Displaying publications 1 - 20 of 153 in total

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  1. Isolation and identification of a new intracellular antimicrobial peptide produced by Paenibacillus alvei AN5
    Alkotaini B, Anuar N, Kadhum AA, Sani AA
    World J Microbiol Biotechnol, 2014 Apr;30(4):1377-85.
    PMID: 24272828 DOI: 10.1007/s11274-013-1558-z
    A wild-type, Gram-positive, rod-shaped, endospore-forming and motile bacteria has been isolated from palm oil mill sludge in Malaysia. Molecular identification using 16S rRNA gene sequence analysis indicated that the bacteria belonged to genus Paenibacillus. With 97 % similarity to P. alvei (AUG6), the isolate was designated as P. alvei AN5. An antimicrobial compound was extracted from P. alvei AN5-pelleted cells using 95 % methanol and was then lyophilized. Precipitates were re-suspended in phosphate buffered saline (PBS), producing an antimicrobial crude extract (ACE). The ACE showed antimicrobial activity against Salmonella enteritidis ATCC 13076, Escherichia coli ATCC 29522, Bacillus cereus ATCC 14579 and Lactobacillus plantarum ATCC 8014. By using SP-Sepharose cation exchange chromatography, Sephadex G-25 gel filtration and Tricine SDS-PAGE, the ACE was purified, which produced a ~2-kDa active band. SDS-PAGE and infrared (IR) spectroscopy indicated the proteinaceous nature of the antimicrobial compound in the ACE, and liquid chromatography electrospray ionization mass spectroscopy and de novo sequencing using an automatic, Q-TOF premier system detected a peptide with the amino acid sequence F-C-K-S-L-P-L-P-L-S-V-K (1,330.7789 Da). This novel peptide was designated as AN5-2. The antimicrobial peptide exhibited stability from pH 3 to 12 and maintained its activity after being heated to 90 °C. It also remained active after incubation with denaturants (urea, SDS and EDTA).
    Matched MeSH terms: Gram-Negative Bacteria/drug effects
  2. Antibacterial evaluation of silver nanoparticles synthesized from lychee peel: individual versus antibiotic conjugated effects
    Perveen S, Safdar N, Chaudhry GE, Yasmin A
    World J Microbiol Biotechnol, 2018 Jul 14;34(8):118.
    PMID: 30008019 DOI: 10.1007/s11274-018-2500-1
    This paper describes the extracellular synthesis of silver nanoparticles from waste part of lychee fruit (peel) and their conjugation with selected antibiotics (amoxicillin, cefixim, and streptomycin). FTIR studies revealed the reduction of metallic silver and stabilization of silver nanoparticles and their conjugates due to the presence of CO (carboxyl), OH (hydroxyl) and CH (alkanes) groups. The size of conjugated nanoparticles varied ranging from 3 to 10 nm as shown by XRD. TEM image revealed the spherical shape of biosynthesized silver nanoparticles. Conjugates of amoxicillin and cefixim showed highest antibacterial activity (147.43 and 107.95%, respectively) against Gram-negative bacteria i.e. Alcaligenes faecalis in comparison with their control counterparts. The highest reduction in MIC was noted against Gram-positive strains i.e. Enterococcus faecium (75%) and Microbacterium oxydans (75%) for amoxicillin conjugates. Anova two factor followed by two-tailed t test showed non-significant results both in case of cell leakage and protein estimation between nanoparticles and conjugates of amoxicillin, cefixime and streptomycin. In case of MDA release, non-significant difference among the test samples against the selected strains. Our study found green-synthesized silver nanoparticles as effective antibacterial bullet against both Gram positive and Gram negative bacteria, but they showed a more promising effect on conjugation with selected antibiotics against Gram negative type.
    Matched MeSH terms: Gram-Negative Bacteria/drug effects
  3. Removal efficiency of Gram-positive and Gram-negative bacteria using a natural coagulant during coagulation, flocculation, and sedimentation processes
    Sha'arani S, Azizan SNF, Md Akhir FN, Muhammad Yuzir MA, Othman N, Zakaria Z, et al.
    Water Sci Technol, 2019 Nov;80(9):1787-1795.
    PMID: 32039910 DOI: 10.2166/wst.2019.433
    Staphylococcus sp. as Gram-positive and Escherichia coli as Gram-negative are bacterial pathogens and can cause primary bloodstream infections and food poisoning. Coagulation, flocculation, and sedimentation processes could be a reliable treatment for bacterial removal because suspended, colloidal, and soluble particles can be removed. Chemical coagulants, such as alum, are commonly used. However, these chemical coagulants are not environmentally friendly. This present study evaluated the effectiveness of coagulation, flocculation, and sedimentation processes for removing Staphylococcus sp. and E. coli using diatomite with standard jar test equipment at different pH values. Staphylococcus sp. demonstrated 85.61% and 77.23% significant removal in diatomite and alum, respectively, at pH 5. At pH 7, the removal efficiency decreased to 79.41% and 64.13% for Staphylococcus sp. and E. coli, respectively. At pH 9, there was a decrease in Staphylococcus sp. after adding diatomite or alum compared with that of E. coli. The different removal efficiencies of the Gram-positive and Gram-negative bacteria could be owing to the membrane composition and different structures in the bacteria. This study indicates that diatomite has higher efficiency in removing bacteria at pH 5 and can be considered as a potential coagulant to replace alum for removing bacteria by the coagulation process.
    Matched MeSH terms: Gram-Negative Bacteria
  4. Fulltext Clinico-pathology, hematology, and biochemistry responses toward Pasteurella multocida Type B: 2 via oral and subcutaneous route of infections
    Chung EL, Abdullah FF, Adamu L, Marza AD, Ibrahim HH, Zamri-Saad M, et al.
    Vet World, 2015 Jun;8(6):783-92.
    PMID: 27065648 DOI: 10.14202/vetworld.2015.783-792
    Pasteurella multocida a Gram-negative bacterium has been identified as the causative agent of many economically important diseases in a wide range of hosts. Hemorrhagic septicemia is a disease caused by P. multocida serotype B:2 and E:2. The organism causes acute, a highly fatal septicemic disease with high morbidity and mortality in cattle and more susceptible in buffaloes. Therefore, the aim of this study was to investigate the clinical signs, blood parameters, post mortem and histopathology changes caused by P. multocida Type B:2 infections initiated through the oral and subcutaneous routes.
    Matched MeSH terms: Gram-Negative Bacteria
  5. In vitro antimicrobial activity of narasin and monensin in combination with adjuvants against pathogens associated with canine otitis externa
    Chan WY, Hickey EE, Khazandi M, Page SW, Trott DJ, Hill PB
    Vet Dermatol, 2020 Apr;31(2):138-145.
    PMID: 31710159 DOI: 10.1111/vde.12803
    BACKGROUND: The emergence of antimicrobial resistance represents a serious human and animal health risk. Good antimicrobial stewardship is essential to prolong the lifespan of existing antibiotics, and new strategies are required to combat infections in man and animals.

    HYPOTHESIS/OBJECTIVES: To determine the in vitro interaction of ionophores (narasin or monensin) with antimicrobial adjuvants (N-acetylcysteine (NAC), Tris-EDTA or disodium EDTA) against bacterial strains representing pathogens associated with canine otitis externa (OE).

    ANIMAL/ISOLATES: American Type Culture Collection (ATCC) strains Staphylococcus aureus 29213, Pseudomonas aeruginosa 27853 and P. aeruginosa biofilm producer PAO1, and a clinical isolate of Proteus mirabilis from a case of canine OE were tested.

    METHODS AND MATERIALS: A 2D microdilution checkerboard method was used, allowing calculation of fractional inhibitory concentration index (FICI), dose reduction index (DRI) and plotting of isobolograms.

    RESULTS: The combination of narasin with either Tris-EDTA or disodium EDTA produced additive effects (FICI = 0.75) against P. aeruginosa ATCC 27853 and P. aeruginosa biofilm producer ATCC PAO1. An additive effect (FICI = 0.53-0.75) was found against S. aureus ATCC 29213 when narasin or monensin were combined with NAC. The highest DRI (32-fold) was found with monensin/NAC where the MIC of monensin was reduced from 4 to 0.125 μg/mL.

    CONCLUSIONS AND CLINICAL IMPORTANCE: The combination of narasin with Tris-EDTA or disodium EDTA is a promising strategy to inhibit the intrinsic resistance elements of Gram-negative bacteria. These novel combinations potentially could be useful as a multimodal approach to treat mixed infections in canine OE.

    Matched MeSH terms: Gram-Negative Bacteria
  6. Fulltext An efficient approach for the synthesis of novel methyl sulfones in acetic acid medium and evaluation of antimicrobial activity
    Ravi Kumar G, Dasireddy CR, Varala R, Kotra V, Bollikolla HB
    Turk J Chem, 2020;44(5):1386-1394.
    PMID: 33488238 DOI: 10.3906/kim-2003-10
    A series of nine methyl sulphones ( 3a -3 i ) starting from the aldehydes ( 1a-1i ) were synthesized in two consecutive steps. In the first step, preparation of allyl alcohols ( 2a-2i ) from their corresponding aldehydes by the reaction of sodium borohydride in methanol at room temperature is reported. Finally, methyl sulphones are synthesized by condensing sodium methyl sulfinates with allyl alcohols in the presence of BF 3 .Et 2 O in acetic acid medium at room temperature for about 2-3 h. The reaction conditions are simple, yields are high (85%-95%), and the products were obtained with good purity. All the synthesized compounds were characterized by their 1 H, 13 C NMR, and mass spectral analysis. All the title compounds were screened for antimicrobial activity. Among the compounds tested, the compound 3f has inhibited both Gram positive and Gram negative bacteria effectively and compound 3i has shown potent antifungal activity. These promising components may help to develop more potent drugs in the near future for the treatment of bacterial and fungal infections.
    Matched MeSH terms: Gram-Negative Bacteria
  7. Fulltext In vitro antibacterial activity of Quercus infectoria gall extracts against multidrug resistant bacteria
    Wan Nor Amilah WA, Masrah M, Hasmah A, Noor Izani NJ
    Trop Biomed, 2014 Dec;31(4):680-8.
    PMID: 25776593 MyJurnal
    Antimicrobial activities of plants have long been evaluated for their promising use as antimicrobial agent and in minimizing the unwanted resistance effects of microorganisms. The study was conducted to evaluate the antibacterial activity of Quercus infectoria gall crude extracts against multidrug resistant (MDR) bacteria in vitro. The screening test was determined by disc diffusion technique using sterile filter paper discs impregnated with 1 mg/ disc (50 mg/ml) aqueous and ethanol extracts of Q. infectoria galls tested on five selected MDR bacterial strains. The minimum inhibitory concentration (MIC) was determined using the twofold serial micro dilution technique at concentration ranging from 5.00 mg/ml to 0.01 mg/ml. The minimum bactericidal concentration (MBC) was determined by sub culturing the microtitre wells showing no turbidity on the agar plate to obtain the MBC value. Both extracts showed substantial inhibitory effects against methicillin resistant coagulase negative Staphylococcus (MRCoNS) and methicillin resistant Staphylococcus aureus (MRSA). A slightly reduced inhibitory zone diameter was observed with MDR Acinetobacter sp. while no inhibitory effect was displayed among the extended spectrum beta lactamases (ESBL) K. pneumoniae and ESBL E. coli isolates. A significant difference in the zone sizes between both extracts was only observed in MRSA (p < 0.05). The MIC values ranged from 0.08 mg/ml to 0.63 mg/ml for aqueous and ethanol extracts against MRSA, MRCoNS and MDR Acinetobacter sp. while their MBC to MIC ratio values were 2 and less. The Q. infectoria gall extracts have shown very promising in vitro antibacterial activities and may be considered as a potentially good source of antimicrobial agent especially against MDR Gram positive bacteria.
    Matched MeSH terms: Gram-Negative Bacteria/drug effects*
  8. Fulltext Phytochemical and antimicrobial activity of Swietenia mahagoni crude methanolic seed extract
    Sahgal G, Ramanathan S, Sasidharan S, Mordi MN, Ismail S, Mansor SM
    Trop Biomed, 2009 Dec;26(3):274-9.
    PMID: 20237441 MyJurnal
    The present study was designed to evaluate the antibacterial activities of Swietenia mahagoni crude methanolic (SMCM) seed extract. The antimicrobial activity of the oily extract against Gram-positive, Gram-negative, yeast and fungus strains was evaluated based on the inhibition zone using disc diffusion assay, minimal inhibition concentration (MIC) and minimal bactericidal concentration (MBC) values. The crude extract was subjected to various phytochemicals analysis. The demonstrated qualitative phytochemical tests exhibited the presences of common phytocompounds including alkaloids, terpenoids, antraquinones, cardiac glycosides, saponins, and volatile oils as major active constituents. The SMCM seed extract had inhibitory effects on the growth of Candida albicans, Staphylococcus aureus, Pseudomonas aeroginosa, Streptococcus faecalis and Proteus mirabillase and illustrated MIC and MBC values ranging from 25 mg/ml to 50 mg/ml.
    Matched MeSH terms: Gram-Negative Bacteria/drug effects
  9. 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: Gram-Negative Bacteria/classification; Gram-Negative Bacteria/drug effects*
  10. Are secondary forests second-rate? Comparing peatland greenhouse gas emissions, chemical and microbial community properties between primary and secondary forests in Peninsular Malaysia
    Dhandapani S, Ritz K, Evers S, Yule CM, Sjögersten S
    Sci Total Environ, 2019 Mar 10;655:220-231.
    PMID: 30471590 DOI: 10.1016/j.scitotenv.2018.11.046
    Tropical peatlands are globally important ecosystems with high C storage and are endangered by anthropogenic disturbances. Microbes in peatlands play an important role in sustaining the functions of peatlands as a C sink, yet their characteristics in these habitats are poorly understood. This research aimed to elucidate the responses of these complex ecosystems to disturbance by exploring greenhouse gas (GHG) emissions, nutrient contents, soil microbial communities and the functional interactions between these components in a primary and secondary peat swamp forest in Peninsular Malaysia. GHG measurements using closed chambers, and peat sampling were carried out in both wet and dry seasons. Microbial community phenotypes and nutrient content were determined using phospholipid fatty acid (PLFA) and inductively-coupled plasma mass spectrometry (ICP-MS) analyses respectively. CO2 emissions in the secondary peat swamp forest were > 50% higher than in the primary forest. CH4 emission rates were ca. 2 mg m-2 h-1 in the primary forest but the secondary forest was a CH4 sink, showing no seasonal variations in GHG emissions. Almost all the nutrient concentrations were significantly lower in the secondary forest, postulated to be due to nutrient leaching via drainage and higher rates of decomposition. Cu and Mo concentrations were negatively correlated with CO2 and CH4 emissions respectively. Microbial community structure was overwhelmingly dominated by bacteria in both forest types, however it was highly sensitive to land-use change and season. Gram-positive and Gram-negative relative abundance were positively correlated with CO2 and CH4 emissions respectively. Drainage related disturbances increased CO2 emissions, by reducing the nutrient content including some with known antimicrobial properties (Cu & Na) and by favouring Gram-positive bacteria over Gram-negative bacteria. These results suggest that the biogeochemistry of secondary peat swamp forest is fundamentally different from that of primary peat swamp forest, and these differences have significant functional impacts on their respective environments.
    Matched MeSH terms: Gram-Negative Bacteria/isolation & purification
  11. Fulltext Antimicrobial properties of erythromycin and colistin impregnated bone cement. An in vitro analysis
    Ruzaimi MY, Shahril Y, Masbah O, Salasawati H
    Med J Malaysia, 2006 Feb;61 Suppl A:21-6.
    PMID: 17042224
    Deep surgical site infection is a devastating consequence of total joint arthroplasty. The use of antibiotic impregnated bone cement is a well-accepted adjunct for treatment of established infection and prevention of deep orthopaedic infection. It allows local delivery of the antibiotic at the cement-bone interface and sustained release of antibiotic provides adequate antibiotic coverage after the wound closure. Preclinical testing, randomised and clinical trials indicate that the use of antibiotic-impregnated bone cement is a potentially effective strategy in reducing the risk of deep surgical site infection following total joint arthroplasty. The purpose of this study was to assess antibacterial activity of erythromycin and colistin impregnated bone cement against strains of organisms' representative of orthopaedic infections including Gram-positive and Gram-negative aerobic organisms: Staphylococcus aureus, coagulase-negative Staphylococci, Enterococcus sp., Proteus sp., Klebsiella sp., Pseudomonas sp., and Escherichia coli. Pre-blended Simplex P bone cement with the addition of erythromycin and colistin (Howemedica Inc) was mixed thoroughly with 20ml liquid under sterile conditions to produce uniform cylindrical discs with a diameter of 14mm and thickness of 2mm. 24-48 hour agar cultures of Staphylococcus aureus, coagulase-negative Staphylococci, Enterococcus sp.,Proteus sp., Klebsiella sp.,Pseudomonas sp., and Escherichia coli were used for the agar diffusion tests. The agar plates were streaked for confluent growth followed by application of erythromycin and colistin impregnated bone cement disc to each agar plate. The plates were incubated at 30 degrees C and examined at 24, 48, 72 hours, and four and five days after the preparation of the impregnated cement. The susceptibility of Staphylococcus aureus to the control discs was most clearly demonstrated showing a distinct zone of inhibition. The zone observed around coagulase-negative Staphylococci, Klebsiella sp., Pseudomonas sp., and Escherichia coli were also significant. However, there was no zone of inhibition or signs of antibacterial activity at the cemented surface were detected around discs with Enterococcus sp. and Proteus sp. The results showed that Simplex P bone cement with the addition of erythromycin and colistin was effective against most of the broad spectrum organisms encountered during total joint arthroplasty. The activity of Simplex P bone cement impregnated with erythromycin and colistin is mainly during the first 72 hours.
    Matched MeSH terms: Gram-Negative Bacteria/drug effects*
  12. Fulltext Culture-proven bacterial keratitis in a Malaysian general hospital
    Hooi SH, Hooi ST
    Med J Malaysia, 2005 Dec;60(5):614-23.
    PMID: 16515113
    One hundred patients (101 eyes) with culture-proven bacterial keratitis were treated in the Department of Ophthalmology, Hospital Sultanah Aminah, Johor Bahru, over a 4-year period. The majority of patients was male (63%), Malay (60%), from the Johor Bahru district (62%) and aged between 41 to 50 years (20%). The ocular predisposing factors were ocular trauma (41 eyes), ocular surface disease (28 eyes) and contact lens wear (26 eyes). The corneal ulcers were mainly large (50.5%), central (59.4%) and colonized by Gram-negative bacteria (78.1%). The most frequently isolated microorganisms were Pseudomonas aeruginosa (67 eyes), Staphylococcus aureus (12 eyes), Acinetobacter baumanii (6 eyes), Klebsiella pneumoniae (5 eyes), Corynebacterium sp. (3 eyes:) and Streptococcus pneumonliae (3 eyes). Twelve eyes (11.8%) had polymicrobial infection. A good visual outcome occurred in 52.5% of eyes analysed. Prognostic factors for visual outcome include presenting Snellen visual acuity, time to presentation after onset of ocular symptoms, ocular predisposing factor, corneal ulcer location and corneal ulcer size.
    Matched MeSH terms: Gram-Negative Bacteria/isolation & purification*
  13. Fulltext Orthopaedic infections: organisms and antibiotic sensitivity
    Yusof MI, Yusof AH
    Med J Malaysia, 2004 Dec;59(5):574-7.
    PMID: 15889557
    Staphylococcus aureus infection remains the commonest organism causing musculoskeletal infection and antibiotic is the mainstay of treatment apart from adequate and appropriate surgical intervention. The exact figure of antibiotic resistance in orthopaedic practice is not known but it is expected to be higher than previously reported as the use of antibiotics is rampant. Its sensitivity to various antibiotics differs from one center to another making local surveillance necessary. From 66 patients with musculoskeletal infections studied in our centre, Staphylococcus aureus was cultured in 50-65% of patients, depending on the sample taken. Fifteen percent of this were methicillin resistant Staphylococcus aureus (MRSA). Staphylococcus aureus was found to be sensitive to cloxacillin in 95% of patients' sample. MRSA remained highly sensitive to vancomycin, clindamycin and fucidic acid.
    Matched MeSH terms: Gram-Negative Bacteria/drug effects*; Gram-Negative Bacteria/isolation & purification
  14. A comparative study of the in-vitro activity of cefepime and other cephalosporins
    Lim VK, Halijah MY
    Malays J Pathol, 1993 Jun;15(1):65-8.
    PMID: 8277793
    Cefepime is a new cephalosporin antibiotic which is highly active against both Gram-positive and Gram-negative organisms. The purpose of this study was to establish the in-vitro activity of cefepime and three other cephalosporins against recent clinical isolates from patients at the General Hospital Kuala Lumpur. A total of 334 strains comprising Enterobacteriaceae, non-fermentative Gram-negative bacilli and Staphylococcus aureus were tested for their sensitivity to cefepime, cefotaxime, ceftriaxone and ceftazidime. Minimum inhibitory concentrations of the antibiotics were established using an agar dilution method. With the exception of some strains of Flavobacterium meningosepticum, Xanthomonas maltophilia and other non-fermentative Gram-negative bacilli, cefepime was found to be active against a wide range of Gram-negative organisms. Cefepime was as or more active than the other cephalosporins against Acinetobacter, Enterobacteriaceae and methicillin-sensitive Staphylococcus aureus. Strains of Klebsiella and Salmonella that were resistant to the third generation cephalosporins were sensitive to cefepime. Cefepime could be a valuable alternative for the treatment of nosocomial infections due to multiply resistant organisms.
    Matched MeSH terms: Gram-Negative Bacteria/drug effects
  15. Fulltext Preliminary screening of endophytic fungi from medicinal plants in malaysia for antimicrobial and antitumor activity
    Radu S, Kqueen CY
    Malays J Med Sci, 2002 Jul;9(2):23-33.
    PMID: 22844221 MyJurnal
    The screening of antimicrobial activity against Gram-positive bacteria, Gram-negative bacteria, yeast and fungi was carried out on isopropanol extracts prepared from 121 isolates of endophytic fungi isolated from medicinal plants in Malaysia. Sensitivity was found to vary among the microorganisms. Bacillus subtilis, Saccharomyces cerevisiae and Alternaria sp. were susceptible to extracts from three, two and two isolates of endophytic fungi, respectively. None were found effective against Salmonella typhimurium. Sixteen endophytic fungal isolates tested were also found to exhibit antitumor activity in the yeast cell-based assay.
    Matched MeSH terms: Gram-Negative Bacteria
  16. Dynamic interaction of colistin and meropenem on a WT and a resistant strain of Pseudomonas aeruginosa as quantified in a PK/PD model
    Mohamed AF, Kristoffersson AN, Karvanen M, Nielsen EI, Cars O, Friberg LE
    J Antimicrob Chemother, 2016 May;71(5):1279-90.
    PMID: 26850719 DOI: 10.1093/jac/dkv488
    Combination therapy can be a strategy to ensure effective bacterial killing when treating Pseudomonas aeruginosa, a Gram-negative bacterium with high potential for developing resistance. The aim of this study was to develop a pharmacokinetic/pharmacodynamic (PK/PD) model that describes the in vitro bacterial time-kill curves of colistin and meropenem alone and in combination for one WT and one meropenem-resistant strain of P. aeruginosa.
    Matched MeSH terms: Gram-Negative Bacteria
  17. Novel antimicrobial development using genome-scale metabolic model of Gram-negative pathogens: a review
    Chung WY, Zhu Y, Mahamad Maifiah MH, Shivashekaregowda NKH, Wong EH, Abdul Rahim N
    J Antibiot (Tokyo), 2021 02;74(2):95-104.
    PMID: 32901119 DOI: 10.1038/s41429-020-00366-2
    Antimicrobial resistance (AMR) threatens the effective prevention and treatment of a wide range of infections. Governments around the world are beginning to devote effort for innovative treatment development to treat these resistant bacteria. Systems biology methods have been applied extensively to provide valuable insights into metabolic processes at system level. Genome-scale metabolic models serve as platforms for constraint-based computational techniques which aid in novel drug discovery. Tools for automated reconstruction of metabolic models have been developed to support system level metabolic analysis. We discuss features of such software platforms for potential users to best fit their purpose of research. In this work, we focus to review the development of genome-scale metabolic models of Gram-negative pathogens and also metabolic network approach for identification of antimicrobial drugs targets.
    Matched MeSH terms: Gram-Negative Bacteria/drug effects*; Gram-Negative Bacteria/genetics*; Gram-Negative Bacterial Infections/microbiology*
  18. Synthesis and biological evaluation of indole core-based derivatives with potent antibacterial activity against resistant bacterial pathogens
    Hong W, Li J, Chang Z, Tan X, Yang H, Ouyang Y, et al.
    J Antibiot (Tokyo), 2017 Jul;70(7):832-844.
    PMID: 28465626 DOI: 10.1038/ja.2017.55
    The emergence of drug resistance in bacterial pathogens is a growing clinical problem that poses difficult challenges in patient management. To exacerbate this problem, there is currently a serious lack of antibacterial agents that are designed to target extremely drug-resistant bacterial strains. Here we describe the design, synthesis and antibacterial testing of a series of 40 novel indole core derivatives, which are predicated by molecular modeling to be potential glycosyltransferase inhibitors. Twenty of these derivatives were found to show in vitro inhibition of Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus. Four of these strains showed additional activity against Gram-negative bacteria, including extended-spectrum beta-lactamase producing Enterobacteriaceae, imipenem-resistant Klebsiella pneumoniae and multidrug-resistant Acinetobacter baumanii, and against Mycobacterium tuberculosis H37Ra. These four compounds are candidates for developing into broad-spectrum anti-infective agents.
    Matched MeSH terms: Gram-Negative Bacteria/drug effects*
  19. Fulltext A secondary mode of action of polymyxins against Gram-negative bacteria involves the inhibition of NADH-quinone oxidoreductase activity
    Deris ZZ, Akter J, Sivanesan S, Roberts KD, Thompson PE, Nation RL, et al.
    J Antibiot (Tokyo), 2014 Feb;67(2):147-51.
    PMID: 24169795 DOI: 10.1038/ja.2013.111
    Polymyxin B and colistin were examined for their ability to inhibit the type II NADH-quinone oxidoreductases (NDH-2) of three species of Gram-negative bacteria. Polymyxin B and colistin inhibited the NDH-2 activity in preparations from all of the isolates in a concentration-dependent manner. The mechanism of NDH-2 inhibition by polymyxin B was investigated in detail with Escherichia coli inner membrane preparations and conformed to a mixed inhibition model with respect to ubiquinone-1 and a non-competitive inhibition model with respect to NADH. These suggest that the inhibition of vital respiratory enzymes in the bacterial inner membrane represents one of the secondary modes of action for polymyxins.
    Matched MeSH terms: Gram-Negative Bacteria/drug effects*; Gram-Negative Bacteria/enzymology*
  20. Stigmasterol: An adjuvant for beta lactam antibiotics against beta-lactamase positive clinical isolates
    Yenn TW, Arslan Khan M, Amiera Syuhada N, Chean Ring L, Ibrahim D, Tan WN
    Steroids, 2017 Dec;128:68-71.
    PMID: 29104098 DOI: 10.1016/j.steroids.2017.10.016
    The emergence of beta lactamase producing bacterial strains eliminated the use of beta lactam antibiotics as chemotherapeutic alternative. Beta lactam antibiotics can be coupled with non-antibiotic adjuvants to combat these multidrug resistant strains. We study the synergistic antibiotic effect of stigmasterol as adjuvant of ampicillin against clinical isolates. Ampicillin was used in this study as a beta lactam antibiotic model. All test bacteria were beta lactamase producing clinical isolates. The combination showed significantly better antibiotic activity on all bacteria tested. The two test substances have synergistic antibiotic activity, and the effect was observed in both Gram positive and Gram negative bacteria. The synergistic antibiotic effect of stigmasterol and ampicillin was evident by the low fractional inhibitory concentration (FIC) index on Checkerboard Assay. The results suggest that the combination of ampicillin and stigmasterol acts additively in the treatment of infections caused by beta-lactamase producing pathogens. In bacterial growth reduction assay, ampicillin and stigmasterol alone exhibited very weak inhibitory effect on the bacterial growth, relative to ethanol control. Comparatively, combination of stigmasterol-ampicillin greatly reduced the colony counts at least by 98.7%. In conclusion, we found synergistic effects of stigmasterol and ampicillin against beta lactamase producing clinical isolates. This finding is important as it shows potential application of stigmasterol as an antibiotic adjuvant.
    Matched MeSH terms: Gram-Negative Bacteria/drug effects; Gram-Negative Bacteria/pathogenicity
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