Study On Characteristics And Risk Factors Of Clostridium Difficileinfectionin Adults

Background and objectiveClostridium difficile is an anaerobic,spore-forming Gram-positive bacillus.C.difficile-associated infection(CDI)is not only a leading cause of antibiotic-associated diarrhea(10%-25%)but also an important nosocomial infection that causes a spectrum of diseases ranging from mild diarrhea to severe life-threatening pseudomembranous colitis or even death.Since C.difficile BI/NAP1/027 clones have caused large epidemics across US and some Europe with substantial morbidity and mortality,its spread brought the huge challenge for control of CDI.The global epidemiological investigations show epidemiological changes of CDI and its risk factors vary depending on time and geography.However,in China,systematic epidemiological data about CDI is rare,most of them focus on the molecular characteristics of Clostridium difficile.It’s the first time in our hospital to approach Clostridium difficile from different angles,from dynamic monitoring clinical and molecular characteristics to virulence gene,drug resistance and risk factors.It will help us identify better infection control measures and fill gaps in our hospital in this area,simultaneous,add the monitoring data in our country.Part 1 Clinical and molecular characteristics of Clostridium difficile infectionObjective:Our study will have insight into the various dynamics of Clostridium difficile transmission,virulence genes and drug resistance in different departments and time in a teaching hospital,so as to comprehensive understand of Clostridium difficile infection in the teaching hospital.Methods:From June 2014 to August 2015,stool samples of the suspected patients with CDI were inoculated onto C.difficile selective medium CDIF to separate C.difficile strains and then identified by API 20A and MALDI-TOF MS.We monitored bacterial strain clonality by MLST,antimicrobial resistance pattern by agar dilution method and prevalence of toxin genes(tcdA,tcdB,ctdA and ctdB)by conventional PCR.What’s more,we compared clinical characteristics of patients infected with ST81 Clostridium difficile and non ST81 strains to find distinguishing features of the main type ST81 Clostridium difficile strains.Results:Of 798 unformed stool samples,91 C.difficile were cultured.Excluding 11non-toxigenic isolates,there were a total of 80 nonduplicate toxigenic C.difficile strains with 10.0%(80/798)incidence and 17 cases occurred in outpatients.1、According to evolutionary analysis of C.difficile strains,91 C.difficile contained with 26 distinct genotype STs by MLST.The diversity index was 28.6%(26/91).The eBURST algorithm clustered all 26 STs isolated from clinical patients into 7 clone complex(CC).One large cluster of isolates,ST81,was identified corresponding to30.8%of all strains(28/91),followed by ST2(9.9%),ST54(8.8%),and ST129(8.8%).None of the isolates was identified as ST1(RT027)and ST11(RT078)which were the two most common strains in American and Europe.2、Excluding the 11 non-toxigenic strains,tcdA and tcdB genes were both present in the isolates,although 30 of them had a partial deletion in tcdA(A-B+).Most of A-B+strains were classified into ST81(93.3%,28/30)and the remaining two isolates were ST37 which is one allelic atpA variant of ST81.However,no isolates contained binary toxin genes.Of the 80 toxigenic C.difficile strains evaluated,56.3%(45/80)displayed resistance to clindamycin,32.5%(26/80)to moxifloxacin,6.3%(5/80)to tetracycline,and only one strain was resistant to metronidazole.All of the strains were susceptible to the other four drugs vancomycin,chloramphenicol,ampicillin,and meropenem.We categorized the isolates as ST81 isolates and non-ST81 isolates and compared rates of antibiotic resistance in the two groups.Clindamycin resistance in ST81 isolates reached 71.4%compared with 48.1%in non-ST81 isolates(P=0.03),and the frequency of resistance to moxifloxacin was five-fold higher in the large-cluster isolates than in the other isolates(67.9%and 13.5%,respectively,P<0.01).Five ST81 isolates were resistant to tetracycline,however,non-ST81 isolates were all susceptible to tetracycline.3、Different departments were more likely to have different composition of C.difficile genotypes.ST81,ST54,ST2,and ST3 were detected from at least three departments.C.difficile were most detected from gastroenterology department,followed by emergency department and the main strains in this two units were ST81 C.difficile.CDI case numbers showed an increasing trend,peaking in June 2015 due to a special genotype epidemic event,and falling to a pre-epidemic level following this.We found that ST81 isolated from the emergency room contributed greatly to the epidemic event in May and June 2015.We next investigated the spread of 15 C.difficile ST81 isolates during this period,particularly in the emergency department.Of 15 infected patients,eight were from the emergency department,four from the gastroenterology department,two from the nephrology department and one from the cardiology department.Eight patients in the emergency department were all first admitted toemergency department observation room and then to their ward.Five of the remaining seven patients were admitted to emergency department observation room before being moved to other wards.Two gastroenterology department patients did not pass through emergency department observation room but shared hospital stays with two patients from the same unit.Ward-based network analysis showed a high level of transmission within emergency department observation room,so we examined the emergency department observation ward environment in the middle of June 2015,from which two ST81 isolates were isolated from toilets.Ribotyping showed that the17 isolates were the same type.4、25 ST81 strains and 34 non-ST81 strains were used for comparison of clinical characteristics.Patients infected with ST81 isolates were significantly older than those infected with non-ST81 isolates.Mean age of patients with ST81 isolates and other genotypes was 68.4±15.7 years and 47.0±21.2 years respectively(P<0.01).Of patients with ST81,60.0%were older than 65 years compared with 20.6%of non-ST81 patients.Charlson Comorbity Index was higher in patients with C.difficile ST81 infection than in those infected with non-ST81 isolates(2.8±2.1 vs.0.7±1.0).Of patients with ST81 infection,48.0%had more than three comorbidities compared with2.9%of patients with non-ST81 infection.There were no significant differences in gender,period of hospitalization,PPI use,numbers and categories of antibiotics used.For cases diagnosed with severe diarrhea,we compared fever,hypoalbuminemia(<20g/L),WBC count(>12×10~9 cells/L),fecal occult blood,presence of fecal erythrocytes,and leukocytes for the ST81 and non-ST81 groups.Fever,serum albumin(<20 g/L),WBC count(>12×10~9 cells/L)were not different between the two groups.However,the non-ST81 group had a higher rate of fecal occult blood and fecal leukocytes than the ST81 group(24.7%vs.4%,p=0.03 and 47.1%vs.8%,p<0.01,respectively).Conclusions:Our study found that an outbreak of ST81 C.difficile with the center of the emergency department observation room occurred during May and June 2015.ST81 C.difficile was not only the most common strains but also detected from a majority of departments in our hospital.Compared with non-ST81 genotypes,ST81had a much higher resistance rate to clindamycin,moxifloxacin and tetracycline.Patients infected with ST81 strains were significantly older and had more comorbidities than those infected with non-ST81 strains,however,clinical symptoms were less serious in patients infected with ST81 isolates than those with non-ST81infection.Continuous surveillance is warranted to reveal insight into the dynamics of ST81 transmission among hospitalized patients generally.All genotypes,especially hypervirulent strains(RT027 and RT078)should be closely monitored.Part 2 Risk factors for C.difficile infectionObjective: A retrospective study was done to analyze the risk factors of CDI so as to avoid these risk factors by early intervention and reduce the infection rate of C.difficile.Methods: We performed a 1:2 case-control analysis with two non-CDI controls randomly selected for each case of CDI in the same inpatient care unit and period of hospitalization during the period from June 2014 to August 2015.Excluding of ineligible patients,59 CDI cases were matched with 118 controls.Demographic clinical variables were compared between the two groups so as to find potential risk factors for CDI.Results: Compared with CDI group and control group,There were no different in gender,comorbidities,clinical symptoms and laboratory examination,however,inpatients infected with CDI would extend hospitalization time(26.1±21.2 vs 20.8±12.6,p=0.03).The results of univariate analysis showed that patients acquiring CDI were more likely to have days of cephalosporins antibiotics(OR 3.69,95%CI 1.22-11.11,P=0.03),hospitalization in the previous 6 months(OR 1.52,95%CI 1.09-2.14,P=0.02),cytotoxic chemotherapy in the previous 6 weeks(OR 2.78,95%CI 1.31-5.87,P=0.01).The following multivariate analysis regression suggested that days of cephalosporins antibiotics is the only risk factor for CDI(OR 5.86,95%CI 1.43-24.02,P=0.01).However,gender,relevantcomorbidities,PPI use,glucocorticoid drugs,hypoalbuminemia(<20 g/L)and WBC count(>12×109 cells/L)were not associated with higher risk of CDI.Conclusions:Patients infected with CDI at the time of hospitalization would prolong hospitalization.Days of cephalosporins antibiotics is the risk factor for CDI,as the use time extended,patients would have more risk for CDI.