Influencing factors of positive rate of bronchoalveolar lavage fluid in patients with pneumonia: a multicenter retrospective study

Abstract

Objective To explore bronchoalveolar lavage fluid (BALF) positive rate in the etiological diagnosis of community-acquired pneumonia (CAP), healthcare associated pneumonia (HCAP) and immunocompromised hosts (ICH) in the real world of China, and to investigate influencing factors of the positive rate. Methods A retrospective study of 13 hospitals in 2014 hospitalized with pulmonary infection, all patients with community acquired pneumonia (CAP), HCAP or immunocompromised host pulmonary infection, and BALF examination was adopted within 1 weeks after admitted.The general data were collected including age, gender, underlying diseases, symptoms, the use of antibiotics, the severity of the disease, imaging manifestations, hospital mortality, length of stay in ICU, with the results of sputum culture were collected, and bronchoalveolar lavage (BAL) inspection time, BALF bacterial culture, fungal culture, nucleic acids of respiratory viruses, atypical pathogens (mycoplasma, chlamydia), Legionella and Pneumocystis jiroveci. Results 6 056 cases of pneumonia were collected, including 4 869 cases of CAP, 848 cases of HCAP, 338 cases of ICH pneumonia, 616 cases (10.2%) underwent BALF examination 1 week within admitting, 50 cases had severe pneumonia, 95% had used antibacterial drugs before BALF examination; 95% BALF were performed during antimicrobial treatment of the patient.The mean duration from the onset of the symptoms to the performance of BAL was 14(10, 24) d and the mean duration of the hospitalization before BAL was 4(2, 6) d. Untreated patients exhibited positive quantitative bacterial cultures (30.4%), as compared to patients with prior antimicrobial therapy having positive cultures (14.8%, P=0.041). The bacterial and fungal culture positive rates in severe patients were higher than the non-severe patients with CAP, HCAP (P<0.05). The positive rate of BALF bacterial and fungal culture was 32.3% in immunocompromised host (ICH), it was higher than that of HCAP patients (17.1%) and CAP patients (13.8%) (P<0.05).31 cases (37.8%) had adjust antibiotics according to the results of culture and drug sensitivity in 82 cases of pneumonia which pathogen was bacteria; All 17 cases targeted anti-infection drugs in the pneumonia which pathogen etiology were fungal or viral. Conclusions Immunocompromised host and severe pneumonia patients have positive rate of BALF pathogen.Identification of pathogens can guide the treatment of anti-infective drugs. Key words: Pneumonia; Bronchoalveolar lavage fluid; Etiology