Characteristics of an Aeromonas trota strain isolated from cerebrospinal fluid.

Aeromonas are ubiquitous in aquatic habitats. However some species can cause infections in humans, but rarely meningitis. Here we describe the isolation and characterization of an Aeromonas strain from cerebrospinal fluid of a meningitis patient. The isolate, identified as A. trota by biochemical and molecular methods, was susceptible to ampicillin but resistant to cephalothin and cefazolin. Genome sequencing revealed virulence factor genes such as type VI secretion system, aerolysin and lateral flagella. The isolate exhibited swarming motility, hemolytic activity and adhesion and cytotoxicity on HeLa cells. This is the first report of A. trota associated with meningitis and its virulence characteristics.

Utilization of carbon sources by clinical isolates of Aeromonas.

Bacteria in the genus Aeromonas are primarily aquatic organisms; however, some species can cause diseases in humans, ranging from wound infections to septicemia, of which diarrhea is the most common condition. The ability to use a variety of carbon substrates is advantageous for pathogenic bacteria. Therefore, we used Biolog GN2 microplates to analyze the ability of 103 clinical, predominantly diarrheal, isolates of Aeromonas to use various carbon sources, and we verified whether, among the substrates metabolized by these strains, there were some endogenous to the human intestine. The results indicate that Aeromonas present great diversity in the utilization of carbon sources, and that they preferentially use carbohydrates and amino acids as carbon sources. Among the carbon sources metabolized by Aeromonas in vitro, some were found to be components of intestinal mucin, including aspartic acid, glutamic acid, l-serine, galactose, N-acetyl-glucosamine, and glucose, which were used by all strains tested. Additionally, mannose, d-serine, proline, threonine, and N-acetyl-galactosamine were used by several strains. The potential to metabolize substrates endogenous to the intestine may contribute to Aeromonas' capacity to grow in and colonize the intestine. We speculate that this may help explain the ability of Aeromonas to cause diarrhea.

Impact of Aeromonas and diarrheagenic Escherichia coli screening in patients with diarrhea in Paraná, southern Brazil.

INTRODUCTION: A wide diversity of bacterial agents may cause diarrhea, presenting challenges to clinical laboratories to define a diagnosis. Considering that most stool cultures are negative, we screened stool samples from patients with diarrhea for the presence of 14 bacterial enteropathogens, aiming to establish which of them should be included in routine stool analysis. METHODOLOGY: Stool samples from 400 patients with diarrhea were analyzed for the presence of Salmonella, Shigella, Campylobacter, Aeromonas, Plesiomonas shigelloides, Vibrio, Yersinia enterocolitica, and diarrheagenic Escherichia coli using conventional microbiological methods and PCR. Two distinct samples were studied; one included predominantly patients involved in outbreaks, and the other patients of low socioeconomic status presenting sporadic cases of diarrhea. RESULTS: In total, 86 cultures (21.5%) were positive. Mixed infections were found in five patients, leading to recovery of 91 strains of enteropathogenic bacteria: Salmonella Enteritidis (9.2%), Aeromonas (7.2%), diarrheagenic E. coli (5.2%), and C. jejuni (1%). However, Salmonella predominated, with 11.5% frequency in diarrhea outbreaks, while Aeromonas predominated among patients of low socioeconomic status, with 14.6% frequency. CONCLUSION: Aeromonas and diarrheagenic E. coli, which are not routinely screened for, deserve to be included in laboratory screening panels.