Polluted wetlands contain multidrug-resistance plasmids encoding CTX-M-type extended-spectrum ß-lactamases.

While most detailed analyses of antibiotic resistance plasmids focus on those found in clinical isolates, less is known about the vast environmental reservoir of mobile genetic elements and the resistance and virulence factors they encode. We selectively isolated three strains of cefotaxime-resistant Escherichia coli from a wastewater-impacted coastal wetland. The cefotaxime-resistant phenotype was transmissible to a lab strain of E. coli after one hour, with frequencies as high as 10-3 transconjugants per recipient. Two of the plasmids also transferred cefotaxime resistance to Pseudomonas putida, but these were unable to back-transfer this resistance from P. putida to E. coli. In addition to the cephalosporins, E. coli transconjugants inherited resistance to at least seven distinct classes of antibiotics. Complete nucleotide sequences revealed large IncF-type plasmids with globally distributed replicon sequence types F31:A4:B1 and F18:B1:C4 carrying diverse antibiotic resistance and virulence genes. The plasmids encoded extended-spectrum ß-lactamases blaCTX-M-15 or blaCTX-M-55, each associated with the insertion sequence ISEc9, although in different local arrangements. Despite similar resistance profiles, the plasmids shared only one resistance gene in common, the aminoglycoside acetyltransferase aac(3)-IIe. Plasmid accessory cargo also included virulence factors involved in iron acquisition and defense against host immunity. Despite their sequence similarities, several large-scale recombination events were detected, including rearrangements and inversions. In conclusion, selection with a single antibiotic, cefotaxime, yielded conjugative plasmids conferring multiple resistance and virulence factors. Clearly, efforts to limit the spread of antibiotic resistance and virulence among bacteria must include a greater understanding of mobile elements in the natural and human-impacted environments.

Human Growth Hormone Delivery with a Microneedle Transdermal System: Preclinical Formulation, Stability, Delivery and PK of Therapeutically Relevant Doses.

This study evaluated the feasibility of coating formulated recombinant human growth hormone (rhGH) on a titanium microneedle transdermal delivery system, Zosano Pharma (ZP)-hGH, and assessed preclinical patch delivery performance. Formulation rheology and surface activity were assessed by viscometry and contact angle measurement. rhGH liquid formulation was coated onto titanium microneedles by dip-coating and drying. The stability of coated rhGH was determined by size exclusion chromatography-high performance liquid chromatography (SEC-HPLC). Preclinical delivery and pharmacokinetic studies were conducted in female hairless guinea pigs (HGP) using rhGH coated microneedle patches at 0.5 and 1 mg doses and compared to Norditropin® a commercially approved rhGH subcutaneous injection. Studies demonstrated successful rhGH formulation development and coating on microneedle arrays. The ZP-hGH patches remained stable at 40 °C for six months with no significant change in % aggregates. Pharmacokinetic studies showed that the rhGH-coated microneedle patches, delivered with high efficiency and the doses delivered indicated linearity with average Tmax of 30 min. The absolute bioavailability of the microneedle rhGH patches was similar to subcutaneous Norditropin® injections. These results suggest that ZP-transdermal microneedle patch delivery of rhGH is feasible and may offer an effective and patient-friendly alternative to currently marketed rhGH injectables.