| Bacterial respiratory tract infections are common and frequently-occurring disease in clinic. As the changes of disease spectrum, the utility of new technologies and experiential usage of drugs, there are more and more respiratory tract infections caused by pathogenic bacteria, which increasingly resistant to antibiotics. Klebsiella pneumoniae is one of the most common bacteria which caused the respiratory tract infection and hospitalized infection.In recent years, with the extensive use of carbapenem antibiotic, meropenem-resistant or imipenem-resistant Enterobacteriaceae appeared. Once klebsiella pneumoniae produced carbapenemase, it could almost resistant to all antibiotics which producing beta-lactamase.Our study is to investigate the epidemiological features amd clinical characteristics of respiratory tract infection bacterium in shanghai pulmonary hospital, especially to understand the prevalence of Klebsiella pneumonia, resistance of antibiotics and molecular biological characteristics of klebsiella pneumoniae, to explore the risk factors and molecular biological mechanisms of the spread of KPC resistant bacterium, to provide a scientific basis for control of antimicrobial agents in clinic. Our study consisted of three parts:Part I:Epidemiological study of respiratory tract bacterial infection in hospitalized patientsObjective:To investigate the infection spectrum, drug resistance, clinical characteristics and risk factors of bacterial respiratory tract infection of hospitalized patients in shanghai pulmonary hospital, and to provide the basis for effectively controlling of clinical bacterial infections.Methods:A cross-sectional study was conducted in the department of respiratory and thoracic surgery within three consecutive months. The subjects were all the suscepted respiratory infecion patients and sputum specimens were collected for culturing and testing. To understand the infection positive rate, bacteria spectrum and the distribution of drug resistance and to analyze the major risk factors of bacterial respiratory tract infection by culturing, drug-resistant testing, questionnaire and so on.Results:A total of1865patients were recruited,1290of who had collected the sputum specimens. Finally,249isolates were obtained, The infection positive proporation is19.30%. Among the249isolates, there were137(55.0%) klebsiella pneumoniae,30(12.0%) pseudomonas aeruginosa,30(12%) Acinetobacter baumannii,15(6.0%) Enterobacter cloacae,8(3.2%) Escherichia coli, one Staphylococcus aureus and28(11.2%) other bacteria. Of the249patients,29(9.6%) patients were from TB department,31(18.8%) from pneumoconiosis department,21(7.0%) from respiratory department,65(14.85) from oncology and101(15.3%) from thoracic surgery department. There were statistically differences in the proportion of bacterial infection between different departments(Χ2=70.347,p=0.000). Pneumoconisosis department had the highest detection proportion among all departments, followed by thoracic surgery and oncology departments; there were significant differences in pathogen detecion proportion among different age groups (Χ2=17.634, p=0.001). The rate was higher as the age was elder. Among positive cases,172(22.9%) were retired,68(14.4%) were in serving and4(8.2%) did not have job. The pathogen infection proportion is different in various occupational status, the infection proportion is higher in retired patients than others (x2=18.060, p=0.000); out of the249patients,178(14.5%) were male and69(10.8%) were female, there was no statistically significant difference between male and female (Χ2=2.784, p=0.095). Drug susceptibility test will be performed for16kinds of medicine.130isolates of klebsiella pneumoniae were susceptible to Ampicillin/sulbactam, the proporation of drug susceptibility for Ampicillin/sulbactam was86.9%, for Amikacin was93.4%, Aztreonam was89.8%, Ciprofloxacin was92.7%, Ceftriaxone was89.1%, Cefazolin was83.9%, Ertapenem was93.4%, Cefepime was89.1%, gentamycin was91.2%, imipenem was92%, levofloxacin was92%, SMZ-TEM was85.4%, Ceftazidime was88.3%, and Tobramycin was92%. The proportion of drug resistance was90.5%for Ampicillin. Out of the30isolates of pseudomonas aeruginosa, the drug susceptibility of Aztreonam, Ciprofloxacin, Cefepime, gentamycin, imipenem, levofloxacin, Ceftazidime, Tobramycin were respectively100%,96.7%,96.7%,100%,93.3%,90%,100%, and100%. The drug resistant proportion for Ampicillin, Ampicillin/sulbactam, Cefazolin, Nitrofurantoin, SMZ-TEM were100%,100%,96.7%,100%and100%respectively. Of the30isolates of Acinetobacter baumannii, the proportion of drug susceptibility was following:Ampicillin/sulbactam (86.7%), Amikacin (96.7%), Ciprofloxacin (83.3%), Cefepime (86.7%), gentamycin (83.3%), imipenem (86.7%), levofloxacin (86.7%), SMZ-TEM (80%), Ceftazidime (86.7%) and Tobramycin (90%). While the proportion of drug resistance for Ampicillin, Ceftriaxone, Cefazolin and Nitrofurantoin were96.7%.Analyze the clinical characteristtics of bacterial respiratory tract infection, we found that it is no difference between man and women in using the antibiotics before addmission:(x,2=4.934,p=0.294); there was statistical differences among different age groups (x2=26.734,p=0.045),which the proportion of using one kind and more than three kinds of antibiotics for50-age group were respectively37.8%and38.9%. there was also statistical difference among different wards (Χ2=307.76, p=0.000), the proportion of using one kind of antibiotic were:breathing section (31.6%), Oncology (27.6%), chest Surgical (ICU)(21.4%), TB section (19.4%)and pneumoconiosis section (0%); the proportion of using two kinds of antibiotics were:respiratory (38.9%), tuberculosis (29.2%), Oncology (26.4%), thoracic surgical (ICU)(5.6%), Pneumoconiosis (0%). Uni-variant showed that age (x2=17.634,p=0.001), lung Surgery (Χ2=6.259, p=0.012), bronchoscopy (Χ2=6.707,p=0.010),and ventilator (Χ2=8.537,p=0.003) after admission are related to the bacterial respiratory tract infection. Gender, number of hospitalization and clinical characteristics before hospitalization such as lung resection, tracheal microscope operation, lung puncture intubation, using of hormone, pleural effusion, chemotherapy, radiotherapy and diabetes has no statistically significance.Conclusions:The positive detection rate of sputum specimens was19.3%in Shanghai pulmonary hospital. The detection rate of the Gram negative bacterium was more than80%, which was higer than literature reports.130isolate of klebsiella pneumoniae were susceptible to most of antibiotics, while drug resistant rate for ampicillin was90.5%. The30pseudomonas aeruginosa were sensitive to most antimicrobial agents, while completely resistant to ampicillin, ampincillin/sulbactam, cefazolin; the30Acinetobacterbaumanii isolates were resistant to ampicillin, ceftriaxone and cefazolin. So, we should avoid using the antibiotics which were not sensitive in clinic. There was statistically significance in using antibiotics among different department, the respiratory department was highest, while the pneumoconiosis department did not use antibiotics. So it is helpful to use antibiotics rationally and earlily to control bacterial infection. Lung surgery after admission, bronchoscopy and ventilator were related to the bacterial respiratory tract infection, showed that invasive test and treatment after admission could easily cause respiratory tract infection, so the equipments should be well disinfected and sterilized in clinic.Part II:Study on the characteristics of drug resistance-related gene of Klebsiella pneumoniaeObjective:To investigate the antimicrobial susceptibility and genotyping of plasmid mediated extended spectrum beta lactamases (ESBLs) and AmpC beta lactamases (pAmpC) in Klebsiella Pneumoniae (Kpn) isolated from lung hospital of Shanghai.Methods:A total of211Kpn strains were collected from department of medical clinical laboratory within Three consecutive months in2012. The suceptibiltiy to antibitoics was detected by Microscan MIC method. The PCR and DNA sequencing methods were used to determine the genotypes of ESBLs and pAmpC.Results:. Of the studied211KPn strains,78were identified to produce the ESBLs. All the ESBLs producing strain were resistant to ampicillin, significantly higher than those without producing ESBLs (100%.vs.77.4%, p=0.0001).A significant high proportion of ESBLs producing strain were resistant to aztreonam (20.5%.vs.0.8%, p<0.05) and ceftazidime injection (15.4%.vs.1.5%, p<0.05). Meanwhile, the AmpC-producing strains showed the reduced susceptibility to aztreonam, ceftazidime injection, ciprofloxacin and amikacin. Furthermore, Comparing different type ESBLs resistance-related genes on the rate of antibiotic resistance. All SHV-positive strains of ampicillin resistance are clearly higher than that of SHV-negative strains, there is a statistically significant (100%.vs.75%, x2=26.52,p=0.0001),the rate of TEM-positive strain to ceftazidime-resistant is significantly higher than that of TEM-negative strains (10.3%.vs.2.4%,Χ2=4.l9, p=0.041), drug resistance rate of ceftazidime (13.5%.vs.4.0%, x2=5.12,p=0.024) and aztreonam (16.2%.vs.4.6%,Χ2=6.65,p=0.001) is higher in CTX-positive strains than in the CTX-negative strains, a statistically significant difference occurs.Conclusions:The prevalence of ESBLs-producing Klebsiella pneumoniae bacteria in the region is very serious. It shows that Klebsiella pneumoniae in clinical isolates is active in the main SHV-1and TEM-type ESBLs. Through detection of ESBLs gene of ESBLs-producing enzyme from Klebsiella pneumoniae and ampC gene of AmpC-producing enzyme, some guidance of rational prescription for clinicians are provided.Part Ⅲ:study on Gene typing of Klebsiella pneumoniae strain and characteristics of the epidemic Objective:The genetic diversity and the clinical relevance of the drug-resistant Klebsiella pneumoniae isolates from hospital settings are largely unknown. We thus conducted this prospective study to analyze the molecular epidemiology of K. pneumoniae isolates from patients being treated in the lung hospital in Shanghai, China.Methods:Antibiotic susceptibility testing, PCR amplification and sequencing of the drug resistance associated genes, and multilocus sequence typing (MLST) were conducted.Results:A total of211isolates were analyzed. MLST results showed that94sequence types (STs) were identified, which were further separated by eBURST into13clonal complexes and18singletons. The most dominant ST was ST15(10.4%). Seven new alleles and24new STs were first identified in this study. Multiple logistic regression analysis revealed that certain clinical characteristics were associated with those prevalent STs such as:from ICU, from medical ward, from community acquired infection, from patients without heart disease, from patients with treatment success, susceptible to extended spectrum cephalosporin, susceptible to cephamycins, susceptible to fluoroquinolones, and with MDR.Conclusions:Our data indicate that certain drug-resistant K. pneumoniae clones are highly prevalent and are associated with certain clinical characteristics in hospital settings. Our study provides evidence demonstrating that intensive nosocomial infection control measures are urgently needed. |
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