Relatedness between the coagulase gene 3'-end region and coagulase serotypes among Staphylococcus aureus strains

The 3'-end region of the coagulase gene from 22 strains of Staphylococcus aureus including 10 standard serotype strains was sequenced, and five subgroups with 4-8 tandem repeating units were distinguished among the tested strains. Phylogenetic analysis of the 3'-end region of the coagulase gene indicated that strains belonging to the same serotype were clustered in the same branch. A phylogenetic tree of the deduced amino acid sequences revealed that the C-terminal region might not be responsible for the epitope of the coagulase protein.     

Improved methods for detection and serotyping of coagulase from Staphylococcus aureus

Improved methods for detection and serotyping of staphylocoagulase were concomitantly devised. We devised an improved method for detection of coagulase activity on agarose film in the same manner as single radial immunodiffusion. The amounts of reagents required for detection of coagulase on agarose film were successfully diminished by adding polyethylene glycol (PEG) to the original formula described by Boothby et al. Using microplates in another improved method for coagulase serotyping, the amount of reaction fluid required was considerably less compared with the conventional tube method. PEG was found to be also effective to increase the efficacy of coagulase serotyping. In the presence or absence of anti-coagulase antisera, culture supernatants of staphylococcal strain grown in brain heart infusion broth were incubated with the reaction fluid containing bovine fibrinogen, rabbit plasma, 6-amino caproic acid, polyethylene glycol 6,000. Coagulase activity was visualized as a turbid mass formed in the wells. Turbid mass formation due to coagulase activity was type-specifically inhibited in the presence of type-specific antisera. Detailed procedures of the methods are precisely described with some preliminary results obtained by the methods.     

Characteristics of defective strains of methicillin resistance Staphylococcus aureus that do not produce coagulase or CF

The aim of the study was to estimate frequency of coagulase-negative and CF-negative strains among methicillin-resistant Staphylococcus aureus (MRSA) and to assess their homogeneicity in respect of genotype, phagotype and drug resistance pattern. A total of 186 MRSA strains collected from different hospitals in Gdańsk region were studied. Gens: nuc, mecA, and coa were identified by PCR method. The coagulase tube test for staphylocoagulase and the slide test for clumping factor were used. Coagulase-negative and CF-negative MRSA strains were confirmed by PCR-RFLP method of coa gene; phage typing and drug resistance pattern were evaluated by disc diffusion test. The results of the study showed low frequency of both coagulase-negative and CF-negative MRSA strains (7.25% and 3.76% respectively). Among MRSA population tested the simultaneous occurrence of the strains lacking coagulase and clumping factor was not observed. All coagulase negative MRSA had coagulase gene (coa) and differed from CF-negative strains in respect of coa gene.     

Circadian rhythms in epidermal mitotic activity

Virchows Archiv B Cell Pathology - Circadian variations in mitotic index, mitotic rate (cells entering mitosis per hour) and mitotic duration were investigated in the epidermis of the back and ear...     

铜绿假单胞菌抗菌物质对耐甲氧西林金黄色葡萄球菌的抑菌活性研究

目的观察铜绿假单胞菌抗菌物质对耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcusaureus,MRSA)的体外抑菌活性。方法用交叉划线接种方法进行铜绿假单胞菌对32株耐甲氧西林金葡菌的体外抗菌活性的测定。结果铜绿假单胞菌抗菌物质对MRSA的体外抑菌活性良好,产生色素的菌株的抗菌活性最好,15株铜绿假单胞菌中,7株产蓝绿色色素的铜绿假单胞菌,对MRSA的抑制率均达到了100%,平均抑菌带的宽度为37.7 mm。结论铜绿假单胞菌抗菌物质对32株MRSA具有较强的抗菌活性,无疑对MRSA感染的抗菌药物研制方面开辟了一条新的途径。这是国内的首次研究报道。     

The antibacterial activity of vancomycin towards Staphylococcus aureus under aerobic and anaerobic conditions

AIMS: To investigate the antibacterial efficacy of vancomycin towards Staphylococcus aureus under aerobic and anaerobic conditions, and to assess the influence of oxygen on the duration of the post-antibiotic effect (PAE) after exposure to vancomycin. METHODS AND RESULTS: Culture-based techniques and flow cytometric measurements of 5-cyano-2,3-ditolyl tetrazolium chloride (an indicator of redox activity) and the membrane potential-sensitive fluorophore Sytox Green, were used to test four staphylococcal strains. The MICs for all strains, and the duration of PAE, were similar whether tested with or without oxygen. However, a fivefold logarithmic reduction in cell counts was observed in 10-15 h aerobically, depending on strain, compared with longer than 60 h in an anaerobic environment. Flow cytometric data correlated well with counts of colony-forming units under both aerobic and anaerobic conditions. CONCLUSIONS: The death rate of Staph. aureus exposed to vancomycin was greater in the presence of oxygen, although MIC values and PAE durations were similar whether tested aerobically or anaerobically. Also, flow cytometry provided a rapid and sensitive alternative to plate counts for the assessment of antibiotics in oxygen-free conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: This study underlines the need for further anaerobic testing using different strain/antibiotic combinations, the results of which will have clinical significance due to the anaerobic nature of some sites of infection.     

凝固酶阴性葡萄球菌菌谱与药敏谱调查

目的了解中山大学附属第三医院临床分离凝固酶阴性葡萄球菌（CNS）的菌种构成与耐药性。方法采用MicroScan WalkAway-40全自动微生物鉴定仪及配套阳性菌药敏复合板进行菌种鉴定与药敏试验,nitrocefin法测定β-内酰胺酶。结果表皮葡萄球菌与溶血葡萄球菌共占CNS的70．4％;甲氧西林耐药株（MRCNS）与甲氧西林敏感株（MSCNS）各占77．8％、22．2％;药敏试验结果提示MRCNS仅对万古霉素、呋喃妥因敏感,MSCNS对大多数抗生素敏感,未检出万古霉素耐药与中介株;β-内酰胺酶在MRCNS、MSCNS中的检出率分别为91．7％、78．1％。结论临床分离的CNS以表皮葡萄球菌和溶血葡萄球菌为主,MRCNS多重耐药现象严重,宜密切监测CNS的分离状况与耐药性,并严格限制万古霉素在临床上的应用,以避免耐万古霉素CNS的出现与流行。     

Effect of temperature on antibacterial activity of lidocaine to Staphylococcus aureus and Pseudomonas aeruginosa

The effect of temperature on the antibacterial activity of lidocaine to Staphylococcus aureus and Pseudomonas aeruginosa was investigated in vitro. At 10 C at which S. aureus organisms do not grow and might be metabolically inactive, the antibacterial activity of lidocaine to S. aureus was not observed in a concentration of 1%, which was quite antibacterial to S. aureus at 37 C. On the other hand, at 40 C a conspicuously increased antibacterial activity to S. aureus of lidocaine was observed in a concentration of 0.25% which was not antibacterial to S. aureus organisms at 37 C. Similar results were obtained when P. aeruginosa organisms were examined in place of S. aureus, although P. aeruginosa was found to be less susceptible to lidocaine than S. aureus. The clinical significance of the thermal effect on the antibacterial activity of lidocaine was discussed in brief.     

Liposome containing cinnamon oil with antibacterial activity against methicillin-resistant Staphylococcus aureus biofilm

The global burden of bacterial disease remains high and is set against a backdrop of increasing antimicrobial resistance. There is a pressing need for highly effective and natural antibacterial agents. In this work, the anti-biofilm effect of cinnamon oil on methicillin-resistant Staphylococcus aureus was evaluated. Then, cinnamon oil was encapsulated in liposomes to enhance its chemical stability. The anti-biofilm activities of the liposome-encapsulated cinnamon oil against MRSA biofilms on stainless steel, gauze, nylon membrane and non-woven fabrics were evaluated by colony forming unit determination. Scanning electron microscopy and laser scanning confocal microscopy analyses were employed to observe the morphological changes in MRSA biofilms treated with the encapsulated cinnamon oil. As a natural and safe spice, the cinnamon oil exhibited a satisfactory antibacterial performance on MRSA and its biofilms. The application of liposomes further improves the stability of antimicrobial agents and extends the action time.     

Synthesis and evaluation of amphiphilic cationic quinine-derived for antibacterial activity against methicillin-resistant Staphylococcus aureus

Several representative amphiphilic cationic quinine-derived have been synthesized and evaluated against methicillin- resistant Staphylococcus aureus. This is the first reported antibacterial activity of this class of compounds. In vitro the minimal inhibitory concentration values of the best compound Q7 ranged from 0.4 to 1.6 microg/mL (MBC<3.2 microg/mL).     

Piperazinyl-linked fluoroquinolone dimers possessing potent antibacterial activity against drug-resistant strains of Staphylococcus aureus

The synthesis of symmetric and asymmetric piperazinyl-linked dimers of the fluoroquinolone class of antibiotics is described. Specific dimers are shown to possess potent antibacterial activity against drug-resistant strains of Staphylococcus aureus, including strains possessing resistance due to the NorA multidrug efflux pump and a mutation in the quinolone resistance-determining region of topoisomerase IV.     

Antimicrobial resistance in Staphylococcus aureus

Recognized since 1883 as a common cause of infection, Staphylococcus aureus' preantimicrobial-era bacteremia mortality rate was 82%. The mortality of that era threatens to return as evidence of growing vancomycin resistance undermines the utility of vancomycin therapy. Successful treatment of S. aureus infections requires knowledge of its antimicrobial resistance capacity.     

Staphylococcus aureus ClpC is required for stress resistance, aconitase activity, growth recovery, and death

The ability of Staphylococcus aureus to adapt to various conditions of stress is the result of a complex regulatory response. Previously, it has been demonstrated that Clp homologues are important for a variety of stress conditions, and our laboratory has shown that a clpC homologue was highly expressed in the S. aureus strain DSM20231 during biofilm formation relative to expression in planktonic cells. Persistence and long-term survival are a hallmark of biofilm-associated staphylococcal infections, as cure frequently fails even in the presence of bactericidal antimicrobials. To determine the role of clpC in this context, we performed metabolic, gene expression, and long-term growth and survival analyses of DSM20231 as well as an isogenic clpC allelic-replacement mutant, a sigB mutant, and a clpC sigB double mutant. As expected, the clpC mutant showed increased sensitivity to oxidative and heat stresses. Unanticipated, however, was the reduced expression of the tricarboxylic acid (TCA) cycle gene citB (encoding aconitase), resulting in the loss of aconitase activity and preventing the catabolization of acetate during the stationary phase. clpC inactivation abolished post-stationary-phase recovery but also resulted in significantly enhanced stationary-phase survival compared to that of the wild-type strain. These data demonstrate the critical role of the ClpC ATPase in regulating the TCA cycle and implicate ClpC as being important for recovery from the stationary phase and also for entering the death phase. Understanding the stationary- and post-stationary-phase recovery in S. aureus may have important clinical implications, as little is known about the mechanisms of long-term persistence of chronic S. aureus infections associated with formation of biofilms.     

Solid-phase synthesis and antibacterial activity of hydroxycinnamic acid amides and analogues against methicillin-resistant Staphylococcus aureus and vancomycin-resistant S. aureus

A library of hydroxycinnamic acid amides (HCAAs) and analogues were synthesized using solid-phase synthesis technique. These compounds were screened for antibacterial against methicillin-resistant Staphylococcus aureus (MRSA) (11 strains) and vancomycin-resistant S. aureus (VRSA) (4 strains). Dihydrocaffeoyl analogues showed activity against VRSA which were better than the reference drugs, vancomycin and oxacillin. These compounds also exhibited antibacterial activity against MRSA, which were more potent than oxacillin.     

Sophoraflavanone G from sophora pachycarpa enhanced the antibacterial activity of gentamycin against Staphylococcus aureus

In this study the enhancement effect of Sophora pachycarpa roots' acetone extract on the antibacterial activity of gentamycin was evaluated against Staphylococcus aureus. Disc diffusion and broth dilution methods were used to determine the antibacterial activity of gentamycin in the absence and presence of plant extract and its various fractions separated by TLC. A clinical isolate of S. aureus was used as test strain. The active component of the plant extract involved in enhancement of gentamycin's activity had Rf = 0.72 on a TLC plate. The spectral data (1H NMR, 13C NMR) of this compound revealed that this compound was 5,7,2',4'-tetrahydroxy-8-lavandulylflavanone (sophoraflavanone G), previously isolated from Sophora exigua. In the presence of 0.03 microg/ mL of sophoraflavanone G the MIC value of gentamycin for S. aureus decreased from 32 to 8 microg/mL (a four-fold decrease). These results signify that the ultra-low concentration of sophoraflavanone G potentiates the antimicrobial action of gentamycin suggesting a possible utilization of this compound in combination therapy against Staphylococcus aureus.