilina-ácido clavulánico y ampicilina si la CMI 32 mg/l, a ofloxacino y moxifloxacino si la CMI 4 mg/l y a tetraciclina si la CMI 16 mg/l.Todas las cepas fueron sensibles a amoxicilina-ácido clavulánico. Las tasas de resistencia más bajas las presentaron azitromicina, eritromicina, clindamicina y ampicilina, siendo del 2 por ciento, 3,7 por ciento, 4,4 por ciento y 4,9 por ciento respectivamente, y las más altas ofloxacino, tetraciclina y moxifloxacino, con resistencias del 61,7 por ciento para los dos primeros y del 37 por ciento para el tercero. Los macrólidos probados, grupo de antibióticos de elección en el tratamiento de las infecciones producidas por este microorganismo, presentaron una excelente actividad, con una CMI90 de 0,5 mg/l para la azitromicina y 2 mg/l para la eritromicina (AU)