The ability of topical antiseptics to penetrate eschar of burn patients was determined by the agar diffusion technique. Gentamicin sulfate, mafenide acetate, nitrofurazone, povidone-iodine, silver nitrate, and silver sulfadiazine were tested against clinical isolates of Candida albicans, Staphylococcus, Streptococcus, and gram-negative bacilli including Pseudomonas aeruginosa. In practically all instances, the diameters of the zones of inhibition observed using eschar were comparable to those obtained with filter-paper discs. This finding showed that the antimicrobial agents could penetrate eschar and retain their effectiveness after penetration

Pseudomonas aeruginosa was isolated from tomatoes, radishes, celery, carrots, endive, cabbage, cucumbers, onions, and lettuce obtained from the kitchen of a general hospital, with tomatoes yielding both highest frequencies of isolation and highest counts. Presence of P. aeruginosa on the hands of kitchen personnel and cutting boards and knives which they used suggests acquisition of the organism through contact with these vegetables. It is estimated that a patient consuming an average portion of tomato salad might ingest as many as 5 103 colony-forming units of P. aeruginosa. Pyocine types of P. aeruginosa isolated from clinical specimens were frequently identical to those recovered from vegetables, thus implicating tomatoes and other vegetables as an important source and vehicle by which P. aeruginosa colonizes the intestinal tract of patients.

The transmission of Pseudomonas aeruginosa was studied in the burn unit and the intensive care unit of a 650-bed hospital. There was a tendency among patients in the burn unit to yield more than one type of P. aeruginosa, and several patients shared the same types at a particular point in time, suggesting cross-contamination among patients. Similar observations were made in the intensive care unit. Cultures from the hands of nurses caring for these patients yielded the same types of P. aeruginosa, suggesting the direct handling of patients by the nursing personnel to be the principal mode of transmission.