Study of the antibacterial effects of the starch-based zinc oxide nanoparticles on methicillin resistance Staphylococcus aureus isolates from different clinical specimens of patients from Basrah, Iraq.

This study aimed to assess the efficacy of starch-based zinc oxide nanoparticles (ZnO-NPs) against methicillin-resistant Staphylococcus aureus (MRSA) isolates from clinical specimens in Basrah, Iraq. In this cross-sectional study, 61 MRSA were collected from different clinical specimens of patients in Basrah city, Iraq. MRSA isolates were identified using standard microbiology tests, cefoxitin disc diffusion and oxacillin salt agar. ZnO-NPs were synthesized in three different concentrations (0.1 M, 0.05 M, 0.02 M) by the chemical method using starch as the stabilizer. Starch-based ZnO-NPs were characterized using ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). The antibacterial effects of particles were investigated by the disc diffusion method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the most effective starch-based ZnO-NPs were determined using a broth microdilution assay. The UV-Vis of all concentrations of starch-based ZnO-NPs exhibited a strong absorption band at 360 nm which was characteristic of the ZnO-NPs. XRD assay confirmed the representative hexagonal wurtzite phase of the starch-based ZnO-NPs, and their purity and high crystallinity. The spherical shape with a diameter of 21.56 ± 3.42 and 22.87 ± 3.91 was revealed for the particles by FE-SEM and TEM, respectively. EDS analysis confirmed the presence of zinc (Zn) (61.4 ± 0.54%) and oxygen (O) (36 ± 0.14%). The 0.1 M concentration had the highest antibacterial effects (mean ± SD of inhibition zone = 17.62 ± 2.65 mm) followed by the 0.05 M concentration (16.03 ± 2.24 mm) and the 0.02 M concentration (12.7 ± 2.57 mm). The MIC and the MBC of the 0.1 M concentration were in the range of 25-50 µg/mL and 50-100 µg/mL, respectively. Infections caused by MRSA can be treated with biopolymer-based ZnO-NPs as effective antimicrobials.

Evaluation of the phytoconstituents of Auricularia auricula-judae mushroom and antimicrobial activity of its protein extract.

INTRODUCTION: The growing resistance to antibiotics and the complexity of defeating multi-drug resistant bacteria have led to an increase in the search for novel and effective antimicrobials from various plants. This study aimed to determine the bioactive contents of Auricularia auricular-judae mushroom and evaluate the antimicrobial potential of its protein extract against some selected human bacterial and fungal pathogens which could serve as a lead to the discovery of new antimicrobial agents. METHODS: The constituents of the A. auricular-judae were evaluated by standard phytochemical analysis methods. The agar well diffusion, micro-broth dilution, and time-kill kinetic assays were used to determine the antimicrobial activity of the extracts against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, yeast (Candida albicans), and dermatophytic pathogens. RESULTS: The preliminary phytochemical analysis of the extracts revealed the presence of carbohydrate (43.15 %; 38.30 %) proteins (23.75 %; 23.75 %), flavonoids (1.20 %; 0.80 %), alkaloids (0.60 %; 1.00 %), saponin (6.00 %; 2.40 %), tannin (1.65 %; 1.57 %), cyanide (0.24 %; 0.40 %), ash (12.40 %; 10.40 %), moisture (6.00 %;6.00 %), lipids(6.00 %;6.00 %), and fiber (8.70 %; 6.45 %) for the Tris buffer and warm aqueous extracts, respectively. The Tris and warm aqueous protein extracts showed antimicrobial effects toward all the human bacterial pathogens and two fungal isolates. CONCLUSIONS: This study revealed the potential ability of A. auricula-judae for use as a herbal antimicrobial in the treatment of human bacterial and fungal pathogens.

Preliminary survey of extended-spectrum ß-lactamases (ESBLs) in nosocomial uropathogen Klebsiella pneumoniae in north-central Iran.

Infections caused by extended-spectrum ß-lactamases (ESBLs) producing bacteria, including Klebsiella pneumoniae have increasingly subjected to therapeutic limitations and patients with these infections are at high risk for treatment failure, long hospital stays, high health care costs, and high mortality. The aim of this study was to screen the prevalence of the bla TEM,bla CTX-M and bla SHV ESBL genes in K. pneumoniae strains isolated from nosocomial urinary tract infections (UTIs). During the March 2016 to December 2017, one hundred isolates of K. pneumoniae were collected from urine specimens of patients suffering from nosocomial UTI referred to Khatam Al-Anbia hospital in Shahrud, north-central Iran. All isolates were identified by standard bacteriological tests. The pattern of antibiotic susceptibility was determined according to the CLSI guidelines. The presence of the ESBLs was investigated using the double-disc synergy test (DDST). Polymerase chain reaction technique was used to detect the bla TEM, bla CTX-M and bla SHV genes in DDST positive isolates. Most isolates showed remarkable resistance to tested antibiotics with highest rate against nitrofurantoin (75%) and trimethoprim/sulfamethoxazole (65%). The imipenem was the most effective antibiotic against K. pneumoniae isolates. ESBL phenotype was detected in 50 (50%) of isolates. The prevalence of bla TEM, bla CTX-M and bla SHV genes among 50 ESBLs-positive isolates was 25 (50%), 15 (30%) and 35 (70%) respectively. The bla TEM and bla SHV genes were seen in 25 isolates (50%) simultaneously. The findings of this study indicated the 50% frequency rate of ESBL-producing K. pneumoniae in our geographic region. Since the treatment of infections caused by this bacterium is associated with many limitations, this high prevalence is a warning sign to adopt new control policies to prevent further spread of this microorganism.