Staphylococcus aureus Genetic Lineages Found in Urban Effluents and River Water

Methicillin resistant and susceptible Staphylococcus aureus (MRSA and MSSA respectively) remain a public health concern as human pathogens. Presence of MRSA and MSSA in river water and urban effluents was studied to analyze the S. aureus population and determine the genetic diversity and predominant genotypes obtained by spa types and MLST on each ecological niche. MRSA proportion in urban effluents was higher than in river water (P<0.05). According to the Simpson's Index of Diversity based on spa types, MSSA isolates were more diverse than MRSA isolates (P<0.05). Predominant spa types and STs detected in MSSA river water isolates were different from those found in urban effluents. In the MRSA population, ST125-t067 was the predominant genotype detected in both urban effluents (67.6%) and river water (82.4%). Overall, the MSSA and MRSA lineages most frequently found in river water and urban effluents were human associated clones (ST125-t067, ST5-t002; ST22-t032, ST30-t012 and ST15-t084). These results show the potential role of water in the S. aureus maintenance and dissemination. Association of isolates from the river with human ones could be reflecting the effect of anthropogenic activities in the ecosystems, which highlights the need to evaluate the circulation of pathogens in the environment via water.