Electronic Nose in the Detection of Wound Infection Bacteria from Bacterial Cultures: A Proof-of-Principle Study.

BACKGROUND: Soft tissue infections, including postoperative wound infections, result in a significant burden for modern society. Rapid diagnosis of wound infections is based on bacterial stains, cultures, and polymerase chain reaction assays, and the results are available earliest after several hours, but more often not until days after. Therefore, antibiotic treatment is often administered empirically without a specific diagnosis. METHODS: We employed our electronic nose (eNose) system for this proof-of-concept study, aiming to differentiate the most relevant bacteria causing wound infections utilizing a set of clinical bacterial cultures on identical blood culture dishes, and established bacterial lines from the gaseous headspace. RESULTS: Our eNose system was capable of differentiating both methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pyogenes, Escherichia coli, Pseudomonas aeruginosa, and Clostridium perfringens with an accuracy of 78% within minutes without prior sample preparation. Most importantly, the system was capable of differentiating MRSA from MSSA with a sensitivity of 83%, a specificity of 100%, and an overall accuracy of 91%. CONCLUSIONS: Our results support the concept of rapid detection of the most relevant bacteria causing wound infections and ultimately differentiating MRSA from MSSA utilizing gaseous headspace sampling with an eNose.

The real contamination of femoral head allografts washed with pulse lavage.

At the Tampere Bone Bank, all the discarded femoral heads from September 1997 to May 2000 were recultured. The grafts had been washed with pulse lavage at harvesting. 48 grafts had been discarded because of a positive culture and 85 with negative cultures because of positive or insufficient serological information. The femoral heads were split into halves, which were recultured as a whole in thioglycolate broth for 14 days. The contamination of previously culture positive and negative femoral heads did not differ. In only 2 cases did we find the same type of bacteria in the primary as in the new culture. Most of the primary contamination proved to be false positive. The real contamination seems to be very low, at least after pulse lavage washing of the femoral head.