María Teresa Ulloa

Community-acquired pneumonia in Chile: the clinical relevance in the detection of viruses and atypical bacteria

Background Adult community-acquired pneumonia (CAP) is a relevant worldwide cause of morbidity and mortality, however the aetiology often remains uncertain and the therapy is empirical. We applied conventional and molecular diagnostics to identify viruses and atypical bacteria associated with CAP in Chile. Methods We used sputum and blood cultures, IgG/IgM serology and molecular diagnostic techniques (PCR, reverse transcriptase PCR) for detection of classical and atypical bacteria (Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella pneumoniae) and respiratory viruses (adenovirus, respiratory syncytial virus (RSV), human metapneumovirus, influenza virus, parainfluenzavirus, rhinovirus, coronavirus) in adults >18 years old presenting with CAP in Santiago from February 2005 to September 2007. Severity was qualified at admission by Fines pneumonia severity index. Results Overall detection in 356 enrolled adults were 92 (26%) cases of a single bacterial pathogen, 80 (22%) cases of a single viral pathogen, 60 (17%) cases with mixed bacterial and viral infection and 124 (35%) cases with no identified pathogen. Streptococcus pneumoniae and RSV were the most common bacterial and viral pathogens identified. Infectious agent detection by PCR provided greater sensitivity than conventional techniques. To our surprise, no relationship was observed between clinical severity and sole or coinfections. Conclusions The use of molecular diagnostics expanded the detection of viruses and atypical bacteria in adults with CAP, as unique or coinfections. Clinical severity and outcome were independent of the aetiological agents detected.

Role of Neutralizing Antibodies in Adults With Community-Acquired Pneumonia by Respiratory Syncytial Virus

In a study of 356 adults with community-acquired pneumonia, respiratory syncytial virus was a frequent pathogen (13%). Serology and real-time reverse-transcription polymerase chain reaction improved the detection of repiratory syncytial virus. High respiratory syncytial virus serum-neutralizing antibody levels protected against severe pneumonia.

Poly(lactic acid)/TiO₂ nanocomposites as alternative biocidal and antifungal materials.

Poly(lactic acid) (PLA) composites with titanium oxide (TiO2) ~10-nm nanoparticles were produced by the melting process and their main properties were evaluated. The nanoparticles are homogeneously dispersed in the matrix with a low degree of agglomeration, as seen by transmission electron microscopy (TEM). The crystallinity temperature increased ~12% when 5 wt.% of TiO2 was added, showing that the nanoparticles acted as nucleating agents this trend was confirmed by optical images. The elastic modulus increased ~54% compared to neat PLA at 5 wt.% of nanoparticles. Despite these improvements, PLA/TiO2 nanocomposites showed lower shear viscosity than neat PLA, possibly reflecting degradation of the polymer due to the particles. Regarding biocidal properties, after 2h of contact the PLA/TiO2 composites with 8 wt.% TiO2 showed a reduction of Escherichia coli colonies of ~82% under no UVA irradiation compared to pure PLA. This biocidal characteristic can be increased under UVA irradiation, with nanocomposites containing 8 wt.% TiO2 killing 94% of the bacteria. The PLA/TiO2 nanocomposites with 8 wt.% were also 99.99% effective against Aspergillus fumigatus under the UVA irradiation.

Isla de patogenicidad de Vibrio parahaemolyticus en cepas chilenas clínicas y ambientales

, halofilica, motil y habita normal-mente en ambientes marinos. Las cepastoxigenicas de este vibrion causan un cuadro degastroenteritis aguda autolimitado, asociado fre-cuentemente al consumo de mariscos crudos. Lascepas toxigenicas se caracterizan por codificar ensu genoma para dos importantes factores devirulencia de este vibrion, la denominada hemoli-sina directa termoestable (TDH) y la hemolisinadirecta termoestable relacionada (TRH). Estas doshemolisinas se pueden encontrar simultaneamen-te o por separado en cepas toxigenicas de