Study Of The Sputum Samples Impact On The Detection Of Pathogens In Patients With Community-acquired Pneumonia

Objective: Community-acquired pneumonia (CAP) is a common disease inrespiratory system, and its morbidity and mortality remain high. The most importantpathogen is Streptococcus pneumoniae. At present the commonly used the method todetect respiratory infection detection in our country is sputum bacterial culture, but thepositive rate of this method has been low, making the diagnostic based on sputumbacterial culture highly controversial. Streptococcus pneumoniae urinary antigendetection, known as immunochromatographic test, is by immunechromatography test todo the determination of Streptococcus pneumoniae antigen lipopolysaccharide.Research shows that, Streptococcus pneumoniae urinary antigen detection cansignificantly improve the detection rate of Streptococcus pneumoniae. In this study,sputum samples of54CAP patients were analyzed by culture and ICT. ThenStreptococcus pneumoniae mixed with sputum samples from15patients with CAP andquantitative culture in blood agar. The purpose of the experiment was to explore thereasons of the lower positive rate of bacterial culture for Streptococcus pneumoniaefrom sputum samples of patients with community-acquired pneumonia and the clinicalsignificance of ICT used for the rapid diagnosis of community-acquired Streptococcuspneumoniae infections.Methods:1. We collected63patients with CAP in the Affiliated Hospital of Dalian MedicalUniversity from July2011to March2012, among them54cases of patients reservesputum samples and urine samples.2. Sputum samples from54patients with CAP were analyzed by culture.3. Urine samples from54patients with CAP were analyzed by ICT. 4. Streptococcus pneumoniae mixed with the sputum of those patients thensemi-quantitative cultured.The experimental group: The diluted4gradient ofStreptococcus pneumoniae suspension mixed with sputum samples from15patientswith CAP, then semi-quantitative culture in blood agar. The control group: the sameconcentration of pure strains of Streptococcus pneumoniae suspension was diluted to4gradient，then semi-quantitative culture in blood agar. Compared the two culture results:E. coli and P.aeruginosa mixed with sputum samples respectively in accordance withthe same method, then underwent semi-quantitative culture, observed bacteria growthand whether there are differences.Results:1. A total of54sputum samples from patients with CAP were assessed. Theculture findings revealed that5of the54sputum samples were positive.The pathogenicbacterias consist of candida albicans (9.26%)、Klebsiella pneumoniae(3.71%)、Bauman Acinetobacter(1.85%)、 Escherichia coli(1.85%), and no streptococcuspneumoniae was detected, including1case of Bauman Acinetobacter and candidaalbicans of mixed infection, accounted for1.85%.2. Measured by ICT in54urine samples the results show, the positive ratewas5.56%(3/54), and48specimens in54were analyzed by ICT and sputum culture.Among them the positive rate of ICT was6.25%(3/48), but the sputum culture had noStreptococcus pneumoniae found (positive rate was0%), there were no significantdifference (P>0.05).3. When the colony counts of streptococcus pneumoniae ranged from10~3to10~5（CFU/ml），as compared with the control group the growth number of streptococcuspneumoniae mixed with15septum samples in the experimental group decreasedsignificantly（P<0.01）;When the colony counts of streptococcus pneumoniae is102cfu/ml,the growth of it between two groups has no significant difference. E. colimixed with sputum experimental results: there were no significant difference in thegrowth of the bacteria between the experimental and control group in three calculableconcentration gradients ranged from102-104cfu/ml（P＞0.05）.Conclusion:1. This research shows that using ICT could improve the detection ofstreptococcus pneumoniae, but the positive rate of ICT is not high, and the clinicalapplication value has to be studied further.2. The culture of sputum samples from54CAP patients was negative for Streptococcus pneumoniae. According the culture results by mixing streptococcuspneumoniae into sputum specimens, we concluded that sputum may inhibit the growthof streptococcus pneumoniae.