Pathogenic Bacteria Distribution Of Lower Respiratory Tract Infection And Drug Resistance Analysis In A Top One Hospital During The Last Two Years

According to the World Health Organization statistics in 2007, Millions of people suffer from resistant Staphylococcus aureus infection worldwide every year. About 30% of them eventually died. The death rate is even higher than that of HIV. China is one of the countries worst abuse of antibiotics. Hospital antibiotic usage of the developed countries is about 20%. In China, it is more than 60%. Irrational use of drugs and iadequate understanding of the consequences of drug resistance are the main reasons of the high rate of drug resistance. Therefore, to monitor bacterial resistance and to make clear types and drug resistance of pathogens of various infections have great significance in guiding rational use of drugs in clinical and public and slowing down the generation and spread of resistant strains. Lower respiratory tract infections are the most common infectious diseases. The use of antibiotics in these diseases is often the most serious. Therefore, we conducted routine bacterial culture of sputum samples of patients with lower respiratory tract infection of respiratory department and geriatrics department in our hospital from 2009 to 2010. we conducted identification and susceptibility testing with pure strain cultured using automated microbial identification system VITEK 2 COMPACT. We found that the positive rates of continuous sputum cultivation of geriatrics department were Significantly higher (2009:56.3%; 2010:50.8%)than that of respiratory department (2009:28.8%; 2010:36.0%)(p<0.01) and the positive rates of continuous sputum cultivation of geriatrics department were Significantly higher (2009:56.3%; 2010:50.8%)than that of singal sputum cultivation (2009:26.2%; 2010:27.9%)(p<0.01). It suggested multiple submissions do help the detection of pathogens. Therefore, when treating patients with lower respiratory tract infection, especially critically ill patients, Clinicians should send multiple submissions while empiric treatment to get accurate information of pathogens and antimicrobial susceptibility. The study showed that gram-negative bacilli were the main pathogenic bacteria of lower respiratory tract infection (72.4% in 2009; 70.9% in 2010:).In the past two years,the top five of gram-negative bacteria were the same. It suggested that Klebsiella pneumonia subspecies pneumonia, Pseudomonas aeruginosa, Enterobacter cloacae, Escherichia coli and Acinetobacter baumannii are the most common types of bacteria in lower respiratory tract infection. Bacterial culture and susceptibility testing need 2 to 3 days, so clinicians should target these types of bacteria in early empiric treatment. And then make reasonable drug selection according to their microbiological effects and resistance surveillance of those bacteria in the regionESBLs (Extended Spectrum ?-lactamases) detection rate in Klebsiella pneumonia subspecies pneumonia don't change obviously.(23.1% in 2009; 29.3% in 2010)(p>0.05). ESBLs detection rate in Escherichia coli don't change obviously.(78.6% in 2009; 50.0% in 2010)(p>0.05)..Drug resistance rate is significantly higher in most ESBLs positive strains than in ESBLs negative strains (p<0.01) .Drug resistance rate in ESBLs(-)strains don't change obviously in last two years(p>0.05). Klebsiella pneumoniae ESBL(s-)strains is highly sensitive to most antibiotics except ampicillin and piperacillin; Escherichia coli ESBLs (-) strains is more resistant than Klebsiella pneumoniae ESBLs(-)strains,But it's sensitivity to Cephamycins, the third generation cephalosporins, the fourth generation cephalosporin and Enzyme alkene hydrocarbon remains high. Drug resistance rate in Klebsiella pneumoniae ESBLs(+)strain change obviously to Amikacin(p<0.05), Tobramycin(p<0.05) and Ciprofloxacin(p<0.05)in 2010. Drug resistance rate in Escherichia coli ESBLs(+)strain change obviously to Tobramycin (p<0.05).Drug resistance to Imipenem, meropenem, ciprofloxacin of Pseudomonas aeruginosa is relatively low,it's about 20%. It is moderately to highly resistant to Other drugs,and resistance rates of most antibiotics showed a rising trend in 2010 compared with 2009.There is no Enterobacter cloacae strains resistant to Piperacillin– tazobactam. It is also rather sensitive to enzyme alkenes hydrocarbon, quinolones and amikacin, Resistance rates are less than 10%. Enterobacter cloacae were highly resistant to penicillin, first -generation cephalosporin and second-generation cephalosporin. It showed moderate resistance to third generation cephalosporins,fourth generation cephalosporin,single ring antibiotics. And the resistant rate Increased significantly in 2010 compared with 2009,especially Ceftazidim(p<0.05), Aztreonam and Sulfamethoxazole(p<0.05). In clinical isolated Non-fermenting bacteria, Acinetobacter baumannii is just after Pseudomonas aeruginosa,and the detection rate of 2010 had a marked increase over 2009. This study showed there is no Acinetobacter baumannii resistant strains to Amikacin. However, Acinetobacter baumannii showed different degree of resistance to other antibiotics. Particularly in 2010, resistance rate to imipenem and meropenem, which are our senior clinical defense to treat Gram-negative bacilli Infection so far, is as high as 12.4%. Drug resistance rate change obviously to Ceftazidime(p<0.05), Cefepime(p<0.05), Gentamicin(p<0.05) and Trimethoprim/Sulfamethoxazole(p<0.05)in 2010..The proportion of gram-positive cocci is lower(18.0% in 2009; 17.7% in 2010).The top three were staphylococcus aureus, staphylococcus haemolyticus and staphylococcus epidermidis.Staphylococcus aureus, Staphylococcus epidermidis are relatively sensitive to Quinupristin/dalfopristin, linezolid, vancomycin, nitrofurantoin, and chloramphenicol;Staphylococcus haemolyticus showed a significant multiple, high resistance. It has no resistant strains only to linezolid and nitrofurantoin. The proportion of fungal infection is about 10%.In patients with lower respiratory tract infection,Gram-negative bacilli are almost resistant to penicillins, first-generation cephalosporin and second- generation cephalosporin; Gram-positive cocci are almost resistant to penicillins, first -generation cephalosporin,Erythromycin and clindamycin. Therefore, In order to avoid delay in treatment,to guard against unnecessary waste of medical resources and to prevent the emergence and spread of resistant bacteria, in clinical treatment and or public purchase in pharmacies, these drugs should not be used in treatment of lower respiratory tract infections.The study showed Lower respiratory tract infection pathogens are mainly Gram-negative bacilli. But both gram-negative bacilli and gram-positive cocci showed multiple, high drug resistance. There is significant difference in sensitivity to the same antibiotics between Enzyme production strains and non-enzyme production strains of the same specie. Different Bacterial species showed significant difference in sensitivity to the same antibiotics, too. Resistance rate of most pathogens showed a rising trend in 2010 compared with 2009. Therefore, clinicians should send Sputum culture as early as possible and repeatedly. Based on susceptibility results, clinicians can choose sensitive antibiotics in time,to improve the cure rate and reduce the production of drug-resistant strains.This study has the following characteristics and innovations1. We compared the influence of different submission times on detection rate. In this study, in geriatrics department group, sputum samples were sent for detection in the first three consecutive days from the date of admission.In respiratory department sputum samples were sent for detection just once on admission day,as we usually do.There are no such study design in China before.2. The main instrument used was automatic(VITEK 2 COMPACT) .It avoid human error in semiautomatic and manual operation. In susceptibility testing, the drugs we chose were very comprehensive. which covered A, B, C and D group of drugs recommended by National Committee for Clinical Laboratory Standards (NCCLS)and approved by U.S. Food and Drug Administration (FDA);And included major types of antibiotics commonly used in clinical in china.So the Susceptibility testing results of this study were fairly comprehensive and accurate. It had guidance and authority to some extent. Up to now,there are few comprehensive reports of drug sensitivity in china.