Prevalence, resistance phenotypes, and fluoroquinolone resistance genes of Salmonella isolates from raw milk of healthy dairy cows in Henan province, China.

OBJECTIVE: Salmonella isolates have been discovered in many regions of the world. We investigated the prevalence and resistance of Salmonella isolates in raw milk of healthy dairy cows on farms in different regions of Henan Province, China. MATERIALS AND METHODS: From July 2020 to November 2021, 422 raw milk samples were collected. The minimum inhibitory concentrations (MICs) of 16 antimicrobial agents against 89 Salmonella strains detected from the raw milk samples were determined using the broth microdilution method, and the resistance genes for fluoroquinolones were identified using polymerase chain reaction. RESULTS: Eighty-nine (21.09%) Salmonella isolates were recovered from 422 raw milk samples. The Salmonella strains exhibited high resistance to amoxicillin (100.00%), tylosin (95.50%), and lincomycin (95.50%). Additionally, tigecycline showed good activity against Salmonella, with an MIC50 of 0.25 µg/mL. All Salmonella isolates showed multidrug resistance (MDR), and >50% of the strains showed resistance to more than six antimicrobials. The strains from Jiaozuo exhibited 100% resistance to amoxicillin, terramycin, tylosin, and lincomycin. Two efflux pump genes, oqxA and oqxB, had the highest carrying rates of 66.29% and 64.04%, respectively. Additionally, the carrying rates of oqxA and oqxB were high in Shangqiu, Zhengzhou, and Jiaozuo. The carrying rates of aac(6')-Ib-cr in Shangqiu and Zhengzhou were 33.33% and 38.46%, respectively. CONCLUSIONS: This study revealed a high prevalence of Salmonella isolates obtained from raw milk of healthy dairy cows in different regions of Henan Province, China. The Salmonella strains exhibited various degrees of MDR. Salmonella can be transmitted to humans via consumption of contaminated raw milk; thus, the presence of resistance genes poses a potential threat to public health, highlighting the need for vigilant monitoring of Salmonella isolates.

Antimicrobial mechanisms of traditional Chinese medicine and reversal of drug resistance: a narrative review.

OBJECTIVE: In recent years, the extensive use of antibiotics worldwide has led to an increase in the number of drug-resistant bacterial strains, thus resulting in an increasingly severe degree of bacterial resistance. For thousands of years, traditional Chinese medicine (TCM) has provided natural and unique advantages in the treatment of infectious diseases. Therefore, it is important to develop further and use TCM to treat clinical infections caused by drug-resistant bacteria. MATERIALS AND METHODS: A literature search was performed using PubMed, Web of Science, Google Scholar, and the China National Knowledge Infrastructure databases. The articles were analyzed to extract information on the antimicrobial effects of Chinese herbal medicines, compounded Chinese medicines, monomeric compounds of herbal origin, and the combined use of Chinese medicine and antimicrobial drugs and to determine the synergistic effect of the combination of Chinese medicine and antibiotics, as well as investigate the possibility of restoring the antibiotic sensitivity of drug-resistant strains. RESULTS: The mechanisms underlying the antibacterial properties of TCM involve altering membrane permeability, inhibiting protein and nucleic acid synthesis, inhibiting enzyme activity in vivo, and controlling the ability of pathogenic bacteria. In addition, the mechanism underlying TCM-induced reversal of bacterial drug resistance is discussed, particularly in terms of the elimination of resistant (R) plasmids and the inhibition of extended-spectrum ß-lactamases, bacterial biofilm formation, and bacterial efflux pump activity. CONCLUSIONS: This paper reviewed the recent relevant literature on antimicrobial action and its mechanisms, as well as the mechanisms of drug resistance reversal by TCM to provide a reference for clinical drug use, prevention and control of bacterial infection, and research and development of new drugs.

Research progress on the oxazolidinone drug linezolid resistance.

OBJECTIVE: The oxazolidinone drug linezolid is mainly used for severe infections caused by multidrug-resistant Gram-positive bacteria. However, emerging linezolid resistance is aggravating difficulties in the treatment of certain infectious diseases. The objective of this review was to provide a reference for researchers and clinicians to be able to better face together the serious challenge of antimicrobial resistance. MATERIALS AND METHODS: A systematic literature search was performed using PubMed, Web of Science, Google Scholar, and the China National Knowledge Infrastructure (CNKI) database. The articles were scrutinized to extract information on oxazolidinone drug linezolid resistance, and the prevalence of the resistance gene optrA. We reviewed the latest advances in epidemic properties, resistance mechanism, and transfer mechanism of linezolid resistance genes in different isolates isolated from various samples worldwide. RESULTS: Initially, it was thought that linezolid resistance was related to the change in drug target mediated by mutations in the 23S rRNA gene, rplC, rplD, and cfr. optrA was discovered in 2015, and is a gene encoding oxazolidinone resistance, which exists in both plasmids and chromosomes, but mostly plasmids. The emergence of the novel plasmid-borne ABC transporter gene optrA expanded the understanding of the mechanism of linezolid resistance. CONCLUSIONS: At present, the prevalence of linezolid resistance has become increasingly serious. The resistance gene optrA has been reported in Enterococcus, Staphylococcus squirrel and Streptococcus, which indicates that this gene has a strong ability to spread across bacteria, so the prevalence and spread of optrA gene should be monitored carefully.

[Recommendations for normalizing the medical practices of burn treatment during the outbreak of coronavirus disease 2019].

2019 novel coronavirus (2019-nCoV) is one of the beta coronaviruses and is identified as the pathogen of the severe " coronavirus disease 2019 (COVID-19)" in 2019. China manages COVID-19 according to the reguirement of the highest level infectious diseases in China. Currently, the prevention and control of COVID-19 in China is at a critical period. Burn Department as an emergency discipline is confronted with risk of 2019-nCoV infection. Based on the guidelines for the diagnosis and treatment of COVID-19 (6th trial edition), in combination with the latest literature at home and abroad, the features of the COVID-19, the recommendations for the COVID-19 prevention and control issued by the National Health Commission of China, and the management experience of COVID-19 diagnosis and treatment of other related disciplines, we put forward some recommendations for the medical practices of burn treatment during the outbreak of the COVID-19 in outpatient and emergency, inpatient treatment, and the management of operation theatres and wards, etc. We hope these recommendations could benefit the medical professionals in the field of burn treatment and relevant hospital management during the outbreak of COVID-19, improve burn treatment, and avoid or reduce the risk of infection of medical staff.

[Retrospective study on the characteristics of early organ injury in elderly patients with severe burns].

Objective: To analyze the clinical characteristics of early organ injury in elderly patients with severe burns and the effects on the prognosis of patients. Methods: From January 2010 to August 2018, 62 patients with severe burns (43 men and 19 women, aged from 60 to 89 years at the time of admission) who were hospitalized in the Institute of Burn Research of the First Affiliated Hospital of Army Medical University (the Third Military Medical University, hereinafter referred to as the author's affiliation), meeting the inclusion criteria, were included in elderly (E) group, and 124 patients with severe burns (86 men and 38 women, aged from 18 to 59 years at the time of admission) at the same term were included in young and middle-aged (YM) group. Treatment of patients in the 2 groups followed the conventional procedures of the author's affiliation. The following data of patients in the 2 groups were retrospectively analyzed. (1) Fluid replacement volume and urine volume within the first and second post injury hour (PIH) 24 were recorded. The levels of hemoglobin, haematocrit, and blood lactic acid at admission, PIH 24 and 48 were recorded. (2) The creatine kinase isozyme-MB (CK-MB), total bilirubin, blood creatinine, oxygenation index, and blood platelet count at admission, at shock stage, and on post injury day (PID) 3 to 7 were collected. (3) The days of seriously or critically ill and deaths were recorded. Data were processed with chi-square test, group t test, Mann-Whitney U test, analysis of variance for repeated measurement, and Bonferroni correction. Results: (1) There were no statistically significant differences in fluid replacement volume within the first and second PIH 24, and urine volume within the second PIH 24 between patients in the 2 groups (t=0.351, 1.307, 1.110, P>0.05). The urine volume of patients in group E within the first PIH 24 was significantly less than that in group YM (t=5.628, P<0.05). There were no statistically significant differences in levels of hemoglobin (t=0.011, 1.075, 0.239), haematocrit (t=0, 0.033, 0.199), and blood lactic acid (t=0.017, 1.002, 0.739) at admission, PIH 24 and 48 between patients in the 2 groups (P>0.05). (2) There were no statistically significant differences in levels of CK-MB at admission and on PID 3 to 7 between patients in the 2 groups (t=0.069, 0.001, P>0.05). The level of CK-MB of patients in group E at shock stage was significantly higher than that in group YM (t=4.017, P<0.05). There were no statistically significant differences in levels of total bilirubin at admission and on PID 3 to 7 between patients in the 2 groups (t=0.227, 0.002, P>0.05). However, the level of total bilirubin of patients in group E at shock stage was significantly higher than that in group YM (t=6.485, P<0.05). The levels of blood creatinine of patients in group E at admission and shock stage were significantly higher than those in group YM (t=4.226, 12.299, P<0.05 or P<0.01), while there was no statistically significant difference between them on PID 3 to 7 (t=0.693, P>0.05). The oxygenation indexes of patients in group E at admission and shock stage and on PID 3 to 7 [(371±16), (263±16), and (228±18) mmHg (1 mmHg=0.133 kPa)] were lower than (420±13), (327±13), and (281±17) mmHg of patients in group YM, respectively (t=5.650, 9.782, 4.856, P<0.05 or P<0.01). There were no statistically significant differences in levels of blood platelet count at admission and shock stage between patients in the 2 groups (t=0.038, 0.588, P>0.05), while the level of blood platelet count of patients in group E on PID 3 to 7 was significantly lower than that in group YM (t=6.636, P<0.05). (3) The days of seriously or critically ill and death rate of patients in group E were respectively longer or higher than those in group YM (Z=-2.303, χ(2)=13.676, P<0.05 or P<0.01). Conclusions: In the case of the same tissue perfusion at shock stage, injuries in heart, liver, kidney, lung, and coagulation system in elderly patients with severe burns are more obvious than those in young and middle-aged patients, with more severe illness and higher mortality.

Genetic variations in the active efflux pump genes acrA/B and tolC in different drug-induced strains of Escherichia coli CVCC 1547.

This study aimed to investigate the properties of mutations of the active efflux pump genes acrA/B and tolC in Escherichia coli CVCC 1547 when induced by different drugs. The mutations were isolated in vitro by exposing E. coli CVCC 1547 to stepwise increases in the concentration of ceftriaxone (CRO), amikacin (AMK), or ciprofloxacin. The results showed that the minimum inhibitory concentrations for the corresponding drugs increased, as did the minimum inhibitory concentrations for other fluoroquinolones and ß-lactam drugs that were not inducers. DNA sequence analyses of the acrA/B and tolC genes of the mutants and comparison with the parent strain revealed that genetic variations had occurred. Three point mutations resulted in amino acid changes in the proteins expressed. Specifically, strain CRO10 had a mutation in acrA, A309G, that resulted in a Thr-103 to Ala substitution, and a mutation in tolC, G735A, that changed Ala-245 to Thr; strain AMK20 (and AMK30) had a Val-447 to Ile amino acid change in acrB. In addition to the missense mutations in these strains, we detected 7, 20, and 15 nonsense mutations in acrA, acrB, and tolC, respectively. To sum up, multiple genetic sequence variations and some changes in amino acid sequences were detected when E. coli CVCC 1547 was challenged in vitro with CRO, AMK, or ciprofloxacin. These changes may have given rise to multidrug-resistant strains.

Phenotypic and molecular characterization of CTX-M-14 extended-spectrum ß-lactamase and plasmid-mediated ACT-like AmpC ß-lactamase produced by Klebsiella pneumoniae isolates from chickens in Henan Province, China.

Extended-spectrum ß-lactamases (ESBLs) and AmpC ß-lactamases produced by a clinical isolate of Klebsiella pneumoniae from chickens were detected with confirmatory phenotypic tests of the Clinical and Laboratory Standards Institute. The minimum inhibitory concentrations of 18 antibacterial drugs against K. pneumoniae were determined by the 2-fold microdilution method. The genotype and subtype of the ESBL-producing and AmpC ß-lactamase-producing K. pneumoniae isolate were identified by PCR amplification of the enzyme-encoding genes followed by DNA sequencing analysis. K. pneumoniae K(1) isolate was an ESBL-producing and AmpC ß-lactamase-producing bacteria with high resistance to ß-lactam antibiotics, such as penicillins, third-generation cephalosporins, fluoroquinolones, and aminoglycosides. The sequence analysis showed that K. pneumoniae K(1) harbored TEM-type, SHV-type, CTX-M-type, and ACT-type AmpC ß-lactamase nucleotide sequences. The TEM-type sequence was designated as TEM-1; the SHV-type sequence was designated as SHV-11; the CTX-M-type sequence was designated as CTX-M-14. Compared with the ACT-like sequence (EF078894), the ACT-type sequence was characterized by 8 nucleotide mutations (A(75)G, C(84)G, T(90)C, A(105)G, G(213)A, G(246)A, C(309)T, and T(315)C). Only one mutation at position 75 led to an amino acid substitution (Asn28Lys). The bla(ACT) type was an ACT-like derivative.

Thymidine kinase 1 is a potential marker for prognosis and monitoring the response to treatment of patients with breast, lung, and esophageal cancer and non-Hodgkin's lymphoma.

Thymidine kinase 1 (TK1) is converting thymidine to thymidine monophosphate, and is related to DNA replication and cell proliferation. The use of the TK1 protein levels as a proliferation marker in malignancies is here summarized. TK1 protein in serum (STK1p) and TK1 expression in tissues were determined by a chemoluminescent dot blot assay and by immunohistochemistry staining, respectively. The expression of TK1 in tumor tissues correlated to pathological stages and clinical grades of carcinomas (ca) of esophagus, lung and in premalignancy of breast ductal ca. STK1p could monitor the out-come of tumor therapy by being correlated to remission [breast ca, non-Hodgkin's lymphoma], relapse [breast ca] and to survival [non-Hodgkin's lymphoma] of patients. In a health screening study of 12,641 persons, STK1p seemed to predict the risk of development of neoplasia related diseases at early stage.

[Changes in T-lymphocyte subsets of peripheral blood in patients with filarial chyluria].

OBJECTIVE: To study the changes in T-lymphocyte subsets CD4+:CD8+ of peripheral blood in 29 patients with present chyluria(PPC), 29 patients with chyluria history but without chyluria (PNPC) and 38 healthy controls. METHODS: The determination of CD3+, CD4+ and CD8+ was conducted using test reagents kits. RESULTS: The percentage of CD3+, CD4+ cell were signfcantly decreased in PPS group than in PNPC and healthy control group, the ratio of CD4+/CD8+ being under 1.0. The T-lymphocyte subsets (CD3+, CD4+, CD8+) and CD4+/CD8+ ratio of both PNPC and healthy control group were all within normal range. CONCLUSION: The immune function of the patients with filarial chyluria was impaired in terms of the changes in T-lymphocyte subsets.

Comparative plasma and tissue pharmacokinetics and drug residue profiles of different chemotherapeutants in fowls and rabbits.

Blood and tissue pharmacokinetics and drug residue profiles of six chemotherapeutants were studied. Ceftriaxone (CEF), intravenously at 50 mg/kg, sulfamonomethoxine (SMM) and sulfaquinoxaline (SQ), orally at 200 mg/kg, and olaquindox (OLA), orally at 50 mg/kg, were administered to young broilers. Penicillin (PEN), intramuscularly at 200,000 U/kg, and albendazole (ALB), orally at 20 mg/kg, were given to rabbits. For each drug, 13-18 groups (n = 5-10 individuals/group) of the dosed animals were killed at different post-dosing times. Drug and/or metabolite concentrations in plasma, liver, kidney, heart, lung, and muscle tissues were analysed by HPLC procedures. Multi-exponential kinetic models were fitted to the observed tissue concentration-time data by applying a non-linear least-squares regression computer program. Tissue half-life, peak tissue concentration, and time of peak tissue concentration were determined. Half-life of CEF, SMM, SQ, OLA, PEN, ALB, and two metabolites of ALB (sulfoxide and sulfone) in various tissues ranged 0.6-1.4, 4.7-9.0, 4.5-18.9, 1.8-3.1, 0.9-3.0, 3.4-9.6, 5.0-16.1 and 7.4-12.2 h. The times required for CEF, SMM, SQ, OLA, PEN, and ALB residue concentrations to decline to 0.1 microgram/g in various tissues ranged from 5.0-11.6, 70.0-110.5, 114.0-179.8, 21.3-30.3, 4.1-24.8 and 47.8-84.4 h. Drug kinetic characteristics in tissues differed significantly from those in plasma, and also varied from tissue to tissue. It is necessary, therefore, to evaluate tissue kinetics when designing dosage regimens in tissue infection chemotherapy with these drugs. Knowledge of tissue kinetics is also important in predicting and controlling drug residues in edible tissues of food-producing animals.

Role of protein phosphatase 2A in the control of glycogen metabolism in yeast.

The yeast homologues of mammalian protein phosphatase 2A (PP2A) are encoded by two genes, PPH21 and PPH22. To evaluate the role of these phosphatases in the control of glycogen metabolism, wild-type cells and mutants carrying deletions of PPH21 or PPH22 were studied. Our results indicate that the lack of a single gene product does not result in significant changes in glycogen content, glycogen synthase, and glycogen phosphorylase activities. Since the double disruption is very detrimental to the cell, the effect of lack of PP2A was evaluated by using strain H336, which carries a deletion of the PPH21 gene and has the PPH22 gene placed under the control of the GAL1 promoter, under conditions that allowed either progressive depletion or overexpression of PPH22. When grown on galactose, H336 cells contain 2-3-fold more PP2A activity than control cells. After 14 h in glucose, however, PP2A activity in strain H336 is markedly reduced. The decrease in PP2A activity correlates with a reduced accumulation of glycogen and a more pronounced inactivation of glycogen synthase while glycogen phosphorylase becomes more resistant to inactivation. These observations suggest a role for PP2A in controlling the activation states of both enzymes. The total amount of phosphorylase was also higher in the PP2A-depleted cells, as determined by both enzymic and immunochemical techniques. However, Northern-blot analysis revealed that this is not due to an increase in the phosphorylase mRNA, which is in fact reduced in these cells. In contrast, overexpression of PP2A causes an increased expression of glycogen phosphorylase and a resulting failure to accumulate glycogen. We conclude that PP2A is involved in regulating both the amounts and the activation states of glycogen synthase and glycogen phosphorylase.

Yeast BTF3 protein is encoded by duplicated genes and inhibits the expression of some genes in vivo.

BTF3 is a human protein that is thought to be involved in transcription by RNA polymerase II [Zheng et al., Cell 50, 361-368, 1987]. A yeast homologue of BTF3, Egd1p, has been identified by its ability to enhance DNA binding of the Gal4p activator [Parthun et al., Mol. Cell. Biol. 12, 5683-5689, 1992]. We have cloned a second yeast gene, BTT1, which also encodes a BTF3 homologue. Btt1p and Egd1p are highly similar in sequence, which suggests that they are duplicated proteins with similar functions. Gene disruptions were used to investigate the function of the two proteins. Consistent with published results, we found that loss of EGD1 causes a minor defect in GAL gene induction. Loss of BTT1 has little if any effect. Surprisingly, we found that cells which lack both genes instead express the GAL1 and GAL10 mRNAs at much higher levels than wild type cells. This suggests that BTF3 really plays a negative role in GAL gene expression. Further experiments revealed that expression of the ACT1 and SSO1 genes also is elevated in cells that lack EGD1 and BTT1. In contrast, expression of rRNA and tRNA was not affected. We conclude that Btt1p and Egd1p have redundant functions in vivo, and that they exert a negative effect on the expression of several genes that are transcribed by RNA polymerase II.

Overexpression of yeast PAM1 gene permits survival without protein phosphatase 2A and induces a filamentous phenotype.

Protein phosphatase 2A (PP2A) is an essential enzyme which is present in all eukaryotic cells. PP2A has been implicated in regulating various metabolic processes and also in the control of cell cycle progression. In the yeast Saccharomyces cerevisiae, the catalytic subunit of PP2A is encoded by two duplicated genes, PPH21 and PPH22. A third related gene, PPH3, also contributes some PP2A activity. We have used a yeast strain in which a single functional PP2A gene is expressed from a regulated promoter to screen for high copy number suppressors of PP2A depletion. A new gene was cloned, PAM1 (PP2A multicopy suppressor), which in high copy number can bypass the need for a PP2A catalytic subunit. The PAM1 gene encodes a hydrophilic 93-kDa protein that contains two coiled coil motifs and has a highly basic C-terminal tail. High level overexpression of PAM1 inhibits growth and induces a filamentous phenotype.

Protein phosphatase 2A in Saccharomyces cerevisiae: effects on cell growth and bud morphogenesis.

We have cloned three genes for protein phosphatases in the yeast Saccharomyces cerevisiae. Two of the genes, PPH21 and PPH22, encode highly similar proteins that are homologs of the mammalian protein phosphatase 2A (PP2A), while the third gene, PPH3, encodes a new PP2A-related protein. Disruptions of either PPH21 or PPH22 had no effects, but spores disrupted for both genes produced very small colonies with few surviving cells. We conclude that PP2A performs an important function in yeast cells. A disruption of the third gene, PPH3, did not in itself affect growth, but it completely prevented growth of spores disrupted for both PPH21 and PPH22. Thus, PPH3 provides some PP2A-complementing activity which allows for a limited growth of PP2A-deficient cells. Strains were constructed in which we could study the phenotypes caused by either excess PP2A or total PP2A depletion. We found that the level of PP2A activity has dramatic effects on cell shape. PP2A-depleted cells develop an abnormal pear-shaped morphology which is particularly pronounced in the growing bud. In contrast, overexpression of PP2A produces more elongated cells, and high-level overexpression causes a balloonlike phenotype with huge swollen cells filled by large vacuoles.

Formation of lymphocyte colonies under serum-free culture conditions in normal individuals and patients with chronic lymphocytic leukemia.

This paper describes a culture system which supports the formation of B cell and some T cell colonies under serum-free conditions in peripheral blood samples of normal individuals and patients with chronic lymphocytic leukemia (CLL) of B cell type. In this system, serum is replaced by bovine serum albumin, transferrin, cholesterol, insulin and catalase or horseradish peroxidase. In addition, it is necessary to add staphylococcus protein A, mitomycin-treated T cells as feeders and phytohemagglutinin leukocyte-conditioned medium as a source of growth factors. The plating efficiency is greatly enhanced when normal cells are incubated with galactose oxidase prior to plating and when CLL cells are exposed sequentially to neuraminidase and galactose oxidase.