Epidemiological Study On Nosocomial Infection

Nosocomial infection(NI) is defined as the infection acquired by all modes oftransmission that occur in hospital, or acquired in hospital but attacked after leavinghospital. It includes the infections transmitted between infected patients, staffmembers, or visitors. However, it doesn't cover the infection that acquired beforeadmitting.Nosocomial Infection Surveillance is essential for hospitals to control NI, and allpreventive or controlling steps of NI must be based on NIS. ComprehensiveSurveillance is to monitors all the patients and hospital staff and all relative effectfactors of NI, which is still used in China mainly now. While a great deal of time andhuman resources are needed during Comprehensive Surveillance, the ChineseNosocomial Infection Surveillance System is still in defect of comprehensiveness,accuracy and standardization.Targeted Surveillance focuses on specific subjects with limited human and materialresource. Some well-conditioned hospitals in China have developed TS about somerisk factors of NI, which provided the groundwork for establishing nationwide andsystemic ST in the near future. There are still many problems in these research suchas more descriptive studies and less analysis studies, more case-control studies and less cohorts studies, less prospective evaluation studies with NI risk factors.Control of NI, especially the exogenous NI, mostly depend upon the degree of howthe hospital population (staff and patients) master the knowledge and skills of NI. So,it is important to develop health education, popularize knowledge of NI, and improvethe hospital population's indepence and intiative for self-prevention.Presently, many kinds of investigations and trainings about NI have been carried outwidely to the medical staff including doctors, nurses and interns in China. Though thepatients are both the main sourse and the main susceptible population of NI, thesekinds of study on patients have not been reported domestically yet, which will lead tothe lack of fundamental data to develope pertinent health education for patientpopulation.PartⅠ. Descriptive study on nosocomial infectionin a hospital during 2000-2006ObjectiveTo analyze the data of NI in a teaching hospital for seven years (from 2000 to 2006)and reveal the distribution and tendency.MethodsInvestigate retrospectively the in-patients' case history during 2000 and 2006.Results1. All 203800 cases were studied, 7104 of which were acquired NI and theincidence was 3.5％, the incidence density was 2.3％. 8239 times attacked, thecase-times incidence was 4.1％. 2. The frequent NI sites are respiratory tract (61.9％), surgical site(6.7％), urinarytract (6.3％)and gastrointestinal tract(6.0％).3. The NI incidence(5.9％)and incidence density(4.5‰) of Age 0-7 are the highest,The NI incidence(2.8％)and incidence density(2.0‰) of Age 25-34 are thelowest, The NI incidenceand incidence density of those older than 75 years old is4.8％and 3.0‰respectively.4. The septicemia incidence(0.6％)(P＜0.001) and incidence density(0.4‰) of Age8-14 are the highest.The gastrointestinal infection incidence(0.5％)(P＜0.001) andincidence density(0.5‰) of Age 0-3 are the highest. The urinary infectionincidence and incidence density rises with the age increasing (P＜0.001).5. The incidence of male(3.7％)is higher than female's(3.2％)(P＜0.001), but boththe incidence density are 2.3‰; The respiratory infection incidence ofmale(2.3％)is higher than female's(1.9％)(P＜0.001), but both the incidencedensity are 1.4‰; The Surgical Site infection(SSI) incidence(0.3％) andincidence density(0.2‰) of male is higher than female's(0.2％)(0.1‰); Theurinary infection incidence(0.3％) and incidence density(0.2‰) of female ishigher than male's(0.2％)(0.1‰).6. The NI incidence and incidence density rises with prolonging of stay; infectedgroup's median of stay length is 30d, the non-infected group's is 10d.7. The NI incidence(4.1％) and incidence density(2.3‰) of operative patients ishigher than non-operative patients' (3.2％)(2.2‰); The respiratory infectionincidence of operative patients(2.3％) is higher than non-operative patients'(2.1％)(P＜0.001), but the respiratory infection incidence density of operativepatients(1.5‰) is higher than non-operative patients' (1.3‰). 8. The NI incidence of hematology department(33.51％), rehabilitationdepartment(14.59％) and neonatal ward(9.52％) are highest; The NI incidencedensity of hematology department(12.47‰), neonatal ward(10.31‰) andpediatric department(6.20‰) are highest.9. The NI fatality of intraperitoneal tissue infection(4.9％) is the highest, secondlythe septicemia fatality(9.5％), thirdly the respiratory infection fatality(5.7％).10. The most commonly identified organisms is gram-negative bacteria includingS.epidermidis, staphylococcus and enterococcus, while gram-positive bacteriaincluding P.aeruginosa, E.coli and Klebsiclla. The drug resistance ratio ofPseudomonas Aeruginosa and Staphylococcus Aureus is increasing.Conclusions1. The incidence density was combined with Chi-test to analysis the NI effect factorsfirstly in China. The more creditable and scientific results obtained.At the sametime, the necessity to use incidence density as the main scale in NI surveillancewas proved.2. The hematology department, rehabilitation department, and neonatal ward are thekey departments for surveillance.To prevent operative patients from infection ismore important in large scale hospitals.3. Group of age above 75yrs or below 7yrs are susceptible populations forrespiratory infection; younger than 3yrs are high risk for gastrointestinal infection;the group of age 8-14 are apt to attack septicemia; the old female is the keysurveillance object for urinary infection. NI of intraperitoneal tissue is the mostdangerous infection type.4. NI incidence and length of stay are the cause and effect for each other. NI incidence increased significantly with the prolongation of length of stay. At thesame time, the occurrence of NI would prolong the length of stay.5. In this study, the pathogens mainly consist of opportunistic bacterium andopportunistic fungi, most of their drug resistance rate is rising.PartⅡThe retrospective cohort study on nosocomial infectionof theⅡincision operative patientsObjectiveTo screen the risk factors of nosocomial infection inⅡincision operative patients.MethodsStudy on all the operative in-patients whose length of stay is above 48h during Jan. toDec. 2006. The initial point of observation is the time of operation beginning, the endpoint of observation is the time of nosocomial infection occurring or the dischargetime.Results1. 227 NI patients have been found, and the NI incidence was 4.6％, the NIincidence density is 6.1‰., 3 cases died.2. Mono-factor analysis result showed, the male's NI incidence(7.5％) was higherthan the female's(2.7％); the patients whose age was between 14 and 60 have thelowest NI incidence(3.7％), the patients older than 60 have the highest NIincidence(11.7％); the patients whose duration of the operation is shorter than 2 hours have the lowest NI incidence (2.3％), if the duration of the operationextends to 2 to 6 hours the NI incidence will increase about 2.5 times higher, if itextends to more than 6 hours the NI incidence will increase about 7 times higher;it will increase the NI incidence significantly if the patients' length of stay weremore than 3 days before the operation; the NI incidence of selectiveoperation(4.4％) is lower than that of emergency operation(6.2％); the NIincidence of the patients of general anesthesia (6.9％) is higher than those of otheranesthesia(2.8％); the NI incidence was decreasing by spring, summer, autumnand winter in order; the NI incidence rose with the kind of invasive operationincreasing, the NI incidence of patients who had received no invasive operationwere 2.2％, the NI incidence of patients who had received 1 invasive operationwere 3.7％, the NI incidence of patients who had received more than 2 invasiveoperations were 6.6％; All the results above was P＜0.05.3. The NI incidence of the patients with antibiotic prophylaxis(4.0％) is lower thanthose without antibiotic prophylaxis (5.3％)(P＜0.05); the patients who used lessthan 2 kinds of drugs have the lower rate(3.7％) than those who used more than 3kinds of drugs(6.6％)(P＜0.05); the impacts of time and course of treatment beforeoperation on NI incidence had no statistical significance(P＞0.05).4. Leading the 8 factors into Cox stepwise regression model analysis: gender, age,length of stay before operation, emergency/selective, duration of operation,seasons, if or not general anesthesia, the kind of invasive operation, everyone of8 factors were independent risk factors.5. The average risk factor index is 1.8, the risk factor index of thoracic surgerydepartment is 3.3, general surgery department is 3.1, neurosurgery department is3.0 and the lowest is gynecology and obstetrics department's (0.9). 6. The orders of NI incidence density changed before and after standardrized by riskfactor index. The incidence density of gynecology and obstetrics department beforstandardrized is eleventh, but it's fifth after standardrized; the incidence density ofthoracic surgery department befor standardrized is fifth, but it's seventh afterstandardrized; the incidence density of general surgery department beforstandardrized is seventh, but it's ninth aider standardrized.Conclusion:1. The result of retrospective cohort study on nosocomial infection of theⅡincisionoperative patients indicated, pneumonia is the main infection type of patients withⅡincision operation. To controle pneumonia can decrease not only the incidenceof NI but also the fatality of NI.2. Gender, age, length of stay before opreation, selective/emergency operation,duration of operation, seasons, if or not general anesthesia, the kind of invasiveoperation were the 8 independent impact factors of NI in operative patients.3. For the first time, the incidence density standardrized by risk factors index wereused to compare the disease intensity between different departments and surgeons,which is more scientific than standardrized incidence.4. At present, most of the clinicians have the consciousness of antibacterialsprophylaxis, but the appropriate time and course should be emphasis. It wasadviced that antibacterials prophylaxis should start 2 hours before operation, stopin 48 hours after operation. PartⅢ. Investigation of Knowledge, Attitude, Practicein Out-patients PopulationObjectiveKnowledge, Attitude, Practice(KAP) about NI and the impact factors wereinvestigated in out-patients population firstly in China, which would provide thenecessary basic information and theory evidence when a suitable health educationproject about NI was made.MethodsOut-patients over 14 years and their accompanies in 11 hospitals in GuangdongProvince and Hunan province of China were surveyed with KAP questionnaire.Results1. Validity and reliability of questionnaireThe KAP questionnaire was designed by the author, and was revised for 3 timesduring trial. Both the face validity and content validity were finally admissive fromspecialists. Intraclass Correlation Coefficients is 0.959～0.997 (P＞0.05) revealing agood test-retest Reliability. The Cronbachαcoefficient of the questionnaire is0.959～0.997, and Cronbach's Alpha Based on Standardized Items is 0.746～0.871revealing 1 a sufficient reliability of uniformity.2. Basic data3850 sheets were issued, and 3563 valid sheets were withdrawn except for 288uncompleted ones, the valid ratio is 92.5％. From 3562 respondents 1941 were maleand 1621 were female. 56.5％of them was age under 30yrs, 11.3％was above 50yrs.The youngest is 14yrs and the eldest is 84yrs, the average age is 32.35yrs. 3. Data of knowledge25.5％of the respondents had never heard about "nosocomial infection"; 22.3％,28.5％and 14.6％did not know the endogenous causes of infection such as "theseverity of disease","the oldness of patients","the length of stay", respectively; 80.3％of the respondents had never been told about NI by staff; 87.2％of the respondentsthought the NI can been avoided if the hospital pay more attention to it.4. Impact factors of knowledgeAnalysis the 6 variables: gender, educational attainments, health education fromprofessional, grade of hospital, length of stay and age in binary forward logisticregression model. The former 4 was the independent impact factors on the knowledgeof NI.5. Data of attitudes and practicesMost of respondents show great concern on NI, but 26.5％would choose a hospitalaccording to its specific incidence rate of NI, and 39.0％would point out theignorance of washing hands of hospital staff.6. Impact of knowledge on the attitudes and practicesWith the increase of awareness, the worry about NI is increasing (P＜0.001), and thedesire to learn the knowledge of NI is stronger (P＜0.001), the behavior habits such aswashing hands, reasonable use of antibiotics is better.However, the less of knowledge, the compliance to do prevention is better (P＜0.001),and the higher of the knowledge, the more tendency to put the duty of infection onhospital (P＜0.05).The Pearson correlation coefficient between knowledge and attitude, practice are r=0.076 and r=0.271, (P＜0.001).Conclusions1. It should be emphasized that the knowledge of NI is need to be elevated in theout-patients population who are elder, lower educational attainment, male andusually visit community hospitals.2. To know the inevitability and the endogenous causes of NI can improve thecompliance and understanding of out-patients.3. The independence and initiative in prevention and control of NI should beadvocated and cultivated. One of its external promoters is the publicity of NIreports.4. The face-to-face healthcare education between hospital staff and patients is veryimportant and effective way, which should become a persistent and long-termmechanism.