to the Editor
us of the ever-present threat posed by Finkelstein et al.’ remind Pseudomonas aeruginosa in hospitalized patients, with an interesting report of endocarditis, one of the rare complications of infection due to this organism. However, I think two of the statements in their final paragraph need clarifying. They state that valve replacement was required because of severe valve damage, not for control of infection, and that the finding of sterile vegetations suggests that medical treatment alone may occasionally be curative. In my experience valve replacement in endocarditis is quite commonly required, usually for haemodynamic reasons, and the removed valves are almost always bacteriologically sterile. The difficulty is often to persuade clinical colleagues that surgery is required, rather than altering doses or choices of antibiotics. Antibiotics are highly effective in sterilizing vegetations, unless these have progressed to abscess formation. They are completely ineffective in repairing structural damage to the valves. M. Sheppard
Department of Microbiology, Mayday University Hospital, Thornton Heath, Surrey CR7 7YE References
1. Finkelstein endocarditis.
R, Boulus M, Markievitcz M. Hospital-acquired J Hasp Infect 1991; 18: 161-163.
The conclusions drawn from the results of the recent paper of Humphreys et al. in the Journal (17: 117-123), are not substantiated by the authors’ data. No mention is made of the number of visitors to the theatre compared Ol95-6701/91~120283+14
to the Editor
with the number of full-time regular staff. The assumption was made that the shoes of the regular staff would make no contribution to bacterial floor counts. No mention is made as to when staff footwear was cleaned in relation to when the floors were cleaned; this footwear must be cleaned at the same time or else cross-contamination from footwear to floors, or vice versa, will occur. It must be assumed that the regular staff would change into theatre shoes at the notational line where the overshoes are donned by the visitors. The fact that the floor counts were the same on either side of the notational line only indicates that the floor is equally contaminated on either side. This suggests that the change to theatre shoes or plastic overshoes is ineffective in keeping the floors inside the theatre any cleaner than outside the theatre. The floor counts at the first time of sampling, 7-8 a.m., were at their highest suggesting that the floors were either not effectively cleaned at midnight or became contaminated quickly in the morning. At what time in the morning were the theatres first occupied? There was no indication of the counts before operating began. How effective is the cleaning in reducing the floor bacterial counts? It was interesting to see that Clostridium perfringens was not isolated. As this organism is often found in soil, both as a sporing and a vegetative organism, it is a good indicator of soil presence. The organism will only survive in a spore form on the floor. Its absence suggests that the theatre floors were not being contaminated with soil. Consequently, the theatre must be either not on the ground floor, the soil must be dropped from the shoes of staff going to the theatre before they get there, or the overshoes are effective. I suspect the former, as no C. perfringens were found on the floor before the notational change area. The sampling procedure was limited and yet the counts were high for clean theatre floors. The figures given were difficult to interpret, being stated as ‘total theatre floor bacterial colony counts’. I assumed the counts were total bacterial counts per plate. It was not surprising that the presence of Staphylococcus aureus was not influenced by the wearing or non-wearing of overshoes. The source of S. aureus will most likely be people in the theatre, not the floor, and its presence on the floor will be by deposition from above the floor. The comparison between the lack of need for overshoes in theatre and the lack of need for them in the Intensive Care Unit (ICU) is inappropriate, as operations are not performed in ICU and the degree of cleanliness is not as paramount. The figures quoted in the article really only support a title of ‘Theatre overshoes worn by theatre visitors do not cause any detectable change in theatre floor counts’. A. Perceval
Department, and Infectious Disease Unit, Alfred Hospital, Prahran, Victoria 3181, Australia