Rapid antibiotic sensitivity testing and trimethoprim-mediated filamentation of clinical isolates of the Enterobacteriaceae assayed on a novel porous culture support.

A porous inorganic material (Anopore) was employed as a microbial culture and microcolony imaging support. Rapid Anopore-based antibiotic sensitivity testing (AST) methods were developed to assess the growth of clinical isolates, with the primary focus on testing the response of the Enterobacteriaceae to trimethoprim, but with the method supporting a wider applicability in terms of strains and antibiotics. It was possible to detect the growth of Enterobacter aerogenes after 25 min culture and to distinguish a trimethoprim-sensitive from a trimethoprim-resistant strain with 40 min incubation. MIC(90) determinations were made on Anopore; these were in good agreement with the results from the Vitek 2 and E-test methods. The Anopore method correctly identified sensitive (40/40) and resistant (17/17) strains of the Enterobacteriaceae and other Gram-negative rods within only 2-3 h culture. Additionally, a trimethoprim-resistant subpopulation (10 % of population) could be detected by microcolony formation within 2 h, and a smaller subpopulation (1 %) after 3.5 h. These results suggest that this is a viable approach for the rapid AST of purified strains, and that it may be able to deal with mixed populations. The microscopic examination of microcolonies during AST is an advantage of this method which revealed additional information. Filamentation triggered by trimethoprim was discovered in many species of the Enterobacteriaceae for which this phenomenon has not previously been reported. Filamentation was characterized by heterogeneity in terms of cell length, and also uneven nucleic acid distribution and flattening of damaged cells. The development and application of Anopore-based AST within clinical diagnostics is discussed.

Growth and multiplexed analysis of microorganisms on a subdivided, highly porous, inorganic chip manufactured from anopore.

A highly porous inorganic material (Anopore) was shown to be an effective support for culturing and imaging a wide range of microorganisms. An inert barrier grid was printed on the rigid surface of Anopore to create a "living chip" of 336 miniaturized compartments (200/cm2) with broad applications in microbial culture.