Maysa Mahfoud - Academia.edu (original) (raw)

Papers by Maysa Mahfoud

Pharmacognosy Communications, 2017

Objective: To evaluate the antimicrobial properties of Thymus vulgaris against seven pathogenic f... more Objective: To evaluate the antimicrobial properties of Thymus vulgaris against seven pathogenic fungi strains and its cytotoxic effect on a human breast cancer cell line (MDA-MB-231) Methods: The susceptibility test was carried out in terms of by determining minimal inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) using micro-dilution methods and additional end point by using MTS chromogenic assay. Cytotoxicity activity was assessed using MTT assay, the viability and the IC50 were used to evaluate this test. Results: All tested fungal strains were sensitive to the (Thymus vulgaris essential oil) TEO and this inhibitory effect is dose-dependent. A remarkable (p<0.001) inhibitory effect at concentrations 2.5-10mg/ml for all tested organisms comparable with control was found. The MIC 50 values ranged between 0.5 to 5mg/ml. The MFC values varied from 2.5-10 mg/mL and were equal to MIC values for majority of the tested organisms. As far as the antifungal activity is concern, out of the seven strains tested, Candida kefyr exhibited the highest sensitivity with minimal inhibition growth 2.5mg/ml whereas, Aspergillus niger exhibited the lowest inhibition ≥10mg/ml. Thymus vulgaris oil inhibited proliferation of MDA-MD-231 cancer cells in a time-and dose dependent manner. IC 50 value of the complex was found to be time dependent. At 24h treatment, the IC 50 values ranging between 108-115μg/ml, while at 48h treatment the values were between 71-78μg/ml against cancer cell. Conclusion: Thymus vulgaris essential oil exhibited significant antifungal and cytotoxic effects on living cells. Therefore, it can be used as alternative antifungal natural substances and also play a significant role in discovery of the new drugs.

Journal of Biological Chemistry, Mar 1, 2006

MspA is the major porin of Mycobacterium smegmatis mediating the exchange of hydrophilic solutes ... more MspA is the major porin of Mycobacterium smegmatis mediating the exchange of hydrophilic solutes across the outer membrane (OM). It is the prototype of a new family of octameric porins with a single central channel of 9.6 nm in length and consists of two hydrophobic ␤-barrels of 3.7 nm in length and a more hydrophilic, globular rim domain. The length of the hydrophobic domain of MspA does not match the thicknesses of mycobacterial OMs of 5-12 nm as derived from electron micrographs. Further, the membrane topology of MspA is unknown as it is for any other mycobacterial OM protein. We used MspA as a molecular ruler to define the boundaries of the OM of M. smegmatis by surface labeling of single cysteine mutants. Seventeen mutants covered the surface of the rim domain and were biotinylated with a membrane-impermeable reagent. The label efficiencies in vitro were remarkably similar to the predicted accessibilities of the cysteines. By contrast, six of these mutants were protected from biotinylation in M. smegmatis cells. Tryptophan 21 defines a horizontal plane that dissects the surfaceexposed versus the membrane-protected residues of MspA. The 8 phenylalanines at position 99 form a ring at the periplasmic end of the hydrophobic ␤-barrel domain. These results indicated that (i) the membrane boundaries of MspA are defined by aromatic girdles as in porins of Gram-negative bacteria and (ii) loops and a 3.4-nmlong part of the hydrophilic rim domain are embedded into the OM of M. smegmatis. This is the first report suggesting that elements other than hydrophobic ␣-helices or ␤-sheets are integrated into a lipid membrane.

Journal of Bacteriology, Mar 15, 2007

Phosphorus is an essential nutrient, but how phosphates cross the mycobacterial cell wall is unkn... more Phosphorus is an essential nutrient, but how phosphates cross the mycobacterial cell wall is unknown. Phosphatase activity in whole cells of Mycobacterium smegmatis was significantly lower than that in lysed cells, indicating that access to the substrate was restricted. The loss of the outer membrane (OM) porin MspA also reduced the phosphatase activity in whole cells compared to that in lysed cells. A similar result was obtained for M. smegmatis that overexpressed endogenous alkaline phosphatase, indicating that PhoA is not a surface protein, contrary to a previous report. The uptake of phosphate by a mutant lacking the porins MspA and MspC was twofold lower than that by wild-type M. smegmatis. Strikingly, the loss of these porins resulted in a severe growth defect of M. smegmatis on low-phosphate plates. We concluded that the OM of M. smegmatis represents a permeability barrier for phosphates and that Msp porins are the only OM channels for the diffusion of phosphate in M. smegmatis. However, phosphate diffusion through Msp pores is rather inefficient as shown by the 10-fold lower permeability of M. smegmatis for phosphate compared to that for glucose. This is likely due to the negative charges in the constriction zone of Msp porins. The phosphatase activity in whole cells of Mycobacterium bovis BCG was significantly less than that in lysed cells, indicating a similar uptake pathway for phosphates in slow-growing mycobacteria. However, porins that could mediate the diffusion of phosphates across the OM of M. bovis BCG and Mycobacterium tuberculosis are unknown.

Archives of Ecotoxicology, Mar 31, 2021

The emergence of antibiotic resistant microorganism strains has become a critical concern in the ... more The emergence of antibiotic resistant microorganism strains has become a critical concern in the treatment of infectious diseases and makes the search of an alternative therapy a must. The study was designed to evaluate the in vitro antimicrobial activities of the Moringa peregrina (MP) leave (MPL) and seed (MPS) extracts. Antimicrobial assays were performed using a microplate growth inhibition assay against 11 multidrug-resistant (MDR) strains. Following qualitative analysis, dose-response assays were performed using the MTT colorimetric assay. The results showed a strong correlation between the MPL and MPS extract concentration and growth inhibition (P<0.001). MP extract revealed a remarkable antimicrobial effect and inhibited the growth and survival of MDR pathogens which include Escherichia coli; Pseudomonas aeruginosa; Klebsiella pneumonia; Acinetobacter baumannii; Staphylococcus aureus between (88.6-94.7 %) and between (62.3-88.7%) against Candida Kefyer; Candida parapsilosis; Candida albicans; Candida glabrata; Aspergillus flavus and Fusarium oxysporum. MIC50 ranging from ≤6.25 to 25 mg/mL. Acinetobacter baumannii and Pseudomonas aeruginosa were the most susceptible to MP extracts (MIC50 < 6.25 mg/mL). These results support the use of MP in Arab traditional medicine as natural antimicrobial agents. Additionally, the use of such naturally occurring adjuvant derived from medicinal plants can be used as an adjuvant with synthetic antibiotics to combat bacterial resistance and to enhance the antibacterial potential. Further studies are recommended on isolation and purification of novel antimicrobial molecules to treat the infections caused by microbes.

Journal of global antimicrobial resistance, Sep 1, 2017

Scorpion venoms are a rich source of bioactive peptides with promising clinical value that may le... more Scorpion venoms are a rich source of bioactive peptides with promising clinical value that may lead to the discovery and development of new drugs. The present study was designed to evaluate the in vitro antimicrobial activities of the venoms extracted from three medically important Saudi scorpions (Androctonus crassicauda, Androctonus bicolor and Leiurus quinquestriatus). Antimicrobial assays were performed using a microplate growth inhibition assay against 10 multidrug-resistant (MDR) micro-organisms (4 Gram-negative bacteria, 2 Gram-positive bacteria and 4 fungi and yeasts) at concentrations ranging from 0 to 20mg/mL of each venom. Following qualitative analysis, dose-response assays were performed for bacterial and fungal killing curves using the MTT colorimetric assay. Among the three tested scorpion venoms, only L. quinquestriatus venom showed significant broad-spectrum antimicrobial activity in a dose-dependent manner from 5 to 20mg/mL. Leiurus quinquestriatus venom inhibited the growth and survival of MDR Escherichia coli (55.2%), Acinetobacter baumannii (50.6%), Klebsiella pneumoniae (35.1%), Pseudomonas aeruginosa (31.3%), Staphylococcus aureus (36.4%), Enterococcus faecalis (47.6%), Candida albicans (31.2%) and Candida glabrata (39.0%), whereas no significant activity against Fusarium oxysporum and Aspergillus flavus was observed. In contrast, the venoms of A. crassicauda and A. bicolor did not show noticeable antimicrobial activity against any of the tested organisms. The findings of the current study demonstrate that L. quinquestriatus venom possesses antimicrobial activity and thus can be used as a template for designing and development of novel antimicrobial drugs.

American Journal of Infection Control, Oct 1, 2012

This study describes and analyzes Acinetobacter baumannii antibiotic susceptibly profile in Alepp... more This study describes and analyzes Acinetobacter baumannii antibiotic susceptibly profile in Aleppo, Syria, thus providing vital information for guiding treatment of A baumannii infections. Two hundred sixty nonrepetitive A baumannii isolates were studied over 3.5 years. Resistance rates are at the higher end of globally reported levels. Newer cephalosporins and β-lactamase-resistant agents are becoming practically ineffective. Better activity is limited to carbapenems and colistin, which elicited the highest susceptibility levels.

This article cites 46 articles, 22 of which can be accessed free

Introduction: The use of mobile phones inside hospitals is a subject of controversy because it ma... more Introduction: The use of mobile phones inside hospitals is a subject of controversy because it may improve the quality of healthcare but also can transmit health care associated infections. Methodology: A cross-sectional study was conducted to screen a total of 426 mobile phones including (274) used by patients, companions, visitors and (152) used by health care workers for microbial pathogens which serve as a reservoir for hospital acquired infections (HAIs) and to assess the effectiveness of simple cleaning with clinical wipes impregnated with 70% isopropyl alcohol for decontamination at a tertiary hospital in Saudi Arabia. Results: Significantly higher rates of pathogens that might be associated with HAIs were found in mobile phones of patients' groups (n=258) versus the health care workers' (n=106) (97.2% vs 71.1% respectively; p≤0.009). Mobile phones owned by patients accounted for the highest rate of isolates (211; 29.3%) followed by companions (150; 20.9%), visitors (...

Journal of global antimicrobial resistance, 2017

Pharmacognosy Communications, 2017

Mobile Genetic Elements, 2013

American Journal of Infection Control, 2012

Multidrug resistance in Pseudomonas aeruginosa isolated from nosocomial respiratory and urinary i... more Multidrug resistance in Pseudomonas aeruginosa isolated from nosocomial respiratory and urinary infections in Aleppo, Syria

Introduction: Antibiotic resistance is a problem of deep scientific concern both in hospital and ... more Introduction: Antibiotic resistance is a problem of deep scientific concern both in hospital and community Settings. The patient environment in healthcare settings has continually proven to harbor a reservoir of potentially harmful, and even lethal multidrug-resistant organisms (MDRO). Methodology: A cross sectional study was carried out to investigate the prevalence of multidrug resistant producing pathogens contaminated mobile phones (MPs) used by patient, companions, visitors and Heath. Results: Out of 426 mobile phones enrolled, a total of 163 isolates linked to hospital acquired infection were recovered. This study revealed high prevalence of multidrugresistant isolates reaching (71.8%), whereas Extended-spectrum betalactamases (ESBLs) producing K. pneumoniae, E. coli and MRSA accounted (27.6%) of the isolates. E. cloacae (88.9%) and S. aureus (85.7%) were found to be the principle MDRO. Likewise 76% of A. baumannii, K. pneumonia and E. coli were MDRO. High prevalence rate of r...

Journal of Biological Chemistry, 2008

Mycobacteria contain an outer membrane composed of mycolic acids and a large variety of other lip... more Mycobacteria contain an outer membrane composed of mycolic acids and a large variety of other lipids. Its protective function is an essential virulence factor of Mycobacterium tuberculosis. Only OmpA, which has numerous homologs in Gram-negative bacteria, is known to form channels in the outer membrane of M. tuberculosis so far. Rv1698 was predicted to be an outer membrane protein of unknown function. Expression of rv1698 restored the sensitivity to ampicillin and chloramphenicol of a Mycobacterium smegmatis mutant lacking the main porin MspA. Uptake experiments showed that Rv1698 partially complemented the permeability defect of the M. smegmatis porin mutant for glucose. These results indicated that Rv1698 provides an unspecific pore that can partially substitute for MspA. Lipid bilayer experiments demonstrated that purified Rv1698 is an integral membrane protein that indeed produces channels. The main single channel conductance is 4.5 ؎ 0.3 nanosiemens in 1 M KCl. Zero current potential measurements revealed a weak preference for cations. Whole cell digestion of recombinant M. smegmatis with proteinase K showed that Rv1698 is surface-accessible. Taken together, these experiments demonstrated that Rv1698 is a channel protein that is likely involved in transport processes across the outer membrane of M. tuberculosis. Rv1698 has single homologs of unknown functions in Corynebacterineae and thus represents the first member of a new class of channel proteins specific for mycolic acidcontaining outer membranes.

These include: This article cites 74 articles, 37 of which can be accessed free at:

The Journal of Infection in Developing Countries

Introduction: Pseudomonas aeruginosa represents a serious clinical challenge due to its frequent ... more Introduction: Pseudomonas aeruginosa represents a serious clinical challenge due to its frequent involvement in nosocomial infections and its tendency towards multidrug resistance. Methodology: This study uncovered antibiotic susceptibility patterns in 177 isolates from inpatients in three key hospitals in Aleppo, the largest city in Syria. Results: Exceptionally low susceptibility to most routinely used antibiotics was uncovered; resistance to ciprofloxacin and gentamicin was 64.9% and 70.3%, respectively. Contrarily, susceptibility to colistin was the highest (89.1%). Conclusions: Multidrug resistance was rife, found at a rate of 53.67% among studied P. aeruginosa isolates.

Background: Recently, there has been a notable surge in urinary tract infections (UTIs) by extend... more Background: Recently, there has been a notable surge in urinary tract infections (UTIs) by extended spectrum b-lactamase (ESBL)-producing Escherichia coli, which considerably limits treatment options. This study aimed to determine prevalence, phenotypic patterns, and ESBL-production status of E coli in isolates from UTI patients along with uncovering locally relevant risk factors for contracting ESBL-producing E coli infections. Methods: One hundred four nonrepetitive urine samples were collected from 3 major hospitals in Aleppo, Syria. Antibiotic susceptibility and ESBL production were studied by disc diffusion and double disk synergy tests according to Clinical Laboratory Standards Institute guidelines. Epidemiologic analysis was done using c 2 and multivariate logistic regression tests. Results: This study revealed high prevalence of multidrug-resistant (MDR) E coli reaching 63%, whereas ESBL-producing E coli exceeded 52%. The latter exhibited alarmingly elevated levels of coresistance to non-b-lactam antibiotics leading to vast increase in MDR rates in comparison with non-ESBL-producing E coli (83.6% vs 12.2%, respectively). Conclusion: We found previous exposure to third-generation cephalosporins and fluoroquinolones to be a significant risk factor for ESBL-producing E coli infections, in addition to other known factors such as hospitalization and catheterization. Tigecycline and carbapenems demonstrated near perfect efficacy against tested E coli, so they rank high among treatment options.

Pharmacognosy Communications, 2017

Journal of Biological Chemistry, Mar 1, 2006

Journal of Bacteriology, Mar 15, 2007

Archives of Ecotoxicology, Mar 31, 2021

Journal of global antimicrobial resistance, Sep 1, 2017

American Journal of Infection Control, Oct 1, 2012

This article cites 46 articles, 22 of which can be accessed free

Journal of global antimicrobial resistance, 2017

Pharmacognosy Communications, 2017

Mobile Genetic Elements, 2013

American Journal of Infection Control, 2012

Journal of Biological Chemistry, 2008

These include: This article cites 74 articles, 37 of which can be accessed free at:

The Journal of Infection in Developing Countries