Biochemical characterization of pathogenic bacterial species using Raman spectroscopy and discrimination model based on selected spectral features.

This study aimed to evaluate the differences in the Raman spectra of nine clinical species of bacteria isolated from infections (three Gram-positive and six Gram-negative species), correlating the spectra with the chemical composition of each species and to develop a classification model through discriminant analysis to categorize each bacterial strain using the peaks with the most significant differences. Bacteria were cultured in Mueller Hinton agar and a sample of biomass was harvested and placed in an aluminum sample holder. A total of 475 spectra from 115 different strains were obtained through a dispersive Raman spectrometer (830 nm) with exposure time of 50 s. The intensities of the peaks were evaluated by one-way analysis of variance (ANOVA) and the peaks with significant differences were related to the differences in the biochemical composition of the strains. Discriminant analysis based on quadratic distance applied to the peaks with the most significant differences and partial least squares applied to the whole spectrum showed 89.5% and 90.1% of global accuracy, respectively, for classification of the spectra in all the groups. Raman spectroscopy could be a promising technique to identify spectral differences related to the biochemical content of pathogenic microorganisms and to provide a faster diagnosis of infectious diseases.

Spectral model for diagnosis of acute leukemias in whole blood and plasma through Raman spectroscopy.

Acute leukemias are oncohematological diseases that compromise the bone marrow and have a complex diagnostic definition, leading to a high mortality when diagnosed late. This study proposed to determine the spectral differences between whole blood and plasma samples of healthy and leukemic subjects based on Raman spectroscopy (RS), correlating these differences with their resulting biochemical alterations and performing discriminant analysis of the samples (n = 38 whole blood and n = 40 plasma samples). Raman spectra were obtained using a dispersive Raman spectrometer (830-nm wavelength, 280-mW laser power, 30-s exposure time) with a Raman probe. The exploratory analysis based on principal component analysis (PCA) of the blood and plasma sample's spectra showed loading vectors with peaks related to amino acids, proteins, carbohydrates, lipids, and carotenoids, being the spectral differences related to amino acids and proteins for whole blood samples, and mainly carotenoids for plasma samples. Discriminant models based on partial least squares (PLS) and PCA were developed and classified the spectra as healthy or leukemic, with sensitivity of 91.9% (PLS) and 83.9% (PCA), specificity of 100% (both PLS and PCA), and overall accuracy of 96.5% (PLS) and 93.0% (PCA) for the whole blood spectra. In plasma, the sensitivity was 95.7% (PLS) and 11.6% (PCA), specificity of 98% (PLS) and 100% (PCA), and overall accuracy of 97.1% (PLS) and 64.1% (PCA). The study demonstrated that RS is a technique with potential to be applied in the diagnosis of acute leukemias in whole blood samples.

Prevalence of anemia in a sample of elderly southeastern Brazilians.

OBJECTIVE: To demonstrate the proportion of anemia and its association with demographic and clinical characteristics in a representative sample of elderly people from São José dos Campos, São Paulo. METHODS: Demographic data and blood samples were collected from 398 over 65-year-old male and female individuals. Anemia was defined as hemoglobin concentration <12g/dL in women and <13g/dL in men. Anemic and non-anemic groups were compared using the chi-squared test and a multiple logistic regression model. RESULTS: The prevalence of anemia was 18.6% (20.8% in men and 17.6% in women). The percentages of anemia rose significantly across the age groups >75-80, >85-90 and >90-95 years (p-value=0.0251). There were no significant differences in gender, ethnic background, place of residence, years of schooling, income, comorbidities and use of medications. According to gender, the mean hemoglobin concentration and mean corpuscular volume were 11.5g/dL (range: 8.4-11.9g/dL) and 90.7fL (range: 63.0-111.7fL) for women and 11.9g/dL (range: 8.6-12.8g/dL) and 92.1fL (range: 59.8-100.1fL) for men. The great majority of anemia cases were mild with less than 6% having hemoglobin concentrations below 10.9g/dL. Mean corpuscular volume was lower than 80fL in six cases (8%), between 80 and 100fL in 65 cases (88%) and higher than 100fL in three cases (4%). CONCLUSION: A total of 18.6% of elderly people from São José dos Campos had mild anemia with the majority being normocytic. The percentages of anemia rose as the age increased demonstrating an association between age and anemia.