The most accurate test requiring IVD removal was quantitative catheter segment culture (segment of catheter is flushed or sonicated and plated, positive if ≥1000 CFU), with sensitivity of 0.83 (95% CI: 0.78–0.88) and specificity of 0.87 (95% CI: 0.85–0.89), followed by semi-quantitative catheter segment culture (5cm segment plated, positive if ≥ 15 CFU) with sensitivity of 0.82 (95% CI: 0.81–0.89) and specificity of 0.82 (95% CI: 0.80–0.84). The least accurate was qualitative catheter segment culture (positive if any growth) with a sensitivity of 0.90 (95% CI: 0.83–0.97) and specificity of 0.72 (95% CI: 0.66–0.78).
The limitations of this study include heterogeneity of study design, including limited data on the use of antibiotics before culture data was obtained and the baseline prevalence of bacteremia in the study populations. In addition, all data was obtained prior to the widespread use of antibiotic-coated catheters. While these results support the catheter-tip quantitative culture techniques that are already widely in use, they are less applicable to blood culture testing techniques, because quantitative assays are rarely used. Fortunately, all of these assays have a high negative predictive value, and false-positive results can be minimized by reserving testing for patients in whom there is moderate-to-high pretest probability of IVD related bloodstream infection.
7. Sopena N, Sabria M, Neunos 2000 Study Group. Multicenter study of hospital-acquired pneumonia in non-ICU patients. Chest. 2005;127:213-9.
A growing body of literature exists on hospital-acquired pneumonia (HAP) in the ICU setting. Sopena and colleagues extend the HAP literature to the non-ICU setting in a multicenter cross-sectional study. Cases of HAP were identified if clinical or radiographic evidence of pneumonia developed 72 hours after admission or within 10 days of a previous discharge. Patients who developed pneumonia in the ICU were excluded from analysis.
During an 18-month study period, 165 cases were identified with complete clinical and microbiologic data. The incidence of HAP was 3.1 ± 1.4 per 1000 hospital admissions. Ninety-eight (59.4%) patients diagnosed with HAP had severe underlying diseases that were classified as fatal (<1 year) or ultimately fatal (in 5 years). Extrinsic risk factors observed in patients with HAP included concurrent steroid use (29%), antibiotic therapy (53.3%), use of H2 blockers (37%), and hospitalization greater than 5 days (76%). Microbiologic data were positive in 60 (36.4%) cases. Streptococcus pneumoniae was diagnosed in 16 cases (9.7%), enterobacteriaceae in 8 (4.8%), Legionella pneumophila in 7 (4.2%), Aspergillus sp in 7 (4.2%), Pseudomonas aeruginosa in 7 (4.2%). Four cases of Staphylococcus aureus were diagnosed (3%), only one of which was methicillin resistant.
Complications of HAP occurred in 52.1% of cases and included respiratory failure (34.5%), pleural effusion (20.6%), septic shock (9.6%), renal failure (4.8%), and empyema (2.4%). Forty-three (26%) patients died during the hospitalization; 23 of these cases were directly attributed to HAP.
A limitation of the study is that the incidence of HAP was somewhat lower than reported in the literature and thus might represent an unintended sampling bias. Moreover, the study demonstrated underlying factors seen in patients with HAP, but these are not necessarily causative. Results useful to hospitalists include a higher than expected rate of Legionella and Aspergillus sp causing HAP in this population. A Legionella outbreak was not the explanation, as these cases were diagnosed in 5 different hospitals. The high frequency of adverse outcomes associated with HAP should alert hospitalists to the risk of nosocomial pneumonia in the non-ICU setting.