BACKGROUND: We evaluated multiplex PCR for species identification and toxin typing to improve the sensitivity and turnaround time of toxigenic Clostridium difficile culture (TCDC). METHODS: We performed multiplex PCR using primers targeting the species-specific gene, tpi, and the toxin genes, tcdA and tcdB. From January to March 2008, 528 stool specimens were tested with direct toxin assay (DT) using C. difficile Tox A/B II (Techlab, Blacksburg, USA) and TCDC. For 288 specimens from early study period, toxin production by C. difficile isolates of TCDC was measured by enzyme immunoassay with culture supernatants using VIDAS C. difficile Toxin A&B (CDAB;bioMerieux, Marcy-l'Etoile, France) and multiplex PCR with isolated colonies. For 240 specimens from late period, only multiplex PCR was used to test toxin production by the isolates. RESULTS: During the early period, 29 C. difficile were isolated and their toxin-positive rates were 65.5% by PCR and 44.8% by CDAB (P<0.05). Among 528 stool specimens, the results of DT+/TCDC+, DT+/ TCDC-, and DT-/TCDC+ were 32 (6.1%), 33 (6.3%), and 10 (1.9%), respectively, when tested with PCR. 13.3% of total 75 positive specimens was detected only by TCDC. Of the 42 toxigenic C. difficile isolates, all were positive for tpi, 30 (71.4%) were tcdA+/tcdB+, and 12 (28.6%) were tcdA-/tcdB+. CONCLUSION: TCDC using multiplex PCR for species identification and toxin typing is sensitive and rapid to be used as a routine diagnostic test.
Boron Compounds ; Clostridium ; Clostridium difficile ; Diagnostic Tests, Routine ; Immunoenzyme Techniques ; Multiplex Polymerase Chain Reaction ; Polymerase Chain Reaction

ObjectiveTo investigate the protective effect of Zhuangtongyin on the Middle Cerebral Artery Occlusion （MCAO） model by modulating ferroptosis through the Nrf2-SCL7A11/xCT-Gpx4 pathway and its underlying mechanism. MethodsC57BL/6J mice were randomly divided into Sham operation group （Sham）， model group （MCAO）， low-dose Zhuangtongyin group （ZTY-L）， high-dose Zhuangtongyin group（ZTY-H）， with 5 mice in each group. The MCAO group was modelled by silica gel embolization， the middle cerebral artery of mice was embolized for 1h， then the silica gel was pulled out and reperfusion was performed after 72 h； and the other operations in the Sham group were the same as those in the MCAO group except that the thread plug was not inserted. The neural function of mice was evaluated by Zea-Longa method. TTC staining was used to evaluate the volume of cerebral infarction. The level of brain injury was evaluated by HE staining and Nissl staining. Prussian blue staining and the expression of iron transport-related carrier receptors TfR1 and DMT1 on mRNA level was detected by qPCR to evaluate the iron ion deposition level in mice brain. The expression of lipid peroxidation-related gene ACSL4 on mRNA level was detected by qPCR， and the content of 4-HNE was detected by ELISA kit to evaluate the lipid peroxidation level of mice brain. The expressions of ferroptosis marker PTGS2 mRNA level was detected by qPCR. The expressions of Nrf2， SCL7A11/xCT， Gpx4 in mice brain tissue were detected by Western-blot and immunofluorescence. ResultsZhuangtongyin improved the nerve function of mice after MCAO （P＜0.05） and the cerebral infarction volume of mice （P＜0.05） and alleviate the pathological injury of cerebral cortex cells after MCAO operation. Zhuangtongyin attenuated the accumulation of trivalent iron ions in the brain tissue of mice following MCAO. Additionally， Zhuangtongyin downregulated the expression of TfR1 and DMT1 mRNA （P＜0.001）， a transporter associated with cellular iron ion uptake， in the brains of post-MCAO mice. Furthermore， Zhuangtongyin reduced levels of lipid peroxidation product 4-HNE （P＜0.001） and suppressed ACSL4 mRNA expression in brain tissue post-MCAO （P＜0.001）. Besides， Zhuangtongyin downregulated the expression of PTGS2 mRNA （P＜0.001）， in the brains of post-MCAO mice. Zhuangtongyin increased the expression of nrf2 into the nucleus （P＜0.001）， and increased the expression of xCT and Gpx4 in neurons after MCAO （P＜0.001）. ConclusionZhuangtongyin can enhance the nerve function and reduce cerebral infarction volume in MCAO/R mice， alleviate the pathological damage of cerebral cortex cells， and modulate the expression of key signaling molecules in the Nrf2-SCL7A11/xCT-Gpx4 pathway. Therefore， it is suggested that the mechanism by which Zhuangtongyin improves MCAO/R injury in mice may involve regulating ferroptosis through the Nrf2-SCL7A11/xCT-GPX4 pathway.