Antibiotic resistance and survival of faecal coliforms in activated sludge system in a semi-arid region (Beni Mellal, Morocco)

Abstract

The activated sludge process is one of the biological treatment methods used in many countries to reduce the high levels of organic and mineral pollutants and pathogenic micro-organisms present in wastewater. The present work was undertaken to study the dynamic and antibiotic-resistance of faecal coliforms (FC) in the activated sludge system of Beni Mellal. This work has also as objective the study of the survival of FC, protozoan cysts, helminth eggs and FC antibiotic resistance in the sludge dehydrated in drying beds in order to know if the agricultural usage of sludge presents any problems to public health. The activated sludge treatment of Beni Mellal resulted in an average reduction of FC and faecal streptococci of 90.75 and 91.06%, respectively. The overall resistance (resistance to at least one antibiotic) of 111 FC strains isolated from the system was 72.07%. This treatment system did not increase the incidence of FC antibiotic resistance in treated wastewaters. The antibiotic resistance of FC was found to be similar in both raw (71.05%) and treated sewage (77.77%). High levels of antibiotic resistance were towards streptomycin (54.05%), ampicillin (42.34%), amoxicillin (42.34%) and amoxicillin-clavulanic acid (31.53%). The treatment of sludge in drying beds appeared to be efficient in eliminating pathogenic micro-organisms: FC, protozoan cysts and helminth eggs. Moreover, the FC antibiotic resistance did not change over time in sludgedrying bed. According to the standard norms, agricultural utilization of this sludge cannot be excluded. However, it is important to study in the receptor environment the survival and the behaviour of antibiotic-resistant FC present in sludge and water.

Determination of several potential virulence factors in non-o1 Vibrio cholerae, Pseudomonas aeruginosa, faecal coliforms and streptococci isolated from Marrakesh groundwater

“…The plates were prepared by adding the antibiotic to molten MullerHinton agar, previously cooled to 458C. Each plate was inoculated with the isolates using the multipoint inoculation method described by Oufdou et al (1999) andFars et al (2005) and incubated at 378C for 24 h. A control plate without antibiotic was prepared and similarly inoculated.…”

“…These antibiotics were chosen for two reasons: (i) they have been used in the treatment of human and/or livestock illnesses; and (ii) they have been used in previous surveys of antibiotic resistance in aquatic environments (Kelch & Lee 1978;Mezrioui & Oufdou 1996;Oufdou et al 1999;Fars et al 2005).…”

Are Sewage Treatment Plants Promoting Antibiotic Resistance?

“…Some researchers have observed little difference in bacterial resistance levels between raw and treated sewage (Espigares et al, 2006;Fars et al, 2005;Fontaine and Hoadley, 1976;Kümmerer et al, 1999;Martins da Costa et al, 2006). Others have concluded that in some instances, antibiotic resistance levels were reduced by the sewage treatment (Bell et al, 1983;Garcia et al, 2007;Guardabassi et al, 2002), contradicting findings that resistance levels can be proportionally elevated in treated effluent depending on the antibiotic, sewage treatment and bacterial genera under investigation (Andersen, 1993;da Silva et al, 2006; Downloaded by [Stony Brook University] at 08:58 20 December 2014 Gallert et al, 2005).…”

Freezing Inactivation of Escherichia Coli and Enterococcus Faecalis in Water: Response of Different Strains

“…Pathogenic and antibioticresistant microorganisms in WWTP effluents are a growing public health concern (George et al, 2002;Reinrhaler et al, 2003). Multiple antibiotic resistant fecal coliforms and enterococci including vancomycin resistant Enterococcus (VRE) have been detected in influent, effluent, and sludge from municipal wastewater treatment plants (Blanch et al, 2003;Caplin, et al, 2008;da Costa et al, 2006;Fars et al, 2005;Telabi et al, 2007;Vilanova and Blanch, 2005;Xu et al, 2007). The WWTPs provide a favorable environment for gene transfer because of high bacterial densities and nutritionally rich influent (da Costa et al, 2006;Silva, 2006;Xu et al, 2007).…”