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Biomedical subjects

A W Bruce

Publications and source records attributed to A W Bruce.

At least 19 recordsLinked to original sources
PubMed1995

Effects of ciprofloxacin and vancomycin on physicochemical surface properties of Staphylococcus epidermidis, Escherichia coli, Lactobacillus casei and Lactobacillus acidophilus.

Under clinical conditions, during antibiotic treatment, micro-organisms often grow at sub-inhibitory concentrations. This may lead to altered adhesive cell surface properties and to a disruption of the indigenous microflora, in addition to the creation of a more pathogenic biofilm. The effects of growing Staphylococcus epidermidis, Escherichia coli and lactobacilli in the presence of sub-inhibitory concentrations of ciprofloxacin and vancomycin were determined. Growing the cells under antibiotic burden sometimes led to altered cell surface hydrophobicity (by adhesion to hexadecane), changes in the pH-dependence of zeta potentials, and elemental surface compositions or in different SDS-PAGE protein profiles. For several isolates only one of the surface properties was altered by the presence of an antibiotic in the growth medium and no systematic effects were observed for all isolates representing a certain species or even strain. The important conclusion to be drawn from the results of this study is that the effects of growing cells under antibiotic burden on their adhesive cell surface properties can only be established when using a variety of techniques.

Alkanes↗
PubMed1994

Adhesion of lactobacilli to urinary catheters and diapers: effect of surface properties.

Thirteen strains of lactobacilli were tested for their ability to adhere to commercial devices used in the urinary tract. Although it appeared that the most hydrophilic organisms adhered in highest numbers, there was no significant correlation between water contact angle and adhesiveness to catheters. Five organisms tested were found to be highly adherent to Huggies commercial diapers. Loss in hydrophobicity upon serial culture of Lactobacillus fermentum B-54 was not due to a proteinaceous S layer, although protein involvement per se cannot be ruled out. It was evident that, not only can members of the normal female urogenital flora adhere to commonly used commercial prostheses, but their ability to attach is related to hydrophilic as well as hydrophobic surface components.

Adult↗
PubMed1994

Effects of ciprofloxacin, norfloxacin, and ofloxacin on in vitro adhesion and survival of Pseudomonas aeruginosa AK1 on urinary catheters.

Pretreatment of urinary silicone latex catheters in vitro with 0.1 and 0.5 microgram of ciprofloxacin per ml for 1, 24, and 48 h significantly reduced the adhesion and survival of the clinical isolate Pseudomonas aeruginosa AK1. UV spectroscopy and high-performance liquid chromatography confirmed the presence of ciprofloxacin adsorbed onto the catheters and showed that up to 56% of the drug leached into the surrounding fluid within 24 h. Scanning electron microscopy demonstrated that the adherent organisms were malformed and elongated after exposure to ciprofloxacin. Transmission electron microscopy showed the presence of fimbriae on the bacterial surfaces, but there was no conclusive evidence of changes in the fimbriae upon exposure to ciprofloxacin. It was found that a significant eradication of 24-h Pseudomonas biofilms could be achieved with ciprofloxacin as well as with ofloxacin and norfloxacin. Preincubation of catheters with 50- and 100-micrograms/ml concentrations of ciprofloxacin resulted in up to a 99% reduction in the number of adherent bacteria in comparison with the reduction on control catheters. In addition, adherent biofilms were eradicated by 24 h of challenge with 50 and 100 micrograms of ciprofloxacin per ml at pH 7.0 and 5.5. Results of these in vitro studies suggest that there could be a clinical role for fluoroquinolones in preventing and treating urinary tract infections associated with P. aeruginosa adherence to prosthetic devices.

Anti-Infective Agents↗
PubMed1993

Adhesion of three Lactobacillus strains to human urinary and intestinal epithelial cells.

Three strains of urogenital lactobacilli were found to adhere in phosphate buffered saline to human uroepithelial cells in vitro according to thermodynamic principles, and to adhere in culture medium to intestinal cells with no such correlation. The most hydrophilic strain (water contact angle 54 degrees) L. casei RC-17 was the most adherent to uroepithelial (118 bacteria per cell) and intestinal cells (165 bacteria per cell). A direct correlation was found between bacterial hydrophilicity and adhesion to uroepithelial cells for the three strains tested. An extracellular adhesin, which appeared to be proteinaceous, and a trypsin-insensitive cell wall adhesin were identified. It was evident that high levels of bacterial retention could be reproduced in vitro, perhaps indicating the potential colonizing capacity of these strains in vivo.

Adult↗
PubMed1992

Correlation between hydrophobicity and resistance to nonoxynol-9 and vancomycin for urogenital isolates of lactobacilli.

Seven clinical isolates of lactobacilli were found to be relatively hydrophobic with a mean water-contact angle of 66 +/- 15 degrees, and to be susceptible to 1% nonoxynol-9 and vancomycin. However, seven other strains were relatively hydrophilic with a mean water-contact angle of 32 +/- 13 degrees, and found to be resistant to 25% nonoxynol-9 and vancomycin. Thus, the surface properties of lactobacilli that influence susceptibility to antimicrobial agents may involve surface hydrophobicity. Possibly the penetration barrier posed by the cell surface towards these two nonionic antimicrobials is lower for hydrophobic cells than for hydrophilic cells.

Adult↗
PubMed1992

Antibiotic resistance of urinary pathogens isolated from patients attending the Toronto Hospital between 1986 and 1990.

A study was carried out on 1523 urinary isolates obtained at The Toronto Hospital, Canada's largest tertiary care establishment, over three 1-month periods in 1986, 1987 and 1990. Escherichia coli was the most frequently isolated organism, with Enterococcus spp. the second most common isolate in 1986 and 1987, and Streptococcus spp. in 1990. Pseudomonas aeruginosa isolates were found to be resistant to many of the antimicrobial agents tested. Resistance patterns were found to commonly prescribed ampicillin, co-trimoxazole and, to some extent, the new fluoroquinolones, ciprofloxacin and norfloxacin. These results are relevant to the treatment and management of urinary tract infections in patients attending a tertiary care hospital.

Cross Infection↗
PubMed1992

Hydrogen peroxide production by Lactobacillus species: correlation with susceptibility to the spermicidal compound nonoxynol-9.

Facultative anaerobic lactobacilli were recovered from the vaginas of 96.8% of 63 nonpregnant, healthy, premenopausal women. The predominant species were Lactobacillus jensenii, Lactobacillus acidophilus, and Lactobacillus casei. Of the women, 74.6% had hydrogen peroxide-producing lactobacilli, 22.2% had non-hydrogen peroxide-producing lactobacilli, and 3.2% had no lactobacilli. None of the 68 isolates had catalase activity. Some 68.2% of the isolates were inhibited by concentrations of less than or equal to 1% (wt/vol) of nonoxynol-9 (bactericidal for 73.3% of isolates, bacteriostatic for 26.7%). The remaining 31.8% could grow in all concentrations to 25% (wt/vol) of nonoxynol-9. All of the lactobacilli that were sensitive to nonoxynol-9 produced hydrogen peroxide whereas only 3 of 21 resistant strains were hydrogen peroxide producers. A significant correlation (P less than .001, chi 2 test) was found between hydrogen peroxide production and sensitivity to nonoxynol-9. It is suggested that the vaginal flora of spermicide users could be depleted of hydrogen peroxide-producing lactobacilli, possibly increasing susceptibility to urogenital infection.

Adult↗
PubMed1992

Comparison of contact angles and adhesion to hexadecane of urogenital, dairy, and poultry lactobacilli: effect of serial culture passages.

The aim of this study was to examine the hydrophobicities of 23 urogenital, dairy, poultry, and American Type Culture Collection isolates of lactobacilli and to determine the effect on hydrophobicity of serially passaging the strains in liquid medium. To this end, strains were grown after isolation and identification and then serially passaged up to 20 times. Hydrophobicity was assessed through contact angle measurements on lawns of cells by using water, formamide, methylene iodide, 1-bromonaphthalene, and hexadecane as wetting agents and through measurement of their partitioning in a hexadecane-water system. The hydrophobicities of these strains varied widely, with Lactobacillus casei strains being predominantly hydrophilic and L. acidophilus strains being mostly hydrophobic. For some isolates, serial passaging was accompanied by a clear loss of hydrophobic surface properties, whereas for other strains, cultures became heterogeneous in that some cells had already lost their hydrophobic surface properties while others were still hydrophobic. Adhesion of this collection of lactobacilli to hexadecane droplets in microbial adhesion to hexadecane (MATH) tests was driven by their aversion to water rather than by their affinity for hexadecane, as concluded from the fact that hexadecane contact angles were zero for all strains. Furthermore, adhesion of the lactobacilli to hexadecane in MATH tests occurred only when the water contact angle on the cells was above 60 degrees.

Adult↗
PubMed1991

Ability of uropathogens to bind to Tamm Horsfall protein-coated renal tubular cells.

Epithelial cells were isolated from a healthy human kidney and found to be of normal, renal tubular origin. The cells were maintained in tissue culture and found to secrete Tamm Horsfall protein (THP). Three strains of uropathogenic Escherichia coli, and one each of Proteus mirabilis and Pseudomonas aeruginosa were found to adhere to the THP-coated tubular cells. Extraneous THP bound to all the organisms except P fimbriated E. coli, and caused a reduction in the adhesion of type 1 fimbriated E. coli and P. mirabilis to the renal cells. However, irrespective of reduced adhesion in three of five strains tested, there was adequate evidence to indicate that THP does not competitively exclude all uropathogenic adhesion. On the contrary, its presence on renal cells may act to mediate bacterial colonization.

Bacterial Adhesion↗
PubMed1990

Effect of extracorporeal shock wave lithotripsy on bacterial viability. Relationship to the treatment of struvite stones.

The aim of this study was to determine whether extracorporeal shock wave lithotripsy (ESWL) affected the viability of the infecting bacteria within a simulated struvite stone matrix. A strain, Proteus mirabilis 28cii, was prepared in three forms: (1) suspended in saline and urine, (2) artificially encapsulated by suspending in agar beads and (3) artificially encapsulated and mineralised by suspending in agar beads with calcium carbonate crystals. The preparations were placed in capped vials partially immersed in degassed water and held in the focal point of the Siemens Lithostar and given 1,000 shocks. Subsequent viability testing showed that bacteria suspended in urine were greatly affected by shock treatments (55% loss in viability), but incorporation into agar beads negated this effect (even if the cells were exposed to 2000 shocks). Mineralisation of the beads with calcium carbonate crystals caused a decrease in viability of 82% that was significantly different from controls. However, this still left 2.3 X 10(8) viable organisms (82% of 2.8 X 10(8], easily enough to form the focus for further infections. A series of control experiments carried out using an ultrasonic cell sonicator probe gave comparable results to those obtained with ESWL. These results demonstrate the ESWL treatment of infected stones must be accompanied by antimicrobial coverage.

Humans↗
PubMed1990

Is there a role for lactobacilli in prevention of urogenital and intestinal infections?

This review describes the importance of microbial adhesion in the ecology of the urogenital and intestinal tracts and the influence of host and microbial factors in bacterial interference. In a recent revival of interest in bacterial interference, lactobacillus administration has been studied as a means of treating and preventing disease. Although evidence is conflicting, Lactobacillus acidophilus appears to be involved in beneficial antagonistic and cooperative reactions that interfere with establishment of pathogens in the gastrointestinal tract. The mechanisms of action are believed to involve competitive exclusion and production of inhibitory substances, including bacteriocins. These characteristics, as well as demonstrated adherence abilities in vitro, led to selection of certain Lactobacillus strains for clinical studies of cystitis. Weekly intravaginal Lactobacillus therapy reduced the recurrence rate of uncomplicated lower urinary tract infections in women. Use of Lactobacillus strains resistant to Nonoxynol-9, a spermicide that kills members of the protective normal vaginal flora, may have potential for use in women with recurrent cystitis using this contraceptive agent. In veterinary studies, bacterial interference by administration of probiotics has also been beneficial in disease prevention in animals. Carefully selected bacterial mixtures integrate with the gastrointestinal flora of the animals and can confer disease resistance and improve physiological function. Additional human and animal trials are needed to determine the practical, long-term usefulness of bacterial interference as a protective mechanism against infectious diseases.

Bacterial Physiological Phenomena↗
PubMed1990

The spermicidal compound nonoxynol-9 increases adhesion of Candida species to human epithelial cells in vitro.

All 25 strains of Candida spp. tested were able to grow in medium supplemented with 25% nonoxynol-9 in vitro. Adhesion of Candida spp. to HeLa cells was found to increase in the presence of 5% nonoxynol-9 (2.2- to 6.6-fold; P less than 0.001) and, to a lesser extent, in 12.5% nonoxynol-9. Adhesion of Candida strains cultured in medium supplemented with nonoxynol-9 varied, with five of six strains of Candida albicans and the single strain of Candida tropicalis demonstrating increases of 1.4 to 4.0 times control levels (P less than 0.05). The increased adhesion did not correlate with altered yeast cell surface hydrophobicity or germ tube formation.

Adhesiveness↗
PubMed1990

Effect on urogenital flora of antibiotic therapy for urinary tract infection.

Specimens were examined from 70 female presenting with urinary tract infection. 50 patients were randomly treated with 7 days amoxicillin or bacampicillin and another 20 randomly received amoxicillin or enoxacin. Effective clearance of the infections was achieved with each antibiotic, and only minor side effects occurred. Bacteriological analyses of the urogenital flora demonstrated a relationship between urethral carriage and bladder infection, with Escherichia coli being the most common pathogen. Antibiotic resistant E. coli were isolated more frequently from the bladder, urethra, introitus and rectum following amoxicillin treatment compared to bacampicillin and enoxacin. An examination of the urogenital flora post therapy showed that an indigenous lactobacillus population had not been restored in the majority of patients. Rather, uropathogenic bacteria were found to dominate the urethra and introitus. The effects of antibiotics on urogenital flora is clearly a matter of importance. Future clinical trials should address this. It may be that artificial supplementation of indigenous bacteria is necessary to restore the flora back to normality.

Adolescent↗
PubMed1990

Bacterial aggregation in relation to peritoneal dialysis.

The ability of gram-positive cocci to aggregate and form biofilms at the exit site and on catheter surfaces in continuous ambulatory peritoneal dialysis (CAPD) has been associated with peritonitis. In the present study, 16 (80%) of 20 dialysate effluents from patients with staphylococcal peritonitis were found to contain aggregates of Staphylococcus epidermidis or S. aureus. Using an in vitro assay system, 20 (83%) of 24 pathogenic bacterial strains were found to aggregate in fresh dialysis solutions within 4 to 24 h at 37 degrees C. Further studies with one strain, S. epidermidis 1938, showed increased aggregation when the bacteria were incubated in dialysate effluents compared to fresh dialysis solutions. Viability experiments showed that aggregated bacteria were less sensitive to the killing effects of fresh dialysis solutions and that dialysate effluents could support bacterial growth. The results suggest that attention be paid to aggregation as a potential mechanism used by bacteria in causation of peritonitis.

Bacterial Adhesion↗
PubMed1989

Prostatitis associated with Chlamydia trachomatis in 6 patients.

A number of studies have shown that Chlamydia trachomatis bacteria are important pathogens in urogenital tract infections, such as acute urethritis, acute epididymo-orchitis in male patients and pelvic inflammatory disease in female patients. We confirm a previously reported association between Chlamydia trachomatis and prostatitis. We report on 6 patients with definitive confirmation via tissue culture and an immunofluorescent technique. The results demonstrate that chlamydial prostatitis occurs in patients with nonbacterial disease. Efforts should be made to detect and eradicate the organisms from the prostate.

Adult↗