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D Domingo

Publications and source records attributed to D Domingo.

At least 19 recordsLinked to original sources
PubMed2006

[Susceptibility of 36 Helicobacter pylori clinical isolates to four first-line antibiotics and virulence factors].

Helicobacter pylori possess various virulence factors, including cagA and vacA genes, that are associated with more aggressive symptoms such as bleed-ing ulcer and gastric cancer. Although there are different treatment regimens, there is still a failure rate of up to 20% due to antibiotic resistance, among other causes. In our country resistance to metronidazole and clarithromycin is increasing, especially in children, although they are still susceptible to amoxicillin and tetracycline. In order to determine the susceptibility pattern to these antibiotics 36 H. pylori clinical isolates were studied. MIC was determined by agar diffusion and agar dilution, and vacA and cagA genes were detected by conventional PCR. All isolates were susceptible to amoxicillin and tetracycline. Resistance to metronidazole by diffusion or dilution tests was 35.7% and 36.1%, respectively, and to clarithromycin, 21.4% and 22.3%, respectively. There was one strain that showed intermediate resistance to clarithromycin (MIC 0.38 mg/l), using agar diffusion, and that was included among the resistant strains. Three discrepancies were observed between the diffusion and dilution methods. The vacA s1 allele was detected in 17.2% of the strains, and vacA s2 in 82.8%; 51.7% of the total were cagA+. In conclusion, all strains tested in our study were susceptible to amoxicillin and tetracycline, allowing them to be considered as first-line antibiotics, while clarithromycin and metronidazole maintain a slight increase in their resistance level. The cagA+ strains were detected in expected quantities, while the s1 allele of the vacA gene was detected in lower quantities.

Adult↗
PubMed2005

[Nontuberculous mycobacteria in patients with cystic fibrosis].

OBJECTIVE: Patients with cystic fibrosis are at great risk of infection by nontuberculous mycobacteria from the environment because of certain predisposing factors such as bronchiectasis, malnutrition, and diabetes. The aim of this study was to analyze the mycobacterial content of sputum smears and cultures from adult patients with cystic fibrosis attended at a specialized unit for adults from March 1997 through December 2001. PATIENTS AND METHODS: Sputum samples were collected prospectively according to a protocol applied at each visit, and during most exacerbations staining and culture for mycobacteria were ordered in addition to the usual cultures for bacteria and fungi. A tuberculin test was performed at the end of the study. RESULTS: Twenty-eight patients (16 men) with cystic fibrosis were enrolled. The mean (SD) age was 25.3 (6.7) years. A total of 251 samples were cultured (range in number of samples per patient, 1-31). The mean period of follow up was 40.3 (22.1) months. The sputum smear was positive in 29 cases (4 patients); the culture was positive in 7 patients. More than 3 samples were positive in only 4 patients. Mycobacterium abscessus was isolated in 3 cases, Mycobacterium avium complex in 2 and Mycobacterium simiae in 1 and other an unidentified rapid growth Mycobacterium species. The Mantoux test was positive in 5 patients. Two of the 4 patients in whose samples mycobacteria were isolated repeatedly required treatment. CONCLUSIONS: The prevalence of nontuberculous mycobacterial infection is high in patients with cystic fibrosis. Staining and culture for mycobacteria should be carried out regularly and whenever exacerbation of pulmonary symptoms cannot be attributed to bacteria usually found in such patients. Patients with recurrent isolations of mycobacteria should be monitored closely.

Adult↗
PubMed2005

[Resistance of Mycobacterium tuberculosis in a four-year period in a Madrid hospital].

Tuberculosis is considered a serious public health problem. Some factors, such as HIV infection and immigration, have had a major impact on the epidemiology of this illness in Spain. The problem has worsened in recent years due to the dissemination of multiresistant strains. Therefore, a periodic surveillance should be established with respect to the incidence and the resistances observed. In this study we collect M. tuberculosis isolates carried out in the years 2001, 2002, 2003 and 2004, and their susceptibility characteristics in patients from Area 2 in Madrid. To evaluate the isolates' susceptibilities, the MGIT 960 system was used. Of a total of 244 isolates, 15.2% were resistant to at least one antibiotic (different to streptomycin), and 29.9% of the isolates were obtained in samples from immigrant patients. In addition, the immigrant population affected showed a greater percentage of resistances (p <0.01) and a younger mean age (p <0.01) than the indigenous population.

Adult↗
PubMed2005

[In vitro activity of furazolidone and nitrofurantoin in Helicobacter pylori clinical isolates and study of mutation rate].

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.

Anti-Infective Agents↗
PubMed2003

[Detection of resistance to clarithromycin in clinical isolates of Helicobacter pylori from children and adults].

Several methods have been used to detect clarithromycin resistance. Agar dilution is now recommended by the NCCLS (susceptible to clarithromycin: MIC<=0.25 mg/l; intermediate resistance: MIC=0.5 mg/l; resistant: MIC>=1 mg/l), and the detection of mutations involved in resistance is used in many laboratories. We analyzed 36 clarithromycin-resistant strains isolated from children and 30 from adults. In vitro susceptibility to clarithromycin was determined by an agar dilution method. DNA from the isolates was extracted using the method published by Ge and Taylor. A2142G and A2143G mutations were identified by PCR-RFLP. A 1.4 Kpb of the 23S rRNA gene was amplified and digested using MboII or BsaI restriction enzymes to detect mutations. The prevalence of the A-G transition mutation at position 2143 was higher in the children (80.55%) than in the adult patients (46.66%) (p<0.05); however, the prevalence of the mutation at position 2142 was higher in adults than in children (36.66% vs. 5.55%; p<0.05). In children, a higher MIC (2-64 mg/l) was observed when the A-G mutation was detected at position 2143. However, in adult patients higher MICs were observed when the A-G mutation was detected at position 2142.

Adult↗
PubMed2003

[Susceptibility of Campylobacter jejuni clinical isolates from children to eight antibiotics].

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.

Amoxicillin-Potassium Clavulanate Combination↗
PubMed2002

[In vitro activity of clarithromycin and metronidazole against Helicobacter pylori in different incubation atmospheres].

The aim of this study was to determine the in vitro activity of clarithromycin and metronidazole using an agar dilution method to compare two different incubation atmospheres: a CO2 incubator and a jar with a microaerobic gas-generating system. Antibiotics were placed on plates in twofold dilutions ranging from 128 to 0.064 mg/l in Mueller-Hinton agar supplemented with 7% horse blood. The inoculum was prepared from 31 Helicobacter pylori isolates and was inoculated using a Steers replicator. Plates were incubated for 3 to 5 days and MICs were recorded as the lowest concentration of antibiotic inhibiting visible growth. Two different incubation atmospheres were used: a CO2 incubator set at 95% humidity and 10% CO2, and a jar with a gas-generating envelope that produces 7-10% O2 and 14% CO2 (BioMerieux). Clarithromycin resistance was found in 19% of strains both in the gas-generating system and the CO2 incubator. Metronidazole resistance was 23% in both atmospheres. MICs for clarithromycin in both atmospheres showed two dilutions of difference for 100% of the strains, and were slightly higher in the jar with a gas-generating envelope. However, MICs for metronidazole were higher when it was incubated in the CO2 incubator, and in 86.7% of strains the MICs showed < or = 2 dilutions of difference. No great discrepancies were found for either metronidazole or clarithromycin using the two methods.

Anti-Bacterial Agents↗
PubMed2001

A novel response of cancer cells to radiation involves autophagy and formation of acidic vesicles.

The mechanisms underlying neoplastic epithelial cell killing by ionizing radiation are largely unknown. We discovered a novel response to radiation manifested by autophagy and the development of acidic vesicular organelles (AVO). Acidification of AVO was mediated by the vacuolar H+-ATPase. Staining with the lysosomotropic agent acridine orange enabled us to quantify AVO accumulation and to demonstrate their time- and dose-dependent appearance. The appearance of AVO occurred in the presence of the pan-caspase inhibitor z-Val-Ala-Asp(Ome)-fluoromethyl ketone, but was inhibited by 3-methyladenine, an inhibitor of autophagy. The accretion of AVO in surviving progenies of irradiated cells, and the increased incidence of clonogenic death after inhibition of vacuolar H+-ATPase suggest that formation of acidic organelles represents a novel defense mechanism against radiation damage.

Adenine↗
PubMed2001

A 9 year study of clarithromycin and metronidazole resistance in Helicobacter pylori from Spanish children.

The evolution of clarithromycin, metronidazole and amoxycillin resistance in 246 Spanish Helicobacter pylori clinical isolates, obtained from paediatric patients during a 9 year period, was determined by an agar dilution technique. Clarithromycin resistance (MIC 1 mg/L) was 2.27% (IC95 0.05-12.02) in 1991-1993, 20.98% (IC95 12.72-31.46) in 1994-1996 and 28.33% (IC95 20.48-37.28) in 1997-1999 (P < 0.01). Metronidazole resistance (MIC 8 mg/L) was 7.14% (IC95 1.49-19.48) in 1991-1993, 20.25% (IC95 12.04-30.79) in 1994-1996 and 43.90% (IC95 32.95-55.30) in 1997-1999 (P < 0.01). Amoxycillin resistance was not found (all strains showed MICs < 2 mg/L).

Anti-Bacterial Agents↗
PubMed2000

Clarithromycin resistance stability in Helicobacter pylori: influence of the MIC and type of mutation in the 23S rRNA.

Thirty clarithromycin-resistant Helicobacter pylori strains (MIC range 8-64 mg/L) were subcultured in a drug-free medium and the MIC was determined every five passages to detect in vitro stability of resistance. Three out of the 30 (10%) lost their resistance after 10, 13 or 18 subcultures (MIC decrease from 8 to 0.008, from 16 to 0. 064 and from 32 to 0.016 mg/L). The effect of four macrolides at subinhibitory concentrations on the development of resistance was studied in H. pylori NCTC 11638 and TIGR 26695. A change in the MIC was observed only when NCTC11638 was exposed to 0.5 x MIC of erythromycin for 20 days.

Anti-Bacterial Agents↗
PubMed2000

Prevalence of CagA and VacA antibodies in children with Helicobacter pylori-associated peptic ulcer compared to prevalence in pediatric patients with active or nonactive chronic gastritis.

VacA and CagA serological responses were detected in pediatric patients: 44 and 56%, respectively, in peptic ulcer (PU) patients, 33.3 and 44.4% in active chronic gastritis (ACG) patients, and 23.2 and 39.2% in non-ACG patients. Higher seroprevalence to CagA+VacA and to CagA+VacA+35-kDa antigen was found among PU patients. However, a low level of sensitivity and specificity was found for indirect detection of PU patients.

Adolescent↗
PubMed2000

PCR using 3'-mismatched primers to detect A2142C mutation in 23S rRNA conferring resistance to clarithromycin in Helicobacter pylori clinical isolates.

Twenty-five clarithromycin-resistant Helicobacter pylori strains (selected by agar dilution) were studied to detect A2142G and A2143G mutations in the 23S rRNA gene by a PCR-restriction fragment length polymorphism method and an A2142C mutation by PCR using a 3'-mismatched specific primer. A 700-bp amplified fragment was obtained by the mismatched PCR only in strains without an A2142G or A2143G mutation, indicating that those strains had the A2142C mutation.

Anti-Bacterial Agents↗
PubMed2000

[In vitro activity of ascorbic acid].

The aim of this study was to determine the in vitro activity of ascorbic acid (vitamin C) against 43 Helicobacter pylori clinical isolates obtained from gastric biopsy taken by endoscopy. The MIC was determined by an agar dilution method. The ascorbic acid was included as two-fold dilutions in the agar to obtain a final concentration from 4000 mg/l to 62 mg/l. Brain-heart infusion agar supplemented with yeast extract and 10% fetal calf serum, 10(6) CFU/spot inoculum and microaerobic incubation for 2 to 5 days were used. MIC(50) 500 mg/l, MIC(90) 1000 mg/l and the range from 62 to 2000 mg/l. No differences in susceptible or resistant isolates were observed. Ascorbic acid showed good in vitro activity against the H. pylori clinical isolates tested in this study, which could explain some of the beneficial properties of vitamin C.

Ascorbic Acid↗
PubMed1999

Antibiotic resistance problems with Helicobacter pylori.

Helicobacter pylori is very susceptible in vitro to most antibiotics, but when they are used in the clinical setting, eradication of the bacteria from the gastric mucosa is not obtained. Dual or triple therapy including two of the following antibiotics: amoxicillin, tetracycline, metronidazole or clarithromycin, plus a proton pump inhibitor, bismuth salt or ranitidine bismuth citrate is the most frequently used. Various in vitro susceptibility methods have been used: disk diffusion, agar dilution and Epsilometer test (E-test). Metronidazole resistance among H. pylori strains is now found worldwide, and resistance rates vary according to the population studied. It is higher in developing than in developed countries and it could reach 80-90% in Africa. The prevalence on clarithromycin resistance is much lower, usually below 10%, although very high values are reported in Peru. Infection with metronidazole- or clarithromycin-resistant H. pylori strains is correlated with treatment failure when using regimens including these antibiotics.

Anti-Bacterial Agents↗
PubMed1999

In vitro activity of clinafloxacin against fluoroquinolone resistant Spanish clinical isolates.

The in vitro activity of clinafloxacin against 162 ciprofloxacin-resistant clinical isolates was determined. Isolates were selected when their MIC to ciprofloxacin was 2 mg/l (intermediate) or > 2 mg/l (resistant). The following strains were tested: 61 Escherichia coli, 12 Klebsiella pneumoniae, 7 Proteus mirabilis, 21 Serratia marcescens, 4 Enterobacter cloacae, 21 Pseudomonas aeruginosa, 21 Staphylococcus. aureus (resistant to methicillin) and 15 Enterococcus spp. Clinafloxacin, ciprofloxacin, ofloxacin and norfloxacin activities were evaluated by agar dilution using Müeller-Hinton agar according to NCCLS recommendations. Of the 162 isolates, 16 (9.8%) were intermediate and 146 (90.1%) resistant to ciprofloxacin. 95 of the 162 strains (58.6%) were susceptible, 27 (16.7%) intermediately susceptible, and 40 strains (24.7%) were resistant to clinafloxacin. The percentage susceptible to clinafloxacin was 65.6% for E. coli, 75% for K. pneumoniae, 71.4% for P. mirabilis, 28.6% for S. marcescens, 75% for E. cloacae, 33.3% for P. aeruginosa, 90.5% for S. aureus and 40% for Enterococcus spp. Clinafloxacin was active against 58.6% of the ciprofloxacin-resistant clinical isolates tested. It was particularly active against S. aureus strains resistant to both ciprofloxacin and methicillin.

Anti-Infective Agents↗