Correlation between faecal indicator bacteria in diarrheagenic stools and hospital wastewaters: Implication on public health

Background: Hospital wastewaters contain blends of inorganic, natural constituents and contaminants that carry significant health risk when released directly into the environment. The aim of this study is to investigate the correlation between faecal indicator bacteria in diarrheagenic stools and wastewaters generated in University of Medical Sciences Teaching Hospital complex, Akure, Nigeria.Methodology: Quantification of faecal indicator bacteria was carried out on diarrheagenic faecal samples collected from 55 hospitalized patients and 68 wastewater samples from the medical laboratory science and laundry units of the hospital over of period of 12 weeks. Standard membrane filtration technique was performed using membrane intestinal enterococcus (m-ENT), membrane faecal coliform (m-FC), membrane lauryl sulphate (MLSA), eosin methylene blue (EMB) and Salmonella-Shigella (SS) agar plates, which were incubated at 37ºC for 24 hours (MLSA, EMB and SSA), 44ºC for 24 hours (m-FC); and 37ºC for 48 hours (m-ENT). Bacterial colonies on agar plates were counted and expressed as colony forming units (CFU) per 100ml of diarrheagenic stool and wastewater. Pearson’scorrelation analysis was used to determine the relationship between the level of faecal indicator bacteria in diarrheagenic stools and wastewaters at p<0.05 level of significance (and 95% confidence interval).Results: The faecal coliform counts (log 10 CFU/100ml) ranged from 1.18 to 1.54 in diarrheagenic stools, 1.32 to1.64 in laboratory wastewater and 1.08 to 2.19 in laundry wastewater. Escherichia coli count (log 10 CFU/100ml) ranged from 1.08 to 1.40 in diarrheagenic stools, 1.20 to 1.86 in laboratory wastewater and 0.30 to 1.81 in laundry wastewater. Intestinal enterococci count (log 10 CFU/100ml) ranged from 0 to 0.30 in diarrheagenic stools, 0.78 to 0.90 in laboratory wastewaters and 0.48 to 1.11 in laundry wastewaters. Pearson’s correlation co-efficient showed that all the faecal indicator bacteria count in diarrheagenic faecal samples exhibited positive correlation with those in laboratory wastewaters, but not with those from laundry wastewaters.Conclusion: The findings suggest that diarrheagenic stools should be properly disinfected after the performance of laboratory tests to prevent transmission of potential pathogens, and wastewater generated from hospitals should be treated prior to discharge into the environment, to prevent possible infections in the community. Keywords: Correlation, faecal indicator bacteria, public health, transmission, wastewate

Assessment of faecal contamination in selected concrete and earthen ponds stocked with African catfish, Clarias gariepinus

Background: Microorganisms constitute significant fraction of the aquatic ecosystem and have been reported to be the cause of emerging novel infectious diseases in aquacultural practices. The prevalence of infectious diseases has been observed to depend on the interaction between fish pathogens and the aquatic environment. This study was conducted to assess the levels of faecal pollution markers in catfish (Clarias gariepinus) and their growing waters in selected earthen and concrete ponds in the teaching and research fish farm of the Federal University of Technology, Akure (FUTA), Nigeria in the dry (February-April) and wet seasons (May-July) of the year. Methodology: Two earthen and 2 concrete ponds were randomly selected as sampling sites due to their frequent usage. A total of 120 grabs of catfishes from the earthen (n=60) and concrete (n=60) ponds, and 84 pond water samples from earthen (n=42) and concrete (n=42) ponds, were randomly collected over a 6-month period of study. Enteric bacteria count in the water and catfish samples were determined using membrane filtration and pour plate methods respectively. The physiochemical characteristics of the water samples were determined using standard methods. The rate of bioaccumulation of faecal indicator bacteria was obtained by dividing the log count of each organism in the catfish by the corresponding log count in the growing waters. Results: Faecal coliforms count (log10 CFU/100ml) in the catfish from concrete and earthen ponds ranged from 1.41 to 2.28 and 1.3 to 2.47, and in the growing waters; 1.43 to 2.41 and 1.50 to 2.80 respectively. There was positive correlation of faecal coliforms with alkalinity of water samples from the earthen (r=0.61) and concrete ponds (r=0.62). Salmonella and faecal coliforms had the highest and least bioaccumulation in catfish raised in earthen pond while Salmonella and enterococci had the highest and least bioaccumulation in catfish raised in concrete pond respectively. Faecal coliforms and Escherichia coli had the highest and least counts in water samples from the earthen pond during the dry and wet months while Salmonella and E. coli had the highest and least counts in water samples from the concrete pond during the dry and wet months. Conclusion: High levels of bacterial faecal pollution markers in water samples and catfishes from the earthen and concrete ponds are reported in this study. Physicochemical characteristics and seasonality played major roles in the rate of bioaccumulation of the faecal pollution markers in catfishes raised in both earthen and concrete ponds