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A selective and sensitive ultra-performance liquid chromatography–electrospray ionization tandem mass spectrometry (UPLC–MS) method was developed for the simultaneous determination of ten biogenic amines (tryptamine, 2-phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine, adrenaline, dopamine and spermine) in a thymopolypeptides injection from the Chinese market for the first time. Biogenic amines (BAs) were pre-column derivatised by dansyl chloride after direct sample dilution. Dansylated amines were separated on an ACQUITY UPLC BEH Shield RP18 column (2.1 mm × 150 mm I.D., 1.7 μm) using a gradient elution. Quantification was done by monitoring fragment ions of each derivative under the MS mode of multiple reaction monitoring (MRM). A satisfactory result of method validation was obtained. The linearity ranged from 0.32 to 1182.9 μg/L and the correlation coefficients ( r ) for all amines were above 0.99. The LOD ranged from 0.08 μg/L for 2-phenylethylamine and tyramine to 8.00 μg/L for adrenaline; the LOQ ranged from 0.32 μg/L for 2-phenylethylamine to 12.12 μg/L for dopamine. The recovery ranged from 75.8 to 110.3% after spiking standard solutions of BAs to a sample at three levels. The intra and inter-day precision RSD were 0.78–8.85% and 1.39–9.93% respectively. Eighty-four injections were analyzed by this method. Nine biogenic amines were found in them except adrenaline. Moreover, the relationship between the result of test for depressor substances and the content of BAs was statistically analyzed.

Objective To identify the risk factors for imipenem resistance development and transmission of clinical Pseudomonas aeruginosa isolates. Methods Thirty-seven imipenem unsusceptible Pseudomonas aeruginosa isolates collected from patients in absence of carbapenem treatment were characterized by antimicrobial susceptibility test, pulsed field gel electrophoresis (PFGE) and carbapenem resistant mechanism analysis. Results Before the collection of imipenem unsusceptible Pseudomonas aeruginosa isolates, the average time of patients treated with more than one antimicrobial (20.0 ± 9.5 days, n = 16) was significantly longer than those treated with only one antimicrobial (12.6 ± 4.4 days, n = 21; t-test, Welch, t = -2.9004, P < 0.01). And 32 isolates showed resistance to more than 3 classes of antimicrobials. Six PFGE clusters were identified and 26 isolates were grouped into one dominant cluster (C2). An ISpa1328 sequence insertion in oprD was detected in 33 isolates and the function of efflux was observed in all 37 isolates in the presence of a wide spectrum efflux inhibitor. Conclusions Our data demonstrated that exposure to non-carbapenem drug classes, especially fluoroquinolones and β-lactams, may be important risk factors for the spread of carbapenem resistant Pseudomonas aeruginosa.

Gambogic acid (1) is a cytotoxic caged xanthone derived from the resin of Garcinia hanburyi. Compound 1 selectively induces apoptosis in cancer cells, at least partially, by targeting the stress response to reactive oxygen species (ROS). However, the molecular mechanism of ROS toxicity stimulated by 1 remains poorly understood. In this study, mass spectrometric and biochemical pharmacological approaches were used that resulted in the identification of both cytosolic thioredoxin (TRX-1) and mitochondrial thioredoxin (TRX-2) as the molecular targets of 1. The results obtained showed that 1 deactivates TRX-1/2 proteins by covalent binding to the active cysteine residues in the functional domain via Michael addition reactions. Since both TRX-1 and TRX-2 play key roles in regulating the redox signaling of cancer cells, the present findings may shed light on the relationship between protein binding and cellular ROS accumulation induced by 1. This provides support for the current clinical trials of gambogic acid (1) being conducted alone or in combination with other agents that appear to increase ROS generation in order to selectively kill cancer cells.

Although the anticancer activities of the resin of Garcinia hanburyi have been well demonstrated, the chemical composition of this medicinal plant is still not fully understood. In this study, a highly effective qualitative method was developed for rapidly profiling the target and non-target caged xanthones in the resin of G. hanburyi. This method mainly involves three steps as follows: (1) prediction of the possible unknown caged xanthones in the resin of G. hanburyi according to the structure characters of the known ones and some well established biosynthetic knowledge; (2) structure classification according to the diagnostic fragment ions (DFIs) of the known caged Garcinia xanthones; (3) detection and characterization of the target and non-target caged xanthones in the resin of G. hanburyi using multiple mass spectrometric (MS) scanning modes. By use of such procedures, mass spectrometric data can be used for confirming the rationally predicted chemical structure rather than sophisticated and time-consumed de novo structure elucidation of a completely unknown component. Finally, a total of 34 caged xanthones including 18 likely new ones from the resin of G. hanburyi were rapidly detected and characterized within one working day.

Recent studies have reported that Escherichia coli in fecal samples of healthy humans could also serve as important reservoirs of drug-resistant bacteria. Limited data are available for E. coli-resistant profiles of healthy food handlers in hospitals who provide food service to inpatients and hospital staffs. E. coli isolates were recovered from hospital healthy food handlers, and one random selected isolate from each food handler was subjected to antimicrobial susceptibility testing, phylogenetic typing, and screening for antimicrobial-resistant mechanisms by polymerase chain reaction amplification. Ciprofloxacin-resistant isolates were further characterized by mutation analysis in the quinolone resistance determining regions (QRDRs) of GyrA and ParC. And extended-spectrum β-lactamase (ESBL) producing isolates were screened for bla(CTX-M) by polymerase chain reaction amplification and DNA sequence analysis. In total, more than 50% (47/92) of E. coli isolates from healthy food handlers showed multidrug-resistant profiles and 50% (46/92) isolates carried intI. Resistance prevalence of the B2 phylogenetic group was significantly lower than that of the non-B2 groups for all tested antimicrobials (p0.05) except chloramphenicol and tetracycline. Seven isolates of phylogenetic group A (n = 3) and D (n = 4) produced ESBL, and 12 isolates of phylogenetic group A (n = 5), B2 (n = 2), and D (n = 5) were resistant to ciprofloxacin. Transferable quinolone resistance determinants were identified in four isolates. Point mutations in QRDRs of GyrA or ParC were identified among 59 out of 62 E. coli isolates showing decreased susceptibility or resistance to ciprofloxacin. Genes encoding CTX-M enzyme were identified in seven ESBL-producing isolates. The preponderance in hospital food handlers of multidrug-resistant E. coli makes it important to introduce control measures such as improved biosecurity to ensure that they do not pass through the food service and limit inpatient therapeutic options.

Gambogic acid (GA) is a promising natural anticancer candidate. Although the anticancer activity of GA has been well demonstrated, information regarding the metabolic fate of GA is limited. Previous studies suggested that GA is mainly excreted into intestinal tract in rats through bile after intravenous administration, whereas only traces appeared in the feces, suggesting that GA is metabolized extensively in the intestine. However, there has been no report about the intestinal metabolism of GA either in animals or humans. In this study, large amounts of two sulfonic acid metabolites of GA were found in the feces samples of rats after intravenous administration, and their structures were identified as 10-α sulfonic acid GA and 10-β sulfonic acid GA by comparison of the retention times and spectral data with those of synthesized reference substances using liquid chromatography-diode array detector-tandem mass spectrometry. This rare intestinal metabolic pathway mainly involves Michael addition of the sulfite ion to the 9,10 carbon-carbon double bond of α,β-unsaturated ketone. In addition, a more detailed metabolic profile in rats is proposed, according to the results of in vitro and in vivo studies. It was found that GA can be metabolized by a variety of routes, including monooxidation, hydration, glutathionylation, glucuronidation, and glucosidation in the liver of rats. These findings provide information on the major metabolic soft spot of GA in the intestine and liver of rats, which is not only useful in the future human metabolic study of this compound but also of value in the metabolic studies of GA analogs.

The objective of this study was to investigate the distribution of extended spectrum β-lactamase (ESBL)-producing Escherichia coli isolates in swine and poultry farms in China. Rectal or cloaca swabs of swine and chicken were collected from four province-level regions of China, and E. coli isolates were recovered and tested for antimicrobial susceptibility. The isolates producing ESBLs were further characterized by pulsed-field gel electrophoresis (PFGE) and sequence analysis of genes encoding β -lactamases and class I integrons. In total, 156 and 224 E. coli isolates were recovered from rectal swabs of four swine farms and cloaca swabs of six chicken farms, respectively. Prevalence of resistant isolates was higher in chicken than in swine. Fifty-six isolates producing ESBLs were identified from chicken samples, but no ESBL-producing isolates were identified from swine samples. Of 56 ESBL-producing isolates, 54 isolates contained cefotaxime (CTX)-M type β-lactamases, including bla(CTX-M-14) (n = 24), bla(CTX-M-65) (n = 13), bla(CTX-M-55) (n = 10), bla(CTX-M-24) (n = 3), bla(CTX-M-3) (n = 2), bla(CTX-M-15) (n = 1), and bla(CTX-M-64) (n = 1). Among 54 E. coli isolates containing bla(CTX-M), 11 PFGE clusters and 42 PFGE patterns were identified. More importantly, more than three-fourth of the ESBL-producing isolates in chicken were also resistant to ciprofloxacin. Our data demonstrated that chicken had become an important reservoir of bla(CTX-M) in China. Detailed molecular comparison of plasmids and genomes of isolates from various sources will help to better define the transmission dynamics of bla(CTX-M) between humans and food-producing animals.

Gambogic acid (GA), a promising anticancer candidate, is a polyprenylated xanthone abundant in the resin of Garcinia morella and Garcinia hanburyi. The major circulating metabolite of GA in human, 10-hydroxygambogic acid (10-OHGA), was identified by comparison of the retention time and mass spectra with those of reference standard using liquid chromatography-tandem mass spectrometry. The reference standard of 10-OHGA was isolated from bile samples of rats after intravenous injection of GA injection, and its structure was confirmed by NMR. Then, a selective and sensitive method was developed for the quantitative determination of this metabolite in human plasma. After liquid-liquid extraction by ethyl acetate, the analyte and the internal standard were separated on a Sepax HPC18 column (100 mm x 2.1 mm i.d., 3.0 microm) with a mobile phase of 10mM ammonium acetate water solution containing 0.1% formic acid-acetonitrile (20:80, v/v). The detection was performed on a single quadrupole mass spectrometer equipped with electrospray ionization (ESI) source. The calibration curve was linear over the range of 3-2000 ng/mL for 10-OHGA. The developed quantification method can now be used for the pharmacokinetic and pharmacological studies of 10-OHGA after intravenous infusion of GA injection in human.

Gambogic acid (GA), a promising anticancer candidate, is a polyprenylated xanthone abundant in the resin of Garcinia morella and Garcinia hanburyi. Electron capture–atmospheric pressure chemical ionization (EC-APCI) and electrospray ionization (ESI) techniques, both in the negative ion mode, were evaluated regarding ionization, fragmentation patterns and sensitivity for simultaneous liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of GA and its main circulating metabolite, 10-hydroxygambogic acid (10-OHGA) in dog plasma. Both analytes underwent extensive in-source fragmentation in EC-APCI, which was not desirable for reliable quantification of these analytes, whereas the substitution of ESI for EC-APCI almost eliminated the source instability of both analytes. Negative ion ESI was, therefore, chosen for the development of an LC-MS/MS method for simultaneous determination of these analytes. After protein precipitation by acetonitrile, all analytes were separated on a Luna C18 HST column (50 × 2.0 mm i.d., 2.5 μm) with a mobile phase of 20 mmol L−1 ammonium acetate water solution containing 0.2% acetic acid: acetonitrile (18:82, v/v). The detection was performed on a tandem mass spectrometer using selective reaction monitoring mode. Calibration curves were linear over the range of 10–6000 ng mL−1 for GA and 3–2000 ng mL−1 for 10-OHGA. The method was successfully applied to the pharmacokinetics study of GA injection in six beagle dogs.

Detailed structures of N-linked oligosaccharides of Defibrase, a highly active thrombin like enzyme (TLE) purified from the venom of Agkistrodon acutus, were successfully characterized using MALDI-TOF mass spectrometry in combination with sequential exoglycosidase digestion. Monosaccharide composition analysis was performed by high performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Galactose(Gal), mannose(Man), fucose(Fuc), N-acetylglucosamine (GlcNAc), and sialic acid (Neu5Ac) was detected and the total carbohydrate content was about 19.4% (w/w). The N-linked oligosaccharides were released by treatment with PNGase F, fluorescent labeled with 2-aminobenzamide, and fractionated by high performance liquid chromatography (HPLC). The main oligosaccharide fractions were collected and further digested with an array of exoglycosidase mixtures, and subsequent MALDI TOF MS analysis of the resulting products yielded information about structural features of the oligosaccharide. The combined data revealed the presence of five distinct oligosaccharide structures in Defibrase, which are mainly complex or hybrid type, with a small amount of oligomannosidic type. The complex type oligosaccharides are mostly tri-or bi-antennary and the hybrid oligosaccharides are all bi-antennary. Most oligosaccharides are also found to be fucosylated.

Background The categories of recognized transferable quinolone resistance determinants have been increasing sharply. The rapid horizontal transfer of these quinolone resistance genes has caused concern since they bring new dissemination possibilities for quinolone resistance. Methods In total, 579 clinical Escherichia coli isolates were subjected to antimicrobial susceptibility testing, screening for qnr alleles, qepA and aac-(6')-Ib-cr by PCR amplification and DNA sequence analysis. Isolates containing transferable quinolone resistance determinants were further characterized by mutation analysis in the quinolone resistance determining regions (QRDRs) of GyrA and ParC, phylogenetic typing and PFGE to determine their genetic relatedness. Results After PCR screening and sequence analysis, transferable quinolone resistance determinants were identified in 74 of 579 E. coli isolates (12.8%). The antimicrobial resistance profiles and phylogenetic groups differed between isolates containing different categories of transferable quinolone resistance determinant. Most of the isolates containing qepA alone were highly resistant to ciprofloxacin (MIC >or= 512 mg/L) and belonged to phylogenetic group D (22/25), while most of the isolates containing aac-(6')-Ib-cr alone belonged to phylogenetic group A (17/35) or D (16/35). Of 74 E. coli isolates containing transferable quinolone resistance determinants, 69 PFGE patterns and 19 clusters were identified. Conclusions The great genetic variation of E. coli hosts containing transferable quinolone resistance determinants demonstrated the high transmission capacity of these mechanisms. It is urgent to characterize and block their transmission routes in order that the utility of quinolones is preserved.

The soil-bag has the large bearing capacity to the external force, because the materials inside soil-bags are wrapped and confined completely by the bag. In this study, the compression tests and cyclic shear tests were performed to evaluate the mechanical characteristics of the soil-bags for the design of the reinforcement soil by bags. As the results, the experimental compression baring loads almost agree with the theoretical values and the characteristics of the high performance hysteresis damping of the piled up soil-bags were found out.

A sensitive LC method with pre-column fluorescence derivatization using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate has been developed for the determination of defibrase from the venom of Agkistrodon acutus (also named defibrase in the Chinese Pharmacopoeia) in pharmaceutical formulation. By a denaturing procedure prior to derivatization, full and homogeneously derivatization of defibrase was obtained and demonstrated using MALDI-TOF-MS. The specificity of the method was validated by assessing interference from the placebo and by forced degradation. The method has demonstrated good linearity (r = 0.9998), accuracy (mean recovery 98.53%) and precision (RSD

A rapid and sensitive method for determination of methyl nonyl ketone in rat plasma was developed based on GC–MS. The analyte and internal standard, propyl p-hydroxybenaoate, were extracted from plasma with methyl tert-butyl ether and then separated by an HP-5MS capillary analytical column (30 m × 0.25 mm, 0.25 µm) and determined by a quadrupole mass spectrometer detector operated under EI ionization and selected ion monitoring mode. Excellent linearity was found to be from 5.0 to 1,000 ng mL−1 with a lower limit of quantitation of 5.0 ng mL−1. The accuracy was between 96.0 and 106.3%, and the intra- and inter-day precision and accuracy values were found to be within the assay variability criteria limits according to the FDA guidelines. The developed method was successfully applied to the pharmacokinetic study of methyl nonyl ketone, a typical component in the traditional Chinese medicine Houttuynia cordata injection, in rats after a single oral dose of 100 mg kg−1 and peritoneal injection dose of 5 mg kg−1, respectively.

Salmonella enterica isolates recovered from stool samples of healthy food handlers in two hospital dining halls in Beijing, China were characterized by serotyping, susceptibility to 15 antimicrobials and pulsed field gel electrophoresis (PFGE). Our data showed that 9.5% (29/305) of food handlers in these two dining halls were Salmonella carriers. Twenty-nine isolates were grouped into five serotypes including Agona, Derby, Enteritidis, Infantis and Senftenberg. All six Enteritidis isolates were resistant to chloramphenicol, nalidixic acid and tetracycline. Identical PFGE patterns were identified from food handlers in the same dining hall that indicated the possible transmission of Salmonella among food handlers and to customers. Our findings underscore the importance of food hygiene education and regular health examination among food handlers in dining halls in China. PRACTICAL APPLICATIONS Food handlers in dining halls should be considered as a high-risk group for Salmonella carrier state in China. Food hygiene education and regular health examination among food handlers in dining halls should be carried out.

With the rapid growth of the dairy industry and the establishment of strict antimicrobial residue limits in the People's Republic of China's (PRC) milk supply, a -lactamase product known as antimicrobial destroyer was introduced into dairy production without regulatory review. We developed a method for detecting this product in milk samples based on a modified cylinder plate method. The presence of -lactamase is defined as a difference between the inhibitory zones of the test samples (supplemented with 25 g/mL sulbactam plus 0.5 g/mL penicillin G) and control samples (supplemented only with 0.5 g/mL penicillin G) 3 mm. Using this method, 77 individually packaged milk samples were randomly collected from 5 retail stores in 3 cities over a 4-month period (May to August 2006). Of the 77 samples, 49 were found to be -lactamase-positive. In 2 undiluted milk samples showing extremely high -lactamase activity, 25 g/mL sulbactam could not inhibit penicillin G activity. Because there is a lack of safety data on -lactamases in milk products, these data indicated a potentially serious safety concern for the dairy industry in the PRC.

Salmonellae are a common cause of community-acquired foodborne bacterial gastroenteritis worldwide. The incidence of Salmonella infections in the People’s Republic of China has not been well documented. However, in the United States, ≈1.4 million persons are infected by Salmonella spp. each year (1). Although >2,500 serotypes have been reported, Salmonella enterica serotype Typhimurium is 1 of the leading serotypes causing salmonellosis worldwide (2). Fluoroquinolones such as ciprofloxacin are strongly recommended for treatment of severe S. Typhimurium infections in adults (3). In this study, we characterized all S. Typhimurium isolates recovered from May 2002 through October 2005 from outpatients of Tongji Hospital, Wuhan, China, a sentinel hospital in the National Center for Surveillance of Antimicrobial Resistance. During the time of this study, Tongji Hospital strictly followed the recommendation for treatment of severe S. Typhimurium infections.

To evaluate the prevalence of antimicrobial resistance and selected antimicrobial resistance mechanisms in Shigella isolates recovered in outpatients from 1997 to 2009 in China.The isolates were subjected to serotyping and antimicrobial susceptibility testing. Shigella isolates producing extended-spectrum β-lactamases (ESBLs) or resistance to ciprofloxacin were further characterized by PFGE to determine the genetic relatedness. These isolates were also screened for β-lactamase genes and mutations in the quinolone resistance-determining regions (QRDRs) by PCR. DNA sequence analysis was also performed.After serotyping, 301 Shigella isolates were grouped into three subgroups and 13 distinct serotypes. The antimicrobial resistance profiles differed among subgroups and serotypes. Ciprofloxacin-resistant isolates were mainly Shigella flexneri serotypes f2a and f4a, which were resistant to at least four additional non-quinolone antimicrobials. Three point mutations in the QRDRs of gyrA and parC were identified in all 30 ciprofloxacin-resistant S. flexneri isolates. Plasmid-mediated bla(CMY-2), bla(CTX-M-14), bla(CTX-M-15) and bla(CTX-M-55)-like genes were found in 29 ESBL-producing isolates and three clavulanic-acid-resistant isolates, and six isolates also exhibited resistance to ciprofloxacin. Distinct genetic differences in both serotypes and PFGE profiles were observed for these ciprofloxacin- or extended-spectrum-cephalosporin-resistant isolates.ESBL-producing or fluoroquinolone-resistant Shigella is no longer an unusual phenomenon in the local community. The monitoring programme in China should stay vigilant to the dissemination of these isolates and the health agencies must take appropriate measures to restrict the abuse of antimicrobials, especially in the community.

Alterations in topoisomerases and plasmid-mediated quinolone-resistant (PMQR) determinants have been identified as main quinolone-resistant mechanisms in Salmonella enterica Typhimurium. But the joint effects of these mechanisms have not been thoroughly characterized in homologous Salmonella Typhimurium strains. In this study, isogenic topoisomerase mutants were constructed using phage λ Red recombinase system and phage transduction. And the joint effects of topoisomerase mutations (gyrA [S83F], gyrA [S83F, D87N] and parC [S80I]) and PMQR determinants (including qnrB4, qnrS1, aac(6')-Ib-cr, and qepA) were studied in homologous genetic constitutions. Our data showed that mutations in gyrA played a dominant role in fluoroquinolone resistance in Salmonella Typhimurium and have a synergistic effect with other resistant mechanisms. The mutation (S80I) in parC would have no effect in quinolone resistance without gyrA mutations. The joint effect of aac(6')-Ib-cr and topoisomerase mutations were only observed for ciprofloxacin among tested quinolones. Different joint effects between topoisomerase mutations and qepA, qnrB4, or qnrS1 were observed for tested quinolones. Importantly, the acquirement of the PMQR determinants could improve 0- to 32-fold of the host mutant prevention concentration to ciprofloxacin. Our data showed that the acquirement of PMQR determinants could not only improve the host minimal inhibitory concentrations to quinolones but also accelerate the generation of high-level fluoroquinolone-resistant mutants.

Extended-spectrum cephalosporins and fluoroquinolones are important antimicrobials for treating invasive salmonellosis, and emerging resistance to these antimicrobials is of paramount concern. This study reports on the antimicrobial susceptibility and molecular characterization of Salmonella enterica isolates recovered in 2006 from 0- to 3-year-old outpatients in China.The isolates were subjected to serotyping, antimicrobial susceptibility testing, screening for beta-lactamase genes, mutations in the quinolone resistance determining regions (QRDRs), qnr alleles and aac-(6')-Ib-cr by PCR followed by DNA sequence analysis. All Salmonella Typhimurium isolates and 43 selected non-Typhimurium isolates were further characterized by PFGE to determine the genetic relatedness.From 3746 paediatric outpatient stool samples, 221 (5.9%) S. enterica isolates of 29 distinct serotypes were recovered. The antimicrobial resistance profiles differed among serotypes. Ciprofloxacin-resistant isolates were concentrated in serotype Typhimurium that were resistant to at least four additional non-quinolone antimicrobials. Nineteen out of 22 ciprofloxacin-resistant Salmonella Typhimurium isolates were grouped into one PFGE cluster. Plasmid-mediated quinolone resistance determinant aac-(6')-Ib-cr was detected in 18 S. enterica isolates and 4 isolates also carried qnr alleles. Plasmid-mediated blaCTX-M-14-like genes were found in seven ceftriaxone-resistant isolates, and two isolates also exhibited reduced susceptibility to ciprofloxacin.Based on these results, fluoroquinolones should not be used to treat the invasive Salmonella Typhimurium infections in this local community. The monitoring programme should stay vigilant for ceftriaxone-resistant S. enterica isolates with reduced fluoroquinolone susceptibility.

With the rapid growth of the dairy industry and the establishment of strict antimicrobial residue limits in the People's Republic of China's (PRC) milk supply, a beta-lactamase product known as "antimicrobial destroyer" was introduced into dairy production without regulatory review. We developed a method for detecting this product in milk samples based on a modified cylinder plate method. The presence of beta-lactamase is defined as a difference between the inhibitory zones of the test samples (supplemented with 25 microg/mL sulbactam plus 0.5 microg/mL penicillin G) and control samples (supplemented only with 0.5 microg/mL penicillin G)or = 3 mm. Using this method, 77 individually packaged milk samples were randomly collected from 5 retail stores in 3 cities over a 4-month period (May to August 2006). Of the 77 samples, 49 were found to be beta-lactamase-positive. In 2 undiluted milk samples showing extremely high beta-lactamase activity, 25 microg/mL sulbactam could not inhibit penicillin G activity. Because there is a lack of safety data on beta-lactamases in milk products, these data indicated a potentially serious safety concern for the dairy industry in the PRC.

An unknown impurity named amphotericin B (2) (AmB(2)) isolated from amphotericin B (AmB) bulk material was identified as (1S,3S,5R,6R,9R,11R,15S,16R,17R,18S,19E,21E,23E,25E,27E,29E,31E,33R,35S,36R,37S)-33-[(3-amino-3,6-dideoxy-beta-D-mannopyranosyl)oxy]-1-methyloxy-3,5,6,9,11,17,37-heptahydroxy-15,16,18-trimethyl-13-oxo-14,39-dioxabicyclo[33.3.1]nonatriaconta-19,21,23,25,27,29,31-heptaene-36-carboxylic acid according to the IUPAC. The structure was elucidated by various 1D and 2D NMR techniques, mass spectrometry and by comparison with the NMR data of AmB. Its activity against Candida albicans was evaluated by comparison with AmB.

The distinction of antimicrobial resistance of clinical bacteria isolated from county hospitals and a teaching hospital was investigated. Disc diffusion test was used to study the antimicrobial resistance of isolates collected from county hospitals and a teaching hospital. The data was analyzed by WHONET5 and SPSS statistic software. A total of 655 strains and 1682 strains were collected from county hospitals and a teaching hospital, respectively, in the year of 2003. The top ten pathogens were Coagulase negative staphylococci (CNS), E. coli, Klebsiella spp., S. areus, P. aeruginosa, Enterococcus spp., Enterobacter spp., otherwise Salmonella spp., Proteus spp., Shigella spp. in county hospitals and Streptococcus spp., Acinetobacter spp., X. maltophilia in the teaching hospital. The prevalence of multi-drug resistant bacteria was 5% (4/86) of methicillin-resistant S. areus (MRSA), 12% (16/133) and 15.8% (9/57) of extended-spectrum beta-lactamases producing strains of E. coli and Klebsiella spp., respectively, in county hospitals. All of the three rates were lower than that in the teaching hospital and the difference was statistically significant (P0. 01). However, the incidence of methicillin-resistant CNS (MRCNS) reached to 70% (109/156) in the two classes of hospitals. Generally, the antimicrobial resistant rates in the county hospitals were lower than those in the teaching hospital, except the resistant rates of ciprofloxacin, erythromycin, clindamycin, SMZco which were similar in the two classes of hospitals. There were differences between county hospitals and the teaching hospital in the distribution of clinical isolates and prevalence of antimicrobial resistance. It was the basis of rational use of antimicrobial agents to monitor antimicrobial resistance by each hospital.

To determine the shift of susceptibility of methicillin-resistant Staphylococcus aureus (MRSA) isolates to vancomycin in recent years.Antimicrobial susceptibility was determined by disk diffusion test (K-B method). The t-test was used to compare the mean diameters of zone of inhibition.The clinical isolates of MRSA from 1994 to 2000 were 218, 187, 292, 237, 351, 886 and 652 in number respectively. The mean diameters (mm) of the inhibition zone of MRSA isolates each year were 19.9, 19.1, 18.6, 17.4, 18.4, 18.2 and 17.8. Comparison of the diameters of the inhibition zone of MRSA isolates (K-B method) showed that the mean diameter of the inhibition zone from the 652 MRSA isolates in 2000 was much less than that of the 218 MRSA isolates in 1994 and the difference was significant (P0.001). The resistant rates to chloramphenicol, ciprofloxacin, erythromycin, gentamicin, tetracycline and trimethoprim/sulfamethoxazole were 44.0%, 73.7%, 89.1%, 65.7%, 61.0% and 67.0%.Our observation demonstrated that the susceptibility of MRSA to vancomycin gradually decreased from 1994 to 2000. It is important to monitor the antimicrobial susceptibility of Staphylococcus aureus to vancomycin.