Susceptibility of Gram-negative bacteria to the synergistic bactericidal action of serum and polymyxin B nonapeptide

Polymyxin B nonapeptide was able to sensitize Escherichia coli strains and strains of Salmonella typhimurium, Klebsiella spp., Enterobacter cloacae, Pseudomonas aeruginosa, and Haemophilus influenzae to the bactericidal action of fresh normal human serum. The degree of sensitization varied significantly within the strains. Strains of Proteus mirabilis, Neisseria gonorrhoeae, and N. meningitidis remained resistant.

Download Full-text

Enhancement of photobactericidal activity of chlorin-e6-cellulose nanocrystals by covalent attachment of polymyxin B

Journal of Materials Chemistry B ◽

10.1039/c7tb01274h ◽

2017 ◽

Vol 5 (33) ◽

pp. 6953-6962 ◽

Cited By ~ 13

Author(s):

Florent Le Guern ◽

Tan-Sothea Ouk ◽

Karine Grenier ◽

Nicolas Joly ◽

Vincent Lequart ◽

...

Keyword(s):

Escherichia Coli ◽

Staphylococcus Aureus ◽

Pseudomonas Aeruginosa ◽

Staphylococcus Epidermidis ◽

Polymyxin B ◽

Chlorin E6 ◽

Covalent Attachment ◽

Gram Negative Bacteria ◽

Gram Negative ◽

Gram Positive Bacteria

Following light irradiation, a new nanomaterial, elaborated from CNCs, chlorin-e6 and polymyxin B, demonstrated efficiency against Gram-negative bacteria (Escherichia coli,Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus,Staphylococcus epidermidis).

Download Full-text

Indole and (E)-2-hexenal, phytochemical potentiators of polymyxins against Pseudomonas aeruginosa and Escherichia coli.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.40.6.1438 ◽

1996 ◽

Vol 40 (6) ◽

pp. 1438-1441 ◽

Cited By ~ 11

Author(s):

A Kubo ◽

C S Lunde ◽

I Kubo

Keyword(s):

Escherichia Coli ◽

Pseudomonas Aeruginosa ◽

Antimicrobial Activity ◽

Biological Activity ◽

Fold Increase ◽

Polymyxin B ◽

Gram Negative Bacteria ◽

Gram Negative ◽

Potential Efficacy ◽

Colistin Methanesulfonate

Combinations of polymyxins and phytochemicals were tested for antimicrobial activity against two gram-negative bacteria. Various degrees of potentiation were found against Pseudomonas aeruginosa and Escherichia coli with (E)-2-hexenal and indole. Three-compound combinations were found to further increase the activity of polymyxin B sulfate and colistin methanesulfonate against both bacteria. Combinations with colistin against P. aeruginosa resulted in the highest degree of potentiation, with a 512-fold increase in colistin antimicrobial activity. These results indicate the potential efficacy of phytochemical combinations with antibiotics to enhance total biological activity.

Download Full-text

MexAB-OprM Efflux Pump Interaction with the Peptidoglycan of Escherichia coli and Pseudomonas aeruginosa

International Journal of Molecular Sciences ◽

10.3390/ijms22105328 ◽

2021 ◽

Vol 22 (10) ◽

pp. 5328

Author(s):

Miao Ma ◽

Margaux Lustig ◽

Michèle Salem ◽

Dominique Mengin-Lecreulx ◽

Gilles Phan ◽

...

Keyword(s):

Escherichia Coli ◽

Pseudomonas Aeruginosa ◽

Cell Division ◽

Membrane Proteins ◽

Outer Membrane ◽

Efflux Pump ◽

Gram Negative Bacteria ◽

Gram Negative ◽

Active Efflux

One of the major families of membrane proteins found in prokaryote genome corresponds to the transporters. Among them, the resistance-nodulation-cell division (RND) transporters are highly studied, as being responsible for one of the most problematic mechanisms used by bacteria to resist to antibiotics, i.e., the active efflux of drugs. In Gram-negative bacteria, these proteins are inserted in the inner membrane and form a tripartite assembly with an outer membrane factor and a periplasmic linker in order to cross the two membranes to expulse molecules outside of the cell. A lot of information has been collected to understand the functional mechanism of these pumps, especially with AcrAB-TolC from Escherichia coli, but one missing piece from all the suggested models is the role of peptidoglycan in the assembly. Here, by pull-down experiments with purified peptidoglycans, we precise the MexAB-OprM interaction with the peptidoglycan from Escherichia coli and Pseudomonas aeruginosa, highlighting a role of the peptidoglycan in stabilizing the MexA-OprM complex and also differences between the two Gram-negative bacteria peptidoglycans.

Download Full-text

Pyelonephritis in Pediatric Uropathic Patients: Differences from Community-Acquired Ones and Therapeutic Protocol Considerations. A 10-Year Single-Center Retrospective Study

Children ◽

10.3390/children8060436 ◽

2021 ◽

Vol 8 (6) ◽

pp. 436

Author(s):

Giovanni Parente ◽

Tommaso Gargano ◽

Stefania Pavia ◽

Chiara Cordola ◽

Marzia Vastano ◽

...

Keyword(s):

Escherichia Coli ◽

Retrospective Study ◽

Success Rate ◽

Pediatric Population ◽

Gram Negative Bacteria ◽

Gram Positive ◽

Gram Negative ◽

Gram Positive Bacteria ◽

Significant Difference ◽

Klebsiella Spp

Pyelonephritis (PN) represents an important cause of morbidity in the pediatric population, especially in uropathic patients. The aim of the study is to demonstrate differences between PNs of uropathic patients and PNs acquired in community in terms of uropathogens involved and antibiotic sensitivity; moreover, to identify a proper empiric therapeutic strategy. A retrospective study was conducted on antibiograms on urine cultures from PNs in vesicoureteral reflux (VUR) patients admitted to pediatric surgery department and from PNs in not VUR patients admitted to Pediatric Emergency Unit between 2010 and 2020. We recorded 58 PNs in 33 patients affected by VUR and 112 PNs in the not VUR group. The mean age of not VUR patients at the PN episode was 1.3 ± 2.6 years (range: 20 days of life–3 years), and almost all the urine cultures, 111 (99.1%), isolated Gram-negative bacteria and rarely, 1 (0.9%), Gram-positive bacteria. The Gram-negative uropathogens isolated were Escherichia coli (97%), Proteus mirabilis (2%), and Klebsiella spp. (1%). The only Gram-positive bacteria isolated was an Enterococcus faecalis. As regards the antibiograms, 96% of not VUR PNs responded to beta-lactams, 99% to aminoglycosides, and 80% to sulfonamides. For the VUR group, mean age was 3.0 years ± 3.0 years (range: 9 days of life–11 years) and mean number of episodes per patient was 2.0 ± 1.0 (range: 1–5); 83% of PNs were by Gram-negatives bacteria vs. 17% by Gram-positive: the most important Gram-negative bacteria were Pseudomonas aeruginosa (44%), Escherichia coli (27%), and Klebsiella spp. (12%), while Enterococcus spp. determined 90% of Gram-positive UTIs. Regimen ampicillin/ceftazidime (success rate: 72.0%) was compared to ampicillin/amikacin (success rate of 83.0%): no statistically significant difference was found (p = 0.09). The pathogens of PNs in uropathic patients are different from those of community-acquired PNs, and clinicians should be aware of their peculiar antibiotic susceptibility. An empiric therapy based on the association ampicillin + ceftazidime is therefore suggested.

Download Full-text

Emergence of Colistin Resistant Gram-Negative Bacteria in a Tertiary Care Rural Hospital in 2019

KYAMC Journal ◽

10.3329/kyamcj.v11i2.48421 ◽

2020 ◽

Vol 11 (2) ◽

pp. 87-90

Author(s):

Abdullah Akhtar Ahmed ◽

Nusrat Akhtar Juyee ◽

SM Ali Hasan

Keyword(s):

Escherichia Coli ◽

Pseudomonas Aeruginosa ◽

Tertiary Care ◽

Salmonella Typhi ◽

Rural Hospital ◽

Gram Negative Bacteria ◽

Bacterial Isolates ◽

Colistin Resistance ◽

Sensitivity Testing ◽

Gram Negative

Background: Colistin-resistant Gram-negative bacteria is a rapidly emerging global threatgenerated a sense of public alarm. Objective: To combat this challenge a study was designedto evaluate the fast spreading infections by colistin-resistant pathogens in the tertiary care rural hospital of Bangladesh. Materials and Methods: To study isolation ofpathogenic gram-negative bacilli,clinical sample (n-640) of hospitalized patients of Khwaja Yunus Ali Medical College Hospital in Enayetpur, Bangladesh during the 1st quarter of the year 2019 were used. The bacterial isolates were screened for meropenem and colistin-resistance. Results: A total of 156 bacterial isolates were studied which included Escherichia coli (n-112), Klebsiella pneumoniae (n-14), Pseudomonas aeruginosa (n-27), and Salmonella typhi (n-3). Antibiotic sensitivity testing showed that 32/156(20%) and 119/156 (76%) isolates were resistant to meropenem and colistin, respectively. whereas 50/156 (32%) isolates were resistant to both antibiotics. Escherichia coli, K. pneumoniae, pseudomonas aeruginosa, and Salmonella typhi isolates respectivelywere 112/156 (72%), 14/156 (9%). 27/156 (17%), and 3/156 (2%). Conclusion: Colistin is typically used as salvage therapy, or last-line treatment, for MDR gramnegative infections.But there is worrisome therapeutic scenario in our study finding of colistin resistance is 76% in Gram-negative bacteria of the clinical isolates. The restricted and rational use of colistin drug is the need of hour. KYAMC Journal Vol. 11, No.-2, July 2020, Page 87-90

Download Full-text

National Surveillance of Antimicrobial Susceptibility of Bacteremic Gram-Negative Bacteria with Emphasis on Community-Acquired Resistant Isolates: Report from the 2019 Surveillance of Multicenter Antimicrobial Resistance in Taiwan (SMART)

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01089-20 ◽

2020 ◽

Vol 64 (10) ◽

Author(s):

Po-Yu Liu ◽

Yu-Lin Lee ◽

Min-Chi Lu ◽

Pei-Lan Shao ◽

Po-Liang Lu ◽

...

Keyword(s):

Escherichia Coli ◽

Pseudomonas Aeruginosa ◽

Antimicrobial Resistance ◽

Klebsiella Pneumoniae ◽

Gram Negative Bacteria ◽

National Surveillance ◽

Gram Negative ◽

Content Type ◽

E Coli ◽

Carbapenem Resistant

ABSTRACT A multicenter collection of bacteremic isolates of Escherichia coli (n = 423), Klebsiella pneumoniae (n = 372), Pseudomonas aeruginosa (n = 300), and Acinetobacter baumannii complex (n = 199) was analyzed for susceptibility. Xpert Carba-R assay and sequencing for mcr genes were performed for carbapenem- or colistin-resistant isolates. Nineteen (67.8%) carbapenem-resistant K. pneumoniae (n = 28) and one (20%) carbapenem-resistant E. coli (n = 5) isolate harbored blaKPC (n = 17), blaOXA-48 (n = 2), and blaVIM (n = 1) genes.

Download Full-text

Polymyxin B–modified upconversion nanoparticles for selective detection of Gram-negative bacteria such as Escherichia coli

Journal of Chemical Research ◽

10.1177/1747519820911266 ◽

2020 ◽

Vol 44 (11-12) ◽

pp. 756-761

Author(s):

Yan Qiao ◽

Hongchao Geng ◽

Ning Jiang ◽

Xingqi Zhu ◽

Chenyi Li ◽

...

Keyword(s):

Escherichia Coli ◽

Limit Of Detection ◽

Polymyxin B ◽

Upconversion Nanoparticles ◽

Selective Detection ◽

Gram Negative Bacteria ◽

Cationic Antimicrobial Peptide ◽

Gram Negative ◽

In Vivo Fluorescence Imaging

Upconversion nanoparticles, Yb,Tm,Fe-doped NaYF4 nanoparticles, are synthesized and modified with polymyxin B for the selective detection of Gram-negative bacteria. Polymyxin B, a cyclic cationic antimicrobial peptide which can specifically bind to the lipopolysaccharides of cell wall of Gram-negative bacteria, such as Escherichia coli, is used to target and bind Gram-negative bacteria. The bacteria are then quantified by measuring the fluorescence intensity of the upconversion nanoparticle–bacteria complexes at 801 nm under 980 nm excitation. A limit of detection of 36 CFU/mL is achieved in the detection of Escherichia coli, and Escherichia coli in soybean milk is successfully detected. The limited autofluorescence and photobleaching properties of the upconversion nanoparticles make the proposed method useful for in vivo fluorescence imaging of Gram-negative bacteria.

Download Full-text

In VitroSusceptibility of Characterized β-Lactamase-Producing Strains Tested with Avibactam Combinations

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.04191-14 ◽

2014 ◽

Vol 59 (3) ◽

pp. 1789-1793 ◽

Cited By ~ 75

Author(s):

Henry Li ◽

Mark Estabrook ◽

George A. Jacoby ◽

Wright W. Nichols ◽

Raymond T. Testa ◽

...

Keyword(s):

Escherichia Coli ◽

Pseudomonas Aeruginosa ◽

Broad Spectrum ◽

Enterobacter Cloacae ◽

Gram Negative ◽

Content Type ◽

Extended Spectrum ◽

Lactamase Inhibitor

ABSTRACTAvibactam, a broad-spectrum β-lactamase inhibitor, was tested with ceftazidime, ceftaroline, or aztreonam against 57 well-characterized Gram-negative strains producing β-lactamases from all molecular classes. Most strains were nonsusceptible to the β-lactams alone. Against AmpC-, extended-spectrum β-lactamase (ESBL)-, and KPC-producingEnterobacteriaceaeorPseudomonas aeruginosa, avibactam lowered ceftazidime, ceftaroline, or aztreonam MICs up to 2,048-fold, to ≤4 μg/ml. Aztreonam-avibactam MICs against a VIM-1 metallo-β-lactamase-producingEnterobacter cloacaeand a VIM-1/KPC-3-producingEscherichia coliisolate were 0.12 and 8 μg/ml, respectively.

Download Full-text

Gram Negative Bacteria (GNB) Isolated From Used Home-made and Surgical Nose/Face Mask by Local Residents of Akungba Akoko, Ondo State, a Threat to Life and False Sense of Protection against SARS-CoV-2 (COVID-19)

Asian Journal of Advanced Research and Reports ◽

10.9734/ajarr/2021/v15i1030428 ◽

2021 ◽

pp. 1-17

Author(s):

Oludare Temitope Osuntokun

Keyword(s):

Escherichia Coli ◽

Pseudomonas Aeruginosa ◽

Proteus Mirabilis ◽

Antimicrobial Agents ◽

Face Mask ◽

Gram Negative Bacteria ◽

Haemophilus Influenza ◽

Gram Negative ◽

False Sense ◽

Zones Of Inhibition

Nose/Face masks are physical barriers to respiratory droplets that may enter through the nose and mouth to cause infections in the respiratory tract. The study was determined and assess the presence of Gram-negative bacteria in used home-made and surgical nose mask by residents of Akungba-Akoko Ondo State and to determine the antimicrobial susceptibility and resistant profile of the isolated bacteria to eight (8) different antimicrobial agents. The antimicrobial analysis were performed using standard microbiological and biochemical methods. Antimicrobial Susceptibility test of all identified isolates to antimicrobial agents were determined using the standard Kirby-Bauer disk diffusion method. The Gram-negative bacteria that were detected from the used home-made and surgical nose mask in this study include: Haemophilus influenza, Proteus mirabilis, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumonia. During this study, all the Gram-negative bacteria isolates were resistant to Ciproflox in both used home-made and surgical nose mask. All isolates were also resistant to Ampicilin, Augmentin, Septrin and Streptomycin. In this study, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa were isolated organism from used home-made nose mask, it was observed that Escherichia coli were resistant to Augmentin, Tarivid, Ciproflox, Gentamycin, and Reflaxine, and Pseudomonas aeruginosa were resistant to Tarivid, Ciproflox, and Nalidixic acid between 20 mm and 24 mm zones of inhibition respectively. Haemophilus influenza, Pseudomonas aeruginosa, Escherichia coli and Proteus mirabilis were isolated organism from used surgical nose mask. It was observed that all isolated organisms from the used surgical nose/face mask were resistant to Augmentin and Gentamycin between 20 and 24 mm zones of inhibition respectively. Klebsiella pneumoniae were isolated from both used home-made and surgical nose/face mask and were found to be resistant to Streptomycin, Septrin, Ampicilin, and Gentamicin between 20 to 22 mm zones of inhibition respectively. Proteus mirabilis were isolated from used surgical nose/face mask, they were found to be resistant to Ciproflox at 21mm zones of inhibition. Haemophilus influenza were resistant to Ampicilin, Septrin, Streptomycin, and Augmentin at 23 mm zones of inhibition. Isolates from used both home-made and surgical nose/face mask were subjected to modified and synergized antibiotics, it was observed that the isolates from both used home-made and surgical nose mask were resistant to all modified and synergized antibiotics between 20 and 25 mm zones of inhibition respectively. The result of this study validates the potency of Gram negative bacteria isolated from used both home-made and surgical nose/face mask and the degree of invasion and evasiveness, thereby causing various degrees of infections and a false sense of protection against SARS-CoV-2 (COVID-19). Finding from this research recommends a stringent measures were needed to be implemented, to halt and combat this revenging situation especially in the new era of mutating SARS-CoV-2 Virus not only in Nigeria, worldwide at large.

Download Full-text

Green Synthesis of Silver Nanoparticles Using Novel Launaea Procumbens Leaves Extract and Screening Its Antibacterial Activity

10.21203/rs.3.rs-1049725/v1 ◽

2021 ◽

Author(s):

Sanjay Ratan Kumavat ◽

SATYENDRA MISHRA

Keyword(s):

Escherichia Coli ◽

Staphylococcus Aureus ◽

Pseudomonas Aeruginosa ◽

Silver Nanoparticles ◽

Green Synthesis ◽

Gram Negative Bacteria ◽

Zone Of Inhibition ◽

Gram Negative ◽

Green Synthesized Silver Nanoparticles ◽

Launaea Procumbens

Abstract Plants are emerging as a cost-effective and ecofriendly method for green synthesis of nanoparticles. The plant extract Launaea procumbens was used as a reduction agent in the green synthesis of silver nanoparticles. UV-Visible spectroscopy, HR-TEM, SAED, FE-SEM, EDAX, DLS, and FT-IR were used to study the green synthesized silver nanoparticles. UV-Vis spectroscopy of a prepared silver solution revealed maximum absorption at 435 nm. The synthesized silver nanoparticles were found to be spherical in shape with a size in the range of 24.28 to 31.54 nm. DLS analysis was used to determine the size of the green synthesized silver nanoparticles, which showed outstanding antibacterial action against Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus, as well as Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa. Gram-positive Bacillus subtilis had a maximum zone of inhibition of 20 mm, Staphylococcus aureus had a zone of inhibition of 19 mm, and Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa had zones of inhibition of 13 mm.

Download Full-text