Virulence genes and antimicrobial resistance in Enterococcus strains isolated from dogs and cats in Northeast China

This study aimed to characterize the antimicrobial resistance and virulence of Enterococcus from dogs and cats in Northeast China and evaluate its zoonotic risk based on a total of 469 enterococci strains from 610 samples, including 238 strains of E. faecium and 128 strains of E. faecalis. The isolation rate from police dog samples was 93.79%, pet dog samples was 69.90% and pet cat samples was 76.67%. The differences in the prevalence of E. faecalis among different hosts were statistically significant (P<0.05). The assays showed that most of the virulence genes detected were existed in E. faecalis and police dogs carried the least number of virulence genes. The correlation between enterococcal surface protein (esp) and aggregation substance(asa1) was determined. Enterococci are most resistant to tetracycline and erythromycin, 68.92% of the isolates were classified as multiple drug resistant. Significant differences (P<0.01) were found between E. faecium and E. faecalis in the resistance rates of nine antimicrobials. Four positive and four negative correlations were found between virulence genes and antimicrobial resistance. The results show that Enterococcus colonization and excretion in dogs and cats were related to animal species and living environments. Some correlation between virulence factors and antimicrobial resistance was obtained. This study confirmed the presence of strains carrying multiple virulence factors and antimicrobial resistance at the same time, suggesting a public health risk for dogs and cats as reservoirs of enterococci.

Detection of Two Copies of a blaNDM-1-Encoding Plasmid in Escherichia coli Isolates from a Pediatric Patient with Diarrhea

Purpose

To elucidate the contribution of a transferable plasmid harboring the bla_NDM-1 gene in an Escherichia coli clinical isolate to the spread of resistance determinants.

Methods

Nine extended-spectrum β-lactamase-producing E. coli were collected from diarrhea samples from a pediatric patient and genetic linkage was investigated through enterobacteriaceae repetitive intragenic consensus polymerase chain reaction (PCR). Bacterial species were identified by 16s rRNA sequencing, susceptibility testing with the use of a BD Phoenix^TM-100 Automated Microbiology System, and assessment of virulence genes by PCR. The transferability of bla_NDM-1 in E. coli strain TCM3e1 was confirmed by conjugation experiments. Complete sequencing of E. coli strain TCM3e1 was determined with the PacBio and Illumina NovaSeq platforms and the characteristics were analyzed with bioinformatics software.

Results

The results showed that all nine E. coli strains were the same clone. E. coli strain TCM3e1 was resistant to 12 antimicrobial agents and carried the virulence gene EAST-1. Conjugation transfer analysis showed that bla_NDM-1 was carried on a self-transmissible plasmid. Two copies of the bla_NDM-1 gene were present on an IncC plasmid and some resistance genes with two or three copies were located downstream of the bla_NDM-1 gene and formed a tandem repeat fragment (bla_DNM-1-bleo-sul1- aadA17- dfrA12).

Conclusion

A transmissible plasmid harboring two copies of the bla_NDM-1 gene, including clonal dispersions of the bla_NDM-1 gene, was identified in clinical isolates. These findings emphasized the necessity of surveillance of the plasmid-borne bla_NDM-1 to prevent dissemination.

Pan-Genome Analysis of Vibrio cholerae and Vibrio metschnikovii Strains Isolated From Migratory Birds at Dali Nouer Lake in Chifeng, China

Migratory birds are recently recognized as Vibrio disease vectors, but may be widespread transporters of Vibrio strains. We isolated Vibrio cholerae (V. cholerae) and Vibrio metschnikovii (V. metschnikovii) strains from migratory bird epidemic samples from 2017 to 2018 and isolated V. metschnikovii from migratory bird feces in 2019 from bird samples taken from the Inner Mongolia autonomous region of China. To investigate the evolution of these two Vibrio species, we sequenced the genomes of 40 V. cholerae strains and 34 V. metschnikovii strains isolated from the bird samples and compared these genomes with reference strain genomes. The pan-genome of all V. cholerae and V. metschnikovii genomes was large, with strains exhibiting considerable individual differences. A total of 2,130 and 1,352 core genes were identified in the V. cholerae and V. metschnikovii genomes, respectively, while dispensable genes accounted for 16,180 and 9,178 of all genes for the two strains, respectively. All V. cholerae strains isolated from the migratory birds that encoded T6SS and hlyA were non-O1/O139 serotypes without the ability to produce CTX. These strains also lacked the ability to produce the TCP fimbriae nor the extracellular matrix protein RbmA and could not metabolize trimetlylamine oxide (TMAO). Thus, these characteristics render them unlikely to be pandemic-inducing strains. However, a V. metschnikovii isolate encoding the complete T6SS system was isolated for the first time. These data provide new molecular insights into the diversity of V. cholerae and V. metschnikovii isolates recovered from migratory birds.

[An interlaboratory comparison study on the detection of RUNX1-RUNX1T1 fusion transcript levels and WT1 transcript levels]

Objective: To investigate the current status and real performance of the detection of RUNX1-RUNX1T1 fusion transcript levels and WT1 transcript levels in China through interlaboratory comparison. Methods: Peking University People's Hospital (PKUPH) prepared the samples for comparison. That is, the fresh RUNX1-RUNX1T1 positive (+) bone morrow nucleated cells were serially diluted with RUNX1-RUNX1T1 negative (-) nucleated cells from different patients. Totally 23 sets with 14 different samples per set were prepared. TRIzol reagent was added in each tube and thoroughly mixed with cells for homogenization. Each laboratory simultaneously tested RUNX1-RUNX1T1 and WT1 transcript levels of one set of samples by real-time quantitative PCR method. All transcript levels were reported as the percentage of RUNX1-RUNX1T1 or WT1 transcript copies/ABL copies. Spearman correlation coefficient between the reported transcript levels of each participated laboratory and those of PKUPH was calculated. Results: ①RUNX1-RUNX1T1 comparison: 9 samples were (+) and 5 were (-) , the false negative and positive rates of the 20 participated laboratories were 0 (0/180) and 5% (5/100) , respectively. The reported transcript levels of all 9 positive samples were different among laboratories. The median reported transcript levels of 9 positive samples were from 0.060% to 176.7%, which covered 3.5-log. The ratios of each sample's highest to the lowest reported transcript levels were from 5.5 to 12.3 (one result which obviously deviated from other laboratories' results was not included) , 85% (17/20) of the laboratories had correlation coefficient ≥0.98. ②WT1 comparison: The median reported transcript levels of all 14 samples were from 0.17% to 67.6%, which covered 2.6-log. The ratios of each sample's highest to the lowest reported transcript levels were from 5.3-13.7, 62% (13/21) of the laboratories had correlation coefficient ≥0.98. ③ The relative relationship of the reported RUNX1-RUNX1T1 transcript levels between the participants and PKUPH was not always consistent with that of WT1 transcript levels. Both RUNX1-RUNX1T1 and WT1 transcript levels from 2 and 7 laboratories were individually lower than and higher than those of PKUPH, whereas for the rest 11 laboratories, one transcript level was higher than and the other was lower than that of PKUPH. Conclusion: The reported RUNX1-RUNX1T1 and WT1 transcript levels were different among laboratories for the same sample. Most of the participated laboratories reported highly consistent result with that of PKUPH. The relationship between laboratories of the different transcript levels may not be the same.

Surfactant and inhaled nitric oxide in rats alleviate acute lung injury induced by intestinal ischemia and reperfusion

BACKGROUND

Respiratory distress and acute lung injury (ALI) are severe complications of intestinal ischemia and reperfusion injury (I/R). The authors hypothesize that a combined surfactant and inhaled nitric oxide (iNO) may alleviate I/R-induced ALI.

METHODS

Adult rats (body weight 285 to 315 g, n = 45) were allocated randomly to either a negative control group (N-Control, n = 9) with only sham laparotomy, or groups (n = 9 each) for induction of I/R by occlusion of superior mesenteric artery, followed by treatment with (1) surfactant at 100 mg/kg (Surf), (2) iNO at 20 ppm (NO), (3) both surfactant and iNO (SNO), or (4) no surfactant no iNO (a positive control, P-Control). Mechanical ventilation was provided for 120 minutes with variable peak insufflation pressure and FIO2 to achieve adequate arterial pH, PaO2, and PaCO2. Blood gas values, dynamic lung compliance (Cdyn), and airway resistance (Raw) were measured during the 2-hour treatment. Lung wet-to-dry weight ratio (W/D), histopathology, and morphometric analysis of alveolar expansion (V(V)) were determined at the end of the experiment.

RESULTS

After 120 minutes of treatment, the SNO group had the highest PaO2 and Cdyn values, close to that of the N-Control group. The Surf, NO, and SNO groups had higher V(V) and lower CV (V(V)) values than the P-Control, but modest decrease of W/D values. The NO group had moderately improved PaO2 but Cdyn and V(V) were as low as that of the P-Control. The lungs of the SNO group had significantly alleviated edema and neutrophil infiltration compared with the P-Control.

CONCLUSIONS

The combined surfactant and iNO treatment alleviated rat ALI induced by I/R, and exerted effects better than the use of surfactant or iNO alone.

Prevention of rabbit acute lung injury by surfactant, inhaled nitric oxide, and pressure support ventilation

Improvement of pulmonary perfusion and blood oxygenation and prevention of acute lung injury (ALI) may rely on ventilation strategy. We hypothesized that application of a combined surfactant, inhaled nitric oxide (iNO), and pressure support ventilation (PSV) should more effectively protect the lungs from injury. Anesthetized and intubated adult rabbits weighing 2.8 +/- 0.3 kg were allowed to breathe room air while receiving oleic acid intravenously (60 microl/kg). Within 90 min this caused a reduction of Pa(O(2)) from 94 +/- 7 to 48 +/- 3 mm Hg and dynamic lung compliance (Cdyn) from 1.59 +/- 0.22 to 0.85 +/- 0.10 ml/cm H(2)O/kg (both p < 0.01), and increase of intrapulmonary shunting (Q S/Q T) from 9.4 +/- 1.2 to 27 +/- 5% (p < 0.05). PSV was subsequently applied with 3 cm H(2)O of continuous positive airway pressure and FI(O(2)) of 0.3, and the animals were randomly allocated to four groups, receiving: (1) PSV only (Control, n = 10); (2) iNO at 20 ppm (NO, n = 9); (3) surfactant phospholipids at 100 mg/kg (Surf, n = 8); and (4) surfactant at 100 mg/kg and iNO at 20 ppm (SNO, n = 8). PSV level was varied to maintain a tidal volume of 8 to 10 ml/kg for another 12 h or until early animal death. Five animals in the SNO, three each in the NO and Surf group, and one in the Control group survived 12 h (SNO versus Control, p < 0.05). The NO, Surf, and SNO groups had significantly improved mean Pa(O(2)) (> 70 mm Hg, p < 0.05), and reduced Q S/Q T (15, 19, and 17%, respectively, p < 0.05) at 6 and 12 h, but not in the Control group. The SNO group had the highest values of Cdyn at 12 h, alveolar aeration and disaturated phosphatidylcholine-to-total protein ratio in bronchoalveolar lavage fluid, and the lowest wet-to-dry lung weight ratio and lung injury score (p < 0.05). The results indicate that early alleviation of ALI by surfactant, iNO, and PSV is due to synergistic effects, and only PSV in this model had limited effects.

Effects of inhaled nitric oxide and high-frequency ventilation in rabbits with meconium aspiration

AIM

To evaluate effects of inhaled nitric oxide (iNO) in experimental meconium aspiration treated with high-frequency (HFV) or conventional mechanical ventilation (CMV). Ventilated adult rabbits had meconium instilled intratracheally resulting in respiratory failure as evidenced by more than 50% reduction of dynamic lung compliance (Cdyn) and increase in mean oxygenation index (OI) from 1 to 16. The animals were then allocated to 2 groups treated without (control) or with iNO at 20 ppm (NO). In each group the animals were initially ventilated with CMV or HFV mode for 3 h and then in a crossover fashion with HFV or CMV for another 3 h (CMV-->HFV, HFV-->CMV), respectively. In the first 3 h of treatment, the animals subjected to HFV-CMV in the control, and those with both HFV-CMV and CMV-HFV in the NO group had significantly reduced OI. In the subsequent 3 h, the animals in the control group with CMV-HFV did not improve in OI and those with HFV-CMV had deteriorated. In the NO group with both CMV-HFV and HFV-CMV moderate improvement of OI was observed. Platelet aggregation capability and counts were significantly decreased and bleeding time prolonged in animals receiving iNO treatment. These results suggest that both HFV alone and a combined treatment of iNO with either CMV or HFV are more effective in improving blood oxygenation than that of CMV in this animal model. The influence of iNO on platelet aggregation should be considered.

Comparison of effects of surfactant and inhaled nitric oxide in rabbits with surfactant-depleted respiratory failure

AIM

To compare effects of pulmonary surfactant and inhaled nitric oxide (iNO) in improvement of survival and blood oxygenation in ventilated rabbits with acute hypoxic respiratory failure induced by repeated bronchoalveolar lavage (BAL).

METHODS

After BAL all the rabbits had more than 50% reduction of dynamic lung compliance (Cdya), 50% increment of resistance of respiratory system (Rrs), and an increase of mean oxygenation index (OI) from 1 to 22. The rabbits were then randomly allocated to groups receiving (1) mechanical ventilation only (Control), (2) iNO 0.8 mumol.L-1 (20 ppm) (NO), (3) intratracheal bolus surfactant phospholipids at 100 mg.kg-1 (Surf), and (4) combined surfactant at 100 mg.kg-1 with inhaled NO at 0.8 mumol.L-1 (Surf + NO). All the rabbits were ventilated with standardized tidal volume (8-10 mL.kg-1) for another 8 h or until early death.

RESULTS

The rabbits in both control and NO groups had the lowest survival rate, deterioration of lung mechanics and OI, whereas those in the Surf and Surf + NO groups had modestly improved Cdyn, Rrs, and OI. Only rabbits in the Surf + NO group had significantly improved survival rate and alveolar expansion.

CONCLUSION

Surfactant with or without iNO is more effective compared to the control and iNO groups in rabbit, suggesting that iNO is not effective unless a method to recruit alveoli is applied.

[DNA content analysis of breast cancer cells recognized by monoclonal antibody]

DNA content of breast cancer cells recognized by monoclonal antibody Ki-67 was assayed with flow cytometry in 50 cases. The relationships between sorted or unsorted assay data and metastasis in axillary lymph nodes were analyzed. The results showed that: (1) Aneuploidy rate of breast cancer determined by sorting with Ki-67 was increased and significantly correlated with metastasis in axillary lymph nodes. (2) S-phase fraction (SPF) determined by both sorting and unsorting assay were significantly correlated with axillary lymph node metastasis. (3) Proliferative index (PI) was significantly correlated with axillary lymph node metastasis. This correlation was more significant by sorting with Ki-67. (4) The range of growth fraction (GF) was 28.8%-83.4%, with a mean value of 52.6%. The authors concluded that (1) accuracy of DNA content analysis of breast cancer cells can be increased by sorting with monoclonal antibody Ki-67. (2) DNA ploidy and SPF are important prognostic factors of breast cancer. (3) PI is of great importance in the evaluation of biological behaviours of breast cancer.

[Immune function and abdominal surgery in blood stasis syndrome in patients with gastrointestinal diseases]

52 Patients with Blood Stasis Syndrome (BSS) in abdominal surgical diseases were divided into 3 types according to their symptoms, signs and natures of diseases. Peripheral blood T lymphocyte subsets of these BSS patients and 12 healthy persons were studied with Flow Cytometry and monoclonal antibodies. The immunoglobulins and complements of these cases were also studied. There were no difference in T cell subsets, immunoglobulins and complements between Qizhi-BSS group and normal control. The Shire-BSS group showed that CD8 cell, IgG, IgM, and C1, C3c were increased. These results showed that the immune response increased in this type of BSS patients. In the Qixu-BSS group, the CD3 was nearly normal, and the CD4+, CD4+/CD8+ ratio, and CD16+ were statistically decreased. However, the CD8+ cells markedly increased, the IgG, IgM and IgD were also lowered significantly in this type. The marked morphologic abnormal changes in ultrastructures of T lymphocyte were found in 6 patients with Qixu-BSS group. These results showed that the Qixu type of Blood Stasis Syndrome patients were in the immuno-suppressive status.

Detection of onco-fetal bladder antigen in urine of patients with transitional cell carcinoma

Studies of antigens associated with transitional cell carcinoma were extended by using murine IgM monoclonal antibody E7, developed earlier by this laboratory. These antibodies react preferentially with human bladder tumors and transitional cell carcinoma (TCC) cell line 647V. We now report that monoclonal antibody E7 detected the presence of antigen in midgestational and third trimester amniotic fluids, and in urine of patients with advanced transitional cell carcinoma. Western blot analysis showed that the antigen present in amniotic fluids consists of a sharp band with molecular weight greater than 200 kdaltons. A similar molecular weight pattern was seen with the solubilized membrane of 647V. A sensitive and convenient sandwich ELISA was developed and the urine of patients with bladder cancer was assayed for the presence of the E7 antigen. Antigen was detected in the urine of patients with advanced transitional cell carcinoma but not in the urine of normal adults or in urine from patients with prostate cancer, renal cell carcinoma, or benign prostate hyperplasia. An inhibition enzyme immunoassay was developed with monomeric forms of the E7 antibody and confirmed the presence of antigen in the urine of patients with TCC. We conclude that the E7 antigen is an onco-fetal antigen expressed in patients with transitional cell carcinoma of the bladder.