PubMed Health⌕ Search

Biomedical subjects

V Fernández-Baca

Publications and source records attributed to V Fernández-Baca.

10 recordsLinked to original sources
PubMed2001

Molecular epidemiological typing of Enterobacter cloacae isolates from a neonatal intensive care unit: three-year prospective study.

Since 1992, there has been an increase in the incidence of Enterobacter sepsis in the neonatal intensive care unit (NICU) of the authors' hospital. From 1995 to 1997, a prospective molecular epidemiological survey of the colonizing and infecting strains isolated from neonates was conducted. Enterobacter cloacae was the most frequent cause of neonatal sepsis, accounting for 19.2% of all neonatal infections, reaching a peak incidence of 2.2/1000 during 1996. Fifty isolates from the NICU and four epidemiologically unrelated strains were characterized by pulse-field gel electrophoresis (PFGE), ribotyping, enterobacterial repetitive intergenic consensus (ERIC)-PCR and plasmid profiling. PFGE was the most discriminatory technique and identified 13 types (two of them classified into two and three subtypes) compared with ERIC-PCR, plasmid profiling and ribotyping that identified 11, 11 and seven types, respectively. A good correlation was found between all techniques. Five different clones caused 15 cases of sepsis. Clones A and B were prevalent in 1995 and 1996, but they were not isolated in 1997. An outbreak caused by clone G in 1997 was controlled by cohort nursing and hygienic measures, without changing the antibiotic policy. Strains were characterized by their antibiotic resistance pattern and divided into three groups. Group I correlated with PFGE types A, B1 and B2, which hyperproduced Bush type 1 chromosomal beta-lactamase and expressed extended-spectrum ?-lactamases (ESBLs). Group II only hyperproduced Bush type 1 chromosomal beta-lactamase and correlated with PFGE-types D1, D2, D3 and I. Finally, Group III, with inducible beta-lactamases, correlated with the rest of PFGE types. The sudden disappearance of E. cloacae after reinforcement of hygienic measures confirms the importance of patient-to-patient transmission.

Bacterial Typing Techniques↗
PubMed1995

In vitro activity of amphotericin B, flucytosine and fluconazole against yeasts causing bloodstream infections.

The in vitro activity of amphotericin B, flucytosine and fluconazole against 95 yeasts causing fungemia in a single institution over the last eight years was determined by a broth macromethod recommended by the National Committee for Clinical Laboratory Standards. All strains were inhibited by amphotericin B concentrations of < or = 1 microgram/ml. With flucytosine in most species the MIC50 was between 0.12 and 0.25 microgram/ml and the MIC90 was between 0.25 and 1 microgram/ml. One exception with flucytosine was Candida krusei, with an MIC50 and MIC90 of 16 micrograms/ml and 32 micrograms/ml, respectively. Overall, 12% of the isolates needed at least 8 micrograms/ml of fluconazole to be inhibited. Fluconazole was very active against Candida albicans, Candida tropicalis and Cryptococcus neoformans, with MIC50 ranging from 0.12 to 0.5 microgram/ml and MIC90 of 1 microgram/ml, and somewhat less active against Candida parapsilosis (MIC50 of 1 microgram/ml and MIC90 of 4 micrograms/ml). Fluconazole exhibited poor in vitro activity against Candida krusei (MIC50 and MIC90 of 64 micrograms/ml) and Torulopsis glabrata (MIC50 of 4 micrograms/ml and MIC90 of 16 micrograms/ml). High MICs of fluconazole were found for four strains of Candida albicans, one with an MIC of 4 micrograms/ml and three (5.7%) with MICs of > or = 16 micrograms/ml. Previous exposure to fluconazole could be demonstrated in two of these strains. Further work must be done in order to determine appropriate breakpoints of antifungal agents, to assess the clinical relevance of azole resistance in yeasts causing bloodstream infections and to identify risk factors for infections with azole-resistant yeasts.

Amphotericin B↗
PubMed1995

[Presence of virulence factors and pathovars in strains of Campylobacter jejuni isolated from patients with diarrhea and healthy children].

BACKGROUND: To study the prevalence of virulence factors (adhesion, invasion, cytotoxicity and hemolytic activity) and to establish the presence of pathovars (virulence phenotype) in C. jejuni strains isolated in pediatric patients with inflammatory and secretory diarrhea and asymptomatic carriers. METHODS: We analyzed 95 strains of 48 patients with inflammatory diarrhea (blood and mucus in feces), 30 patients with secretory diarrhea (watery) and 17 strains isolated in asymptomatic children (control group). The study of adherence capacity, invasion and cytotoxicity was made in the Hep-2 cell line, and the analysis of hemolytic activity in blood agar plates with a 5% sheep's blood. The pathovars were defined by the cellular adhesion (phenotypes A and a) and the cytotoxicity (phenotypes E and e). RESULTS: 29.1% of inflammatory strains presented adherence capacity, 66.6% were invasive, 64.5% cytotoxic and 52.1% hemolytic. In the secretory strains the values were 70, 20, 10 and 6.6% respectively; in the control group the 11.7% presented adherence capacity and 5.8% were invasive. We obtained difference statistically significative for the secretory strains in the adherence capacity, and in inflammatory strains in the adherence capacity, cytotoxicity and hemolysis. The phenotype Ae predominate in the secretory strains, and the phenotype ae in the strains belonging to the control group. No pathovar predominates in the inflammatory strains. CONCLUSIONS: The analysis of virulence markers permit us to establish the pathogenic behaviour of the C. jejuni strains isolated in patients with diarrhea. The study of the adherence capacity and cytotoxicity (pathovars) would be used as a virulence markers and to predict the inflammatory or secretory nature of the diarrhea caused by C. jejuni strains.

Bacterial Adhesion↗
PubMed1994

Treatment of deep mycoses with liposomal amphotericin B.

Amphotericin B is the mainstay of therapy of many deep mycoses, but its use is seriously hampered by dose-limiting nephrotoxicity. In this study a liposomal formulation of amphotericin B was administered to ten patients with proven deep mycoses: invasive aspergillosis (n = 4), deep candidiasis (n = 4) and zygomycosis (n = 2). The mean daily dosage of liposomal amphotericin B was 3.0 mg/kg (range 2.5 to 4 mg/kg), the mean total dosage of liposomal amphotericin B 2,781 mg (range 87 to 5,220 mg) and the mean duration of treatment 17 days (range 3 to 33 days). Treatment with liposomal amphotericin B was associated with little nephrotoxicity and an overall survival rate of 50%. The median increase of serum creatinine from baseline levels was 0.38 mg/dl (-1.2 to 2.6 mg/dl).

Adult↗
PubMed1994

Evolution of susceptibilities of Campylobacter spp. to quinolones and macrolides.

Erythromycin, new macrolides, and quinolones are alternatives for the treatment of Campylobacter infections. Concerns related to the emergence of resistance to both groups of drugs have been raised. We studied the evolution of antimicrobial susceptibilities of 275 clinical isolates of microorganisms of the genus Campylobacter isolated in our institution during a 5-year period (1988 to 1992). The microorganisms studied were C. jejuni (n = 230), C. coli (n = 42), and C. fetus (n = 3). The overall resistance rates (determined by the agar dilution method and the recommendations of the National Committee for Clinical Laboratory Standards) were as follows: erythromycin, 2.3%; clarithromycin, 2.3%; azithromycin, 1.9%; ciprofloxacin, 28.5%; norfloxacin, 31%; ofloxacin, 26.3%; and nalidixic acid, 36.8%. The evolution of resistance (percent resistance in 1988 versus percent resistance in 1992) was as follows: erythromycin, 2.6 versus 3.1; clarithromycin, 2.6 versus 3.1; azithromycin, 2.6 versus 3.1; ciprofloxacin, 0 versus 49.5; norfloxacin, 2.6 versus 55.5; ofloxacin, 0 versus 45.6; nalidixic acid, 2.6 versus 56.8. Our data show stable macrolide activity against Campylobacter spp. and the rapid development of quinolone resistance over the last 5 years.

4-Quinolones↗
PubMed1994

Aeromonas peritonitis.

Five new cases of peritonitis caused by Aeromonas species are reported, and 29 others described in the literature are reviewed. Males predominated (71%), and the mean age was 56.9 years. Acquisition was nosocomial in 20% of the cases. All patients except one (3%) had significant underlying diseases; 73% had chronic hepatic disease, 15% had chronic renal failure (treated with chronic ambulatory peritoneal dialysis [CAPD]), and 9% had an intestinal perforation. Symptoms were similar to those of peritonitis caused by other pathogens, with the exception of diarrhea, which occurred in 25% of cases. Blood cultures were positive in 74% of the cases. The species isolated were Aeromonas hydrophila (27), Aeromonas sobria (5), and Aeromonas caviae (2). The overall case-fatality rate was 57%. Three strains were resistant to cotrimoxazole. Aeromonas species should be taken into account as a cause of peritonitis in patients with cirrhosis or who are undergoing CAPD.

Adolescent↗
PubMedDate not supplied

[Evaluation of 2 fast methods for the detection of rotaviruses in fecal samples].

BACKGROUND: Rotavirus is one of the major causes of acute gastroenteritis in childhood. Several rapid methods for rotavirus detection are currently available, although their efficacy have a great variability. We performed a prospective study to evaluate two rapid tests for detection of rotavirus antigens in faeces. METHODS: Using electron microscopy as the reference method, we compared two techniques for diagnosis of rotavirus infection: a monoclonal ELISA (Rotaclone, Cambridge Bioscencer, Worcester) and a policlonal latex agglutination (Diarlex, Orion Diagnostics, Finland). We tested, in parallel, 192 stools samples received in our laboratory to investigate rotavirus. RESULTS: ELISA showed significantly better sensitivity than latex (100 vs 66.6%), while both methods had similar specificity (98.6%). CONCLUSIONS: Of the tested methods, ELISA was superior due to the high sensibility and specificity, good reproductibility and easy interpretation. It also permits the simultaneous performance of several tests.

Enzyme-Linked Immunosorbent Assay↗
PubMedDate not supplied

[Isolation of cytomegalovirus from peripheral blood by shell-vial culture. Technical considerations].

BACKGROUND: We performed an study of the possible benefits derived from the use of two vials, incubated for 24 and 72 h respectively, in the isolation of CMV from the leukocyte polymorphonuclear (LPMN) of peripheral blood (viremia) in immunosuppressed patients, using the shell-vial culture technique. MATERIAL AND METHODS: The blood samples with EDTA were fractionated by sedimentation with saline dextran. The LPMN-rich upper layer was used for the isolation of CMV in the shell-vial cell culture (MRC-5 cell line) and to prepare the antigenemia pp65 assay. The cultures were stained at 18-24 h (first vial) and 72 h (second vial) with an indirect immunofluorescence assay with a monoclonal antibody against p72 CMV antigen. RESULTS: We studied 878 blood samples of which 247 (28.1%) were positive for CMV. Of the positive samples, 211 (85.4%) were detected in the first vial, and 220 (89%) in the second vial. Neither of the two vials detected all positive samples. An overall toxicity of 3%, in the positive samples, and 8.5% in positive samples was detected, respectively. Of the 28 toxic samples, 25.9% were detected in the first vial and 85.1% in the second (p < 0.001). The use of the second vial increased the number of positive samples in 14.5% (36 blood samples). CONCLUSIONS: In view of the results obtained in this study it would seem that, in order to obtain the maximum diagnostic yield in the isolation of CMV from LPMN of peripheral blood in immunosuppressed patients by means of the shell-vial culture, it is necessary to inoculate all the LPMN extracted into two vials. The lengthening of the incubation period up to 72 h for one of the vials leads to an increased in the isolation of CMV of 14.5% with a low overall toxicity.

Cytomegalovirus↗