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Objective To understand the circulation,drug resistance and molecular characteristics of Salmonella 1,4,[5],12:i:-in human in Guangdong province.Methods Salmonella 1,4,[5],12:i:-isolated from diarrhea patients in Guangdong during 2007-2016 were detected for drug resistance,genes and PFGE characteristics.Results A total of 2 960 strains Salmonella 1,4,[5],12:i:-were isolated from human diarrhea cases during this period.The positive rates of the isolation increased year by year.The male to female ratio of the infection cases was 1.58 ∶ 1,and the infection mainly occurred in infants and young children.Except imipenem,Salmonella 1,4,[5],12:i:-was resistant to other 17 antibiotics to some extent.The drug resistant rates to ceftazidime,cefotaxime and ciprofloxacin increased from 2011 to 2016.Multi-drug resistance was serious,for example,the multi-drug resistant strains with ASSuT accounted for 70.62％ (435/616) and the multi-drug resistant strains with ACSuGSTTm accounted for 27.11％ (167/616).The lack offljA,fljB and hin genes,as well as the retaining of iroB,STM2740,STM2757 genes,resulted in the unable expression of FljBenx gene with 8 different defection profiles.There were 934 different PFGE patterns observed in 2 347 strains,which displayed a relatively large fingerprint polymorphism.The major PFGE pattern was JPXX01.GD0226,which was found in 97 strains,accounting for 4.13％ (97/2 347).The PFGE patterns in 168 Salmonella 1,4,[5],12:i:-strains were consistent with that of Salmonella typhimurium.Conclusions Salmonella 1,4,[5],12:i:-strains has become the major serotype of Salmonella that cause diarrhea in human in Guangdong.The multi-drug resistance of Salmonella 1,4,[5],12:i:-was serious,and since the defection offljA,fljB and hin genes,the expression of FljBenx protein failed.The PFGE results were diverse,which displayed polymorphism in inheritance.
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Objective To investigate the infection status, serotype distribution, drug sensitivity and molecular characteristics of diarrheagenic Escherichia coli (DEC) in patients with diarrhea in Guangdong Province. Methods Fecal samples were collected, cultured and isolated by traditional methods. Suspected Escherichia coli isolates were confirmed by multiplex PCR used for detecting specific virulence genes and bio-chemical methods. Positive strains were serotyped, characterized for drug sensitivity and analyzed by pulsed-field gel electrophoresis ( PFGE). Results The total positive rate of DEC in patients with diarrhea was 6.26%. The positive rates of enteropathogenic Escherichia coli (EPEC), enterotoxigenic Escherichia coli (ETEC), enterohemorrhagic Escherichia coli (EHEC), enteroadherent Escherichia coli (EAEC) and en-teroinvasive Escherichia coli (EIEC) were 2. 47% , 1. 54% , 1. 32% , 0. 62% and 0. 09% , respectively, with infections primarily in children aged 0-<7 years. The total seropositive rate was 52. 54% , with EHEC accounting for 15. 00% . DEC showed high sensitivity to imipenem, ciprofloxacin, ceftazidime and cefo-taxime. The multidrug resistance rate of DEC was 58. 45% , with EPEC being the most serious for multidrug resistance. PFGE results showed that ETEC, EHEC, EPEC and EAEC had a high degree of polymorphism. Conclusion EPEC is the predominant type of DEC circulating in Guangdong Province. Third-generation cephalosporins are the first drugs of choice for treating infections in children. Ciprofloxacin can be used to treat adults. The problem of multiple drug resistance of DEC is severe and efforts to monitor DEC infections and drug resistance should be strengthened.
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Objective To understand the circulation,drug resistance and molecular characteristics of Salmonella 1,4,[5],12:i:-in human in Guangdong province.Methods Salmonella 1,4,[5],12:i:-isolated from diarrhea patients in Guangdong during 2007-2016 were detected for drug resistance,genes and PFGE characteristics.Results A total of 2 960 strains Salmonella 1,4,[5],12:i:-were isolated from human diarrhea cases during this period.The positive rates of the isolation increased year by year.The male to female ratio of the infection cases was 1.58 ∶ 1,and the infection mainly occurred in infants and young children.Except imipenem,Salmonella 1,4,[5],12:i:-was resistant to other 17 antibiotics to some extent.The drug resistant rates to ceftazidime,cefotaxime and ciprofloxacin increased from 2011 to 2016.Multi-drug resistance was serious,for example,the multi-drug resistant strains with ASSuT accounted for 70.62％ (435/616) and the multi-drug resistant strains with ACSuGSTTm accounted for 27.11％ (167/616).The lack offljA,fljB and hin genes,as well as the retaining of iroB,STM2740,STM2757 genes,resulted in the unable expression of FljBenx gene with 8 different defection profiles.There were 934 different PFGE patterns observed in 2 347 strains,which displayed a relatively large fingerprint polymorphism.The major PFGE pattern was JPXX01.GD0226,which was found in 97 strains,accounting for 4.13％ (97/2 347).The PFGE patterns in 168 Salmonella 1,4,[5],12:i:-strains were consistent with that of Salmonella typhimurium.Conclusions Salmonella 1,4,[5],12:i:-strains has become the major serotype of Salmonella that cause diarrhea in human in Guangdong.The multi-drug resistance of Salmonella 1,4,[5],12:i:-was serious,and since the defection offljA,fljB and hin genes,the expression of FljBenx protein failed.The PFGE results were diverse,which displayed polymorphism in inheritance.
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Objective To investigated the etiologic characteristics of Shigella (S.) sonnei strains causing outbreaks and sporadic cases in some areas of Guangdong province and Guangxi Zhuang Autonomous Region during 2014-2016. Methods Fourteen S. sonnei strains isolated from outbreaks and 6 S. sonnei strains from sporadic cases from Guangdong and Liuzhou of Guangxi Zhuang Autonomous Region were tested for antimicrobial resistance and analyzed by pulsed-field gel electrophoresis (PFGE). Six typical strains were selected for whole genome sequencing typing and compared with 51 strains isolated both at home and abroad from NCBI genome database. Results The antibiotic resistance test indicated the isolates had high resistance rate to ampicillin, tetracycline, gentamicin, trimethoprim/sulfamethoxazole and nalidixic acid, while sensitive to azithromycin, chloromycetin and imipenem. PFGE showed high similarity (93.2%) among the strains isolated from different areas. The whole genome sequencing analysis also revealed that all the typical strains wereclustered into a same evolution branch, close to some strains from Korea. Conclusions The S. sonnei strains isolated from some areas of Guangdong and Guangxi Zhuang Autonomous Region showed high resistance to commonly used antibiotics, but they were sensitive to azithromycin, chloramphenicol and imipenem. The isolates in this study also showed similar PFGE patterns and close phylogenic evolution.
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Objective To analyze the serotype distribution and antibiotic resistance characteristics of Salmonella strains isolated in Guangdong province for better understanding the condition of Salmonella infection in patients with diarrhea.Methods Fecal samples collected from patients with diarrhea in Guangdong province were used to isolate Salmonella strains.Biochemical analysis was performed to identify these isolated strains.Serotyping and antimicrobial susceptibility testing were carried out for further analysis of the isolated Salmonella strains.Results The rate of Salmonella infection was 7.64％in 2015, and the male to female patient ratio was 1.52∶1.A total of 2 377 patients of all age groups were positive for Salmonella infection and the patients aged 0-6 years accounted for 81.74％.The isolation rate of Salmonella strains in the summer and autumn was higher than that in the winter and spring (10.73％ vs 4.24％;X2=463.77, P<0.01).The Salmonella isolation rates in different areas were as follows: 16.82％ in Zhuhai, 15.85％ in Heyuan, 11.81％ in Yangjiang, 10.68％ in Jiangmen, 8.49％ in Zhongshan, 8.07％ in Maoming, 8.05％ in Jieyang, 7.35％ in Shaoguan, 6.97％ in Foshan, 6.03％ in Dongguan, 5.48％ in Guangzhou and 0.00％ in Zhanjiang.And the differences between different regions were statistically significant (X2=367.67, P<0.01).The 2 377 isolated Salmonella strains were classified into 108 serotypes except for oneSalmonella strain that could not be classified.The top four predominant serotypes were 4,5,12:i:-, Salmonella enteritidis,Salmonella stanley and Salmonella typhimurium.Most Salmonella strains were sensitive to imipenem, azithromycin, ceftazidime, cefotaxime and trimethoprim/sulfamethoxazole, but multidrug resistance was common among those strains.Conclusion Salmonella serotypes of 4,5,12:i:-and Salmonella enteritidis are the predominant pathogens causing human Salmonella infections in Guangdong province.Ceftazidime and cefotaximeare are preferred in the treatment of Salmonella infections.Surveillance for drug resistance in Salmonella should be strengthened as multidrug resistant strains have become a serious problem in Guangdong province.
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Objective To investigated the etiologic characteristics of Shigella (S.) sonnei strains causing outbreaks and sporadic cases in some areas of Guangdong province and Guangxi Zhuang Autonomous Region during 2014-2016. Methods Fourteen S. sonnei strains isolated from outbreaks and 6 S. sonnei strains from sporadic cases from Guangdong and Liuzhou of Guangxi Zhuang Autonomous Region were tested for antimicrobial resistance and analyzed by pulsed-field gel electrophoresis (PFGE). Six typical strains were selected for whole genome sequencing typing and compared with 51 strains isolated both at home and abroad from NCBI genome database. Results The antibiotic resistance test indicated the isolates had high resistance rate to ampicillin, tetracycline, gentamicin, trimethoprim/sulfamethoxazole and nalidixic acid, while sensitive to azithromycin, chloromycetin and imipenem. PFGE showed high similarity (93.2%) among the strains isolated from different areas. The whole genome sequencing analysis also revealed that all the typical strains wereclustered into a same evolution branch, close to some strains from Korea. Conclusions The S. sonnei strains isolated from some areas of Guangdong and Guangxi Zhuang Autonomous Region showed high resistance to commonly used antibiotics, but they were sensitive to azithromycin, chloramphenicol and imipenem. The isolates in this study also showed similar PFGE patterns and close phylogenic evolution.
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Objective To prepare simulated stool specimens for proficiency testing ( PT) by mix-ing lentils with Salmonella, Shigella and Escherichia coli strains and to establish an assessment scheme for the detection of Salmonella and Shigella in clinical samples. Methods Salmonella, Shigella and Escherich-ia coli strains were respectively spiked to lentils in Cary-Blair transport medium to create simulated stool specimens. Various ratios of Escherichia coli to Salmonella strains were spiked to lentils to prepare mixed simulated stool specimens. The accuracy and stability of prepared stool samples for PT were tested in-house. Results of sample detection were collected from participating laboratories for further external quality assess-ment. Results The Escherichia coli and Salmonella strains mixed at ratios of 100 ∶ 1 to 106 ∶ 1 could be ef-ficiently isolated from the media. Enrichment was needed in order to effectively isolate Salmonella strains from the media when the ratios of Escherichia coli to Salmonella strains were 104 ∶ 1 to 106 ∶ 1. Of the16 participating laboratories, 14 laboratories (87. 5%) received a grade of“satisfactory” and the other 2 labo-ratories (12. 5%) received a grade of “mainly satisfactory”. Conclusion The simulated stool specimens and the PT procedures designed in this study were suitable for proficiency testing program on the detection of Salmonella, Shigella and other similar microbes.
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Objective To evaluate the role of complement receptor 3 (CR3) on murine macrophages in the recognition of Penicillium marneffei.Methods RAW264.7 murine macrophage cells were cultured in vitro,and divided into four groups to be cocultured with inactivated and live Penicillium mameffei yeast cells as well as inactivated and live Penicillium marneffei conidia respectively at 37 ℃ in 5％ CO2 for one hour.The RAW264.7 cells incubated with phosphate-buffered saline (PBS) served as the blank control group.Then,reverse transcription-PCR was conducted to detect CR3 mRNA expression,Western blot to measure CR3 protein expression,flow cytometry to determine phagocytosis rate,enzyme-linked immunosorbent assay (ELISA) to quantify cytokine levels in culture supernatant.Some RAW264.7 macrophages were transfected with a specific siRNA targeting CR3 gene and cocultured with inactivated Penicillium marneffei conidia,subsequently,phagocytosis rate and supematant cytokine levels were determined.Data were processed by the SPSS 16.0 software,and one-way analysis of variance (ANOVA) was conducted for inter-group comparisons of these parameters.Results No significant differences were observed in the mRNA or protein expressions of CR3 among the four groups of RAW264.7 cells cocuhured with different forms of Penicillium marneffei (both P ＞ 0.05).The phagocytosis rate was 95.14％,89.56％,91.03％ and 90.78％ in RAW264.7 cells cocultured with inactivated conidia and yeast cells,as well as live conidia and yeast cells of Penicillium marneffei,respectively (P ＞ 0.05).The levels of interleukin (IL)-2,interferon (IFN)-γ,IL-4 and IL-10 in culture supernatant were increased at different degrees after one-hour coculture in the four coculture groups compared with the blank control group,but no statistical difference was noted among the four coculture groups in the supernatant levels of these cytokines (all P ＞ 0.05).After coculture with inactivated Penicillium marneffei conidia,the siRNA-transfected RAW264.7 cells showed a statistical decrease in phagocytosis rate (10.89％ vs.92.78％,P ＜ 0.05) and supernatant levels of IL-2,IFN-γ IL-4 and IL-10 compared with untransfected RAW264.7 cells.Conclusions In early stage of innate immunity,CR3 on macrophages may be one of the pattern recognition receptors participating in the recognition and mediation of phagocytosis of Penicillium marneffei.It's possible that both Thl-and Th2-type cytokines,such as IL-2,IFN-γ,IL-4 and IL-10,are involved in the immune response of macrophages against Penicillium marneffei.
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Objective To investigate the role of voltage-gated potassium channel in the human skin squamous cell carcinoma A431 cells and human keratinocyte HaCaT cells. Methods MTT assay was performed to detect the effect of different concentrations of tetraethylammonium (TEA) on the proliferation of cultured A431 cells and HaCaT cells. Besides, enzyme-linked immunosorbent assay (ELISA) was conducted to detect the expression of HERG channel protein in A431 cells, HaCaT cells and normal human skin tissue.Results TEA inhibited the proliferation of A431 cells and HaCaT cells in a dose- and time-dependent manner.After treated with TEA (≥ 10 mmol/L) for 24 or more hours, the proliferation of A431 cells and HaCaT cells was obviously suppressed. A significant difference was observed in the average concentration of HERG channel protein between A431 cells, HaCaT cells and normal human skin tissue (49.7114 ± 3.55696 pg/ml, 35.7471 ±4.14696 pg/ml, 36.8857 ± 3.47810 pg/ml, all P < 0.05). Conclusions The block of voltage-gated potassium channel could inhibit the proliferation of A431 cells and HaCaT cells, and the expression of voltage-gated potassium channel seems to be higher in human skin squamous cell carcinoma cells.