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Instituto Nacional de Salud Pública

2003, Number 5

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salud publica mex 2003; 45 (5)

Microbiological indicators of water quality in the Xochimilco canals, Mexico City

Juárez-Figueroa LA, Silva-Sánchez J, Uribe-Salas FJ, Cifuentes-García E

Language: English
References: 17
Page: 389-395
PDF size: 174.62 Kb.


ABSTRACT

Objective. To quantify microbiology indicators of fecal contamination in the effluents of two waste water treatment plants and in samples collected in several canals in Xochimilco. Material and Methods. A cross sectional study was performed. Ten sites, 5 from plant effluents and 5 from canals, were selected for sampling during November and December 2001. Fecal coliforms and enterococci were quantified by membrane filtration, male specific (F+) and somatic coliphages by double agar layer technique, and Cryptosporidium oocysts and Giardia cysts by concentration with Envirocheck filter followed by immunofluorescence microscopy quantification.The average of organisms counts from effluents and canal water were compared with t Student test. Results. Treated water discharge in canals showed a low count of Fecal Coliforms (average 40.4/100 ml), enterococci (average 58.8/100 ml) and Cryptosporidium oocysts (average 13.2/100 l), while coliphages and Giardia cyst rendered higher counts (average 1467.5/100 ml and 1199.8/100 l, respectively) suggesting the water treatment methods could fail to remove these agents. A significant lower count of Giardia cysts (average 45/100 l) and no Cryptosporidium oocysts were found in irrigation canals, which suggest a natural clearance of these pathogens. Strains of Escherichia coli isolated in one of the canals contaminated with sewage had antimicrobial multi-resistance that was transferred by conjugation suggesting that resistance is encoded in a plasmid potentially transferable to other pathogenic bacteria. Conclusions. Cost effective and culturally acceptable waste treatment methods will require careful planning and consultation if they are to be adopted and mantained by local populations.


REFERENCES

  1. Ezcurra E. Mazari-Hiriart M. Are megacities viable? A cautionary tale from Mexico City. Environment 1996;38:6-35.

  2. World Health Organ. Health guidelines for the safe use of wastewater in agriculture and aquaculture. World Health Organ Tech Rep 1989. Ser 778.

  3. Valdespino J, Parrilla M, Sepúlveda J, Díaz J, Camacho M, Luna J. Calidad del agua en la ciudad de México en relación a los sismos de septiembre de 1985. Salud Publica Mex 1987;29:412-420.

  4. Cifuentes E, Gómez M, Blumenthal U, Téllez-Rojo M, Romieu I, Ruiz-Palacios G et al. Risk factors for Giardia intestinalis infection in agricultural village practicing wastewater irrigation in Mexico. Am J Trop Med Hyg 2000;62:388-392.

  5. Greenberg AE, Eaton AD. Standard methods for the examination of water and wastewater 20th. edition. American Public Health Association, American Water Works Association, Water Environment Federation. 1998.

  6. Adams M. Bacteriophages. Nueva York (NY). Interscience Pub, 1959.

  7. Rojas T. Chinampas: un legado. Mexico Indigena 1990; 6: 42-45.

  8. Coe MD. The Chinampas of Mexico. Scientific American 1964;211: 90-98.

  9. Jiménez-Osornio J, Del Amo S. An intensive Mexican traditional agroecosystem: The “chinampa”. Proceedings of the Sixth International Scientific Conference of the International Federation of Organic Agriculture Movements; 1986 August 18-21; Santa Cruz, California, USA.

  10. Hughes VM, Datta N. Conjugative plasmids in bacteria of the “preantibiotic“ era. Nature 1983;302:725-726.

  11. Neuwirth C, Siebor E, López J, Pechinot A, Kazmierczak G. Outbreak of TEM-24 producing Enterobacter aerogenes in an intensive care unit and dissemination of the extended-spectrum ß-lactamase to other members of the family Enterobacteriaceae. J Clin Microbiol 1996;34:76-79.

  12. Rosas I, Salinas E, Yela A, Calva E, Eslava C, Cravioto A. Escherichia coli in settled-dust and air samples collected in residential environments in Mexico City. Appl Environ Microbiol 1997;63:4093-4095.

  13. Harwood VJ, Whitlock J, Withington V. Classification of antibiotic resistance patterns of indicator bacteria by discriminant analysis: Use in predicting the source of fecal contamination in subtropical waters. Appl Environ Microbiol 2000; 66:3698-3704.

  14. Wiggins B, Andrews R, Conway R, Corr C, Dobratz E, Dougherty D et al. Use of antibiotic resistance analysis to identify nonpoint sources of fecal pollution. Appl Environ Microbiol 1999;65:3483-3486.

  15. Blumenthal UJ, Mara DD, Peasey A, Ruiz-Palacios G, Stott R. Guidelines for the microbiological quality of treated wastewater used in agriculture: Recommendations for revising WHO guidelines. Bull World Health Organ 2000;78:1104-1116.

  16. Leclerc H, Edberg S, Pierzo V, Delattre JM. Bacteriophage as indicators of enteric viruses and public health risk in groundwater. J Appl Microbiol 2000;88:5-21.

  17. International Association on Water Pollution, Research and Control. Study group on Health Related Water Microbiology. Water Res 1991;25:529-545.




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