IStaphylococcus haemolyticus/I and IProvidencia vermicola/I Infections Occurring in Farmed Tilapia: Two Potentially Emerging Pathogens

• Published in: Animals (Basel) Vol. 13; no. 23
• Main Authors: Rajme-Manzur, David, Hernández-López, Jorge, Martínez-Porchas, Marcel, Vargas-Albores, Francisco, Garibay-Valdez, Estefanía, Coronado-Molina, Daniel Eduardo, Hernández-Oñate, Miguel Ángel, Vázquez-Ramírez, Francisco, Velázquez-Valencia, Luis Alfonso, Santacruz, Azucena
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.11.2023
• Subjects: Aquaculture; Aquaculture industry; Bacteria; Bacterial infections; Farms; Fish-culture; Fresh water; Oxytetracycline; Pathogenic microorganisms; Penicillin G; RNA; Mexico
• ISSN: 2076-2615; 2076-2615
• DOI: 10.3390/ani13233715

The development of the production of freshwater species such as Nile tilapia has favored the increase in larger-scale infectious outbreaks and new diseases in this industry. This work aimed to determine the presence of bacterial diseases in Nile tilapia cultured in Chiapas, Mexico. Blood and viscera samples were taken from healthy and sick animals from several commercial farms. The isolated bacteria were identified and characterized by different laboratory tests. The isolation, identification and characterization of two pathogens involved in an infectious process were achieved: Staphylococcus haemolyticus and Providencia vermicola. Both bacteria were cataloged as causal agents of diseases in tilapia farming in Mexico. This is the first report of bacterial diseases in tilapia farms caused by two rare but potentially emerging pathogens for the species. These results make it possible to know the health situation of the region, estimate economic losses, know the behavior of pathogens and propose effective prevention and control measures. This work aimed to determine the presence of bacterial pathogens in fish with a clinical picture suggestive of infectious disease in Nile tilapia reared in Chiapas, Mexico. Blood and viscera samples were taken from healthy and diseased animals from commercial farms. Clinical and pathological examinations of each individual were performed and samples were collected for bacteriological studies. The bacterial isolates were identified and characterized by culture, biochemical tests, antibiogram, challenge tests and 16S rRNA sequencing. Staphylococcus haemolyticus and Providencia vermicola were isolated from various diseased organisms. The clinical picture caused by Staphylococcus haemolyticus was characterized by appetite disorders, neurological signs, nodulation or ulceration in different areas and congestion or enlargement of internal organs. Providenciosis in juvenile specimens caused a characteristic picture of hemorrhagic septicemia. Challenge tests performed in healthy organisms revealed that both infections caused higher mortality rates in fish (p < 0.05) compared with non-infected specimens, with 100% survival. There was 100% mortality for animals infected with P. vermicola after three days post infection and 45% for those infected with S. haemolyticus. The isolation and identification of two pathogens involved in an infection process were achieved and cataloged as potential causal agents of disease outbreaks in tilapia farming in Mexico. This is the first report of possible bacterial infection caused by S. haemolyticus and P. vermicola in tilapia farms, which are two uncommon but potentially emerging pathogens for the species.