Collect, boil and amplify--a simple approach for the detection of three common viruses associated with epidemic keratoconjunctivitis, conjunctivitis and dendritic ulcers.

During 2011' an outbreak of epidemic keratoconjunctivitis led to increased clinical requests for molecular screening of viruses from conjunctival swabs. To maximise throughput with minimal cost, a simple boil extraction on dry swabs followed by amplification and real-time detection using 'in-house' assays for herpes simplex viruses (HSV) and adenoviruses with RNaseP as an internal control was validated and introduced. Data from 541 patients who were tested for one or more viral targets was analysed. Adenovirus was most frequently detected accounting for 30% of all cases including the community outbreak. Genotyping of the hexon gene identified the cause as an adenovirus type 8. HSV was detected in 7% of the samples tested, predominantly HSV-1 with a single case of HSV-2. Invalid results due to poor RNaseP signals were reported in 10.5% of samples but for the HSV-1 assay 23% of the samples were invalid due to interference of the fluorescein dye used by ophthalmologists resulting in repeat sampling to obtain a valid result. Despite this, when compared to conventional techniques such as direct immunofluorescence, collect, boil and amplify increased significantly the detection of DNA viruses in conjunctival samples ensuring improved diagnosis, patient management and infection control measures at a modest cost.

Characterization of a novel macrolide efflux gene, mef(B), found linked to sul3 in porcine Escherichia coli.

OBJECTIVES: The aim of this study was to characterize a putative novel macrolide efflux gene located in the vicinity of sul3 in porcine Escherichia coli. METHODS: Five sul3-encoding E. coli isolates of porcine origin were investigated by plasmid characterization and random amplification of polymorphic DNA (RAPD) PCR. Unknown DNA adjacent to the sul3 genes was amplified using a PCR approach, followed by sequencing of the fragments. The putative macrolide efflux gene was cloned into pK18. The cloned gene was characterized by susceptibility testing by Etest in the presence and absence of efflux inhibitors. RESULTS: Five sul3-encoding isolates, demonstrated to be unrelated by RAPD PCR, were characterized. The immediate genetic context of sul3 in five isolates was identical to that in plasmid pVP440, and in all cases, sul3 was associated with class 1 integrons. In three isolates, an open reading frame (orf2) encoding a putative protein with 38% amino acid identity to Mef(A) was found, while the two remaining isolates contained a fragment of orf2 truncated by IS26 insertion. In three of the isolates, this DNA region was demonstrated to be located on non-conjugative plasmids. When the complete orf2 was cloned, it conferred high-level resistance to erythromycin and azithromycin, and the resistance property could be partially inhibited using the efflux inhibitor Phe-Arg beta-naphthylamide dihydrochloride. The gene was named mef(B). CONCLUSIONS: A new macrolide efflux protein, Mef(B), with 38% amino acid identity to Mef(A), has been characterized and represents the second member of the mef family of genes.