Evaluation of a Chemiluminescence Method for Measuring Alkaline Phosphatase Activity in WholeMilk of Multiple Species and Bovine Dairy Drinks: Interlaboratory Study

Alkaline phosphatase (ALP) is a ubiquitous enzyme in milk with timetemperature destruction similar to that of certain pathogens destroyed in pasteurization. Measurement of ALP to indicate proper pasteurization is a common practice. Recently the public health level for ALP was decreased to 350 mU/L, a level below the sensitivity of older colorimetric ALP methods. This study was conducted within the structure of the International Dairy Federation and the International Organization for Standardization to evaluate the reproducibility of the chemiluminescence method (Charm PasLite) for ALP at 50, 100, 350, and 500 mU/L in whole milk of multiple species to meet new regulations in the United States and proposed regulations in the European Union (EU). Fifteen laboratories from 8 countries evaluated bovine, goat, sheep, and buffalo milk, bovine skim milk, 20% fat cream, and 2% fat chocolate milk. At ALP levels of 350 and 500 mU/L, the average relative standard deviation for repeatability (RSDr) was 7.5%, and the average relative standard deviation of reproducibility was (RSDR) 15%. For ALP at 100 and 50 mU/L, the average RSDr values were 10.5 and 12.6%, respectively, and the average RSDR values were 18 and 25%, respectively. The limit of detection was 20 mU/L. Results are comparable to those obtained with other enzymatic photo-activated system methods such as the fluorometric method. Results indicate that the method is suitable for measuring ALP in the milk of multiple species and in dairy drinks at U.S. and proposed EU levels.

Measurement of the [Formula: see text] production cross-section using [Formula: see text] events with [Formula: see text]-tagged jets in [Formula: see text] collisions at [Formula: see text] and 8 TeV with the ATLAS detector

The inclusive top quark pair ([Formula: see text]) production cross-section [Formula: see text] has been measured in proton-proton collisions at [Formula: see text] and [Formula: see text] with the ATLAS experiment at the LHC, using [Formula: see text] events with an opposite-charge [Formula: see text] pair in the final state. The measurement was performed with the 2011 7 TeV dataset corresponding to an integrated luminosity of 4.6 [Formula: see text] and the 2012 8 TeV dataset of 20.3 [Formula: see text]. The numbers of events with exactly one and exactly two [Formula: see text]-tagged jets were counted and used to simultaneously determine [Formula: see text] and the efficiency to reconstruct and [Formula: see text]-tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section was measured to be: [Formula: see text]where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, knowledge of the integrated luminosity and of the LHC beam energy. The results are consistent with recent theoretical QCD calculations at next-to-next-to-leading order. Fiducial measurements corresponding to the experimental acceptance of the leptons are also reported, together with the ratio of cross-sections measured at the two centre-of-mass energies. The inclusive cross-section results were used to determine the top quark pole mass via the dependence of the theoretically predicted cross-section on [Formula: see text] giving a result of [Formula: see text][Formula: see text] GeV. By looking for an excess of [Formula: see text] production with respect to the QCD prediction, the results were also used to place limits on the pair-production of supersymmetric top squarks [Formula: see text] with masses close to the top quark mass, decaying via [Formula: see text] to predominantly right-handed top quarks and a light neutralino [Formula: see text], the lightest supersymmetric particle. Top squarks with masses between the top quark mass and 177 GeV are excluded at the 95 % confidence level.

Measurement of the [Formula: see text] production cross-section using [Formula: see text] events with [Formula: see text]-tagged jets in [Formula: see text] collisions at [Formula: see text] and 8 TeV with the ATLAS detector

The inclusive top quark pair ([Formula: see text]) production cross-section [Formula: see text] has been measured in proton-proton collisions at [Formula: see text] and [Formula: see text] with the ATLAS experiment at the LHC, using [Formula: see text] events with an opposite-charge [Formula: see text] pair in the final state. The measurement was performed with the 2011 7 TeV dataset corresponding to an integrated luminosity of 4.6 [Formula: see text] and the 2012 8 TeV dataset of 20.3 [Formula: see text]. The numbers of events with exactly one and exactly two [Formula: see text]-tagged jets were counted and used to simultaneously determine [Formula: see text] and the efficiency to reconstruct and [Formula: see text]-tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section was measured to be: [Formula: see text]where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, knowledge of the integrated luminosity and of the LHC beam energy. The results are consistent with recent theoretical QCD calculations at next-to-next-to-leading order. Fiducial measurements corresponding to the experimental acceptance of the leptons are also reported, together with the ratio of cross-sections measured at the two centre-of-mass energies. The inclusive cross-section results were used to determine the top quark pole mass via the dependence of the theoretically predicted cross-section on [Formula: see text] giving a result of [Formula: see text][Formula: see text] GeV. By looking for an excess of [Formula: see text] production with respect to the QCD prediction, the results were also used to place limits on the pair-production of supersymmetric top squarks [Formula: see text] with masses close to the top quark mass, decaying via [Formula: see text] to predominantly right-handed top quarks and a light neutralino [Formula: see text], the lightest supersymmetric particle. Top squarks with masses between the top quark mass and 177 GeV are excluded at the 95 % confidence level.

Internally-developed electronic reporting system for medication errors

To date, no work has been published regarding internal electronic patient safety reporting systems in the Irish hospital setting and limited international data is available regarding the impact of such programmes. In this report we describe the successful design and implementation of an online medication error reporting system in a 1017-bed Irish teaching hospital. In-house development has resulted in a system tailored to the needs of the hospital, with the flexibility to adapt to the future demands of the medication safety programme. Its introduction has led to a positive impact on reporting rates and on data management and has facilitated the development of safety initiatives.

Comparative growth of Bacteroides species in various anaerobic culture media

The growth of five species of Bacteroides in four anaerobic culture media was continuously monitored turbidimetrically. Interspecies differences were observed in the growth of Bacteroides spp. in the various media, but growth in Brain Heart Infusion broth supplemented with yeast extract, haemin and menadione, was consistently better than in Wilkins-Chalgren, Thioglycollate or Schaedler broths. Microscopy of cultures grown overnight in Brain Heart Infusion broth showed that the bacteria exhibited normal morphology but most species grown in the other media displayed filamentation or chain formation. Four of the five species grown in Schaedler broth also exhibited spheroplast formation. This morphological change occurred in the stationary phase of growth, was reduced by inclusion of NaCl in the medium and was abolished in Schaedler broth prepared at double the recommended strength.

A micro-chamber for continuous microscopic monitoring of anaerobic bacteria

A recently developed apparatus is described that allows continuous microscopic monitoring of bacteria grown in anaerobic conditions. Four species of Bacteroides were tested using this equipment and normal and reproducible growth rates were obtained in all cases.

Continuous opacity monitoring of the growth of bacteria under strict anaerobic conditions

A newly designed instrument is described which generates continuous records of the opacities of six bacterial cultures growing under strict anaerobic conditions. Additions (for example, of antibacterial agents) or withdrawal of culture (for example, for viable counting) can be made at any time without breach of anaerobiosis. Use of the instrument is illustrated by growth curves obtained from small inocula of two strict anaerobes, Bacteroides asaccharolyticus and Peptostreptococcus anaerobius and by the effects on the growth curve of Bacteroides fragilis of adding various concentrations of metronidazole at different times.

Therapeutic significance of nocardicin A stimulation of phagocyte function in experimental Pseudomonas aeruginosa infection

Nocardicin A, a monocyclic beta-lactam antibiotic with modest anti-pseudomonal activity in vitro, controlled an otherwise fatal Pseudomonas infection in mice when given in doses which produced blood levels well below the minimum bactericidal concentration. In even smaller doses, it converted the partial protection afforded by modest doses of carbenicillin into full protection. Human polymorphonuclear leucocytes exposed to low concentrations of the drug in vitro and peritoneal macrophages recovered from mice treated with nocardicin A exhibited an unusually specific form of enhanced activity. Chemotaxis and phagocytosis were not affected, but intracellular killing of Ps. aeruginosa was significantly increased. This was shown to be due to an effect on the phagocyte and not to facilitated killing of organisms damaged by extracellular exposure to the antibiotic. It is argued that the effect on phagocyte function is sufficient to contribute materially to the therapeutic effect of nocardicin A.

Semiautomated determination of minimum bactericidal concentrations of antibiotics

Using a newly devised 50-channel photometer which records the opacity of growing bacterial cultures, it was shown that the time taken by cultures diluted 1/1000 in fresh broth to reach 50% of the opacity of a fully grown culture was inversely related to the concentration of organisms in the original culture. This relation was used to determine the numbers of survivors after exposure to benzylpenicillin and gentamicin alone and in combination. The procedure is commended as a labour-saving and potentially rapid method of obtaining comprehensive information on the bactericidal action and interaction of antibiotics.

In-vitro activity of the novel oxa-beta-lactam antibiotic moxalactam (LY 127935) against dense populations of selected Gram-negative bacilli

The activity of moxalactam, a new beta-lactam antibiotic with a novel molecular structure, was examined against dense populations of a variety of Gram-negative bacilli. The lytic activity of moxalactam against ampicillin-sensitive strains was similar to ampicillin, but the activity was maintained against ampicillin-resistant strains, including Pseudomonas aeruginosa, irrespective of whether the ampicillin resistance was 'intrinsic' (non-enzymic) or due to beta-lactamase. Of the 18 strains tested only one, a Hafnia sp., failed to respond to moxalactam.

Factors affecting antibiotic concentrations in bladder urine

High, but transient, antibiotic levels are achieved in bladder urine if a rapidly excreted agent is given to a patient with frequency of micturition and a normal residual bladder volume. Lower, but more prolonged levels are achieved if the drug is slowly excreted, if micturition is infrequent, or if the residual volume is increased. The magnitude of these effects has been calculated mathematically for various combinations of circumstances. Such considerations have implications for treatment, particularly with drugs, such as the beta-lactam group, that are rapidly excreted into urine.

A microcomputer-based research system for the optical analysis of agar-cultured micro-organism colonies

A system which has been developed for the automatic of agar-cultured microorganism colonies is described. A camera of the line-scanning type is used to scan the plates and details of the hardware and software development are explained. Flow diagrams are included which illustrate the operation of the system, but, as yet, no results are available. The prototype machine is undergoing evaluation testing.

Comparative in vitro activities of cefotaxime and ceftizoxime (FK749): new cephalosporins with exceptional potency

Cefotaxime and its desacetoxymethyl derivative, ceftizoxime (previously known as FK749), are both extremely active against a wide spectrum of bacteria. In the present comparative study, the activity of ceftizoxime exceeded that of cefotaxime by a factor of four or more for strains of Klebsiella, Enterobacter, Providencia, Serratia, and Bacteroides; the only species for which the activity of cefotaxime exceeded that of ceftizoxime by a factor of four was Vibrio cholerae. Against other species, the activity of the two drugs was roughly comparable. Both showed outstanding activity against Haemophilus influenzae and Neisseria gonorrhoeae. Comparative turbidimetric and morphological studies revealed that ceftizoxime was able to induce spheroplast formation and rapid lysis in Escherichia coli strains at lower concentrations than cefotaxime. This difference was not found, however, when E. coli strains resistant to ampicillin by an intrinsic (nonenzymic) mechanism were tested.

Response of Escherichia coli to Beta-lactam antibiotics: effect of the concomitant presence of staphylococci exhibiting inducible Beta-lactamase activity

The response to Beta-lactam antibiotics of mixed cultures of Escherichia coli and Staphylococcus epidermidis was studied in static culture and in an in vitro model which simulates the dynamic conditions in which bacteria are exposed to antibiotics in the treatment of urinary infection. In static cultures, the concomitant presence of staphylococci exhibiting inducible Beta-lactamase activity substantially reduced the efficacy of benzylpenicillin and ampicillin (but not cefuroxime) against E. coli. In the conditions of the bladder model some interference with the activity of Beta-lactam antibiotics by Beta-lactamase producing staphylococci was also demonstrated. Nevertheless, relatively modest doses of ampicillin were still able to suppress growth of susceptible E. coli for periods exceeding the normal interdose interval, even in the presence of enzyme-producing staphylococci.

Increasing importance of plasmid-mediated trimethoprim resistance in enterobacteria: two six-month clinical surveys

All clinical isolates of enterobacteria received at the laboratory were monitored for trimethoprim resistance over six months in 1978. The survey was repeated in 1979 and the incidence of trimethoprim resistance showed a slight decrease, but the proportion of resistant strains owing their trimethoprim resistance to transferable R plasmids had almost trebled. There was also a large increase in the proportion of resistant strains exhibiting high-level non-transferable trimethoprim resistance. These findings suggest transposition of genes conferring trimethoprim resistance from plasmids to the bacterial chromosome.

Uropathogenic properties of Escherichia coli in recurrent urinary-tract infection

Properties of Escherichia coli considered to be important in the pathogenesis of urinary-tract infection were investigated. The following properties were more common in E. coli strains isolated from urinary infections than in periurethral strains from healthy individuals: (i) O serogroups 2, 4, 6, 8, 18ab and 75; (ii) high K-antigen titre; (iii) production of haemolysin; (iv) production of fimbriae; (v) fermentation of salicin. The correlation between isolation of a strain from the urinary tract and possession of any single property was not strong; however, strains rich in a combination of these pathogenic properties were rarely isolated from the periurethral area of healthy subjects but were common in urinary infections. Nevertheless, a significant proportion of urinary strains had few pathogenic properties. Strains rich in pathogenic properties were more commonly isolated from upper urinary-tract infections than from lower-tract infections; this indicates that the properties of the invading organism may influence the localisation of infection.

Resistance to antimicrobial agents of Vibrio cholerae E1 Tor strains isolated during the fourth cholera epidemic in the United Republic of Tanzania

Isolates of Vibrio cholerae obtained immediately after the outbreak of the fourth recorded epidemic of cholera in the United Republic of Tanzania were sensitive to tetracycline, but after five months of its extensive therapeutic and prophylactic use, 76% of the isolates were observed to be resistant to this and other antimicrobial agents. The appearance of resistance was found to be due to the rapid spread of antibiotic resistance plasmids belonging to the C incompatibility complex. Although most plasmid incompatibility groups have been shown to be unstable in V. cholerae, the strains found in the present epidemic seem to carry a plasmid belonging to one of the few relatively stable groups. These findings emphasize the importance of monitoring any emergence of bacterial resistance that may occur when mass prophylaxis programmes are in operation and also the importance of determining the genetic basis of the resistance mechanism.

An in vitro model for assessing optimum antibiotic dosage in urinary tract infection

Experimental and clinical data from which dosage regimens can be rationally deduced are generally lacking. As an approach to this problem, an in vitro model of the urinary bladder has been constructed in which the conditions of exposure of bacteria to antibacterial drugs which exist in the treatment of cystitis are simulated. Results obtained so far correlate well with such clinical information as we possess and have helped to define more accurately the conditions which govern successful therapy of urinary infection. The most recent data suggest that much lower doses of some beta-lactam antibiotics than have been contemplated hitherto may be effective in the treatment of uncomplicated cystitis.

Thiamphenicol and chloramphenicol: an in vitro comparison with particular reference to bactericidal activity

Chloramphenicol is bacteristatic for most species but bactericidal for Haemophilus influenzae and Neisseria meningitidis. Despite its generally lower activity, thiamphenicol exhibited equal or greater activity against these two species than did chloramphenicol. It is suggested that a particular place might be defined for thiamphenicol in the treatment of infection due to these two organisms.

Emergence of trimethoprim-resistant enterobacteria in patients receiving long-term co-trimoxazole for the control of intractable urinary-tract infection

In patients with previously intractable urinary-tract infection treated with low-dose co-trimoxazole for 6--58 (mean 32.7) months, the percentage of infected urines fell from 41.4 before treatment to 6.3 during treatment. Only 6 episodes of infection were due to trimethoprim-resistant bacteria. Results in a small group of patients in whom treatment was continued with trimethoprim alone were similar. Under the conditions of this study, long-term control of urinary-tract infection was not materially compromised by breakthrough infections due to trimethoprim-resistant organisms.

An in vitro evaluation of clavulanic acid, a potent, broad-spectrum beta-lactamase inhibitor

The in vitro efficacy of clavulanic acid, a new broad-spectrum inhibitor of enterobacterial beta-lactamases, was investigated. In conventional agar dilution tests, the presence of a sub-inhibitory level of clavulanic acid (8 microgram/ml) lowered the minimum inhibitory concentration of ampicillin for many resistant enterobacteria to therapeutically achievable levels. When tested against dense populations of Escherichia coli and klebsiella strains in a static turbidimetric system and in an in vitro model of the treatment of bacterial cystitis, clavulanic acid plus ampicillin suppressed bacterial growth for periods far exceeding the normal interdose interval at concentrations at which neither agent alone was effective. In addition to its activity as a beta-lactamase inhibitor, clavulanic acid may interact with other beta-lactam antibiotics in a second, distinct way. Because of this synergic interactions may occur with non-beta-lactamase producing organisms, and the overall synergic effect obtained with beta-lactamase producers may be compounded of two separate elements.

In vitro model simulating the form of exposure of bacteria to antimicrobial drugs encountered in infection

A new model, which is designed to investigate the in vitro activity of antibiotics as a function of different concentration-time curves, is described. The antibiotic is allowed to diffuse through a membrane into a bacterial culture until a peak level is reached; the antibiotic is then removed by flow-assisted back diffusion. With this arrangement it is possible to expose bacteria to a changing concentration of drug while maintaining a constant volume of bacterial culture. Preliminary studies were carried out to investigate the response of a strain of Escherichia coli to gentamicin. The results indicate that bacteria surviving exposure to concentrations of gentamicin similar to those obtained during therapy may exhibit an increase in resistance to the antibiotic.

The response of Staphylococcus aureus to benzylpenicillin

The response to benzylpenicillin of 2 strains of Staphylococcus aureus was investigated in vitro using 3 techniques in parallel: continuous turbidimetric monitoring, continuous microscopic monitoring, and thin-section electron microscopy. Cultures of staphylococci were exposed to several concentrations of penicillin for various intervals of time before terminating the antibiotic activity with penicillinase. Bacterial lysis by penicillin was concentration-dependent and showed an optimal dosage effect which was very marked for one of the strains. The growth and division of cells continued for up to 1 h in the presence of penicillin. A variety of morphological responses was observed at each penicillin concentration. These changes ranged from complete bacterial lysis to apparently normal cells, and included several different types of aberrant morphological forms. On addition of penicillinase to cultures exposed to penicillin, there was a time interval before survivors began to divide. This period was increased by raising the concentration of penicillin or by increasing the period of exposure to penicillin. Bacteria resuming growth after surviving penicillin action exhibited markedly aberrant septation. Most of the survivors were found to originate from clumps of cocci rather than from individual cells or small groups.

Factors governing the emergence of resistance to nalidixic acid in treatment of urinary tract infection

Cultures of Escherichia coli were exposed to nalidixic acid in an in vitro model in which the conditions of drug-organism interaction resembled those of bacterial cystitis treatment. Results obtained in this way suggested that emergence of bacterial resistance should not be a major problem in treatment of uncomplicated urinary infection; such cases might indeed respond to a less intensive course of treatment than is usual. More prolonged, high-dosage therapy with nalidixic acid may be required for patients with more complicated infections if the risk of failure from the emergence of bacterial resistance is to be minimized.

Is your dosage really necessary? Antibiotic dosage in urinary infection

Dense cultures of bacteria were exposed to changing concentrations of beta-lactam antibiotics in an in-vitro model of the urinary bladder. The results suggest that uncomplicated urinary infection may respond to lower doses than are usually given without compromising the success of subsequent treatment in those cases in which such minimal treatment fails.

The activity of polymyxins against Escherichia coli in an in-vitro model of the urinary bladder

The activities against a strain of Escherichia coli of polymyxin B, colistin (polymyxin E) and their sulphomethyl derivatives sulphomyxin and colistin sulphomethate have been examined in an in-vitro model of the urinary bladder under conditions similar to those that may operate in the therapeutic situation. In the dynamic conditions of the model, polymyxins exhibited a reduced activity against E. coli in comparison with activity against exponentially growing cultures in a static system. Nevertheless, long-term suppression of bacterial growth was achieved with levels of polymyxin B and colistin that can be attained during therapy, whereas sulphomethylpolymyxins had little effect on bacterial growth even on prolonged exposure.

R plasmids from Asian strains of Vibrio cholerae

Five R plasmids transferred from Asian strains of Vibrio cholerae all proved to be members of compatibility group C. A non-self-transmissible plasmid, stable in V. cholerae, was mobilized for transfer to Escherichia coli K-12 and found to be unstably inherited in that host. Plasmids of group C and P transferred to a wild V. cholerae strain were stably inherited.

The in vitro activity of ceftezol (demethylcefazolin) against dense populations of Escherichia coli

The activity of ceftezol was examined by continuous turbidimetric monitoring of dense populations of Escherichia coli exposed to the drug. Although ceftezol was found to be very active against strains of E. coli, its activity was consistently less than that of the closely related antibiotics, cefazolin. This difference was also found when strains of E. coli were examined in a dynamic system which simulates some of the conditions in which bacteria and drug interact in the treatment of bacterial cystitis. Evidence is presented that the difference in activity between the two cephalosporins resides in a differential ability to induce certain morphological changes in E. coli and in a differential rate of destruction by escherichial beta-lactamases.