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Objectives: The objective of this study was to investigate the silver gull as an indicator of environmental contamination by salmonellae and carbapenemase-producing Enterobacteriaceae (CPE) in south-east Australia., Methods: A total of 504 cloacal samples were collected from gull chicks at three nesting colonies in New South Wales, Australia [White Bay (n = 144), Five Islands (n = 200) and Montague Island (n = 160)] and were examined for salmonellae and CPE. Isolates were tested for carbapenemase genes and susceptibility to 14 antibiotics. Clonality was determined by PFGE and MLST. Genetic context and conjugative transfer of the carbapenemase gene were determined., Results: A total of 120 CPE of 10 species, mainly Escherichia coli (n = 85), carrying the gene blaIMP-4, blaIMP-38 or blaIMP-26 were obtained from 80 (40%) gulls from Five Islands. Thirty percent of birds from this colony were colonized by salmonellae. Most isolates contained the gene within a class 1 integron showing a blaIMP-4-qacG-aacA4-catB3 array. The blaIMP gene was carried by conjugative plasmids of variable sizes (80-400 kb) and diverse replicons, including HI2-N (n = 30), HI2 (11), A/C (17), A/C-Y (2), L/M (5), I1 (1) and non-typeable (6). Despite the overall high genetic variability, common clones and plasmid types were shared by different birds and bacterial isolates, respectively., Conclusions: Our data demonstrate a large-scale transmission of carbapenemase-producing bacteria into wildlife, likely as a result of the feeding habits of the birds at a local waste depot. The isolates from gulls showed significant similarities with clinical isolates from Australia, suggesting the human origin of the isolates. The sources of CPE for gulls on Five Islands should be explored and proper measures applied to stop the transmission into the environment., (© The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy.)

Objectives: Faecal Escherichia coli strains were isolated from great cormorants (Phalacrocorax carbo) and mallards (Anas platyrhynchos), which are commonly occurring waterbirds in Europe, and studied for resistance to cephalosporins and fluoroquinolones., Methods: Cloacal swabs or faeces from great cormorants and mallards in Central Europe were cultivated to isolate Escherichia coli strains with extended-spectrum β-lactamase (ESBL) and plasmid-mediated quinolone resistance (PMQR) genes., Results: Ten ESBL-producing E. coli with the bla(CTX-M-15) or bla(CTX-M-27) gene were isolated from eight great cormorants (1.6%, n = 499). The bla(CTX-M) genes were harboured by plasmids of F and I1 incompatibility groups. CTX-M-27-producing isolates were identified as the epidemiologically important B2-O25b-ST131 clone. No ESBL-producing E. coli was isolated from 305 mallards. Eight E. coli isolates with PMQR genes [six aac(6')-Ib-cr and two qnrS1] were detected in six great cormorants (1.2%). Seventeen strains with qnrS1 were detected in 17 mallards (6%). The PMQR genes were located on plasmids of incompatibility groups F, N or X2. ESBL and PMQR genes were found on conjugative plasmids, enabling the horizontal spread of resistance., Conclusions: Both great cormorants and mallards can spread epidemiologically important antimicrobial-resistant E. coli isolates to water bodies throughout Europe.

Objectives: The global occurrence of antibiotic resistance genes in bacteria in water environments is an increasing concern. Treated wastewater was sampled daily over a 45 day period from the outflow of a municipal wastewater treatment plant in Brno, Czech Republic, and examined for extended-spectrum β-lactamase (ESBL)-producing bacteria., Methods: Water samples were cultivated on MacConkey agar with cefotaxime (2 mg/L) and individual colonies were examined for ESBL production. Phenotypic ESBL-positive bacteria identified as Escherichia coli or Klebsiella spp. were tested for the presence of antibiotic resistance genes, the virulence gene afa/dra and the bla(CTX-M) upstream region. Genetic relatedness was analysed by PFGE, multilocus sequence typing and plasmid analysis., Results: A total of 68 ESBL-producing Enterobacteriaceae isolates were detected in 34 out of 45 wastewater samples. ESBL-producing isolates included 26 E. coli isolates, 4 Klebsiella pneumoniae isolates and 1 Klebsiella oxytoca isolate. The pandemic and multiresistant B2-O25b-ST131 clone was predominant, being detected among 19 E. coli isolates, and 17 of the B2-O25b-ST131 isolates were positive for the FIA replicon and the afa/dra operon and had an IS26 element flanking bla(CTX-M-15). Seventeen of the B2-O25b-ST131 isolates showed closely related PFGE profiles (defined by 84% band similarity) and belonged to identical clonal groups., Conclusions: The results highlight the inadequacy of the treatment process in removing multiresistant bacteria from municipal wastewater and point to a risk of transmission of clinically important multiresistant strains, such as the pandemic ST131 clone, to the environment. This is the first study demonstrating the pandemic ST131 clone in wastewater.

Objectives: The aim of this study was to determine the occurrence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli at an equine clinic and a horseback riding centre, and to discuss the impact of antimicrobial treatment on resistance selection., Methods: Faeces from horses, environmental smears and flies were sampled at both the clinic and riding centre. Staff at the equine clinic were also examined. The samples were cultivated on MacConkey agar with cefotaxime (2 mg/L) to isolate ESBL-producing E. coli. The presence of bla and qnr genes was tested by PCR, and transferability was determined by conjugation. Replicon typing and restriction analysis of plasmids harbouring ESBL and qnr genes were performed., Results: E. coli with the blaCTX-M-1 gene were isolated from horses, staff, environmental smears and flies at the two sites. E. coli isolates from the equine clinic harboured an IncHI1 conjugative 235-285 kb plasmid containing blaCTX-M-1, catA1, strA, sul2 and tet(B) genes. Some of these were positive for qnrS1 and/or qnrB19, and were located on 40 or 45 kb IncN or IncX1 conjugative plasmids. The gene blaCTX-M-1 in isolates from the riding centre was carried by IncN (30 kb) and IncI1 (85 kb) conjugative plasmids. Horizontal gene transfer seems to be involved in disseminating E. coli with ESBL and qnr genes at the clinic and riding centre., Conclusions: The study illustrates that ESBL-producing E. coli, as well as plasmids carrying ESBL genes of clinical interest, can be easily transferred among horses, humans and flies living in close contact.