Bacterial indicators of pollution of the Douala lagoon, Cameroon: public health implications.

BACKGROUND Indiscriminate disposal of untreated wastes which are often heavily laden with sewage microorganisms some of which are pathogenic to humans into aquatic environments near cities could serve as potential dangers to human health. OBJECTIVE A prospective study was undertaken to investigate the scope of potential bacterial pathogens and to assess the extent of pollution of the Douala lagoon. METHODS A total of eighty water samples were collected fortnightly from the lagoon at five stations from March to October 2005 and analysed for heterotrophic bacterial densities, coliform counts, faecal coliform and faecal streptococcal counts. Bacteria were isolated and identified using standard microbiology and biochemical techniques. RESULTS High heterotrophic bacterial counts (33 x 10(5) - 161 x 10(5) CFU/ mL), total coliform counts (1.8 x 10(2) - 2.4 x 10(2) CFU/100 mL), faecal coliform counts (2.2 x 10(2) - 2.4 x 10(2) CFU/ 100 mL) and faecal streptococcal counts (2.1 x 102 - 2.3 x 10(2) CFU/100mL were observed in all sampling stations. Eleven species of bacteria: Bacteroides fragilis, Proteus vulgaris, Klebsiella pneumoniae, E. coli, Enterococcus faecalis, Enterobacter aerogenes, Citrobacter freundii, Aeromonas hydrophila, Pseudomonas aeruginosa, Bacillus mycoides and Serratia marcesens, were frequently isolated. CONCLUSION The presence of potential bacterial agents such as Bacteroides fragilis, Pseudomonas aeruginosa, Aeromonas hydrophila, Klebsiella pneumoniae and E. coli in the lagoon may pose a serious threat to the health and well being of users of the Lagoon and calls for urgent intervention.