Molecular characterization of mycotoxin-producing Aspergillus parasiticus and sensitivity pattern to different disinfectants

Aims@#The study was aimed to isolate and characterize the mycotoxin-producing filamentous Aspergillus parasiticus from the feed samples. The sensitivity pattern of the isolates was assessed against different disinfectants.@*Methodology and results@#Fifty different feed samples were screened for A. parasiticus isolation. Isolates were subjected to macroscopic and microscopic characterization. Polymerase chain reaction was performed to confirm the isolates at the genomic level. Mycotoxin producing potential of the isolates was assessed by thin-layer chromatography (TLC). To quantify the toxins, high performance liquid (HPLC) was employed. The antifungal potential of disinfectants was determined by the well diffusion method followed by minimum inhibitory concentration (MIC) calculation. Out of twenty isolates of A. parasiticus, 11(55%) isolates were observed positive for toxin production. Three toxigenic isolates (AspP2, AspP4 and AspP8) were selected to evaluate their susceptibility against disinfectants by well diffusion method. AspP2 produced maximum (5.90 ng/mL) toxin, followed by AspP4 (3.11 ng/mL) and AspP8 (18.47 ng/mL). Terralin showed maximum fungicidal activity with 29.66 ± 8.08 mm zone of inhibition at 0.42 μg/mL MIC. Hypochlorite and Instru Star showed 99% disinfection with 30, 60 and 90 min contact time (6 mean log reduction) for all A. parasiticus isolates. Alpha Guard inhibited growth after 15 min contact time for all the isolates.@*Conclusion, significance and impact of study@#This study provides data indicating the contamination of feed samples with mycotoxin-producing A. parasiticus isolates and their sensitivity against commercially available disinfectants. Use of these disinfectants in appropriate concentrations and time could help prevent the contamination of food, feed and healthcare settings with the fungal species.

Antibacterial potential of indigenous medicinal plants against methicillin-resistant Staphylococcus aureus isolated from septic wounds

Aims@#This study was aimed to screen indigenous medicinal plants for their antibacterial potential against methicillin-resistant Staphylococcus aureus (MRSA).@*Methodology and results@#Three indigenous plants (Nigella sativa, Zingiber officinale and Calotropis procera) and thymoquinone were screened for antibacterial activity against MRSA, isolated from septic wounds of patients admitted to Mayo Hospital Lahore, Pakistan. Isolated bacteria were screened for methicillin and cefoxitin resistance by the Kirby-Bauer method, followed by mecA gene-specific polymerase chain reaction (PCR). Confirmed MRSA was processed for antibacterial activity of plant extracts and thymoquinone followed by cytotoxicity assay of plant extract having least minimum inhibitory concentration (MIC) value. Out of total samples (n=100), S. aureus (29%), MRSA (26%) and vancomycin-resistant S. aureus (VRSA) (21.7%) isolates were recovered based on morphology, biochemical profile and antibiotic susceptibility testing. Nigella sativa showed the highest antibacterial activity (10.06 ± 6.53 mm) against MRSA followed by Z. officinale (4.06 ± 3.72 mm) and C. procera (3.65 ± 3.33 mm) in comparison to standard thymoquinone (17.93 ± 10.14 mm). The least MIC value recorded was for Z. officinale at 36.89 ± 3.75 μg/mL. Zingiber officinale was the most effective antibacterial agent, followed by N. sativa and C. procera and non-toxic for eukaryotic cells at all tested concentrations (1500 μg/mL to 2.92 μg/mL).@*Conclusion, significance and impact of study@#It was concluded that Z. officinale may be used as an effective alternative for treating septic wound infection in local or topical preparations. As pathogenic S. aureus is becoming life-threatening among antibiotic-resistant bacteria and traditional plants are in used for centuries to treat septic wound infections.

Biofuel production potential of indigenous isolates of Scenedesmus sp. from lake water in Pakistan

Aims@#This paper presents the report on biodiesel and biogas production at a laboratory scale from Scenedesmus strain.@*Methodology and results@#Previously isolated and identified Scenedesmus were grown in 10 Liter flask using BG-11 media at 16 h light and 8 h dark cycle. Oven-dried biomass (20 g) from 16-day-old culture of Scenedesmus was finely grounded and subjected to lipids extraction by chloroform-methanol-NaCl mixture. Microalgal lipids (6 mL) were subjected to transesterification by using NaOH leading to the production of 5 mL biodiesel and 4 mL of glycerin. Biodiesel was rich in methyl esters of linoleic acid, phosphorothioc acid and dodecanoic acid, as shown by gas chromatography-mass spectrometry (GC-MS) analysis. Oven-dried microalgae (2 g) without lipid extraction and leftover biomass (2 g) after lipid extraction were subject to biogas production through anaerobic digestion. Biogas (34, 27 and 19 mL) were recorded respectively in oven-dried whole biomass; lipid extracted biomass and control over a period of 15 days of anaerobic digestion.@*Conclusion, significance and impact of study@#It was concluded that water bodies are rich in diverse algae, especially Scenedesmus sp., and this algae can be cultured to produce biodiesel and biogas. But the lipid accumulation potential of microalgae requires special treatment and lipid extraction methods are not up to the mark, which is a major bottleneck in biofuel production from microalgae.

Evaluation of cytotoxicity and antiviral activity of ivermectin against newcastle disease virus

Cytotoxic and antiviral potential of ivermectin and ribavirin was evaluated. Cytotoxicity was checked on chick primary fibroblast cell line through MTT assay. Antiviral potential was determined against Newcastle disease virus on 9- day old chicken embryos. Six different concentrations [200, 100, 50, 25, 12.5 and 6.25[micro]g/mL] of both the drugs were evaluated. The 100[micro]g/mL concentration of ivermectin and higher were cytotoxic. The 25[micro]g/mL concentration of ribavirin and higher were cytotoxic. Comparison of ivermectin and ribavirin showed that ivermectin was safe at 50[micro]g/mL and lower concentrations. Ribavirin was protective for cell at 12.5[micro]g/mL and 6.25[micro]g/mL only. Comparison of antiviral activity indicated that ivermectin has strong antiviral potential at 100[micro]g/mL and higher but same concentrations were cytotoxic. Ribavirin showed strong antiviral potential at all concentrations

Preparation and in vitro evaluation of Nystatin micro emulsion based gel

Nystatin is a polyene antimycotic obtained from Streptomyces noursei used in the treatment of topical and transdermal fungal infection. Nystatin is nearly insoluble in water [<0.1] and it is amphoteric in nature. The aim of the present study was to design and develop Nystatin micro emulsion based gel for efficient delivery of drug to the skin by water titration method. The Pseudoternary phase diagrams 1:2, 1:1 and 2:1 were constructed by water titration method. Micro emulsion based gel was prepared by using oleic acid, Tween 20, propylene glycol as an oil phase, surfactant and cosurfactant respectively. Cabopol 940 was used as a gelling agent. In vitro evaluation of micro emulsion based gel was done for pH, Viscosity, spreadability and droplet size. Micro emulsion based gel showed greater antifungal activity against Candida albicansas compared to control formulations. In vitro drug release studies were conducted for micro emulsion based gel and control formulation using Franz diffusion cell. Drug penetration through synthetic skin followed Zero order model as the values for R[2] higher in case of zero order equation. The optimized micro emulsion based gel was found to be stable and showed no physical changes when exposed to different temperatures for a period of 4 week. The results indicated that the micro emulsion based gel system studied would be a promising tool for enhancing the percutaneous delivery of Nystatin

Isolation and antibiotic susceptibility of E. coli from urinary tract infections in a tertiary care hospital

The study was conducted to isolate and determine the antibiotic resistance in E. coli from urinary tract infections in a tertiary care hospital, Lahore. Urine samples [n=500] were collected from patients with signs and symptoms of Urinary tract infections. Bacteria were isolated and identified by conventional biochemical profile. Antibiotic resistance pattern of E. coli against different antibiotic was determined by Kirby-Baur method. Bacterial etiological agent was isolated from 402 samples with highest prevalence of E. coli [321, 80%] followed by Staphylococcus aureus [9.4%], Proteus species [5.4%] and Pseudomonas species [5.2%]. The E. coli were highly resistant to penicillin [100%], amoxicillin [100%] and cefotaxime [89.7%], followed by intermediate level of resistance to ceftazidime [73.8%], cephradine [73.8%], tetracycline [69.4%], doxycycline [66.6%], augmentin [62.6%], gentamycin [59.8%], cefuroxime [58.2%], ciprofloxacin [54.2%], cefaclor [50%], aztreonam [44.8%], ceftriaxone [43.3%], imipenem [43.3%], and low level of resistance to streptomycin [30%], kanamycin [19.9%], tazocin [14%], amikacin [12.7%] and lowest to norfloxacin [11.2%]. Out of 321 E. coli isolates, 261 [81%] were declared as multiple drug resistant and 5 [1.5%] were extensive drug resistant. It is concluded that most of the urinary tract infections in human are caused by multiple drug resistant E. coli