Displaying publications 21 - 36 of 36 in total

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  1. Fulltext Next generation sequencing reveals the antibiotic resistant variants in the genome of Pseudomonas aeruginosa
    Ramanathan B, Jindal HM, Le CF, Gudimella R, Anwar A, Razali R, et al.
    PLoS One, 2017;12(8):e0182524.
    PMID: 28797043 DOI: 10.1371/journal.pone.0182524
    Rapid progress in next generation sequencing and allied computational tools have aided in identification of single nucleotide variants in genomes of several organisms. In the present study, we have investigated single nucleotide polymorphism (SNP) in ten multi-antibiotic resistant Pseudomonas aeruginosa clinical isolates. All the draft genomes were submitted to Rapid Annotations using Subsystems Technology (RAST) web server and the predicted protein sequences were used for comparison. Non-synonymous single nucleotide polymorphism (nsSNP) found in the clinical isolates compared to the reference genome (PAO1), and the comparison of nsSNPs between antibiotic resistant and susceptible clinical isolates revealed insights into the genome variation. These nsSNPs identified in the multi-drug resistant clinical isolates were found to be altering a single amino acid in several antibiotic resistant genes. We found mutations in genes encoding efflux pump systems, cell wall, DNA replication and genes involved in repair mechanism. In addition, nucleotide deletions in the genome and mutations leading to generation of stop codons were also observed in the antibiotic resistant clinical isolates. Next generation sequencing is a powerful tool to compare the whole genomes and analyse the single base pair variations found within the antibiotic resistant genes. We identified specific mutations within antibiotic resistant genes compared to the susceptible strain of the same bacterial species and these findings may provide insights to understand the role of single nucleotide variants in antibiotic resistance.
    Matched MeSH terms: Disk Diffusion Antimicrobial Tests
  2. In vitro activities of 28 antimicrobial agents against methicillin-resistant Staphylococcus aureus (MRSA) from a clinical setting in Malaysia
    Neela V, Sasikumar M, Ghaznavi GR, Zamberi S, Mariana S
    Southeast Asian J Trop Med Public Health, 2008 Sep;39(5):885-92.
    PMID: 19058585
    Methicillin-resistant Staphylococcus aureus (MRSA), an established nosocomial and emerging community pathogen associated with many fatalities due to its hyper-virulence and multiple drug resistant properties, is on the continuous rise. To update the current status on the susceptibility of local MRSA isolates to various classes of antibiotics and to identify the most potent antibiotics, thirty-two clinical isolates comprised of hospital acquired (HA) and community acquired (CA) infections were investigated by disk diffusion test. Of the 32 MRSA isolates, 14 (43.75%) and 18 (56.25%) were community and hospital acquired MRSA, respectively. All isolates were multiple drug resistant to more than 3 classes of antibiotics despite the source or specimen from which it was isolated. The oxacillin MICs for all isolates ranged from 2 to > or = 256 microg/ml. Twenty-five of 26 erythromycin-resistant MRSA isolates exhibited an inducible MLS(B) resistance phenotype while one showed an MS phenotype. More than half the isolates (68.75%) were resistant to at least one of the six aminoglycosides tested, with netilmicin as the most susceptible. The most effective antistaphylococcal agents were linezolid, vancomycin, teicoplanin and quinupristin/dalfopristin exhibited 100% susceptibility. Since MRSA is under continuous pressure of acquiring multiple drug resistance, it is imperative to focus routine surveillance on HA and CA-MRSA strains to monitor and limit the spread of this organism.
    Matched MeSH terms: Disk Diffusion Antimicrobial Tests
  3. An outbreak of Streptococcus agalactiae infection in cage-cultured golden pompano, Trachinotus blochii (Lacépède), in Malaysia
    Amal MN, Zamri-Saad M, Iftikhar AR, Siti-Zahrah A, Aziel S, Fahmi S
    J Fish Dis, 2012 Nov;35(11):849-52.
    PMID: 22913387 DOI: 10.1111/j.1365-2761.2012.01443.x
    Matched MeSH terms: Disk Diffusion Antimicrobial Tests
  4. Fulltext Fabrication of silver nanoparticles doped in the zeolite framework and antibacterial activity
    Shameli K, Ahmad MB, Zargar M, Yunus WM, Ibrahim NA
    Int J Nanomedicine, 2011;6:331-41.
    PMID: 21383858 DOI: 10.2147/IJN.S16964
    Using the chemical reduction method, silver nanoparticles (Ag NPs) were effectively synthesized into the zeolite framework in the absence of any heat treatment. Zeolite, silver nitrate, and sodium borohydride were used as an inorganic solid support, a silver precursor, and a chemical reduction agent, respectively. Silver ions were introduced into the porous zeolite lattice by an ion-exchange path. After the reduction process, Ag NPs formed in the zeolite framework, with a mean diameter of about 2.12-3.11 nm. The most favorable experimental condition for the synthesis of Ag/zeolite nanocomposites (NCs) is described in terms of the initial concentration of AgNO(3). The Ag/zeolite NCs were characterized by ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence, and Fourier transform infrared. The results show that Ag NPs form a spherical shape with uniform homogeneity in the particle size. The antibacterial activity of Ag NPs in zeolites was investigated against Gram-negative bacteria (ie, Escherichia coli and Shigella dysentriae) and Gram-positive bacteria (ie, Staphylococcus aureus and methicillin-resistant Staphylococcus aureus) by disk diffusion method using Mueller-Hinton agar at different sizes of Ag NPs. All of the synthesized Ag/zeolite NCs were found to have antibacterial activity. These results show that Ag NPs in the zeolite framework can be useful in different biological research and biomedical applications.
    Matched MeSH terms: Disk Diffusion Antimicrobial Tests
  5. Fulltext Artocarpus altilis extracts as a food-borne pathogen and oxidation inhibitors: RSM, COSMO RS, and molecular docking approaches
    Ahmad MN, Karim NU, Normaya E, Mat Piah B, Iqbal A, Ku Bulat KH
    Sci Rep, 2020 06 12;10(1):9566.
    PMID: 32533034 DOI: 10.1038/s41598-020-66488-7
    Lipid oxidation and microbial contamination are the major factors contributing to food deterioration. Food additives like antioxidants and antibacterials can prevent food spoilage by delaying oxidation and preventing the growth of bacteria. Artocarpus altilis leaves exhibited biological properties that suggested its use as a new source of natural antioxidant and antimicrobial. Supercritical fluid extraction (SFE) was used to optimize the extraction of bioactive compounds from the leaves using response surface methodology (yield and antioxidant activity). The optimum SFE conditions were 50.5 °C temperature, 3784 psi pressure and 52 min extraction time. Verification test results (Tukey's test) showed that no significant difference between the expected and experimental DPPH activity and yield value (99%) were found. Gas-chromatography -mass spectrometry (GC-MS) analysis revealed three major bioactive compounds existed in A. altilis extract. The extract demonstrated antioxidant and antibacterial properties with 2,3-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, ferric reducing ability of plasma (FRAP), hydroxyl radical scavenging activity, tyrosinase mushrrom inhibition of 41.5%, 8.15 ± 1.31 (µg of ascorbic acid equivalents), 32%, 37% and inhibition zone diameter of 0.766 ± 0.06 cm (B. cereus) and 1.27 ± 0.12 cm (E. coli). Conductor like screening model for real solvents (COSMO RS) was performed to explain the extraction mechanism of the major bioactive compounds during SFE. Molecular electrostatic potential (MEP) shows the probability site of nucleophilic and electrophilic attack during bacterial inhibition. Based on molecular docking study, non-covalent interactions are the main interaction occurring between the major bioactive compounds and bacteria (antibacterial inhibition).
    Matched MeSH terms: Disk Diffusion Antimicrobial Tests
  6. Fulltext In vitro screening of five local medicinal plants for antibacterial activity using disc diffusion method
    Zaidan MR, Noor Rain A, Badrul AR, Adlin A, Norazah A, Zakiah I
    Trop Biomed, 2005 Dec;22(2):165-70.
    PMID: 16883283 MyJurnal
    Medicinal plants have many traditional claims including the treatment of ailments of infectious origin. In the evaluation of traditional claims, scientific research is important. The objective of the study was to determine the presence of antibacterial activity in the crude extracts of some of the commonly used medicinal plants in Malaysia, Andrographis paniculata, Vitex negundo, Morinda citrifolia, Piper sarmentosum, and Centella asiatica. In this preliminary investigation, the leaves were used and the crude extracts were subjected to screening against five strains of bacteria species, Methicillin Resistant Staphylococcus aureus (MRSA), Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa and Escherichia coli, using standard protocol of Disc Diffusion Method (DDM). The antibacterial activities were assessed by the presence or absence of inhibition zones and MIC values. M. citrifolia, P. sarmentosum and C. asiatica methanol extract and A. paniculata (water extract) have potential antibacterial activities to both gram positive S. aureus and Methicillin Resistant S. aureus (MRSA). None of the five plant extracts tested showed antibacterial activities to gram negative E. coli and K. pneumoniae, except for A. paniculata and P. sarmentosum which showed activity towards P. aeruginosa. A. paniculata being the most potent at MIC of 2 g/disc. This finding forms a basis for further studies on screening of local medicinal plant extracts for antibacteria properties.
    Matched MeSH terms: Disk Diffusion Antimicrobial Tests
  7. Preparation and properties of cellulose nanocomposite films with in situ generated copper nanoparticles using Terminalia catappa leaf extract
    Muthulakshmi L, Rajini N, Nellaiah H, Kathiresan T, Jawaid M, Rajulu AV
    Int J Biol Macromol, 2017 Feb;95:1064-1071.
    PMID: 27984140 DOI: 10.1016/j.ijbiomac.2016.09.114
    In the present work, copper nanoparticles (CuNPs) were in situ generated inside cellulose matrix using Terminalia catappa leaf extract as a reducing agent. During this process, some CuNPs were also formed outside the matrix. The CuNPs formed outside the matrix were observed with transmission electron microscope (TEM) and scanning electron microscope (SEM). Majority of the CuNPs formed outside the matrix were in the size range of 21-30nm. The cellulose/CuNP composite films were characterized by Fourier transform infrared spectroscopic, X-Ray diffraction and thermogravimetric techniques. The crystallinity of the cellulose/CuNP composite films was found to be lower than that of the matrix indicating rearrangement of cellulose molecules by in situ generated CuNPs. Further, the expanded diffractogram of the composite films indicated the presence of a mixture of Cu, CuO and Cu2O nanoparticles. The thermal stability of the composites was found to be lower than that of the composites upto 350°C beyond which a reverse trend was observed. This was attributed to the catalytic behaviour of CuNPs for early degradation of the composites. The composite films possessed sufficient tensile strength which can replace polymer packaging films like polyethylene. Further, the cellulose/CuNP composite films exhibited good antibacterial activity against E.coli bacteria.
    Matched MeSH terms: Disk Diffusion Antimicrobial Tests
  8. Fulltext Green synthesis of silver/montmorillonite/chitosan bionanocomposites using the UV irradiation method and evaluation of antibacterial activity
    Shameli K, Ahmad MB, Yunus WM, Rustaiyan A, Ibrahim NA, Zargar M, et al.
    Int J Nanomedicine, 2010 Oct 22;5:875-87.
    PMID: 21116328 DOI: 10.2147/IJN.S13632
    In this study, silver nanoparticles (Ag-NPs) were synthesized using a green physical synthetic route into the lamellar space of montmorillonite (MMT)/chitosan (Cts) utilizing the ultraviolet (UV) irradiation reduction method in the absence of any reducing agent or heat treatment. Cts, MMT, and AgNO(3) were used as the natural polymeric stabilizer, solid support, and silver precursor, respectively. The properties of Ag/MMT/Cts bionanocomposites (BNCs) were studied as the function of UV irradiation times. UV irradiation disintegrated the Ag-NPs into smaller sizes until a relatively stable size and size distribution were achieved. Meanwhile, the crystalline structure and d-spacing of the MMT interlayer, average size and size distribution, surface morphology, elemental signal peaks, functional groups, and surface plasmon resonance of Ag/MMT/Cts BNCs were determined by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence, Fourier transform infrared, and UV-visible spectroscopy. The antibacterial activity of Ag-NPs in MMT/Cts was investigated against Gram-positive bacteria, ie, Staphylococcus aureus and methicillin-resistant S. aureus and Gram-negative bacteria (ie, Escherichia coli) by the disk diffusion method on Muller-Hinton Agar at different sizes of Ag-NPs. All of the synthesized Ag/MMT/Cts BNCs were found to have high antibacterial activity. These results show that Ag/MMT/Cts BNCs can be useful in different biologic research and biomedical applications, such as surgical devices and drug delivery vehicles.
    Matched MeSH terms: Disk Diffusion Antimicrobial Tests
  9. Fulltext Discovery of potential anti-infectives against Staphylococcus aureus using a Caenorhabditis elegans infection model
    Kong C, Yehye WA, Abd Rahman N, Tan MW, Nathan S
    BMC Complement Altern Med, 2014;14:4.
    PMID: 24393217 DOI: 10.1186/1472-6882-14-4
    The limited antibiotic options for effective control of methicillin-resistant Staphylococcus aureus infections has led to calls for new therapeutic approaches to combat this human pathogen. An alternative approach to control MRSA is through the use of anti-infective agents that selectively disrupt virulence-mediated pathways without affecting microbial cell viability or by modulating the host natural immune defenses to combat the pathogen.
    Matched MeSH terms: Disk Diffusion Antimicrobial Tests
  10. Fulltext Free radical scavenging, antimicrobial and immunomodulatory activities of Orthosiphon stamineus
    Alshawsh MA, Abdulla MA, Ismail S, Amin ZA, Qader SW, Hadi HA, et al.
    Molecules, 2012;17(5):5385-95.
    PMID: 22569417 DOI: 10.3390/molecules17055385
    Orthosiphon stamineus is considered an important traditional folk medicine. In this study ethanol and aqueous extracts of O. stamineus were evaluated in vitro for their antioxidant, antimicrobial as well as for their immunomodulatory properties on human peripheral blood mononuclear cells (PBMCs). The DPPH radical scavenging method was used for the determination of antioxidant activity, while the antibacterial efficacy was investigated by both disc diffusion method and Minimum Inhibitory Concentration (MIC) against four bacterial strains (Gram-positive and Gram-negative). Furthermore, the immunomodulatory potential of the extracts was investigated through the MTT assay. Aqueous extract of O. stamineus exhibited significant free radical scavenging activity with IC₅₀ 50 9.6 µg/mL, whereas the IC₅₀ for the ethanol extract was 21.4 µg/mL. The best antimicrobial activity was shown by the aqueous extract of O. stamineus against Staphylococcus aureus, with inhibition zone of 10.5 mm and MIC value 1.56 mg/mL. Moreover, the results observed from the MTT assay showed that both plant extracts stimulated the PBMCs proliferation in vitro in a concentration-dependent manner, but the aqueous extract has remarkable activity against PBMCs. These findings indicate that O. stamineus showed high antioxidant activity and may be considered as an immunomodulatory agent.
    Matched MeSH terms: Disk Diffusion Antimicrobial Tests
  11. Evaluation of biological activities of Alpinia mutica Roxb. and its chemical constituents
    Mustahil NA, Sukari MA, Abdul AB, Ali NA, Lian GE
    Pak J Pharm Sci, 2013 Mar;26(2):391-5.
    PMID: 23455212
    Phytochemicals investigation on rhizomes of Alpinia mutica has afforded five compounds namely 5,6-dehydrokawain (1), flavokawin B (2), pinostrobin (3) and pinocembrin (4) together with β-sitosterol (5). All crude extracts of the plant demonstrated strong cytotoxicity against CEMss (human T4 lymphoblastoid) cancer cells with IC50 values less than 19 μg/mL, while flavokawin B (2) was the most cytotoxic isolate with IC50 value 1.86±0.37 μg/mL. Most of the crude extracts and isolated compounds showed weak activity in antimicrobial and diphenylpicrylhydrazyl (DPPH) radical scavenging activity tests.
    Matched MeSH terms: Disk Diffusion Antimicrobial Tests
  12. Fulltext Changing antibiotic resistance profile of Staphylococcus aureus isolated from HIV patients (2012-2017) in Southern India
    Chinnambedu RS, Marimuthu RR, Sunil SS, Amrose P, Ramachandran V, Pachamuthu B
    J Infect Public Health, 2020 Jan;13(1):75-79.
    PMID: 31402312 DOI: 10.1016/j.jiph.2019.06.015
    PURPOSE: Emergence of multidrug-resistant and methicillin-resistant Staphylococcus aureus (MRSA) infections in HIV patients limit the treatment options and challenge the clinical management of infections. The periodic monitoring of S. aureus infections and its drug resistance profile in HIV patients are of paramount importance in clinical management.

    MATERIALS AND METHODS: A total of 7204 clinical specimens from HIV patients from 2012 to 2017 were processed for the isolation of S. aureus strains using conventional culture techniques and cultures were identified using standard biochemical test. Antibiotic susceptibility of S. aureus strains was tested by Kirby-Bauer disk diffusion method.

    RESULTS: A total of 380 (5.3%) S. aureus strains were isolated from HIV patients in the study period. High percentage of S. aureus strains were isolates from urine (69.5%) specimen and 58.4% of S. aureus infections were noted among hospitalized patients. Antibiotic susceptibility profile reveals S. aureus was highly resistant to penicillin (95.2%) followed by cephalexin (84.6%). Methicillin resistance was highly observed in the year 2017 (86%) and the rate of MRSA steadily increasing from 51.8% in 2012 to 86% in 2017. Significant increase of S. aureus infections (35%; p<0.001) and MRSA (76%; p=0.0007) were observed in the year 2016.

    CONCLUSIONS: This study reports the increasing trends of S. aureus infections and MRSA among HIV patients from Southern India. Multidrug-resistance profile of S. aureus could complicate the selection of proper antibiotic regimens and time cure of HIV patients.

    Matched MeSH terms: Disk Diffusion Antimicrobial Tests
  13. Detection of mobile colistin-resistance gene variants (mcr-1 and mcr-2) in urinary tract pathogens in Bangladesh: the last resort of infectious disease management colistin efficacy is under threat
    Ara B, Urmi UL, Haque TA, Nahar S, Rumnaz A, Ali T, et al.
    Expert Rev Clin Pharmacol, 2021 Apr;14(4):513-522.
    PMID: 33691556 DOI: 10.1080/17512433.2021.1901577
    Background: Currently, colistin-resistant pathogens emerged has become a global health concern. This study assessed the distribution of mcr-1 to mcr-5 variants with the phenotypic colistin-resistance in bacterial isolates from urinary tract infection (UTI) patients in Bangladesh.Methods: A cross-sectional study was conducted between April 2017 and March 2018 to enroll uncomplicated UTI patients, and 142 urine samples were analyzed. Uropathogens were identified using the API-20E biochemical panel and 16s rRNA gene sequencing. Polymerase chain reactions detected the mcr gene variants in the UTI isolates. The phenotypic colistin-susceptibility was determined by the Kirby-Bauer disc-diffusion method and the minimal inhibitory concentration (MIC) measurement.Results: The combined carriage of mcr-1 and mcr-2 genes in 11.4% (14/123) of urinary tract pathogens. The mcr-positive pathogens include five Escherichia coli, three Klebsiella pneumoniae, three Pseudomonas putida, two Enterobacter cloacae, and one Enterobacter hormaechei. The mcr-positive variant showed significantly higher phenotypic colistin resistance with MIC between >16 µg/mL and >128 µg/mL (p
    Matched MeSH terms: Disk Diffusion Antimicrobial Tests
  14. Dissemination of Trimethoprim-Sulfamethoxazole Drug Resistance Genes Associated with Class 1 and Class 2 Integrons Among Gram-Negative Bacteria from HIV Patients in South India
    Ramesh Kumar MR, Arunagirinathan N, Srivani S, Dhanasezhian A, Vijaykanth N, Manikandan N, et al.
    Microb Drug Resist, 2017 Jul;23(5):602-608.
    PMID: 27854149 DOI: 10.1089/mdr.2016.0034
    The antibiotic, trimethoprim-sulfamethoxazole (TMP-SMX), is generally used for prophylaxis in HIV individuals to protect them from Pneumocystis jiroveci infection. Long-term use of TMP-SMX develops drug resistance among bacteria in HIV patients. The study was aimed to detect the TMP-SMX resistance genes among gram-negative bacteria from HIV patients. TMP-SMX-resistant isolates were detected by the Kirby-Bauer disc diffusion method. While TMP resistance genes such as dfrA1, dfrA5, dfrA7, and dfrA17 and SMX resistance genes such as sul1 and sul2 were detected by multiplex PCR, class 1 and class 2 integrons were detected by standard monoplex PCR. Of the 151 TMP-SMX-resistant bacterial isolates, 3 were positive for sul1 alone, 48 for sul2 alone, 11 for dfrA7 alone, 21 for sul1 and sul2, 1 for sul1 and dfrA7, 23 for sul2 and dfrA7, 2 for sul2 and dfrA5, 41 for sul1, sul2, and dfrA7, and 1 for sul2, dfrA5, and dfrA7. Of 60 TMP-SMX-resistant isolates positive for integrons, 44 had class 1 and 16 had class 2 integrons. It was found that the prevalence of sul genes (n = 202; p 
    Matched MeSH terms: Disk Diffusion Antimicrobial Tests
  15. Fulltext Antimicrobial activity of Nigella sativa L. seed oil against multi-drug resistant Staphylococcus aureus isolated from diabetic wounds
    Emeka LB, Emeka PM, Khan TM
    Pak J Pharm Sci, 2015 Nov;28(6):1985-90.
    PMID: 26639493
    Microbial resistance to existing antibiotics has led to an increase in the use of medicinal plants that show beneficial effects for various infectious diseases. The study evaluates the susceptibility of multidrug resistant Staphylococcus aureus to Nigella sativa oil. Staphylococcus aureus was isolated from 34 diabetic patient's wounds attending the Renaissance hospital, Nsukka, Southeast Nigeria. The isolates were characterized and identified using standard microbiological techniques. Isolates were cultured and a comparative In vitro antibiotic susceptibility test was carried out using the disk diffusion method. Of the 34 samples collected, 19(56%) showed multidrug resistance to the commonly used antibiotics. Nigella sativa oil was then studied for antibacterial activity against these multidrug resistant isolates of Staphylococcus aureus in varying concentration by well diffusion method. The oil showed pronounced dose dependent antibacterial activity against the isolates. Out of 19 isolates, 8(42%) were sensitive to undiluted oil sample; 4(21%) of these showed sensitivity at 200 mg/ml, 400 mg/ml and 800 mg/ml respectively. Eleven (58%) of the isolates were completely resistant to all the oil concentrations. The present study, reports the isolation of multi-drug resistant S. aureus from diabetic wounds and that more than half of isolates were susceptible to different concentrations N. sativa oil.
    Matched MeSH terms: Disk Diffusion Antimicrobial Tests
  16. Fulltext A Fatal Case of Candida auris and Candida tropicalis Candidemia in Neutropenic Patient
    Mohd Tap R, Lim TC, Kamarudin NA, Ginsapu SJ, Abd Razak MF, Ahmad N, et al.
    Mycopathologia, 2018 Jun;183(3):559-564.
    PMID: 29383574 DOI: 10.1007/s11046-018-0244-y
    We report a fatal case of Candida auris that was involved in mixed candidemia with Candida tropicalis, isolated from the blood of a neutropenic patient. Identification of both isolates was confirmed by amplification and sequencing of internal transcribed spacer and D1/D2 domain of large subunit in rRNA gene. Antifungal susceptibility test by E-test method revealed that C. auris was resistant to amphotericin B, anidulafungin, caspofungin, fluconazole, itraconazole and voriconazole. On the other hand, C. tropicalis was sensitive to all antifungal tested. The use of chromogenic agar as isolation media is vital in detecting mixed candidemia.
    Matched MeSH terms: Disk Diffusion Antimicrobial Tests
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