Untitled

Funder

Organizational Unit

Publications

Ciprofloxacin resistance in domestic wastewater treatment plants

Publication . Manaia, Célia M.; Novo, Ana; Coelho, Bruno; Nunes, Olga C.

The potential of domestic wastewater treatment plants to contribute for the dissemination of ciprofloxacin-resistant bacteria was assessed. Differences on bacterial counts and percentage of resistance in the raw wastewater could not be explained on basis of the size of the plant or demographic characteristics of population served. In contrast, the treated effluent of the larger plants had significantly more heterotrophs and enterobacteria, including ciprofloxacin-resistant organisms, than the smaller (p<0.01). Moreover, longer hydraulic retention times were associated with significantly higher percentages of resistant enterobacteria in the treated effluent (p<0.05). Independently of the size or type of treatment used, domestic wastewater treatment plants discharged per day at least 1010–1014 colony forming units of ciprofloxacin-resistant bacteria into the receiving environment.

2010Journal article

Restricted access

Diversity and antibiotic resistance of aeromonas spp. in drinking and waste water treatment plants

Publication . Figueira, Vania; Vaz-Moreira, Ivone; Silva, Márcia; Manaia, Célia M.

The taxonomic diversity and antibiotic resistance phenotypes of aeromonads were examined in samples from drinking and waste water treatment plants (surface, ground and disinfected water in a drinking water treatment plant, and raw and treated waste water) and tap water. Bacteria identification and intra-species variation were determined based on the analysis of the 16S rRNA, gyrB and cpn60 gene sequences. Resistance phenotypes were determined using the disc diffusion method. Aeromonas veronii prevailed in raw surface water, Aeromonas hydrophyla in ozonated water, and Aeromonas media and Aeromonas puntacta in waste water. No aeromonads were detected in ground water, after the chlorination tank or in tap water. Resistance to ceftazidime or meropenem was detected in isolates from the drinking water treatment plant and waste water isolates were intrinsically resistant to nalidixic acid. Most of the times, quinolone resistance was associated with the gyrA mutation in serine 83. The gene qnrS, but not the genes qnrA, B, C, D or qepA, was detected in both surface and waste water isolates. The gene aac(6’)-ib-cr was detected in different waste water strains isolated in the presence of ciprofloxacin. Both quinolone resistance genes were detected only in the species A. media. This is the first study tracking antimicrobial resistance in aeromonads in drinking, tap and waste water and the importance of these bacteria as vectors of resistance in aquatic environments is discussed.

2011Journal article

Restricted access

Antibiotic resistance, antimicrobial residues and bacterial community composition in urban wastewater

Publication . Novo, Ana; André, Sandra; Viana, Paula; Nunes, Olga C.; Manaia, Célia M.

This study was based on the hypothesis that the occurrence of antimicrobial residues and antibiotic resistant bacteria in the sewage could be correlated with the structure and composition of the bacterial community and the antibiotic resistance loads of the final effluent. Raw and treated wastewater composite samples were collected from an urban treatment plant over 14 sampling dates. Samples were characterized for the i) occurrence of tetracyclines, penicillins, sulfonamides, quinolones, triclosan, arsenic, cadmium, lead, chromium and mercury; ii) antibiotic resistance percentages for tetracycline, sulfamethoxazole, ciprofloxacin and amoxicillin and iii) 16S rRNA gene-DGGE patterns. The data of corresponding samples, taking into account the hydraulic residence time, was analyzed using multivariate analysis. Variations on the bacterial community structure of the final effluent were significantly correlated with the occurrence of tetracyclines, penicillins, sulfonamides, quinolones and triclosan in the raw inflow. Members of the class Epsilonproteobacteria presented positive correlations with those antimicrobials, whereas negative correlations were observed with Beta and Gammaproteobacteria and Firmicutes. Antibiotic resistance percentages presented different trends of variation in heterotrophs/enterobacteria and in enterococci, varied over time and after wastewater treatment. Antibiotic resistance was positively correlated with the occurrence of tetracyclines residues and high temperature. A relationship between antibiotic residues, bacterial community structure and composition and antibiotic resistance is demonstrated. Further studies, involving more wastewater treatment plants may help to elucidate this complex relationship.

2013Journal article

Restricted access

Differential patterns of antimicrobial resistance in population subsets of Escherichia coli isolated from waste- and surface waters

Publication . Figueira, Vânia; Serra, Elizabete; Manaia, Célia M.

The species Escherichia coli comprises different subgroups with distinct phylogeny, physiology and ecology and, thus, presumably, with different roles in antimicrobial resistance dissemination. E. coli strains isolated from raw and treated municipal wastewater and from urban water streams were characterized in terms of phylogenetic groups, antimicrobial resistance patterns and the presence of class 1 and class 2 integrons. Our main objective was to investigate the contribution of the different phylo-groups in antimicrobial resistance dissemination in urban waters. Groups A and B1 were predominant in all types of water, evidencing, respectively, the lowest and the highest resistance prevalence. Municipal wastewater treatment was accompanied by significant increases of ciprofloxacin and streptomycin resistance (pb0.01). Antimicrobial resistance prevalence differed significantly between the different phylo-groups and within the same group, mainly in group A. Such differences contributed to explain the higher ciprofloxacin and streptomycin resistance rates observed in treated effluent in comparison with the raw wastewater. We conclude that the dynamics of the bacterial populations has a major role on the dissemination of antimicrobial resistance in the environment.

2011Journal article

Restricted access

Comparison of ubiquitous antibiotic-resistant Enterobacteriaceae populations isolated from wastewaters, surface waters and drinking waters

Publication . Figueira, Vânia; Serra, Elizabete A.; Vaz-Moreira, Ivone; Brandão, Teresa R. S.; Manaia, Célia M.

This study aimed at assessing the role of ubiquitous (non-Escherichia coli) Enterobacteriaceae in the dissemination of antimicrobial resistance through the urban water cycle. Enterobacteriaceae isolated from a municipal wastewater treatment plant (111 isolates), urban water streams (33 isolates) and drinking water (123 isolates) were compared in terms of: (i) genera distribution, (ii) resistance to 12 antibiotics, and (iii) class 1 and class 2 integrons. The predominant bacterial genera were the same in the different types of water, although with a distinct pattern of species. The most prevalent resistance phenotypes were observed for amoxicillin, ticarcillin, cephalothin and sulphamethoxazole (24–59% in the three types of water). No resistance against ceftazidime or meropenem was observed. Resistance to cephalothin, amoxicillin and sulphamethoxazole was significantly more prevalent in drinking water, water streams and wastewater, respectively, than in the other types of water. It was possible to recognize antibiotic-resistance associations, namely for the pairs streptomycin–tetracycline (positive) and ticarcillin–cephalotin (negative). Class 1 and/or class 2 integrons with similar gene cassettes were detected in the three types of water. This study demonstrated that Enterobacteriaceae are important vehicles of antibiotic resistance, namely in drinking water.

2012Journal article

Restricted access