Lamata, M. (M.)
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- Estudio de la infección asociada a catéter intravascular durante el año 1998 en la Clínica Universitaria de Navarra at the University Clinic of Navarra(Universidad de Navarra, 2001) Leiva, J. (José); Lecaroz, M.C. (María Concepción); Pozo, J.L. (José Luis) del; Soler, M. (M.); Hernaez, S. (S.); Lamata, M. (M.)Purpose: To study the intravascular catheter related infections (CRI) since January of 1998 to January of 1999 in our hospital. Methods: We studied 540 catheter tips using a modified combination of the cuantitative method of Cleri and the semicuantitative method of Maki. The catheters were classified into two groups according to the presence or absence of criteria for CRI. Results: 74.5% of the retired catheters because of infection suspice did not satisfied criteria for CRI. 44.7% of the patients with criteria suffered a catheter-related bacteriemia while just 1.7% of the patients without criteria suffered a bacteriemia. The most common isolated microorganisms were coagulase-negative Staphylococci, Corynebacterium species and S. aureus. Discussion and Conclusions: At least, 74.5% of the patients with a suspice of catheter related infection could undergo a non invasive diagnosis procedure that would have showed that the catheter was not infected.
- Comparative analysis of selected methods for the assessment of antimicrobial and membrane-permeabilizing activity: a case study for lactoferricin derived peptides(BioMed Central, 2008) Brandenburg, K. (Klaus); Moriyon, I. (Ignacio); Leiva, J. (José); Jerala, R. (Roman); Sánchez-Gómez, S. (Susana); Andrä, J. (Jörg); Martinez-de-Tejada, G. (Guillermo); Blondelle, S.E. (Sylvie E.); Lohner, K. (Karl); Lamata, M. (M.)Growing concerns about bacterial resistance to antibiotics have prompted the development of alternative therapies like those based on cationic antimicrobial peptides (APs). These compounds not only are bactericidal by themselves but also enhance the activity of antibiotics. Studies focused on the systematic characterization of APs are hampered by the lack of standard guidelines for testing these compounds. We investigated whether the information provided by methods commonly used for the biological characterization of APs is comparable, as it is often assumed. For this purpose, we determined the bacteriostatic, bactericidal, and permeability-increasing activity of synthetic peptides (n = 57; 9-13 amino acid residues in length) analogous to the lipopolysaccharide-binding region of human lactoferricin by a number of the most frequently used methods and carried out a comparative analysis. RESULTS: While the minimum inhibitory concentration determined by an automated turbidimetry-based system (Bioscreen) or by conventional broth microdilution methods did not differ significantly, bactericidal activity measured under static conditions in a low-ionic strength solvent resulted in a vast overestimation of antimicrobial activity. Under these conditions the degree of antagonism between the peptides and the divalent cations differed greatly depending on the bacterial strain tested. In contrast, the bioactivity of peptides was not affected by the type of plasticware (polypropylene vs. polystyrene). Susceptibility testing of APs using cation adjusted Mueller-Hinton was the most stringent screening method, although it may overlook potentially interesting peptides. Permeability assays based on sensitization to hydrophobic antibiotics provided overall information analogous - though not quantitatively comparable- to that of tests based on the uptake of hydrophobic fluorescent probes. CONCLUSION: We demonstrate that subtle changes in methods for testing cationic peptides bring about marked differences in activity. Our results show that careful selection of the test strains for susceptibility testing and for screenings of antibiotic-sensitizing activity is of critical importance. A number of peptides proved to have potent permeability-increasing activity at subinhibitory concentrations and efficiently sensitized Pseudomonas aeruginosa both to hydrophilic and hydrophobic antibiotics.
- Frozen cancellous bone allografts: positive cultures of implanted grafts in posterior fusions of the spine(Springer Verlag, 2004) Beguiristain-Gurpide, J.L. (José Luis); Diaz-de-Rada, P. (Pablo); San-Julian, M. (Mikel); Barriga, A. (Andrés); Barroso, J.L. (José L.); Hernaez, S. (S.); Alfonso-Olmos-García, M. (Matías); Lamata, M. (M.); Villas-Tome, C. (Carlos)We have carried out a study on the behaviour pattern of implanted allografts initially stored in perfect conditions (aseptically processed, culture-negative and stored at -80 degrees C) but which presented positive cultures at the implantation stage. There is no information available on how to deal with this type of situation, so our aim was to set guidelines on the course of action which would be required in such a case. This was a retrospective study of 112 patients who underwent a spinal arthrodesis and in whom a total of 189 allograft pieces were used. All previous bone and blood cultures and tests for hepatitis B and C, syphilis and HIV (via PCR techniques) were negative. The allografts were stored by freezing them at -80 degrees C. A sample of the allograft was taken for culture in the operating theatre just before its implantation in all cases. The results of the cultures were obtained 3-5 days after the operation. There were 22 allografts with positive culture results (12%) after implantation. These allografts were implanted in 16 patients (14%). Cultures were positive for staphylococci coagulase negative (ECN) in 10 grafts (46%), Pseudomonas stutzeri in two grafts (9%), Corynebacterium jeikeium in two grafts (9%), staphylococci coagulase positive in two grafts (9%) and for each of the following organisms in one case each (4%): Corynebacterium spp., Actinomyces odontolyticus, Streptococcus mitis, Peptostreptococcus spp., Rhodococcus equi and Bacillus spp. No clinical infection was seen in any of these patients. Positive cultures could be caused by non-detected contamination at harvesting, storing or during manipulation before implantation. The lack of clinical signs of infection during the follow-up of our patients may indicate that no specific treatment different from our antibiotic protocol is required in the case of positive culture results of a graft piece after implantation.
- The enterococcal surface protein, Esp, is involved in Enterococcus faecalis biofilm formation(American Society for Microbiology, 2001) Cucarella, C. (Carme); Leiva, J. (José); Lasa, I. (Íñigo); Toledo-Arana, A. (Alejandro); Amorena, B. (Beatriz); Arrizubieta, M.J. (María Jesús); Penades, J.R. (José R.); Lamata, M. (M.); Solano, C. (Cristina); Valle, J. (Jaione)The enterococcal surface protein, Esp, is a high-molecular-weight surface protein of unknown function whose frequency is significantly increased among infection-derived Enterococcus faecalis isolates. In this work, a global structural similarity was found between Bap, a biofilm-associated protein of Staphylococcus aureus, and Esp. Analysis of the relationship between the presence of the Esp-encoding gene (esp) and the biofilm formation capacity in E. faecalis demonstrated that the presence of the esp gene is highly associated (P < 0.0001) with the capacity of E. faecalis to form a biofilm on a polystyrene surface, since 93.5% of the E. faecalis esp-positive isolates were capable of forming a biofilm. Moreover, none of the E. faecalis esp-deficient isolates were biofilm producers. Depending on the E. faecalis isolate, insertional mutagenesis of esp caused either a complete loss of the biofilm formation phenotype or no apparent phenotypic defect. Complementation studies revealed that Esp expression in an E. faecalis esp-deficient strain promoted primary attachment and biofilm formation on polystyrene and polyvinyl chloride plastic from urine collection bags. Together, these results demonstrate that (i) biofilm formation capacity is widespread among clinical E. faecalis isolates, (ii) the biofilm formation capacity is restricted to the E. faecalis strains harboring esp, and (iii) Esp promotes primary attachment and biofilm formation of E. faecalis on abiotic surfaces.
- Sellado antibiótico de catéteres intravasculares centrales. Presentación de un caso tipo y de un protocolo de sellado antibiótico(Servicio de Publicaciones de la Universidad de Navarra, 2002) Leiva, J. (José); Pozo, J.L. (José Luis) del; Santisteban, M. (Marta); García-del-Barrio, M.A. (M.A.); Lamata, M. (M.)El uso de catéteres intravasculares tunelizados centrales supone una aportación fundamental a la medicina moderna. La infección asociada a estos dispositivos es una de las causas más frecuentes de infección nosocomial en nuestro medio. La simple retirada de un catéter infectado puede ser suficiente para el control de la infección, sin embargo, en muchos casos esta retirada es problemática. En este trabajo se presenta un protocolo de sellado antibiótico aplicable a pacientes diagnosticados de infección asociada a catéter.