Antibacterial activity of silver nanoparticles against carbapenem-resistant Acinetobacter baumannii clinical isolates.

Carbapenem-resistant Acinetobacter baumannii (CRAB) produce resistance to various classes of antibiotics and left limited options for treatment. This study was designed to determine antibacterial activity of AgNPs against CRAB. Total 100 A. baumannii were collected from a tertiary care hospital, Lahore. Isolates were subcultured on blood and MacConkey agar. Preliminary identification was carried out by morphological and biochemical tests. Antibiogram was done by Kirby-Bauer disc diffusion method. Antibacterial activity of AgNPs was performed by agar well diffusion method, while minimum inhibitory concentration and minimum bactericidal concentration were determined by micro broth dilution assay. Of 100 A. baumannii, 24 were confirmed as carbapenem-resistant. These isolates were mainly recovered from tracheal secretion (8; 33%), CSF (5; 20.8%), and urine (4; 16.8%). Antibacterial activity of AgNPs revealed a maximum zone of inhibition, 22mm at 50mg/mL and 18mm at 40mg/mL by agar well diffusion method. MIC of AgNPs determined that 14 CRAB were inhibited at 12.5mg/mL and 7 at 25mg/mL. However, MBC revealed that 13 CRAB were killed at 25mg/mL and 7 at 50mg/mL. This study concluded that most of the CRAB were inhibited and killed at 12.5mg/mL and 25mg/mL, respectively. AgNPs can be used as an alternative therapeutic agent followed by their pharmacokinetics and pharmacognosy.

In vitro efficacy of Azadirachta indica leaf extract against methicillin resistant Staphylococci isolated from skin infection.

In this cross-sectional study, the isolation and identification of Methicillin Resistant Staphylococcus aureus (MRSA) and Methicillin Resistant S. epidermidis (MRSE) was described from skin infections (n=100). Initial isolation was done by conventional procedures followed by amplification/ sequence analysis of 16S rRNA. Methicillin resistance was determined using cefoxitin discs and resistant isolates were screened for mec-A gene followed by Minimum Inhibitory Concentrations (MIC) determination of vancomycin. In second phase, we investigated extract of Azadirachta indica leaves using Fourier Transformed Infrared Spectroscopy (FTIR-Spectroscopy) and investigated in vitro activity. Initially, total of 28 Staphylococci were identified. 16S rRNA gene sequence confirmed S. aureus (22), S. epidermidis (3) and S. saprophyticus (3) isolates. Cefoxitin discs showed (7/22) MRSA, (3/3) (MRSE) and none of the methicillin resistant S. saprophyticus. MRSA and MRSE isolates showed presence of mec-A gene. However, all isolates were sensitive to vancomycin MIC (0.5-2µg/mL) and sensitive to Linezolid. FTIR-Spectroscopy of A. indica indicated the presence of azadirachtin and nimbolinin. The mean zone of inhibition was measured 14.23±1.37 and 13.66±0.70 against MRSA and MRSE isolates, respectively. Altogether, MRSA and MRSE is significant public health concern. However, vancomycin and linezolid were found effective and extract of A. indica showed in vitro effects.

Efficacy of Azadirachta indica organic extracts against clinical methicillin resistant Staphylococcus aureus isolates.

In current study we investigated the efficacy of organic extracts of Azadirachta indica leaves against Methicillin Resistant Staphylococcus aureus (MRSA) clinical isolates. For this purpose fresh leaves were used to prepare ethanol, methanol and chloroform extract. Secondly, a cross sectional study was conducted to isolate MRSA in clinical samples from patients having surgical/ non-surgical wounds from Allied Hospital and District Head Quarter Hospital, Faisalabad. The S. aureus isolates were initially identified by biochemical characterization, followed by identification of MRSA using cefoxitin disc diffusion test that was finally confirmed by genomic amplification of mecA gene, responsible for resistance. All MRSA isolates were tested to find vancomycin resistant S. aureus (VRSA) using E-strips (M.I.C. EvaluatorTM, Oxide, UK). The data showed an overall 37% prevalence of S. aureus including 56.75% clinical MRSA isolates while none of the isolated S. aureus showed resistance to vancomycin. The antimicrobial activity was measured as mean zone of inhibition for each extract against all MRSA isolates and it was found as 15.38±2.26, 16.09±3.09 and 17.42±2.48 for methanol, ethanol and chloroform extracts respectively. Chloroform extract showed significantly high antimicrobial activity against MRSA isolates. Altogether, the current study exposed the high prevalence of MRSA isolates from tertiary care hospitals. However, all MRSA isolates were found susceptible to organic extracts of A. indica leaves.

Antimicrobial activity of the bioactive components of essential oils from Pakistani spices against Salmonella and other multi-drug resistant bacteria.

BACKGROUND: The main objective of this study was the phytochemical characterization of four indigenous essential oils obtained from spices and their antibacterial activities against the multidrug resistant clinical and soil isolates prevalent in Pakistan, and ATCC reference strains. METHODS: Chemical composition of essential oils from four Pakistani spices cumin (Cuminum cyminum), cinnamon (Cinnamomum verum), cardamom (Amomum subulatum) and clove (Syzygium aromaticum) were analyzed on GC/MS. Their antibacterial activities were investigated by minimum inhibitory concentration (MIC) and Thin-Layer Chromatography-Bioautographic (TLC-Bioautographic) assays against pathogenic strains Salmonella typhi (D1 Vi-positive), Salmonella typhi (G7 Vi-negative), Salmonella paratyphi A, Escherichia coli (SS1), Staphylococcus aureus, Pseudomonas fluorescens and Bacillus licheniformis (ATCC 14580). The data were statistically analyzed by using Analysis of Variance (ANOVA) and Least Significant Difference (LSD) method to find out significant relationship of essential oils biological activities at p <0.05. RESULTS: Among all the tested essential oils, oil from the bark of C. verum showed best antibacterial activities against all selected bacterial strains in the MIC assay, especially with 2.9 mg/ml concentration against S. typhi G7 Vi-negative and P. fluorescens strains. TLC-bioautography confirmed the presence of biologically active anti-microbial components in all tested essential oils. P. fluorescens was found susceptible to C. verum essential oil while E. coli SS1 and S. aureus were resistant to C. verum and A. subulatum essential oils, respectively, as determined in bioautography assay. The GC/MS analysis revealed that essential oils of C. cyminum, C. verum, A. subulatum, and S. aromaticum contain 17.2% cuminaldehyde, 4.3% t-cinnamaldehyde, 5.2% eucalyptol and 0.73% eugenol, respectively. CONCLUSIONS: Most of the essential oils included in this study possessed good antibacterial activities against selected multi drug resistant clinical and soil bacterial strains. Cinnamaldehyde was identified as the most active antimicrobial component present in the cinnamon essential oil which acted as a strong inhibitory agent in MIC assay against the tested bacteria. The results indicate that essential oils from Pakistani spices can be pursued against multidrug resistant bacteria.