Study Of Streptococcus Viridans Impact On Streptococcus Pneumoniae From Sputum Samples Of Community-acquired Pneumonia Patients

Objective:Community-acquired pneumonia(CAP) is a common infectiousdiseases which has a high morbidity and mortality in the worldwide. The present studiesshowed that Streptococcus pneumoniae is the most important pathogens of CAP.It isconvenience that collect Sputum samples,Sputum specimens are the most commonlower respiratory tract pathogen detection specimens, but the positive rate of sputumculture was lower.In this study,hospitalized adult community-aquired pneumoniapatients conducted bacterial culture， Streptococcus pneumoniae mixed withStreptococcus viridans which were isolated from sputum and underwentsemi-quantitative culture.The purpose of the experiment is to explore the reasons of thelower positive rate of bacterial culture for Streptococcus pneumoniae from sputumsamples of patients with CAP.Methods:1.We recruited adult community-acquired pneumonia patients whoattended to Dalian medical university affiliated hospital between July2011and Marth2004, bacterial culture and identification of microorganisms isolated from sputumculture were done.2.We mixed the streptococcus pneumoniae with streptococcus viridans isolatedfrom the sputum,and conducted semi-quantitative culture.The experimental group did ahalf quantitative culture of streptococcus pneumoniae mixed with streptococcus isolatedfrom sputum in blood plates,and observed the growth situation of streptococcuspneumoniae;The control group mixed streptococcus pneumoniae of the sameconcentration as experimental group with physiological saline solution,and did a halfquantitative culture of it in blood plates, then we compared the difference of the growthsituation of streptococcus pneumoniae in two groups. Results:1.54of63cases did sputum bacterial cultures,the positive rate of sputumcultures were20.37%(11/53),with5pathogens isolated in total, Escherichia coli3.7%(2/54),Candida albicans accounting for9.26%(5/54),Klebsiellapneumoniae,3.7%(2/54), Acinetobacter baumannii bacteria3.7%(2/54),smoothCandida1.85%(1/54). streptococcus pneumoniae0%（0/54）.2.Streptococcus pneumoniae mixed with A group streptococcus viridians(concentration of10~8cfu/ml) semi-quantitative culture results: as compared with thecontrol group the growth number of streptococcus pneumoniae,streptococcus viridiansin a concentration of10~7、10~5cfu/ml respectively mixed with streptococcus pneumoniaein a concentration of10~6、10~4cfu/ml,the growth of streptococcus pneumoniae decreasedsignificantly（P＜0.05）,streptococcus viridians in a concentration of10~6、cfu/ml mixedwith streptococcus pneumoniae in a concentration of10~5cfu/ml,the growth ofstreptococcus pneumoniae decreased significa-ntly,but there was no significantstatistically difference(P=0.241);When we mixed streptococcus viridians in aconcentration of10~6、10~5、10~4、10~3、10~2cfu/ml respectively with the same concentrationof streptococcus pneumoniae,there were no significant difference in the growth ofstreptococcus pneumoniae between the experimental and the control group(P＞0.05);When we mixed streptococcus viridians in a concentration of10~5、10~4、10~3、10~2、10~1cfu/ml correspondingly with streptococcus pneumoniae in the concentration of10~6、10~5、10~4、10~3、10~2,there were no significant decrease of the growth of streptococcuspneumoniae in both the experimental and the control group(P＞0.05).Conclusion:Streptococcus viridans may inhibit the growth of Streptococcuspneumoniae,perhaps this is the one of the reasons.which leads to low positive rate ofsputum culture of Streptococcus pneumoniae of community-acquired pneumoniapatients.