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

Abstract

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 w10 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, pv0.01). 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.

Management of nosocomial pneumonia on a medical ward: a comparative study of outcomes and costs of invasive procedures

“…Major complications (pneumothorax or bronchial bleeding) occurred in 0.6% of cases [24]. These drawbacks probably explain the rarity of studies of invasive NP management outside the ICU [8].…”

“…The PSB sample was processed in the laboratory. Lung infection was distinguished from colonization by using a cut‐off of 10 3 CFU/mL [8]. In the NIM strategy, patients received empirical antibiotic treatment, the drug(s) and regimen being chosen by their attending physician.…”

“…PSB might help to improve patient management by definitively diagnosing pulmonary infection and by identifying the responsible pathogen [6]. Indeed, it was previously found that PSB led to improved diagnosis and treatment of NP in non‐ventilated patients [8]. An invasive NP management strategy may also lead to more appropriate antibiotic use and thereby reduce costs [7,9].…”

“…However, this requires specialized equipment and trained personnel, is expensive, and may in itself be harmful in some cases [10]. These drawbacks must be seen in the light of the better outcome of NP in non‐ICU patients than in ICU patients [5,6,8].…”

Nosocomial Pneumonia Outside the Intensive Care Unit

“…However, 1 study showed a low degree of repeatability of PBS in nonintubated patients, and suggested that PBS should be processed with as little manipulation as possible. 30 False positives are more frequent in patients with COPD or with purulent bronchitis and false negatives are more often observed in patients receiving antibiotic treatment in the previous 48 to 72 hours. Bronchoscopy with BAL or PSB outside the ICU are always indicated in immunosuppressed patients or those who do not improve after 48 to 72 hours of empiric antibiotic treatment.…”