Diagnosis of nosocomial pneumonia in medical ward:: repeatability of the protected specimen brush

The aims of this study were to assess the repeatability of two pairs of protected specimen brushes (PSB) done successively in the same lung area and either processed at the bedside or in the laboratory, and to provide a description of the bacteriological findings in 39 cases of suspected nosocomial pneumonia occurring in nonventilated patients. Four PSB were divided into two pairs. One pair of brushes (PB) was prepared at bedside and then sent to the laboratory; the other pair (PL) was immediately sent to the laboratory for complete processing. According to a 10(3) colony forming units (cfu).mL(-1) threshold, 49%, out of 156 PSB were positive. Using the 10(-3) cfu.mL threshold, the PL brushes were 89.7% concordant while the PB brushes were 76.9% concordant. The repeatability as expressed by K-value of the cultures of PSB was higher for PL brushes than for PB brushes (K-values of 0.795 and 0.537 respectively, p = 0.12). Bacterial species were isolated in 58.3% of 156 PSB (176 isolates). In 14 cases, cultures of PSB disclosed more than one micro-organism in a concentration > 10(3) cfu.mL(-1). The most frequently isolated organisms were Pseudomonas spp. (23.9%), Enterobacteriaceae (23.3%,), Streptococcus spp. (21.6%,) and Staphylococcus spp. (13.1%). Polymicrobial cultures were more frequent if the patient had a tracheostomy (seven out of the nine patients with a tracheostomy versus seven out of the 30 patients without a tracheostomy, p < 0.01). Bacteriological discrepancies leading to a potential troublesome choice in antibiotherapy were observed in 31.8% of the patients for PL brushes and 56.5%, of the patients for PB brushes. There is a low degree of repeatability of protected specimen brushes outside intensive care units which seem dependent on sampling processing. The distribution of pathogens found in case of suspicion of nosocomial pneumonia in nonventilated patients appears to be similar to that obtained in ventilator-associated pneumonia.