Abstract: Consumption of contaminated fish lead to many of zoonotic bacterial diseases causes severe problems to human health. So, this study aimed to isolate some zoonotic bacteria from fish markets including E. coli, Pseudomonas, Salmonella spp., Staphylococcus spp. and Streptococci. This study was carried-out on four hundred samples of fish species classified as; Clarias gariepinus, Cyprinus carpio (common carp), Mugil cephalus and Oreochromis niloticu (tilapia) (100 of each). These fishes were obtained from different markets located in Eastern Delta governorates, Egypt. The fishes were subjected to clinical and bacteriological examinations to identify the types of bacterial isolates. The current results indicated that higher incidence of bacterial isolates was observed in Clarias garipinus, followed by common carp, Mugil cephalus and while low incidence was reported by O. niloticus. Although, Pseudomonas, Streptococci, Salmonella spp. recorded higher loads, while lower was reported by E. coli and Staphylococci were observed the public health impotence of zoonotic spp. Isolates were discussed.
INTRODUCTION
Fish is considered one of the most nutritive and highly desirable foodstuffs as fish meat has excellent nutritional value being rich in proteins, vitamins and unsaturated fatty acids. It is also extremely perishable and the safe consumption requires adequate sanitary conditions from the moment of catch, through preparation, sale and consumption (Alghabban, 2014). The most popular freshwater fish species in Egypt are Oreochromis niloticus, Bagrus bayad and Clarias lazera. The fish flesh, which is the main edible part, the majority of fish infections are usually related to exposed stress.
Most food borne illness caused by Salmonella spp., Staphylococcus spp. and Escherichia coli, usually related to fish consumption. Human infection by fish pathogens is usually through contact with abraded skin, with infected fish while handling or with water or other constituents of an aquatic environment (Acha and Szyfres, 2001; Gauthier, 2014).
In Egypt, Salmonellae, E. coli and Staphylococcus spp. are widely recognized as the principle causes of food poisoning outbreaks occurring due to consumption of contaminated fish and (Hassan and Fatin, 2003).
This study throws a light to detect some bacteria species of zoonotic importance from Nile Delta marketed fish as Clarias garipinus, Cyprinus carpio, Mugil cephalus and Oreochromis niloticu collected from Eastern Delta governorates, Egypt, to isolate E. coli, Pseudomonas, Salmonella spp., Staphylococcus spp. and Streptococci.
MATERIALS AND METHODS
Four hundred fish samples classified as Clarias garipinus, Cyprinus carpio, Mugil cephalus and Oreochromis niloticu (100 of each) were obtained randomly from different markets of Eastern Delta governorates in Egypt.
Clinical examination of fish was performed according to the method described by Schaperclaus (1993). Samples were taken from external body surface at the area between dorsal fin above the lateral line and another were taken from the ventral aspect of the pectoral fin using a sterile bacteriological loop, while sampling from internal organs were taken from liver, spleen, kidney and heart blood.
Surface swabs were aseptically taken from each fish and inoculated into separate sterile tube containing peptone water (1%). In addition, 5 g of fish sample flesh was desiccated in a sterile flask, under complete sterile condition and then 45 mL of sterile peptone water were added and thoroughly mixed using sterile blender for 1-1.5 min at 3000 rpm.
Bacterial isolates were identified by their cultural morphology and biochemical examination (identification) (Cruickshank et al., 1975; Collee et al., 1996).
The transmission of infection to cultured fish occurs through direct and indirect exposure to fish pathogens, which is facilitated by poor fish health management. The mechanisms by which fish diseases are generally transmitted including a mixture of the following, contaminated water supply, infected eggs or fish stocks and/or contaminated culture facilities, together with environmental conditions associated with the fish culture practice air, ponds, soil, equipment, feed and pollutants (Abd El Shahid et al., 2009; Lotfy et al., 2011; Aly, 2013).
Statistical analysis: Statistical analysis was carried-out using Chi-square test to detect the differences of the bacterial incidence among examined fish species according to SAS (2004).
RESULTS
The results recorded in Table 1 revealed significance difference (p<0.01) between bacterial isolates and fish species (O. niloticu and Clarias garipinus), while no significance difference was recorded in Cyprinus carpio and Mugil cephalus). The positive samples incidence was recorded in Pseudomonas spp. and followed by Streptococci spp. and Salmonella spp. while lower one was recorded by E. coli and Staphylococci spp. Regarding the results recorded in Table 1 Pseudomonas spp. showed high incidence (20%), while lower one recorded by E. coli and Staphylococci spp. Moreover, the site of examination revealed high incidence (10%) recorded by Streptococci spp. from internal organs while Pseudomonas spp. showed high incidence (16%) from internal organs. Meanwhile lower results (1%) were recorded by Streptococci spp. from internal organs and E. coli spp. from external surface.
| Table 1: | Incidence of bacterial species isolated from surface and internal organs in different examined fish species (n = 100) |
| Chi-square: 10.44**, Examined samples for each species: 100, $: Percentage of total samples | |
| Table 2: | Prevalence of bacterial isolates of zoonotic importance among different fish species |
| Chi-square: 32.55**, n: 100 samples for each fish species | |
Furthermore, the high incidence of bacterial isolates reveled from Clarias garipinus was Salmonella spp. and Streptococci spp. (20%), while E. coli (6%) recorded lower one. Regarding the site of examination, Salmonella spp. (16%) recorded the high incidence from the external surface, while the lower one from the same site was recorded by Pseudomonas spp. (3%). Meanwhile, the samples taken from internal organs revealed higher incidence (7%) by Pseudomonas spp., while lower one was recorded by E. coli spp. (2%).
Regarding the results recorded in Table 1 from Cyprinus carpio, the high incidence was reveled by Pseudomonas spp. (22%) followed by Streptococci spp. (18%) and the lower one was recorded by Staphylococci spp. (6%). Concerning the site of examination high incidence (12%) was revealed by Streptococci spp. and lower incidence (3%) by E. coli from external surface, while samples taken from internal organs reveled high incidence (15%) by Pseudomonas spp. and lower one was recorded by E. coli spp. and Staphylococci spp. (2% of each).
The results recorded in Table 1 concerning Mugil cephalus reveled high incidence (20%) by Pseudomonas spp. and the lower one was recorded by E. coli spp. (4%). Meanwhile, the samples taken from external surface showed higher incidence (10%) by Streptococci spp. and lower one by E. coli spp. (2%), while, higher incidence from samples taken from internal organs (12%) by Pseudomonas spp. while lower one was recorded by Staphylococci spp. (1%).
The Chi-square statistical results showed high significant results was indicated by O. niloticu and Clarias garipinus between site of examination and isolated bacteria, while no significant were recorded between fish species (Cyprinus carpio and Mugil cephalus) samples and site of examination and isolate bacteria.
The results recorded in Table 2 revealed the incidence of different zoontic bacteria that differ significantly among different fish species under the study. The higher incidence of bacterial isolates observed in Clarias garipinus (68%), followed by common carp (64%), Mugil cephalus (55%) and the lower bacterial incidences observed in O. niloticus (52%). The higher incidence of bacterial isolates observed in Pseudomonas (18%), Streptococci (17%), Salmonella spp. (13.75%) and the least incidence observed in E. coli (4.50%) and Staphylococci (6.50%).
DISCUSSION
Concerning the type of examined fish, it is clear that the higher bacterial incidence was observed in Clarias garipinus, common carp, Mugil cephalus and the lower bacterial incidence was observed in O. niloticus. These variations could be attributed to the fish species, environments and methods of catching and extent of handling during catching (Wang et al., 1994). In general, the presence of Enterobacteriaceae indicates unsatisfactory hygienic measures during catching and unsanitary condition of the fish environment (Valdivia-Garvayo et al., 1997). Pseudomonas spp. can cause septicemia in Oreochromis niloticus in Egypt that was more prevalent during winter period (El-Sayyad et al., 2010; Shayo et al., 2012). On the other hand, Newaj-Fyzul et al. (2008) illustrated that high prevalence of bacterial pathogens in tilapia especially Pseudomonas spp. (60.0%) and Staphylococcus spp. (p<0.05, χ2).
The presence of Enterobacteriaceae in fresh water fishes indicates a microbiological proliferation and multiplication of pathogenic and toxigenic micro-organisms constituting public health hazard. Generally, the presence of coliform in fish as E. coli serves as index of sanitation under which the fish is handled and associated with the faecal contamination. Such enteric bacteria were previously isolated with different percentages in freshwater from different fish species including Staphylococci, Salmonella, E. coli, Streptococci and Pseudomonas (Hassan, 1995; Austin and Austin, 2012).
The present results agree with those recorded by Heinitz et al. (2000), who reported that, Coliform do not seem to represent the normal flora of fish but presence indicate contamination when exposed to polluted water.
From results of the current study it is concluded that O. niloticus, showed higher incidence of Pseudomonas (4% internal, surface 16%), Streptococci (10% internal, surface 5%) Salmonella spp. (7% internal, surface 4%) and lower incidence observed by Staphylococci (2% internal, surface 1%) and E. coli (1% internal, surface 2%). The obtained results indicated higher incidence of bacterial isolates recorded in Clarias garipinus (68%), followed by common carp (64%) and Mugil cephalus (55%) and the lower incidence was in O. niloticus (52%). Generally, the higher incidence of bacterial isolates was recorded by, Pseudomonas (18%), Streptococci (17%), Salmonella spp. (13.75%) and the least incidence by E. coli (4.50%) and Staphylococci spp. (6.50%).
ACKNOWLEDGMENT
The authors acknowledge the support of Department of Fish and infective Disease, Faculty of Veterinary Medicine, Mansoura University for adopting this research study as a part of PhD thesis. Thanks also extended to the technical assistance of animal health research center, Cairo, Egypt.