Comparison study between sensitivity of different staining methods and immunofluorescent staining and PCR of three induced sputum exam and bal for diagnosis of pneumocystis pneumonia in aids
Abstract:
Background. PCP remains an important cause of morbidity and mortality in AIDS. Bronchoscopy with BAL is gold standard procedure for PCP diagnosis. Sputum induction has been proposed as noninvasive procedure but less sensitivity than BAL. A variety of staining methods and PCR have been used to detect P. carinii. Multiple induced sputa could increase diagnostic yield and may be comparable to BAL fluid. Objectives. 1. To compare the sensitivity of cytochemical stains with immunofluorescent stain and PCR in detecting P. carinii. 2. To compare the sensitivity of PCP detection using one induced sputum and three induced sputa. 3. To compare the sensitivity of PCP detection using BAL fluid and three induced sputa. Design. Descriptive study Methods. A prospective study was conducted in thirty five patients with HIV infection who suspected PCP at King Chulalongkorn Memorial hospital from March to November, 2006 PCP was diagnosed by finding organism plus symptoms, chest radiography consistent with PCP and clinical response to standard treatment. Three times of sputum induction and then bronchoscopy were performed in each patients to collect sputa and BAL fluid. The specimens were stained with Giemsa, GMS, Toluidine blue O, IFA and PCR to identify the causative organism. Results. PCR staining had highest sensitivity (88.6%) whereas Giemsa stain showed lowest sensitivity (22.9%). Higher diagnostic yields can be achieved by multiple sputa and multiple staining methods were used. Sensitivities of 4 different staining methods and PCR of BAL fluid were high and not different. When multiple sputa were stained at least 2 methods, sensitivities was increased and comparable outcome to BAL fluid. No serious adverse event was observed in sputum induction, confirming that this procedure was a very well-tolerated. One case developed respiratory failure during bronchoscopy. Additionally, sputum induction exerted lower costs. Conclusions. Compared with bronchoscopy, 3 induced sputa offered many advantages in terms of diagnostic yield, safety and cost. Sputum induction provides an alternative procedure to bronchoscopy with BAL in the diagnosis of PCP.