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Fulltext L,L-diaminopimelate aminotransferase (DapL): a putative target for the development of narrow-spectrum antibacterial compounds

Triassi AJ, Wheatley MS, Savka MA, Gan HM, Dobson RC, Hudson AO

Front Microbiol, 2014;5:509.
PMID: 25309529 DOI: 10.3389/fmicb.2014.00509

Despite the urgent need for sustained development of novel antibacterial compounds to combat the drastic rise in antibiotic resistant and emerging bacterial infections, only a few clinically relevant antibacterial drugs have been recently developed. One of the bottlenecks impeding the development of novel antibacterial compounds is the identification of new enzymatic targets. The nutritionally essential amino acid anabolic pathways, for example lysine biosynthesis, provide an opportunity to explore the development of antibacterial compounds, since human genomes do not possess the genes necessary to synthesize these amino acids de novo. The diaminopimelate (DAP)/lysine (lys) anabolic pathways are attractive targets for antibacterial development since the penultimate lys precursor meso-DAP (m-DAP) is a cross-linking amino acid in the peptidoglycan (PG) cell wall of most Gram-negative bacteria and lys plays a similar role in the PG of most Gram-positive bacteria, in addition to its role as one of the 20 proteogenic amino acids. The L,L-diaminopimelate aminotransferase (DapL) pathway was recently identified as a novel variant of the DAP/lys anabolic pathways. The DapL pathway has been identified in the pathogenic bacteria belonging to the genus; Chlamydia, Leptospira, and Treponema. The dapL gene has been identified in the genomes of 381 or approximately 13% of the 2771 bacteria that have been sequenced, annotated and reposited in the NCBI database, as of May 23, 2014. The narrow distribution of the DapL pathway in the bacterial domain provides an opportunity for the development and or discovery of narrow spectrum antibacterial compounds.

Matched MeSH terms: Gram-Negative Bacteria
Fulltext Antioxidant and antibacterial activity of Rhoeo spathacea (Swartz) Stearn leaves

Tan JB, Lim YY, Lee SM

J Food Sci Technol, 2015 Apr;52(4):2394-400.
PMID: 25829624 DOI: 10.1007/s13197-013-1236-z

The decoction and infusion of Rhoeo spathacea (Swartz) Stearn leaves have been recognized as a functional food particularly in South America, but has not yet gained international popularity as a beverage. The primary aim of this study was to establish the viability of R. spathacea aqueous leaf extracts as a beverage, in terms of its antioxidant activity and antibacterial activity. The antioxidant contents of aqueous and methanol leaf extracts were evaluated by the total phenolic content (TPC) and total flavonoid content (TFC) assays. The antioxidant activities measured were DPPH radical scavenging activity (FRS), ferric reducing power (FRP) and ferrous ion chelating (FIC) activity. The aqueous leaf extracts in the forms of decoction and infusion, were found to have comparable TPC and antioxidant activity with other herbal teas previously reported by our research group. Both decoction and infusion also exhibited antibacterial activity against six species of Gram positive and four species of Gram negative bacteria, notably methicillin-resistant Staphylococcus aureus and Neisseria gonorrhoeae. A total of four different known phenolic compounds were identified by HPLC and MS, three of which have not been previously reported to be found in this plant. Both the decoction and infusion of the leaves R. spathacea have potential to be popularized into a common beverage.

Matched MeSH terms: Gram-Negative Bacteria
Fulltext Long-term impact of oral surgery with or without amoxicillin on the oral microbiome-A prospective cohort study

Menon RK, Gomez A, Brandt BW, Leung YY, Gopinath D, Watt RM, et al.

Sci Rep, 2019 12 10;9(1):18761.
PMID: 31822712 DOI: 10.1038/s41598-019-55056-3

Routine postoperative antibiotic prophylaxis is not recommended for third molar extractions. However, amoxicillin still continues to be used customarily in several clinical practices worldwide to prevent infections. A prospective cohort study was conducted in cohorts who underwent third molar extractions with (group EA, n = 20) or without (group E, n = 20) amoxicillin (250 mg three times daily for 5 days). Further, a control group without amoxicillin and extractions (group C, n = 17) was included. Salivary samples were collected at baseline, 1-, 2-, 3-, 4-weeks and 3 months to assess the bacterial shift and antibiotic resistance gene changes employing 16S rRNA gene sequencing (Illumina-Miseq) and quantitative polymerase chain reaction. A further 6-month follow-up was performed for groups E and EA. Seven operational taxonomic units reported a significant change from baseline to 3 months for group EA (adjusted p bacteria and β-lactamase resistance genes (TEM-1) was observed over 6 months for any group (adjusted p > 0.05). In conclusion, the salivary microbiome is resilient to an antibiotic challenge by a low-dose regimen of amoxicillin. Further studies evaluating the effect of routinely used higher dose regimens of amoxicillin on gram-negative bacteria and antibiotic resistance genes are warranted.

Matched MeSH terms: Gram-Negative Bacteria/drug effects; Gram-Negative Bacteria/genetics; Gram-Negative Bacteria/isolation & purification
Fulltext Comparative Study of CDST & Multiplex PCR to Detect MBL Producing Gram-Negative Bacilli among VAP Patients Admitted in a Public Medical College Hospital of Bangladesh

Nusrat T, Akter N, Haque M, Rahman NAA, Dewanjee AK, Ahmed S, et al.

Pathogens, 2019 Sep 12;8(3).
PMID: 31547453 DOI: 10.3390/pathogens8030151

BACKGROUND: Ventilator-associated pneumonia (VAP) is the most common nosocomial infection in intensive care units (ICU), which accounts for 25% of all ICU infection. Documenting carbapenem-resistant gram-negative bacilli is very important as these strains may often cause outbreaks in the ICU setting and are responsible for the increased mortality and morbidity or limiting therapeutic options. The classical phenotypic method cannot provide an efficient means of diagnosis of the metallo-β-lactamases (MBLs) producer. Polymerase chain reaction (PCR) assays have lessened the importance of the phenotypic approach by detecting metallo-β-lactamase resistance genes such as New Delhi metallo-β-lactamase (NDM), Imipenemase (IMP), Verona integron-encoded metallo-β-lactamase (VIM), Sao Paulo metallo-β-lactamase (SPM), Germany Imipenemase (GIM).
OBJECTIVE: To compare the results of the Combined Disc Synergy Test (CDST) with that of the multiplex PCR to detect MBL-producing gram-negative bacilli.
MATERIALS AND METHOD: A total of 105 endotracheal aspirates (ETA) samples were collected from the ICU of a public school in Bangladesh. This cross-sectional study was carried out in the Department of Microbiology, Chittagong for quantitative culture, CDST test, and multiplex PCR for blaIMP, blaVIM, blaNDM genes of MBL producers.
RESULTS: Among the 105 clinically suspected VAP cases, the quantitative culture was positive in 95 (90%) and among 95 g-negative bacilli isolated from VAP patients, 46 (48.42%) were imipenem resistant, 30 (65.22%) were MBL producers by CDST, 21 (45.65%) were identified as MBL producers by multiplex PCR.
CONCLUSION: PCR was highly sensitive and specific for the detection of MBL producers.

Matched MeSH terms: Gram-Negative Bacteria
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
Fulltext Bioactive Compounds from the Bornean Endemic Plant Goniothalamus longistipetes

Teo SP, Bhakta S, Stapleton P, Gibbons S

Antibiotics (Basel), 2020 Dec 16;9(12).
PMID: 33339285 DOI: 10.3390/antibiotics9120913

The present study aimed to screen plants for bioactive compounds with potential antibacterial activities. In our efforts to evaluate plants from Borneo, we isolated and elucidated the structures of four natural products from the bioactive fraction of a chloroform extract of Goniothalamus longistipetes using various chromatographic and spectroscopic techniques. The bioactive compounds were identified as a known styryllactone, (+)-altholactone ((2S,3R,3aS,7aS)-3-hydroxy-2-phenyl-2,3,3a,7a-tetrahydrobenzo-5(4H)-5-one) (1), a new styryllactone, (2S,3R,3aS,7aS)-3-hydroxy-2-phenyl-2,3,3a,7a-tetrahydrobenzo-5(4H)-5-one) (2) as well as a new alkaloid, 2,6-dimethoxyisonicotinaldehyde (3) and a new alkenyl-5-hydroxyl-phenyl benzoic acid (4). 1 and 4 showed broad-spectrum anti-bacterial activities against Gram-positive and Gram-negative bacteria as well as acid-fast model selected for this study. Compound 2 only demonstrated activities against Gram-positive bacteria whilst 3 displayed selective inhibitory activities against Gram-positive bacterial strains. Additionally, their mechanisms of anti-bacterial action were also investigated. Using Mycobacterium smegmatis as a fast-growing model of tubercle bacilli, compounds 1, 2 and 4 demonstrated inhibitory activities against whole-cell drug efflux and biofilm formation; two key intrinsic mechanisms of antibiotic resistance. Interestingly, the amphiphilic compound 4 exhibited inhibitory activity against the conjugation of plasmid pKM101 in Escherichia coli using a plate conjugation assay. Plasmid conjugation is a mechanism by which Gram-positive and Gram-negative-bacteria acquire drug resistance and virulence. These results indicated that bioactive compounds isolated from Goniothalamus longistipetes can be potential candidates as 'hits' for further optimisation.

Matched MeSH terms: Gram-Negative Bacteria
Fulltext 4-(2-(1H-Benzo[d]imidazol-2-ylthio)acetamido)-N-(substituted phenyl)benzamides: design, synthesis and biological evaluation

Tahlan S, Ramasamy K, Lim SM, Shah SAA, Mani V, Narasimhan B

BMC Chem, 2019 Dec;13(1):12.
PMID: 31384761 DOI: 10.1186/s13065-019-0533-7

Background: Dihydrofolate reductase (DHFR) is an important target for antimetabolite class of antimicrobials because it participates in purine synthesis. 2-mercaptobenzimidazole (2MBI) has similar structural features as purine nucleotides. Given that benzimidazole and similar heteroaromatics have been broadly examined for their anticancer potential, so, we hereby report the design, synthesis and biological studies (i.e. antimicrobial and anticancer studies) of 2MBI derivatives.
Methodology: The antimicrobial activity of synthesized 2MBI derivatives were evaluated against Gram positive and Gram negative bacterial species as well as fungal species by tube dilution technique whereas their anticancer activity was assessed against human colorectal carcinoma cell line (HCT116) by Sulforhodamine B (SRB) assay. They were also structurally characterized by IR, NMR, MS and elemental analyses.
Results discussion and conclusion: The antimicrobial activity findings revealed that compound N1 (MIC
bs,st,
ca
= 1.27, 2.54, 1.27 µM), N8 (MIC
ec
= 1.43 µM), N22 (MIC
kp,an
= 2.60 µM), N23 and N25 (MIC
sa
= 2.65 µM) exhibited significant antimicrobial effects against tested strains, i.e. Gram-positive, Gram-negative (bacterial) and fungal strains. The anticancer screening results demonstrated that compounds N9, N18 (IC50 = 5.85, 4.53 µM) were the most potent compounds against cancer cell line (HCT116) even more than 5-FU, the standard drug (IC50 = 9.99 µM).

Matched MeSH terms: Gram-Negative Bacteria
Fulltext Complications of Melioidosis: a systematic review

Marilyn Charlene Montini Maluda, Michelle May D. Goroh, Tan, Eric Chee How, Syed Sharizman Syed Abdul Rahim, Richard Avoi, Mohammad Saffree Jeffree, et al.

Borneo Epidemiology Journal, 2020;1(1):5-15.
MyJurnal

Introduction: Melioidosis, also known as Whitmore disease, is caused by the gram-negative bacillus, Burkholderia pseudomallei and remains a public health concern in Southeast Asia and northern parts of Australia. This study attempts to identify all possible complications of melioidosis and its outcomes.
Methods: Literature search was conducted from databases such as PubMed, Science Direct and Scopus from 1st January 2000 to 31st August 2019. Medical Subject Headings (MeSH) search strategy was used with the terms ‘Melioidosis’ or ‘Burkholderia pseudomallei’ and ‘Complications’.
Results: A total of 162 titles were identified and 22 articles were included in the review. Findings showed that among the 22 articles, the ratio of male to female melioidosis incidence was 2.3 to 1, with most cases (86.4%) aged older than 14 years old and showed a mean age of 46 years old. A third (7/22) of the papers reported the involvement of the nervous system as a complication of melioidosis followed by cardiovascular complications. Among the 23 cases reported, 13 had underlying medical conditions with most of them (84.6%) having diabetes mellitus or newly diagnosed with diabetes mellitus. Overall, only one case (4.3%) had resulted in mortality, while 17.4% developed complications and 78.3% managed a full recovery after undergoing treatment for melioidosis.
Conclusion: The most commonly found complication of melioidosis involved the nervous system but patient outcomes were favourable. Rare complications included mycotic aneurysm that can be fatal. Melioidosis can affect almost any organ leading to various complications.

Matched MeSH terms: Gram-Negative Bacteria
Fulltext Screening of selected Malaysian plants against several food borne pathogen bacteria

International Food Research Journal, 2011;18(3):1195-1201.
MyJurnal

This study was conducted to evaluate antimicrobial properties of ethanolic extracts of the leaves of Nephelium lappaceum, Curcuma longa, Cinnamomun cassia, Durio zibethinus, Vitex trifolia, Amaranthus tricolor, Syzygium samarangense and Manihot esculenta. Antibacterial properties of the extracts were studied against fifteen strains of different gram positive and gram negative pathogenic bacteria, including Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Vibrio para, and Escherichia coli using the agar disk diffusion method. Among the tested extracts, only Amaranthus tricolor exhibited specific inhibition of one of the tested bacteria; Bacillus cereus. Using the microdilution method, its minimum inhibitory concentration (MIC) value was determined to be 20 mg/mL.

Matched MeSH terms: Gram-Negative Bacteria
Fulltext Synergistic effects of Persicaria odorata (daun kesom) leaf extracts with standard antibiotics on pathogenic bacteria

Ridzuan, P.M., Hairul Aini Hamzah, Anis Shah, Norazian Mohd Hassan, Baharudin Roesnita

International Medical Journal Malaysia, 2017;16(2):27-32.
MyJurnal

Antibacterial activity of different types of P. odorata leaf extracts was evaluated in combination with
standard antibiotics. Persicaria. odorata leaves were extracted with n-hexane (n-hex), dichloromethane
(DCM) and methanol (MeOH). Each extract was applied on vancomycin (30µg), erythromycin (15µg) and
gentamicin (10µg) discs, respectively. Disk diffusion method was used to evaluate the synergistic activity of
each combination on Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes,
Streptococcus pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, and Escherichia coli. Minimum
inhibitory concentration (MIC) and gas chromatography mass spectrometry (GCMS) analysis was performed on
the active extract. Synergistic effects seen were mainly from the n-hex+antibiotics combinations, mainly on
the Gram-positive bacteria (7 additive, 5 antagonistic), with MIC range from 50 µg/ml to 100 µg/ml, as well
as Gram-negative bacteria (2 additive, 2 indifferent, 5 antagonistic). In particular, synergism showed by the
combination of n-hex+van were all additive against the susceptible bacteria. DCM extract combination
showed synergistic effects on three Gram-positive species (S. aureus, S. epidermidis, S. pyogenes).
Meanwhile, MeOH+antibiotics combination showed significant additive synergistic effects (p

Matched MeSH terms: Gram-Negative Bacteria
Fulltext In Vitro Antimicrobial Activity of Green Synthesized Silver Nanoparticles Against Selected Gram-negative Foodborne Pathogens

Loo YY, Rukayadi Y, Nor-Khaizura MA, Kuan CH, Chieng BW, Nishibuchi M, et al.

Front Microbiol, 2018;9:1555.
PMID: 30061871 DOI: 10.3389/fmicb.2018.01555

Silver nanoparticles (AgNPs) used in this study were synthesized using pu-erh tea leaves extract with particle size of 4.06 nm. The antibacterial activity of green synthesized AgNPs against a diverse range of Gram-negative foodborne pathogens was determined using disk diffusion method, resazurin microtitre-plate assay (minimum inhibitory concentration, MIC), and minimum bactericidal concentration test (MBC). The MIC and MBC of AgNPs against Escherichia coli, Klebsiella pneumoniae, Salmonella Typhimurium, and Salmonella Enteritidis were 7.8, 3.9, 3.9, 3.9 and 7.8, 3.9, 7.8, 3.9 μg/mL, respectively. Time-kill curves were used to evaluate the concentration between MIC and bactericidal activity of AgNPs at concentrations ranging from 0×MIC to 8×MIC. The killing activity of AgNPs was fast acting against all the Gram-negative bacteria tested; the reduction in the number of CFU mL-1 was >3 Log10 units (99.9%) in 1-2 h. This study indicates that AgNPs exhibit a strong antimicrobial activity and thus might be developed as a new type of antimicrobial agents for the treatment of bacterial infection including multidrug resistant bacterial infection.

Matched MeSH terms: Gram-Negative Bacteria
Fulltext Antimicrobial activities of silver nanoparticles bio-synthesized from diatom Amphora sp.

Tevan, R., Govindaraju, Mugilan, Jayakumar, Saravanan, Govindan, Natanamurugaraj, Mohd Hasbi Ab. Rahim, Maniam, Gaanty Pragas, et al.

Journal of Engineering and Science Research, 2017;1(2):176-184.
MyJurnal

A biological method was employed to synthesize silver nanoparticles through marine diatom Amphora sp. Antimicrobial efficacy test against different pathogenic bacteria were performed through synthesized silver nanoparticles. The physio-chemical properties of synthesized silver nanoparticles were studied using analytical techniques such as UV-Vis spectrophotometer, Field Emission Scanning Electron Microscopy (FESEM), EnergyDispersive X-ray Spectroscopy (EDX) and Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Powder Diffraction (XRD). UV-Vis color intensity study and higher magnification of the Field Emission Scanning Electron Microscopy image showed the synthesized silver nanoparticles were rod shaped with a size range from 42 nm to 46 nm. The synthesized nanoparticles exhibited antibacterial activities in varying magnitudes. About 10 mg/ml of silver nanoparticles were able to inhibit the growth of gram-negative bacteria while gram-positive bacteria were resistant towards similar concentrations of silver nanoparticles.

Matched MeSH terms: Gram-Negative Bacteria
Synthesis of ZnO nanoparticles with chitosan as stabilizing agent and their antibacterial properties against Gram-positive and Gram-negative bacteria

Yusof NAA, Zain NM, Pauzi N

Int J Biol Macromol, 2019 Mar 01;124:1132-1136.
PMID: 30496864 DOI: 10.1016/j.ijbiomac.2018.11.228

Antibacterial activity of zinc oxide (ZnO) nanoparticles have received significant interest, particularly by the implementation of nanotechnology to synthesize particles in nanometer region. ZnO nanoparticles were successfully synthesized through microwave heating by using chitosan as a stabilizing agent and characterized by UV-vis, FTIR, XRD and FESEM-EDX. The aim of the present study is to determine the antibacterial activity of ZnO nanoparticles against Gram-positive bacterium Staphylococcus aureus (S. aureus) and Gram-negative bacterium Escherichia coli (E. coli). The antibacterial effect of ZnO nanoparticles was investigated for the inhibition zone and inactivation of cell growth. The absorption of ZnO nanoparticles was found to be around 360 nm. FTIR results showed the stretching mode of ZnO nanoparticles at 475 cm-1 of the absorption band. EDX results indicated that ZnO nanoparticles have been successfully formed with an atomic percentage of zinc and oxygen at 23.61 and 46.57% respectively. X-ray diffraction result was confirmed the single-phase formation of ZnO nanoparticles and the particle sizes were observed to be around 50 to 130 nm. The results showed that ZnO nanoparticles have displayed inhibition zone of 16 and 13 mm against S. aureus and E. coli respectively. Gram-negative bacteria seemed to be more resistant to ZnO nanoparticles than Gram-positive bacteria.

Matched MeSH terms: Gram-Negative Bacteria
Fulltext Chemical and antibacterial data of synthesized thioureido derivatives

Kadir MA, Ramli R, Yusof MSM, Ismail N, Ngah N, Haris NSH

Data Brief, 2019 Dec;27:104651.
PMID: 31700958 DOI: 10.1016/j.dib.2019.104651

This paper provided comprehensive data on spectroscopic and antibacterial activities of thioureido compounds which are relevant with research article entitled "Synthesis, Spectroscopic Studies and Antibacterial Activity of New Lauroyl Thiourea Amino Acid Derivatives" [1]. Based on the reported study, four new thioureido derivatives, namely 3-(3-dodecanoyl-thioureido)propionic acid (R1), 2-(3-dodecanoyl-thioureido)-3-methyl butyric acid (R2), (3-dodecanoyl-thioureido)acetic acid (R3) and 2-(3-dodecanoyl-thioureido)-3-phenyl propionic acid (R4) were characterized by elemental analysis, Fourier Transform Infrared (FTIR), 1H Nuclear Magnetic Resonance (1H NMR) and 13C Nuclear Magnetic Resonance (13C NMR), and Ultraviolet Visible spectroscopy (UV-Vis). The preliminary results from antibacterial assay which were tested against Gram-positive bacteria such as Bacillus subtilis, Staphylococcus epidermidis, Staphylococcus aureus and Gram-negative bacteria such as Escherichia coli, Salmonella typhimurium are also described.

Matched MeSH terms: Gram-Negative Bacteria
Fulltext Behavior of schmutzdecke with varied filtration rates of slow sand filter to remove total coliforms

Matuzahroh N, Fitriani N, Ardiyanti PE, Kuncoro EP, Budiyanto WD, Isnadina DRM, et al.

Heliyon, 2020 Apr;6(4):e03736.
PMID: 32280804 DOI: 10.1016/j.heliyon.2020.e03736

The previous research showed that slow sand filtration (SSF) can remove the total coli by approximately 99% because of the schmutzecke layer in the filter. The presented study aimed to complete the previous research on SSF, especially on the schmuztdecke layer mechanism, to remove total coli. Total coli is a parameter of water quality standard in Indonesia, and the behavior of schmutzdecke affects the total coli removal. In the present study, the raw water from Amprong River was treated using horizontal roughing filter (HRF) and SSF. The variations in SSF rate used were 0.2 and 0.4 m/h. Total coliforms were analyzed using the most probable number test, and schmutzdecke visualization was conducted through scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX). The best coliform concentration in water treated by the combination of HRF and SSF was 4,386 colonies per 100 mL of sample using the filtration rate of 0.2 m/h, and its removal efficiency was 99.60%. However, the quality of water treated by the combination of HRF and SSF did not meet the drinking water quality standard because the removal of total coli must be 100%. The SEM-EDX visualization results in schmutzdecke showed that the average bacteria in the schmutzdecke layer were small, white, opaque, and circular, with entire edge and flat elevation. The Gram test results showed that the schmutzdecke bacteria consisted of Gram-positive and Gram-negative bacteria with basil as the common cell form.

Matched MeSH terms: Gram-Negative Bacteria
Fulltext Bio-Mediated Synthesis of Reduced Graphene Oxide Nanoparticles from Chenopodium album: Their Antimicrobial and Anticancer Activities

Umar MF, Ahmad F, Saeed H, Usmani SA, Owais M, Rafatullah M

Nanomaterials (Basel), 2020 Jun 01;10(6).
PMID: 32492878 DOI: 10.3390/nano10061096

A novel method of preparing reduced graphene oxide (RGOX) from graphene oxide (GOX) was developed employing vegetable extract, Chenopodium album, as a reducing and stabilizing agent. Chenopodium album is a green leafy vegetable with a low shelf life, fresh leaves of this vegetable are encouraged to be used due to high water content. The previously modified 'Hummers method' has been in practice for the preparation of GOX by using precursor graphite powder. In this study, green synthesis of RGOX was functionally verified by employing FTIR and UV-visible spectroscopy, along with SEM and TEM. Our results demonstrated typical morphology of RGOX stacked in layers that appeared as silky, transparent, and rippled. The antibacterial activity was shown by analyzing minimal inhibitory concentration values, agar diffusion assay, fluorescence techniques. It showed enhanced antibacterial activity against Gram-positive and Gram-negative bacteria in comparison to GOX. It has also been shown that the synthesized compound exhibited enhanced antibiofilm activity as compared to its parent compound. The efficacy of RGOX and GOX has been demonstrated on a human breast cancer cell line, which suggested RGOX as a potential anticancer agent.

Matched MeSH terms: Gram-Negative Bacteria
Phomopsidione-Loaded Chitosan Polyethylene Glycol (PEG) Nanocomposite Dressing for Pressure Ulcers

Chin IBI, Yenn TW, Ring LC, Lazim Y, Tan WN, Rashid SA, et al.

J Pharm Sci, 2020 09;109(9):2884-2890.
PMID: 32534882 DOI: 10.1016/j.xphs.2020.06.005

Pressure ulcers are commonly associated with microbial infections on the wounds which require an effective wound dressing for treatment. Thus far, the available silver dressing has shown tremendous result, however, it may cause argyria and complicate the internal organ function. Hence, our study aims to develop and characterize phomopsidione-loaded chitosan-polyethylene glycol nanocomposite hydrogel (C/PEG/Ph) as an antimicrobial dressing. Physically, the C/PEG/Ph hydrogel demonstrated a uniform light blue color, soft, flexible, and elastic, with no aggregation form. The evaluation via Fourier Transform Infrared (FTIR) exposed the C/PEG/Ph hydrogel has a notable shift towards lower frequency at 1600 and 1554 cm-1. For drug release test, the phomopsidione attained plateau at 24 h, with a total release of 67.9 ± 6.4% from the C/PEG/Ph hydrogel. There was a null burst release effect discovered throughout the experimental period. The C/PEG/Ph hydrogel showed significant results against all 4 Gram-negative bacteria and 1 yeast, with 99.99-100% reduction of microbial growth. The findings revealed that the C/PEG/Ph hydrogel can potentially act as an antimicrobial dressing for pressure ulcers.

Matched MeSH terms: Gram-Negative Bacteria
Fulltext The distribution and characteristics of bacteria in recreational river water of a community resort in Baram, Sarawak, Malaysian Borneo

Lihan, S., Tian, P.K,, Chiew, T.S., Ching, C.L., Shahbudin, A., Hussain, H., et al.

International Food Research Journal, 2017;24(5):2238-2245.
MyJurnal

Enterobacteriaceae is a large family within the Gram-negative bacteria that primarily inhabits in the gastrointestinal tract of human and animals. The bacteria within this group are readily survived in the environment with some species found living free in the water where energy sources are scarce, making them ideal indicators for faecal contamination of the river water. Some species within the family have been used as indicator for the presence of pathogenic bacteria whilst on the other hand some species have been directly associated with various diseases in human and animals. The main aim of this research study was to determine the distribution and characteristics of the Enterobacteriaceae in water samples collected from river and waterfalls within a community resort. The health risk associated with the bacteria was analysed with regard to their susceptibility to antibiotics. Samples were collected from surface water and water falling down directly from waterfalls of river within the community resort. The samples collected were plated onto Eosine Methylene Blue agar (EMBA) for the isolation of the Enterobacteriaceae. Bacterial colonies growing on the agar were randomly picked, purified, stocked and then identified using API 20E identification kit. DNA fingerprinting using (GTG)5-PCR was utilised to determine their genetic profiles before the isolates were grouped into a dendrogram using RAPDistance software package. The level of antibiotic susceptibility of the bacteria isolates was analysed using disc diffusion technique. This study confirmed the presence of Enterobacter, Klebsiella, Citrobacter, Pantoea and Serratia in the water samples with their single and multiple antibiotic resistance and susceptible characteristics. The dendrogram presented in this study shows genetic similarities and differences among the strains, suggesting while there is a potential for single distribution of a clone, there is also possibility of the distribution of different strains within species in the water environment. Therefore, awareness on the potential risk associated with genetically diverse intermediate and resistant enteric bacteria in the recreational water should be communicated to the public especially communities within the study area.

Matched MeSH terms: Gram-Negative Bacteria
Fulltext Impact of COVID-19 pandemic on multidrug resistant gram positive and gram negative pathogens: A systematic review

Abubakar U, Al-Anazi M, Alanazi Z, Rodríguez-Baño J

J Infect Public Health, 2023 Mar;16(3):320-331.
PMID: 36657243 DOI: 10.1016/j.jiph.2022.12.022

BACKGROUND: There is paucity of data describing the impact of COVID-19 pandemic on antimicrobial resistance. This review evaluated the changes in the rate of multidrug resistant gram negative and gram positive bacteria during the COVID-19 pandemic.
METHODS: A search was conducted in PubMed, Science Direct, and Google Scholar databases to identify eligible studies. Studies that reported the impact of COVID-19 pandemic on carbapenem-resistant Acinetobacter baumannii (CRAB), carbapenem-resistant Enterobacteriaceae (CRE), extended-spectrum beta-lactamase inhibitor (ESBL)-producing Enterobacteriaceae, vancomycin-resistant enterococci (VRE), methicillin-resistant Staphylococcus aureus (MRSA) and carbapenem-resistant Pseudomonas aeruginosa (CPE) were selected. Studies published in English language from the start of COVID-19 pandemic to July 2022 were considered for inclusion.
RESULTS: Thirty eligible studies were selected and most of them were from Italy (n = 8), Turkey (n = 3) and Brazil (n = 3). The results indicated changes in the rate of multidrug resistant bacteria, and the changes varied between the studies. Most studies (54.5%) reported increase in MRSA infection/colonization during the pandemic, and the increase ranged from 4.6 to 170.6%. Five studies (55.6%) reported a 6.8-65.1% increase in VRE infection/colonization during the pandemic. A 2.4-58.2% decrease in ESBL E. coli and a 1.8-13.3% reduction in ESBL Klebsiella pneumoniae was observed during the pandemic. For CRAB, most studies (58.3%) reported 1.5-621.6% increase in infection/colonization during the pandemic. Overall, studies showed increase in the rate of CRE infection/colonization during the pandemic. There was a reduction in carbapenem-resistant E. coli during COVID-19 pandemic, and an increase in carbapenem-resistant K. pneumoniae. Most studies (55.6%) showed 10.4 - 40.9% reduction in the rate of CRPA infection during the pandemic.
CONCLUSION: There is an increase in the rate of multidrug resistant gram positive and gram negative bacteria during the COVID-19 pandemic. However, the rate of ESBL-producing Enterobacteriaceae and CRPA has decrease during the pandemic. Both infection prevention and control strategies and antimicrobial stewardship should be strengthen to address the increasing rate of multidrug resistant gram positive and gram negative bacteria.

Matched MeSH terms: Gram-Negative Bacteria
Elucidating the structural, catalytic, and antibacterial traits of Ficus carica and Azadirachta indica leaf extract-mediated synthesis of the Ag/CuO/rGO nanocomposite

Fayyaz Z, Farrukh MA, Ul-Hamid A, Chong KK

Microsc Res Tech, 2024 May;87(5):957-976.
PMID: 38174385 DOI: 10.1002/jemt.24487

The present exploration demonstrates the efficient, sustainable, cost-effective, and environment-friendly green approach for the synthesis of silver (Ag)-doped copper oxide (CuO) embedded with reduced graphene oxide (rGO) nanocomposite using the green one-pot method and the green deposition method. Leaf extracts of Ficus carica and Azadirachta indica were used for both methods as reducing and capping agents. The effect of methodology and plant extract was analyzed through different characterization techniques such as UV-visible spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), x-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM). The lowest band gap of 3.0 eV was observed for the Ag/CuO/rGO prepared by the green one-pot method using F. carica. The reduction of graphene oxide (GO) and the formation of metal oxide was confirmed through functional group detection using FT-IR. Calculation of thermodynamic parameters showed that all reactions involved were nonspontaneous and endothermic which shows the stability of nanocomposites. XRD studies revealed the crystallinity, phase purity and small average crystallite size of 32.67 nm. SEM images disclosed that the morphology of the nanocomposites was spherical with agglomeration and rough texture. The particle size of the nanocomposites calculated through HRTEM was found in agreement with the XRD results. The numerous properties of the synthesized nanocomposites enhanced their potential against the degradation of methylene blue, rhodamine B, and ciprofloxacin. The highest percentage degradation of Ag/CuO/rGO was found to be 97%, synthesized using the green one-pot method with F. carica against ciprofloxacin, which might be due to the lowest band gap, delayed electron-hole pair recombination, and large surface area available. The nanocomposites were also tested against the Gram-positive and Gram-negative bacteria. RESEARCH HIGHLIGHTS: Facile synthesis of Ag/CuO/rGO nanocomposite using a green one-pot method and the green deposition method. The lowest band gap of 3.0 eV was observed for nanocomposite prepared by a green one-pot method using Ficus carica. Least average crystallite size of 32.67 nm was found for nanocomposite prepared by a green one-pot method using F. carica. Highest antibacterial and catalytic activity (97%) was obtained against ciprofloxacin with nanocomposite prepared through green one-pot method using F. carica. A mechanism of green synthesis is proposed.

Matched MeSH terms: Gram-Negative Bacteria

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