Browsing by Author "Labarca, J"

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    Adverse drug reactions (ADRs) in patients with HIV infection. A prospective study
    (DUSTRI-VERLAG DR KARL FEISTLE, 1999) Gonzalez Martin, G; Yanez, CG; Gonzalez Contreras, L; Labarca, J
    Aim A prospective drug surveillance method was used to monitor 50 ambulatory patients with HIV infection, who were controlled in the Sexual Transmission Disease Service at Dr. Sotero del Rio Hospital (Santiago, Chile). The aim of this work was to characterize and study the frequency, characteristics, and associated factors of the ADRs in HIV-infected patients. Patients and methods: Patients were interrogated once or twice a month by a clinical pharmacist, who consigned data concerning the drug prescribed by the physician, drug-related signs and symptoms, and the laboratory's parameters as renal, hepatic, hematological function, and biochemical test. The ADR probability was assessed for an algorithm. Results: The frequency of adverse drug reactions found in the group of patients studied was 32.0%. The dermatological, hepatic, and hematological systems were the most affected by adverse drug reactions. Trimethroprim-sulfamethoxazole and zidovudine were the drugs mainly associated with ADRs. Patients with lymphocytes CD4+ count of 200 or less, presented a higher frequency of ADRs. 48.5% of ADRs were classified as probable. Severe reactions were found in 18.5% of the patients, and moderate in 70.4%. 50% of patients with ADRs needed the withdrawal of the implicated drug, and an 18.5% dose decreased. 63% gf the ADRs were dose-independent, Conclusion: There was a higher frequency of ADRs in those patients with multiple-drug therapy, but the frequency of ADR was not associated with age, gender, or hematological test.
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    Coagulase-negative staphylococci
    (2004) García, P; Benítez, R; Lam, M; Salinas, AM; Wirth, H; Espinoza, C; Garay, T; Depix, MS; Labarca, J; Guzmán, AM
    Coagulase-negative staphylococci (CNS) are frequently isolated from blood cultures, where they may be only a contaminant or the cause of bacteraemia. Determining whether an isolate of CNS represents a true CNS bacteraemia is difficult, and there is no single criterion with sufficient specificity. The aim of this study was to assess those clinical, microbiological, pathogenic and genotypic features that characterize true CNS bacteraemia. Twenty patients having two or more blood cultures positive for CNS and 20 patients with only one positive blood culture were studied. Significant bacteraemia was defined according to clinical and laboratory criteria. Incubation time for blood cultures to become positive, macroscopic appearance of colonies, species determination, biotype, susceptibility to antimicrobials, PFGE pattern and adherence capacity were all studied. Clinical bacteraemia was present in 16/20 patients with two or more positive blood cultures and in 2/20 patients with only one positive blood culture. A significant difference was seen in the median time to positivity between the 18 clinical bacteraemias and 22 contaminations (23.6 versus 29.2 h; P = 0.04, Wilcoxon). There was also a significant difference between the two groups in the median absorbance of the slime test (1.36 versus 0.58; P = 0005). All significant bacteraemias with two or more positive blood cultures had the same species identified, the same antimicrobial susceptibility pattern and the same PFGE pattern. In two patients with true bacteraemia with only one positive blood culture, the incubation time for the culture to turn positive was <24 h and the slime production absorbance was >2.5. The most useful parameters for the diagnosis of true CNS bacteraemia for patients with two positive blood cultures were incubation time until positive, species identification, antimicrobial susceptibility pattern, slime production and PFGE pattern. For patients with only one blood culture positive for CNS, the useful parameters for prediction of true bacteraemia were incubation time until positive and slime production, both of which are simple, low-cost tests.
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    Pharmacokinetics of vancomycin in patients with severely impaired renal function
    (DUSTRI-VERLAG DR KARL FEISTLE, 1996) GonzalezMartin, G; Acuna, V; Perez, C; Labarca, J; Guevara, A; Tagle, R
    The pharmacokinetics of 1 g dose of intravenous vancomycin was studied in 8 patients with severe renal failure. Serum vancomycin levels were determined by fluorescence polarization immunoassay. After single dose of vancomycin peak concentrations ranged from 37.8 mu g.ml(-1) to 109.3 mu g. ml(-1) (mean 64.9 +/- 21.7 mu g.ml(-1)). Vancomycin trough concentration 168h after administration of the antibiotic ranged from 2.23 mu g.ml(-1) to 11.42 mu g.ml(-1) (mean 6.55 +/- 2.8 mu g.ml(-1)). The data were analyzed using a PCNONLINE computer program, and in all patients a triexponential model described how concentrations decreased in time. Three-compartment parameters obtained from the 8 patients were t(1/2) alpha = 0.312 +/- 0.242 h, t(1/2) beta 6.012 +/- 5.36 h, and t(1/2) gamma = 131.0 +/- 46.7 h. Vd = 0.158 +/- 0.121 1.kg(-1), Vdss = 0.920 +/- 0.248 1.kg(-1) and total Cl = 0.10 +/- 0.049 1.h(-1) per kg of weight. Between 1.5% and 21.2% of the administered vancomycin dose was eliminated during hemodialysis. The dialysis clearance of vancomycin ranged from 50.6 ml.min(-1) to 76.8 ml.min(-1) (average: 62.4 +/- 10.4 ml.min(-1)). However, after dialysis plasma concentrations returned to pre-dialysis values. In accordance to our kinetic study 1 g of vancomycin given every 7 days is adequate treatment for methicillin-resistant Staphylococcus aureus infections in patients with severe renal failure whose creatinine clearance is lower than 10 ml.min(-1).
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    Time course of antibody response to tetanus toxoid and pneumococcal capsular polysaccharides in patients infected with HIV
    (LIPPINCOTT WILLIAMS & WILKINS, 1998) Talesnik, E; Vial, PA; Labarca, J; Mendez, C; Soza, X
    The temporal course of the humoral immune response to T-cell-dependent and T-cell-independent type 2 antigens was evaluated in HIV-infected patients. In all, 26 seropositive patients were vaccinated with tetanus toroid and 23-valent pneumococcal vaccines; total IgG and IgG1 antibodies to tetanus toroid (Ttox) and total IgG and IgG2 antibodies against 23 Streptococcus pneumoniae capsular antigens (PPS) were measured at baseline, 2 months, and 12 months after vaccination. For the Ttox, baseline levels of IgG1 (Ttox-IgG1) increased from 11.0 to 19.5 mg/L at 2 months postimmunization. Overall only 6 patients (23%) showed a significant response. At 12 months postvaccination, Ttox-IgG and T-tox-IgG1 were significantly lower than baseline levels (Ttox IgG basal; 11.0 mg/L, 12 months; 0.8 mg/L, Ttox IgG1 baseline; 13.1 mg/L, Ttox IgG1 12 months; 2.4 mg/L) and in 10 patients, antibodies that fell below protective levels (0.6 mg/L). In contrast with PPS, a significant response was observed at 2 and 12 months (PPS-IgG basal; 35.9 U/ml, 2 months; 151.4 U/ml, 12 months; 59.7 U/ml; PPS-IgG2 baseline 20.3 U/ml, 2 months; 113.2 U/ml, 12 months; 51..9 U/ml). Overall, 19 patients (76%) showed an immune response to pneumococcal polysaccharides antigens. Immunization with the Ttox T-cell-dependent antigen fails to elicit a significant immune response and may induce inhibition of antibody production in HIV-infected patients. In contrast, immunization with a T-cell-independent type 2 antigen can cause the pneumococcal polysaccharides to induce significant immune response in a high proportion of HIV-infected patients.