Papers by Mahmoud Abd El-Baky
Ureteral catheters are indispensable devices used in the management of ureteral obstruction. Alth... more Ureteral catheters are indispensable devices used in the management of ureteral obstruction. Although the stent is essential for treatment, it also has complications, which are encrustation, stone formation and biofilm formation. Biofilm infections result in a complication in the course of treatment, increasing the length of patients stay in hospital and overall cost. Catheter-associated infections are difficult to be treated with antibiotics and there is a need to change catheters due to the formation of biofilm on their surfaces. In this study, In this study, we examine the effect of some of prescribed drugs as NSAIDs and N-acetylcysteine on the adherence of S. aureus, K. pneumoniae, P. aeruginosa and Proteus mirabilis on the surface of catheters, and their effects on the preformed mature biofims. Also, we determine their antibacterial activity. The results showed that the tested agents had good antibacterial activity, a significant effect on the inhibition of adherence of the tested strains to plastic surfaces and a high disruptive effect on mature biofilms. In conclusion, the tested drugs can be used in the treatment of catheter-associated infections.
Candida spp. are the most common cause of fungal diseases and the fourth commonest cause of nosoc... more Candida spp. are the most common cause of fungal diseases and the fourth commonest cause of nosocomial invasive infections which are considered in many cases as life threatening. Among Candida spp., C. albicans is the most common cause of many fungal diseases, but non-albicans spp. infections are in increase. Non-steroidal anti-inflammatory drugs have previously been shown to have antifungal activity. In this study we determine the antifungal activity of the tested NSAIDs using agar well diffusion method, their effect on the dimorphic transition of C. albicans by testing their ability to form germ tube in the presence of human serum. Determining the effect of NSAIDs on the adherence to plastic surfaces and on the mature biofilms formed by the tested Candida spp.. The results indicated that Sodium Diclofenac showed lower MIC against C. albicans and C. glabrata while Ibuprofen had lower MIC against C. krusei. upon examining the effect of Diclofenac sodium, Ibuprofen and ketoprofen on biofilm formed on polyurethane segments by Scanning electron microscope (SEM), a damage to membranes of the tested species was observed. Sodium Diclofenac showed the highest inhibitory effect on the adherence (51.1-76.9% at MIC and 56.6-83.3% at 2XMIC) of C. albicans and C. glabrata but Ibuprofen showed a higher inhibitory effect against the adherence of C. krusei. For mature biofilms, the highest disruptive effect on mature biofilms formed by all tested Candida Spp. (37.72-59.29% at MIC and 42.68-63.06% at 2XMIC) was observed by Diclofenac sodium. Sodium Diclofenac inhibited dimorphic transition of C. albicans but a decrease in germ tube formation was shown by others. In conclusion, the tested drugs showed antifungal, anti-adherent and anti-biofilm activity that make them useful in the treatment of fungal infection and the prevention of biofilm formation on the surface of medical devices.
N-acetylcysteine (NAC) is used in the treatment of chronic bronchitis that attributed to its mucu... more N-acetylcysteine (NAC) is used in the treatment of chronic bronchitis that attributed to its mucus dissolving properties. Its ability to reduce biofilm formed by different types of bacteria was proven previously in many studies. Therefore we examined its effect on C. albicans biofilms by testing its effect alone and in combination with ketoconazole using Tissue culture plate assay method (TCP). NAC effects on C. albicans morphology and the texture of biofilms were determined using Scanning electron microscope (SEM). It was found that the inhibitory effect of NAC was concentration dependent. NAC reduced C. albicans adherence by ≥32.8% while ketoconazole reduced adherence by ≥25% in comparison to control. Also, it showed higher disruptive effect (50-95%) than ketoconazole (22-80.7%) on mature biofilms. Using NAC and ketoconazole in combination, a significant inhibitory effect (P<0.01) on both adherence and mature biofilms (54-100%) was seen. NAC reduced the amount of biofilm mass in all tested Candida in concentrations at which their growth was not affected. NAC and ketoconazole combinations showed complete eradication to mature biofilms formed in most of the tested strains. NAC can inhibit C. albicans growth, inhibit dimorphism, which is an important step in biofilm formation, and change the texture of the formed biofilms, what makes NAC an interesting agent to be used as an inhibitor for biofilm formation by C. albicans.
The Journal of Infection in Developing Countries, 2009
Background: Staphylococci are a common cause of catheter-associated urinary tract infections. The... more Background: Staphylococci are a common cause of catheter-associated urinary tract infections. The present study evaluated biofilm forming capacity and the presence of both icaA and icaD genes among staphylococci strains isolated from patients undergoing ureteral catheterization. Methodology: Different bacterial strains were isolated from urine and stents segments collected from 100 patients. Strains were identified by traditional microbiological methods. Stents were examined for biofilm using a scanning electron microscope (SEM). Staphylococcal isolates were tested for their ability to produce biofilm using the tissue culture plate assay method (TCP). The presence of icaA and icaD genes was determined by PCR technique. Results: Fifty-three staphylococcal strains were isolated and identified from 284 samples (18.7%). Forty-six staphylococcal strains were isolated from stent segment cultures while only seven strains were isolated from urine samples at the day of stent removal. S. aureus represented 6.3%, and S. epidermidis represented 12.3%. Out of the 18 S. aureus strains, 15 (83.3%) were biofilm producers and out of 35 S. epidermidis strains, 31 (88.6%) were biofilm producers. Staphylococcal strains were further classified as high (56.6%), moderate (30.2%) and non biofilm producers (13.2%). All biofilm producing strains were positive for icaA and icaD genes, and all biofilm negative strains were negative for both genes. Conclusion: Staphylococci isolated from catheter segments showed a higher extent of biofilm production than that isolated from urine samples. All biofilm producing staphylococci were positive for icaA and icaD genes, which indicates the important role of ica genes as virulence markers in staphylococcal infections associated with urinary catheterization.
Aims: Emergence of vancomycin resistant Staphylococcus aureus (VRSA) has been of great concern in... more Aims: Emergence of vancomycin resistant Staphylococcus aureus (VRSA) has been of great concern in clinical settings. Our study aimed to detect vancomycin resistance and the possibility of its conjugal transfer among clinical isolates of S. aureus. Study Design: Medical microbiology. Place and Duration of Study: This study was carried out in the department of microbiology, Faculty of pharmacy, between October 2011 and January 2013. Methodology: Two hundreds and seven samples were collected from different types of infections and examined for Staphylococcus aureus using standard bacteriological procedures, Antimicrobial susceptibility testing against vancomycin and some antimicrobials was done by agar dilution method, resistance to methicillin was determined by disc diffusion test using cefoxitin (30µg), Vancomycin resistance gene transfer was tested by broth matting procedure and confirmed by plasmid and DNA product analysis. Results: Sixty-three samples were positive for Staphylococcus aureus. All isolates were resistant to penicillin while the lowest resistance was to amikacin and vancomycin. One isolate was VRSA (MIC ≥ 16 µg/ml and positive for vanA gene 1032bp) while 5 isolates
Objectives: to study prevalence of ESBLs, AmpC beta lactamase and metallo beta lactamase among cl... more Objectives: to study prevalence of ESBLs, AmpC beta lactamase and metallo beta lactamase among clinical isolates of P. aeruginosa.
Objectives: To evaluate the in vitro antibacterial effect of three different restorative material... more Objectives: To evaluate the in vitro antibacterial effect of three different restorative materials (Glass Ionomer Cements (GIC)) containing chlorohexidine on Streptococcus mutans, and lactobacillus acidophilus.
Objectives: To evaluate the antibacterial activity of the total extracts, methanolic and water ex... more Objectives: To evaluate the antibacterial activity of the total extracts, methanolic and water extract of leaves with stems and the pods of Ceratonia siliqua L. each alone and in combination with some antimicrobials on some pathogens. As the wide use of antibiotics in the treatment of bacterial infections has led to the emergence and spread of resistant strains. Many studies showed that the efficacy of antimicrobials can be improved by combining them with crude plant extracts.
The effect of levofloxacin (LEV) and vitamin-C (VIT-C) individually or in combinations on initial... more The effect of levofloxacin (LEV) and vitamin-C (VIT-C) individually or in combinations on initial bacterial adherence and pre-formed (mature) biofilms on the surface of urethral catheters was studied. The isolated and studied uropathogens in the present study showed considerable diversity, where the major pathogens were identified as E.coli, Klebsiella sp., Citrobacter sp., Enterobacter sp., Proteus sp. and Pseudomonas sp. Using the static adherence assay, addition of LEV and VIT-C each alone at sub MIC concentrations (0.25 MIC and 0.5 MIC) and (80 and 100 mg ml-1) respectively, reduced the initial adherence ability of bacteria to the catheter by 35-94%. Besides, the inhibitory effect on the mature biofilm was estimated to be 40-90% in the presence of (MIC and 2MIC) LEV or (80 and 100 mg/ml) VIT-C. The highest inhibitory effects on both the initial adherence and mature biofilm were recorded when 0.5 MIC levofloxacin was added. Combination of LEV and VIT-C significantly increased the inhibitory effect of both initial biofilm formation and the mature biofilm to 80-100%. In addition, scanning electron microscope (SEM) was used to verify the effect of the tested drugs on biofilm production. The obtained results confirmed the significant role of this combination in inhibition of urethral catheter biofilm formation.
Background: Staphylococci are a common cause of catheter-associated urinary tract infections. The... more Background: Staphylococci are a common cause of catheter-associated urinary tract infections. The present study evaluated biofilm forming capacity and the presence of both icaA and icaD genes among staphylococci strains isolated from patients undergoing ureteral catheterization. Methodology: Different bacterial strains were isolated from urine and stents segments collected from 100 patients. Strains were identified by traditional microbiological methods. Stents were examined for biofilm using a scanning electron microscope (SEM). Staphylococcal isolates were tested for their ability to produce biofilm using the tissue culture plate assay method (TCP). The presence of icaA and icaD genes was determined by PCR technique. Results: Fifty-three staphylococcal strains were isolated and identified from 284 samples (18.7%). Forty-six staphylococcal strains were isolated from stent segment cultures while only seven strains were isolated from urine samples at the day of stent removal. S. aureus represented 6.3%, and S. epidermidis represented 12.3%. Out of the 18 S. aureus strains, 15 (83.3%) were biofilm producers and out of 35 S. epidermidis strains, 31 (88.6%) were biofilm producers. Staphylococcal strains were further classified as high (56.6%), moderate (30.2%) and non biofilm producers (13.2%). All biofilm producing strains were positive for icaA and icaD genes, and all biofilm negative strains were negative for both genes. Conclusion: Staphylococci isolated from catheter segments showed a higher extent of biofilm production than that isolated from urine samples. All biofilm producing staphylococci were positive for icaA and icaD genes, which indicates the important role of ica genes as virulence markers in staphylococcal infections associated with urinary catheterization.
Background: Ureteral catheters are valuable indispensable devices may readily acquire biofilms on... more Background: Ureteral catheters are valuable indispensable devices may readily acquire biofilms on the inner or outer surfaces. This study evaluated the efficacies of ureteral catheters impregnated with ciprofloxacin, N-acetylcysteine each alone and in combination on microbial adherence.
The aim of this study was to evaluate the effect of ciprofloxacin (CIP), N-acetylcysteine (NAC) a... more The aim of this study was to evaluate the effect of ciprofloxacin (CIP), N-acetylcysteine (NAC) alone and in combination on biofilm production and pre-formed mature biofilms on ureteral stent surfaces. Two strains each of Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebseilla pneumoniae, Pseudomonas aeruginosa and Proteus vulgaris, recently isolated from patients undergoing ureteral stent removal and shown to be capable of biofilm production, were used in this study. The inhibitory effects of ciprofloxacin, N-acetylcysteine and ciprofloxacin/N-acetylcysteine combination were determined by static adherence assay. Ciprofloxacin (MIC and 2 MIC) and N-acetylcysteine (2 and 4 mg/ml) inhibited biofilm production by ≥ 60% in all tested microorganisms. Disruption of pre-formed biofilms of all tested microorganisms was found to be ≥ 78% in the presence of ciprofloxacin (MIC and 2 MIC) and ≥ 62% in the presence of N-acetylcysteine (2 and 4 mg/ml), compared to controls. Ciprofloxacin/N-acetylcysteine showed the highest inhibitory effect on biofilm production (94100%) and the highest disruptive effect on the pre-formed biofilms (86100%) in comparison to controls. N-acetylcysteine was found to increase the therapeutic efficacy of ciprofloxacin by degrading the extracellular polysaccharide matrix of biofilms. These data are statistically significant. The inhibitory effects of ciprofloxacin and N-acetylcysteine on biofilm production were also verified by scanning electron microscope (SEM). In conclusion, Ciprofloxacin/N-acetylcysteine combinations have the highest inhibitory effect on biofilm production and the highest ability to eradicate pre-formed mature biofilms. K e y w o r d s: Biofilm, ciprofloxacin, mature biofilm, N-acetylcysteine
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Papers by Mahmoud Abd El-Baky