Mechanisms of antibiotic resistance in Escherichia coli isolates obtained from healthy children in Spain.

Antibiotic resistance and mechanisms involved were studied in Escherichia coli isolates from fecal samples of healthy children. Fifty fecal samples were analyzed, and one colony per sample was recovered and identified by biochemical and molecular tests. Forty-one E. coli isolates were obtained (82%). MIC testing was performed by agar dilution with 18 antibiotics, and the mechanisms of resistance were analyzed. Ampicillin resistance was detected in 24 isolates (58.5%), and bla TEM, bla SHV, and bla OXA type genes were studied by PCR and sequencing. The following -lactamases were detected (number of isolates): TEM (20), SHV-1 (1), and OXA-30 (1). The number of aminoglycoside-resistant isolates detected was as follows: streptomycin (15), tobramycin (1), gentamicin (1), and kanamycin (4). The aac(3)-IV gene was detected in the only gentamicin-resistant isolate. Nine (22%) and 2 (5%) isolates showed nalidixic acid (NAL R) and ciprofloxacin resistance (CIP R), respectively. Mutations in GyrA and ParC proteins were shown in both NAL R-CIP R isolates and were the following: (1) GyrA (S83L + D87N), ParC (S80I); and (2) GyrA (S83L + A84P), ParC (S80I + A108V). A single mutation in the S83 codon of the gyrA gene was found in the remaining seven NAL R-CIP s isolates. Tetracycline resistance was identified in 21 isolates (51%) and the following resistance genes were found (number of isolates): tetA (12), tetB (5), and tetD (1). Chloramphenicol resistance was detected in five isolates (12%). These results show that the intestinal tract of healthy children constitutes a reservoir of resistant bacteria and resistance genes

Mechanisms of resistance to expanded-spectrum beta-lactamases in Escherichia coli isolates recovered in a Spanish hospital.

Objectives: To characterize the -lactamase genes of the expanded-spectrum cephalosporin-resistant Escherichia coli isolates recovered in a Spanish hospital during the March 2002-March 2003 period. Methods: Thirty-four of the 1700 E. coli isolates recovered from unrela ted patients in a Spanish hospital showed expanded-spectrum cephalosporin resistance. The presence of genes encoding TEM, SHV, CTX-M, CMY-2-type or FOX -lactamases as well as the existence of mutations in the regulatory region of the chromosomal ampC gene were studied by PCR and sequencing in these 34 E. coli isolates. Results: The following extended-spectrum -lactamases (ESBLs) or plasmidic class C -lactamase genes were detected (number of isolates): bla CTX-M-14 (14), bla CTX-M-9 (4), bla CTX-M-32 (1), bla TEM-52 (2), bla SHV-12 (3) and bla CMY-2 (2). The remaining eight isolates showed a mutation in the promoter/attenuator region of the ampC chromosomal gene at position -42, in combination with mutations at positions -18, -1 and +58. The bla TEM-1 gene was also detected in 12 of the ESBL-producing isolates, in both CMY-2-producing isolates and in four of the eight isolates that showed a mutation at position -42 of the ampC promoter. Other mutations in the promoter/attenuator region were detected in association with ESBL or CMY-2 genes, such as the combination -18, -1 and +58, -28 and +58, or +22, +26, +27 and +32. No clonal relationship was found among the CTX-M-producing E. coli isolates by PFGE with Xba I enzyme. Conclusions: Approximately 1.5 % of the E. coli isolates of our hospital harboured ESBL genes, those of the CTX-M-9 group being the most common ones. © The Author 2005. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved

A Comprehensive Bibliometric Analysis of School-Based Physical Activity Research

Physical activity has captured considerable interest from international academic scholars due to its fundamental role in maintaining optimal health. Thus, this study sought to examine the scholarly articles on school-based physical activity, employing a comprehensive bibliometric analysis extracted from the Scopus database spanning 2013 to 2023. A filtering protocol was utilized to guide the selection of articles, and analyses were facilitated solely by Python programming. This research yielded extensive insights encompassing document type, publication rates, citation rates, prevalent keywords, and geographic distribution. The results revealed the prominence of "Articles" as the primary document category. Notably, the year 2020 was observed as the highest publication count, with 2014 being the peak year for citation rates. However, both publication and citation patterns exhibited substantial fluctuations. These analyses collectively identify the United States as the largest contributor among the top ten countries, accompanied by substantial contributions from European nations. The analysis of the top 50 most-cited journal articles indicates a prevalence of articles authored by one to five individuals, with a peak in publications during 2014, followed by a gradual decline. Notably, the keyword "children" prominently emerges across the datasets, underscoring its frequent utilization in the context of school-based physical activity research

Genotypic-Phenotypic Discrepancies between Antibiotic Resistance Characteristics of Escherichia coli Isolates from Calves in Management Settings with High and Low Antibiotic Use ▿ †

We hypothesized that bacterial populations growing in the absence of antibiotics will accumulate more resistance gene mutations than bacterial populations growing in the presence of antibiotics. If this is so, the prevalence of dysfunctional resistance genes (resistance pseudogenes) could provide a measure of the level of antibiotic exposure present in a given environment. As a proof-of-concept test, we assayed field strains of Escherichia coli for their resistance genotypes using a resistance gene microarray and further characterized isolates that had resistance phenotype-genotype discrepancies. We found a small but significant association between the prevalence of isolates with resistance pseudogenes and the lower antibiotic use environment of a beef cow-calf operation versus a higher antibiotic use dairy calf ranch (Fisher's exact test, P = 0.044). Other significant findings include a very strong association between the dairy calf ranch isolates and phenotypes unexplained by well-known resistance genes (Fisher's exact test, P < 0.0001). Two novel resistance genes were discovered in E. coli isolates from the dairy calf ranch, one associated with resistance to aminoglycosides and one associated with resistance to trimethoprim. In addition, isolates resistant to expanded-spectrum cephalosporins but negative for blaCMY-2 had mutations in the promoter regions of the chromosomal E. coli ampC gene consistent with reported overexpression of native AmpC beta-lactamase. Similar mutations in hospital E. coli isolates have been reported worldwide. Prevalence or rates of E. coli ampC promoter mutations may be used as a marker for high expanded-spectrum cephalosporin use environments