Involvement of Panton–Valentine Leukocidin-Producing Staphylococcus aureus in Staphylococcal Skin Diseases in Patients in Peri-Urban Benin

## **Risk of Vibrio Transmission Linked to Consumption and Contact with Water in Benin**

**Bawa Boya1 , Hachim Mamadou1, Théodora A. Ahoyo1, and Lamine Saïd Baba Moussa1** 1Laboratory of Biology and Molecular Typing in Microbiology, Cotonou, Benin 2Engineering of Human Biology/Polytechnic School of Abomey-Calavi, Cotonou, Benin

Vibrio infections have increased in Benin, and this phenomenon is expected to increase due to climate

change, increased consumption of contaminated water, and the number of people who are immunocompromised. The objective of this study was to evaluate the risk of Vibrio transmission linked to the use of contaminated water in Benin. Water samples [n = 220] were analyzed to isolate Vibrio strains using their biochemical and cultural characteristics. The species were identified by the polymerase chain reaction technique by monitoring the search for genes encoding the cholera toxin of Vibrio cholerae [ctxA and ctxB] and the direct thermostable and thermostable hemolysins linked to Vibrio parahaemolyticus [tdh and trh].

Among the 220 collected samples, the biochemical tests revealed 86 strains of Vibrio species; Vibrio cholerae [35%], Vibrio parahaemolyticus [18.60%], and Vibrio alginolyticus [13.95%] were identified using a molecular tool; the presence of genes encoding the main virulence factors of the strains was studied. Thus 6.67%, 10%, and 3.33% of the strains of Vibrio cholerae, respectively, contain the toxins ctxA, ctxB, and the couple ctxA and ctxB. Likewise, the Vibrio parahaemolyticus strains contain 12.5% tdh toxins and 31.25% [tdh and trh].

The search for genes [tdh and trh] in Vibrio alginolyticus was also negative. A waterborne infection, cholera, is spread by ingesting food or water contaminated with bacteria. Human droppings may be predominant because, during sample collection, it was observed that areas of people frequently defecate in the wild. It is noted that the latrines and waste dumps are located in the immediate environment of some lakes, lagoons, and rivers sampled. Under these conditions, the contamination of the waters of lakes, lagoons, and rivers by rejected excreta is favored by runoff and infiltration of rainwater. Epidemics can be triggered by natural or fabricated events that contaminate drinking water or compromise access to safe drinking water and sanitation. The incidence of vibriosis is increasing, perhaps in part because of the spread of Vibrio species promoted by climate change and increasing water temperature.

Bawa Boya1, Hachim Mamadou1, Théodora A. Ahoyo2, and Lamine Saïd Baba Moussa1

1 Laboratoire de Biologie et de Typage Moleculaire en Microbiologie; Universite d'Abomey-Calavi, 05 BP 1604 Cotonou, Benin 2 Genie de Biologie Humaine, Ecole Polytechnique d'Abomey-Calavi; Universite d'Abomey-Calavi, BP 2009 Cotonou, Benin

#### Introduction

Vibrio infections have increased in Benin, and this phenomenon is expected to increase due to climate change, increased consumption of contaminated water and the number of people who are immunocompromised. The objective of this study was to evaluate the risk of Vibrio transmission linked to the use of contaminated water in Benin.

#### Methodology

Water samples [n = 220] were analyzed to isolate Vibrio strains using their biochemical and cultural characteristics. The species were identified using the Polymerase Chain Reaction technique by monitoring the search for genes encoding the cholera toxin of Vibrio cholerae [ctxA and ctxB] and the direct thermostable and thermostable hemolysins linked to *Vibrio parahaemolyticus [tdh and trh].*

*Table 1. List of primers used for the molecular characterization of Vibrio strains*



#### Results

The results of the incidence of Vibrio and other strains in the different communes are summarized in Figures 2 and 3. Thus, it appears that the collected water samples were contaminated by Citrobacter freundii (17.73%), Vibrio spp (32.73%), Proteus spp (20.45%), Salmonella spp (28.18%) and Escherichia coli (23.18%). The lowest rate of Vibrio spp (15%) was obtained in the communes of Athieme and Seme-Podji, while a high rate of Vibrio spp (65%) was obtained in the commune of Savalou. In addition, Salmonella sp. was highly identified (60%) in the samples collected in the municipality of Aguegue. Concerning the Escherichia coli strains, they were highly isolated from the samples collected in the northern (85% for Parakou and 55% for Djougou) part of the country.

#### Molecular Identification of Vibrio species

Of the 86 strains of Vibrio isolated from sampled waters, 13.95% belonged to the species V. alginolyticus, 18.60% to the species V. parahaemolyticus, 35% to the species V cholerae and 32.56% to the species Vibrio spp.

Acknowledgements : The authors express their gratitude to the LBTMM staff for their contribution to this study.

#### Distribution of Virulence Factors in Vibrio Species

The genes encoding major virulence factors, cholera toxins of V. cholerae [ctxA and ctxB] and the direct and thermostable heat- stable hemolysins of V. parahaemo- lyticus [tdh and trh] were detected in strains of V. cholerae and V. parahaemolyticus, which we characterized using PCR. Thus, the characterized Vibrio cholerae strains harbored the gene encoding for ctxA [6.67%], ctxB [10%] and the couple ctxA-ctxB [3.33%] toxins [Figure 1]. Likewise, the 12.5% V. parahaemolyticus strains contained the encoding for tdh toxins and 31.25% of them harbored both tdh and trh [Figure 2]. The search for genes [tdh and trh] in V. alginolyticus was also negative.

#### Conclusions

Epidemics can be triggered by natural or fabricated events that contaminate drinking water or compromise access to safe drinking water and sanitation. The incidence of vibriosis is increasing, perhaps in part because of the spread of Vibrio species promoted by climate change and increasing water temperature.

Keywords: water; Vibrio species; polymerase chain reaction; virulence genes; bacterial resistance
