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Objective:This work aims to investigate the virulence features, spore formation and the resistance mechanisms of major sequence types (STs) of clinical Clostridium difficile isolates from nosocomial infectious diarrhea. Methods:Clostridium difficile isolates were prospectively collected from 816 loose stool samples of in patients with antibiotic associated diarrhea at the Beijing Friendship Hospital of Capital Medical University from September 2017 to September 2019. The main ST types ST81 (26 strains), ST8 (15 strains) and ST42 (14 strains) of C. difficile were used as experimental strains. The polymerase chain reaction (PCR) and enzyme-linked immunoassay (ELISA) were performed to detect toxin genes and toxin production of different C. difficile ST types, respectively. The count of the colony forming units (CFU) of the strains as conducted by using the brain-heart infusion (BHI) agar plates. The antimicrobial resistance patterns of the strains to eleven kinds of antibiotics were determined by agar dilution method. The antimicrobial resistance genes: gyrA, gyrB and ermB were amplified and sequenced from the stains. Mutations in the resistance genes were analyzed by sequencing. Measure data was compared by Kruskal Wallis Test, differences in the resistance rates in three group were compared using Fisher exact test. Results:ST81 strains were identified as the tcdA-tcdB+/ cdtA-cdtB-toxin type, ST8 and ST42 strains belonged to tcdA+tcdB+/ cdtA-cdtB-toxin type. The toxin production of ST42 strains (41.9) were higher than ST8 (2.4) and ST81 groups (0.83) (all P<0.001). The number of spore quantities of ST81, ST8 and ST42 strains were 494×10 5CFU/ml, 160×10 5CFU/ml and 166×10 5CFU/ml, respectively. The spore quantities of ST81 strains were much higher than that of ST81 and ST42 strains (all P<0.001). From the in vitro susceptibility test, 100% (26/26) ST81 strains were featured as multi-drug resistant (MDR), and they were resistant to moxifloxacin, ceftriaxone, erythromycin and clindamycin. The resistance rates of ST8 strain to moxifloxacin, erythromycin and clindamycin were 9/15, 11/15 and 11/15, respectively. ST81 strains had higher resistance rates to moxifloxacin, clindamycin and erythromycin, compared to ST8 strains ( P=0.001, P=0.005 and P=0.005). All ST42 strains were susceptible to ceftriaxone and 3/14 ST42 strains were resistant to moxifloxacin. ST81 strains had higher resistance rates to ceftriaxone and moxifloxacin than the ST42 strains (both P<0.001). The positive rate of ermB in ST81 strains (100%, 26/26) were higher the ST8 strains (11/15) ( P<0.005). Amino acid mutation analysis showed that ST81and ST8 stains had one amino acid substitution in both GyrA and GyrB, but the amino acid substitutions were different in GyrB between two ST types. ST81 strains had two point-mutations: Thr82 replaced by Ile in GyrA, and Asp426 replaced by Val in GyrB. ST8 strains had point-mutation: Thr82 replaced by Ile in GyrA; Asp426 replaced by Asn in GyrB. For ST42 strains, Thr82 was replaced by Ile in GyrA. Conclusions:ST81 and ST42 strains were MDR. ST81 had higher spore ability, whereas ST42 strains had more virulence. ST81 strains and most of ST8 strains had high level of fluoroquinolones resistance. It is important to supervise persistently these three ST genotypes to prevent further dissemination.
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Objective To realize the distribution and characteristics of Mycobacterium leprae (M.leprae) species and its single nucleotide polymorphisms (SNPs) spreading currently in China.Methods A total of 171 cutaneous lesion specimen of leprosy patients from 22 provinces were collected.The 16S rRNA conservative region of Mycobacterium leprae was amplified by nest PCR and the positive products were sequenced directly and aligned by BLAST.The SNPs of M.leprae were genotyped by restricted fragment length polymorphism for the PCR products.Results The 171 specimen were all Mycobacterium leprae since the amplified fragments of DNA samples were 99％ similar to the Br4923 of M.leprae from Brazil.No new species (M.lepromatosis) was found.Among the 85 samples genotyped for SNPs,SNP3,SNP1 and SNP2 accounted for 78.8％ (67/85),20％ (17/85) and 1.2％ (1/85) respectively.There was no sample with SNP4 genotype to be detected.Among the 171 sequencing specimen,130 showed mutation C-T at 251 bp of 16S rRNA.There was no difference for mutant rate of 16S rRNA gene and SNP genotype among the samples with different clinical pathological types.Certain associations between 16S rRNA C251T mutation and SNP genotype were found.Most of the samples with C251T mutations of 16S rRNA sequence were SNP3,only a few were SNP1 but not SNP2.There was significant difference of SNP genotype distribution among the patients from different regions.The distribution rate of SNP3 genotype in the samples from inland region (97.1％,34/35)was significantly higher than that from coastal region (66％,33/50) (x2 =11.96,P ＜ 0.01) . There was significant difference of the gene mutation rate of 16S rRNA sequence among the patients from different regions.The mutation rate of 16S rRNA in the samples from inland region (94.8％,92/97) was significantly higher than that from coastal region (51.4％,38/74) (x2 =43.56,P ＜0.01).Conclusion C251T mutation in 16S rRNA gene sequence of M.leprae may associate with SNP type suggesting that the characteristics of geographical distribution presented in different genotypes of M.leprae.No new species of M.leprae was found in this study.
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Objective To discuss the application of transanal placement of ileus tube in treatment of colonic obstruction in left colorectal cancer.Methods Thirty-two patients with left malignant colorectal obstruction were divided into ordinary colonoscope group (16 cases) and superslim endoscope group (16 cases) by random digits table.The catheter success rate,catheter operating time and exposure to X-ray time was compared between two groups.Results Fifteen cases were successful and 1 case was failed in ordinary colonoscope group.Thirteen cases were successful and 3 cases were failed in superslim endoscope group.There was no significant difference in the catheter success rate between two groups (x2 =1.143,P =0.285).The catheter operating time was (42 + 15),(20 +6) min in ordinary colonoscope group and superslim endoscope group,and there was significant difference between two groups (t =3.895,P =0.005).The exposure to X-ray time was (20 + 12),(5 + 2) min,and there was significant difference between two groups (t =-3.596,P =0.007).Conclusion Transanal placement of ileus tube is more successful and convenient by superslim endoscope combined with anesthesia than by ordinary colonoscope.
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<p><b>OBJECTIVE</b>To research the relationship between the virulence factors of Saccharomyces albicans (S. albicans) and the random amplified polymorphic DNA (RAPD) bands of them, and establish the regression model by multiple regression analysis.</p><p><b>METHODS</b>Extracellular phospholipase, secreted proteinase, ability to generate germ tubes and adhere to oral mucosal cells of 92 strains of S. albicans were measured in vitro; RAPD-polymerase chain reaction (RAPD-PCR) was used to get their bands. Multiple regression for virulence factors of S. albicans and RAPD-PCR bands was established.</p><p><b>RESULTS</b>The extracellular phospholipase activity was associated with 4 RAPD bands: 350, 450, 650 and 1 300 bp (P < 0.05); secreted proteinase activity of S. albicans was associated with 2 bands: 350 and 1 200 bp (P < 0.05); the ability of germ tube produce was associated with 2 bands: 400 and 550 bp (P < 0.05).</p><p><b>CONCLUSION</b>Some RAPD bands will reflect the virulence factors of S. albicans indirectly. These bands would contain some important messages for regulation of S. albicans virulence factors.</p>