Desarrollo y evaluación de una base de datos in house para la identificación rápida de Burkholderia contaminons por EM MALDI-TOF / Development and evaluation of an in-house database for quick identification of Burkholderia contaminans by MALDI-TOF MS

La espectrometría de masas (EM) (matrix assisted laser desorption ionization-time of flight) MALDI-TOF demostró ser una herramienta robusta para la identificación de numerosos grupos taxonómicos. No obstante, presenta limitaciones. Una ventaja clave de la técnica es la flexibilidad para la incorporación de espectros proteicos de microorganismos ausentes en la base de datos comercial. Dada la prevalencia de Burkholderia contaminans en los pacientes fibroquísticos en Argentina, y a que en ellos es crucial el diagnóstico microbiológico rápido y confiable, la EM MALDI-TOF surge como una herramienta estratégica. El objetivo del trabajo fue desarrollar una base de datos adicional con espectros peptídicos de aislamientos de referencia de B. contaminans. La misma demostró ser exitosa para la identificación del 97% de los aislamientos analizados. Por lo cual la EM MALDI-TOF con la base de datos extendida resultó ser una herramienta útil para la identificación y diferenciación de otras especies relacionadas a B. contaminans.

MALDI-TOF (matrix assisted laser desorption ionization-time of flight) mass spectrometry (MS) proved to be a robust tool for the identification of numerous taxonomic groups. However, it has limitations. A key advantage of this technique is the flexibility for the incorporation of protein profiles of microorganisms not included in the commercial database. Due to the prevalence of Burkholderia contaminans in fibrocystic patients in Argentina and the fact that rapid and reliable microbiological diagnosis is crucial in them, MALDI-TOF MS emerges as a strategic tool. The aim of this work was to develop an additional database with peptide spectra of reference isolates of B. contaminans. This database demonstrated to be successful for the identification of 97% of the isolates analyzed. Therefore, MALDI-TOF MS with the extended database was a useful tool for the identification and differentiation of other related species to B. contaminans.

Bacteriemia por Helicobacter cinaedi: presentación de los primeros casos descritos en Argentina / Helicobacter cinaedi bacteremia: Presentation of the first cases reported in Argentina

Se presentan 2 casos de bacteriemia por Helicobacter cinaedi. El primero se diagnosticó en un varón de 76 años y resultó secundario a la colocación de un acceso vascular; el segundo correspondió a un lactante febril de 37 días de vida, asociado a un cuadro de gastroen-terocolitis aguda. H. cinaedi es un microorganismo que presenta dificultad para desarrollarse en diferentes medios de cultivo y lograr su identificación a nivel de especie. En ambos casos fue fundamental la observación microscópica en fresco de las botellas de hemocultivo, la utilización de la espectrometría de masas y la posterior secuenciación del gen hsp60 para llegar a esa instancia. En los últimos anos se han informado infecciones por H. cinaedi con frecuencia creciente en otras partes del mundo. En este trabajo presentamos los primeros casos de bacteriemia por H. cinaedi documentados en Argentina.

Two cases of bacteremia caused by Helicobacter cinaedi are presented. The first case was diagnosed in a 76-year-old male patient, and was secondary to a vascular access device placement; the second case corresponded to a febrile infant of 37 days of life, and was associated with acute gastroenteritis. H. cinaedi is a microorganism difficult to grow in different culture media and also to identify to species level. In both cases, the microscopic observation of blood culture bottles, the use of mass spectrometry and the subsequent sequencing of the hsp60 gene were essential. In the recent literature, H. cinaedi infections are being reported more frequently. In this report we present the first documented cases of bacteremia caused by H. cinaedi in Argentina.

[Development and evaluation of an in-house database for quick identification of Burkholderia contaminans by MALDI-TOF MS]. / Desarrollo y evaluación de una base de datos in house para la identificación rápida de Burkholderia contaminans por EM MALDI-TOF.

MALDI-TOF (matrix assisted laser desorption ionization-time of flight) mass spectrometry (MS) proved to be a robust tool for the identification of numerous taxonomic groups. However, it has limitations. A key advantage of this technique is the flexibility for the incorporation of protein profiles of microorganisms not included in the commercial database. Due to the prevalence of Burkholderia contaminans in fibrocystic patients in Argentina and the fact that rapid and reliable microbiological diagnosis is crucial in them, MALDI-TOF MS emerges as a strategic tool. The aim of this work was to develop an additional database with peptide spectra of reference isolates of B. contaminans. This database demonstrated to be successful for the identification of 97% of the isolates analyzed. Therefore, MALDI-TOF MS with the extended database was a useful tool for the identification and differentiation of other related species to B. contaminans.

[Helicobacter cinaedi bacteremia: Presentation of the first cases reported in Argentina]. / Bacteriemia por Helicobacter cinaedi: presentación de los primeros casos descritos en Argentina.

Two cases of bacteremia caused by Helicobacter cinaedi are presented. The first case was diagnosed in a 76-year-old male patient, and was secondary to a vascular access device placement; the second case corresponded to a febrile infant of 37 days of life, and was associated with acute gastroenteritis. H. cinaedi is a microorganism difficult to grow in different culture media and also to identify to species level. In both cases, the microscopic observation of blood culture bottles, the use of mass spectrometry and the subsequent sequencing of the hsp60 gene were essential. In the recent literature, H. cinaedi infections are being reported more frequently. In this report we present the first documented cases of bacteremia caused by H. cinaedi in Argentina.

Helicobacter pylori bab genes during chronic colonization.

Helicobacter pylori BabA adhesin metastability could yield variants with potential for periodic activation and deactivation of their mediated adherence. babA/B or babB/A chimeras could play an important role in translational regulation. We investigated the frequency of different bab gene profiles in paired isolates from antrum and corpus recovered from patients with chronic gastritis. Isolates from 174 biopsies from 34 patients were included, and bab genes at the three common chromosomal loci were investigated. Inter-micro-niche variation was found in 1/4 patients, counting duplicate copies of babA or babB, babB/A or babA/B chimeras, opposite location of babA and babB or babC and babB, and absence of babB ATG translational codon. Truncated BabA was identified in 2/34 patients without inter-micro-niche variation. Isolates from 12/34 patients harbored babA/B or babB/A chimeras -either in one, several or all micro-niches indicating that chimera formation is a common mechanism to control BabA expression. To note, babA gene was absent in 11/34 patients, and in this population, babA/B chimeras which lack expression predominated over babB/A, able to exhibit Le(b) binding phenotype.