Effect ofBacteroides fragilis grown in the presence of clindamycin,metronidazole and fusidic acid on opsonization and killing ofEscherichia coli

Bactericidal action of human polymorphonuclear leucocytes on Escherichia coli in the presence of Bacteroides fragilis grown in subinhibitory concentrations of clindamycin, metronidazole and fusidic acid was studied.Bacteroides fragilis grown in the absence of drugs significantly inhibited the killing of Escherichia coli.Bacteroides fragilis grown in the presence of the drugs had a reduced inhibitory effect on the killing of Escherichia coli but this reduction was only significant for Bacteroides fragilis grown in 1/2 MIC of clindamycin. The phagocytosis of Bacteroides fragilis grown with and without clindamycin, as measured by killing, was the same. Complement consumption of Bacteroides fragilis grown with and without clindamycin did not differ. Clindamycin-treated Bacteroides fragilis fixed C3 to a significantly lower degree than did untreated bacteria. The chemiluminescence of Escherichia coli opsonized with serum preincubated with clindamycin-treated Bacteroides fragilis was significantly higher than with serum preincubated with untreated bacteria. These results suggested that in killing experiments of mixed Escherichia coli and Bacteroides fragilis,the mechanism underlying the reduced inhibitory capacity of clindamycin-exposed Bacteroides fragilis is related to greater availability of C3 in serum for opsonization of Escherichia coli.     

Predictive value of surveillance cultures for systemic infection due toCandida species

Weekly fungal surveillance cultures (1,542 cultures) of urine (475), stool (520) and oropharyngeal (547) specimens from 111 patients on the bone marrow transplant and hematologic malignancy services were analyzed. Forty-three percent of the patients were colonized by Candida albicans and 10.8 % by Candida tropicalis. There were 22 proven systemic fungal infections, ten due to Candida albicans,eight to Candida tropicalis,one each to Candida pseudotropicalis and Torulopsis glabrata,and two to Aspergillus species. Positive surveillance cultures for Candida tropicalis were highly predictive of systemic infection. The finding of two or more positive cultures yielded high positive predictive values (100%) as a function of body site. Positive surveillance cultures for Candida albicans were not predictive of disease but negative cultures for Candida albicans and Candida tropicalis had a high negative predictive value (95–99 %). Surveillance culture data for specific Candida species may aid in diagnostic and therapeutic decision making.     

Analysis of dimycocerosates of glycosylphenolphthiocerols in the identification of some clinically significant mycobacteria

Extracts of representative mycobacteria were examined by thin-layer chromatography for glycosylphenolphthiocerol dimycocerosates. The glycolipid typical of Mycobacterium bovis was also found in Mycobacterium africanum and Mycobacterium microti,but it was absent in Mycobacterium bovis AN 5.Mycobacterium gastri strains contained a glycolipid which was chromatographically similar to that in Mycobacterium kansasii.Representatives of Mycobacterium marinum produced a distinct glycolipid type, and one strain had major amounts of a more polar variant. The sugar moieties of purified lipids, including that from Mycobacterium leprae,were identified by thin-layer chromatography of methyl glycosides in acid methanolysates.     

Comparative in vitro activity of the new oral cephalosporin BMY-28100

Using a broth microdilution method, the in vitro activity of BMY-28100 against 365 clinical strains of commonly isolated bacteria was determined. BMY-28100 showed good activity against streptococci, methicillin-susceptible staphylococci,Salmonella spp.,Shigella spp., and beta-lactamase producing Branhamella catorrhalis and Haemophilus influenzae.Against susceptible strains of these organisms, BMY-28100 showed activity comparable to that of penicillin G, ampicillin, co-trimoxazole, erythromycin, cefaclor, doxycycline and amoxicillin/potassium clavulanate. BMY-28100 had moderate activity against Arizona hinshawii and poor activity against Campylobacter jejuni and Yersinia enterocolitica.     

Clostridium difficile-Associated diarrhoea in uremic patients

An outbreak of 94 episodes of Clostridium difficile-associated diarrhoea in 62 patients in a nephrology ward over a two-year period was investigated. Quantitative stool cultures were performed on ten uremic patients not on antibiotics and without diarrhoea and on ten healthy controls. All diarrhoeal episodes were associated with Clostridium difficile,and no other bacterial pathogens were isolated. Thirty-two relapses occurred in 16 patients, fourteen of the relapses without preceding antibiotic exposure.Clostridium difficile could not be isolated from the environment of the patients. Uremic patients, who had a significantly increased number of Clostridium spp. in their stools, are predisposed to Clostridium difficile infections.     

Comparative in vitro activity of LY146032 (Daptomycin) against gram-positive cocci

The in vitro activity of LY146032 was compared with those of seven other antimicrobial agents against gram-positive cocci. MICs of LY146032 were lowest for Streptococcus pneumoniae and methicillin-susceptible Staphylococcus epidermidis (0.25 mg/l).For methicillin-resistant Staphylococcus epidermidis and Staphylococcus aureus the MICs were 1 mg/l, for Enterococcus faecalis 2 mg/l and for Enterococcus faecium 4 mg/l. The activity of LY146032 was in general higher than that of vancomycin. Time-kill studies showed LY146032 had higher bactericidal activity than vancomycin against a methicillin-resistant Staphylococcus aureus strain, and bactericidal activity against Enterococcus faecalis and Enterococcus faecium.     

The Impact of PACS on Radiologists’ Work Practice

This paper identifies and analyzes how the implementation and use of picture archiving and communication system impacts radiologists’ work practice. The study is longitudinal from 1999 to 2005 and have a qualitative perspective were data were collected by structured interviews in a total of 46. The interviews were transcribed, analyzed, and coded using grounded theory as an organizing principle. In radiologists’ work practice, three main categories were defined: professional role, diagnostic practice, and technology in use. The changing trends within the professional role indicated that radiologists moved from a more individual professional expertise to become more of an actor in a network. The diagnostic practice changed, as reading x-ray films was seen as an art form in 1999, requiring years of training. Once everyone could view digital images, including 3-dimensional technology, it was easier for other clinicians to see and interpret the images and the skills become accessible to everyone. The change in technology in use as a result of the shift to digital images led to an increased specialization of the radiologist.     

Effect of RO 23-6240 on sensitive and resistant intracellular mycobacteria

The activity of Ro 23-6240 and rifampicin against intracellular Mycobacterium fortuitum and Mycobacterium chelonei was assessed in vitro over a 48-hour period. Both agents, at an extracellular concentration of 2.0 mg/l (Ro 23-6240) and 1.0 mg/l (rifampicin), produced a significant intracellular killing of the sensitive Mycobacterium fortuitum at both 20 and 48 hours. However, neither agent was effective against the resistant Mycobacterium chelonei.It was concluded that Ro 23-6240 has a direct antimicrobial effect against sensitive intracellular mycobacteria.     

Incidence and virulence ofAeromonas species in feces of children with diarrhea

Aeromonas spp. occurring in feces of children with diarrhea were studied. Forty-eight strains were isolated from 2,025 specimens during a one year period. Only 11 of 44 strains tested yielded virulence factors (cytotoxin, hemolysin and hemagglutinin). Six strains were identified as Aeromonas sobria and five as Aeromonas hydrophila.The other strains isolated were identified as Aeromonas caviae.The biochemical characteristics associated with virulence factors were a positive Voges-Proskauer reaction, production of gas from glucose, fermentation of mannose, and absence of -lactosidase. Beta-D-glucosidase and esculin hydrolysis were the main characteristics used to differentiate Aeromonas sobria from the other two species. The incidence of Aeromonas spp. with virulence factors in feces of children with diarrhea would seem to vary widely from one area to another.     

Functional analysis of the ABF1-binding sites within the Ya regions of the MATa and HMRa loci of Saccharomyces cerevisiae

Cell type in the yeast Saccharomyces cerevisiae is determined by information present at the MAT locus. Cells can switch mating types when cell-type information located at a silent locus, HML or HMR, is transposed to the MAT locus. The HML and HMR loci are kept silent through the action of a number of proteins, one of which is the DNA-binding protein, ABF1. We have identified a binding site for ABF1 within the Ya region of MAT a and HMR a. In order to examine the function of this ABF1-binding site, we have constructed strains that lack the site in the MAT a or HMR a loci. Consistent with the idea that ABF1 plays a redundant role in silencing, it was found that a triple deletion of the ABF1-binding sites at HMRE, Ya and I did not permit the expresion of HMR a. We have also shown that chromosomal deletion of the binding site at MATY a had no effect on the level of cutting by the HO endonuclease nor on the amount of mating-type switching observed. Similarly, chromosomal deletion of all three ABF1-binding sites at HMR a had no effect on the directionality of mating-type switching.     

Bacterial interference by anaerobic species isolated from human feces

Eighty-four anaerobic fecal isolates obtained from five healthy volunteers were tested for their ability to inhibit in vitro growth of eight species of Enterobacteriaceae,four species of faculative gram-positive cocci, and Pseudomonas aeruginosa.Forty-nine of the 84 anaerobic isolates (58 %) inhibited the growth of at least one indicator bacterium. Isolates of Bacteroides and Bifidobacterium spp. were most consistently inhibitory. Anaerobic cocci and clostridia were infrequently inhibitory; eubacteria showed no inhibitory activity.Serratia marcescens was the indicator most often inhibited; 54 % of all anaerobic isolates tested, all of nine Bifidobacterium isolates and 33 of 43 Bacteroides isolates inhibited this organism. No anaerobes inhibited the growth of Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Citrobacter freundii, Citrobacter diversus orStreptococcus faecalis.     

Treatment of relapsingClostridium difficile diarrhoea by administration of a non-toxigenic strain

Two patients with relapsing Clostridium difficile diarrhoea following metronidazole and vancomycin therapy were colonised with a non-toxigenic avirulent Clostridium difficile strain given orally in three doses. Both patients appeared to respond without sideeffects. Oral bacteriotherapy with a defined nontoxigenic strain of Clostridium difficile would appear to represent an acceptable, alternative and novel way to treat hospitalised patients who relapse with Clostridium difficile diarrhoea after specific antibiotic therapy.     

Two-hour miniaturized system for detection of enteropathogenic bacteria in stool cultures

A miniaturized 2-h system for detection of lactosenegative potentially enteropathogenic bacteria on the basis of nine enzymatic tests was evaluated. The system was challenged with 210 strains of lactose-negative and lactose-positive species grown on MacConkey agar. Specific and constant patterns were found for Salmonella, Shigella A-C,Yersinia enterocolitica, Aeromonas spp. and Vibrio cholerae. Shigella sonnei and Hafnia alvei had an identical pattern, likewise Plesiomonas shigelloides,halophilic vibrios and Pseudomonas aeruginosa.     

Comparative in vitro activity of A-56268 (TE-031) against gram-positive and gram-negative bacteria andChlamydia trachomatis

The in vitro activity of A-56268 (TE-031) was determined and compared with that of 13 antibiotics against 401 gram-positive and gram-negative bacteria and 11 strains of Chlamydia trachomatis.A-56268 was very active against methicillin-susceptible Staphylococcus aureus and Neisseria gonorrhoeae,and was among the most active of the agents tested against Listeria monocytogenes,streptococci and Chlamydia trachomatis.It was moderately active against Haemophilus spp.,Vibrio spp.,Campylobacter jejuni and Campylobacter fetus subsp. fetus.It was inactive against enterococci, methicillin-resistant Staphylococcus aureus,Staphylococcus epidermidis, Campylobacter coli, Salmonella spp.,Shigella spp. and Yersinia enterocolitica.A-56268 was not consistently bactericidal or more active than erythromycin for any organism except Chlamydia trachomatis.     

In vitro activity of the two new 4-quinolones A56619 and A56620 againstNeisseria gonorrhoeae,Chlamydia trachomatis,Mycoplasma hominis,Ureaplasma urealyticum andGardnerella vaginalis

The in vitro activity of tetracycline, ciprofloxacin and two recently developed 1-aryl-fluoro-quinolones, A56610 and A56620, was tested against 65 beta-lactamase-negative and 35 betalactamase-positive Neisseria gonorrhoeae strains, 12 Chlamydia trachomatis,50 Mycoplasma hominis,28 Ureaplasma urealyticum and 50 Gardnerella vaginalis strains. In the case of Chlamydia trachomatis and Mycoplasma hominis both the MIC and the MBC were determined. The MIC90 of ciprofloxacin for Neisseria gonorrhoeae was 0.008 g/mland of A56619 and A56620 0.03 g/ml.No difference was observed between the activity against beta-lactamase-negative and beta-lactamase-positive strains. The MIC90 values of ciprofloxacin and A56620 for Chlamydia trachomatis, Mycoplasma hominis and Ureaplasma urealyticum were identical, the values being 2 g/ml, 1g/mland 4 g/mlrespectively. The MIC90 of A56619 for Chlamydia trachomatis and Ureaplasma urealyticum was 0.5 g/mland 1 g/mlrespectively. The MBC90 values of the three quinolones for Chlamydia trachomatis and Mycoplasma hominis were 2 g/ml.The activity of the quinolones against Gardnerella vaginalis was rather low, the MIC90 being 4 g/ml.It is concluded that A56619 and A56620 might be useful for single-dose therapy of gonococcal infections.     

Synergy of ciprofloxacin and azlocillin in vitro and in a neutropenic mouse model of infection

Combinations of ciprofloxacin with azlocillin, piperacillin and ticarcillin were tested in vitro against clinical isolates. Azlocillin plus ciprofloxacin showed synergy against 30% of Pseudomonas aeruginosa isolates; it was either synergistic or additive against 78% of all isolates tested even those resistant to the beta-lactam. Synergism was rarely noted for Klebsiella pneumoniae, Escherichia coli, Enterobacter spp. or Branhamella spp. isolates. Minimum inhibitory concentrations of ciprofloxacin plus azlocillin, plus piperacillin and plus ticarcillin against Pseudomonas spp. were reduced 4 or 2 fold, respectively. However, the combination azlocillin plus ciprofloxacin showed primarily indifference against gram-positive strains. Neutropenic mice infected with a lethal challenge of Pseudomonas spp. were protected by a combination of azlocillin and ciprofloxacin. Its additive and/or synergistic effects and expanded spectrum of activity against streptococci, methicillin-resistant staphylococci and JK corynebacteria may provide an alternative to traditional therapy.     

In vitro activity of amoxicillin plus clavulanic acid againstHaemophilus influenzae andBranhamella catarrhalis

The in vitro activity of amoxicillin in the presence of clavulanic acid against clinical isolates of Haemophilus influenzae and Branhamella catarrhalis was assessed in comparison with ampicillin, amoxicillin, cefaclor and erythromycin. The isolates were selected so as to yield equal numbers of beta-lactamase producing and non-beta-lactamase producing strains of the two species. MICs obtained by agar dilution indicated that amoxicillin in the presence of clavulanic acid was the most active of the drugs tested. Clavulanic acid potentiated the activity of amoxicillin against beta-lactamase-producing strains of both Haemophilus influenzae and Branhamella catarrhalis.Further studies on a few strains of each species revealed that the beta-lactamase of Haemophilus influenzae (TEM-1) rapidly inactivated ampicillin and slowly inactivated cefaclor but not cefuroxime. The Branhamella catarrhalis enzyme rapidly inactivated cefaclor, ampicillin and to some extent cefuroxime. Clavulanic acid afforded protection against the beta-lactamase action of both species when beta-lactam antibiotics were added to bacterial cultures.     

Emergence of beta-lactamase producing anaerobic bacteria in the tonsils during penicillin treatment

The emergence of beta-lactamase producing bacteria in the microflora in the oropharyngeal cavity was studied in ten healthy volunteers treated with 1 g phenoxymethylpenicillin b.i.d. for ten days. Beta-lactamase activity in saliva was also investigated. A significant increase in the number of beta-lactamase producing strains of Bacteroides species and Fusobacterium nucleatum was observed. One beta-lactamase producing Staphylococcus aureus strain was recovered in one of the volunteers before the penicillin administration started and three Staphylococcus aureus strains produced beta-lactamase after ten days of antibiotic treatment. Beta-lactamase-production in Haemophilus influenzae, Haemophilus parainfluenzae or Branhamella catarrhalis was not observed before, during or after the antibiotic treatment. Beta-lactamase activity was noted in the broth cultures from one volunteer colonized with a beta-lactamase producing Escherichia coli strain. Beta-lactamase activity in saliva was observed in all volunteers, the activity increasing significantly in parallel to the increase of betalactamase producing bacterial strains. Beta-lactamase activity in saliva was completely inhibited in vitro by clavulanic acid and p-chloromercurbenzoate and about 70–80 per cent of the activity was inhibited by cefoxitin. The increase of beta-lactamase producing bacteria in the oropharynx as a consequence of penicillin treatment raises doubt as to whether penicillin is the drug of choice in the treatment of tonsillitis caused by group A streptococci when previous treatment has failed.     

Beta-lactamase production in the upper respiratory tract flora

In order to determine the recovery rate of species of the genera Haemophilus and Moraxella (including subgenus Branhamella) from the upper respiratory tract and the incidence of -lactamase production within these genera, cultures were made of nose and throat swab specimens and adenoid tissue in 50 children undergoing adenoidectomy.Haemophilus influenzae was isolated from 92% of the children. All children harboured strains of Haemophilus spp. and in 46%, at least one strain produced the TEM-1 -lactamase.Branhamella catarrhalis and/or Moraxella nonliquefaciens were isolated from 82% of the children and strains producing the BRO-1 -lactamase from 34%. Overall, TEM-1 and/or BRO-1 producing strains were recovered from 60% of the investigated patients. The -lactamase production was found to be transferable by conjugation within the respective genera. It is suggested that the apathogenic species may be a source of transferable determinants mediating -lactamase production in the upper respiratory tract.     

In vitro activity and beta-lactamase stability of the oral cephalosporin BMY-28100

BMY-28100 was compared with cephalexin, cefaclor, cefixime, and cefteram and found to be more active than the reference cephalosporins against Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus faecalis,and Clostridium difficile.BMY-28100 was the next most active, after cefteram, against Streptococcus pyogenes and Streptococcus pneumoniae.Against gram-negative bacteria, BMY-28100 showed similar activity to that of cefaclor. The antimicrobial activity of BMY-28100, including bactericidal activity, against Staphylococcus aureus was less affected by penicillinase-production than was that of cefaclor. BMY-28100 was more stable than cefaclor against various types of penicillinases, especially against the penicillinase from Staphylococcus aureus.