RESUMO
Abstract This is the first study of the genetic diversity of Moraxella spp. Isolates were detected in an Eye Hospital in the City of Buenos Aires. Due to the high frequency of Moraxella spp. observed in corneal abscesses, we decided to validate their identification at the species level, determine their drug susceptibility and perform molecular subtyping. Seventeen (17) isolates obtained from corneal abscesses were evaluated. The identification was carried out using a combination of biochemical tests and MALDI-TOF mass spectrometry. Of these isolates, 88.2% were identified as Moraxella lacunata, and 11.8% as Moraxella nonliquefaciens. Molecular subtyping was performed using the pulsed-field gel electrophoresis (PFGE) technique. All isolates were typable and thirteen digestion patterns were identified. Based on the obtained results, the PFGE technique using the SmaI enzyme can be used for epidemiological studies of strains of these species.
Resumen En este trabajo se presenta el primer estudio de diversidad genética de aislamientos de Moraxella spp. detectados en un hospital de oftalmología de la Ciudad Autónoma de Buenos Aires. Debido a la observación de una elevada frecuencia de Moraxella spp. en abscesos corneales, se decidió confirmar su identificación a nivel de especie, conocer su sensibilidad y realizar la subtipificación molecular. Se analizaron 17 aislamientos provenientes de abscesos corneales. La identificación se realizó mediante una combinación de pruebas bioquímicas y espectrometría de masas, MALDI-TOF MS. El 88,2% fueron identificados como Moraxella lacunata y el 11,8% como Moraxella nonliquefaciens. La subtipificación molecular se realizó por la técnica de electroforesis en gel de campo pulsado (PFGE). Todos los aislamientos fueron tipificables y se identificaron 13 patrones de digestión. Nuestros resultados muestran que la técnica de PFGE con la enzima SmaI es útil para hacer estudios epidemiológicos en cepas de estas especies.
RESUMO
This is the first study of the genetic diversity of Moraxella spp. Isolates were detected in an Eye Hospital in the City of Buenos Aires. Due to the high frequency of Moraxella spp. observed in corneal abscesses, we decided to validate their identification at the species level, determine their drug susceptibility and perform molecular subtyping. Seventeen (17) isolates obtained from corneal abscesses were evaluated. The identification was carried out using a combination of biochemical tests and MALDI-TOF mass spectrometry. Of these isolates, 88.2% were identified as Moraxella lacunata, and 11.8% as Moraxella nonliquefaciens. Molecular subtyping was performed using the pulsed-field gel electrophoresis (PFGE) technique. All isolates were typable and thirteen digestion patterns were identified. Based on the obtained results, the PFGE technique using the SmaI enzyme can be used for epidemiological studies of strains of these species.
Assuntos
Abscesso , Moraxella , Humanos , Moraxella/genética , Eletroforese em Gel de Campo Pulsado , Variação GenéticaRESUMO
Resumen Dolosigranulum pigrum es un coco gram positivo, anaerobio facultativo, que forma parte de la microbiota oral y del tracto respiratorio superior. Aunque los reportes de infecciones por este microorganismo son escasos, se lo ha asociado a un amplio espectro de enfermedades infecciosas. Se describe el caso de un hombre adulto con un absceso corneal del que se aisló D. pigrum. El microorganismo fue identificado por espectrometría de masas (MALDI-TOF MS) y secuenciación del gen 16S ARNr. A su vez, se logró la identificación presuntiva mediante pruebas fenotípicas claves, como la disposición en racimos en la coloración de Gram, la prueba negativa de la catalasa, la producción de pirrolidonil arilamidasa y leucina aminopeptidasa, el crecimiento en NaCl al 6,5% y la hidrólisis de esculina. Los datos de la literatura y el presente caso respaldan la asociación del microorganismo con infecciones oculares, a menudo de curso destructivo, principalmente en pacientes de edad avanzada.
Abstract Dolosigranulum pigrum is a gram-positive, facultatively anaerobic coccus, which is part of the oral and upper respiratory tract microbiota. Although reports of infections by this microorganism are scarce, it has been associated with a wide spectrum of infectious diseases. The case of an elderly man with a lower corneal abscess, in which Dolosigranulum pigrum was isolated, is described. The microorganism was identified by mass spectrometry (MALDI-TOF MS) and by the sequencingof the 16S rRNAgene. Furthermore, the presumptive identification of the causative agent was achieved by using key phenotypic tests such as the cluster arrangement in Gram stain, the negative catalase test, the production of pyrrolidonyl arylamidase and leucine aminopeptidase activity, the growth in 6.5% NaCl and esculin hydrolysis. The data from the literature (and the present case) support the association of the microorganism with ocular infections, which often take a destructive course, mainly in elderly patients.
RESUMO
Dolosigranulum pigrum is a gram-positive, facultatively anaerobic coccus, which is part of the oral and upper respiratory tract microbiota. Although reports of infections by this microorganism are scarce, it has been associated with a wide spectrum of infectious diseases. The case of an elderly man with a lower corneal abscess, in which Dolosigranulum pigrum was isolated, is described. The microorganism was identified by mass spectrometry (MALDI-TOF MS) and by the sequencing of the 16S rRNA gene. Furthermore, the presumptive identification of the causative agent was achieved by using key phenotypic tests such as the cluster arrangement in Gram stain, the negative catalase test, the production of pyrrolidonyl arylamidase and leucine aminopeptidase activity, the growth in 6.5% NaCl and esculin hydrolysis. The data from the literature (and the present case) support the association of the microorganism with ocular infections, which often take a destructive course, mainly in elderly patients.
Assuntos
Infecções por Bactérias Gram-Positivas , Cocos Gram-Positivos , Abscesso , Idoso , Carnobacteriaceae , Cocos Gram-Positivos/genética , Humanos , Masculino , RNA Ribossômico 16S/genéticaRESUMO
Pterins, heterocyclic compounds widespread in biological systems, are able to photoinduce oxidation of DNA and its components. In the present study, we have investigated the photosensitizing properties of pterin (Ptr), the parent compound of oxidized pterins, using bovine serum albumin (BSA) as target. Aqueous solutions of BSA were exposed to UV-A irradiation (350nm) in the presence of Ptr, under various experimental conditions. The photosensitized processes were followed by UV/vis spectrophotometry, an enzymatic method for H2O2 determination and electrophoresis (SDS-PAGE). We present data that demonstrate unequivocally that BSA is damaged by Ptr. Although association between Ptr and the protein was evidenced by steady-state and time-resolved fluorescence measurements, the photosensitized damage takes place via a purely dynamic mechanism, which involves an electron transfer from BSA to the triplet excited state of Ptr, formed after UV-A excitation.