ObjectiveTo establish a high-performance liquid chromatography（HPLC） for the quantitative analysis of multiple components in Gegen Qinlian tablets， and to comprehensively evaluate the quality of samples from different manufacturers by integrating chemical pattern recognition and technique for order preference by similarity to ideal solution（TOPSIS）， in order to provide a reference basis for quality evaluation and control of Gegen Qinlian tablets. MethodsHPLC was employed to determine the contents of 10 components in 28 batches of Gegen Qinlian tablets collected from 6 manufacturers， and taking the detection results as variables， SIMCA 14.1 and SPSS 26.0 were employed for cluster analysis（CA）， principal component analysis（PCA）， and orthogonal partial least squares-discriminant analysis（OPLS-DA） to identify key components affecting the quality. Then， TOPSIS analysis was employed to rank the quality of Gegen Qinlian tablets from the 6 manufacturers and establish a comprehensive quality evaluation method. ResultsA quantitative method for Gegen Qinlian tablets was established. After methodological validation， the method was found to be stable and reliable， and could be used for the quantitative analysis of this preparation. The contents of 3′-hydroxy puerarin， puerarin， 3′-methoxy puerarin， daidzein， coptisine hydrochloride， epiberberine， jatrorrhizine hydrochloride， berberine hydrochloride， palmatine hydrochloride and baicalin in 28 batches of samples were 3.58-7.35， 24.88-42.32， 4.20-9.36， 4.33-7.60， 2.52-6.44， 0.93-4.10， 0.58-3.05， 10.68-22.92， 0.82-4.82， 11.73-60.16 mg·g^-1， respectively. Among them， puerarin， berberine hydrochloride and baicalin all met the limit requirements for this preparation specified in the 2025 edition of the Pharmacopoeia of the People's Republic of China. CA and PCA clustered the 28 batches of samples into 5 categories， PCA extracted 2 principal components with a cumulative variance contribution rate of 90.588%， and OPLS-DA screened out 4 differential markers with variable importance in the projection（VIP） values>1.0， namely baicalin， 3′-hydroxy puerarin， coptisine hydrochloride and palmatine hydrochloride， which might be the main components affecting the quality of Gegen Qinlian tablets. TOPSIS analysis showed that the comprehensive score of each evaluation index（C_i） values of different manufacturers were different. Among them， the C_i of manufacturer B was ranked higher， indicating potentially superior quality， while the C_i of manufacturer A was ranked lower， suggesting potentially inferior quality. ConclusionThis study establishes a quantitative method for Gegen Qinlian tablets， and the content uniformity of the same manufacturer is good， while there are differences in the contents of active components among different manufacturers. Through the chemical pattern recognition analysis， it is found that the content differences of Gegen Qinlian tablets may be related to baicalin， 3′-hydroxy puerarin， coptisine hydrochloride and palmatine hydrochloride.

The problems caused by proximal contact loss(PCL)of dental implants have been a mainstream research topic in recent years,and scholars are unanimously committed to analyzing their causes and related factors,aiming to identify solutions to the problems related to PCL.The effects of the anterior component of force(ACF),the lifelong re-molding of the adult craniofacial jaw and alveolar socket,and the osseointegration characteristics of dental implants are the main causes of PCL.On the one hand,the closing movement of the mandible causes the ACF of the tooth to move through the posterior molar cusp.Moreover,drifting between the upper and lower posterior teeth and mandibular anteri-or teeth can cause the anterior teeth of the upper and lower jaws to be displaced labially.On the other hand,reconstruc-tion of the jaw,alveolar socket and tooth root,the forward horizontal force of the masticatory muscles,the dynamic com-ponent of the jaw and the forward force generated by the oblique plane of the tooth cusp can cause the natural tooth to experience near-middle drift.Additionally,natural teeth can shift horizontally and vertically and rotate to accommodate remodeling of the stomatognathic system and maintain oral function.Nevertheless,the lack of a natural periodontal mem-brane during implant osseointegration,the lack of a physiological basis for near-medium drift,the small average degree of vertical motion and the integrated silence of dental implants without the overall drift characteristics of natural teeth increases the probability of PCL.The high incidence of PCL is clearly associated with the duration of prosthesis delivery and the mesial position;but it is also affected by the magnitude of the bite force,occlusion,the adjacent teeth,restora-tion design,implant location,jaw,and patient age and sex.PCL has shown a significant correlation with food impaction,but not a one-to-one correspondence,and did not meet the necessary and sufficient conditions.PCL is also associated with peri-implant lesions as well as dental caries.PCL prevention included informed consent,regular examinations,se-lection of retention options,point of contact enhancement,occlusal splints,and the application of multipurpose digital crowns.Management of the PCL includes adjacent contact point additions,orthodontic traction,and occlusal adjust-ment.Existing methods can solve the problem of food impaction in the short term with comprehensive intervention to seek stable,long-term effects.Symmetric and balanced considerations will expand the treatment of issues caused by PCL.

Objective:To analyze the effectiveness and interobserver agreement of the Parer five-tier, the National Institute of Child Health and Human Development (NICHD) three-tier, and the International Federation of Gynecology and Obstetrics (FIGO) three-tier electronic fetal monitoring (EFM) systems in identification of neonatal acidosis during labor.Methods:This retrospective study was conducted on full-term singleton cephalic deliveries with neonatal acidosis (umbilical artery blood gas pH≤7.1) and normal newborns (umbilical artery blood gas pH≥7.2) in the Nanjing Drum Tower Hospital, Nanjing University Medical School from January to December 2020. EFM tracings during the last 30-60 min before delivery were collected. Four obstetricians independently described the features of randomly sorted and coded EFM tracings. Another obstetrician categorized these tracings using the NICHD three-tier, FIGO three-tier, and Parer five-tier evaluation systems based on the features. All researchers were masked to the clinical characteristics and maternal and neonatal outcomes. The sensitivity and specificity for identifying neonatal acidosis, as well as the interobserver agreement, were analyzed for all three systems. Independent sample t-test, Chi-square (or Fisher's exact test) and Mann-Whitney U tests were used for statistical analysis. Inter-group comparisons of sensitivity and specificity between the three evaluation systems were assessed using McNemar's test. The Kappa statistic was used to analyze interobserver agreement. Results:This study included a total of 3 558 cases. After propensity score matching, there were 44 cases of neonatal acidosis and 78 control cases. There were no significant differences in parity, gestational weeks, modes of delivery, placental abruption, or analgesia rates between the two groups. The rates of instrumental vaginal delivery and neonatal intensive care unit (NICU) admission in the acidosis group were significantly higher than those in the control group [15.8% (7/44) vs. 2.6% (2/78), χ2=8.45, P=0.003; 31.8% (14/44) vs. 12.8% (10/78), χ2=8.45, P=0.004], while the umbilical artery blood pH and mean base excess were lower in the acidosis group than in the control group [7.04±0.07 vs. 7.30±0.05, t=4.98; (－12.40±3.32) vs. (－5.64±1.95) mmol/L, t=13.61; both P<0.001]. (2) Using the NICHD three-tier system, 95.5% (42/44) of the acidosis cases and 89.7% (70/78) of the control cases were classified as having category Ⅱ EFM tracings, indicating potential fetal acid-base imbalance; category Ⅲ EFM tracings were only observed in 4.5% (2/44) of the cases in the acidosis group. With the FIGO three-tier system, 81.8% (36/44) of the acidosis cases were categorized as having "pathological" tracings, and with the Parer five-tier system, 86.4% (38/44) of the acidosis cases were correctly classified into the "orange or red" risk zones that indicated acid-base imbalance. Among the control cases, there were 28.2% (22/78) with EFM tracings of "normal patterns" categorized by the FIGO three-tier system, and 41.0% (32/78) classified into the "green or blue" risk zones by the Parer five-tier system, which indicated good fetal conditions. None of the acidosis cases were misdiagnosed as being normal by the Parer five-tier system. (3) Compared with the NICHD three-tier system, both the FIGO three-tier and the Parer five-tier systems showed increased diagnostic sensitivity [4.5% (1.2%- 14.5%) vs. 81.8% (66.8%-89.4%) and 86.4% (71.8%-92.4%)], but decreased specificity [100.0% (95.3%- 100.0%) vs. 87.2% (78.0%-92.9%) and 84.6% (75.0%-91.0%)]. There was no statistically significant difference in the sensitivity or specificity between the FIGO three-tier and Parer five-tier systems for identifying neonatal acidosis ( P=0.727 and 0.791). (4) When reading the tracings of control cases, the total agreement rate for the NICHD three-tier system by different observers was as high as 94.2%, while the total agreement rates for the FIGO three-tier and Parer five-tier systems were 69.7% and 67.7%, respectively. In the interpretation of EFHR tracings for acidosis cases, the interobserver agreement for the Parer five-tier system was excellent [Kappa (95% CI): 0.87 (0.79-0.95)], while both the NICHD three-tier and FIGO three-tier systems showed good agreement [Kappa (95% CI): 0.77 (0.66-0.88) and 0.72 (0.60-0.84)]. Conclusions:The Parer five-tier and the FIGO three-tier systems have higher sensitivity in identifying neonatal acidosis than the NICHD three-tier system, and the Parer five-tier system achieves a higher negative predictive value and a greater agreement in the interpretation of pathological EFM patterns.

Objective:To investigate the effects of matrine on proliferation, apoptosis and radiotherapy sensitivity of uveal melanoma cells.Methods:An animal experiment study. In vitro experiment: MuM2B cells of human choroidal melanoma were randomly divided into control group and matrine 0.25, 0.50, 1.00, 2.00 g/L groups. The cell morphology was observed by transmission electron microscope. Cell proliferation was detected by thiazole blue colorimetry. The mRNA and relative expression levels of CyclinD D (CyclinD), B lymphoblastoma-2 (Bcl-2) and Bcl2-associated X protein (Bax) were detected by real-time polymerase chain reaction and Western blot. In vivo experiment: BALB/C mice were injected with MuM2B cell suspension subcutaneously on the back of forelimb to prepare transplanted tumor model. After successful modeling, they were randomly divided into blank group and matrine treatment group with different concentrations. Mice in blank group were injected with phosphate buffer subcutaneously. Mice in different matrine treatment groups were injected with 15, 25, 50, 100 mg/kg matrine subcutaneously, respectively, for 7 consecutive days. The tumor was weighed and its volume was measured after the last administration. Single factor analysis of variance was used to compare different groups. The t test was used for pairwise comparison between groups. Results:In the control group, the cell structure was normal, the distribution was uniform, and no or rare nuclear pyknosis was seen. With the increase of matrine dosage, the nuclear pyretosis increased gradually and cell morphology changed obviously. Compared with the control group, the cell survival rate in 0.50, 1.00 and 2.00 g/L groups gradually decreased with matrine concentration increasing and treatment time prolongating, the relative expression levels of CyclinD and Bcl-2 mRNA and protein gradually decreased, and the relative expression levels of Bax mRNA and protein gradually increased. Under the same radiation dose X-ray irradiation, the cell survival rate of 0.50, 1.00 and 2.00 g/L groups gradually decreased, and the differences were statistically significant ( P<0.05). Compared with blank group, the tumor weight and volume of mice in different doses of matrine group were significantly decreased, and the differences were statistically significant ( P<0.05). Conclusion:Matrine can down-regulate the expression of CyclinD and Bcl-2, up-regulate the expression of Bax, promote the apoptosis of MuM2B human melanoma cells, inhibit cell proliferation, and enhance cell radiosensitivity.

Objective:To compare the clinical efficacy of lateral-rectus approach and ilioinguinal approach in the treatment of Torode-Zieg type IV pelvic fracture in toddlers.Methods:A retrospective cohort study was used to analyze the clinical data of 12 toddlers with Torode-Zieg type IV pelvic fracture admitted to Affiliated Hospital of Youjiang Medical College for Nationalities and Third Affiliated Hospital of Southern Medical University from June 2012 to June 2019. There were 6 males and 6 females, aged 13-36 months [(23.9±7.4)months]. Treatment via ilioinguinal approach was performed for 5 patients (ilioinguinal group), and via lateral-rectus approach for 7 patients (lateral-rectus group). Operation duration, intraoperative blood loss and postoperative complications were compared between the two groups. At the last follow-up, pelvic function was evaluated by Majeed function score, and fracture reduction was evaluated according to Mears-Velyvis radiological evaluation criterion.Results:All patients were followed for 24-72 months [(46.0±18.5)months]. In ilioinguinal group and lateral-rectus group, the operation time was (295.0±95.3)minutes and (165.1±52.2)minutes, respectively ( P<0.05), and the intraoperative blood loss was (190.0±65.2)ml and (225.7±92.0)ml, respectively ( P>0.05). In ilioinguinal group, the development of bilateral iliac wings was asymmetric in 3 patients. In lateral-rectus group, fracture-dislocation of epiphyseal plate together with abnormal development of iliac wing occurred in 1 patient, but had no effects on the function of lower limbs. According to Majeed function score at the last follow-up, the pelvic function in ilioinguinal approach group was rated as excellent in 1 patient, good in 2, fair in 1 and poor in 1, with the excellent and good rate of 60%, while the pelvic function in lateral-rectus group was excellent in 4 patients, good in 1, fair in 2 and poor in none, with the excellent and good rate of 71% ( P>0.05). According to Mears-Velyvis radiological evaluation criterion at the last follow-up, the fracture reduction in ilioinguinal group was rated as satisfied in 3 patients and dissatisfied in 2 patients, with the satisfaction rate of 60%, while the fracture reduction in lateral-rectus group was satisfied in 7 patients and dissatisfied in none, with the satisfaction rate of 100% ( P>0.05). Conclusions:For Torode-Zieg type IV pelvic fracture in toddles, both surgical approaches can complete the reduction and fixation. However, the lateral-rectus approach has shorter operation time and less damage to the epiphyseal structure around the pelvis than the ilioinguinal approach.

Objective:To investigate the diagnosis and treatment for intra-abdominal fistula in China, and to explore the prognostic factors.Methods:A multi-center cross-sectional study was conducted based on the Registration System of Chinese Gastrointestinal Fistula and Intra-Abdominal Infections to collect the clinical data of patients with intra-abdominal fistula from 18 medical centers from January 1, 2018 to December 31, 2018, including basic information, medical records and prognosis.Results:A total of 106 patients were enrolled in this study, including 57 males and 49 females, with an average age of (48.0±17.8)years. The most common type of intra-abdominal fistula was entero-vesical fistula (34.0%), followed by entero-vaginal fistula (31.1%), entero-enteric fistula (26.4%) and multiple fistula (8.5%). The direct causes of intra-abdominal fistula were mainly surgical operation (66.0%), followed by spontaneous fistula due to Crohn′s disease (18.9%), radiation intestinal injury (11.3%), and 4 cases (3.8%) of unknown reasons. During the whole treatment, 95 patients received nutritional support therapy, mainly EN+ PN (75.8%). Finally, 86 patients (81.1%) received surgical treatment, with a healing rate of 95.3%. After surgery, 8.1% of patients developed surgical site infections (SSI), and 10.5% had a relapse of fistula. 20 patients (18.9%) were treated conservatively, with a self-healing rate of 80.0%. The overall mortality rate was 8.5%, and the highest mortality (15.2%) was found in entero-enteric fistula. Statistical analysis showed that the age ( t=-4.664, P<0.001), leucocyte level ( U=663.000, P=0.010), sepsis ( P=0.002) and multiple organ dysfunction syndrome (MODS) ( P=0.019) were higher in the death group than those in the healing group. Multivariate analysis suggested that advanced age ( OR=1.073, 95% CI: 1.008-1.141, P=0.026) and complications of sepsis ( OR=11.806, 95% CI: 1.064-131.048, P=0.044) were independent risk factors of the death for patients with intra-abdominal fistula. Conclusions:The overall mortality rate of intra-abdominal fistula is still high, and malignant tumor is the most common primary disease. Advanced age and sepsis are independent risk factors for death in patients with intra-abdominal fistula.

Objective: To investigate the diagnosis and treatment for enterocutaneous fistula (ECF) in China, and to explore the prognostic factors of ECF. Methods: A multi-center cross-sectional study was conducted based on the Registration System of Chinese Gastrointestinal Fistula and Intra-Abdominal Infections to collect the clinical data of ECF patients from 54 medical centers in 22 provinces/municipalities from January 1, 2018 to December 31, 2018. The clinical data included patient gender, age, length of hospital stay, intensive care unit (ICU) admission, underlying diseases, primary diseases, direct causes of ECF, location and type of ECF, complications, treatment and outcomes. All medical records were carefully filled in by the attending physicians, and then re-examined by more than two specialists. The diagnosis of ECF was based on the clinical manifestations, laboratory/imaging findings and intraoperative exploration. Results: A total of 1521 patients with ECF were enrolled, including 1099 males and 422 females, with a median age of 55 years. The top three primary diseases of ECF were malignant tumors in 626 cases (41.2%, including 540 gastrointestinal tumors, accounting for 86.3% of malignant tumors), gastrointestinal ulcers and perforations in 202 cases (13.3%), and trauma in 157 cases (10.3%). The direct causes of ECF were mainly surgical operation in 1194 cases (78.5%), followed by trauma in 156 (10.3%), spontaneous fistula due to Crohn′s disease in 92 (6.0%), radiation intestinal injury in 41 (2.7%), severe pancreatitis in 20 (1.3%), endoscopic treatment in 13 (0.9%) and 5 cases (0.3%) of unknown reasons. All the patients were divided into three groups: 1350 cases (88.7%) with simple ECF, 150 (9.9%) with multiple ECF, and 21 (1.4%) with combined internal fistula. Among the patients with simple ECF, 438 cases (28.8%) were jejuno-ileal fistula, 313 (20.6%) colon fistula, 170 (11.2%) rectal fistula, 111 (7.3%) duodenal fistula, 76 (5.0%) ileocecal fistula, 65 (4.3%) ileocolic anastomotic fistula, 55 (3.6%) duodenal stump fistula, 36 (2.4%) gastrointestinal anastomotic fistula, 36 (2.4%) esophagogastric/esophagojejunal anastomotic fistula, 29 (1.9%) gastric fistula and 21 (1.4%) cholangiopancreatiointestinal. Among all the simple ECF patients, 991 were tubular fistula and 359 were labial fistula. A total of 1146 patients finished the treatment, of whom 1061 (92.6%) were healed (586 by surgery and 475 self-healing) and 85 (7.4%) died. A total of 1043 patients (91.0%) received nutritional support therapy, and 77 (6.7%) received fistuloclysis. Infectious source control procedures were applied to 1042 patients, including 711 (62.0%) with active lavage and drainage and 331 (28.9%) with passive drainage. Among them, 841 patients (73.4%) underwent minimally invasive procedures of infectious source control (replacement of drainage tube through sinus tract, puncture drainage, etc.), 201 (17.5%) underwent laparotomy drainage, while 104 (9.1%) did not undergo any drainage measures. A total of 610 patients (53.2%) received definitive operation, 24 patients died within postoperative 30-day with mortality of 3.9% (24/610), 69 (11.3%) developed surgical site infection (SSI), and 24 (3.9%) had a relapse of fistula. The highest cure rate was achieved in ileocecal fistula (100%), followed by rectal fistula (96.2%, 128/133) and duodenal stump fistula (95.7%,44/46). The highest mortality was found in combined internal fistula (3/12) and no death in ileocecal fistula. Univariate prognostic analysis showed that primary diseases as Crohn′s disease (χ²=6.570, P=0.010) and appendicitis/appendiceal abscess (P=0.012), intestinal fistula combining with internal fistula (χ²=5.460, P=0.019), multiple ECF (χ²=7.135, P=0.008), esophagogastric / esophagojejunal anastomotic fistula (χ²=9.501, P=0.002), ECF at ileocecal junction (P=0.012), non-drainage/passive drainage before the diagnosis of intestinal fistula (χ²=9.688, P=0.008), non-drainage/passive drainage after the diagnosis of intestinal fistula (χ²=9.711, P=0.008), complicating with multiple organ dysfunction syndrome (MODS) (χ²=179.699, P<0.001), sepsis (χ²=211.851, P<0.001), hemorrhage (χ²=85.300, P<0.001), pulmonary infection (χ²=60.096, P<0.001), catheter-associated infection (χ²=10.617, P=0.001) and malnutrition (χ²=21.199, P<0.001) were associated with mortality. Multivariate prognostic analysis cofirmed that sepsis (OR=7.103, 95%CI:3.694-13.657, P<0.001), complicating with MODS (OR=5.018, 95%CI:2.170-11.604, P<0.001), and hemorrhage (OR=4.703, 95%CI: 2.300-9.618, P<0.001) were independent risk factors of the death for ECF patients. Meanwhile, active lavage and drainage after the definite ECF diagnosis was the protective factor (OR=0.223, 95%CI: 0.067-0.745, P=0.015). Conclusions The overall mortality of ECF is still high. Surgical operation is the most common cause of ECF. Complications e.g. sepsis, MODS, hemorrhage, and catheter-associated infection, are the main causes of death. Active lavage and drainage is important to improve the prognosis of ECF.

Objective To investigate the variation characteristics of peripheral platelet parameters in children with dengue fever and to assess their use and value in diagnosis,prognosis and treatment for dengue fever.Methods Platelet parameters of 69 pediatric patients with dengue fever in acute febrile phase and remission period and 103 healthy controls were compared.The difference of platelet parameters between the liver function injury group and the normal liver function group,the coagulation dysfunction group and the coagulation function normal group,the severe group and the mild group with dengue fever was compared,the causes of thrombocytopenia in children with dengue was investigated so as to better understand the situation of bone marrow producing platelets.Results P-LCR,PDW,MPV were significantly higher in patients in acute febrile phase of dengue fever,compared with the healthy subjects(P＜0.01),while PCT,PLT were significantly lower in patients in acute febrile phase of dengue fever,compared with the healthy subjects(P＜0.01).MPV was significantly lower in patients with abnormal hepatic function when compared with patients with normal hepatic function(P＜0.05),while other platelet parameters did not show significant differences(P＞0.05).PLT and PCT were significantly lower in the severe patients than those in the mild patients(P＜0.05),while other platelet parameters did not show significant differences(P＞0.05).Peripheral platelet parameters did not show significant differences between patients with or without abnormal coagulation function (P＞0.05).Conclusion Peripheral platelet parameters may play a role in the diagnosis,treatment and prognosis of dengue fever in children.

Objective To observe and analyze the change state of serum inflammatory mediators of patients with secondary septic shock after chemotherapy for acute leukemia .Methods 56 patients with secondary septic shock after chemotherapy for acute leukemiawere were selected as the group A,56 patients without secondary septic shock after chemotherapy for acute leukemia were selected as the group B ,56 healthy persons of the same age were selected as the group C,then the serum inflammatory mediators levels of three groups were detected and compared,and the serum indexes of group A with different severity degree of shock were compared, then the detection results of group A and group B with different types ( lymphocytic leukemia and nonlymphocytic leukemia)were compared.Results The serum inflammatory mediators levels, including TNF-α, IL-4, IL-6, IL-10 and other inflammatory factors, including PGE2 , sICAM-1, sVCAM-1 and sCD44, there were group A >group B >group C, severe shock >moderate shock>mild shock ( all P<0.05 ) .The above serum inflammatory mediators and other inflammatory factors levels of different types in group A were higher than those in group B, and the above mediators in lymphocytic leukemia of group A and group B were higher than those in nonlymphocytic leukemia (all P<0.05).Conclusion The serum inflammatory mediators of patients with secondary septic shock after chemotherapy for acute leukemia show higher expression state,and the influence of shock degree and leukemia types for the expression are great.

Objective To investigate the carrying status and characteristics of Clostridium difficile isolated from infants.Methods Two hundred and thirty-eight stool specimens were collected from infant younger than 1 year old,that were hospitalized or outpatient from August to November 2015.Immunochromatography targeted GDH and toxin A&B of C.difficile was used for C.difficile screening,and those positive specimens were inoculated in CDIF and anaerobic culture.C.difficile isolates were genotyped by using slpA sequence typing (slpA ST),and tcdA,tcdB,cdtA and cdtB of C.difficile isolates were detected by PCR.Results Fifty C.difficile strains were isolated from 238 stool samples,and the isolated rates of C.difficile from <3 months,3 months to <6 months,and 6 months to 1 years old groups were 9.3%,17.6% and 27.3%(χ2=6.940,P=0.031<0.05),respectively.52.0%(26/50) of the C.difficile isolates were toxigenic,and 69.2% (18/26) toxigenic isolates harbored tcdA+tcdB+cdtA-cdtB-.Fifty C.difficile isolates were genotyped as 11 slpA STs,slpA ST fr-02 and kr-02 were the commonest genotypes in toxigenic C.difficile isolates;however,that was slpA ST xr-03 in non-toxigenic isolates.Conclusion High C.difficile carriage is found in infants younger than 1 year old,and more than half of C.difficile isolates are toxigenic.Most of toxigenic isolates harbored toxin A and B.The genotype of C.difficile isolates is different between toxigenic isolates and non-toxigenic isolates.