Phenotypic and genotypic detection of antibiotic resistance of Pseudomonas aeruginosa isolated from urinary tract infections

Bakground: Pseudomonas aeruginosa is a major nosocomial uropathogen. It can tolerate a wide variety of physical conditions and many antibiotics by different resistance mechanisms.Objectives: This study aimed to investigate the mechanisms of antibiotics resistance in uropathogenic P. aeruginosa clinical isolates.Methods: Two hundred sixty six urine samples were collected from Zagazig University Hospitals, Zagazig, Egypt. P. aeruginosa isolates were identified using standard microbiological tests. The sensitivity to different antibiotics was determined by disc diffusion method. Anti-microbial resistance mechanisms were investigated using phenotypic methods and confirmed by PCR.Results: Fifty P. aeruginosa isolates were recovered. All isolates were MDR and were resistant to amoxicillin/clavulinic, sulphamethaxzole/trimethoprim, doxycycline and ceftazidime. Phenotypic detection of resistance mechanisms revealed that all strains have efflux mechanism, outer membrane porins, and AmpC β-lactamase; none of the strains showed ESBL activity and two of the imipenem resistant strains showed MβL activity. PCR analysis showed that all strains have MexAB-R, OprD and AmpC genes, 42 strains had PSE gene, while VEB and VIM genes were not detected.Conclusion: The resistance rates in P. aeruginosa were higher than global values; this resistance was attributed to several mechanisms. This high resistance is alarming and necessitates applying strict antibiotic prescription policies.Keywords: Pseudomonas aeruginosa, urinary tract infections, antibiotic resistance, resistance mechanisms

Relationship between Sap prevalence and biofilm formation among resistant clinical isolates of Candida albicans

Background: Fungal infections represent a serious health problem especially in immunocompromised individuals. Candida albicans is the most common fungi that cause superficial and systemic infections with high mortality rates. Anti-fungal resistance of C. albicans may be attributed to its virulence. Biofilm formation and proteolytic activity are major virulence determents that may influence both pathogenicity and anti-fungal resistance of Candida albicans. Objective: This work studied the relation between biofilm formation, proteolytic activity and prevalence of some Sap genes with reduced susceptibility of C. albicans to different anti-fungal agents. Methods: Fifty three C. albicans strains isolated from patients with systemic infections, identified by germ tube, chromogenic agar and confirmed by PCR, were subjected to evaluate their proteolytic activity, the degree of biofilm production and the prevalence of Sap9 and Sap10 genes. The susceptibility of the isolates was determined by disk diffusion method against five antifungal drugs. Results and conclusion: Four of the C. albicans isolates were resistant to 3 anti-fungal drugs, strong biofilm producer, have proteolytic activity and contain either Sap9 or Sap10 or both. Conclusively, although anti-fungal resistance among the isolates was rare, a relation between the anti-fungal resistance and some major virulence factors was evidently proved in this study

Phenotypic and genotypic detection of antibiotic resistance of Pseudomonas aeruginosa isolated from urinary tract infections

Bakground: Pseudomonas aeruginosa is a major nosocomial uropathogen. It can tolerate a wide variety of physical conditions and many antibiotics by different resistance mechanisms. Objectives: This study aimed to investigate the mechanisms of antibiotics resistance in uropathogenic P. aeruginosa clinical isolates. Methods: Two hundred sixty six urine samples were collected from Zagazig University Hospitals, Zagazig, Egypt. P. aeruginosa isolates were identified using standard microbiological tests. The sensitivity to different antibiotics was determined by disc diffusion method. Anti-microbial resistance mechanisms were investigated using phenotypic methods and confirmed by PCR. Results: Fifty P. aeruginosa isolates were recovered. All isolates were MDR and were resistant to amoxicillin/clavulinic, sulphamethaxzole/trimethoprim, doxycycline and ceftazidime. Phenotypic detection of resistance mechanisms revealed that all strains have efflux mechanism, outer membrane porins, and AmpC \u3b2-lactamase; none of the strains showed ESBL activity and two of the imipenem resistant strains showed M\u3b2L activity. PCR analysis showed that all strains have MexAB-R, OprD and AmpC genes, 42 strains had PSE gene, while VEB and VIM genes were not detected. Conclusion: The resistance rates in P. aeruginosa were higher than global values; this resistance was attributed to several mechanisms. This high resistance is alarming and necessitates applying strict antibiotic prescription policies

Evaluation of polymethyl-methacrylate and acetal denture base resins processed by two different techniques before and after nano-chlorohexidine surface treatment

Abstract Background Flexible denture base polymers have gained popularity in modern dentistry however, their biofilm formation tendency, adversely affecting the oral tissue heath, remains a concern. Consequently, this study aimed to evaluate surface roughness and biofilm formation tendency of two types of denture base resins manufactured with two techniques before and after surface coating with chlorohexidine (CHX) NPs. Materials and methods Acetal (AC) and Polymethyl-methacrylate (PMMA) resins manufactured by conventional and CAD/CAM methods were shaped into disk (10 X 10 X 1 mm). They were dipped for 8 h and 24 h in colloidal suspension prepared by mixing aqueous solution of CHX digluconate and hexa-metaphosphate (0.01 M). Surface roughness, optical density (OD) of microbial growth media and biofilm formation tendency were evaluated directly after coating. Elutes concentrations of released CHX were evaluated for 19 days using spectrophotometer. Three-way ANOVA and Tukey’s post-hoc statistical analysis were used to assess the outcomes. Results AC CAD/CAM groups showed statistically significant higher roughness before and after coating (54.703 ± 4.32 and 77.58 ± 6.07 nm, respectively). All groups showed significant reduction in OD and biofilm formation tendency after surface coating even after 19 days of CHX NPs release. Conclusions Biofilm formation tendency was highly relevant to surface roughness of tested resins before coating. After CHX NPs coating all tested groups showed significant impact on microbial growth and reduction in biofilm formation tendency with no relation to surface roughness. Significant antimicrobial effect remained even after 19 days of NPs release and specimens storage

The Link between Occurrence of Class I Integron and Acquired Aminoglycoside Resistance in Clinical MRSA Isolates

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of nosocomial infections because of its high resistance. Here, we study the antibiotic resistance in MRSA clinical isolates and their relation to integron I occurrence. A total of 88 clinical Staphylococcusaureus isolates were collected. MRSA were identified by the disk diffusion method (DDM) and confirmed by PCR, and antibiogram was determined by DDM. Integron I, II and the aacA4 gene were investigated by PCR. Integrase-positive strains were analyzed for the presence of resistance gene cassettes by sequencing. All isolates were identified as MRSA by DDM and confirmed by PCR. All isolates were resistant to ampicillin and cefoxitin. Concerning aminoglycosides, the frequency of resistance was reported for streptomycin (60.7%), tobramycin (37.1%) gentamicin (36%), and for amikacin (15.9%). Integron I was detected in 41 isolates (46.6%), while integron II was detected in three isolates (3.4%). Sequencing of the integron I-cassette indicated the exclusive prevalence of addA gene variants mediating aminoglycoside resistance. The aacA4 gene was found in DNA of 31 isolates (35.22%). This study revealed the high existence of MRSA. Furthermore, the AacA4 gene and class I integron harboring aadA gene were predominant in MRSA isolates

Cinnamomum zeylanicum bark essential oil induces cell wall remodelling and spindle defects in Candida albicans

Abstract Background Cinnamon (Cinnamomum zeylanicum) bark extract exhibits potent inhibitory activity against Candida albicans but the antifungal mechanisms of this essential oil remain largely unexplored. Results We analyzed the impact of cinnamon bark oil on C. albicans RSY150, and clinical strains isolated from patients with candidemia and candidiasis. The viability of RSY150 was significantly compromised in a dose dependent manner when exposed to cinnamon bark oil, with extensive cell surface remodelling at sub inhibitory levels (62.5 μg/mL). Atomic force microscopy revealed cell surface exfoliation, altered ultrastructure and reduced cell wall integrity for both RSY150 and clinical isolates exposed to cinnamon bark oil. Cell wall damage induced by cinnamon bark oil was confirmed by exposure to stressors and the sensitivity of cell wall mutants involved in cell wall organization, biogenesis, and morphogenesis. The essential oil triggered cell cycle arrest by disrupting beta tubulin distribution, which led to mitotic spindle defects, ultimately compromising the cell membrane and allowing leakage of cellular components. The multiple targets of cinnamon bark oil can be attributed to its components, including cinnamaldehyde (74%), and minor components (< 6%) such as linalool (3.9%), cinamyl acetate (3.8%), α-caryophyllene (5.3%) and limonene (2%). Complete inhibition of the mitotic spindle assembly was observed in C. albicans treated with cinnamaldehyde at MIC (112 μg/mL). Conclusions Since cinnamaldehyde disrupts both the cell wall and tubulin polymerization, it may serve as an effective antifungal, either by chemical modification to improve its specificity and efficacy or in combination with other antifungal drugs

Back to Nature: Combating Candida albicans Biofilm, Phospholipase and Hemolysin Using Plant Essential Oils

Candida albicans is the causative agent of fatal systemic candidiasis. Due to limitations of antifungals, new drugs are needed. The anti-virulence effect of plant essential oils (EOs) was evaluated against clinical C. albicans isolates including cinnamon, clove, jasmine and rosemary oils. Biofilm, phospholipase and hemolysin were assessed phenotypically. EOs were evaluated for their anti-virulence activity using phenotypic methods as well as scanning electron microscopy (SEM) and atomic force microscopy (AFM). Among the C. albicans isolates, biofilm, phospholipase and hemolysins were detected in 40.4, 86.5 and 78.8% of isolates, respectively. Jasmine oil showed the highest anti-biofilm activity followed by cinnamon, clove and rosemary oils. SEM and AFM analysis showed reduced adherence and roughness in the presence of EOs. For phospholipase, rosemary oil was the most inhibitory, followed by jasmine, cinnamon and clove oils, and for hemolysins, cinnamon had the highest inhibition followed by jasmine, rosemary and clove oils. A molecular docking study revealed major EO constituents as promising inhibitors of the Als3 adhesive protein, with the highest binding for eugenol, followed by 1,8-cineole, 2-phenylthiolane and cinnamaldehyde. In conclusion, EOs have a promising inhibitory impact on Candida biofilm, phospholipase and hemolysin production, hence EOs could be used as potential antifungals that impact virulence factors