Study On Distribution And The Resistance Of Clinical Isolates Of Gram-Negative Bacilli In A Hospital, 2001 To 2005

Objective: To investigate the distribution and antimicrobial resistance of Gram-Negative bacilli from patients in a Hospital, and provide reference for the clinical diagnosis and treatment of bacterial infection.Methods: bacilli isolated from The Hospital from 2001 to 2005 were collected. Flora cultivation and isolation was operated with the methods descripted by the National Clinical Laboratory Operational Regulations. Bacterial identification were carried out using VITEK-32. Bacterial susceptibility testing were carried out using Kirby-bauey methods; Two kinds of disc diffusion screening test and phenotypic confirmatory test were used to detect Extended-Spectrumβ-Lactamases (ESBLs) in bacteria; The resistant rate of bacteria according to the guidelines of the National Committee for Clinical Laboretory Standards(NCCLs, 2000), and date were analysed with WHONET 5.0 software what were provided from monitoring network of bacterial resistant in World Health Organization and SPSS 13.0.Results:1. 9092 strains of bacilli were isolated from clinical samples in five years, 6389 strains of Gram-negative bacilli among them, accounting for 70.3% in total clinical isolates. 2. The common Gram-negative bacilli were mainly Pseudomonas aeruginosa(1748stains, 27.4%),Escherichia coli(1404stains, 22.0%),Klebsiella pneumoniae (1395stains, 21.8%),Acinetobacter sp(522stains, 8.2%) and Enterobacter cloacae (395stains, 6.2%)in turn. The ESBLs positive rate of Gram-negative bacilli were 35.9%(504/1404) in Escherichia coli, 38.2%(533/1395) in Klebsiella pneumoniae.3. above 50% from respiratory tract and above 13% from urinary tract among 5464 strains of the common Gram-negative bacilli.4. Above 25% from The older-person units among Gram-negative bacilli, followed by respiratory unit and ICU.5. According to our surveillance, the clinical antibacterial drug-resistance rates of Gram-negative bacilli was not prominent to cefpodoxime and imipenem (P＞0.05). the clinical antibacterial drug with the lowest total drug-resistance rates of Gram-negative bacilli was imipenem(＜15%)followed by cefoperazone/sulbactam(＜20%), while that with the highest resistance was ampicillin(＞80%).6. The drug-resistance rates of Escherichia coli was not prominent to Ceflazidime, cefpodoxime,Piperacillin-tazobactam,amoxicillin-clavulanic acid (P＞0.05). The drug-resistance rates of Klebsiella pneumoniae was not prominent to cefpodoxime and imipenem. The drug-resistance rates of Enterobacter cloacae was prominent to cefoxitin,Cefaclor,amikacin,Ticarcillin-clavulanic acid (P＜0.05). Imipenem was the most active antibiotic against Escherichia coli,Klebsiella pneumoniae and Enterobacter cloacae, the susceptibility rate were above 97%, Escherichia coli and Klebsiella pneumoniae showed the drug-resistance rates below 30% to Ceftazidime,Piperacillin-tazobactam and cefoperazone-sulbactam, while the drug-resistance rates of Enterobacter cloacae (about 40%)was much higher than Escherichia coli and Klebsiella pneumoniae. All of them show higher drug-resistance rate to Trimethoprim-sulfamethoxazole(61.4%～86.5%)。7. The drug-resistance rates of Pseudomonas aeruginosa was prominent to all drug except Cefaclor (P＞0.05). The drug-resistance rates of Acinetobacter sp was prominent to all drug(p＜0.05). cefoperazone-sulbactam and imipenem were more active antibiotic against Pseudomonas aeruginosa and Acinetobacter sp in nonfermertative Gram-negative bacilli, the susceptibility rate of Pseudomonas aeruginosa were 7.0%～22.2% and 11.2%～21.4%, while the susceptibility rate of Acinetobacter sp were 5.0%～21.2% and 3.6%～16.2%, respectively. Pseudomonas aeruginosa showed the drug-resistance rates above 90% to amoxicillin and amoxicillin-clavulanic acid, while Acinetobacter sp showed the drug-resistance rates above 70% to Cefaclor.8. The resistance rates of ESBLs-producing straints to the common antimicrobial agents were much prominenter than those of non-ESBLs-producing straints(p＜0.05).Conclusion: Gram-Negative bacilli were very prominent in pathogens of nosocomial infection in five years. It become more common and is highly resistant to commonly used antimicrobials(P＜0.05). It is very important to monitor the distribution of bacteria and their resistance to antibiltices. The drug-resistance study help to find out the sensitive drugs for clinical application, thus to bring down the growth of drug-resistance rate of bacteria.