Abstract:
The present study aims to investigate the suitability of the genus Aeromonas as a nonconventional
microbial indicator of water quality in different Egyptian water resources;
River Nile, drainage wastewater, and chlorinated drinking water. Aeromonas was
detected in 71.2% of examined samples, being maximum in drainage water and
minimum in River Nile and drinking water. Several positive significant relationships
between Aeromonas and the corresponding heterotrophic plate count, total coliforms,
fecal coliforms, and fecal streptococci were recorded, particularly in drainage water and
River Nile. 81.4% of presumptive Aeromonas species were identified as A. hydrophila. The
effect of seasonal variation showed maximum recovery in summer (61.5%) and spring
(28.9%) compared to autumn (5.8%) and winter (3.8%). The time needed to reduce the
population by 90% (T90) was 55 h and the calculated decay coefficient was 0.018 h 1.
The residual chlorine efficient to inactivate A. hydrophila in drinking water supplies
should be maintained at levels not less than 0.7mgL 1. Susceptibility of 72 isolates to
20 different antibiotics revealed recognizable multiple antibiotic resistance phenomenon
toward eight (40%) of the tested antibiotics. Sensitivity was mostly directed
to norfloxacin, ofloxacin, ceftriaxone, and cefotaxime. The study concluded that,
supplementing the traditional indicators index of water quality with Aeromonas levels
could be a simple, reliable, and inexpensive valid tool for better microbiological
characterization of water.