Bacteriological and physico-chemical assessment of wastewater in different region of Tunisia: impact on human health

BMC Research Notes

Mahjoub Aouni¹  Mouna Hassine¹  Imen Ouardani¹  Imen Ben Salem¹ 

[1] Laboratoire des Maladies Transmissibles et Substances Biologiquement Actives - Université de Monastir, Tunisia

关键词: reclaimed wastewater;    microbiological quality;    pathotype;    Escherichia coli;    Enteropathogenic bacteria;   

Others  :  1167540
DOI  :  10.1186/1756-0500-4-144

 received in 2011-01-07, accepted in 2011-05-22,  发布年份 2011

【 摘 要 】

Background

In many parts of the world, health problems and diseases have often been caused by discharging untreated or inadequately treated wastewater. In this study, we aimed to control physico-chemical parameters in wastewater samples. Also, microbiological analyses were done to reveal Salmonella strains and each Escherichia coli (E.coli) pathotype.

Findings

Sixty wastewater samples were collected from fifteen different regions of Tunisia. All physico-chemical parameters (pH, residual free chlorine, total suspended solids, biological oxygen demand, and chemical oxygen demand) were evaluated.

For microbiological analyses, samples were filtered to concentrate bacteria. DNA was extracted by boiling and subjected to polymerase chain reaction (PCR) using different pairs of primers.

The mean pH values recorded for the sampling point were above the WHO pH tolerance limit. The total suspended solids (TSS) concentrations varied between 240 mg/L and 733 mg/L in entrance points and between 13 mg/L and 76 mg/L in exit points. In entrance points, the studied wastewater has an average COD concentration that varied between 795 mg/mL to 1420 mg/mL. Whereas, BOD concentration of the wastewater ranged between 270 mg/L to 610 mg/L. In exit points, COD concentration varied between 59 mg/L and 141 mg/L, whereas BOD concentration ranged from 15 mg/L to 87 mg/L.

The bacteriological control of wastewaters showed that, in entrance points, Escherichia coli (E.coli)was detected at the rate of 76.6%. Three E.coli pathotypes were found: ETEC (53.3%), EAEC (16.6%) and EIEC (6.6%).

Concerning the ETEC isolated strains, 8 of 16 (50%) have only the heat-labile toxin gene, 5 of 16 (31.2%) present only the heat-stable toxin gene and 3 of 16 (18.7%) of strains possess both heat-labile toxin gene and heat-stable toxin gene. In exist point, the same pathotypes were found but all detected ETEC strains present only the "est" gene.

Concerning Salmonella isolated strains; percentages of 66.6% and 20% were found in entrance and exit points respectively.

Conclusions

Wastewaters contain a large amount of pathogenic bacteria that present a real impact on human health. Assessment wastewater treatment stations have to consider in account enterobacterial pathogens as potential pathogens that should be correctly controlled.

【 授权许可】

   
2011 Salem et al; licensee BioMed Central Ltd.

【 图 表 】

Figure 1.

Figure 2.

【 参考文献 】

• [1]Balogh JC, Watson JR: Role and conservation of water resources. In Golf Course Management Construction. In Environmental Issues. Lewis Publishers, Boca Raton; 1992:17-35.
• [2]Global Water Supply and Sanitation Assessment: WHO and UNICEF. WHO/UNICEF/WSSCC. 2000. ISBN 92 4 156202 1. Pg 2, Box. 1.2
• [3]Rusin P, Enriquez CE, Jonson D, Yerba CP: Environmentally transmitted pathogens. In Environmental Microbiology. Edited by Maier RM, Pepper IL, Gerba CP. Academic Press, San Diego; 2000:447-489.
• [4]Fliermans CB: Ecology of Legionella: from data to knowledge with a little wisdom. Microbial Ecology 1996, 32:203-228.
• [5]Neumann M, Schulze-Robbecke R, Hagenau C, Behringer K: Comparison of methods for isolation of mycobacteria from water. Applied and Environmental Microbiology 1997, 63:547-552.
• [6]Nataro JP, Kaper JB: Diarrheagenic Escherichia coli. Clin Microbiol Rev 1998, 11:142-201.
• [7]Yates MV: Monitoring concerns and procedures for human health effects in Wastewater Reuse for Golf Course Irrigation, US Golf Association (ed.). Lewis Publishers, Boca Raton 1997, 143-171.
• [8]Olsen JE: Salmonella in Domestic Animals: Molecular typing of Salmonella. In CABI Publishing, CAB International, Wallingford/UK Edited by Wray C, Wray A. 2000, 429-446.
• [9]Riley LW: Molecular epidemiology of infectious diseases: principles and practices. ASM Press, Washington 2004, 337.
• [10]Caugant DABR, Levin I, Orskov F, Orskov C, Eden Svanborg, Selander RK: Genetic diversity in relation to serotype in Escherichia coli. Infect Immun 1985, 49:407-413.
• [11]Eisenstein BI: New molecular techniques for microbial epidemiology and the diagnosis of infectious diseases. J Infect Dis 1990, 161:595-602.
• [12]Selander RK, Caugant DA, Whittam TS: Genetic structure and variation in natural populations of Escherichia coli. In Escherichia coli and Salmonella typhimurium: cellular and molecular biology. Edited by Neidhardt FC, Ingraham KL, Magasanik B, Low KB, Schaechter M, Umbarger HE. American Society for Microbiology, Washington D.C; 1987:1625-1648.
• [13]Wachsmuth K: Molecular epidemiology of bacterial infections: examples of methodology and of investigations of outbreaks. Rev Infect Dis 1986, 8:682-692.
• [14]American Public Health Association: Standards methods for the examination of water and wastewater. American Public Health Association, Washington, D.C; 2005:21.
• [15]Ademoroti CMA: Standard method for water and Effluents Analysis. Foludex press Ltd, Ibadan 1996, 22-23. 44-54, 111-112
• [16]Rompre A, Servais P, Baudart J, de-Roubin MR, Laurent P: Detection and enumeration of coliforms in drinking water: current methods and emerging approaches. J Microbiol Methods 2002, 49:31-54.
• [17]Roger W, Pickup_y Glenn Rhodes, Hermon-Taylor John: Monitoring bacterial pathogens in the environment: advantages of a multilayered approach. Current Opinion in Biotechnology 2003, 14:319-325.
• [18]Waage AS, Vardund T, Lund V, Kapperud G: Detection of low numbers of Salmonella in environmental water, sewage and food samples by a nested polymerase chain reaction assay. J Appl Microbiol 1999, 87:418-428.
• [19]Gunzburg ST, Tornieporth NG, Riley LW: Identification of enteropathogenic Escherichia coli by PCR-based detection of the bundle-forming pillus gene. J Clin Microbiol 1995, 33:1375-1377.
• [20]Yamasaki S, Lin Z, Shirai H, et al.: Typing of verotoxins by DNA colony hybridization with poly and oligonucleotide probe a based-enzyme-linked immunosorbent assay and polymerase chain reaction. Microbiol Immunol 1996, 40:345-352.
• [21]Hornes E, Wasteson Y, Olsvik : Detection of Escherichia coli heat-stable enterotoxin genes in pig stool specimens by immobilized colorimetric, nested polymerase chain reaction. J Clin Microbiol 1991, 29:2375-2379.
• [22]Tamanai-Shacoori Z, Jolivet-Gougeon A: Detection of enterotoxigenic Escherichia coli in watter by polymerase chain reaction amplification and hybridization. Can J Microbiol 1994, 40:243-249.
• [23]Sethabutr O, Venkatesan M, Murphy GS, Eampokalap B, Hogoe CW, Echeverria P: Detection of shigellae and enteroinvasive Escherichia coli by amplification of the invasion plasmid antigen H DNA sequence in patients with dysentery. J Infect Dis 1993, 167:458-461.
• [24]Ratchtrachenchai O, Subpasu AS, Ito K: Investigation on enteroaggregative Escherichia coli infection by multiplex PCR. Bull Dep Med Sci 1997, 39:211-220.
• [25]Way Judy S, Josephson Karen L, Pillai Suresh D, Abbaszadegan Morteza, Gerba Charles P, Pepper Ian L: Specific detection of Salmonella Spp. by Multiplex Polymerase Chain Reaction. Applied and environmental microbiology 1993, 1473-1479.
• [26]DAWF and WRC: South Africa Water Quality Guideline 1: Domestic water use. Department of Water Affairs and Forestry, Pretoria 2nd edition. 1995.
• [27]Morrison GO, Fatoki OS, Ekberg A: Assessment of the impact of point source pollution from the Keiskammahoek sewage treatment plant on the keiskamma river. Water SA 2001, 27:475-480.
• [28]WHO: Guidelines for the safe use of wastewater, excreta and greywater. World Health Organization. Geneva; 2006.
• [29]Akin JC: Physicochemical Determination of Pollutants in Wastewater and Vegetable Samples along the Jakara Wastewater Channelin Kano Metropolis, Kano State, Nigeria. European Journal of Scientific Research 2008, 23(1):122-133.
• [30]Z Amxaka M, Piro Nchev AG, Muyim ANYO: Microbiological and physico-chemical assessment of the quality of domestic water sources in selected rural Communities of the Eastern Cape Province, South Africa. Water SA 2004, 30:333.
• [31]Ayati B: Investigation of sanitary and industrial wastewater effects on the Anzali reserved wetland. 2003.
• [32]Del Cerro A, Marquez I, Guijarro JA: Simultaneous detection of Aeromonas salmonicida, Flavobacterium psychrophilum, and Yersinia ruckeri, three major fish pathogens, by multiplex PCR. Appl Environ Microbiol 2002, 68:5177-5180.
• [33]Howard I, Espigares E, Lardelli P, Martin JL, Espigares M: Evaluation of microbiological and physicochemical indicators for wastewater treatment. Environ Toxicol 2004, 19:241-249.
• [34]Usera MA, Aladuen˜ a A, Diez R, De La Fuente M, Gutie'rrez R, Cerda' n P, Arroyo M, Gonza' lez R, Echeita A: Ana' lisis de las cepas de Salmonella spp aisladas de muestras clı'nicas de origen humano en Espan˜ a del 2000 (I). Bol Epidemiol Semanal 2001, 9:221-228.
• [35]Qadri Firdausi, Svennerholm Ann-Mari, Faruque ASG, Bradley Sack R: Enterotoxigenic Escherichia coli in Developing Countries: Epidemiology, Microbiology, Clinical Features, Treatment, and Prevention. Clinical Microbiology Reviews 2005, 465-483.
• [36]Gerba CP, Bitton G: Microbial pollutants: their survival and transport pattern to ground water. In Groundwater pollution microbiology. Edited by Bitton G, Gerba CP. John Wiley &Sons, NewYork; 1984:65-88.
• [37]Lawrence JR, Hendy MJ: Transport of bacteria through geologic media. Canadian journal of microbiology 1996, 42:410-422.
• [38]UNITED STATES ENVIRO NME NTAL PRO TEC TIO N AGE NCY (USE PA)[http://www.epa.gov/safewater/mcl.html] webcite 2004. [cited 2004 October 23]
• [39]U.S. EPA: In U.S. EPA, Offices of water and wastewater and Compliances (ed.) Guidelines for water reuse. Washington; 1992.
• [40]Clark CS: Potential and actual biological related health risks of wastewater industry employment. Journal Water Pollution Control Federation 1987, 59:999-1008.
• [41]Kindzierski XB, Gabos S: Health effects associated with wastewater treatment, disposal and reuse. Water Environment Research 1996, 68:818-826.