Analysis Of Drug Resistance Of Pathogens Of Nosocomial Infections In Critically Ill Patients And Risk Factors

Objectives To investigate the distribution and antimicrobial resistance trend of pathogens in patients from Emergency Intensive Care Unit(ICU)of Tianjin Medical University between July 2008 and Dec 2009, so as to provide theoretical bases of rational usage of antibiotics and experienced therapy for the clinic.Methods Distribution of the main pathogens isolated from all specimens of critical patients and antimicrobial susceptibility test results were analyzed retrospectively. Flora cultivation and isolation was operated with the methods described by the National Clinical Laboratory Operational Regulations.Bacterial identification was carried out using VITEK-AMS.Bacterial susceptibility testing was carried out using Kirby-bauey methods. Two kinds of disc diffusion sorcening test and phenotypic confirmatory test were used to detect Extended-Spectrumβ-Lactamases(ESBLs) in bacteria;The resistant rate of bacteria was analyzed according to the guidelines of the National Committee for Clinical Laboratory Standards. Data were analyzed with SPSS 17.0 software and ststistical methods including general descriptive methods, Compare the resistance rate in ESBLs-produced group and in non-ESBLs-produced group, then the data were tested by K-S method, which was shown to be in normal distribution.Results 1.738 strains of pathogenic bacteria were isolated from clinical samples during 2 years,among which there are 442 strains of Gram-negative bacilli among them,accounting for 59.5% in total clinical isolates; 96 strains of Gram-positive bacteria among them, accounting for 13.0% in total clinical isolates; 200 strains of fungus among them, accounting for 27.1% in total clinical isolates. The common Gram-negative bacilli were mainly Pseudomonas aeruginosa 116 strains(26.2%), Klebsiella spp 84 strains(19.0%), Escherichia coli 59 strains(13.3%),Acinetobacter baumannii 54 strains(12.2%), Enterobacter cloacae 30 strains(6.8%), The common Gram-positive bacilli were Enterococcus42strains(43.8%), Staphylococcus41 strains(42.7%). Methicillin resistant Staphylococcus accountde for 61.0% in total Staphylococcus. High concentration of Aminoglycoside resistant enterococci accounted for 78.6% in the total Enterococcus. No vancomycin-resistant gram-positive bacteria was found. The common fungus was Candida albicans, accounting for 80.0% in total clinical fungus isolates.2.77.0% pathogens are isolated from specimens in respiratory tract and 18.2% from than in urinary tract among 738 strains of pathogens, blood specimens only account for 2.4%.3. According to surveillance of drug resistance, the clinical antibacterial drugs with the lowest total drug-resistant rates of Gram-negative bacilli were imipenem and meropem.4. A total of 51 strains of ESBLs-produced bacteria were isolated, the detecting rate is 11.5%. They include 23 strains of Klebsiella pneumonia whose ESBLs-produced rate is 27.4% and 28 strains of Escherichia coli whose ESBLs-produced rate is 47.5%. Klebsiella pneumonia and Escherichia coli were predominant strains of ESBLs-producing. The resistance rates of ESBLs-produced strains to the common antimicrobial agents were Significantly higher than those of non-ESBLs-producing strains.5. Vancomycing and Nitrofurantoin are the most effective antibiotics against staphylococcus and enterococci.No vancomycin-resistant strains were detected.6. 5-flurocytosine Amphotericin B and Ketoconazole Capsules were the most active antibiotic against fungus.Conclusions 1. Respiratory tract is the main site where nosocomial infections occur in critically ill patients.2. Gram-negative bacterium is the main pathogenic bacteria in nosocomial infection, Invasive procedures and antibiotic use are independent risk factors of the multi-drug resistant strains of Pseudomonas aeruginosa.3. Third and fourth generation cephalosporins against gram-negative bacteria has good sensitivity, and the sensitivity ratio is over 50%. Imipenem and Meropenem against Gram-negative bacteria are most sensitive, and the sensitivity ratio is more than 95%. Vancomycin, linezolid against gram-positive bacteria are most sensitive, and the sensitivity ratio is above 94%. Amphotericin B,5 - fluorocytosine, fluconazole and ketoconazole have good sensitivity against fungal, and the sensitivity ratio is above 96%.4. Monitoring bacteria resistant, according to antimicrobial susceptibility test changes result chosing antibiotic adjust experience administration is very important.