Occurrence of Clostridium perfringens Types A, E, and C in Fresh Fish and Its Public Health Significance

Fish remains among the most traded of food commodities, and Egypt is one of the emerging countries being recognized as an important world fish exporter. Clostridium perfringens is an important foodborne pathogen to consider in fish trade, as it has been implicated as the causative organism of two fish outbreaks. The aim of the present study was to investigate the occurrence and toxin diversity of C. perfringens associated with fresh and canned fish and to examine the public health significance of C. perfringens infection in fish. Isolation and identification of C. perfringens showed a significantly higher prevalence of the bacterium in fresh fish collected from aquaculture (54.5%) and from markets (71%) as well as in humans in contact with fish (63%) compared with water used for keeping fresh fish (27.3%) and water used in canned fish (17.8%). The isolation level was significantly higher in samples from the external surface of fresh fish (31.8% in aquaculture, 45.6% in markets) than from the intestinal contents of the same fish (9.1% in aquaculture, 6.7% in markets). Thus, markets represent a risk factor for contamination of the external surface of fish from the surrounding environment. Genotyping of the C. perfringens-positive isolates by using multiplex PCR revealed that type A enterotoxin-negative (CPE-) is the predominant strain among fish (fresh and canned), humans, and water in contact with fresh fish. Interestingly, C. perfringens types A enterotoxin-positive (CPE+) and C were found only in fresh fish, and these two strains have great health importance in humans. Strikingly, C. perfringens type E strain was detected for the first time in fish, humans, and water in contact with fresh fish. Our results demonstrate for the first time that fish act as a reservoir for C. perfringens, particularly for types A CPE+, C, and E. The external surface of fish represents a vehicle for contamination of fish from the surrounding environment as well as a source of infection of humans, thereby representing a public health hazard.