Microbial air monitoring in operating theatres: experience at the University Hospital of Parma.

BACKGROUND: Microbial air monitoring in operating theatres has been a subject of interest and debate. No generally accepted sampling methods and threshold values are available. AIM: To assess microbial air contamination in empty and working conventionally ventilated operating theatres over a three-year period at the University Hospital of Parma, Italy. METHODS: Air sampling was performed in 29 operating theatres. Both active and passive sampling methods were used to assess bacterial and fungal contamination. FINDINGS: In empty theatres, median bacterial values of 12 colony-forming units (cfu)/m(3) [interquartile range (IQR) 4-32] and 1 index of microbial air contamination (IMA) (IQR 0-3) were recorded. In working theatres, these values increased significantly (P < 0.001) to 80 cfu/m(3) (IQR 42-176) and 7 IMA (IQR 4-13). Maximum recorded values were 166 cfu/m(3) and 8 IMA for empty theatres, and 798 cfu/m(3) and 42 IMA for working theatres. Combining active and passive samplings, fungi were isolated in 39.13% of samples collected in empty theatres and 56.95% of samples collected in working theatres. Over the three-year study period, bacterial contamination decreased in both empty and working theatres, and the percentage of samples devoid of fungi increased. In working theatres, a significant correlation was found between the bacterial contamination values assessed using passive and active sampling methods (P < 0.001). CONCLUSION: Microbiological monitoring is a useful tool for assessment of the contamination of operating theatres in order to improve air quality.

Comparison of immunological reactivity to two major antigens of homologous and AD169 human cytomegalovirus strains during primary infection in renal transplant patients.

The IgG and IgM immunoblotting patterns for the major HCMV antigens p65 and p55/52 were studied in 5 renal transplant recipients during primary HCMV infections. Sequential sera from the 5 patients were tested in parallel with standardized antigens derived from the reference strain AD169 and from the patient'own isolates. The immunoblotting patterns differed from patient to patient as well as between strain AD169 and the patient's homologous isolates. The differences consisted in a better response to the antigens derived from the reference strain AD169, suggesting a delay of the IgM/IgG switch and of the affinity maturation of IgG antibodies to the homologous p65 and p55/52 antigens. The results suggest caution in the interpretation of immunoblotting data derived from laboratory strains such as AD169.