No abstract

The use of bacteriophages as potential indicators of faecal pollution has recently been studied. The correlation of the number of bacterial indicators and the presence of three groups of bacteriophages, namely somatic coliphages (SOMCPH), F-RNA-specific phages (FRNAPH) and phages of Bacteroides fragilis (BFRPH), in raw and treated wastewater and sludge is presented in this study. Raw and treated wastewater and sewage sludge samples from two wastewater treatment plants in Athens were collected on a monthly basis, over a 2-year period, and analysed for total coliforms, Escherichia coli, intestinal enterococci and the three groups of bacteriophages. A clear correlation between the number of bacterial indicators and the presence of bacteriophages was observed. SOMCPH may be used as additional indicators, because of their high densities and resistance to various treatment steps.

Bacteria communicate with one another and with their host using chemical signalling molecules. This phenomenon is generally described as quorum sensing. A set of primers for PCR detection of Salmonella spp. has been designed using as target the sdiA gene which encodes a signal receptor of the LuxR family. The PCR product (274 bp) was confirmed by sequencing. A number of 81 non-Salmonella strains (representing 24 different species) were tested and gave negative results, while a total of 101 different serotypes of Salmonella (155 strains) tested positive for the presence of the sdiA gene. The sensitivity and specificity of the sdiA-based PCR assay were also checked in artificially contaminated human faecal samples. In this study, we demonstrate that quorum sensing genes can be successfully exploited as diagnostic markers.

The use of bacteriophages as potential indicators of faecal pollution has recently been studied. The correlation of the number of bacterial indicators and the presence of three groups of bacteriophages, namely somatic coliphages (SOMCPH), F-RNA specific phages (FRNAPH) and phages of Bacteroides fragilis (BFRPH), in raw and treated sludge is presented in this study. Raw and anaerobically digested sewage sludge samples from two wastewater treatment plants in Athens were collected on a monthly basis, over a 2-year period, and analyzed for total coliforms, E. coli, intestinal enterococci and the three groups of bacteriophages. A clear correlation between the number of bacterial indicators and the presence of bacteriophages was observed. E. coli concentrations of > or =10(3) cfus g(-1) and <10(3) cfus g(-1) comprise a threshold for the presence of FRNAPH and BFRPH, respectively. Likewise, intestinal enterococci concentrations of > or =10(4) cfus g(-1) and <10(3) cfus g(-1) comprise a threshold for the presence of FRNAPH and BFRPH, respectively. In the case of SOMCPH, it was not possible to define a threshold, since they were detected with the lowest observed indicator concentrations in all samples.

Screening of Greek nontyphoid salmonellae from 2000 to 2002 yielded three extended-spectrum ␤-lactamase (ESBL)-producing human isolates. Salmonella enterica serotype Brandenburg harbored a multiresistant SHV-5 gene-carrying plasmid. S. enterica serotype Blockley and S. enterica serotype Hadar harbored a TEM-52 gene-carrying plasmid. An S. enterica serotype Virchow strain producing plasmid-mediated CTX-M-32 was isolated twice from poultry end products. All ESBL plasmids were self-transferable and carried by clones currently common in Greece.Infection with nontyphoidal salmonellae (NTS) usually results in self-limiting diarrhea not requiring treatment. However, for bacteremia and severe focal infections, expandedspectrum cephalosporins (ESC) are indicated (7). Emergence of 3GC-resistant NTS strains producing potent ␤-lactamases was first noticed in North Africa in the late 1980s. So far, virtually all ␤-lactamase types found in ESC-resistant nosocomial enterobacteria have also been encountered in NTS. Highprevalence areas appear to be North Africa, Latin America, and various parts of Asia (12). A rise in the incidence of ESC-resistant NTS is also apparent in developed countries, the most notable example being the spread of CMY-producing NTS in the United States (5). Isolation of ESC-resistant NTS in Europe is still uncommon, though the number of relevant reports is increasing (12). ESC-resistant, extended-spectrum ␤-lactamase (ESBL)-producing Salmonella enterica serotype Typhimurium strains apparently associated with travel to or immigration from Eastern Europe have been sporadically isolated in Greece since 1994 (19, 21). In the present study, we describe domestic ESC-resistant NTS isolates derived from humans as well as animal products in Greece during the period from 2000 to 2002.Salmonella spp. clinical isolates were referred from the national hospitals to three reference centers, those in Athens, Thessaloniki, and Herakleion, Greece, where serotyping and susceptibility tests were performed. Animal, animal product, and animal feed isolates were similarly collected and analyzed by the State Veterinary Laboratory in Halkida, Greece. Further susceptibility testing, analysis of 3GC resistance mechanisms, and molecular typing were carried out in the Department of Microbiology, Medical School of Athens, Athens, Greece, on isolates from the Athens, Thessaloniki, and Halkida centers. These laboratories constitute the National Network for Enteric Pathogens, coordinated by the Hellenic Center for Infectious Disease Control (KEEL), which also collects data on the isolates, including recent travel of their hosts. The above-mentioned activities are part of the continuous surveillance of salmonellosis.Species identification was performed using API 20E (BioMerieux, Marcy l'Etoile, France), and serotyping was performed using commercial antisera (BioMerieux). For human strains (3,142 isolates were serotyped during the period from 2000 to 2002; 2,751 [88%] were from the Athens and Thessaloniki centers), randomly selected isolat...