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Objective To investigate the effect of azithromycin,erythromycin and roxithromyein at varying concentration on the β-lactamase produced in the biofilm of Klebsiella pneumoniae.Methods Models of Klebsiella pneumoniae were built up with the modified flat-board method and identified with the confocal scanning laser microscopy.Thirty Klebsiella pneumoniae were incubated at 37 ℃for 24 h,and allocated into 7 groups:biofilm (group A),by 1 MIC azithromycin (group B1),by 1/8 MIC azithromycin (group B2),by 1 MIC erythromycin (group C1),by 1/8 MIC erythromycin (group C2),by 1 MIC roxithromycin (group D1),and biofilm induced by 1/8 MIC roxithromycin (group D2),with 200 μ1 each.The β-lactamase activity in each group was quantitated.Results The β-lactamase activity in group A,group B1,group B2,group C1,group C2,group D1 and group D2 was 0.6534,0.3196,0.4260,0.5028,0.5108,0.6524 and 0.6470 U/mg respectively.The β-lactamase activity in group B1,group B2,group C1 and group C2 was lower than that in group A,and statistically significant difference was observed (P＜0.05).The B-lactamase activity in group D1 and group D2 was similar to that in group A,and no statistically significant differences was observed between them (P＞0.05).The β-lactamase activity in group B1 was lower than that in group B2,and statistically significant difference was observed (P <0.05).No statistically significant difference was observed between group C1 and group C2 (P＞0.05).Conclusion Azithromycin at higher concentration exerts better effects on biofilm formation than other macrolides.
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Objective To observe the CT features of mycoplasma pneumoniae pneumonia. Methods CT features of 40 adult patients with serologically proven mycoplasma pneumoniae pneumonia were retrospectively reviewed. Results The most common CT findings of mycoplasma pneumoniae pneumonia were ground-glass opacity (34/40, 85.00%) and consolidation (28/40, 70.00%). The other findings included nodules (18/40, 45.00%), thickening of the bronchovascular bundles (6/40, 15.00%), interlobular septal thickening (6/40, 15.00%), mediastinal lymphadenopathy (6/40, 15.00%) and pleural effusion (4/40, 10.00%). Most of the ground-glass opacity and consolidation showed tendency of lobular distribution and involving the lower lobes. In some patients, the absorption of the lesions was slower than the relief of symptoms. Conclusion CT findings of mycoplasma pneumoniae pneumonia have some features, and can provide help for the diagnosis of mycoplasma pneumoniae pneumonia.
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Objective To investigate the influence of influenza virus A（H1N1,A/PR/8/34 strain）on alveolar fluid clearance（AFC）in vivo and the effects of β1-adrenergic agonist on AFC in rat lungs infected by H1N1.Methods Fortyfive rats were divided into control group（n =12）,H1N1 infection group（the rats were infected with influenza virus strain A/PR/8/34,n =18）,β1-adrenergic agonist groups（the rats were administrated with β1-adrenergic agonist after HIN1 infection,n =15）.AFC was estimated by the progressive increase in the albumin concentration over 30 minutes.The activity of cAMP and cGMP in the lung tissues of control,H1N1 infection and β1-adrenergic agonist groups was measured.Results The infection with H1N1 resulted in a decline in AFC 9.15±1.01% vs control group 17.25±1.01% and increased lung water content（W/D was 6.77±0.13 vs control group 4.99±0.02）.H1N1-mediated inhibition of AFC could be reversed to 14.41±1.41% by the administration of β1-adrenergic agonist denopamine.H1N1 infection increased cGMP levels 7.34±0.40 pmol·mg-1· mg-1 vs control group 5.10±1.88 pmol·mg-1·mg-1 and decreased cAMP levels 1.43±0.06 nmol·mg-1·mg-1 in lung tissues compared with control group.β1-agonist denopamine reversed the level of cAMP to 2.06±0.16 nmol·mg-1·mg-1 and cGMP to 6.16±1.36 pmol·mg-1·mg-1.Conclusion H1N1 infection decreased AFC and increased lung edema.β1-agonist denopamine could reverse AFC and the ratio of cAMP/cGMP in H1N1 infected lung tissues.β1-agonist might regulate AFC through the pathway of cAMP-PKA.
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OBJECTIVE To evaluate the mechanism that bacteria growing in biofilm(BF) always resist to antimicrobial agents,and to provide the theoretical basis for selecting antimicrobial agents in clinic. METHODS Model of Klebsiella pneumoniae and Escherichia coli bacterial biofilm was built up with the modified flat-board method and identified with the AgNO_3 staining and confocal scanning laser microscopy.We used imipenem to induce the ESBLs production of BF bacteria.ESBLs production was performed by the standard disk diffusion method. RESULTS The isolation rate of ESBLs producing strains in Klebsiella and E.coli planktonically was 20.0% and 22.5%,respectively.The isolation rate of ESBLs producing strains in Klebsiella biofilm and E.coli was 42.5% and 47.5%,respectively.The isolation rate of ESBLs producing strains in above two biofilms and(E.coli) biofilm being induced by imipenem was 65.0% and 70.0%,respectively.The isolation rate of groups A_1 and B_1,groups B_1 and C_1,groups A_2 and B_2,groups B_2 and C_2 was different from each other significantly with the statistic method of ?~2 test. CONCLUSIONS One of the main reasons that Klebsiella and E.coli resist to antibiotics is the synergetic effect of BF and ESBLs.
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Objective To investigate the reliability of appraising biofilm of Klebsiella with silver staining method.Methods Apply improved flat culture to make biofilm of Klebsiella,adopting silver staining method and scanning electron microscopy to observe and appraise.Results Observation with general optical microscope after silver staining to appraise biofolm is identical with that using scanning electron microscope.Conclusions Silver staining method used to appraise biofilm of Klebsiella is reliable and simple.
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AIM:To study the effect of ?1-adrenergic agonist on alveolar fluid clearance in hypoxic rat lungs. METHODS: Rats were exposed to 10% oxygen. Alveolar fluid clearance (AFC) and lung water content (TLW) were calculated in rats exposed to hypoxia for 24 h and 48 h. Isotonic 5% albumin in solutions with different pharmacological agents were instilled into the distal airways in the hypoxia exposed and room air-exposed rat lungs, and the AFC was examined. RESULTS: As compared with the room air-exposed rats (17.50%?2.66%), AFC in the rats exposed to 10% oxygen was not decreased (18.70%?3.19%), AFC in the rats exposed to 10% oxygen for 48 h was decreased (8.59%?2.60%). Denopamine, a ?1-adrenergic agonist, increased AFC significantly in the rats exposed to room air and hypoxia. The potency of 10-5 mol/L denopamine was similar to that of 10-5mol/L terbutaline. The denopamine effect was partly blocked by inhibitors of sodium transport amiloride and ouabain (AFC were 11.80%?2.79% and 8.53%?2.17%). CONCLUSION: Denopamine, a selective ?1-adrenergic agonist, stimulates alveolar fluid clearance in rats exposed to hypoxia through the active sodium transport, and may have therapeutical effect on pulmonary edema after acute lung injury.