[Pathogen Diagnosis of a Febrile HIV Case by the Metagenomic Next-generation Sequencing].

This study is aimed to explore the value of metagenomic next-generation sequencing (mNGS) in diagnosing pathogen in fever patients. It is often a challenge to identify the pathogen that caused the infection in the HIV patients with fever. How could the mNGS be helpful for pathogen diagnosis is unclear. Here we reported a case of human immunodeficiency virus (HIV) patient with 2-month period of fever. After routine clinical laboratory tests including the conventional smear, culture, serological tests and pathological examinations, the causal pathogen still remained undiagnosed. Then the lymph node biopsy tissue was subjected to broad-range polymerase chain reaction (PCR) and the peripheral blood was subjected to mNGS. At the same time, peripheral blood culture was carried out with an extension of culture time to acquire the pathogen. Results from both broad-range PCR and mNGS revealed the pathogen was Talaromyces marneffei. The isolate recovered from the peripheral blood culture was subjected to the whole-genome sequencing. Whole genome sequencing revealed that the antimicrobial resistance gene FLU1 existed in this pathogen's genome, but mNGS did not detect the FLU1 gene. Phylogenetic analysis based on whole genome sequence revealed that this isolate was far from other clones published in NCBI database. Here we reported a case of Talaromyces marneffei infection diagnosed by mNGS, showing that mNGS is helpful in etiological diagnosis for HIV patients with unexplained fever. However, application of mNGS in antimicrobial resistant genes detection and pathogen tracing need to be well-studied in the future.

Rapid and visual detection for hypochlorite of an AIE enhanced fluorescence probe.

In this paper, a new 'turn-on' fluorescence probe for the rapid, sensitive, and visual detection of hypochlorite is reported. The push-pull type trianiline-tricyanofuran-based fluorescent probe was prepared using a condensation reaction between tricyanofuran and the thiophene-trianiline derivative that had high quantum yields and showed aggregation-induced emission enhanced properties. Upon exposure to hypochlorite, prominent fluorescence enhancement of the probe was observed via the release of the fluorophore from the probe. The probe showed a ratiometric absorption change at 315 nm and 575 nm. Importantly, the probe showed an excellent detection limit for hypochlorite at 1.2 × 10-7  M in solution and it was successfully applied for monitoring hypochlorite in waste water by test strip. This work reports a new fluorescence analytical sensing method for hypochlorite that has potential practical value in environmental monitoring and biological discrimination.

Two-channel near-infrared fluorescence Ag+ ion sensing of a new star-shaped dendrimer.

A new near-infrared fluorescence sensor PDI-PD for Ag+ ions was successfully prepared and its structure characterized by 1 H nuclear magnetic resonance (NMR), 13 C NMR and high-resolution mass spectrometry; matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (HRMS MALDI-TOF). The probe exhibited rapid, sensitive, and selective two-channel fluorescence responses towards Ag+ ions and protons. The probe has a marked high binding affinity and high sensitivity for Ag+ , with a detection limit of 1.4 × 10-6  M. An approximately five-fold enhanced core emission at 784 nm was attributed to fluorescence resonance energy transfer (FRET). The enhanced core emission of the probe with Ag+ ions based on photo-induced electron transfer and FRET is discussed. In addition, the probe presented a visible colour change. All experimental results demonstrated that PDI-PD is an efficient tool for the selective, sensitive and rapid detection of Ag+ ions and protons using two-channel fluorescence responses.

Gracilibacillus eburneus sp.nov., a moderately halophilic bacterium isolated from Xinjiang province, China.

A novel Gram-staining positive, moderately halophilic, endospore-forming, motile, rod-shaped and strictly aerobic strain, designated YIM 93565T, was isolated from a salt lake in Xinjiang province of China and subjected to a polyphasic taxonomic study. Strain YIM 93565T grew in the range of pH 6.0-9.0 (optimum pH 7.0), 10-45 °C (optimum 35-40 °C) and at salinities of 2-24% (w/v) NaCl (optimum 7-10%). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain YIM 93565T clustered with members of the genera Gracilibacillus and form a clade with Gracilibacillus bigeumensis KCTC 13130T (95.6% similarity) and Gracilibacillus halophilus DSM 17856T (94.9%), which was well separated from others. The DNA G + C content of this novel strain was 36.8 mol%. The major fatty acids were anteiso-C15:0, iso-C15:0, C16:0 and anteiso-C17:0 and its polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, one unidentified glycolipid and two unidentified phospholipids. The predominant menaquinone was MK-7. The cell-wall peptidoglycan was based on meso-diaminopimelic acid. Based on the results of phylogenetic, physiological and chemotaxonomic comparative analyses, the isolate is assigned to a novel species of the genus Gracilibacillus, for which the name Gracilibacillus eburneus sp. nov. is proposed, with the type strain YIM 93565T (= DSM 23710T = CCTCC AB 2013249T).

[Analysis of Pathogens and Clinical Characteristics in 157 Cases with Infective Endocarditis].

OBJECTIVE: To analyze the clinical characteristics of infective endocarditis (IE) in culture-positive patients,so as to provide the evidences for reasonable diagnosis and treatment of IE. METHODS: We performed a retrospective study of 157 culture-positive IE cases,which were diagnosed according to modified Duke criteria for IE from Jan. 2008 to Aug. 2015. RESULTS: The average age of 157 cases of IE was 40.85 years. One hundred and one patients (64.3%) had various underlying cardiac diseases,including congenital cardiovascular diseases in 44 cases and rheumatic heart diseases in 15 cases. The main clinical manifestations were anemia (147 cases,93.6%),fever(137 cases,87.3%) and heart murmur (120 cases,76.4%). Vegetation was found in 12 cases (7.6%) with transesophageal echocardiography (TEE) but not with transthoracic echocardiography (TTE) . Culture results showed the most common causative microorganisms were Streptococci (76 cases,48.4%),with Viridans streptococci dominated in 70 cases,and Staphylococci (33 cases,21.0%) (Staphylococcus aureus dominated in 18 cases). All patients were treated with antimicrobial agents. Eighty-five patients (54.1%) received surgical intervention,of which 72 cases received valve replacement. Twenty-seven patients were cured,88 patients were markedly improved,38 patients discontinued treatment,and 4 patients died. The therapeutic efficacy of operation group was better. CONCLUSION: The clinical characteristics of IE included: the age of onset increased,congenital heart disease was the most underlying disease,and Viridians streptococci was the most popular causative microorganism. Surgical therapy can effectively improve the outcomes of IE patients.

Skermanella rubra sp. nov., a bacterium isolated from the desert of Xinjiang, China.

A Gram-negative, pink-coloured, rod-shaped, motile bacterium, designated YIM 93097(T), was isolated from the desert soil collected from Xinjiang province of China. Strain YIM 93097(T) was found to grow at 20-45 °C (optimum 28-37 °C), pH 5.0-7.0 (optimum pH 7.0) and 0-8 % (w/v) NaCl (optimum 1 %, w/v). Based on 16S rRNA gene sequence similarity studies, it belongs to the genus Skermanella. The 16S rRNA gene sequence similarity was identified to be 98.7 % to Skermanella xinjiangensis CCTCC AB 207153(T) while the DNA-DNA hybridization value was found to be only 48.1 %. The predominant isoprenoid quinone was determined to be Q-10. The major fatty acids were identified to be C16:0, C18:1 ω7c and summed feature 4 (consisting of C17:1 anteiso B/iso I). The major polar lipids were identified as phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, two unidentified phospholipids and one unidentified aminolipid. The DNA G+C content was found to be 67.2 mol %. The analysis of the genotypic and phenotypic data indicated that strain YIM 93097(T) belongs to a novel species of the genus Skermanella, for which the name Skermanella rubra sp. nov. is proposed. The type strain is YIM 93097(T) (=DSM 21389(T)=CCTCC AB 2015161(T)).

[Analysis of resistance tendency of bloodstream-infecting pathogens in China].

OBJECTIVE: To investigate the resistance profiles and the trend of bloodstream-infecting pathogens isolated from hospitalized patients during 2004-2010. METHODS: The bloodstream isolates were collected from 18 hospitals in 17 cities. Minimum inhibition concentrations (MIC) were determined using the agar dilution method recommended by CLSI (Clinical and Laboratory Standards Institute), and susceptibility results were analyzed according to the 2011 CLSI guideline. RESULTS: Among the 2004-2005, 2007-2008 and 2009-2010 periods, the proportions of clinical isolates were similar; 43.1% (149 isolates), 34.0% (151 isolates) and 47.5% (776 isolates) for Gram positive strains, 56.9% (197 isolates), 66.0% (293 isolates) and 52.5% (858 isolates) for Gram negative strains, respectively. The isolating rate of MRSA was 54.1% (20/37) in 2007-2008, which was the highest among the 3 periods during 2004 to 2010, while it decreased in 2009-2010 (36.5%, 62/170). The MRCNS proportions were similar across the 3 periods. One (1.8%) vancomycin-resistant Enterococcus faecium and 1 linezolid-resistant Enterococcus faecalis were found. Although the isolating rates of penicillin non-sensitive strains (oral) were similar between 2009-2010 and 2007-2008 [54.5% (6/11) and 53.9% (7/13), respectively], the resistant rates increased from 0% in 2007-2008 to 30.8% (4/13) in 2009-2010. The results were similar according to the non-meningitis criterion (IV), and the susceptibility rates decreased from 100.0% (11 isolates) in 2007-2008 to 84.6% (11/13) in 2009-2010. ESBL-harboring strains in E. coli were similar among the 3 periods during 2004 to 2010 [66.7% (30/45), 73.2% (71/97) and 67.9% (233/343), respectively]. ESBL-producing strains in Klebsilla pnuemoniae decreased year after year, 72.4% (21/29), 50.0% (18/36) and 41.1% (65/158) in 2004-2005, 2007-2008 and 2009-2010, respectively. Except that the sensitive rate of Enterobacter cloacae to ertapenem was 80% (32/40), the sensitive rates of other strains to carbapenems were still above 90% and the resistance rates were less than 5%. Acinetobacter baumannii had the highest multi-drug resistance rate (81.8%, 81/99). One strain (1.0%, 1/99) of Acinetobacter baumannii isolated in 2009-2010 was reported to be pan-resistant. CONCLUSIONS: We are facing a more serious situation of bacterial resistance. Acinetobacter baumannii resistance was most serious, usually with the characteristics of multiple drug resistance, and even pan-resistance. Carbapenems remain to be the most effective against enterobacteriaceae. Strains resistant to novel antibiotics (linezolid and tigecycline) have emerged.

[Clonal relatedness of bla(OXA-58)--carrying Acinetobacter baumannii clinical isolates].

OBJECTIVE: To investigate the clonal relatedness of local bla(OXA-58)-carrying Acinetobacter baumannii clinical isolates. METHODS: Non-duplicated isolates of Acinetobacter baumannii were collected in West China Hospital and verified by recA sequencing. Acquired bla(OXA-58) gene and natural bla(OXA51/66) genes were detected by PCR. Strain typing for bla(OXA-58)-carrying Acinetobacter baumannii isolates was performed by Enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR), multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). RESULTS: A total of 115 Acinetobacter baumannii isolates were verified by recA gene and bla(OXA-51/6)6 detection. Among them, nine (7.8%) isolates carry bla(OXA-58) with reduced susceptibility to imipenem (MIC > or = 2 mg/L) were observed. ERIC-PCR fingerprints of nine bla(OXA-58)-carrying isolates were highly similar. MLST revealed that eight isolates were ST95 and one isolate was ST75. PFGE showed that eight isolates with the same sequence type were of the same fingerprint types, which were of two closely-related subtypes. CONCLUSION: In West China Hospital, some Acinetobacter baumannii isolates with reduced susceptibility to carbapenem carried bla(OXA-58). The major spread way of bla(OXA-58)-carrying isolates was clonal dissemination.

[Effects of bone morphogenetic protein-7 therapy on E3 ubiquitin ligase expression in mouse liver with experimentally induced fibrosis].

OBJECTIVE: This study explored the dynamic expression of the E3 ubiquitin-protein ligase gene, Arkadia, in response to carbon tetrachloride (CCl4)-induced liver fibrosis in a mouse model and investigated the differential expression that occurs following treatment with the anti-fibrotic bone morphogenetic protein-7 (BMP-7). METHODS: Thirty healthy male imprinting control region (ICR) mice were randomly assigned to three groups: normal (control; n = 6), CCl4-induced model group (model; n = 18), and CCl4-induced model with BMP-7 treatment group (treatment; n = 6). The model group was further divided into three subgroups (n = 6 each) for analysis at 4, 8 and 12 weeks after fibrosis induction. Liver fibrosis was induced by hypodermic injections of 60% CCl4 /peanut oil (5 mL/kg) to the hind legs of mice two-times per week in alternating legs for a period of 12 weeks. At week 9, the treatment group of CCl4-induced mice were given an intraperitoneal injection of BMP-7 (300 pg/g) simultaneously with that day's hypodermic injection of 60% CCl4 /peanut oil, and then every other day for a period of four weeks. The pathological changes in liver tissues were observed after staining with hematoxylin-eosin (HE) and Masson's trichrome. Messenger RNA (mRNA) and protein expression of Arkadia in liver were evaluated using reverse transcription-polymerase chain reaction and immunohistochemistry and Western blotting, respectively. RESULTS: Mouse models of liver fibrosis were successfully established by CCl4 exposure. Arkadia, Smad7 and TGF-beta1 mRNA levels were up-regulated in the model group in a time-dependent manner (vs. control group), and BMP-7 treatment led to significant down-regulation of the CCl4-induced expression of the three genes (vs. control group: F = 812.80, 451.46, and 998.96, respectively; P less than 0.01). At week 12, the mRNA levels of Arkadia, Smad7, and TGF-b1 were significantly lower in the BMP-7 treatment group than in the model group (t = 12.108, 18.737, and 16.364, respectively; P less than 0.01). Arkadia, Smad7, and TGF-b1 protein staining was weak in the portal area of control liver tissue. In contrast, the model group showed significantly stronger staining for all three proteins in the portal area and in the cytoplasm of liver cells. The staining of Arkadia, Smad7, and TGF-b1 proteins was significantly lower in the treatment group (vs. control group: F = 8.399, 609.690, and 900.561, respectively; P < 0.01). At week 12, the protein levels of Arkadia, Smad7, and TGF-b1 were significantly lower in the treatment group than in the model group (t = 23.438, 11.667, and 42.889, respectively; P < 0.01). CONCLUSION: Arkadia expression gradually increased along with the development of liver fibrosis but was suppressed by treatment with the anti-fibrotic factor, BMP-7.

[Dynamic expression of tropomyosin 1 in rat model of hepatic fibrosis and hepatic stellate cells].

OBJECTIVE: To investigate the dynamic expression of TPM1 in rat model of hepatic fibrosis and hepatic stellate cells induced by TGFß1. METHOD: Thirty male SD rats were divided into control group (n = 6) and model group (n = 24). The rat model of hepatic fibrosis was established by intraperitoneal injection of dimethylnitrosamine(DMN). The sera were collected from portal vein and liver tissues were taken from animals 2, 4, 6, 8 weeks HSC-T6 cells were cultured and induced 48 hours by 5 ng/ml TGF-ß1. The pathological changes of liver were observed by Hematoxylin-Eosin and Masson Staining. Reverse Transcription-polymerase chain reaction (RT-PCR), immunohistochemistry and Western-blotting were used to determine the mRNA and protein expressions of TPM1, TGFß1 and α-SMA in rat models and HSC-T6 cells and the localization of TPM1 in rat models. RESULTS: Rat models of hepatic fibrosis were successfully established. TPM1 was lowly stained in the wall of blood vessels in portal areas in normal livers, in fibrotic livers TPM1 was mainly stained along the fibrotic septum. The mRNA and protein expressions of TPM1 and α-SMA in rat models of hepatic fibrosis increased at the week 2 and peaked at week 6, which was statistical significance compared to control group, P < 0.05; TGF-ß1 increased at week 2 and it was higher than the levels in other groups at week 4, which was statistical significance compared to control group P < 0.05; Correlation analysis showed that TPM1 positively correlated with α-SMA and TGF-ß1, rs = 0.688, rs = 0.692, P < 0.01. In HSC-T6, the mRNA expressions of TPM1 and α-SMA increased after being induced by TGF -beta1. compare with control group, the differences were significant, P less than 0.05. CONCLUSION: TPM1 may be playing an important role in the occurrence and development of liver fibrosis. Maybe it could become a potential therapeutic target for hepatic fibrosis.

[Study of detection and homology analysis of the 16S rRNA methylase in 374 enterobacteriaceae clinical isolates].

OBJECTIVE: To investigate the prevalence of genes encoding 16S rRNA methylase and the spreading path of these genes in 374 clinical isolate of enterobacteriaceae. METHODS: The genes encoding 16S rRNA methylase in 374 clinical isolate of enterobacteriaceae was detected with PCR. The sequence homogeny analyses were carried out with the NCBL BLAST program and enterbacterial repetitive intergenic consensus PCR (ERIC-PCR). The conjugation experiments were used to determine the transference of 16S rRNA methylase in vitro. RESULTS: In 374 clinical isolates, methylase genes were detected in 24 strains (6.41%), including 10 armA gene positive strains and 10 rmtB gene positive strains, and 4 strains with both genes positive. Highly homogenous strains were confirmed by ERIC-PCR. 45.8% (11/24) of the conjunction experiments for these strains were positive. CONCLUSION: The aminoglycoside resistance in enterobacteriaceae was concerned related to 16S rRNA methylase. The 16S rRNA methylase transferred either by clone or by plasmids horizontal spreading.

[Diagnosis of infective endocarditis by Duke criteria and a new national criteria in a cohort of 205 patients].

OBJECTIVE: To compare the value of the new national criteria (2 major or one major plus 3 minor criteria) with the Duke criteria for diagnosis of infective endocarditis (IE). METHODS: A total of 205 patients with clinical diagnosis of IE admitted at West China Hospital of Sichuan University were included in this study. Among them, IE was pathologically confirmed in 97 patients. The sensitivities of both criteria for the diagnosis of IE were compared. RESULTS: In 205 cases, the same microorganisms were detected twice in blood cultures in 13 cases (8.3%). Vegetations were detected by echocardiography in 183 patients (89.3%). In 97 cases with pathologically confirmed IE, the same microorganisms were detected twice in blood cultures in 6 cases (6.2%). Vegetations were detected by echocardiography in 89 patients (91.8%). IE diagnose was made in 44 (45.5%) and 86 (88.7%, P < 0.05 vs. Duke criteria) out of 97 pathologically confirmed IE patients by the Duke criteria and new national criteria, respectively. The specificities were 100% and 95.7% by Duke and new national criteria, respectively (P > 0.05). CONCLUSION: With the addition of echocardiographic evidence of endocardial involvement and 2 minor criteria as definite diagnostic criteria, the sensitivity of the new national criteria is superior to that of the Duke criteria for diagnosing IE and the specificity for the diagnosis of IE between the two criteria is similar.

Electrosprayed Ultra-Thin Coating of Ethyl Cellulose on Drug Nanoparticles for Improved Sustained Release.

In nanopharmaceutics, polymeric coating is a popular strategy for modifying the drug release kinetics and, thus, new methods for implementing the nanocoating processes are highly desired. In the present study, a modified coaxial electrospraying process was developed to formulate an ultra-thin layer of ethyl cellulose (EC) on a medicated composite core consisting of tamoxifen citrate (TAM) and EC. A traditional single-fluid blending electrospraying and its monolithic EC-TAM nanoparticles (NPs) were exploited to compare. The modified coaxial processes were demonstrated to be more continuous and robust. The created NPs with EC coating had a higher quality than the monolithic ones in terms of the shape, surface smoothness, and the uniform size distribution, as verified by the SEM and TEM results. XRD patterns suggested that TAM presented in all the NPs in an amorphous state thanks to the fine compatibility between EC and TAM, as indicated by the attenuated total reflection (ATR)-FTIR spectra. In vitro dissolution tests demonstrated that the NPs with EC coating required a time period of 7.58 h, 12.79 h, and 28.74 h for an accumulative release of 30%, 50%, and 90% of the loaded drug, respectively. The protocols reported here open a new way for developing novel medicated nanoparticles with functional coating.

Clinical evaluation of oral levofloxacin 500 mg once-daily dosage for treatment of lower respiratory tract infections and urinary tract infections: a prospective multicenter study in China.

Levofloxacin (LVFX), a fluoroquinolone agent, has a broad spectrum that covers Gram-positive and -negative bacteria and atypical pathogens. It demonstrates good clinical efficacy in the treatment of various infections, including lower respiratory tract infections (LRTIs) and urinary tract infections (UTIs). To evaluate the efficacy and safety of oral LVFX 500 mg once daily, a large open-label clinical trial was conducted in 1266 patients (899 with LRTIs and 367 with UTIs) at 32 centers in China. In the per-protocol population, the clinical efficacy rate (cure or improvement) at 7 to 14 days after the end of treatment was 96.4% (666/691) for LRTIs and 95.7% (267/279) for UTIs. In 53 patients diagnosed with atypical pneumonia the treatment was effective. The bacteriological efficacy rate was 96.6% (256/265) for LRTIs and 93.3% (126/135) for UTIs. The eradication rate of the causative pathogens was 100% (33/33) for Haemophilus influenzae and 96.0% (24/25) for Streptococcus pneumoniae in LRTIs, and 94.1% (80/85) for Escherichia coli in UTIs. The overall efficacy rates were 89.3% (617/691) for LRTIs and 87.8% (245/279) for UTIs. The incidence of drug-related adverse events (ADRs) was 17.3% (215/1245), and the incidence of drug-related laboratory abnormalities was 15.7% (191/1213). Common ADRs were dizziness, nausea, and insomnia. Common laboratory abnormalities included "WBC decreased", "alanine aminotransferase (ALT) increased", "aspartate aminotransferase (AST) increased", and "lactate dehydrogenase (LDH) increased". All of these events were mentioned in the package inserts of fluoroquinolones including LVFX, and most events were mild and transient. Thirty-four patients (2.7%) were withdrawn from the study because of the ADRs. No new ADRs were found. This study concluded that the dosage regimen of LVFX 500 mg once daily was effective and tolerable for the treatment of LRTIs and UTIs.

The Process⁻Property⁻Performance Relationship of Medicated Nanoparticles Prepared by Modified Coaxial Electrospraying.

In pharmaceutical nanotechnology, the intentional manipulation of working processes to fabricate nanoproducts with suitable properties for achieving the desired functional performances is highly sought after. The following paper aims to detail how a modified coaxial electrospraying has been developed to create ibuprofen-loaded hydroxypropyl methylcellulose nanoparticles for improving the drug dissolution rate. During the working processes, a key parameter, i.e., the spreading angle of atomization region (θ, °), could provide a linkage among the working process, the property of generated nanoparticles and their functional performance. Compared with the applied voltage (V, kV; D = 2713 - 82V with RθV2 = 0.9623), θ could provide a better correlation with the diameter of resultant nanoparticles (D, nm; D = 1096 - 5θ with RDθ2 = 0.9905), suggesting a usefulness of accurately predicting the nanoparticle diameter. The drug released from the electrosprayed nanoparticles involved both erosion and diffusion mechanisms. A univariate quadratic equation between the time of releasing 95% of the loaded drug (t, min) and D (t = 38.7 + 0.097D - 4.838 × 105D2 with a R2 value of 0.9976) suggests that the nanoparticle diameter has a profound influence on the drug release performance. The clear process-property-performance relationship should be useful for optimizing the electrospraying process, and in turn for achieving the desired medicated nanoparticles.

[Study on the correlation between resistance phenotype and expression level of femA of Staphylococcus aureus].

OBJECTIVE: To detect the expression level of femA of Staphylococcus aureus strains with different phenotype. METHODS: 15 strains of the non-beta-lactamase-producing clinical isolates with different phenotype by agar dilution and by nitrocephin paper strip method were chosen as the object of test, in addition to 4 donative strains (BB270, BB308, BB586, COL). Total RNA were extracted and analysed by agarose gel electrophoresis. Real time fluorescent quantitative PCR was performed to quantify the expression of femA gene. The expression level of femA of BB270 was set to be standard(100%). RESULTS: The expressions of femA were observed in all the tested strains. The amount of femA-specific mRNA in the mutant strain BB308 was approximately 37.82% and that of stain BB586 was 240.50%, homogeneous resistant strain COL was 862.61%. The amounts in MSSA strains were from 0.00353% to 29.92%, that in low-level MRSA strains were from 0.00554% to 310%, otherwise that in high-level MRSA strains were from 13.88% to 55000%, which were different among these groups. There was no significant difference in amount of femA-mRNA between MSSA and low-level MRSA strains (P1 = 0.83) but marked between high-level MRSA and low-level MRSA/MSSA strains (P2 = 0.006, P3 = 0.01)). CONCLUSION: Expression level of femA in high-level MRSA was significant higher than that in low-level MRSA and MSSA. femA was essential for the expression of high-level methicillin resistance in MRSA.

[A multicentre study on the pathogenic agents in 665 adult patients with community-acquired pneumonia in cities of China].

OBJECTIVE: To investigate the pathogenic causes of community-acquired pneumonia (CAP) in adult patients in China, the relation of previous antibiotic use and the Pneumonia Patient Outcome Research Team (PORT) classification to microbial etiology, and the prevalence of drug resistance of common CAP bacteria. METHODS: A prospective study was performed on 665 consecutive adult patients with CAP at 12 centers in 7 Chinese cities during one year. The etiology of pneumonia was considered if one of the following criteria was met: (1) valid sputum sample yielding one or more predominant strains; (2) blood cultures yielding a bacterial pathogen; (3) seroconversion, a > or = 4-fold increase or decrease titers of antibodies to Mycoplasma pneumoniae, Chlamydia pneumoniae and Legionella pneumophila. Minimum inhibitory concentration (MIC) of respiratory tract isolates was determined using the agar dilution method. RESULTS: Pathogens were identified in 324/610 patients (53.1%) with valid serum samples and sputum cultures as follows: Mycoplasma pneumoniae (126, 20.7%), Streptococcus pneumoniae (63, 10.3%), Haemophilus influenzae (56, 9.2%), Chlamydia pneumoniae (40, 6.6%), Klebsiella pneumoniae (37, 6.1%), Legionella pneumophila (31, 5.1%), Staphylococcus aureus (23, 3.8%), Escherichia coli (10, 1.6%), Moraxella catarrhalis (8, 1.3%), Pseudomonas aeruginosa (6, 1.0%). Of 195 patients with a bacterial pathogen, an atypical pathogen was identified in 62 (10.2%) cases. The non-susceptibility rate of Streptococcus pneumoniae to penicillin, azithromycin, and moxifloxacin was 20.3%, 75.4% and 4.3% respectively. CONCLUSIONS: Atypical pathogens have important role in CAP, with Mycoplasma pneumoniae being the most common pathogen, and mixed infection of atypical pathogens with bacteria was found in 10.2% of the cases. Streptococcus pneumoniae and Haemophilus influenzae remain the most important bacteria for CAP. More than 75.0% of Streptococcus pneumoniae was resistant to macrolides and 20.3% was resistant to penicillin.

[Investigating the fluoroquinolone molecular resistant mechanism of Stenotrophomonas maltophilia].

OBJECTIVE: To research DNA gyrase and topoisomerase IV quinolone resistance-determining regions (QRDRs) in Stenotrophomonas maltophilia clinical isolates with different resistant levels of quinolone susceptibility. METHODS: We selected five strains for which the MIC of ciprofloxacin were higher than 2 mg/L and were negative for efflux mechanism; then we amplified their QRDRs of gyrA and parE, purified the fragment, and analyzed the nucleotide sequences. RESULTS: In Stenotrophomonas maltophilia DNA gyrA, the changes at positions 83 and 87 commonly involved in quinolones resistance in gram-negative bacteria were absent, and there was Gln but not Ser or Thr. Of the five strains, one strain showed a ParE amino acid change in position 402, the other was in position 432, but the mutations were not associated with FQNS resistance. CONCLUSION: FQNS resistance in Stenotrophomonas maltophilia is related to active efflux pump and may be correlated with a low level of permeability. But it is not clear whether the resistance is related to the mutants in DNA gyrase and topoisomerase N.

[A study on the mechanism of drug resistance in Staphylococcus aureus].

OBJECTIVE: To inquire into the mechanism of drug resistance in Staphylococcus aureus. METHODS: A total of 198 strains of Staphylococcus aureus were isolated from the samples sent to the Clinical Laboratory of Microbiology,West China Hospital. The resistance of Staphylococcus aureus to Methicillin was assayed with agar dilution. Staphylococcus aureus mecA gene was measured by PCR assay and beta-lactamase was detected by Nitrocephin. RESULTS: The rate of resistance to methicillin was 64.65% in 198 strains of Staphylococcus aureus; 118 strains of methicillin-resistant staphylococcus aureus(MRSA) were found to have high level resistance in 128 MRSA;10 strains of MRSA were found to have low level resistance; 41(58.57%) strains of methicillin-sensitive Staphylococcus aureus (MSSA) expressed beta-lactamase; 2 Staphylococcus aureus had mecA among them; 67 Staphylococcus aureus expressed beta-lactamase in high level resistance, 63(53.39%)Staphylococcus aureus expressed beta-lactamase in high level resistance, among them, 5 Staphylococcus aureus had mecA; 40.00% MRSA expressed beta-lactamase in low level resistance, 55 MRSA did not express beta-lactamase in high level resistance, which had all mecA; 9 Staphylococcus aureus did not express beta-lactamase in low level resistance, among them, 5 Staphylococcus aureus had mecA. The difference in expression of beta-lactamase was statistically significant between MSSA and MRSA; MRSA(53.39%) was lower than MSSA (58.57%); the other differences were not significant. The difference in having mecA was statistically significant between MRSA(having high resistant level and no expression of beta-lactamase) and the others; MRSA had higher mecA than did the others. CONCLUSION: The resistance in Staphylococcus aureus mainly involved two mechanisms: the expression of beta-lactamase and the expression of mecA.

[The adverse reactions of parenteral norvancomycin in 1031 patients].

OBJECTIVE: To investigate the safety of norvancomycin, and provide basis for its rational use in clinical practice. METHODS: We documented all adverse events occurred in inpatients who receive intravenous infusion of norvancomycin, then we evaluated the relationship between adverse events and norvancomycin and calculated the rates of adverse reaction. RESULTS: 1031 patients were enrolled in this study from March 2002 to June 2003 and 965 of them could be evaluated. 80 adverse reactions occurred in 965 patients who received norvancomycin, giving a total adverse reaction rate of 8.29%. The systemic adverse reactions included renal impairment (4.04%), hepatic impairment (2.38%) and allergic reaction (1.76%). 15 patients discontinued the treatment because of the adverse reaction. The rates were higher in patients who use other antimicrobial agents concomitantly or whose age >/= 60 years. The rates of renal impairment were higher in those with age >/= 60 years, and the rates of hepatic impairment were higher in whose received this agent longer than 14 days. These factors were independent risk factors (P < 0.05). CONCLUSIONS: The overall adverse reaction rate of norvancomycin was low. A few patients experienced drug-related reaction, most of these adverse reactions were mild and tolerable. The adverse reactions tended to occur in older patients, those who use other antibiotic concomitantly or those who receive this agent longer than 14 days.