To analyze the characteristics and drug resistance of pathogenic bacterium of community acquired acute lower respiratory infection(ALRI) in children in Dianjiang county, Chongqing, and to provide basis of rational use of antibacterials for clinical practice.

A total of 1 960 children who made definite diagnosis of community acquired ALRI and hospitalized in department of Pediatrics, Dianjiang People's Hospital of Chongqing from July 1, 2013 to June 30, 2014 were chosen as study subjects.They were divided into 3 groups: <1 year old group(n=936), ≥1-3 years old group(n=662) and ≥3-14 years old group(n=362)in accordance with age stage. Using clinical routine sputum collecting method to collect sputum and doing vaccination, separation culture, bacteria identification and drug sensitive test before use antibacterials.Compare the differences of positive rate and constituent ratio of pathogenic bacterium of sputum culture results in different age stages and to summarize the drug resistance of main pathogenic bacterium to frequently used antibacterials.The study protocol was approved by the Ethical Review Board of Investigation in Human Being of Dianjiang People's Hospital of Chongqing.Informed consent was obtained from the parents of each participant.There were no significant differences among three groups in gender constituent ratio and time from onset to admission(P>0.05).

①Positive rate of pathogenic bacterium of sputum culture in younger age groups were higer than those in elder age groups, and there were significant differences(P<0.001). ②Top 4 main pathogenic bacterium of sputum culture were 528(33.7%) strains of Streptococcus pneumonia, 332(21.2%) strains of Hemophilus influenza, 234(14.9%) strains of Moraxelle catarrhalis and 133(8.5%) strains of Staphylococcus aureus in descending order. ③Among 3 groups, Streptococcus pneumonia proportion in sputum culture increased with age while common Gram negative (G^-)bacillus proportion decreased with age, and there were significant differences(P<0.017); Moraxelle catarrhalis proportion in ≥1-3 years old group was higher than that in <1 year old group, and Staphylococcus aureus proportion in <1 year old group was the highest one in 3 groups, and there were significant differences (P<0.001); There were no significant differences among 3 groups in Hemophilus influenza proportion(P>0.05). ④There were 9 pathogenic bacterium species in ≥3-14 years old group, and 20 species in <1 year old group.The older of children, the less pathogenic bacterium species in sputum culture.⑤Except drug resistance rates of Hemophilus influenza, drug resistance rates of other main pathogenic bacterium, including Streptococcus pneumonia, Moraxelle catarrhalis, Staphylococcus aureus, Pneumonia subspecies of K. Pneumoniae, Escherichia coli and Hemophilus parainfluenzae on some frequently used antibacterials were more than 50.0%, especially Staphylococcus aureus, it had a variety of frequently used antimicrobial drug resistance and their drug resistance rates were more than 90.0%.

The main disease producing germ of community acquired ALRI in children in Dianjiang county, Chongqing were bacteria, and bacterial drug resistance is obvious. Streptococcus pneumoniae infection rate was the highest.The younger children, the more pathogenic bacterium species in sputum culture, and the higher of infection rates of Staphylococcus aureus and G^- bacillus. We should establish monitoring system to monitor disease producing germ of community acquired ALRI in children in Dianjiang county to proceed epidemiological investigation and to guide the clinical rational use of antibacterials.