Transcriptional profiling analysis of the global regulator NorG, a GntR-like protein of Staphylococcus aureus.

The GntR-like protein NorG has been shown to affect Staphylococcus aureus genes involved in resistance to quinolones and ß-lactams, such as those encoding the NorB and AbcA transporters. To identify the target genes regulated by NorG, we carried out transcriptional-profiling assays using S. aureus RN6390 and its isogenic norG::cat mutant. Our data showed that NorG positively affected the transcription of global regulators mgrA, arlS, and sarZ. The three putative drug efflux pump genes most positively affected by NorG were the NorB efflux pump (5.1-fold), the MmpL-like protein SACOL2566 (5.2-fold), and the BcrA-like drug transporter SACOL2525 (5.7-fold) genes. The S. aureus predicted MmpL protein showed 53% homology with the MmpL lipid transporter of Mycobacterium tuberculosis, and the putative SACOL2525 protein showed 87% homology with the bacitracin drug transporter BcrA of Staphylococcus hominis. Two pump genes most negatively affected by NorG were the NorC (4-fold) and AbcA (6-fold) genes. Other categories of genes, such as those participating in amino acid, inorganic ion, or nucleotide transporters and metabolism, were also affected by NorG. Real-time reverse transcription (RT)-PCR assays for mgrA, arlS, sarZ, norB, norC, abcA, mmpL, and bcrA-like were carried out to verify microarray data and showed the same level of up- or downregulation by NorG. The norG mutant showed a 2-fold increase in resistance to norfloxacin and rhodamine, both substrates of the NorC transporter, which is consistent with the resistance phenotype conferred by overexpression of norC on a plasmid. These data indicate that NorG has broad regulatory function in S. aureus.

Perforations in surgeons' gloves.

The frequency of unused surgeons' gloves with perforations was investigated by using a watertightness test. Lot-to-lot variations and inter-lot variation were found. It is the responsibility of the manufacturer to ensure that the quality of the lot is in accordance with the stated Acceptable Quality Level.

Toxicity testing of medical device materials tested in human tissue cultures.

Rubber and plastic parts of medical devices were applied to human cell monolayers either directly or as aqueous extracts made at different time/temperature conditions. Thirteen rubber and twelve plastic samples were tested. The cultures were observed and photographed by use of a microscope with a camera before and after treatment with the test materials. The toxicity of the specimens was evaluated by comparison of the photographs. Alterations or disappearance of the cells or inhibited growth were interpreted as toxic effects of the materials. Twelve of the rubber and six of the plastic samples were evaluated as toxic in one or more of the systems.