Determination of microbial volatile organic compounds adsorbed on house dust particles and gypsum board using SPME/GC-MS.

UNLABELLED: Adsorption of microbial volatile organic compounds (MVOCs) on house dust was analyzed by performing solid phase microextraction (SPME) in combination with gas chromatography-mass spectrometry (GC-MS). Settled dust samples were exposed to five selected MVOCs and to cultures of the molds Stachybotrus chartarum, Aspergillus versicolor, and Chaetomium globosum. Considerable desorption of the MVOCs adsorbed on the dust occurred spontaneously within a few hours at room temperature and within several days or weeks after storage at -20 degrees or -80 degrees C. Similar results were found for a sample of a gypsum board cultivated with A. versicolor. SPME/GC-MS analysis performed immediately after sampling revealed several of the studied MVOCs on gypsum board and settled dust collected in a house garage with visible mold growth. MVOCs adsorbed on respirable particles of house dust can be inhaled and reach deep into the respiratory system, which may partly explain health effects that have been found to be associated with the presence of low concentrations of MVOCs in air. Particle-bound MVOCs can easily be detected by SPME/GC-MS analysis, thus this technique may prove to be very useful in indoor air research for identifying factors that affect human health. PRACTICAL IMPLICATIONS: We used SPME combined with GC-MS to study the adsorption and desorption of MVOCs on house dust particles that had been exposed to cultivated molds and molds in a damp building. Adsorbed MVOCs desorb spontaneously but this process can be slowed down by storing samples at -20 degrees or -80 degrees C. This opens up a possibility to apply SPME/GC-MS to reveal mold growth in buildings and to determine MVOCs in respirable dust particles that may reach deep in the respiratory system and lead to respiratory illnesses.

External ventricular drainage catheters: effect of surface heparinization on bacterial colonization and infection.

Surface heparinization of central venous catheters has earlier been shown to reduce the frequency of bacterial colonization and septicaemia. The present study was undertaken to investigate the benefit of surface heparinization of external ventricular drainage (EVD) catheters in relation to bacterial colonization, as measured by bacterial growth and examination by a 16S-rRNA PCR assay, of catheters and of samples of cerebrospinal fluid (CSF). Ninety-eight heparinized and one hundred unheparinized EVD catheters from the same batch of catheters were used. Twenty point five percent of the heparinized and 22.8% (p = 0.63) of the unheparinized EVD catheters were colonized with bacteria. Culture of CSF, which is the definition of clinical infection in this study, yielded growth in 10.3% of patients with heparinized and in 6.3% (p = 0.18) of those with unheparinized catheters. PCR examination yielded positive signal in 31.3% of patients with heparinized catheters and in 37.7% (p = 0.061) of patients without (CSF and catheters). In the subgroup of patients with subarachnoid haemorrhages, there was a tendency, though not statistically significant, towards a lowered frequency of colonization with 23.1% for heparinized and 33.3% (p = 0.31) for unheparinized catheters. PCR examination did not contribute any further to the diagnostic procedure in the patients concerned. The EVD catheters are skin-penetrating devices and contamination from the skin flora is common. Skin cultures, obtained after skin disinfection and insertion of catheters, showed growth of bacteria in 62% of the patients.