scholarly journals Virulence characteristics of community-associated Staphylococcus aureus and in vitro activities of moxifloxacin alone and in combination against community-associated and healthcare-associated meticillin-resistant and -susceptible S. aureus

2008 ◽  
Vol 57 (4) ◽  
pp. 452-456 ◽  
Author(s):  
Ellie J. C. Goldstein ◽  
Diane M. Citron ◽  
Yumi A. Warren ◽  
Kerin L. Tyrrell ◽  
Michael J. Rybak
Keyword(s):  
Staphylococcus Aureus ◽  
Inhibitory Concentration ◽  
Inducible Clindamycin Resistance ◽  
Mrsa Strains ◽  
Healthcare Associated ◽  
Concentration Indices ◽  
Panton Valentine Leukocidin

The increasing prevalence of community-associated meticillin-resistant Staphylococcus aureus (CA-MRSA) poses a challenge for antimicrobial therapy of skin and soft tissue infections (SSTIs). To determine whether another antimicrobial agent might enhance the activity of moxifloxacin against CA-MRSA, this study analysed its activity alone and in chequerboard combination with doxycycline, rifampicin, clindamycin, trimethoprim, sulfamethoxazole/trimethoprim (SXT) and vancomycin against recent SSTI clinical isolates, and also characterized the isolates for Panton–Valentine leukocidin (PVL), agr groups, staphylococcal cassette chromosome mec (SSCmec) types and δ-haemolysin production. For comparison, 25 strains of outpatient meticillin-susceptible S. aureus (MSSA), 24 strains of healthcare-associated (HA)-MRSA and six historical strains of vancomycin-intermediate S. aureus (VISA) were included. It was found that 21/25 CA-MRSA strains tested were PVL-positive, SSCmec type 4 and agr type 1, whilst 4/25 were PVL-negative, SSCmec type 2 and agr type 2. Two of the agr type 2 strains were negative for δ-haemolysin but all other strains were positive. Moxifloxacin MIC50/90 values (μg ml−1) were 1/8 for CA-MRSA, 4/32 for HA-MRSA and ≤0.03/1 for MSSA and MIC50 of 2 for VISA. The D-test for inducible clindamycin resistance was positive for 3/27 CA-MRSA, 5/14 HA-MRSA and none of the MSSA isolates. In chequerboard studies, fractional inhibitory concentration indices (FICIs) showed that most interactions were additive or indifferent (FICI value >0.5 to ≤2) as follows: rifampicin 43/52 strains, clindamycin 44/44, SXT 44/47, trimethoprim 41/42 and vancomycin 37/43. The FICI values for doxycycline were 3–6 for 32/34 strains, indicating antagonism, suggesting that it should not be used in combination with moxifloxacin.

scholarly journals Methicillin-Resistant Staphylococcus aureus Recovered from Healthcare- and Community-Associated Infections in Egypt

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
Mohamed Abdel-Maksoud ◽  
Mona El-Shokry ◽  
Ghada Ismail ◽  
Soad Hafez ◽  
Amani El-Kholy ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Infection Control ◽  
Continuous Monitoring ◽  
Inhibitory Concentration ◽  
Methicillin Resistant ◽  
Inducible Clindamycin Resistance ◽  
The Past ◽  
Mrsa Strains ◽  
Healthcare Associated ◽  
Over Time

Background. Methicillin-resistant Staphylococcus aureus (MRSA) has created significant epidemiological, infection-control, and therapeutic management challenges during the past three decades. Aim. To analyze the pattern of resistance of healthcare- and community-associated MRSA in Egypt and the trend of resistance of HA-MRSA over time (2005–2013). Methods. MRSA isolates were recovered from healthcare-associated (HA) and community-associated (CA) Staphylococcus aureus (S. aureus) infections. They were tested against 11 antimicrobial discs and the minimal inhibitory concentration (MIC) of vancomycin was determined. Inducible clindamycin resistance (iMLSB) was also screened using D-test. Findings. Of 631 S. aureus, MRSA was identified in 343 (76.6%) and 21 (11.5%) of HA and CA S. aureus isolates, respectively. The proportion of HA-MRSA increased significantly from 48.6% in 2005 to 86.8% in 2013 (p value < 0.001). Multidrug resistance (MDR) was observed in 85.8% of HA-MRSA and 48.6% of CA-MRSA. Vancomycin intermediate resistant S. aureus (VISA) was detected in 1.2% of HA-MRSA and none was detected in CA-MRSA. Among HA-MRSA strains, 5.3% showed iMLSB compared to 9.5% among CA-MRSA. Conclusion. The upsurge of the prevalence rates of HA-MRSA over time is alarming and urges for an effective infection control strategy and continuous monitoring of antimicrobial use.

scholarly journals Ceftobiprole EfficacyIn Vitroagainst Panton-Valentine Leukocidin Production andIn Vivoagainst Community-Associated Methicillin-Resistant Staphylococcus aureus Osteomyelitis in Rabbits

2012 ◽  
Vol 56 (12) ◽  
pp. 6291-6297 ◽  
Author(s):  
Azzam Saleh-Mghir ◽  
Oana Dumitrescu ◽  
Aurélien Dinh ◽  
Yassine Boutrad ◽  
Laurent Massias ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant ◽  
Content Type ◽  
The Mean ◽  
Mrsa Strains ◽  
Time Kill ◽  
Panton Valentine Leukocidin ◽  
Valentine Leukocidin

ABSTRACTCommunity-associated methicillin-resistantStaphylococcus aureus(CA-MRSA) can cause osteomyelitis with severe sepsis and/or local complications in which a Panton-Valentine leukocidin (PVL) role is suspected.In vitrosub-MIC antibiotic effects on growth and PVL production by 11 PVL+MRSA strains, including the major CA-MRSA clones (USA300, including the LAC strain; USA400; and USA1000), and 11 PVL+methicillin-susceptibleS. aureus(MSSA) strains were tested in microplate culture. Time-kill analyses with ceftobiprole at its MIC were also run with LAC. Efficacies of ceftobiprole (40 mg/kg of body weight subcutaneously [s.c.] four times a day [q.i.d.]) or vancomycin (60 mg/kg intramuscularly [i.m.] twice a day [b.i.d.]) alone or combined with rifampin (10 mg/kg b.i.d.) against rabbit CA-MRSA osteomyelitis, induced by tibial injection of 3.4 × 107CFU of LAC, were compared. Treatment, started 14 days postinoculation, lasted 14 days.In vitro, 6/11 strains cultured with sub-MICs of ceftobiprole produced 1.6- to 4.8-fold more PVL than did the controls, with no link to specific clones. Rifampin decreased PVL production by all tested strains. In time-kill analyses at the LAC MIC (0.75 mg/liter), PVL production rose transiently at 6 and 8 h and then declined 2-fold at 16 h, concomitant with a 2-log10-CFU-count decrease.In vivo, the mean log10CFU/g of bone for ceftobiprole (1.44 ± 0.40) was significantly lower than that for vancomycin (2.37 ± 1.22) (P= 0.034), with 7/10 versus 5/11 bones sterilized, respectively. Combination with rifampin enhanced ceftobiprole (1.16 ± 0.04 CFU/g of bone [P= 0.056], 11/11 sterile bones) and vancomycin (1.23 ± 0.06 CFU/g [P= 0.011], 11/11 sterile bones) efficacies. Ceftobiprole bactericidal activity and the rifampin anti-PVL effect could play a role in these findings, which should be of interest for treating CA-MRSA osteomyelitis.

scholarly journals Efficiency of Antimicrobial Photodynamic Therapy with Photodithazine® on MSSA and MRSA Strains

Antibiotics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 869
Author(s):  
Beatriz Müller Nunes Souza ◽  
Juliana Guerra Pinto ◽  
André Henrique Correia Pereira ◽  
Alejandro Guillermo Miñán ◽  
Juliana Ferreira-Strixino
Keyword(s):  
Staphylococcus Aureus ◽  
Photodynamic Therapy ◽  
Antimicrobial Photodynamic Therapy ◽  
Bacterial Inactivation ◽  
Bacterial Reduction ◽  
Complete Inactivation ◽  
Opportunistic Bacteria ◽  
Significant Difference ◽  
Mrsa Strains

Staphylococccus aureus is a ubiquitous and opportunistic bacteria associated with high mortality rates. Antimicrobial photodynamic therapy (aPDT) is based on the application of a light source and a photosensitizer that can interact with molecular oxygen, forming Reactive Oxygen Species (ROS) that result in bacterial inactivation. This study aimed to analyze, in vitro, the action of aPDT with Photodithazine® (PDZ) in methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) strains. The strains were incubated with PDZ at 25, 50, 75, and 100 mg/L for 15 min and irradiated with fluences of 25, 50, and 100 J/cm2. The internalization of PDZ was evaluated by confocal microscopy, the bacterial growth by counting the number of colony-forming units, as well as the bacterial metabolic activity post-aPDT and the production of ROS. In both strains, the photosensitizer was internalized; the production of ROS increased when the aPDT was applied; there was a bacterial reduction compared to the control at all the evaluated fluences and concentrations; and, in most parameters, it was obtained complete inactivation with significant difference (p < 0.05). The implementation of aPDT with PDZ in clinical strains of S. aureus has resulted in its complete inactivation, including the MRSA strains.

scholarly journals Effect of Different Fermentation Condition on Estimated Glycemic Index, In Vitro Starch Digestibility, and Textural and Sensory Properties of Sourdough Bread

Foods ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 514
Author(s):  
Hilal Demirkesen-Bicak ◽  
Muhammet Arici ◽  
Mustafa Yaman ◽  
Salih Karasu ◽  
Osman Sagdic
Keyword(s):  
Glycemic Index ◽  
Sensory Properties ◽  
Starch Digestibility ◽  
In Vitro Starch Digestibility ◽  
Whole Wheat ◽  
Sourdough Bread ◽  
Estimated Glycemic Index

This study aimed to evaluate the influence of sourdough fermentation on the estimated glycemic index (eGI), in vitro starch digestibility, and textural and sensory properties of eight experimentally prepared sourdough breads. Wheat and whole wheat flour bread samples were produced under different fermentation conditions (25 °C and 30 °C) and fermentation methods (type-1 and type-2). In type-1 fermentation, sourdough was obtained via spontaneous fermentation. Indigenous strains (Lactobacillus brevis ELB99, Lactiplantibacillus plantarum ELB75, and Saccharomyces cerevisiae TGM55) were used for type-2 fermentation. Fermentation type and temperature significantly affected eGI, the hydrolysis index (HI), the starch fraction, and the textural properties of the samples (p < 0.05). The resistant starch (RS) content increased after fermentation, while rapidly digestible starch (RDS), HI, and eGI decreased. RS values were significantly higher in type-2 than in type-1 at the same temperature for both flour types (p < 0.05). At 25 °C, RS values were higher in both fermentation types. In the white flour samples, eGI values were in the range of 60.8–78.94 and 62.10–78.94 for type-1 and type-2, respectively. The effect of fermentation type on eGI was insignificant (p < 0.05). In the whole flour samples, fermentation type and temperature significantly affected eGI (p < 0.05). The greatest eGI decreases were in whole wheat sourdough bread at 30 °C using type-2 (29.74%). The 30 °C and type-2 samples showed lower hardness and higher specific volume. This study suggests that fermentation type and temperature could affect the eGI and the textural and sensory properties of sourdough bread, and these factors should be considered during bread production. The findings also support the consumption of wheat and whole wheat breads produced by type-2 fermentation due to higher RS and slowly digestible starch (SDS) and lower RDS and eGI values.

scholarly journals First Report ofEurycoma longifoliaJack Root Extract Causing Relaxation of Aortic Rings in Rats

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Bae Huey Tee ◽  
See Ziau Hoe ◽  
Swee Hung Cheah ◽  
Sau Kuen Lam
Keyword(s):  
Erectile Function ◽  
Receptor Activation ◽  
Root Extract ◽  
Ang Ii ◽  
Angiotensin I ◽  
Eurycoma Longifolia ◽  
Vasodilatory Effect

AlthoughEurycoma longifoliahas been studied for erectile function, the blood pressure- (BP-) lowering effect has yet to be verified. Hence, this study aims at investigating the BP-lowering properties of the plant with a view to develop an antihypertensive agent that could also preserve erectile function. Ethanolic root extract was partitioned by hexane, dichloromethane (DCM), ethyl acetate, butanol, and water. The DCM fraction, found to be potent in relaxing phenylephrine- (PE-) precontracted rat aortic rings, was further purified by column chromatography. Subfraction DCM-II, being the most active in relaxing aortae, was studied for effects on the renin-angiotensin and kallikrein-kinin systems in aortic rings. The effect of DCM-II on angiotensin-converting enzyme (ACE) activity was also evaluatedin vitro. Results showed that DCM-II reduced (p<0.05) the contractions evoked by angiotensin I and angiotensin II (Ang II). In PE-precontracted rings treated with DCM-II, the Ang II-induced contraction was attenuated (p<0.05) while bradykinin- (BK-) induced relaxation enhanced (p<0.001).In vitro, DCM-II inhibited (p<0.001) the activity of ACE. These data demonstrate that the vasodilatory effect of DCM-II appears to be mediatedviainhibition of Ang II type 1 receptor and ACE as well as enhancement of Ang II type 2 receptor activation and BK activity.

scholarly journals Differential Activation of CD8+Tumor-Specific Tc1 and Tc2 Cells by an IL-10-Producing Murine Plasmacytoma

1998 ◽  
Vol 6 (3-4) ◽  
pp. 331-342 ◽  
Author(s):  
Christoph Specht ◽  
Hans-Gerd Pauels ◽  
Christian Becker ◽  
Eckehart Kölsch
Keyword(s):  
T Cells ◽  
Immune Responses ◽  
Tumor Cells ◽  
T Cell Subsets ◽  
Early Stages ◽  
Specific Tolerance

The involvement of counteractiveCD8+T-cell subsets during tumor-specific immune responses was analyzed in a syngeneic murine plasmacytoma model.CD8+Tc cells against the immunogenic IL-10-producing BALB/c plasmacytoma ADJ-PC-5 can be easily induced by immunization of BALB/c mice with X-irradiated ADJ-PC-5 tumor cellsin vivoandin vitro. However, the failure of recipient mice to mount a protective Tc response against the tumor during early stages of a real or simulated tumor growth is not due to immunological ignorance, but depends on the induction of tumor-specific tolerance, involving a population of tumorinducedCD8+T cells that are able to inhibit the generation of tumor-specific Tc cells in a primary ADJ-PC-5-specific MLTC, using IFN-γas a suppressive factor. Whereas most longterm cultivated CD8+ADJ-PC-5-specific Tc lines produce type-1 cytokines on stimulation, at least two of them, which were derived from a primary MLTC, display a type-2 cytokine spectrum. Furthermore, the primaryin vitroTc response against ADJ-PC-5 cells shows characteristics of a Tc2 response. The Tc response is strictly depending on tumor-derived IL-10.CD8+Tc cells that are induced in a primary MLTC do not produce IFN-γ, and the tumor-specific Tc response is enhanced by IL-4 but suppressed by IFN-γor IL-12. In contrast, ADJ-PC- 5-specificCD8+Tc cells from immunized mice are IFN-γproducing Tc1 cells. Since the primaryin vitroTc response against the tumor is suppressed even by the smallest numbers of irradiated ADJ-PC-5-specific Tc1 cells via IFN-γthese Tc1 cells behave similar to the suppressiveCD8+T cells that are induced during early stages of ADJ-PC-5 tumorigenesis.

scholarly journals Evaluation of Ceftaroline Alone and in Combination against Biofilm-Producing Methicillin-Resistant Staphylococcus aureus with Reduced Susceptibility to Daptomycin and Vancomycin in anIn VitroPharmacokinetic/Pharmacodynamic Model

2015 ◽  
Vol 59 (8) ◽  
pp. 4497-4503 ◽  
Author(s):  
Katie E. Barber ◽  
Jordan R. Smith ◽  
Cortney E. Ireland ◽  
Blaise R. Boles ◽  
Warren E. Rose ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Medical Device ◽  
Bloodstream Infections ◽  
Methicillin Resistant ◽  
Content Type ◽  
Elimination Half ◽  
Antimicrobial Protection ◽  
Mrsa Strains ◽  
Post Hoc

ABSTRACTAnnually, medical device infections are associated with >250,000 catheter-associated bloodstream infections (CLABSI), with up to 25% mortality.Staphylococcus aureus, a primary pathogen in these infections, is capable of biofilm production, allowing organism persistence in harsh environments, offering antimicrobial protection. With increases inS. aureusisolates with reduced susceptibility to current agents, ceftaroline (CPT) offers a therapeutic alternative. Therefore, we evaluated whether CPT would have a role against biofilm-producing methicillin-resistantS. aureus(MRSA), including those with decreased susceptibilities to alternative agents. In this study, we investigated CPT activity alone or combined with daptomycin (DAP) or rifampin (RIF) against 3 clinical biofilm-producing MRSA strains in anin vitrobiofilm pharmacokinetic/pharmacodynamic (PK/PD) model. Simulated antimicrobial regimens were as follows: 600 mg of CPT every 8 h (q8h) (free maximum concentration of drug [fCmax], 17.04 mg/liter; elimination half-life [t1/2], 2.66 h), 12 mg/kg of body weight/day of DAP (fCmax, 14.7 mg/liter;t1/2, 8 h), and 450 mg of RIF q12h (fCmax, 3.5 mg/liter;t1/2, 3.4 h), CPT plus DAP, and CPT plus RIF. Samples were obtained and plated to determine colony counts. Differences in log10CFU/cm2were evaluated by analysis of variance with Tukey'spost hoctest. The strains were CPT and vancomycin susceptible and DAP nonsusceptible (DNS). CPT displayed activity throughout the experiment. DAP demonstrated initial activity with regrowth at 24 h in all strains. RIF was comparable to the drug-free control, and little benefit was observed when combined with CPT. CPT plus DAP displayed potent activity, with an average log10CFU/cm2reduction of 3.33 ± 1.01 from baseline. CPT demonstrated activity against biofilm-producing DNS MRSA. CPT plus DAP displayed therapeutic enhancement over monotherapy, providing a potential option for difficult-to-treat medical device infections.

In-Vitro Studies on the Sensitivity of Staphylococcus aureus to Some Ethno-Medicinal Preparations Sold around Kano, Nigeria

2011 ◽  
Vol 4 (1) ◽  
pp. 22-25 ◽  
Author(s):  
M Bashir ◽  
I Yusuf ◽  
AS Kutama
Keyword(s):  
Staphylococcus Aureus ◽  
Antibacterial Activity ◽  
Minimum Inhibitory Concentration ◽  
Inhibitory Concentration ◽  
Test Organism ◽  
Ethanolic Extract ◽  
Screening Tests ◽  
Phytochemical Screening ◽  
Herbal Preparations

Five traditional herbal preparations were sampled between May-June, 2009 in Kano. The samples were investigated for invitro antibacterial activities against clinical isolates of Staphylococcus aureus. Likewise, phytochemical screening tests were conducted to determine some of the phytochemicals present in the ethanolic and water extracts of the samples. Various concentrations of the extracts were prepared using serial doubling dilutions (5000=l/ml, 2500=g/ml, 1250=g/ml, 625=g/ml and 312.5=g/ml). All the test extracts showed slight antibacterial activity against the test organism, with ethanolic extract of sample E having the highest zone diameter of inhibition, while sample H had the lowest diameter of inhibition. The standard antibiotic disc (Gentamicin) had demonstrated the highest activity on the test organisms. The results of the Phytochemical screening revealed the presence of steroid in all the samples, tannin in samples A, C, D and E, reducing sugars in sample A, D and E respectively. The result of the minimum inhibitory concentration (MIC) was found to be above 312.5=g/ml for samples C, D and E. Keywords: Staphylococcus aureus, Herbal preparations, antibacterial activity, Phytochemical screening and minimum inhibitory concentration.

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