Biomedical subjects

L Aguilar

Publications and source records attributed to L Aguilar.

At least 73 records · Page 4Linked to original sources

PubMed2000

Streptococcus pyogenes resistance to erythromycin in relation to macrolide consumption in Spain (1986-1997).

The relationship between Streptococcus pyogenes resistance to erythromycin and macrolide consumption in Spain was studied. Erythromycin resistance was highly correlated with the consumption of total macrolides (r = 0.88, P<0.01). When macrolides were grouped into posological subgroups according to their pharmacokinetic and pharmacodynamic properties and analysed separately, erythromycin resistance appeared to be related mainly to those macrolides taken twice daily (bd) (r = 0.86, P<0.01) and those taken once daily (od) (r = 0.87, P<0.01), but not to those taken four (qds) or three times a day (tds) (r = -0.04, P: = 0.90). A progressive increase in the erythromycin resistance curve was seen after the consecutive introduction of both bd and od macrolides, which contributed to the increase in the total macrolide consumption, replacing tds macrolide prescription. Although this ecological analysis cannot establish an unequivocal causal relationship between antibiotic consumption and S. pyogenes resistance, the data are consistent with the hypothesis that widespread use of macrolides, mainly of bd and od macrolides, resulted in an increased prevalence of S. pyogenes resistant to erythromycin in Spain.

Anti-Bacterial Agents↗

PubMed2000

In vitro activities of gemifloxacin versus five quinolones and two macrolides against 271 Spanish isolates of Legionella pneumophila: influence of charcoal on susceptibility test results.

The MICs at which 90% of isolates are inhibited for gemifloxacin, trovafloxacin, and grepafloxacin were low (</=0.01 microg/ml) for 271 Legionella isolates when they were determined by the broth microdilution method but increased (>/=6 dilutions) when they were determined by the agar dilution method. This was due to the charcoal in the agar dilution medium, as shown by the progressive decrease in the MICs when the charcoal concentrations decreased. As free drug is the active fraction, charcoal binding should be considered.

4-Quinolones↗

PubMed2000

In vitro susceptibilities of 400 Spanish isolates of Neisseria gonorrhoeae to gemifloxacin and 11 other antimicrobial agents.

The in vitro activity of gemifloxacin versus those of 11 other antimicrobial agents against 400 strains of Neisseria gonorrhoeae was determined by microdilution with supplemented GC agar. A total of 37.5% of the strains were beta-lactamase positive. A total of 70 and 6.4% of the beta-lactamase-negative strains exhibited intermediate and high-level penicillin resistance, respectively. Ceftriaxone and gemifloxacin were the most active drugs (MICs at which 90% of isolates are inhibited, 0.01 versus 0.007 microg/ml, respectively), with 100% of strains inhibited by 0.12 microg/ml.

Anti-Bacterial Agents↗

PubMed2000

Short-term bactericidal activity of amoxicillin and cefotaxime against penicillin-susceptible and -resistant pneumococcal strains: an in vitro pharmacodynamic simulation.

The 8-hour in vitro activity of serum-simulated concentrations of amoxicillin (obtained after 875 mg oral dose) and cefotaxime (obtained after a 1 g i.v. dose), against 20 strains of the 5 Streptococcus pneumoniae serotypes most prevalent in Spain, was explored. Despite a greater initial inocula decrease observed with cefotaxime against the resistant strains at the first sampling time, a decrease > or =99.9% was obtained with both beta-lactams from 6h onwards against the penicillin-susceptible strains; the same was observed for the penicillin-resistant strains with amoxicillin but not with cefotaxime.

Administration, Oral↗

PubMed1999

Phospholipid membranes form specific nonbilayer molecular arrangements that are antigenic.

Hexagonal phase (H(II))-preferring lipids such as phosphatidate, cardiolipin, and phosphatidylserine form nonbilayer molecular arrangements in lipid bilayers. While their presence in biological membranes has not been established, in vitro studies suggest that alterations in membrane properties modify their function. In this study, antiphospholipid monoclonal antibodies were developed against nonbilayer structures. One of the monoclonal antibodies identifies nonplanar surfaces in liposomes and in membranes of cultured cells. These results are the first evidence that natural membranes maintain a fragile balance between bilayer and nonbilayer lipid arrangements. Therefore, these antibodies can be used to evaluate the role of H(II)-preferring lipids in the modulation of membrane activities. Our studies demonstrated that nonplanar surfaces are highly immunogenic. Although these structures are normally transient, their formation can be stabilized by temperature variations, drugs, antibiotics, apolar peptides, and divalent cations. Our studies demonstrated that abnormal exposure of nonbilayer arrangements may induce autoimmune responses as found in the antiphospholipid syndrome.

Animals↗

PubMed1999

Low prevalence of diphtheria immunity in the Spanish population: results of a cross-sectional study.

A seroepidemiological study was conducted on a representative sample (n = 3944) of the Spanish population to assess the immune status to diphtheria. A total of 1907 men and 2037 women in the 5-59 years age range were stratified by sex and age (5-12, 13-19, 20-29, 30-39, 40-49, 50-59 years). Concentrations of toxin antibodies were measured using a commercial ELISA kit. Samples with titres > or = 0.1 IU/ml were considered to show full protection. Only 26% (95% CI: 25-28%) of the overall population studied was fully protected. The highest number of subjects with uncertain or no protection was found in the 20-39 age group (> 85%). The prevalence of fully protected subjects progressively declined from 51% for the 5-12 year age group, to 14% for the 30-39 year age group, whereas it increased to 20% and 35% for the 40-49 and the 50-59 year age groups, respectively (p < 0.0001). These results stress the need to intensify vaccination programs in adolescents and adults with periodic booster doses of diphtheria toxoid.

Adolescent↗

PubMed1999

Is sexual transmission an important pattern for herpes simplex type 2 virus seroconversion in the Spanish general population?

Herpes simplex type 2 (HSV-2) seroprevalence within a community is determined by sexual and perinatal transmission from mother to baby, the two main sources of virus shedding. A seroepidemiological study of HSV-2 was undertaken on a representative sample (n = 3974) of the Spanish population to assess indirectly the relative relevance of these two transmission routes. The sample comprised 1922 men and 2052 women in the age range 5-59 years, stratified by sex and age (5-12, 13-19, 20-29, 30-39, 40-49, and 50-59 years). Sera were screened for HSV-2 specific Ig G antibodies by an enzyme-linked immunoabsorbent assay based on recombinant glycoprotein G2 (gG2). The overall prevalence of antibodies to HSV-2 was 3.6% (95% CI: 3. 1-4.2%). Prevalence by gender did not differ: males (3.6%; 95% CI: 2. 8-4.6%) and females (3.6%; 95% CI: 2.8-4.5%). There were no significant differences between age groups with respect to seropositivity rates. Detection of HSV-2 antibodies was not associated with increasing age, as is expected for a sexually transmitted disease. The fact that seroprevalence rates among the different age groups did not differ suggests that the virus is not circulating in the general population and may be restricted to risk groups only. Similar positivity rates found in the group of females of childbearing age and in the youngest population indicate that perinatal viral shedding is the main source of HSV-2 seroconversion in the Spanish population.

Adolescent↗

PubMed1999

Whole cell lysate enzyme immunoassays vs. recombinant glycoprotein G2-based immunoassays for HSV-2 seroprevalence studies.

Seroepidemiology studies of herpes simplex virus type 2 (HSV-2) infections have been difficult to carry out because antibodies to HSV type 1 (HSV-1) show an extensive cross-reactivity with HSV-2 antigens. Many kits available currently are not entirely type specific for serodiagnosis of HSV-2 infections and therefore do not allow reliable discrimination of past exposure to these closely related alphaherpes viruses. Attempts to develop type-specific antigens have focused on the envelope glycoproteins, particularly glycoprotein G (gG). A cross-sectional study was carried out to examine the seroprevalence of antibodies to HSV-2 among healthy university students, using different methods: a whole cell lysate enzyme-linked immunosorbent assay (ELISA), two different ELISAs, and a newly developed immunoblot assay, the last three based on recombinant gG2. HSV-2 prevalence was 24 times higher with the whole cell lysate ELISA (31%; 95% confidence interval [CI]: 27-35%) than the ELISAs and the immunoblot assay based on recombinant gG2 (1.3%; 95% CI: 0.1-2.5%), thus showing the inaccuracy of commercial tests based on whole-antigen preparations for epidemiological studies. Laboratories should be cautious and ensure that commercial tests for HSV typing are based on type-specific glycoproteins.

Adolescent↗

PubMed1999

Antimicrobial susceptibility of 1,422 Haemophilus influenzae isolates from respiratory tract infections in Spain. Results of a 1-year (1996-97) multicenter surveillance study. Spanish Surveillance Group for Respiratory Pathogens.

A Haemophilus influenzae multicenter antimicrobial susceptibility surveillance was carried out. An overall beta-lactamase production rate of 25.7% was found, with significant differences between hospitals ranging between 7.9 and 47.9%. Presumable intrinsic resistance was found in 4.6% of strains. No differences in susceptibility were observed between beta-lactamase positive and beta-lactamase negative strains for all antibiotics, except for penicillin, amoxicillin and cefaclor. A higher prevalence of resistance was found for clarithromycin vs azithromycin (22.6 vs 0.7%). Differences in all these factors make surveillance essential as a guideline for empiric treatment in community-acquired respiratory tract infections.

Drug Resistance, Microbial↗

PubMed1999

Prevalence of hepatitis A in an institution for the mentally retarded in an intermediate endemicity area: influence of age length of institutionalization.

OBJECTIVE: This study aimed to examine the prevalence of antibodies against hepatitis A (anti-HAV) in a population of institutionalized mentally retarded persons compared with that of institutionalized non-mentally retarded persons in an area with moderate endemicity of HAV infection. METHODS: The study population was a group of mentally retarded persons aged between 10 and 30 years, institutionalized in one residence in Madrid, Spain. A group of non-mentally retarded subjects in the same age range was chosen as controls. Information about demography and duration of institutionalization was obtained by the investigator. Four drops of whole blood were obtained from each person by finger-stick, collected on filter paper, air-dried and stored at +4 degrees C until antibody determination. Eluates were tested by an ELISA method. RESULTS: A total of 314 institutionalized subjects were included: 157 mentally retarded (mean age and mean duration of institutionalization were 24.4+/-3 and 9.7+/-5 years respectively) and 157 non-mentally retarded (mean age and mean duration of institutionalization were 19.2+/-5 and 4.6+/-3 years respectively). The prevalence of anti-HAV antibody was 54% (95% confidence interval (CI) 50-58) in mentally retarded and 22% (95% CI 19-25) in non-mentally retarded [P<0.001; odds ratio (OR): 4.2 (95% CI 2.5-7)]. In both groups, these differences were not statistically significant for anti-HAV antibody prevalence between persons institutionalized for >5 years compared with those institutionalized for < or = 5 years. CONCLUSIONS: There results indicate that in an area of moderate endemicity the institutionalized mentally retarded are at increased risk of having acquired hepatitis A infection compared to the non-mentally retarded. In these institutionalized persons, regardless whether they are mentally retarded or not, prevalence is not influenced by age or length of stay in institutions.

Adolescent↗

PubMed1999

Antimicrobial treatment of an experimental otitis media caused by a beta-lactamase positive isolate of Haemophilus influenzae.

A gerbil model of otitis media induced by a beta-lactamase producing and non-serotypeable isolate of Haemophilus influenzae was used to assess the in-vivo efficacy of co-amoxiclav and cefuroxime at low (5 mg/kg) and high (20 mg/kg) doses. The MIC of the antibiotics tested against the pathogen was 1 mg/L (1/0.5 mg/L for co-amoxiclav). The organism was inoculated (+/-10(6) cfu) by transbullar challenge directly in the middle ear and antibiotic treatment was commenced 2 h post-inoculation and continued at 8 h intervals for three doses. Only high dose co-amoxiclav significantly reduced the number of culture-positive specimens as compared with untreated animals or with other treatment groups (91.7% as compared with 36.7% for high dose cefuroxime). The results obtained in any treatment group were related to middle ear antibiotic level/MIC. Antibiotic concentrations in the middle ear 90 min after administration were about 10% of serum levels at 15 min, probably related to a slight inflammatory response. Only after high dose co-amoxiclav did the concentration in the middle ear exceed the MIC by a factor of four. In otitis media with effusion, if indicated, antibiotics active in vitro should be administered in high doses and, to avoid side effects, probably in short courses.

Amoxicillin-Potassium Clavulanate Combination↗

PubMed1999

Antimicrobial resistance of 914 beta-hemolytic streptococci isolated from pharyngeal swabs in Spain: results of a 1-year (1996-1997) multicenter surveillance study. The Spanish Surveillance Group for Respiratory Pathogens.

A nationwide susceptibility surveillance study of beta-hemolytic streptococcal isolates from pharyngeal swabs obtained in 11 Spanish hospitals between May 1996 and April 1997 against 12 antibiotics was carried out. Of the isolates 86% (786 of 914 isolates) were group A and 8.4% (77 of 914 isolates) were group C. No resistance was found to beta-lactam antibiotics, but significant differences (P < 0.001) with respect to lack of susceptibility to macrolides were found between groups (27% for group A and 12% for group C) and between seasons (13.2% in summer and 31.7% in winter). Most of these isolates displayed the M phenotype (low-level resistance to erythromycin and susceptibility to clindamycin).

Drug Resistance, Microbial↗

PubMed1999

Antimicrobial resistance of 1,113 Streptococcus pneumoniae isolates from patients with respiratory tract infections in Spain: results of a 1-year (1996-1997) multicenter surveillance study. The Spanish Surveillance Group for Respiratory Pathogens.

A nationwide susceptibility surveillance of 1,113 Streptococcus pneumoniae isolates was carried out and found the following percentages of resistance: cefuroxime, 46%; penicillin, 37%; macrolides, 33%; aminopenicillins, 24%; cefotaxime, 13%; and ceftriaxone, 8%. A significant (P < 0.05) seasonality pattern for beta-lactam antibiotics was observed. Resistance to macrolides was higher (P < 0.05) in middle-ear samples. Higher percentages of resistance to cefuroxime and macrolides were observed among penicillin-intermediate and -resistant strains, whereas high frequencies of resistance to aminopenicillins and expanded-spectrum cephalosporins were observed only among penicillin-resistant strains.

Cefuroxime↗

PubMed1999

Is there an ecological relationship between rates of antibiotic resistance of species of the genus Streptococcus? The Spanish Surveillance Group for Respiratory Pathogens.

The relationship between resistance to antibiotics on the part of Streptococcus pneumoniae and Streptococcus pyogenes was studied by comparing different prevalences of resistance among hospitals obtained from a recent microbiological surveillance of community-acquired respiratory tract infections. A high correlation for erythromycin resistance was found between S. pneumoniae isolates from lower respiratory tract infections and S. pyogenes isolates collected from pharyngeal swabs.

Drug Resistance, Microbial↗

PubMed1999

Influence of comorbidity and severity on the clinical outcome of bacteremic pneumococcal pneumonia treated with beta-lactam monotherapy.

The influence of the severity of pneumonia and comorbidity factors, as predictors of clinical outcome, was assessed in patients with microbiologically documented pneumococcal bacteremic pneumonia treated with penicillin or third generation cephalosporin monotherapy in a 5-year retrospective study. Among 288 patients admitted to three Spanish hospitals with bacteremic pneumococcal pneumonia, 65 (23%) were included. Twenty-four were treated with penicillins and 41 with a third-generation cephalosporin. Twenty-seven patients (42%) had severe pneumonia and 41 (63%) had a comorbidity index >1. Twenty-one patients (32%) were infected with penicillin-resistant strains. Four cases (2 with penicillin-resistant strains; 3 treated with cephalosporins) were clinical failures. Four cases (3 with penicillin-resistant strains; 2 treated with cephalosporins) died, i.e. 6% mortality rate. The only factor that influenced empirical treatment election was HIV-positive condition. Clinical outcome was not influenced by treatment election, penicillin susceptibility of the infecting pneumococci, patient basal conditions or severity of pneumonia, but the latter was associated with mortality and length of hospitalization.

Adolescent↗

PubMed1999

Does the degree of penicillin susceptibility of Streptococcus pneumoniae affect the bactericidal activity of co-amoxiclav versus oral cephalosporins at physiological concentrations? An in vitro pharmacodynamic simulation.

An in vitro model simulating amoxicillin-clavulanic acid (co-amoxiclav) versus oral cephalosporin serum concentrations was used to explore activity over time against penicillin-susceptible and non-susceptible Streptococcus pneumoniae. Initial inoculum reduction > 4 log cfu/ml (>99.9%) was obtained with co-amoxiclav against both strains. Cefuroxime, cefpodoxime and cefaclor achieved a similar reduction against the susceptible strain, but no reduction against the non-susceptible strain.

Amoxicillin-Potassium Clavulanate Combination↗

PubMed1999

Prevalence and risk of cysticercosis and taeniasis in an urban population of soldiers and their relatives.

To determine markers of Taenia solium transmission and risk factors in an urban community, we studied 1,000 soldiers from a military camp in Mexico City and their relatives. Serum samples were used to detect antigens and antibodies and fecal specimens were examined for Taenia coproantigens and helminth eggs. Prevalences of 12.2% and 5.8% for cysticercosis were found among soldiers and their relatives, respectively. Taeniasis was found in 0.5% and none of the groups, respectively. Relatives of soldiers positive for cysticercosis and taeniasis markers ate more pork from street stores than restaurants or markets compared with relatives of soldiers without these indicators of infection. Also, 12.0% of the relatives of positive soldiers had a history of expelling tapeworm proglottids in the feces in contrast to 3.7% of the family members of the control group. Prevalence values and risk factors in this urban population are similar to those of previous studies performed in rural populations.

Adult↗

PubMed1999

DNA image cytometry. An alternative method in osteoblast proliferation assays.

OBJECTIVE: To assess whether DNA image cytometry can be used as an alternative method to tritiated thymidine uptake quantification in osteoblast proliferation assays. STUD DESIGN: Proliferation of normal human osteoblasts incubated with normal human serum at 0%, 2.5%, 5%, 10%, 20% and 40% was quantified by tritiated thymidine uptake quantification and DNA image cytometry. RESULTS: Tritiated thymidine uptake quantification showed that normal human serum stimulated the proliferation of normal human osteoblasts and that the degree of stimulation was directly related to the concentration of serum in the culture medium. Similar results were obtained when the DNA image cytometry assay was used. A highly significant linear relationship between the ranks of both methods was found (Spearman's r = 1.00, P = .0253). CONCLUSION: DNA image cytometry may be a valuable alternative when the use of radioactive material is not desired and/or subsequent morphologic or immunocytochemical characterization of cells under study is required.

Aged↗