Department of International Development (UKAID) through Communicable Diseases Health Service Delivery.

BackgroundInappropriate antibiotic prescribing causes widespread serious health problems. To reduce prescribing of antibiotics in Chinese primary care to children with upper respiratory tract infections (URTIs), we developed an intervention comprising clinical guidelines, monthly prescribing review meetings, doctor–patient communication skills training, and education materials for caregivers. We previously evaluated our intervention using an unblinded cluster-randomised controlled trial (cRCT) in 25 primary care facilities across two rural counties. When our trial ended at the 6-month follow-up period, we found that the intervention had reduced antibiotic prescribing for childhood URTIs by 29 percentage points (pp) (95% CI −42 to −16).Methods and findingsIn this long-term follow-up study, we collected our trial outcomes from the one county (14 facilities and 1:1 cluster randomisation ratio) that had electronic records available 12 months after the trial ended, at the 18-month follow-up period. Our primary outcome was the antibiotic prescription rate (APR)—the percentage of outpatient prescriptions containing any antibiotic(s) for children aged 2 to 14 years who had a primary diagnosis of a URTI and had no other illness requiring antibiotics. We also conducted 15 in-depth interviews to understand how interventions were sustained.In intervention facilities, the APR was 84% (1,171 out of 1,400) at baseline, 37% (515 out of 1,380) at 6 months, and 54% (2,748 out of 5,084) at 18 months, and in control facilities, it was 76% (1,063 out of 1,400), 77% (1,084 out of 1,400), and 75% (2,772 out of 3,685), respectively. After adjusting for patient and prescribing doctor covariates, compared to the baseline intervention-control difference, the difference at 6 months represented a 6-month intervention-arm reduction in the APR of −49 pp (95% CI −63 to −35; P < 0.0001), and compared to the baseline difference, the difference at 18 months represented an 18-month intervention-arm reduction in the APR of −36 pp (95% CI −55 to −17; P < 0.0001). Compared to the 6-month intervention-control difference, the difference at 18 months represented no change in the APR: 13 pp (95% CI −7 to 33; P = 0.21). Factors reported to sustain reductions in antibiotic prescribing included doctors’ improved knowledge and communication skills and focused prescription review meetings, whereas lack of supervision and monitoring may be associated with relapse. Key limitations were not including all clusters from the trial and not collecting returned visits or sepsis cases.ConclusionsOur intervention was associated with sustained and substantial reductions in antibiotic prescribing at the end of the intervention period and 12 months later. Our intervention may be adapted to similar resource-poor settings.Trial registrationISRCTN registry ISRCTN14340536.

Full-length RecE and RecT from Rac prophage mediate highly efficient linear-linear homologous recombination that can be used to clone large DNA regions directly from genomic DNA into expression vectors, bypassing library construction and screening. Homologous recombination mediated by Redαβ from lambda phage has been widely used for recombinant DNA engineering. Here we present a protocol for direct cloning and engineering of biosynthetic gene clusters, large operons or single genes from genomic DNA using one Escherichia coli host that harbors both RecET and Redαβ systems. The pipeline uses standardized cassettes for horizontal gene transfer options, as well as vectors with different replication origins configured to minimize recombineering background through the use of selectively replicating templates or CcdB counterselection. These optimized reagents and protocols facilitate fast acquisition of transgenes from genomic DNA preparations, which are ready for heterologous expression within 1 week.

The exponentially increasing volumes of DNA sequence data highlight the need for new DNA cloning methods to explore the new information. Here, we describe ‘ExoCET’ (Exonuclease Combined with RecET recombination) to directly clone any chosen region from bacterial and mammalian genomes with nucleotide precision into operational plasmids. ExoCET combines in vitro exonuclease and annealing with the remarkable capacity of full length RecET homologous recombination (HR) to retrieve specified regions from genomic DNA preparations. Using T4 polymerase (T4pol) as the in vitro exonuclease for ExoCET, we directly cloned large regions (>50 kb) from bacterial and mammalian genomes, including DNA isolated from blood. Employing RecET HR or Cas9 cleavage in vitro, the directly cloned region can be chosen with nucleotide precision to position, for example, a gene into an expression vector without the need for further subcloning. In addition to its utility for bioprospecting in bacterial genomes, ExoCET presents straightforward access to mammalian genomes for various applications such as region-specific DNA sequencing that retains haplotype phasing, the rapid construction of optimal, haplotypic, isogenic targeting constructs or a new way to genotype that presents advantages over Southern blotting or polymerase chain reaction. The direct cloning capacities of ExoCET present new freedoms in recombinant DNA technology.

The kidney is a vital organ for the elimination of therapeutic drugs and their metabolites. Renal drug transporters, which are primarily located in the renal proximal tubules, play an important role in tubular secretion and reabsorption of drug molecules in the kidney. Tubular secretion is characterized by high clearance capacities, broad substrate specificities, and distinct charge selectivity for organic cations and anions. In the past two decades, substantial progress has been made in understanding the roles of transporters in drug disposition, efficacy, toxicity and drug–drug interactions (DDIs). In the kidney, several transporters are involved in renal handling of organic cation (OC) and organic anion (OA) drugs. These transporters are increasingly recognized as the target for clinically significant DDIs. This review focuses on the functional characteristics of major human renal drug transporters and their involvement in clinically significant DDIs.

Atenolol is a b-blocker widely used in the treatment of hypertension. Atenolol is cleared predominantly by the kidney by both glomerular filtration and active secretion, but the molecular mechanisms involved in its renal secretion are unclear. Using a panel of human embryonic kidney cell lines stably expressing human organic cation transporter (hOCT) 1-3, human organic anion transporter (hOAT) 1, hOAT3, human multidrug and toxin extrusion protein (hMATE) 1, and hMATE2-K, we found that atenolol interacted with both organic cation and anion transporters. However, it is transported by hOCT1, hOCT2, hMATE1, and hMATE2-K, but not by hOCT3, hOAT1, and hOAT3. A detailed kinetic analysis coupled with absolute quantification of membrane transporter proteins by liquid chromatographytandem mass spectrometry revealed that atenolol is an excellent substrate for the renal transporters hOCT2, hMATE1, and hMATE2-K. The K m values for hOCT2, hMATE1, and hMATE2-K are 280 6 4, 32 6 5, and 76 6 14 mM, respectively, and the calculated turnover numbers are 2.76, 0.41, and 2.20 s 21 , respectively. To demonstrate unidirectional transepithelial transport of atenolol, we developed and functionally validated a hOCT2/hMATE1 double-transfected Madin-Darby canine kidney cell culture model. Transwell studies showed that atenolol transport in the basal (B)-to-apical (A) direction is 27-fold higher than in the A-to-B direction, whereas its B-to-A/A-to-B transport ratio was only 2 in the vectortransfected control cells. The overall permeability of atenolol in the B-to-A direction in hOCT2/hMATE1 cells was 44-fold higher than in control cells. Together, our data support that atenolol tubular secretion is mediated through the hOCT2/hMATEs secretion pathway and suggest a significant role of organic cation transporters in the disposition of an important antihypertensive drug.

Background:The rapidly increasing dissemination of carbapenem-resistant Enterobacteriaceae (CRE) in both humans and animals poses a global threat to public health. However, the transmission of CRE between humans and animals has not yet been well studied.Objectives:We investigated the prevalence, risk factors, and drivers of CRE transmission between humans and their backyard animals in rural China.Methods:We conducted a comprehensive sampling strategy in 12 villages in Shandong, China. Using the household [residents and their backyard animals (farm and companion animals)] as a single surveillance unit, we assessed the prevalence of CRE at the household level and examined the factors associated with CRE carriage through a detailed questionnaire. Genetic relationships among human- and animal-derived CRE were assessed using whole-genome sequencing–based molecular methods.Results:A total of 88 New Delhi metallo-β-lactamases–type carbapenem-resistant Escherichia coli (NDM-EC), including 17 from humans, 44 from pigs, 12 from chickens, 1 from cattle, and 2 from dogs, were isolated from 65 of the 746 households examined. The remaining 12 NDM-EC were from flies in the immediate backyard environment. The NDM-EC colonization in households was significantly associated with a) the number of species of backyard animals raised/kept in the same household, and b) the use of human and/or animal feces as fertilizer. Discriminant analysis of principal components (DAPC) revealed that a large proportion of the core genomes of the NDM-EC belonged to strains from hosts other than their own, and several human isolates shared closely related core single-nucleotide polymorphisms and blaNDM genetic contexts with isolates from backyard animals.Conclusions:To our knowledge, we are the first to report evidence of direct transmission of NDM-EC between humans and animals. Given the rise of NDM-EC in community and hospital infections, combating NDM-EC transmission in backyard farm systems is needed. https://doi.org/10.1289/EHP5251

Precise and fluent genetic manipulation is still limited to only a few prokaryotes. Ideally the highly advanced technologies available in Escherichia coli could be broadly applied. Our efforts to apply lambda Red technology, widely termed ‘recombineering’, in Photorhabdus and Xenorhabdus yielded only limited success. Consequently we explored the properties of an endogenous Photorhabdus luminescens lambda Red-like operon, Plu2934/Plu2935/Plu2936. Bioinformatic and functional tests indicate that Plu2936 is a 5’-3’ exonuclease equivalent to Redα and Plu2935 is a single strand annealing protein equivalent to Redβ. Plu2934 dramatically enhanced recombineering efficiency. Results from bioinformatic analysis and recombineering assays suggest that Plu2934 may be functionally equivalent to Redγ, which inhibits the major endogenous E. coli nuclease, RecBCD. The recombineering utility of Plu2934/Plu2935/Plu2936 was demonstrated by engineering Photorhabdus and Xenorhabdus genomes, including the activation of the 49-kb non-ribosomal peptide synthase (NRPS) gene cluster plu2670 by insertion of a tetracycline inducible promoter. After tetracycline induction, novel secondary metabolites were identified. Our work unlocks the potential for bioprospecting and functional genomics in the Photorhabdus, Xenorhabdus and related genomes.