Investigation into the prevalence of enterotoxin genes and genetic background of Staphylococcus aureus isolates from retain foods in Hangzhou, China.

BACKGROUND: Staphylococcus aureus expresses numerous toxins, many of which are strongly believed to be responsible for specific symptoms and even diseases, making it significant in the pathogenesis of human health. Enterotoxins, which are vital toxins, are associated with foodborne illnesses that manifest through symptoms like vomiting and diarrhea. In the present study, 264 S. aureus isolates obtained from various retail foods in Hangzhou, China were further investigated the profiles of enterotoxin genes and genetic backgrounds. RESULTS: Approximately, 64.02% of the isolates from diverse sources contained at least one Staphylococcal Enterotoxin (SE) genes, displaying a total of 36 distinct combinations. Enterotoxin gene cluster (egc) encoded enterotoxin genes, normally designated by seg, sei, sem, sen, seo and selu, plus with sep were more frequently detected (33.73%, each). In contrast, see, ses and set were absent in any of the isolates tested. A total of 44 sequence types (STs), 20 clonal complexes (CCs) and 66 different staphylococcal protein A (spa) types (including six novel types) were identified among those 169 SE-positive isolates. Moreover, nineteen methicillin-resistant Staphylococcus aureus (MRSA) isolates were identified. The majority of those isolates belonged to the CC59-Sccmec IVa cluster and carried the seb-sek-seq gene cluster. The egc cluster, either coexisting with or without other enterotoxin genes, was observed in all isolates allocated into CC5, CC9, CC20, CC25, CC72 and ST672. Irrespective of the spa types and origins of the food, it appeared that seh was a distinct genetic element present in isolates belonging to the CC1 clonal lineage. CONCLUSIONS: The results not only proposed a suspected relationship between distribution of enterotoxigenic strains and genetic backgrounds, but also attributed the presence of novel enterotoxins to potential hazards in food safety.

Epidemiological and molecular evidence of foodborne poisoning outbreak caused by enterotoxin gene cluster-harboring Staphylococcus aureus of new sequence type 7591.

OBJECTIVES: This paper presented a detailed analysis of the epidemiology and molecular characteristics of staphylococcal food poisoning (SFP) that occurred in a hotel in Hangzhou. METHODS: A total of 46 guests at the hotel underwent an epidemiological survey. Samples of stool from patients, vomit, swabs from the kitchen, leftover food items, and anal swabs from food handlers were taken and investigated for the presence of potential pathogenic bacteria. Molecular techniques and whole genome sequencing were performed to track the evolution of Staphylococcus aureus associated with the outbreak of SFP. RESULTS: Forty-six individuals displayed gastrointestinal symptoms. Seventeen isolates of S. aureus were discovered to carry the seg, sei, sem, sen, seo, and selu genes found in a specific enterotoxin gene cluster (egc) operon, but without the presence of classical enterotoxins such as SEA ∼ SEE. All egc-positive isolates shared identical pulsed-field gel electrophoresis profiles and were classified under new ST7591 (Clonal Complex 72) with identical spa typing t148. In addition, some isolates of S. aureus obtained from food sources sold in Hangzhou over the past 3 years and carrying egc genes were grouped under the ST72 lineage (CC72). Through whole genome sequencing, a strong genetic connection was revealed between these egc-positive isolates and clinical ST72 S. aureus found in China. CONCLUSIONS: S. aureus with non-classical egc enterotoxins was suggested to be a potential cause of SFP in humans.

Bacteriological Studies of Venomous Snakebite Wounds in Hangzhou, Southeast China.

Snakebite is a common occurrence in Hangzhou, and identifying bacteria in wounds is very important for snakebite treatment. To define the pattern of wound bacterial flora of venomous snakebites and their susceptibility to common antibiotics, we reviewed the medical charts of patients admitted with snakebite at Hangzhou TCM Hospital from January 2019 to December 2020. A total of 311 patients were enrolled in this study. Among them, bacteria culture was positive in 40 patients, and 80 organisms were isolated. The most frequent pathogens were Morganella morganii and Staphylococcus aureus. According to the results of susceptibility testing, a majority of the isolates were resistant to some common first-line antibiotics, such as ampicillin, ampicillin/sulbactam, amoxicillin/clavulanic acid, cefoxitin, and cephazolin. Quinolones, however, have shown a better antibacterial effect. In conclusion, snakebite wounds involve a wide range of bacteria. Fluoroquinolones, such as levofloxacin and ciprofloxacin, could be an alternative for empirical treatment in patients with snakebite when the effect of other antibiotics is poor.

A high value of fibrinogen in immunoglobulin A nephropathy patients is associated with a worse renal tubular atrophy/interstitial fibrosis score.

PURPOSE: The purpose of our study was to investigate the relationship between serum fibrinogen value and renal tubular atrophy/interstitial fibrosis in immunoglobulin A nephropathy patients with eGFR ≥90 ml/min/1.73 m2 . PATIENTS AND METHODS: Of 359 patients diagnosed with immunoglobulin A nephropathy after renal biopsy were enrolled in this retrospective study. Demographic, histopathological features, and clinical data were collected. The relationships among these factors were analyzed by using Student's t test, Mann-Whitney U test, Kruskal-Wallis test, Chi-square test, or Fisher's exact test, where appropriate. The logistic regression analysis was performed to examine the independent risk factors. RESULTS: Of 176 immunoglobulin A nephropathy patients with eGFR ≥90 ml/min/1.73 m2 were included in this study, and patients were classified into low fibrinogen (fibrinogen <304.6 mg/dl) and high fibrinogen (fibrinogen ≥304.6 mg/dl) groups, respectively. High fibrinogen groups had advanced age, a higher classification of renal tubular atrophy/interstitial fibrosis, and higher levels of systolic pressure, D-dimer, 24 h urine protein quantitation, nag enzyme. Multivariate logistic analysis showed that fibrinogen (OR = 1.018) was significantly associated with tubular atrophy/interstitial fibrosis. CONCLUSION: Among patients with immunoglobulin A nephropathy, the higher levels of fibrinogen and uric acid may mean a higher score of tubular atrophy/interstitial fibrosis, which suggests the renal biopsy should be performed for these patients as early as possible to defined pathological classification, even though there is no obvious abnormal change in the test of renal function.

Characterization of the genetic environment of blaKPC in Escherichia coli isolates from hospitals in China.

Carbapenem resistance in Enterobacteriaceae members has become a major challenge, and the genetic environment of blaKPC, encoding Klebsiella pneumoniae carbapenemases, has not been fully clarified in China. In this study, we aimed to explore the genetic environment of blaKPC in 25 carbapenem-resistant E. coli isolates from hospitals in Hangzhou Province, China. Antimicrobial susceptibility against 22 common antimicrobial agents was tested. Polymerase chain reaction (PCR) analysis was performed for screening of the resistent genes, such as blaKPC, blaCTX-M, blaTEM, blaSHV, blaNDM, qnrA, qnrB, qnrS, aac(6')-Ib, armA and rmtB. The genetic environment of blaKPC were determinedin one isolate. blaKPC was detected by PCR in all the clinical E. coli isolates. There were no strains carrying blaNDM, qnrA and armA. The genetic environment of blaKPC showed that blaKPC dissemination is plasmid mediated and that it is located in the Tn3-Tn4401 transposon complex. Encoding of blaKPC-2 was responsible for carbapenem resistance in the 25 E. coli isolates. The genetic environment of blaKPC was characterized by the Tn3-Tn4401 complex. Our findings may provide a theoretical basis for clinical drug-resistance monitoring, anti-infection treatment and hospital infection control.

Betaine suppressed Aß generation by altering amyloid precursor protein processing.

Betaine was an endogenous catabolite of choline, which could be isolated from vegetables and marine products. Betaine could promote the metabolism of homocysteine in healthy subjects and was used for hyperlipidemia, coronary atherosclerosis, and fatty liver in clinic. Recent findings shown that Betaine rescued neuronal damage due to homocysteine induced Alzheimer's disease (AD) like pathological cascade, including tau hyperphosphorylation and amyloid-ß (Aß) deposition. Aß was derived from amyloid precursor protein (APP) processing, and was a triggering factor for AD pathological onset. Here, we demonstrated that Betaine reduced Aß levels by altering APP processing in N2a cells stably expressing Swedish mutant of APP. Betaine increased α-secretase activity, but decreased ß-secretase activity. Our data indicate that Betaine might play a protective role in Aß production.

Emergence of Klebsiella pneumoniae carbapenemase-producing Escherichia coli sequence type 131 in Hangzhou, China.

BACKGROUND: Klebsiella pneumoniae carbapenemase (KPC)-producing Escherichia (E.) coli has been reported in China since 2008. However, there is no information about the molecular epidemiology of KPC-producing E. coli in China. In this study, we aimed to investigate the sequence type (ST) and characteristics of KPC-producing E. coli isolates in China. METHODS: Three carbapenem-resistant isolates of E. coli (E1, E2, and E3) from one teaching hospital in Hangzhou covering a one year period were analyzed. Antibiotic susceptibility was determined by Etest. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were used for epidemiological analysis. The genetic structure around blaKPC, the major plasmid incompatibility typing, and the identification of ß-lactamase gene types were performed by PCR and the positive products were subsequently sequenced. Plasmids were analyzed by transformation, restriction, and Southern blotting. RESULTS: PFGE demonstrated that patterns of isolates E1 and E2 were clonally-related and designated as patterns A1 and A2; pattern of isolate E3 was different and designated as pattern B. MLST analysis showed that the three isolates displayed one common sequence type ST131. The identification of bla gene types by PCR and sequencing showed that blaKPC-2, blaCTX-M-14, and blaTEM-1 were detected in all three isolates. All three isolates carried a KPC-2-encoding plasmid of the IncN replicon. Plasmid analysis and hybridization experiments showed that the isolates were found simultaneously to carry two or four plasmids. The blaKPC-2 gene in E1 and E2 was located in a plasmid with size of ca. 50 kb. However, the blaKPC-2 gene in E3 was located in a plasmid with size of ca. 130 kb. CONCLUSIONS: E. coli ST131 with KPC-2 ß-lactamase has emerged in China, which enlarges the geographical area where the ST131 KPC-producing E. coli strains have diffused.

[Isolation of rabbit aqueous humor-derived exosomes and their immunosuppression function].

OBJECTIVE: To isolate exosomes from rabbit aqueous humor and to investigate their immunosuppression function. METHODS: Aqueous humor was collected from 40 New Zealand rabbits and exosomes were isolated by fractional separation and ultracentrifugation methods; the morphology was studied with electron microscopy. The immunosuppressive-related proteins of exosomes were detected with Western blotting; their inhibitory effect on ConA-induced proliferation of T lymphocyte was estimation with CCK-8 cells proliferation assay. RESULTS: Eight milliliters of aqueous humor were collected from 40 New Zealand rabbits and 200 µg exosomes was yielded. Under electron microscope, the exosomes had typical structure of lipid bi-layer with a diameter of 50-100 nm. The results of Western blotting showed that these exosomes expressed Hsp70, CD9 and Alix but not Grp94, presenting a typical exosomes protein profile. Moreover, exosomes expressed high level of TGF-ß and significantly inhibited the proliferation of T lymphocytes. CONCLUSION: Immunosuppressive exosomes can be isolated from rabbit aqueous humor, which may be involved in immunotolerance of the eye.