Introductory Chapter: Aeromonas, the Aquatic Multipotential Bacteria that May Affect Humans and Animals – An Overview of the Past to Face the Future

The genus Aeromonas embraces at present 36 species (Table 1), of which so far 19 are considered emerging pathogens to humans, producing a broad spectrum of infections, namely, gastroenteritis, wound and burn infections, urine infections, infections associated with leech therapy, surgical site infections, necrotizing fasciitis, pneumonia, meningitis, eye infections, intravascular gas production, epididymitis, and pyelonephritis [1][2][3][4][5].These bacteria tended to affect patients with hepatobiliary disease, especially those with cirrhosis, culminating in a rapid and fatal outcome [2].Using sequences of housekeeping genes (rpoD, gyrB, etc.) it has been demonstrated that only four species are the most abundant, embracing 95.4% of the identified strains: Aeromonas caviae (37.26%),Aeromonas dhakensis (23.49%),Aeromonas veronii (21.54%), and Aeromonas hydrophila (13.07%), and showed that A. hydrophila is not the most relevant species [1].In fact, A. dhakensis, a species previously misidentified as A. hydrophila, has emerged as a very relevant clinical species [6,7].The abundance of these species in clinical cases coincides with their capacity to induce a high expression of immune-related genes and cell damage in infected monocytes [8].A recent study by Yuwono et al. [9], using q-PCR detection of Aeromonas and other enteric pathogens from the feces of patients with gastroenteritis, showed that this genus was the second most common after Campylobacter.They found higher false-negative q-PCR results (11.73%) among samples with positive Aeromonas by culture than found for other enteric pathogens like Salmonella (8.75%), Campylobacter 1.1% and Shigella 0.1%.This could be due to the sensitivity and specificity of the target of the LightMix gastro-bacteria kit manufactured by TIB Molbiol (Berlin, Germany) for the detection of Aeromonas, an aspect that was not discussed in the paper [9].As it is well known Aeromonas are ubiquitous bacteria that infect humans and animals because their habitat is the aquatic freshwater and marine ecosystems, where they thrive, colonizing or infecting fish, mollusks, and other aquatic animals.Water-carrying Aeromonas can directly or indirectly be responsible for producing Aeromonas -A Ubiquitous Bacterium That Infects Humans and Animals