ObjectiveTo analyze the pathogenic bacteria distribution, structure and characteristics of drug resistance in patients with acute stroke complicated with pulmonary infection, in order to provide reference for the prevention of hospital infection and rational use of antimicrobial agents. MethodsA total of 864 clinical specimens of acute stroke complicated with pulmonary infection were chosen for study between January 2012 and December 2014. Separation and cultivation were done in accordance with the operation procedures regulated by the Ministry of Health. Drug sensitivity examination was done by Kirby-Bauer (k-b). Super-extensive spectrum β lactamase (ESBL) and methicillin resistant staphylococcus aureus (MRSA) were detected to analyze the bacterial species and resistance transition. ResultsA total of 864 samples were cultivated, in which G-bacteria accounted for 61.2%. The main pathogenic bacteria was Klebsiella pneumoniae bacteria, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumanmii and Staphylococcus aureus. Imipenem had high antimicrobial activity to G-bacilli, especially to Escherichia coli and Klebsiella pneumoniae bacteria. Linezolid, vancomycin and teicoplanin had high antibacterial activity to staphylococcus aureus. Vancomycin resistant Staphylococcus aureus was not found. Ciprofloxacin had high antibacterial activity to Pseudomonas aeruginosa, while imipenem had low antibacterial activity to Pseudomonas aeruginosa. Amikacin had high antibacterial activity to acinetobacter. ConclusionG-bacilli are predominant in acute stroke complicated with pulmonary infection. ESBLs and MRSA detection rate is high, and we should pay attention to the rational use of antibiotics to reduce drug resistance.
Objective To observe and evaluate the efficacy of continuous drainage with intravenous catheter in the treatment of breast abscess infected by methicillin resistant staphylococcus aureus (MRSA) and to explore the best treatment methods. Methods Sixty cases of breast abscess infected by MRSA were retrospectively analyzed. The patients were divided into continuous drainage group and puncture drainage group according to the treatment. Continuous drainage with 14G intravenous catheter and intermittent aspiration with 20 mL syringe were performed to treat the breast abscesses in the continuous drainage group (n=36) and puncture drainage group (n=24), respectively. Meanwhile, sensitive antibiotics were used according to the results of susceptibility test. The therapeutic effects of the 2 groups were compared. Results There were no significant differences in baseline data between continuous drainage group and puncture drainage group (P>0.05). There was no significant differences of cure rate between the two groups (P=0.717). Compared with the puncture drainage group, the continuous drainage group showed shorter period of time to heal the breast abscess (P=0.001), shorter period of time to control the ache (P=0.038), less punctures (P<0.001) and more daily volume of drainage (P<0.001). No significant differences were found in the period of time to control the fever between the two groups (P=0.127). Conclusions Continuous drainage with intravenous catheter can shorten the course of disease, reduce the suffering of patients, reduce the difficulty of hospital infection prevention and control. It’s an ideal choice for the treatment of breast abscess infected by MRSA.
Objective To investigate the incidence rate, molecular epidemiology and risk factors for methicillin-resistant Staphylococcus aureus (MRSA) infection. Methods A total of 119 Staphylococcus aureus strains isolated from January 2016 to December 2020 in general surgery of this hospital were collected retrospectively and divided into MRSA group and methicillin-sensitive Staphylococcus aureus group according to whether or not resistant to oxacillin. The clinical data of all patients infected with Staphylococcus aureus and drug sensitivity of Staphylococcus aureus were collected. Molecular typing was performed by multilocus sequence typing (MLST), resistance gene, virulence gene and biofilm gene were detected by polymerase chain reaction (PCR) method, and a case-control study was used to identify risk factors for MRSA infection. ResultsThe detection rate of MRSA was 57.98% (69/119), mainly was from pus specimens (80.67%, 96/119). The results of MLST showed that the dominant clone types were ST88 (37.68%, 26/69), ST951 (27.54%, 19/69) and ST59 (18.84%, 13/69). The results of PCR showed that the detection rates of mecA, mecC, Aac (6′ )/Aph (2′ ′ ), Aph (3)-Ⅲ, ant (4′ )- Ⅰ a, tetM, qnrA, panton-valentine leukocidin, fibronectin-binding protein A, staphylococcal enterotoxin A, staphylococcal enterotoxin B, α-hemolysins, intracellular adhesion A, staphylococcal accessory regulators A, and fibronectin-binding protein B in 69 strains of MRSA were 100%, 0.00%, 27.54%, 34.78%, 18.84%, 14.49%, 1.45%, 8.70%, 98.55%, 11.59%, 91.30%, 94.20%, 92.75%, 97.10% and 86.96%, respectively. Multivariate analysis showed that hospital transfer, wound infection, catheter related infection, drainage tube and history of cephalosporin using were risk factors for MRSA infection. ConclusionsThe detection rate of MRSA in general surgery of this hospital is high. ST88 is the most common clone type. The carrying rates of resistant-, virulence- and biofilm-related genes are high. Hospital transfer, wound infection, drainage tube, history of cephalosporin using etc. are high risk factors for MRSA infection. It is advised that invasive operation should be reduced, antibiotics should be used rationally, hand hygiene should be paid attention to, environmental sanitation disinfection should be carried out regularly, and the monitoring of MRSA bacteria should be strengthened, so as to reduce and control the infection and spread of MRSA.
Objective To observe the inhibitory characteristics of silver nanoparticles (AgNP) on bacterial biofilms and investigate their inhibitory effect on biofilm formation on three common orthopedic biomaterials. Methods The minimal inhibitory concentration (MIC) and minimal biofilm inhibitory concentration (MBIC) of AgNP were determined by microplate dilution assay. Biofilms of Staphylococcus aureus (ATCC 25923) were cultured on three orthopedic biomaterials (titanium alloy, titanium oxide, and stainless steel) and intervened with AgNP at concentrations of 32, 16, 8, 4, 2 and 0 μg/mL to determine the MBICs on the three materials. The effects of AgNP on biofilm formation were analyzed by scanning electron microscopy and measuring optical density. Results The MIC and MBIC of AgNP in the microplate assay were both 16 µg/mL. The MBICs of AgNP on biofilm formation in titanium oxide, titanium alloy, and stainless steel were 16 μg/mL, 32 μg/mL, and 32 μg/mL, respectively. Among the three materials, the lowest optical density was observed on titanium oxide, while the highest was on titanium alloy. Conclusions AgNP has strong antibacterial biofilm characteristics and can prevent the formation of Staphylococcus aureus biofilm in vitro. Biofilm formation is most pronounced on titanium alloy, least on titanium oxide, and intermediate on stainless steel.
Objective To investigate the effect ofstaphylococcal lipoteichoic acid (LTA-sa) on RAW264.7 cells differentiation into osteoclasts. Methods RAW264.7 cells were cultured with LTA-sa of 100 ng/mL (group A), LTA-sa of 200 ng/mL (group B), LTA-sa of 400 ng/mL (group C), receptor activator of nuclear factor κB (NF-κB) ligand (RANKL) of 100 ng/mL as positive control (group D), and equal volume of PBS as blank control (group E) respectively for 5 days. And then, tartrate resistant acid phosphatase staining (TRAP) was used to detect the formation of osteoclast-like cells, Image-Pro Plus 6.0 software to measure the areas of bone resorption pits in Corning Osteo Assay Surface (COAS) wells, and MTT assay to observe the proliferation activity of RAW264.7 cells in group A, B, C, and E. Results After cultured for 5 days, the formation of osteoclast-like cells and bone resorption pits were observed in all groups. The number of osteoclast-like cells and the area of bone resorption pits in groups A, B, C, and D were more than those in group E. And with the increased concentration of LTA-sa, the indexes in groups A, B, and C increased gradually, but were lower than those in group D, and differences were significant between groups (P<0.05). At 5 days after culture, there was no significant difference in absorbance value among the experimental groups (groups A, B, C, and E) (P>0.05). Conclusion LTA-sa has promoting effect on RAW264.7 cells differentiation into osteoclasts.
ObjectiveTo investigate the molecular mechanism of osteoclast differentiation induced by Staphylococcal peptidoglycan (PGN-sa). MethodsRaw264.7 cells were stimulated with PGN-sa and with PGN-sa+SC75741[a potent inhibitor of nuclear factor κB (NF-κB) activation] in a concentration of 200 ng/mL. The protein expression of nuclear factor of activated T-cells cytoplasmic 1 (NFATc1) was tested at 0, 1, 2, and 3 days; the proteins related to osteoclast differentiation of extracellular regulated protein kinases (ERK), p38, c-Jun N-terminal kinase (JNK), NF-κB, inhibitor of NF-κB (IκB-α), Akt, and the phosphorylation forms of p38, ERK, JNK, Akt, NF-κB were measured at 0, 5, 10, 20, 40, and 60 minutes by Western blot. In addition, Raw264.7 cells were stimulated with PGN-sa in the concentrations of 100 ng/mL (group A), 200 ng/mL (group B), 400 ng/mL (group C), and with PBS (group D) for 1, 2, and 3 days; the expression levels of tumor necrosis factor α (TNF-α), interleukin 1α (IL-1α), and IL-6 were detected by ELISA. ResultsThe results of Western blot showed that the expression of NFATc1 increased gradually with time, showing significant difference between different time points (P<0.05). However, after SC75741 was added, the expression of NFATc1 was inhibited at 2 and 3 days, showing significant difference when compared with no addition of SC75741 (P<0.001). After stimulation of PGN-sa, the expression of IkB-α decreased significantly at 5 and 10 minutes when compared with those at the other time points (P<0.001), and returned to normal at 20 minutes. Meanwhile, the expression of p-NF-κB increased significantly at 5 and 10 minutes when compared with those at the other time points (P<0.001), and returned to normal at 20 minutes; and the expression of p-NF-κB at 5 minutes was significantly higher than that at 10 minutes (P<0.001). After the addition of SC75741, there was no change in the expressions of IκB-α and p-NF-κB, showing no significant difference between different time points P>0.05). Moreover, the expressions of ERK, p38, JNK, NF-κB, Akt, p-p38, p-ERK, p-JNK, and p-Akt showed no significant change between different time points P>0.05). ELISA results showed that there were no expressions of TNF-α and IL-1α in groups A-D at different time points. The expression of IL-6 had an increasing trend with time prolonged in each group, showing significant differences between different time points (P<0.05). Moreover, at 1 day after culture, the expression of IL-6 showed no significant difference among groups P>0.05). At 2 and 3 days after culture, the expression of IL-6 in groups A-C showed an increasing trend and was significantly higher than that in group D, showing significant difference among groups (P<0.05). ConclusionPGN-sa can promote osteoclast differentiation through NF-κB signaling pathway, and IL-6 may play a role in this process.
Objective To investigate the effect of aureolysin （Aur） on staphylococcus aureus biofilm formation of dacron biomaterial surfaces under different Aur concentration. Methods Ninety dacron biomaterials were divided into 3 groups （group A, group IA, control group） with random number table （30 piece in each group）. Dacron biomaterials were put into vials contained staphylococcus aureus （105 CFU/ml） respectively; then Aur was added to make the concentration at 400ng/ml in group A, and group B at 80ng/ml. The thickness and number of staphylococcus aureus biofilm on the surfaces of dacron biomaterials of each group were evaluated by confocal laser microscopy and scanning electron microscopy after incubating 6h, 16h, 24h, 30h, and 48h. Results The thickness and number of staphylococcus aureus biofilm on dacron biomaterials surfaces increased significantly with time dependence in control group. The thickness and number of staphylococcus aureus biofilm in group A were less than those in group B and control group at each time points （P〈0. 05）. The thickness and number in group B were significantly decreased than those in control group （P 〈 0. 05）. Conclusion The study shows that Aur can effectively inhibit the formation of staphylococcus aureus biofilm on dacron biomaterials surfaces with dose dependence.