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T Alarcón

Publications and source records attributed to T Alarcón.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Celiac disease in adolescents and young adults. A challenge for gastroenterologists of children and adults].

BACKGROUND: Follow-up of celiac patients in Chile is often interrupted when adolescents are referred to adult gastroenterologists. AIM: To study the evolution of patients with celiac disease when they reach adolescence or young adulthood. PATIENTS AND METHODS: Current adherence to gluten-free diet and its relation to symptoms and circulating antiendomysial antibodies were evaluated in the 58 confirmed celiac patients older than 12 years of age controlled at 3 hospitals in Santiago. RESULTS: Mean age at the moment of this assessment was 17.8 +/- 5 years, 65.5% were women, 12.5% were at nutritional risk (-IDS) while 20% were overweight/obese. Although all patients declared themselves asymptomatic, a focused questionnaire revealed that 26% suffered some symptoms. Only 24.1% followed a strict gluten-free diet. Eight of 20 patients who ate gluten-containing diets had negative antiendomysial antibodies (EMA), three of whom turned positive within 6 to 9 months. In three of four (asymptomatic) cases that accepted a new jejunal biopsy, histology was abnormal. One patient who followed a strict diet had EMA (+) and normal histology. CONCLUSIONS: These results confirm that after childhood, symptoms abate significantly in celiac patients. The observed sensitivity and specificity of EMA makes necessary to maintain small intestinal biopsies as the gold standard for diagnosis and confirmation of the disease.

Adolescent↗
PubMed2001

[Prevalence of primary Helicobacter pylori resistance to eight antimicrobial agents in a hospital in Madrid].

The aim of this study was to determine the prevalence of primary Helicobacter pylori resistance, and to investigate the relationship with factors such as age and sex. During 1998, 106 H. pylori strains collected from dyspeptic patients who had had no previous H. pylori treatment were studied. The minimun inhibitory concentrations of metronidazole, amoxicillin, clarithromycin, tetracycline, azithromycin, clindamycin, cefotaxime and ciprofloxacin were determined by E-test.((R)). The overall prevalence of primary metronidazole resistance was 40.6%. Although it was more frequent in women than in men (44.4% vs. 37.7%), the difference was significant only in the women who were under 45 years of age. For the rest of the antibiotics, the primary resistance rates were the following: clarithromycin 9.5%, azithromycin 10.3%, clindamycin 13.1%, and ciprofloxacin 7.9%. No resistance to tetracycline and b-lactam antibiotics was found. Clarithromycin and amoxicillin were the most active compounds of the macrolides and b-lactams studied, respectively.

Adult↗
PubMed2001

In vitro activity of CA(1-8)M(1-18), a synthetic cecropin A-melittin hybrid peptide, against multiresistant Acinetobacter baumannii strains.

The in vitro antibiotic activity of CA(1-8)M(1-18), a synthetic cecropin A-melittin hybrid peptide, was determined by broth microdilution on 20 clinical Acinetobacter baumannii isolates with different resistance profiles. The MIC(50), MIC(90) and ranges were 4 mg/l, 4 mg/l and 2-8 mg/l, respectively, and were independent of resistance pattern. Different assay parameters such as microplate plastic (polystyrene or polypropylene), addition of supplements (5-10% fetal calf serum or 5% horse blood), inoculum size (10(5), 10(6), 10(7) and 10(8) CFU/ml) or incubation period (24 or 48 h) were studied. MIC was independent of the first two parameters, although the MIC values increased both with inoculum size or incubation period. Killing curves were obtained both for a standard strain and a multiresistant isolate over a 45.7-2.8 mg/l (16-1 mM) peptide range, using an initial inoculum of 10(5)-10(6) CFU/ml and 10(9)-10(10) CFU/ml. A concentration of 45.7 mg/l was required for complete killing. Accordingly, CA(1-8)M(1-18) showed good in vitro activity against the A. baumannii strains tested irrespective of the resistance to classical antibiotics, and could be a future candidate for multiresistant A. baumannii infections, although further cytotoxicity and pharmacological studies will be needed.

Acinetobacter↗
PubMed2000

Energy transduction in periodically driven non-hermitian systems.

We show a new mechanism to extract energy from nonequilibrium fluctuations typical of periodically driven non-Hermitian systems. The transduction of energy between the driving force and the system is revealed by an anomalous behavior of the susceptibility, leading to a diminution of the dissipated power and consequently to an improvement of the transport properties. The general framework is illustrated by the analysis of some relevant cases.

Research Support, Non-U.S. Gov't↗
PubMed2000

Comparison of three methods for identification of Streptococcus milleri group isolates to species level.

A collection of 180 clinical isolates of Streptococcus milleri group were identified to species level using two phenotypic methods (a commercial system and the reference method based on differential phenotypic reactions) and a genotypic method (hybridisation of the 16S rRNA gene with species-specific probes) in order to evaluate the performance of the respective methods. A high level of agreement (80%) was observed between the results of the reference method and the genotypic method. The highest level of agreement was found for the species Streptococcus anginosus (83%), a high level of agreement (76%) also being achieved for Streptococcus constellatus and Streptococcus intermedius. The sensitivity of the commercial system compared to the genotypic method was 76% overall, but it was low (57.5%) for Streptococcus intermedius. Twenty-five strains belonged to the recently described CI strains.

Bacterial Typing Techniques↗
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

Celiac disease in a Chilean population carrying Amerindian traits.

BACKGROUND: Although clinical manifestations of celiac disease may change throughout life, clinical, histologic, immunologic, and genetic studies show that there are incomplete forms of this condition, making it difficult to define the disease at a given moment. Because there is no information published in the Latin American-Amerindian population, this study was conducted to assess relations between these parameters in Chileans with celiac disease and their first-degree relatives. METHODS: Sixty-two persons with confirmed celiac disease (mean age, 17.9 +/- 5.1 years; 78.3% females) and 126 relatives (mean age, 27.9 +/- 17.2 years; 65.1% females) were evaluated. Clinical manifestations, antiendomysial antibodies (EMAs), and human leukocyte antigen (HLA) haplotypes were studied in patients. Additionally, jejunal biopsy specimens were assessed (light microscopy) in EMA-positive (EMA+) relatives. RESULTS: Of the patients, 24.1% adhered to a strict gluten-free diet; 26% were oligosymptomatic, and none were malnourished; 45% were EMA+; 13.8% who ingested gluten were EMA-negative (EMA-); one patient consuming a strict gluten-free diet was EMA+. The DQA1*0501 allele was present in the highest frequency (48%, P < 0.0005), whereas combinations of DQ8 were predominant. Of the relatives, 4.8% were EMA+; they had a significantly higher frequency of diarrhea, weight loss, and anorexia (P < 0.03); and all had abnormal histology in biopsy specimens. CONCLUSIONS: After childhood, celiac disease is oligosymptomatic and is often unrecognized by patients. Disease in 13.8% of patients and in 4.8% relatives appeared as incomplete forms of celiac disease. Predominance of DQ8 HLA haplotypes reflects the genetic Spanish-Mapuche heritage of this population.

Adolescent↗
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

Differences in genotypes of Helicobacter pylori from different human populations.

DNA motifs at several informative loci in more than 500 strains of Helicobacter pylori from five continents were studied by PCR and sequencing to gain insights into the evolution of this gastric pathogen. Five types of deletion, insertion, and substitution motifs were found at the right end of the H. pylori cag pathogenicity island. Of the three most common motifs, type I predominated in Spaniards, native Peruvians, and Guatemalan Ladinos (mixed Amerindian-European ancestry) and also in native Africans and U.S. residents; type II predominated among Japanese and Chinese; and type III predominated in Indians from Calcutta. Sequences in the cagA gene and in vacAm1 type alleles of the vacuolating cytotoxin gene (vacA) of strains from native Peruvians were also more like those from Spaniards than those from Asians. These indications of relatedness of Latin American and Spanish strains, despite the closer genetic relatedness of Amerindian and Asian people themselves, lead us to suggest that H. pylori may have been brought to the New World by European conquerors and colonists about 500 years ago. This thinking, in turn, suggests that H. pylori infection might have become widespread in people quite recently in human evolution.

Amino Acid Isomerases↗
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

[Evolution of antimicrobial susceptibility of Acinetobacter baumannii clinical isolates].

Acinetobacter baumannii is a microorganism frequently implicated in colonization and infection in hospitalized patients. An increase of resistance has been observed in recent years making these infections difficult to treat. The in vitro activity of 24 antibiotics, 15 betalactam agents and nine nonbetalactams, was studied in 156 A. baumannii clinical isolates. The strains were collected from different clinical samples obtained from inpatients (92%) and 8% were from outpatients. Evolution of susceptibility from January 1995 to December 1997 was studied. MIC of the following antibiotics was determined by the agar dilution method: ampicillin, ticarcillin, piperacillin, ampicillin-sulbactam, amoxicillin- clavulanic acid, ticarcillin-clavulanic acid, piperacillin-tazobactam, cefotaxime, ceftazidime, cefepime, imipenem, meropenem, clavulanic acid, sulbactam, tazobactam, amikacin, gentamicin, tobramycin, ofloxacin, doxycycline, fosfomycin, rifampin, azithromycin and colistin. Low antimicrobial susceptibility was observed in most A. baumannii strains. Colistin, imipenem, meropenem and ampicillin-sulbactam showed the greatest susceptibility (100, 88.4, 88.4 and 84.6%, respectively). A. baumannii strains from inpatients showed a lower antimicrobial susceptibility than strains from outpatients, who showed a high percentage of susceptibility to most antibiotics. Rifampin and azithromycin showed certain in vitro activity against the most susceptible A. baumannii strains. A progressive decrease in susceptibility to most antibiotics was observed during the period studied. Carbapenem-resistant A. baumannii emerged in 1996 and increased in 1997.

Acinetobacter↗
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

Five-year analysis of antimicrobial susceptibility of the Streptococcus milleri group.

Susceptibility to 17 antibiotics was studied in 180 strains of the Streptococcus milleri group (88 Streptococcus anginosus, 63 Streptococcus constellatus, and 29 Streptococcus intermedius) isolated over a 5-year period. Minimum inhibitory concentrations of penicillin were in the intermediate range for 5.6% of the strains. Resistance to erythromycin and clindamycin was found in 17.1% and 16.6% of the isolates, respectively. A steady increase in the susceptibility to ciprofloxacin was observed over the study period. Imipenem was the most active beta-lactam agent tested. Glycopeptide antibiotics showed excellent activity. Only slight differences between the three species were found in terms of antibiotic susceptibility. Intermediate resistance to penicillin is appearing among the Streptococcus milleri group in our area; consequently, care must be taken when choosing a macrolide for the management of infections caused by these microorganisms.

Anti-Bacterial Agents↗
PubMed1999

Genetic differences in HLA-DQA1* and DQB1* allelic distributions between celiac and control children in Santiago, Chile.

Celiac disease is a permanent gluten intolerance strongly associated with HLA class II antigens. The over presentation of particular HLA alleles and haplotypes has been described in several populations. Different lines of evidence obtained during the last years suggest that a particular HLA-DQ heterodimer, encoded by the DQA1*0501 and DQB1*0201 genes in cis or trans conformation, confers the primary disease susceptibility. We report the HLA class II allelic distribution and DQA1/ DQB1 genotypes in 62 Chilean celiac patients compared with 124 control subjects in Santiago, Chile. We found a pronounced increase of the "susceptible" alleles :DQA1*0501 (0.480 vs 0.169, Pc < 0.0005), DQB1*0302 (0.430 vs 0.242, Pc = 0.002) and DQB1*0201 (0.250 vs 0.125, Pc = 0.037) in celiac patients in comparison with control children. As for "protective" alleles, we detected a high frequency of DQA1*0101 (0.310 vs 0.160, Pc = 0.01), DQA1*0201 (0.105 vs 0.010, Pc < 0.0075) and DQB1*0301 (0.250 vs 0.100, Pc = 0.010) in controls. In relation to risk haplotypes, the main combination observed was the conformation DQ8 (DQB1*0302/DQA1*0301) over DQ2 (DQB1*0201/DQA1*0501). In conclusion, results show that celiac disease in Chilean patients is primarily associated with DQ8 conformation. This is concordant with the high frequency of DR4 alleles (in linkage disequilibrium with DQB1*0302) detected in Amerind groups in Chile, where DQB1*0302 is more frequent than DQB1*0201.

Adolescent↗
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↗
PubMed1999

Factors predictive of outcome on admission to an acute geriatric ward.

AIM: To investigate which factors predict outcome of elderly patients on discharge and at 6 months. METHODS: A prospective study in an acute geriatric ward. Within 48 h of admission, patients were assessed for social factors, geriatric problems, admission diagnoses, medication, function and mental ability. Outcome measures were mortality, length of stay, institutionalization, readmissions and attendance at accident and emergency within 6 months. RESULTS: 353 patients were studied, with a mean age of 81.8 years. Logistic regression analyses showed that variables predicting hospital mortality were Barthel index on admission, pre-morbid disability and polypharmacy. The only variable independently predictive of prolonged stay in hospital was a Barthel score of <45 on admission. Functional disability on admission was predictive of institutionalization on discharge. Variables predicting mortality within 6 months of discharge were Barthel index on admission <65, presence of pressure sores, malnutrition and polypharmacy. Variables independently predictive of institutionalization were mental state and a low pension. Those who took more than five drugs on admission were more likely to attend accident and emergency and be readmitted. CONCLUSION: Limited activities of daily living and geriatric problems on admission are the strongest predictive factors of outcome, independent of diagnoses.

Aged↗