Displacement ventilation is described from the aspects of its primary principle, characteristics and differences from the traditional one. The factors that have to be taken account into when a displacement ventilation system designed are also discussed.

Objective To investigate perioperative antimicrobial prophylaxis in arthroscopic surgery in a hospital before and after intervention,evaluate intervention efficacy,and provide evidence for the rational clinical antimicro-bial application.Methods From August 2012,measures were taken to intervene perioperative antimicrobial use, perioperative antimicrobial use and surgical site infection(SSI)in 312 patients undergoing arthroscopic surgery be-tween September 2011 and August 2013 were retrospectively surveyed.Results A total of 312 patients were investi-gated,pre-and post-intervention were 150 and 162 cases respectively,SSI rates were both 0 before and after inter-vention. Antimicrobial usage rate after intervention was lower than before intervention (26.54% vs 100.00% ,χ2=1.781,P<0.001). Irrational antimicrobial use dropped obviously;average expense of antimicrobial agents dropped from (1165.69±756.33)yuan (RMB)before intervention to (32.71 ±119.29)yuan (RMB)after intervention (t= 3.330,P<0.001).Conclusion Perioperative antimicrobial usage rate in arthroscopic surgery at this hospital decreased significantly after intervention,rational use of antimicrobial agents has improved,SSI rate still remains zero.

OBJECTIVE To study the homology of resistant Gram-negative bacteria isolating from the hospitalized patients,hospital environment and hands of medical staffs in intensive care unit(ICU).METHODS To collect and identify 58 clinical resistant Gram-negative bacteria isolates and environment isolates from intensive care units,the same type of Gram-negative bacilli were studied on the homology using plasmid profile,restriction endonuclease profile and enterobacter repetitive intergenic consensus PCR(ERIC-PCR).RESULTS The homology existed between the resistant bacteria of clinical isolates and environment specimens.CONCLUSIONS We found that the multidrug-resistant Gram-negative bacteria derive from a common origin and cause an outbreak in ICU.So medical staff must emphasize the concept of hand hygiene and reinforce the measure of cleaning and sterilization,in order to control nosocomial infection.

Objective To investigate the nationwide prevalence of healthcare-associated infection (HAI),and es-tablish the related indexes of HAI.Methods A cross-sectional survey was conducted through combination of bed-side investigation and medical record reviewing,the prevalence of HAI in hospitals of National HAI Surveillance System and other hospitals voluntarily participated in the survey were investigated according to unified survey pro-gram.Results A total of 1 008 584 patients in 1 766 hospitals participated in the survey,26 972 cases of HAI occurred, prevalence rate of HAI was 2.67%,antimicrobial usage rate was 35.01%.Difference in prevalence rates of HAI and anti-microbial usage rates among hospitals with different number of beds were both significant (χ2 =1 599.21,3 458.40,re-spectively,both P <0.01).The main infection sites were lower respiratory tract (47.53%),urinary tract (11.56%)and surgical site(10.41%).A total of 13 784 pathogenic strains were isolated,the top five pathogens were Pseudomonas aeruginosa ,Escherichia coli ,Klebsiella pneumoniae ,Acinetobacter baumannii ,and Staphylococcus aureus .Prevalence rate of HAI and prophylactic antimicrobial usage rate in patients receiving operation of class Ⅰincision were 1.01% and 27.99% respectively,difference in prophylactic antimicrobial usage rates in patients receiving operation of classⅠincision at hospitals with different number of beds were significant (χ2 =400.34,P <0.01 );among patients receiving antimicrobial prophylaxis,percentage of specimens sending for bacterial detection was 45.89%,difference in bacterial detection rates in hospitals with different number of beds were significant (χ2 =9 189.90,P <0.01).Hospital with more than 900 beds had the highest prevalence rate of HAI(3.36%),lowest usage rate of antimicrobial agents(32.35%),and highest bacterial de-tection rate(56.03%).Conclusion Multiple indexes of this cross-sectional survey revealed that HAI management in China has achieved remarkable results;meanwhile,calculation of the percentile distribution of each index is convenient for self-evaluation for HAI-related work in each hospital.

Objective To realize basic status of occupational exposure among medical postgraduates,and provide theoretical evidence for making occupational precaution measures.Methods Data about occupational exposure among medical postgraduates in a teaching hospital between January 2011 and December 2013 were analyzed retro-spectively.Results A total of 3 362 medical postgraduates were monitored,56 (1 .67%)sustained occupational ex-posure.The most common occupational exposure sites were left hand thumbs(n=15,26.79%),occupational expo-sure most frequently occurred during operation(n=29,51 .79%),a total of 40(71 .43%)occupational exposure oc-curred during the process of operation and invasive procedure,all were sharp injuries.46(82.14%)exposure sources were with bloodborne-transmitted diseases.Surgery students accounted for 66.07%(n =37)of students sustained occupational exposure,exposure rate in master’s candidates was higher than doctoral candidates(2.31 % vs 0.28%,χ2 =18.325,P <0.001 ).After timely treatment and preventive medication,none of the students were infected. Conclusion It is necessary to strengthen the occupational safety education for medical postgraduates,improve pre-caution awareness,standardize all kinds of procedures,and implement standard precaution;timely and effective treatment after exposure is important for reducing occupational injury among medical postgraduates.

OBJECTIVE To study the resistance of plasmid mediated AmpC ?-lactamase in Pseudomonas aeruginosa,to detect and identify the AmpC genotype,and to provide the laboratory evidence for antibiotic reasonable application in clinics.METHODS Totally 108 strains of clinically isolated P.aeruginosa were determined antibiotic-resistant phenotype by K-B disc test,and cefoxitin three dimensional test was applied to screen AmpC positive strains.Plasmids were extracted from AmpC positive strains by SDS-alkali splitting technique.The depurated plasmid was used to amplify AmpC ?-lactamase genes by PCR.Positive PCR product was sequenced by Shanghai Sangon Biological Engineering Technology Company.Gene homology of PCR product with other index sample gene sequences was compared.RESULTS There were 28 strains producing AmpC enzyme among 108 P.aeruginosa strains.AmpC Producing P.areuginosa strains displayed multidrug-resistance to antibiotics and a new P.areuginosa strain producing plasmid mediated CMY-7 type AmpC enzyme was discoverd firstly.CONCLUSIONS Presented plasmid mediated AmpC enzyme and AmpC type ?-lactamases in P.aeruginosa are its important resistant mechanism to antibiotics.A strain producing type CMY-7 plasmid mediated AmpC enzyme is found firstly in China.

OBJECTIVE To study the relation between the occurrence of nosocomial infection(NI) and white blood cell(WBC) count in malignant tumor patients after chemotherapy.METHODS The occurrence of NI and leukopenia and application of granulocyte colony stimulating factor(G-CSF) in patients after chemotherapy from Jan 2003 to Jun 2004 was investigated and analyzed retrospectively.RESULTS Among 2 040 patients,8.87% developed NI,and case rate was 11.67%;among patients with WBC count

0.05). CONCLUSIONS Proper use of disinfectants based on routine cleaning can achieve good results in the nosocomial infection control of the NICU.

Objective To realize the incidence of healthcare-associated infection (HAI),the rate of invasive procedure and related infection rate,use of antimicrobial agents and distribution of pathogens in gereral intensive care units (GICUs) of hospitals in China.Methods HAI cross-sectional investigation data of GICUs reported to China HAI Surveillance Net-work were summarized and analyzed.Results Of 1 313 hospitals,621(47.30%)had GICUs;a total of 5 887 patients were surveyed,1 634 patients developed 1 962 times of infection,HAI prevalence rate and case rate was 27.76% and 33.33%respectively.The main infection sites were lower respiratory tract(70.39%),urinary tract (12.79%)and blood(2.86%). The application rate of urinary catheter,arteriovenous catheter and ventilator was 53.52%(n=3 151),37.05%(n=2 181) and 35.62%(n=2 097)respectively,and related prevalence of urinary tract infection,pneumonia and blood stream infection was 4.67%,20.41%,and 0.60%,respectively,which accounting for 58.57%,30.99%,and 23.21 % of urinary tract infection,pneumonia and blood stream infection respectively,the overall prevalence of above invasive procedure-re-lated infection accounted for 29.97%(588/1 962)of the overall HAI prevalence.A total of 1 795 isolated pathogens causing HAI were detected,the top three were Pseudomonas aeruginosa (20.78%),Acinetobacter baumannii(17.99%)and Klebsiella pneumoniae (11 .64%).The usage rate of antimicrobial agents was 71 .58%(n=4 214), rate of specimens delivered for detection was up to 75.27%(2 553/3 392).Conclusion Prevalence and antimicrobial use in patients in GICUs are all high,all kinds of invasive procedure are frequent,30% of HAI are related to inva-sive procedure;infection caused by non-fermentative bacteria is serious,pathogen detection is well performed.

OBJECTIVE To improve the surveillance and control of hospital infection.METHODS A series of management surveillance network information system for hospital infection were established by using SQL Server 2000 as database and Delphi 7.0 as program tool.The system included hospital infection case surveillance subsystem,antibiotic rational usage subsystem and the interface program of hospital information subsystem.RESULTS The hospital surveillance network connected the hospital infection department with the medical laboratory department and inpatient department,so the hospital infection data could be shared by all departments of hospital.CONCLUSIONS The system can improve work efficiency of hospital infection surveillance.