An Investigation Of Gram-Positive Bacteria Infection In An Intensive Care Unit And Study On The Resistance In Part Of The Staphylococcus

Part I An investigation of Gram_positive bacteria infection in an intensive care unitBackground General intensive care unit (ICU) patients with serious condition,Immunocompromised and need to operate a variety of invasive treatment,antibiotics, immunosuppressant,which increase the risk of infection in patients. In recent years,ICU infection found growing phenomenon and Gram-positive (G +) bacteria reported infection caused by increasing year by year, Unreasonable application of antibiotics to produce a large number of resistant strains,Which has been the attention of clinicians.OBJECTIVE To retrospectively investigate the risk factors, distribution,antibiotic resistance of infection with G~+ bacteria intensive Care Unit (ICU), so as to provide the reference for clinical prevention and treatment.METHODS A retrospective analysis of clinical date of 83 patients with G~+ bacteria infection in ICU from January 2003 to December 2008 was doneRESULTS Of the 125 strains of G~+ bacteria from 83 patients, Staphylococcus were main (63.2%,79/125). The prognosis of the patient was relative with opration of surgical operation(χ~2=9.107 ,P=0.003), gastric tube(χ~2= 4.053 ,P=0.044), complication(χ~2= 5.908 , P=0.015 ) and the use of immunosuppressant (χ~2= 5.761 ,P=0.016).Multi_bacterial infection was ralative with tracheotomy(χ~2= 10.445 ,P=0.001)and surgery(χ~2= 8.847 ,P=0.003).The antibiotic susceptibility test in vitro showed that G~+ displayed multi-resistance to antibiotics, but all of G~+ bacteria were sensitive to vancomgcin (resistance rate was 0).CONCLUSION Staphylococcus was the most commmon pathogen of G~+ bacteria in ICU. Further surveillance of bacterial resistance is warranted in ICU, and antimicrobial druge should be used according to the result of susceptibility testing. Taking account of the antibiotic resistance and risk factors of G~+ bacteria infection in ICU, the infection could be controlled and the death rate could be cutted down when appropriate measures are taken.Part II Study on the Resistance in Part of the coagulase-negative Staphylococcus in an intensive care unitBackground Staphylococcus haemolyticus and Staphylococcus epidermidis are common in coagulase-negative Staphylococcus (CNS) and the detection rate is increasing,they has become the main hospital infection pathogens .MRCNS are not only resistant to Methicillin but also resistant to most antimicrobial agents. Resistance mechanism depend on mecA gene.Staphylococcus efflux pump system can be will enter the cells pump out antibiotics within the extracellular, thereby reduce the concentration of bacteria in vivo drug which led to drug resistance.the existence of multiple drug efflux transmembrane protein-NorA proteinin membrane of Staphylococcus,NorA protein encoded by the norA gene,the related sequences is also present on Staphylococcus epidermidis,which is a multi-drug resistance transporter of Staphylococcus protein.Currently, the expanded use of these antibiotics has resulted in emergence of S. haemolyticus resistance to glycopeptides.Objective The detection of mecA in Staphylococcus Haemolyticus and norA in Staphylococcus epidermidis had done in this research.to give references for inhabiting Staphylococcus Haemolyticus and Staphylococcus epidermidis are resistant to antibiotics. Susceptibilities were tested by agar dilution method,to provide the basis for rational use of antimicrobial agents.Methods 8 clinical isolates of Staphylococcus Haemolyticu and 6 clinical isolates of Staphylococcus epidermidis were collected from ICU. MRSH were detected by cefoxifin disc test. Susceptibilities were tested by agar dilution method. Results were analyzed according to CLSI 2008. mecA gene and norA gene were amplified by means of PCR ,the nucleotide sequences of NorA gene were analyzed by sequencing.Results 5 and 6 of isolates were MRSH detected by mecA-PCR and cefoxifin disc test. norA gene was detected in 4 isolates, Staphylococcus epidermidis strains and sequencing had none abnormality. Staphylococcus Haemolyticus and Staphylococcus epidermidis were resistant to most of antimicrobial agents , All isloates were susceptible to vancomycin and teicoplanin.Conclusions Staphylococcus Haemolyticus and Staphylococcus epidermidis were resistant to most of antimicrobial agents, All isloates were susceptible vancomycin,teicoplanin; cefoxifin disc test and mecA-PCR both can detecte MRSH; no matter resistant to fluoroquinolones, Staphylococcus epidermidis can detecte norA gene .