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ABSTRACT: This study analyzed the relationship between the ISEcp1 element and bla(CTX-M) genes of Escherichia coli isolates that produce extended-spectrum β-lactamase (ESBL) in community settings.
Nineteen E. coli isolates that produced CTX-M-type β-lactamase were collected from four communities of elderly people in Shenyang, China. Polymerase chain reaction (PCR) amplification and direct sequencing were used to detect the insertion of the ISEcp1 element into the genetic environment of the bla(CTX-M) genes.
The ISEcp1 element was associated with several bla(CTX-M) gene types, including CTX-M-14, CTX-M-24, CTX-M-22, and CTX-M-79. Sequence analysis revealed that all of the ISEcp1-like DNA sequences contained the putative promoter region that is involved in CTX-M genes transcription. ISEcp1 insertion sequences were observed 42-127bp upstream of the open reading frames (ORFs) that encode the CTX-M enzymes in all 15 strains. The CTX-M-79 β-lactamase-encoding gene was observed with a different ISEcp1 insertion site and variable sequences between the ISEcp1 and bla(CTX-M-79) gene. For one strain (T298), the ISEcp1 element was disrupted by IS10.
This work confirmed that the ISEcp1 elements were closely linked to bla(CTX-M) genes in community isolates from Shenyang, China.
Enfermedades Infecciosas y Microbiología Clínica 12/2011; 29(10):731-4. · 1.49 Impact Factor
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ABSTRACT: The investigation was carried out to elucidate the molecular characteristics and resistant mechanisms of imipenem-resistant Acinetobacter baumannii. Thirty-seven isolates were collected from January 2007 to December 2007. The homology of the isolates was analyzed by both pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). The genes of β-lactamases, adeB, and class 1 integron were polymerase chain reaction amplified. Genotype analysis of the 37 A. baumannii isolates by PFGE revealed the circulation of four PFGE types (A-D); the A- and B-type accounted for 48.6% and 40.5%, respectively. MLST showed the existence of three allelic profiles. The agar dilution method was carried out to determine the MIC of imipenem, in the absence or presence of carbonyl cyanide m-chlorophenylhydrazone (CCCP, 10 μg/ml). The MICs of the strains to imipenem were between 16 μg/ml and 128 μg/ml. When CCCP was added, a MIC decrease of at least four-fold was observed in 20 isolates, which belonged to the A- or C-type. AdeB and bla (PER-1) genes were each detected in 35 isolates, bla (OXA-23) gene in 34 isolates and bla (OXA-58)-like gene in 24 isolates. All isolates harbored bla (OXA-51)-like genes. No isolates carried the bla (IMP-1) gene. Integron was detected in 25 isolates, which mediated the resistance to aminoglycosides and rifampin. The epidemiologic data suggested that the increasing infection of A. baumannii in our hospital was mainly caused by the inter-hospital spread of two epidemic clones. The AdeABC efflux system may be the important factor that leads to the high level of imipenem-resistance in PFGE A-type.
The Journal of Microbiology 10/2010; 48(5):689-94. · 1.10 Impact Factor
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ABSTRACT: To determine the possible genetic background and the source of our hospital's 43 clinical isolates of multidrug-resistant Acinetobacter baumannii, and the category of gene cassettes in type 1 integrons of all strains.
Restriction enzyme Apa I was chosen for all strains in pulsed-field gel electrophoresis (PFGE) methods. Multilocus sequence typing (MLST) was used to compare the allelic profiles of all the strains. PCR method was used for amplify the integrons of all strains.
PFGE results showed that 43 strains were divided into four types. A-type and B-type were divided into 4 and 2 subtypes, respectively. The MLST results showed the existing of three allelic profiles: 1-3-3-2-2-7-3, 1-3-3-2-2-11-3, and 1-3-3-2-2-14-3. B-type and D-type of PFGE have the same allelic profile (1-3-3-2-2-11-3). A-type strains were detected mainly in ICU, and in burn unit only found B- and D-type. The same integron was detected in 62.8% of the strains. The constituent ratio of A1, A2, A3, A4, B1, B2, C and D-type was 40.7%, 18.5%, 7.4%, 3.7%, 14.8%, 3.7%, 3.7% and 7.4%, respectively.
The coexistence of multiple cloning system in this region was proved by the PFGE and MLST, and the same clone can evolve to different subtypes when stimulated by different environmental conditions; and the different carrying-situation of the same integron in strains prove the possibility of the change during the evolution of resistance mechanisms.
Zhonghua nei ke za zhi [Chinese journal of internal medicine] 08/2010; 49(8):657-61.
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ABSTRACT: To examine common antimicrobial regimens used in eradicating certain nosocomial gram-negative pathogens and determine which ones are likely to be the most suitable as empirical choices in Shenyang, China.
A 5000-subject Monte Carlo simulation was conducted to determine the cumulative fraction of response (CFR) for meropenem, imipenem, cefepime, piperacillin/tazobactam and levofloxacin against Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Acinetobacter baumannii and Pseudomonas aeruginosa collected in 2006 and 2007 from Shenyang.
Meropenem and imipenem had the highest CFRs against the Enterobacteriaceae (97%-100%), followed by cefepime. No antibiotic simulated regimen achieved optimal CFR against P. aeruginosa and A. baumannii. Piperacillin/tazobactam dosed at 4.5 g q8h achieved the lowest CFR against all bacteria.
This study suggests that the carbapenems provide the greatest likelihood of clinical success for the Enterobacteriaceae, and combination therapy might be needed when choosing empirical therapy, especially when A. baumannii or P. aeruginosa are suspected.
BMC Infectious Diseases 01/2010; 10:171. · 3.12 Impact Factor
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ABSTRACT: The importance of community-acquired infections due to extended-spectrum beta-lactamase-producing (ESBL) Escherichia coli has been increasingly recognized in recent years. No comprehensive data are available on the prevalence, risk factors, and genotypes of ESBL production in community residents in China. Rectal samples from 270 elderly people were collected in four communities in Shenyang (China). Colonies were screened by double-disk synergy test for ESBL production and then, ESBLs were characterized by PCR and sequencing. The clonal relatedness of all ESBL-producing isolates was determined by pulsed-field gel electrophoresis. Potential risk factors for rectal carriage of ESBL producers were examined by multivariate analysis. The prevalence of rectal carriage of ESBL-producing E. coli was 7.0%. All 19 ESBL-producing isolates produced CTX-M-type ESBLs, including CTX-M-14 (11 strains), CTX-M-22 (3 strains), CTX-M-79 (3 strains), CTX-M-24 (1 strain), and CTX-M-24 and CTX-M-79 together (1 strain). CTX-M-79 ESBL was first detected worldwide. ESBL-producing strains were clonally unrelated. Appearance of ESBL producers is strongly associated with the use of antibiotics in the past 3 months (odds ratio 3.2, 95% CI 1.1-9.0, P = 0.03). Our results show the importance of the intestinal tract as a reservoir for ESBL-producing isolates in community settings in China and that the use of antibiotics in the past 3 months is clearly linked to rectal carriage of ESBL producers.
Canadian Journal of Microbiology 10/2008; 54(9):781-5. · 1.36 Impact Factor
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ABSTRACT: To investigate the alternations in gene/amino acid sequence of penicillin-binding protein (PBP)2b from clinical isolates of penicillin-nonsusceptible Streptococcus pneumonia (PNSP) in this region.
24 strains of Streptococcus pneumonia were collected from January to December 2006. The antibiotics susceptibility of these strains was detected. PCR amplification and direct sequencing of pbp2b genes were performed. The sequence variations of PBP genes of the PNSP in this region were studied with sequence BLAST analysis.
Three prominent substitutions were common to 13 PNSP isolates with minimal inhibitory concentration (MIC) at least 0.1 mg/L. These included the replacement of Thr(445)--> Ala following the conservative motif SSN, Glu(475)-->Gly and Thr(488)-->Ala/Ser. The exchange of Glu(332)-->Gly was identified in 12 PNSP isolates of which the MIC was at least 0. 25 mg/L. Seven penicillin resistant Streptococcus pneumonia (PRSP) isolates (MIC > or = 3 mg/L) shared the amino acid substitution Ala(618)-->Gly adjacent to third conserved (KTG) motif and the PBP2b sequences of seven PRSP isolates were classified within Baek's group II and were very similar to those of the Korean J77 isolate. Novel gene and amino acid sequence variants in isolate 14, 15, 8, 11 and 24 was identified in this study and these gene sequences have been deposited in the GenBank database and assigned accession no. EU035970, EU056919, EU056920, EU056921 and EU106886.
Analysis of pbp2b genes revealed highly similar patterns of nucleotide and amino acid sequence variation among most resistant isolates, while penicillin intermediate Streptococcus pneumonia might be associated with novel gene sequence variants.
Zhonghua nei ke za zhi [Chinese journal of internal medicine] 07/2008; 47(6):491-4.
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ABSTRACT: To investigate the expression of nuclear factor-kappa B (NF-kappaB) and cytokines in Pseudomonas aeruginosa (PA)-induced pneumonia of rats, and the effect of pyrrolidine dithiocarbamate (PDTC).
Seventy-two male SD rats were divided into three groups at random:a control group, a PA group and a PDTC group (n = 24 each). The PA induced pneumonia model was established in SD rats. The rats of the control group and the PA group were intraperitoneally given saline (1 ml) at 60 min before PA exposure, while the rats of the PDTC group received the same volume of PDTC (200 mg/kg). After 60 min, the rats of the PA group and the PDTC group were intratracheally instilled with PA 0.2 ml (6 x 10(8) CFU/ml), while the rats of the control group received the same volume of saline. At 3 h, 6 h, 16 h, 24 h after PA exposure, the rats were examined. Then they were sacrificed and the lung were excised for routine histological analysis. Immunohistochemical staining with an antibody against activated NF-kappaB and Western blot were performed to detect the expression of NF-kappaB. The change of TNFalpha mRNA was identified by reverse transcriptase polymerase chain reaction (RT-PCR).
Histological findings demonstrated that the lung exposed to PA showed significant changes in the lung structure, edema and pronounced inflammatory cell infiltration. Both symptoms and damages of the lung were less severe in the rats of PDTC group than those of the PA group. Compared with the PDTC group, the activation of NF-kappaB and the expression of TNFalpha in the PA group were significantly upregulated after PA challenge 3 - 24 h (P < 0.01), respectively; peak expression of NF-kappaB and TNFalpha were observed at 3 - 6 h after PA exposure.
The expression of NF-kappaB and TNFalpha induced by NF-kappaB play an important role in the pathogenesis of pneumonia. The inhibitor of NF-kappaB, PDTC, can relieve the lung damages produced by pneumonia.
Zhonghua nei ke za zhi [Chinese journal of internal medicine] 11/2007; 46(10):815-9.
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ABSTRACT: To investigate the role of replacement of third-generation cephalosporins by piperacillin-tazobactam (pip-tazo) in influencing the colonization of extended-spectrum beta-lactamases (ESBLs)-producing Escherichia coli (E. coli) in intestinal tract.
The study was divided into two phases lasting altogether 9 months, namely the pre-replacement phase (phase I, 3 months) and replacement phase (phase II, 6 months). In the latter phase, third-generation cephalosporins was restricted and replaced by pip-tazo. In phase I and phase IIb (the last 3 months of phase II), clinical data and rectal swab were taken for E. coli isolation as follow: within 24 hrs after admission (baseline screening), every week and 48 hrs before discharge. ESBLs production was detected with double disc test. Acquisition rate of ESBLs-producing E. coli were calculated both in ES1 group (patients' rectal swab collected and tests at least 2 times) and ES2 group (ES1 but with negative ESBLs either at the time of screening on admission or at anytime during the hospital stay). Continuous variable was compared using unpaired t-test and categorical variables was compared using Pearson Chi square test. Fisher's exact test was used in the two phases.
In phase IIb, as compared with in phase I, the total consumption of antibiotics other than pip-tazo was reduced by 38.40%, the third-generation cephalosporins consumption was reduced by 70.11%, but pip-tazo consumption was raised by 895.35%. Meanwhile, the acquisition rate of ESBLs-producing E. coli in rectal swab was significantly decreased in phase IIb as compared with phase I (11.4% vs 24.0%) in ES1 group and the same is true in ES2 group (11.8% vs 27.9%).
Replacement of third-generation cephalosporin with pip-tazo can reduce colonization of ESBLs--producing E. coli in intestinal tract.
Zhonghua nei ke za zhi [Chinese journal of internal medicine] 10/2007; 46(9):714-7.
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ABSTRACT: It is recognized that lung fibroblasts (LF) act as a common pathway in the development of fibrosis from alveolitis of whatever etiology. The study was undertaken to identify the modulating effects of insulin-like growth factor-1 (IGF-1) on LF glucose metabolism and functions, to explore possible therapeutic targets through modulating LF for the treatment of pulmonary fibrosis.
Human embryonic lung (HEL) diploid fibroblast cells were cultured for 24 h with blank control, 100 ng/ml IGF-1, 200 ng/ml IGF-1, 100 ng/ml IGF-1 + 100 ng/ml insulin, 100 ng/ml IGF-1 + 200 ng/ml insulin, 100ng/ml insulin, 200 ng/ml insulin, respectively. The culture supernatants and cell pellets were collected to extract proteins and mRNAs. After quantitated with ultraviolet spectrometer, RT-PCR and Northern blotting were performed to determine the content of glucose transporter-4 (Glut-4), hexokinase II, elastin and collagen-IV.
RT-PCR showed that the general mean absorbance ratios of Glut-4 and HK-IImRNA in IGF-1 group were (0.67 +/- 0.25) and (0.60 +/- 0.19), significantly increased as compared with that of control group [(0.61 +/- 0.12), (0.55 +/- 0.19)]; but decreased as compared with that of insulin group [(0.74 +/- 0.26), (0.71 +/- 0.23)]. The expression of elastin, collagen protein in IGF-1 group [(174.3 +/- 4.2), (142.1 +/- 1.0)] were significantly stronger than that of insulin group.
IGF-1 can stimulate LF glucose metabolism, companied with increased expression of elastin and collagen IV in a concentration-dependent manner. IGF-1 can decrease the effect of insulin on LF glucose metabolism, whereas insulin can attenuate the effect of IGF-1 on LF in elastin and collagen expression.
Zhonghua jie he he hu xi za zhi = Zhonghua jiehe he huxi zazhi = Chinese journal of tuberculosis and respiratory diseases 09/2007; 30(8):605-9.
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ABSTRACT: To investigate whether the effect of E. coli on U937 cell lines apoptosis is mediated via p38 mitogen-activated protein kinase (MAPK) activation.
The U937 cell lines were treated with E. coli at different time or together with SB203580, an inhibitor for p38. Cell apoptosis was analyzed by flow cytometry. p38 activities were detected by Western blotting.
E. coli induced apoptosis in cultured U937 cell lines in a time-dependent manner. The phosphorylation of p38 was induced after 10 minutes infection, reached the peak after 20 minutes, and started to decline after 30 minutes. In contrast, the level of total p38 protein was not changed in whole experimental period. Inhibition of p38 with SB203580 significantly inhibited E. coli induced apoptosis in U937 cells.
The activation of the p38 MAPK in U937 cell lines by E. coli is a major pathway to mediate the apoptosis.
Chinese Medical Sciences Journal 04/2007; 22(1):49-53.
