The Role Of Hemophilies Influenzae In Children With Actue Respirtory Tract Infection And Analysis Of Drug Fast In Suzhou

Objectives To investigate the incidence,clinical characreristics,antibiotic resistance and mechanism of antibiotic resistance of Haemophilus influenzae(HI) in children with acute respiratory tract infection in Suzhou during 2006～2008.To determine the drug resistance gene of beta-lactamases antibiotic against Haemophilus influenzae,possible genetic mutation and the possible relationship between minimal inhibitory concentrations(MICs) of beta-lactamases against Haemophilus influenzae and genetic mutation.Methods The date of bacteria culture in sputum from January 2006 to December 2008 were collected.The incidence,biology grouping,characteristic,of HI and its tesistance rate to different antibacterials were calculated and beta-lactamases of these stratins were detected and drug activity were tested by K-B method against 12 antimicrobial agents,4 antibiotics MICs were determined by E-test.Beside,the beta-lactamases drug resistance genes were detected by net-polymerase chain reaction (nPCR) followed by DNAsequencing.The sequences of drug resistance genes were compared with the published sequence in GenBank.Results 4.7%of 4865 children with actue respiratory tract infected HI.The infection rate was related with season and sex.The infection rate in winter and spring was higher than that in summer and autumn.The rate of HI infection of boys was higher than that of girls.Children younger than three years old were likely infected by HI,compared with other age groups.The main bacteria which combined HI infection were Streptococcus pneumoniae,Moraxelle catarrhalis and Staphylococcus aureus.Among the isolated 4865, Biotypeâ…¡and biotypeâ…¢were the two most common ones.The beta-lactamase positive rate of HI was 32.6%,The beta-lactamase positive rate of Biotypeâ…¡was highest among other Biotypes,wich wsas 48.8%.The resistant rates to ampicillin,SMZ+TMP,Ceftazidime,Ceftriaxone,chloramphenicol,Azithromycin,cefaclor,Tetracycline and ampicillin/sulbactam were 29.6%～33.3%,66.2%～73.9%,0～4.6%,0～2.3%,15.9 %～19.7%,0～2.3%,2.8%～16.1%,2.9%～28.2%,1.4%～4.6%respectively. Isolates resistant to cefuroxime,imipenem and ciprofloxacin were not found.Among the multidrug resistance of HI,AM+ SMZ/TMP+ CL+ TC is the highest one,followed by AM+ CL+ TC and SMZ/TMP+ CL+ TC.The rate of AM+ SMZ/TMP+ CL+ TC,AM+ CL+ TC and SMZ/TMP+ CL+ TC was 76.0%.The resistant rates to Tetracycline,SMZ+TMP and chloramphenicol in ampicillin insensitivity HI was higher than that of ampicillin sensitivity HI.The MIC₉₀ and MIC₅₀ of HI to ampicillin,ampicillin/sulbactam,cefaclor and chloramphenicol were(32ug/ml,1 ug/ml),(2ug/ml,0.75ug/ml),(24ug/ml,2ug/ml) and(8ug/ml,0.5ug/ml) respectively.Among the isolated 4865,TEM gene were detected in 53 HI.Beta-lactamase geneTEM was detected in 39.3%of HI.No ROB gene was detected.28.3%of TEM gene had been Mutated.The mean minimal inhibitory concentration of beta-lactamases antibiotic in HI that had mutant TEM gene were higher than that of no mutant TEM gene.Conclusions(1) HI is one of the most common pathogen of acute respiratory infection(ARI) in children,whose infection rate was only lower than that of Streptococcus pneumoniae.(2) The infection rate in winter and spring was higher than that in summer and autumn.Children younger than three years old were likely infected by HI,compared with other age groups.The rate of HI infection of boys was higher than that of girls, especially in spring and winter.(3) All kinds of biotypes could been detected in suzhou, Biotypeâ…¡and biotypeâ…¢were the two most common ones.The beta-lactamase positive rate of HI was 32.6%,The beta-lactamase positive rate of Biotypeâ…¡was highest among other Biotypes.(4) The resistant rates to ampicillin,SMZ+TMP and chlormycetin werw high,some isolates resistant to the second and thidrd generation cephalosporin and the rate of multidrug resistance were 22.0%.(5) Beta-lactamase geneTEM was detected in 39.3 %of HI.No ROB gene was detected.28.3%of TEM gene had been Mutated.The mean minimal inhibitory concentration of beta-lactamases antibiotic in HI that had mutant TEM gene were higher than that of no mutant TEM gene.