Metabolomics responses and tolerance of Pseudomonas aeruginosa under acoustic vibration stress.

Sound has been shown to impact microbial behaviors. However, our understanding of the chemical and molecular mechanisms underlying these microbial responses to acoustic vibration is limited. In this study, we used untargeted metabolomics analysis to investigate the effects of 100-Hz acoustic vibration on the intra- and extracellular hydrophobic metabolites of P.

Microtiter plate with built-in oxygen sensors: a novel approach to investigate the dynamics of Pseudomonas aeruginosa growth suppression in the presence of divalent cations and antibiotics.

The depletion of dissolved oxygen in a defined synthetic medium can be measured in real time, using a micro-well plate format, associated with a fluorescent plate reader. This technology is appropriate for investigating the effect of antibiotics on cell kinetics because there is a direct correlation between the latter and the amount of dissolved oxygen in the medium of an assay. In this study, the metabolic activity of the opportunistic human pathogen Pseudomonas aeruginosa PA01 was investigated using the OxoPlate OP96U optical sensor technology.

Persister cells: formation, resuscitation and combative therapies.

Persister cells, or superfits, have been strongly implicated in the recalcitrance and recurrence of chronic bacterial infection through the dormant (metabolically reduced) phenotype they display and the tolerance to antimicrobial agents this dormancy grants them. The complex biochemical events that lead to the formation of persister cells are not completely understood, though much research has linked the degradation of type II toxin/antitoxin systems and reduced cellular ATP levels to the rise in stress response molecules (where (p)ppGpp is of particular interest), which induce this dormant state. The equally complex mechanism of resuscitation is initiated by the cells' ability to sense nutrient availability via chemotaxis systems.

A novel air-dried multiplex high-resolution melt assay for the detection of extended-spectrum β-lactamase and carbapenemase genes.

Objectives: This study aimed to develop and evaluate a novel air-dried high-resolution melt (HRM) assay to detect eight major extended-spectrum β-lactamase (ESBL) (bla and bla groups 1 and 9) and carbapenemase (bla, bla, bla, bla and bla) genes that confer resistance to cephalosporins and carbapenems.

Methods: The assay was evaluated using 439 DNA samples extracted from bacterial isolates from Nepal, Malawi and the UK and 390 clinical isolates from Nepal with known antimicrobial susceptibility. Assay reproducibility was evaluated across five different real-time quantitative PCR (qPCR) instruments [Rotor-Gene® Q, QuantStudio 5, CFX96, LightCycler® 480 and Magnetic Induction Cycler (Mic)].

Nitro-Carba test, a novel and simple chromogenic phenotypic method for rapid screening of carbapenemase-producing Enterobacteriaceae.

Objectives: In this study, a rapid and simple chromogenic method for screening of carbapenemase-producing Enterobacteriaceae (CPE), namely the Nitro-Carba test (NCT), was developed.

Methods: The NCT was validated using a total of 31 carbapenemase-producing isolates [9 Klebsiella pneumoniae carbapenemase (KPC), 11 metallo-β-lactamase (MBL) and 11 OXA-48] and 56 non-carbapenemase-producing isolates. The assay relies on the hydrolysis of nitrocefin by carbapenemases in the presence of carbapenem antibiotics.

Field-based detection of biological samples for forensic analysis: Established techniques, novel tools, and future innovations.

Field based forensic tests commonly provide information on the presence and identity of biological stains and can also support the identification of species. Such information can support downstream processing of forensic samples and generate rapid intelligence. These approaches have traditionally used chemical and immunological techniques to elicit the result but some are known to suffer from a lack of specificity and sensitivity.

A nitrocefin disc supplemented with ertapenem for rapid screening of carbapenemase-producing Enterobacteriaceae.

Reliable, simple and rapid methods for laboratory detection of carbapenemases are important for an appropriate antibiotic administration. A nitrocefin disc containing ertapenem for rapid screening of carbapenemase production among Enterobacteriaceae is developed in the present study. A total of 87 molecularly-confirmed Enterobacteriaceae including 31 carbapenemase producers and 56 non-carbapenemase producers, were tested with nitrocefin discs supplemented with and without ertapenem (20 μg/disc).

Speciation of common Gram-negative pathogens using a highly multiplexed high resolution melt curve assay.

The identification of the bacterial species responsible for an infection remains an important step for the selection of antimicrobial therapy. Gram-negative bacteria are an important source of hospital and community acquired infections and frequently antimicrobial resistant. Speciation of bacteria is typically carried out by biochemical profiling of organisms isolated from clinical specimens, which is time consuming and delays the initiation of tailored treatment.

Boesenbergia rotunda (L.) Mansf. extract potentiates the antibacterial activity of some β-lactams against β-lactam-resistant staphylococci.

Objectives: The purpose of this study was to investigate the effect of Boesenbergia rotunda (L.) Mansf. extract (BRE) and peptidoglycan inhibitor antibiotics, alone and in combination, against β-lactam-resistant staphylococci.

Evaluation of resazurin microtiter plate assay and HPLC- photodiode array analysis of the roots of Asparagus adscendens.

Asparagus adscendens Roxb. (Asparagaceae), is native to the Himalayas. The present study, for the first time, was undertaken to explore the antimicrobial potential, to determine the minimum inhibitory concentration (MIC) values of the methanol extract of the roots of A.

The performance of a resazurin chromogenic agar plate with a combined disc method for rapid screening of extended-spectrum-β-lactamases, AmpC β-lactamases and co-β-lactamases in Enterobacteriaceae.

A promising means of rapid screening of extended-spectrum-β-lactamase (ESBL), AmpC β-lactamase, and co-production of ESBL and AmpC that combines resazurin chromogenic agar (RCA) with a combined disc method is here reported. Cefpodoxime (CPD) discs with and without clavulanic acid (CA), cloxacillin (CX) and CA+CX were evaluated against 86 molecularly confirmed β-lactamase-producing Enterobacteriaceae, including 15 ESBLs, 32 AmpCs, nine co-producers of ESBL and AmpC and 30 carbapenemase producers. The CA and CX synergy test successfully detected all ESBL producers (100% sensitivity and 98.

A demonstration of athermal effects of continuous microwave irradiation on the growth and antibiotic sensitivity of Pseudomonas aeruginosa PAO1.

Stress, caused by exposure to microwaves (2.45 GHz) at constant temperature (37 ± 0.5°C), alters the growth profile of Pseudomonas aeruginosa PAO1.

Synergism and the mechanism of action of the combination of α-mangostin isolated from Garcinia mangostana L. and oxacillin against an oxacillin-resistant Staphylococcus saprophyticus.

Background: Globally, staphylococci have developed resistance to many antibiotics. New approaches to chemotherapy are needed and one such approach could be to use plant derived actives with conventional antibiotics in a synergestic way. The purpose of this study was to isolate α-mangostin from the mangosteen (Garcinia mangostana L.

Phenotypic detection of AmpC β-lactamases, extended-spectrum β-lactamases and metallo-β-lactamases in Enterobacteriaceae using a resazurin microtitre assay with inhibitor-based methods.

Dissemination of antibiotic resistance in Enterobacteriaceae mediated by AmpC β-lactamase, extended-spectrum β-lactamase (ESBL) and metallo-β-lactamase (MBL) is clinically significant. A simple and relatively quick method for the detection of these resistance phenotypes would greatly improve chemotherapeutic recommendation. This technology would provide valuable input in our surveillance of resistance on a global stage, particularly if the methodology could be applicable to resource-poor settings.

Acoustic vibration can enhance bacterial biofilm formation.

This paper explores the use of low-frequency-low-amplitude acoustic vibration on biofilm formation. Biofilm development is thought to be governed by a diverse range of environmental signals and much effort has gone into researching the effects of environmental factors including; nutrient availability, pH and temperature on the growth of biofilms. Many biofilm-forming organisms have evolved to thrive in mechanically challenging environments, for example soil yet, the effects of the physical environment on biofilm formation has been largely ignored.

Loop-mediated isothermal amplification (LAMP) for the rapid detection of Mycoplasma genitalium.

Mycoplasma genitalium is a sexually transmissible, pathogenic bacterium and a significant cause of nongonococcal urethritis in both men and women. Due to the difficulty of the culture of M. genitalium from clinical samples, the laboratory diagnosis of M.

Trichomonas vaginalis: Clinical relevance, pathogenicity and diagnosis.

Trichomonas vaginalis is the etiological agent of trichomoniasis, the most prevalent non-viral sexually transmitted disease worldwide. Trichomoniasis is a widespread, global health concern and occurring at an increasing rate. Infections of the female genital tract can cause a range of symptoms, including vaginitis and cervicitis, while infections in males are generally asymptomatic.

Loop-mediated isothermal amplification test for detection of Neisseria gonorrhoeae in urine samples and tolerance of the assay to the presence of urea.

A loop-mediated isothermal amplification (LAMP) assay for open reading frame 1 (ORF1) of the glutamine synthetase gene of Neisseria gonorrhoeae was able to tolerate urea concentrations of ≤ 1.8 M, compared with a PCR assay that was functional at concentrations of <100 mM. The LAMP assay was as sensitive as the PCR assay while being faster and simpler to perform.

Incorporation of L-lysine and 2,2'-dipyridyl in the growth media promotes desferrioxamine E production by an actinobacterium.

The study describes the use of the chelating agent 2,2'-dipyridyl in conjunction with lysine to increase the production of the siderophore desferrioxamine E by a previously described actinobacterium 23F. Desferrioxamine E is a type of siderophore known to be produced by Streptomycete species. Lysine is a precursor of the siderophore and its presence in the culture medium is known to promote desferrioxamine E synthesis.

A new approach to studying ion uptake by actinomycetes.

A streptomycete that had the ability to avidly sequester iron via siderophores was previously isolated from environmental soil samples. The chelating agent expressed by this organism is confirmed by HPLC as desferrioxamine E. Although the traditional chromo azuerol sulphate (CAS) assay for detection of siderophores is based upon the chelation of iron we were interested to examine the relationship of these iron-capturing molecules with other ions.

Isolation and identification of mucinolytic actinomycetes.

Biochemical and physiological tests, and 16S rRNA gene sequences, were used to classify nine Actinomycete strains isolated from soil and sand samples in Thailand. These strains were isolated based on their ability to readily degrade mucin glycoproteins. A turbidometric based mucinolytic assay was developed to confirm this.

Encapsulation and release of alpha-chymotrypsin from poly(glycerol adipate-co-omega-pentadecalactone) microparticles.

Polymer-based microparticles are increasingly becoming of interest for a variety of applications including drug delivery. Recently poly(glycerol adipate) (PGA) and poly(glycol adipate-co-omega-pentadecalactone) have shown promise for delivery of dexamethasone phosphate and ibuprofen. In this paper the copolyester poly(glycol adipate-co-omega-pentadecalactone) was evaluated as a colloidal delivery system for encapsulated therapeutic proteins.

Application of Toxocara canis excretory-secretory antigens and IgG subclass antibodies (IgG1-4) in serodiagnostic assays of human toxocariasis.

A major problem in the serodiagnosis of human toxocariasis in tropical countries is cross-reaction with antibodies to other helminthic diseases and a lack of sensitivity. The majority of tests currently available use total IgG and, in this study, the use of peroxidase-conjugated anti-human IgG subclass antibodies (IgG1-4) was compared with total IgG for the diagnosis of human toxocariasis by using Toxocara excretory-secretory (TES) antigens in an enzyme-linked immunosorbent assay (ELISA) format. All four IgG subclass antibodies gave approximately 10-fold increases in optical density (OD) values for 50 toxocariasis patients compared to 29 healthy normals; this was significantly greater than the approximate doubling of OD values seen in the total IgG-ELISA format.

Differentiation and protease production in Micromonospora echinospora (ATCC 15837).

Micromonospora echinospora differentiates in both submerged and surface cultures producing abundant dark spores after a period of vegetative mycelial growth. In submerged batch cultures, under either carbon or nitrogen limiting conditions, protease activity was found to coincide with sporulation indicating a relationship between proteolytic activity and differentiation in this organism. Further evidence for this link was provided from surface grown cultures wherein sporulation was inhibited by the serine protease inhibitors TLCK and TPCK.

Continuous culture--making a comeback?

The heyday of continuous culture was in the 1960s, when its versatility and reproducibility were used to address fundamental problems in diverse microbiological fields such as biochemistry, ecology, genetics and physiology. The advent of molecular genetics in the 1970s and 1980s led to a decline in the popularity of continuous culture as a standard laboratory tool. The current trend of studying global proteomics, transcriptomics and metabolomics requires reproducible, reliable and biologically homogeneous datasets with which to approach a given problem.