Cations reduce antimicrobial efficacy of lysozyme-chelator combinations

Reduction of the antimicrobial efficacy of lysozyme-chelator combinations against two Escherichia coli O157:H7 strains on addition of mineral salts was studied. The objective of the study was to determine the effect of type and concentration of mono-, di-, and trivalent mineral salts on the antimicrobial effectiveness of lysozyme and various chelators against E. coli O157:H7. Seven salts (Al3+, Ca2+, Fe2+, Fe3+, K+, Mg2+, and Na+) at 1 to 10 mM were added to aqueous solutions of lysozyme and disodium ethylenediamine tetraacetic acid (EDTA), disodium pyrophosphate (DSPP), or pentasodium tripolyphosphate (PSTPP) at pH 6, 7, or 8 and applied to cultures of E. coli O157:H7 strains 932 and H1730. Inhibitory activity of lysozyme chelator combinations against both strains was completely lost after addition of > or = 1 mM Ca2+ and Mg2+ at pH 7 and 8. At pH 6, antimicrobial activity of lysozyme-EDTA against both strains was retained in the presence of calcium or magnesium cations. DSPP-lysozyme inhibited strain H1730 at pH 6 despite the presence of Mg2+. Concentrations above 4 mM Fe2+ neutralized activity of all lysozyme-chelator combinations. Reversal of inhibition by lysozyme-chelator complexes by the monovalent Na+ and K+ ions depended on E. coli O157:H7 strain type. Neither monovalent cation reversed inhibition of strain 932. However, Na+ and K+ reversed lysozyme-chelator inhibition of strain H1730. The addition of > or = 1 mM Fe3+ or Al3+ was effective in reversing inhibition of both strains by lysozyme and EDTA at pH 6, 7, and 8. Isothermal titration calorimetry was used to determine the amount of ion-specific competitive binding of free cations by EDTA-lysozyme combinations. A mechanistic model for the antimicrobial functionality of chelator-lysozyme combinations is proposed.

Antimicrobial activity of ultrasound-assisted solvent-extracted spices

AIMS

The objective of this research was to determine the antimicrobial activity of conventional and high-intensity ultrasound-assisted (HI-US) solvent-extracted Thai spices, including ginger (Zingiber officinale Rose), fingerroot (Bosenbergia pandurata Holtt) and turmeric (Curouma longa Linn).

METHODS AND RESULTS

Extracts were obtained using hexane, isopropanol and a 7 : 3 isopropanol : hexane mixture as solvents with and without HI-US. The antimicrobial activity of the extracts was assayed against four strains each of Listeria monocytogenes and Salmonella Typhimurium DT 104 using an agar dilution assay. Application of HI-US did not alter antibacterial activity against S. Typhimurium, but antilisterial activity of some HI-US spice extracts decreased. Solvent type affected antimicrobial efficacy of extracts with hexane producing the least antimicrobial activity. Fingerroot extracted with isopropanol-hexane and without HI-US had the best antilisterial effect while HI-US-isopropanol fingerroot extract had the greatest antimicrobial efficacy against S. Typhimurium.

CONCLUSIONS

Application of HI-US reduced time of extraction to 5 min, compared with the 24 h required for conventional extraction and maintained antimicrobial activity against Salmonella but slightly reduced activity against Listeria.

SIGNIFICANCE AND IMPACT OF THE STUDY

HI-US in combination with proper solvent selection may offer a new tool to optimize extraction of spice essential oil for use as antimicrobial agents, and reduce processing time and costs.

Enhanced inhibition of Escherichia coli O157:H7 by lysozyme and chelators

This study examined the effects of three chelating agents (EDTA, disodium pyrophosphate [DSPP], and pentasodium tripolyphosphate [PSTPP]) on the inhibition of the growth of Escherichia coli O157:H7 by lysozyme. The objective of this study was to identify replacement chelators that exhibit synergistic properties similar to those of EDTA. The inhibitory effects of EDTA at 300 to 1,500 microg/ml and of DSPP and PSTPP at 3,000 to 15,000 microg/ml in combination with lysozyme at 200 to 600 microg/ml for up to 48 h at pHs of 6.0, 7.0, and 8.0 on four strains of E. coli O157:H7 was studied with the use of a microbroth dilution assay. The addition of EDTA enhanced lysozyme's inhibitory effect on strains of E. coli O157:H7. EDTA at > or = 300 microg/ml combined with lysozyme at 200 to 600 microg/ml was sufficient to inhibit the growth of the strains at pHs of 6.0 and 8.0. At pH 7.0, lysozyme at 200 to 600 microg/ml and EDTA concentrations of > or = 1,000 microg/ml were effective in inhibiting three of the four strains. DSPP at pH 6.0 was inhibitory at > or = 10,000 microg/ml when combined with lysozyme at 200 to 300 microg/ml. In contrast, PSTPP increased the inhibitory activity of lysozyme more effectively at pH 8.0. Lysozyme at 200 to 600 microg/ml was effective against two strains of E. coli O157:H7 when used in conjunction with PSTPP at > or = 5,000 microg/ml. The remaining strains were inhibited by PSTPP at > or = 10,000 microg/ml. Our results indicate that inhibition occurred with each lysozyme-chelator combination, but the concentrations of phosphates required to increase the antimicrobial spectrum of lysozyme against E. coli O157:H7 were higher than the EDTA concentrations required to achieve the same effect.

Direct decays from superdeformed states in 192Pb observed using time-correlated gamma-ray spectroscopy

Correlations of decays above and below isomeric states in the normally deformed minimum of 192Pb have been used to identify discrete transitions in the decay of the superdeformed (SD) band. The data establish the absolute excitation energy of the lowest observed SD level as 4.425 MeV. Extrapolation to the bandhead indicates that the excitation energy of the superdeformed well in 192Pb is 0.5 MeV lower than in the heavier isotope 194Pb. The results confirm the trend to decreasing excitation energy with decreasing neutron number predicted by both a macroscopic Strutinsky method approach and microscopic mean field calculations.

Growth of Escherichia coli O157:H7, Salmonella typhimurium DT104, and Listeria monocytogenes in dark cutting beef at 10 or 22 degrees C

An experiment was conducted to determine the effects of the dark, firm, and dry (DFD) condition of beef on growth of the foodborne pathogens Escherichia coli O157:H7, Salmonella Typhimurium DT104, and Listeria monocytogenes Scott A in ground beef. Longissimus muscles from a DFD carcass (pH = 6.45) and normal carcass (N; pH = 5.64) were ground and samples obtained (100 and 0% DFD, respectively). Equal amounts of the 0 and 100% DFD ground samples were mixed to obtain 50% DFD samples. Inoculated 0, 50, and 100% DFD samples were packaged into oxygen-permeable overwrap and stored at 10 degrees C for E. coli O157:H7, Salmonella Typhimurium DT104, and L. monocytogenes Scott A or at 22 degrees C for E. coli O157:H7. Growth characteristics of E. coli O157:H7, Salmonella Typhimurium DT104, and L. monocytogenes Scott A did not differ (P > 0.05) between 0 and 100% DFD. Results indicated that the DFD beef used in this study was no more susceptible to growth of E. coli O157:H7, Salmonella Typhimurium, or L. monocytogenes Scott A than N beef.

Antibacterial activity in extracts of Camellia japonica L. petals and its application to a model food system

The potential presence of naturally occurring antimicrobials in petals of Camellia japonica L., a member of the tea family, was investigated against foodborne pathogens in microbiological media and food. Petals of the camellia flower (C. japonica L.) were extracted with methanol and fractionated into basic, acidic, and neutral fractions. The acidic fraction (equivalent to 1.0 g of raw sample per disk) produced an inhibitory zone of 14 to 19 mm (diameter) in a disk assay against the pathogens Salmonella Typhimurium DT104, Escherichia coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus on agar plates. Silica gel adsorption column chromatography, Sephadex LH-20 column chromatography, and preparative purification by high-pressure liquid chromatography were used to purify compounds in the fraction. The mass spectrum of the antibacterial compound isolated had a molecular ion (M+) of m/z 116 and showed good conformity with the spectrum of fumaric acid (HOOC-CH=CH-COOH). An aqueous extract from the petals of C. japonica L. had an inhibitory effect on growth of all pathogens at 37 degrees C in microbiological media by increasing the lag phase. None of the microorganisms was inhibited completely. Milk was used as a model food system. Aqueous extract at a concentration of 100 mg/ml was bacteriostatic against all the foodborne pathogens in the milk stored at 25 degrees C for up to 4 days.

Randomised controlled trial of ultrasonography in diagnosis of acute appendicitis, incorporating the Alvarado score

OBJECTIVES

To determine whether diagnosis by graded compression ultrasonography improves clinical outcomes for patients with suspected appendicitis.

DESIGN

A randomised controlled trial comparing clinical diagnosis (control) with a diagnostic protocol incorporating ultrasonography and the Alvarado score (intervention group).

SETTING

Single tertiary referral centre.

PARTICIPANTS

302 patients (age 5-82 years) referred to the surgical service with suspected appendicitis. 160 patients were randomised to the intervention group, of whom 129 underwent ultrasonography. Ultrasonography was omitted for patients with extreme Alvarado scores (1-3, 9, or 10) unless requested by the admitting surgical team.

MAIN OUTCOME MEASURES

Time to operation, duration of hospital stay, and adverse outcomes, including non-therapeutic operations and delayed treatment in association with perforation.

RESULTS

Sensitivity and specificity of ultrasonography were measured at 94. 7% and 88.9%, respectively. Patients in the intervention group who underwent therapeutic operation had a significantly shorter mean time to operation than patients in the control group (7.0 v 10.2 hours, P=0.016). There were no differences between groups in mean duration of hospital stay (53.4 v 54.5 hours, P=0.84), proportion of patients undergoing a non-therapeutic operation (9% v 11%, P=0.59) or delayed treatment in association with perforation (3% v 1%, P=0.45).

CONCLUSION

Graded compression ultrasonography is an accurate procedure that leads to the prompt diagnosis and early treatment of many cases of appendicitis, although it does not prevent adverse outcomes or reduce length of hospital stay.

Inguinoscrotal bruising: a sign of neonatal adrenal hemorrhage

A 5-day-old baby presented with right inguinoscrotal bruising. The underlying testis and cord were normal on examination. Intra-abdominal bleeding was suspected. Abdominal ultrasound showed right adrenal hemorrhage. This was managed nonoperatively and with supportive therapy; the inguinoscrotal bruising resolved spontaneously.

Microbiology of potatoes and potato products: a review

Many types of spoilage and pathogenic microorganisms exist on fresh, minimally processed, and fully processed potato products. Potatoes are processed into many products including frozen, dried, ready-to-eat, and minimally processed. The microbiological quality of finished potato products is influenced by the natural microflora, processing, handling, and human contact. The natural microflora of potatoes are influenced by soil and airborne inocula, agricultural practices, harvesting methods, and storage conditions. The microflora of processed products are influenced by all of the factors and conditions affecting the natural microflora as well as the processes applied to the product. Increased consumer demand for new and existing potato products highlights the importance of ensuring their microbiological safety. This review considers the sources of microorganisms, microflora, foodborne disease pathogens, and outbreaks associated with, and selected microbiological research involving, potatoes and potato products.

Activity of hydrolysed lactoferrin against foodborne pathogenic bacteria in growth media: the effect of EDTA

Lactoferrin was hydrolysed with pepsin and the antimicrobial activity of the resulting hydrolysate (HLF) was studied in 1% peptone, 0.05% yeast extract, 1% glucose (PYG) medium and tryptic soy broth (TSB). HLF was effective against Listeria monocytogenes, enterohaemorrhagic Escherichia coli and Salmonella enteritidis in PYG, however, the highest studied concentration (1.6 mg ml-1) did not inhibit growth of any of these organisms in TSB. The addition of EDTA enhanced the activity of HLF in TSB, indicating that the decreased activity of HLF may have been due, in part, to excess cations in the medium.

The experience of hope for survivors of acute myocardial infarction (AMI): a qualitative research study

This qualitative study was undertaken to explore the relevance and meaning of the experience of hope for survivors of acute myocardial infarction (AMI). Depth interviews were conducted with eight survivors (n = 8) of AMI at four weeks following discharge from hospital. Analysis of transcribed interviews revealed three distinct narrative themes. These were holding on to human connectedness, finding and harnessing the 'will' to live, and, having faith in the primacy of a higher power. Study findings are discussed in relation to the literature. Findings of the study assist in building knowledge and understanding of the complex phenomenon of hope. Implications for nursing practice and research are drawn from study findings.

Graded compression ultrasonography in the assessment of the "tough decision" acute abdomen in childhood

The diagnosis of acute appendicitis in childhood is frequently difficult. In some situations the need to operate is clear, but in others the decisions may be much "tougher" because the clinical findings are equivocal. This is a retrospective study of a consecutive series of 253 children presenting with "acute abdominal pain? appendicitis" who had graded compression ultrasonography (GCUS) because the clinical scenario did not warrant immediate laparotomy. This represents 30% of all cases seen in the study period. The aim of the study was to examine the role of GCUS and a clinical scoring system (the Alvarado score) in patients in whom the diagnosis is uncertain.

The experiences of female spouses of survivors of acute myocardial infarction: a pilot study of Lebanese-born women in south-western Sydney, Australia

Lebanese migrants form a significant proportion of the population in southwestern Sydney (SWS), and in New South Wales, Australia. This pilot study was undertaken in south-western Sydney, a rapidly expanding and socioeconomically disadvantaged region, to explore the experiences of English speaking women of Lebanese origin whose spouses had recently experienced an acute myocardial infarction (AMI). Semi-structured interviews were conducted with seven Lebanese-born women at 2- and 4-week intervals, following the discharge of their husbands from hospital. Qualitative analysis of narrative text revealed four distinct themes. These were: struggle to resolve distress; intensive monitoring of the AMI survivor; searching for avenues of support; and reflecting on the future. Study findings are discussed in relation to the literature. Implications for nursing practice and research are drawn from study findings.

Effect of oscillatory high hydrostatic pressure treatments on Byssochlamys nivea ascospores suspended in fruit juice concentrates

The effect of continuous (689 MPa with holding times of 5, 15 or 25 min) and oscillatory (one, three or five cycles at 689 MPa with holding times of 1 s) high hydrostatic pressure treatments on the viability of Byssochlamys nivea ascospores suspended in apple and cranberry juice concentrates adjusted by dilution to water activities (aw) of 0.98 and 0.94 was evaluated at 21 and 60 degrees C. Inactivation of the initial spore inocula was achieved after three or five cycles of oscillatory pressurization at 60 degrees C when the aw was 0.98 in both fruit juices. With aw 0.94, the initial inocula were reduced by less than 1 log-cycle after five pressure cycles. Inactivation was not observed within 25 min with continuous pressurization at 60 degrees C. In treatments at 21 degrees C, no effect on spore viability was observed with continuous or oscillatory treatments.

High hydrostatic pressure come-up time and yeast viability

The effects of the come-up time at selected pressures (50 to 689 MPa) on Saccharomyces cerevisiae and Zygosaccharomyces bailii viability were evaluated at 21 degrees C. For Z. bailii the effects of the water activity (a(w)) of the suspension media and the stage of the growth cycle were also investigated. Pressure come-up times exerted an important effect on the yeast survival fraction, decreasing counts as pressure increased. An increased sensitivity to pressure treatments was observed with yeast cells from the exponential growth phase. Lethality increased as a(w) of the suspension media increased. For an a(w) of 0.98 and cells from the stationary growth phase, pressure treatments at less than 200 MPa had no effect on Z. bailii viability; however, no survivors (< 10 CFU/ml) were observed in treatments applied only for the time needed to reach pressures greater than 517 MPa. Yeast survivor curves showed an excellent fit (r > 0.996) when described by a phenomenological model based on the Fermi equation, S(P) = 1/¿1 + exp[(P - Pc)/k]¿, where S(P) is the survival fraction, P is the pressure, Pc is a critical pressure corresponding to 50% survival, and k is a constant representing the steepness of the curve.

Evaluation of Four Pea ( Pisum sativum ) Cultivars in PE-2 Medium for the MPN Enumeration of Anaerobic Spore-Forming Organisms

Untreated 'Alaska' seed peas have traditionally been used to prepare PE-2 medium, a medium used to recover anaerobic bacteria. Three cultivars of seed peas, 'Columbian', 'Yellow', and 'Scotch' were compared to the cultivar 'Alaska' peas in PE-2 for recovery of Clostridium butyricum ATCC 860, Clostridium sporogenes ATCC 7955/NCA 3679, and Thermoanerobacterium thermosaccharolyticum ATCC 25773 determined by using the most probable number (MPN) technique. Organisms were grown in cooked meat medium (CMM) and enumerated by the three-tube MPN method in PE-2 media incubated at 37°C for 48 h. Recovery of C. butyricum and T. thermosaccharolyticum grown in homogenates of commercial cream-style corn and vegetable beef soup were also evaluated. Similar recovery of organisms from stock cultures or from foodstuffs were observed in PE-2 prepared with three of the pea cultivars ('Alaska', 'Columbian', and 'Yellow'). While the 'Scotch' cultivar PE-2 medium yielded recoveries comparable to PE-2 prepared with the other pea cultivars, turbid tubes were occasionally observed from which viable microorganisms could not be recovered. This cultivar is therefore not recommended due to the probability of yielding false positives in the MPN technique.

Thromboembolic risks of left atrial thrombus detected by transesophageal echocardiogram

Patients with left atrial thrombus are considered at high risk for thromboembolic events. The actual prognosis of these patients and the features most predictive of future events are unclear. We performed transesophageal echocardiograms in 2,894 patients over a 6 1/2-year period; 94 (age 69 +/- 11 years, 59 men, 83 in atrial fibrillation) were found to have left atrial thrombus. The thrombi were considered mobile in 45 patients and 33 patients had thrombus with a maximum dimension > or = 1.5 cm. Seven of the 94 patients with prosthetic valves were excluded from follow-up analysis. Over a follow-up period of 25.3 +/- 19.2 months, 17 patients had suffered a stroke or embolic event (event rate 10.4% per year) and 27 had died (mortality 15.8% per year). Cox proportional hazard regression analysis identified a maximum thrombus dimension > or = 1.5 cm (RR 19, p = 0.002), history of thromboembolism (RR 4.2, p = 0.038), and mobile thrombus (RR 5.3, p = 0.02) as predictors of subsequent thromboembolism. Moderate or severe left ventricular dysfunction was the only significant predictor of death (RR 2.9, p = 0.04). Gender, age, warfarin therapy at follow-up, atrial fibrillation, location (cavity vs appendage) of thrombus, and spontaneous echocardiographic contrast were not significant. Aggressive antithrombotic therapy may be indicated in these high-risk patients.

Isolation and identification of antimicrobial furocoumarins from parsley

Photoactive furocoumarins extracted from four varieties of fresh and freeze-dried parsley leaves inhibited a DNA repair-deficient Escherichia coli in a photobiological assay. Using media-modified assays, the human pathogens E. coli O157:H7 and Listeria monocytogenes, the spoilage microorganism Erwinia carotovora, and Listeria innocua were also inhibited. Pseudomonas fragi was not inhibited. Minimum concentrations of Forest Green parsley powder in agar which showed inhibition ranged from 0.12% to 8.0% depending on the microorganism. Ultraviolet light (UV) at 365 nm for 60 min used to photoactivate the furocoumarins in the bioassay had little effect on L. monocytogenes and L. innocua. A slight UV inhibitory effect was detected with E. carotovora. Furocoumarins, psoralen, 8-methoxypsoralen (8-MOP), 5-methoxypsoralen (5-MOP), oxypeucedanin and isopimpinellin were identified using gas chromatography-mass spectrometry. Psoralen, 8-MOP, and 5-MOP were quantified. A difference in relative furocoumarin concentration (weight of furocoumarin per weight of dry parsley leaves) for all varieties of parsley was revealed. The concentration of 5-MOP was significantly greater than 8-MOP (P < 0.05), but not significantly greater than psoralen. Psoralen and 8-MOP were not significantly different in concentration.

How to avoid complications during percutaneous endoscopic gastrostomy

Percutaneous endoscopic gastrostomy (PEG) has advantages over open gastrostomy, and is an accepted technique for children. However, a number of technical problems may be encountered during insertion. This report identifies those problems and proposes precautions that can be taken to reduce their likelihood. Recognized major complications include esophageal injury, colonic perforation, wound infection, gastric erosion by the gastrostomy tube, and later symptomatic gastroesophageal reflux requiring correction by fundoplication.

Technique and complications of percutaneous endoscopic gastrostomy in children

Percutaneous endoscopic gastrostomy (PEG) is now a well-established technique in children. In this study of 63 children (mean age 7.8 years, youngest 2.4 months), technical problems associated with insertion of the gastrostomy tube, and complications related to the procedure, were analysed. Complications included wound infection, oesophageal injury (probably sustained during extraction of the guide wire) and symptomatic gastro-oesophageal reflux (GOR) occurring after PEG insertion. Many of these complications can be avoided or reduced in likelihood by refinements to the technique of insertion.