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• Implementation of a National Integrated surveillance antimicrobial resistance program based on public-private partnership.• Description of good practices in building an integrated surveillance program on antimicrobial resistance that could be used by other countries.• Provide information to conduct risk assessment studies on antimicrobial resistance in Colombia to support policy making.

BackgroundEscherichia coli producing ESBL/AmpC enzymes are unwanted in animal production chains as they may pose a risk to human and animal health. Molecular characterization of plasmids and strains carrying genes that encode these enzymes is essential to understand their local and global spread.ObjectivesTo investigate the diversity of genes, plasmids and strains in ESBL/AmpC-producing E. coli from the Colombian poultry chain isolated within the Colombian Integrated Program for Antimicrobial Resistance Surveillance (Coipars).MethodsA total of 541 non-clinical E. coli strains from epidemiologically independent samples and randomly isolated between 2008 and 2013 within the Coipars program were tested for antimicrobial susceptibility. Poultry isolates resistant to cefotaxime (MIC ≥ 4 mg/L) were screened for ESBL/AmpC genes including blaCTX-M, blaSHV, blaTEM, blaCMY and blaOXA. Plasmid and strain characterization was performed for a selection of the ESBL/AmpC-producing isolates. Plasmids were purified and transformed into E. coli DH10B cells or transferred by conjugation to E. coli W3110. When applicable, PCR Based Replicon Typing (PBRT), plasmid Multi Locus Sequence Typing (pMLST), plasmid Double Locus Sequence Typing (pDLST) and/or plasmid Replicon Sequence Typing (pRST) was performed on resulting transformants and conjugants. Multi Locus Sequence Typing (MLST) was used for strain characterization.ResultsIn total, 132 of 541 isolates were resistant to cefotaxime and 122 were found to carry ESBL/AmpC genes. Ninety-two harboured blaCMY-2 (75%), fourteen blaSHV-12 (11%), three blaSHV-5 (2%), five blaCTX-M-2 (4%), one blaCTX-M-15 (1%), one blaCTX-M-8 (1%), four a combination of blaCMY-2 and blaSHV-12 (4%) and two a combination of blaCMY-2 and blaSHV-5 (2%). A selection of 39 ESBL/AmpC-producing isolates was characterized at the plasmid and strain level. ESBL/AmpC genes from 36 isolates were transferable by transformation or conjugation of which 22 were located on IncI1 plasmids. These IncI1 plasmids harboured predominantly blaCMY-2 (16/22), and to a lesser extend blaSHV-12 (5/22) and blaCTX-M-8 (1/22). Other plasmid families associated with ESBL/AmpC-genes were IncK (4/33), IncHI2 (3/33), IncA/C (2/33), IncΒ/O (1/33) and a non-typeable replicon (1/33). Subtyping of IncI1 and IncHI2 demonstrated IncI1/ST12 was predominantly associated with blaCMY-2 (12/16) and IncHI2/ST7 with blaCTX-M-2 (2/3). Finally, 31 different STs were detected among the 39 selected isolates.ConclusionsResistance to extended spectrum cephalosporins in E. coli from Colombian poultry is mainly caused by blaCMY-2 and blaSHV-12. The high diversity of strain Sequence Types and the dissemination of homogeneous IncI1/ST12 plasmids suggest that spread of the resistance is mainly mediated by horizontal gene transfer.

been removed from the soil by leaching or via harvested crops (Granados et al., 1993). Acidic soils, therefore, Soil acidity reduces maize (Zea mays L.) yields by up to 70% on generally have a low pH, contain toxic levels of Al and 8 million hectares in developing countries. Several breeding programs have produced populations better adapted to these conditions. TheMn, and are deficient in Ca, Mg, P, K, and Mo. These objectives of this study were to evaluate these populations for both characteristics limit the fertility of acid soils and inhibit per se cultivation and the development of new breeding germplasm. root development, leading to low water and nutrient up-To do so, we generated a diallel cross design, which included six acid take and low maize yields (Duque-Vargas et al., 1994). soil-tolerant and five susceptible populations with high yield potential Soil amendments (the application of lime and fertilizor tolerance to other stresses. Populations and crosses were evaluated ers) have been used to bring acid soils under agricultural in five environments, on acidic Al-toxic soils and in comparable limed production. However, such solutions may not be envisoils in Guadeloupe, Cameroon, and Colombia. Soil acidity decreased ronmentally friendly, have only a temporary effect, and grain yield by 46 to 73%, depending on the location and year. Signifiare too expensive for poor farmers in developing councant genotype ϫ soil condition interactions were observed for grain tries (The et al., 2001). The use of acid soil-tolerant maize yield. Mid-parent heterosis for yield was significantly higher in acid soils (32%) than in nonacid soils (20%). This suggests that the develop-cultivars provides an environmentally friendly, inexpenment of variety crosses between acid soil-tolerant populations could sive, and permanent solution, contributing to sustainbe used to increase maize yields in acid-soil cropping systems. The able crop production on acid soils (Granados et al., observed high general combining ability (GCA) for yield variation of 1993). the crosses in acid soil and its close relationship to per se performance Considerable genetic variation in acid-soil tolerance suggest that parental populations of variety crosses could be efficiently has been reported in maize. Early studies demonstrated screened on the basis of per se performance in acid soil.

The objective of this study was to determine Salmonella counts, serovars, and antimicrobial-resistant phenotypes on retail raw chicken carcasses in Colombia. A total of 301 chicken carcasses were collected from six departments (one city per department) in Colombia. Samples were analyzed for Salmonella counts using the most-probable-number method as recommended by the U.S. Department of Agriculture, Food Safety Inspection Service protocol. A total of 378 isolates (268 from our previous study) were serotyped and tested for antimicrobial susceptibility. The overall Salmonella count (mean log most probable number per carcass ± 95% confidence interval) and prevalence were 2.1 (2.0 to 2.3) and 37%, respectively. There were significant differences (P < 0.05) by Salmonella levels (i.e., counts and prevalence) by storage temperature (i.e., frozen, chilled, or ambient), retail store type (wet markets, supermarkets, and independent markets), and poultry company (chicken produced by integrated or nonintegrated company). Frozen chicken had the lowest Salmonella levels compared with chicken stored at other temperatures, chickens from wet markets had higher levels than those from other retail store types, and chicken produced by integrated companies had lower levels than nonintegrated companies. Thirty-one Salmonella serovars were identified among 378 isolates, with Salmonella Paratyphi B tartrate-positive (i.e., Salmonella Paratyphi B dT+) the most prevalent (44.7%), followed by Heidelberg (19%), Enteritidis (17.7%), Typhimurium (5.3%), and Anatum (2.1%). Of all the Salmonella isolates, 35.2% were resistant to 1 to 5 antimicrobial agents, 24.6% to 6 to 10, and 33.9% to 11 to 15. Among all the serovars obtained, Salmonella Paratyphi B dT+ and Salmonella Heidelberg were the most antimicrobial resistant. Salmonella prevalence was determined to be high, whereas cell numbers were relatively low. These data can be used in developing risk assessment models for preventing the transmission of Salmonella from chicken to humans in Colombia.