[Antimicrobial resistance and plasmid-mediated colistin resistance mechanism of diarrheagenic Escherichia coli recovered from foods in parts of China in 2020].

Objective: To investigate the antimicrobial resistance of food-borne diarrheagenic Escherichia coli (DEC) and the prevalence of mcr genes that mediates mobile colistin resistance in parts of China, 2020. Methods: For 91 DEC isolates recovered from food sources collected from Fujian province, Hebei province, Inner Mongolia Autonomous Region and Shanghai city in 2020, Vitek2 Compact biochemical identification and antimicrobial susceptibility testing platform was used for the detection of antimicrobial susceptibility testing (AST) against to 18 kinds of antimicrobial compounds belonging to 9 categories, and multi-polymerase chain reaction (mPCR) was used to detect the mcr-1-mcr-9 genes, then a further AST, whole genome sequencing (WGS) and bioinformatics analysis were platformed for these DEC isolates which were PCR positive for mcr genes. Results: Seventy in 91 isolates showed different antimicrobial resistance levels to the drugs tested with a resistance rate of 76.92%. The isolates showed the highest antimicrobial resistance rates to ampicillin (69.23%, 63/91) and trimethoprim-sulfamethoxazole (59.34%, 54/91), respectively. The multiple drug-resistant rate was 47.25% (43/91). Two mcr-1 gene and ESBL (extended-spectrum beta-lactamase) positive EAEC (enteroaggregative Escherichia coli) strains were detected. One of them was identified as serotype of O11:H6, which showed a resistance profile to 25 tested drugs referring to 10 classes, and 38 drug resistance genes were predicted by genome analysis. The other one was O16:H48 serotype, which was resistant to 21 tested drugs belonging to 7 classes and carried a new variant of mcr-1 gene (mcr-1.35). Conclusion: An overall high-level antimicrobial resistance was found among foodborne DEC isolates recovered from parts of China in 2020, and so was the MDR (multi-drug resistance) condition. MDR strains carrying multiple resistance genes such as mcr-1 gene were detected, and a new variant of mcr-1 gene was also found. It is necessary to continue with a dynamic monitoring on DEC contamination and an ongoing research into antimicrobial resistance mechanisms.

A coronary computed tomography angiography study on anatomical characteristics of the diagonal branch of anterior interventricular artery.

BACKGROUND: This study investigated the anatomical characteristics of the ramus intermedius (RI) and its correlation with the proximal diameter of the branch vessels of the left coronary artery (LCA) using coronary computed tomography angiography (CCTA). MATERIALS AND METHODS: We screened patients who underwent CCTA from January to September 2021 and randomly enrolled 267 with RI (RI group) and 134 without RI (control group). We evaluated the anatomical features of RI (distribution, proximal diameter, length). We measured the proximal diameter of the anterior interventricular branch of the left coronary artery (LAD) and the circumflex branch of the left coronary artery (LCX). We compared the differences between groups in the proximal diameter of LAD and LCX and the correlation between gender and each parameter of the LCA (LAD, LCX, RI) within the RI group. In addition, we compared the correlation between the distribution characteristics of RI and the proximal diameter of LAD and LCX within the RI group. RESULTS: The LAD and LCX proximal diameters in the RI group were significantly smaller than those in the control group (p < 0.05). Comparisons within the RI group showed the following results: the RI distribution, RI diameter and length, and the LCX proximal diameter were not significantly different between male and female patients (p > 0.05), and the LAD proximal diameter was significantly larger in male than in female patients (p < 0.05). There were statistically significant differences in the LAD and LCX proximal diameters between the different RI distribution groups (p < 0.05). Based on the pairwise comparison, there were significant differences in the LAD (LCX) proximal diameter between the RI-beside- -the-LAD (LCX) group and the RI-middle group, as well as between the RI-beside- -the-LAD (LCX) group and the RI-beside-the-LCX (LAD) group (p < 0.05). CONCLUSIONS: A CCTA accurately evaluated the anatomical characteristics of an RI, which has an impact on the proximal diameter of the branch vessels of the LCA (i.e. LAD and LCX), the degree of influence of which is correlated with the RI distribution.

[Antimicrobial resistance and genomic characterization of Campylobacter isolates recovered from retailed poultry meat samples in 20 provinces of China in 2020].

Objective: To understand the antimicrobial resistance and genome characteristics of Campylobacter isolates recovered from retailed poultry meat samples in 20 provinces in China in 2020. Methods: In 2020, 265 Campylobacter strains including 244 Campylobacter jejuni and 21 Campylobacter coli collected from retailed poultry meat samples in China were tested for antimicrobial resistance to 9 antimicrobial compounds by using the agar dilution method. Forty-two selected isolates were sent for whole genome sequencing and 38 high-quality genomes were analyzed for their antimicrobial resistance genes, virulence genes, sequence types and genetic diversity. Results: The resistance rates of Campylobacter isolates from poultry meats to tetracycline, nalidixic acid and ciprofloxacin were the highest (84%-100%), with 53.2% of the isolates showing multidrug resistance in this study. The resistance rates of C. coli to erythromycin, azithromycin, telithromycin, gentamicin and clindamycin were significantly higher than those of C. jejuni (P<0.05). The resistance genes conferring resistance to ß-lactams (100%, 38/38), quinolones (94.7%, 36/38), tetracycline (81.6%, 31/38) and aminoglycosides (50%, 19/38) were the most frequently detected among 38 Campylobacter genomes. C. jejuni carried more virulence genes than C. coli. In total, 19 and 17 sequence types (ST) were obtained from 20 sequenced C. jejuni and 18 C. coli isolates, respectively, including 5 novel STs. The isolates showed a high genetic diversity based on their sequence types. Conclusion: The phenomenon of antimicrobial resistance in Campylobacter from poultry meat sources in China is relatively serious, and resistance and virulence genes are widely distributed in Campylobacter. There is genetic diversity in Campylobacter.

[Efficacy of microscopic surgery for cervical peripheral nerve tumors].

The clinical treatment and follow-up results of 51 patients with cervical peripheral nerve tumors treated by microsurgery in the Department of Neurosurgery of Beijing Friendship Hospital Affiliated to Capital Medical University from January 2016 to October 2021 were retrospectively analyzed. Total tumor resection was performed in 49 patients (96.1%), and 42 patients (82.4%) had no obvious neurological impairment. During the follow-up of the 45 cases, 43 cases had no recurrence in situ. Two cases had recurrence (residues from the initial surgery) and accepted the reoperation. Microsurgery of cervical peripheral nerve tumor, combined with intraoperative neurophysiological monitoring, can remove the tumor to the greatest extent and protect the important peripheral blood vessels and nerves. The clinical efficacy and follow-up results are good.

[The expression of P19ink4d in the pathogenesis and development of hearing loss].

Objective: This study aimed to investigate the P19ink4d expression in cochlea of mice model with noise induced hearing loss and the role of P19ink4d in the degeneration of inner ear cells. It also searched for P19ink4d gene alterations in patients with profound sensorineural deafness.Method: CBA/J mice were exposed to broad band noise at 101 dB SPL for 2 hours, auditory brainstem response (ABR) were examined to confirm noise lead to the permanent threshold shift. Immunohistochemical staining, Western blotting, and real-time polymerase chain reaction (PCR) were performed on cochlear tissues, to elucidate changes in P19ink4d expression in mice after noise exposure. For clinical evaluation, 400 children from unrelated families with severe or profound sensorineural hearing loss (SNHL) were recruited, genomic DNA was obtained from the patients and was subjected to DNA microarray to screen mutations in 4 most common genes. The sample that carried none of the common mutant alleles were subjected to PCR and sequenced to detect mutations in P19ink4d gene.Result: The ABR threshold shift of mice in the experimental group significantly increased after noise exposure and was higher than that in the null-noise group. The ABR of 1 day post noise was least among experimental groups and there is no statistical different between ABR of 7 days and 14 days post noise. The missing of outer hair cells occurred after noise exposure, while the inner hair cells hardly miss. It was found that the P19ink4d expression increased significantly in the inner ear cells 3 hours after noise exposure, then recovered in 24 hours. Western blot indicated that the amount of P19ink4d increased transitorily 3-6 h after the noise. However, no mutation existed within the coding exons of P19ink4d in the patients with profound sensorineural deafness.Conclusion: The results support the concept that P19ink4d may play an important role in the pathogenesis and development of noise induced hearing loss.

[Molecular typing characterization of food-borne methicillin-resistant Staphylococcus aureus in China].

Objective: To analyses the antimicrobial resistance and molecular characterization of 21 MRSA isolates cultured from retail foods from different provinces in China, and evaluate the molecular typing methods. Methods: Twenty-one MRSA isolates were obtained from national foodborne pathogen surveillance network in 2012 (Chinese salad, n=3; milk, n=1; cake, n=2; rice, n=1; cold noodle, n=1; spiced beef, n=1; dumpling, n=1; packed meal, n=1; salad, n=1; raw pork, n=9). The antimicrobial resistance of 21 strains to 12 antimicrobial agents was tested by broth dilution method. Polymerase chain reaction (PCR) and DNA sequencing were performed to obtain the genetic types of MLST (ST) and spa typing. The clonal complex (CC) was assigned by eBURST soft and the MLVA type (MT) and MLVA complex (MC) were identified via the database of the MLVA website (http://www.mlva.net). SmaI pulsed-field gel electrophoresis (SmaⅠ-PFGE) was also carried out to obtain the PFGE patterns of 21 strains. The genetic diversity and discriminatory power of typing were calculated by the Simpson's index of diversity (diversity index, DI) to find out the best genotyping method for MRSA. Results: All MRSA isolates showed multi-drug resistance(MDR), and were resistant to oxacillin, benzylpenicillin, clindamycin and erythromycin, and 71.4% (15/21), 47.6% (10/21), 42.9% (9/21) and 28.6% (6/21) of the MRSA isolates were resistant to tetracycline, ciprofloxacin, trimethoprim/sulfamethoxazole and gentamicin, respectively. Moreover, one strain was found to be resistant to all three antimicrobials of levofloxacin, moxifloxacin and rifampicin. Great diversity was found in these food-associated MRSA (6 STs, 7 spa types, and 9 MTs). PFGE patterns were more diverse than those of other three molecular typing methods (19 pulse types). The index of diversity (DI) of PFGE, MLVA, spa typing and MLST was 0.99, 0.80, 0.73, and 0.61, respectively. Among the MRSA isolates, CC9-ST9-t899-MT929-MC2236 (PFGE Cluster Ⅴ) was the most prevalent clone, which were all cultured from raw pork (9 isolates). Besides, two MRSA were identified as CC59-ST338-t437-MT621-MC621 (PFGE Cluster Ⅳ). Different clone had their own resistance spectrum profiles. Conclusion: The food-borne MRSA isolates were all MDR in this study. Different clones had their own resistance spectrum profiles. MLVA represented a promising tool for molecular epidemiology tracing of MRSA in foodborne disease events.

[Laboratory-based characterization and traceability of an outbreak of necrotising enterocolitis].

Objective: Laboratory-based characterization and traceability were performed on an outbreak of necrotising enterocolitis (NEC) happened in a maternal and child health care hospital in China. Methods: Thirty-seven samples were collected from 3 NEC cases, that the clinical manifestations was bloody stools. Clostridium spp. isolation and identification were carried out on stool, breast milk, milk-based infant powder and environmental swab samples collected during NEC outbreak from October to November in 2016. Meanwhile, twenty-four swabs samples from ward environmental, staffs' hand as well as articles for neonates daily use were also collected and tested for Clostridium spp. after disinfection following outbreak. Pulsed-field gel electrophoresis (PFGE) analysis was performed on all Clostridium strains obtained. Results: 46% (17/37) samples were positive for a presumptive Clostridium spp. during the outbreak of NEC. One type of Clostridium spp. isolates was cultured from 10 samples including the hands of medical staffs, some medical equipments in the ward and milk-based infant powder ingested by the case, it was identified as C.butyricum. Another type of Clostridium spp. isolates was cultured from 2 samples including breast milk and inner wall of breast milk fresh-keeping bag, it was identified as C.sporogens. Both of these two types isolates were cultured from 5 samples including inner wall of breast milk box, inner wall of refrigerator, the handle of case's incubator and the case's stool. PFGE analysis showed that all 15 strains of C. butyricum and 7 strains of C.sporogens isolated from the samples mentioned above produced indistinguishable pulsotypes respectively. No NEC cases were found after disinfection following the outbreak and all samples collected after outbreak were negative for Clostridium spp. Conclusion: The outbreak of NEC was highly related to C. butyricum contamination within the hospital.