Genotypic Diversity and Pathogenic Potential of Clinical and Environmental Vibrio parahaemolyticus Isolates From Brazil

Abstract

Vibrio parahaemolyticus strains recovered from human diarrheal stools (one in 1975 and two in 2001) and environmental sources (four, between 2008 and 2010) were investigated for the presence of virulence genes (trh, tdh, and vpadF), pandemic markers (orf8, toxRSnew), and with respect to their pathogenic potential in two systemic infection models. Based only on the presence or absence of these genetic markers, they were classified as follows: the environmental strains were non-pathogenic, whereas among the clinical strains, the one isolated in 1975 was pathogenic (non-pandemic), and the other two were pathogenic (pandemic). The pathogenic potential of the strains was evaluated in mice and Galleria mellonella larvae infection models, and except for the clinical (pathogenic, non-pandemic) isolate, the others produced lethal infection in both organisms, regardless of their source, serotype, and genotype (tdh, orf8, toxRSnew, and vpadF). Based on mice and larval mortality rates, the strains were then grouped according to virulence (high, intermediate, and avirulent), and remarkably similar results were obtained by using these models: The clinical strain (pathogenic and non-pandemic) was classified as avirulent, and other strains (four non-pathogenic and two pandemic) were considered of high or intermediate virulence. In summary, these findings demonstrate that G. mellonella larvae can indeed be used as an alternative model to study the pathogenicity of V. parahaemolyticus. Moreover, they raise doubts about the use of traditional virulence markers to predict pathogenesis of the species and show that reliable models are indispensable to determine the pathogenic potential of environmental isolates considered non-pathogenic, based on the absence of the long-standing virulence indicators.

Vibrio Species in an Urban Tropical Estuary: Antimicrobial Susceptibility, Interaction with Environmental Parameters, and Possible Public Health Outcomes

“…For example, Xu and colleagues (2015) reported that 14% of clinical isolates harbored neither genes, that is, these strains would conventionally be classified as avirulent [ 42 ]. Even though hemolysins alone can cause symptoms on the host, other virulence factors may play an important role, such as proteases, siderophores, biofilm-forming ability, and secretion systems [ 40 , 42 , 43 , 44 ]. It is also worth mentioning that the pathogenic potential of Vibrio spp.…”

Vibriosis and its impact on microbiological food safety

“…(Ramos et al, 2012) Oyster V. parahaemolyticus and V. vulnificus (ND) Florianópolis, SC (Ramos et al, 2014) Oyster V. parahaemolyticus (35%), V. vulnificus (10%), V. alginolyticus (7%) and V. fluvialis (2%) Mollusc farming water V. parahaemolyticus (45%), V. alginolyticus (29%) and V. vulnificus (13%) Florianópolis, SC (Silva et al, 2016a) Oyster and mussel V. parahaemolyticus (~ 11%) Shellfish farming water V. parahaemolyticus (18%) Lagoa dos Patos, RS (Rosa et al, 2016) Fish V. parahaemolyticus (<1%) Lagoa dos Patos, RS (Rosa et al, 2017) Fish V. parahaemolyticus (3.3%) Lagoa dos Patos, RS (Silveira et al, 2019) Fish Vibrio spp. (68%) and V. vulnificus (0.01%) Southeast region Rio de Janeiro, RJ (Oliva et al, 2016) Mussel V. parahaemolyticus (44.7%), V. alginolyticus (19.6%) and V. vulnificus (12.4%) Rio de Janeiro, RJ (Bouzas, 2021) Mussel V. parahaemolyticus (ND) Rio de Janeiro (Santos et al, 2021) Oyster farm V. parahaemolyticus (ND) Northeast region Baía de Todos os Santos, BA (Rodrigues & Carvalho, 2011) Oyster V. parahaemolyticus (ND)…”

Antibiotic and Heavy Metal Susceptibility of Non-Cholera Vibrio Isolated from Marine Sponges and Sea Urchins: Could They Pose a Potential Risk to Public Health?

“…All primer sequences and amplification conditions were taken from their respective references ( Table S2 ). Genomic DNA from strains of Vibrio parahaemolyticus IOC 17381 ( toxR + and tdh + ) and 0798081 ( trh + ) were used as positive controls for the respective virulence genes targeted by PCR [ 35 ]. Amplicons were observed through 1–2% agarose gel electrophoresis using the Low DNA Mass Ladder (Thermo Fisher Scientific, Waltham, MA, USA) as the molecular size standard.…”