Retrospective Investigation Of Nosocomial Infections Caused By Non-fermenting Bacteria In ICU And The Detection About Acinetobacter Baumannii Of The β-lactamase

Objective1. To investigate the actual reality about the popularity of the Non-fermenting Bacteria in ICU, analyze their antimicrobial resistance situation.2. To investigate the risk factors concerning about the complex infections and the disease prognosis in ICU, the correlation between the clinical experience and multi-drug resistant bacteria.3. To study theβ-lactamase resistance of multi-resistant Acinetobacter baumannii species in ICU and analyze their associated resistance mechanism and guide rational use of antibiotics.Materials and Methods1. A retrospective investigation was carried out on 91 non-fermenting bacteria infected patients in ICU and analyse their antimicrobial resistance situation.2. To make a statistical research with SPSS 13.0 software. Firstly make analysis about the latent risk factors about theχ~2 test. Secondly multivariate Logistic Regression analysis were used to analyse the risk factors for complex infections, the risk factors for disease prognosis, and the correlation analysis between the experimental use of usual medicine and multi-drug resistantbacteria.3. To collect the Acinetobacter baumannii and the M-H agar dilution method was used to determine MICs of 14 antimicrobial agents against 43 clinical isolates of Acinetobacter baumannii species isolates.4. Multi-resistant strains of bacteria DNA extracted by boiling method,specific fragment of carbapenemases gene and extended-spectrumβ-lactamases gene were amplified by PCR to reveal the existence ofβ-lactamase. The results about the nucleotide sequence are examined in the GenBank for comparison.Results1. From the ICU nosocomial infection in non-fermenting bacteria are divided into 91 patients of 150 strains of bacteria, including Acinetobacter baumannii accounting for 38.7%, 26.7% Pseudomonas aeruginosa, Stenotrophomonas maltophilia accounting for 22.0%, those three kinds of non-fermenting bacteria are mainly accounted for 87.4%, other 12.6% of other non-fermentating bacteria. The main site of infection is the respiratory system. Resistant Acinetobacter baumannii is 22.4% -89.1%, with lower rates of antibiotic resistance to imipenem, lomefloxacin; Pseudomonas aeruginosa resistance rate is 27.0% -97.1%, resistance low rate of antibiotic drugs is amikacin, cefepime; Stenotrophomonas maltophilia resistant to 6.2% -100%, with low rate of antibiotic resistance is a lomefloxacin, ciprofloxacin, ceftazidime, others showing highly resistant.2. By multiple analysis, deep venous catheter which is a independent risky factor lead to complex infection(χ~2=5.977, p=0.014); ventilator, indwelling stomach tube,thoracic drainage has a direct relationship between the disease outcome (χ~2=5.239,p=0.022;χ~2=4.405,p=0.036;χ~2=4.242,p= 0.039); Imidazole antifungal agents and the occurence of multi-drug resistance had a close relationship(χ~2=4.571,p=0.033).3. Acinetobacter baumannii to penicillins, cephalosporins, aminoglycosides, quinolones or carbapenems resistant to many antimicrobial agents at the same time. By PCR amplification of IMP-1, VIM-1, VIM-2 and SIM-1 gene to detect the presence of metal enzyme genes, of which 6 IMP-1 is positive, not detected VIM, SIM metal enzyme genes. 17 OXA-23 positive strains, 5 strains of the same time with OXA-23 type enzyme, and IMP-1 type enzyme. Other ESBLs encoded gene amplification are negative. 6 IMP-1 and 17 OXA-23 positive products to do DNA sequencing BLASTn comparison of the gene pool has the same name with the gene sequences.Conclusion1. Nosocomial infection in ICU of our hospital with non-fermentative bacteria is according to the reports, mainly Acinetobacter baumannii. Non-fermenting bacteria resistant bacteria requires clinicians to increase the drug resistance of bacteria to monitor changes over attention, a reasonable choice of antibiotics to reduce the occurrence of bacterial resistance. This study shows that ICU non-fermentative bacteria within the complex and deep venous catheter infection is directly related to infection and that disease outcome is closely related with a variety of invasive treatment. Therefore, to improve the ICU management system, pay attention to disinfection and sterilization equipment, intensive care and sterile concept of medical personnel, pay attention to the isolation and other infection can all efficiently reduce the ICU nosocomial infection.2. OXA-23 carbapenemase and IMP-1 enzyme is a metal multi-drug resistance within ICU, the MDR Acinetobacter baumannii toβ-lactamase antibiotics, carbapenems important mechanism of antimicrobial drug resistance; those will promote the spread of drug resistance , therefore, one must promote the attention of the rational use of antimicrobial agents.