The American journal of the medical sciences
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Comparative Study
Comparison of tracheal aspirates and protected brush catheter specimens for identifying pathogenic bacteria in mechanically ventilated patients.
Bacterial respiratory infections are common in patients undergoing prolonged mechanical ventilation, and antibiotic selection often is based upon the results of smears and cultures of tracheal aspirates (TA). This study was designed to determine the reliability of gram stains, cultures and antibody-coating of bacteria in TA by comparing them with the results of quantitative cultures of specimens obtained by protected brush catheters (PBC) inserted into involved areas of lung parenchyma. Twenty-two patients on mechanical ventilation for at least 72 hours, with new radiographic infiltrates and fever, were studied. ⋯ Cultures of TA revealed potential pathogens in 20 patients, and in 15, multiple pathogens were present. The bacteria isolated from PBC also were present in 14 of the 16 patients with greater than or equal to 10(3) CFU in PBC cultures (88%). Antibody coating was present in TA from 12 patients, and antibody coating correlated poorly with cultures of PBC specimens.(ABSTRACT TRUNCATED AT 250 WORDS)