Nosocomial contamination of laryngoscope handles: challenging current guidelines.

BACKGROUND: Laryngoscope blades are often cleaned between cases according to well-defined protocols. However, despite evidence that laryngoscope handles could be a source of nosocomial infection, neither our institution nor the American Society of Anesthesiologists has any specific guidelines for handle disinfection. We hypothesized that laryngoscope handles may be sufficiently contaminated with bacteria and viruses to justify the implementation of new handle-cleaning protocols. METHODS: Sixty laryngoscope handles from the adult operating rooms were sampled with premoistened sterile swabs. Collection was performed between cases, in operating rooms hosting a broad variety of subspecialty procedures, after the room and equipment had been thoroughly cleaned for the subsequent case. Samples from 40 handles were sent for aerobic bacterial culture, and antimicrobial susceptibility testing was performed for significant isolates. Samples from 20 handles were examined for viral contamination using a polymerase chain reaction assay that detects 17 respiratory viruses. RESULTS: Of the 40 samples sent for culture, 30 (75%) were positive for bacterial contamination. Of these positive cultures, 25 (62.5%) yielded coagulase-negative staphylococci, seven (17.5%) Bacillusspp. not anthracis, three (7.5%) alpha-hemolytic Streptococcusspp., and one each (2.5%) of Enterococcusspp., Staphylococcus aureus(S. aureus), and Corynebacteriumspp. No vancomycin-resistant enterococci, methicillin-resistant S. aureus, or Gram-negative rods were detected. All viral tests were negative. CONCLUSION: We found a high incidence of bacterial contamination of laryngoscope handles despite low-level disinfection. However, no vancomycin-resistant enterococci, methicillin-resistant S. aureus, Gram-negative rods, or respiratory viruses were detected. Our results support adoption of guidelines that include, at a minimum, mandatory low-level disinfection of laryngoscope handles after each patient use.

Transcriptional profile of the Arabidopsis root quiescent center.

The self-renewal characteristics of stem cells render them vital engines of development. To better understand the molecular mechanisms that determine the properties of stem cells, transcript profiling was conducted on quiescent center (QC) cells from the Arabidopsis thaliana root meristem. The AGAMOUS-LIKE 42 (AGL42) gene, which encodes a MADS box transcription factor whose expression is enriched in the QC, was used to mark these cells. RNA was isolated from sorted cells, labeled, and hybridized to Affymetrix microarrays. Comparisons with digital in situ expression profiles of surrounding tissues identified a set of genes enriched in the QC. Promoter regions from a subset of transcription factors identified as enriched in the QC conferred expression in the QC. These studies demonstrated that it is possible to successfully isolate and profile a rare cell type in the plant. Mutations in all enriched transcription factor genes including AGL42 exhibited no detectable root phenotype, raising the possibility of a high degree of functional redundancy in the QC.