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Biomedical subjects

T S Elliott

Publications and source records attributed to T S Elliott.

At least 73 records · Page 4Linked to original sources
PubMed1993

The effects of electric current on bacteria colonising intravenous catheters.

The effect of a direct electric current (10 microA) on the growth of Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis was investigated. When the ends of negatively-charged intravascular catheters were placed in nutrient agar seeded with bacteria, circular zones of inhibition of bacterial growth were observed around the catheters. The zones ranged from 6 to 16 mm in diameter according to the organism under test. Zones of inhibition were not produced around positively-charged catheters. Bacteria colonising the surfaces of catheters were similarly affected by the application of a 10 microA electric current. A negative electric current applied to colonised catheters for 4 to 24 h significantly reduced the number of adherent viable organisms as compared to controls. The results demonstrated that a constant electric current of low amperage might be used to reduce bacterial colonisation of intravascular catheters. This may offer a novel means of protecting catheters and other prosthetic devices from associated sepsis in vivo.

Bacterial Adhesion↗
PubMed1993

Monitoring of hospital water supplies for Legionella.

In order to determine the value of regular surveillance for Legionella in the prevention of hospital-acquired (nosocomial) legionellosis, water samples were obtained over a three-year period from 17 hospitals located in England and Scotland. Prior to the study, all of the hospitals had in operation defined protocols and maintenance schedules which followed national guidelines for the prevention of legionellosis in health care premises. Six samples, from key locations in the water system of each hospital, were taken at six-monthly intervals. Total viable bacterial count (TVC), coliform count and legionella cultures were performed on all the samples. No coliforms were detected in any of the samples, whereas the TVC was variable. Legionella pneumophila was isolated from both the hot and cold water supplies of two hospitals. The TVC was not related to the isolation of Legionella. Confirmation of the presence of Legionella was subsequently attributed to defects in the equipment and water maintenance programmes. It was concluded that the microbiological examination of water is an effective approach to the audit of the maintenance of hospital water systems in order to prevent legionellosis.

Colony Count, Microbial↗
PubMed1993

A novel antimicrobial central venous catheter impregnated with benzalkonium chloride.

Catheter-related sepsis is a common complication associated with the use of central venous catheters (CVC). In an attempt to overcome this problem benzalkonium chloride was incorporated into a CVC polymer. The effect of the presence of benzalkonium chloride on microbial colonization of the CVC was then assessed in vitro. MICs and MBCs of benzalkonium chloride for a range of organisms were performed and good activity against Gram-positive organisms was confirmed. In order to assess the antimicrobial activity of the benzalkonium-chloride-impregnated catheter, 2 cm lengths were placed on to nutrient agar plates inoculated with various micro-organisms. Zones of inhibition against five strains of Staphylococcus epidermidis and two strains of Staphylococcus aureus were demonstrated. Smaller zones of inhibition was also produced with Gram-negative species and Candida albicans. The zone sizes correlated with the MICs. Bacterial adherence to the benzalkonium-chloride-impregnated catheters was determined in both static and dynamic models and was significantly reduced compared with control catheters, containing no antimicrobial agent (P < 0.01). Inhibition of microbial adherence to benzalkonium-chloride-impregnated catheters placed in 25% human blood in phosphate-buffered saline (PBS), for up to seven days or PBS alone for 14 days was detected. The findings indicate that benzalkonium-chloride-impregnated catheters exhibit reduced microbial colonization by a range of organisms in vitro. The incorporation of benzalkonium chloride into a CVC may thus offer an effective method for the prevention of catheter related sepsis.

Bacteria↗
PubMed1993

Microbial colonization of Blom-Singer prostheses in postlaryngectomy patients.

The microbial colonization of 44 Blom-Singer valves obtained from 16 patients over an 11-month period was investigated both by standard microbial culture methods and scanning electron microscopy (SEM). The valves were all removed from the patients after failure to function correctly. The microbiology cultures revealed that Candida species and Staphylococcus aureus were present either individually or in combination on 43 valves. SEM showed yeast hyphae attached to and penetrating the surfaces of the 5 valves examined. Colonies of staphylococci were also seen on 2 of these 5 valves. Unlike similar investigations on other voice prostheses, S aureus colonization was associated with Candida colonization and valve failure.

Candida↗
PubMed1992

A novel electrical method for the prevention of microbial colonization of intravascular cannulae.

An electrical device designed to prevent microbial attachment to plastic intravascular cannulae is described. The device produced an electrical current (10 microA) in both carbon-impregnated and 'Hydrocath' cannulae. In-vitro models were utilized to demonstrate that the current can block several mechanisms by which microorganisms gain initial access to intravascular devices, including extra- and intra-luminal routes. The electrical system prevented organisms from traversing along both the external and internal surfaces of the cannulae. Effective prevention of cannula colonization was demonstrated subsequent to challenge with Staphylococcus epidermidis, Staphylococcus aureus, Enterococcus faecalis, Proteus mirabilis, Pseudomonas aeruginosa and Candida albicans. The findings suggest that the electrical device may offer in-vivo cannula protection from microbial attachment and colonization, thereby reducing the potential for infection.

Bacterial Adhesion↗
PubMed1992

Pigeons and peritonitis?

We report an outbreak of fungal peritonitis due to Candida parapsilosis in 12 patients undergoing chronic ambulatory peritoneal dialysis (CAPD). All 12 patients were treated by removal of the CAPD catheter together with systemic antifungal therapy. There were no peritonitis-related deaths. Four patients were successfully returned to CAPD at a later date. Microbiological investigation during the outbreak demonstrated colonization of various areas of the CAPD Unit and medical ward with the organism. C. parapsilosis was also isolated from pigeon guano obtained from window-sills. The number of cases of peritonitis due to this organism decreased markedly after bird-proof netting was installed. We believe that this is the first report of an outbreak of CAPD peritonitis due to faecal carriage of C. parapsilosis by pigeons.

Adult↗
PubMed1990

Identification of flagellar and associated polypeptides of Helicobacter (formerly Campylobacter) pylori.

Flagella of Helicobacter pylori were isolated from intact organisms by shearing and differential centrifugation. Treatment of the flagella with the detergent Triton X-100 removed the flagellar sheath, which was confirmed by electron microscopy, and the remaining naked flagella were shown by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) to consist primarily of a single 54 kilodalton (kDa) polypeptide. This was confirmed by immunogold labelling and electron microscopy of detergent treated whole organisms, using a mouse antiserum specific for the 54 kDa polypeptide. Polypeptides solubilised from crude flagellar preparations by detergent treatment were found to have molecular weights of 26, 30, 58, 62, 66 and 80 kDa. These polypeptides are possible components of the flagellar sheath and they may represent outer membrane proteins, based on the assumption that the flagellar sheath is related in composition to the outer membrane of the organism. Analysis and definition of these components of the surface structures of the organism are important in understanding the interaction between the organism and its host in pathogenesis.

Bacterial Proteins↗
PubMed1990

The effect of antibiotics that inhibit cell-wall, protein, and DNA synthesis on the growth and morphology of Legionella pneumophila.

The response of Legionella pneumophila to antibiotics that inhibit cell-wall, protein and DNA synthesis was examined by electronmicroscopy, MIC estimations and viable counts. Ampicillin, cefotaxime, methicillin, erythromycin, rifampicin and ciprofloxacin, each used separately at 20 times their respective MIC values, showed activity against L. pneumophila in these studies. The inhibitors of cell-wall synthesis--ampicillin, cefotaxime and methicillin--effected the greatest bactericidal activity and induced the most extensive morphological changes, which included the formation of membranous lesions through which cytoplasmic contents were lost. In terms of ultrastructural damage and loss of viability, the inhibitors of protein and DNA synthesis were less effective than the antibiotics that acted on the microbial cell wall. Erythromycin- and rifampicin-treated cells possessed irregular membranes and were partially or fully lysed, whereas ciprofloxacin induced abnormally elongated organisms with intermittently lysed and detached inner membranes. These results illustrated the ability of antibiotics of putative clinical value, with diverse modes of action, to affect the ultrastructural cytology as well as the viability of L. pneumophila in vitro.

4-Quinolones↗
PubMed1990

The pathogenesis of urinary tract infections associated with Escherichia coli, Staphylococcus saprophyticus and S. epidermidis.

A model was developed in mice to study the pathogenesis of urinary tract infections caused by Staphylococcus saprophyticus strains LM-1 and LM-2, Escherichia coli SP444 and S. epidermidis E001. Murine urinary bladders were inoculated with 10(8) bacteria via a temporary urinary catheter and samples of urine and bladder were removed at days 1, 3, 5 and 10 after inoculation. They were examined both bacteriologically and by electronmicroscopy. Severe disruption of the urothelium was present immediately and the urothelium had become oedematous and ulcerated with increased urothelial exfoliation. Disruption of the urothelium was similar with all the four pathogens studied. The three strains of coagulase-negative staphylococci preferentially attached to the urothelial cell tight junctions and were not associated with polymorphonuclear leucocytes. In comparison, E. coli SP444 was randomly attached over the entire urothelium and was often in association with macrophages. Phagocytosis of E. coli by superficial urothelial cells also occurred.

Animals↗
PubMed1990

Review article: metronidazole and the anaerobic gut flora.

Metronidazole is a nitro-imidazole drug which was discovered nearly 30 years ago. Metronidazole has remained the mainstay of anti-anaerobic therapy following a change observation that its activity included anaerobic organisms. The predominant human reservoir of these anaerobic organisms is the gastrointestinal tract. In this review, the anaerobic flora and their pathogenic potential are described. The main characteristics of metronidazole and the role of selective decontamination of the gastrointestinal tract are also discussed.

Animals↗
PubMed1989

Effects of heparin and chlorbutol on bacterial colonisation of intravascular cannulae in an in vitro model.

An in vitro model was used to study the effects of heparinised saline, with or without the preservative chlorbutol, on the colonisation of intravascular cannulae. Chlorbutol significantly reduced cannula colonisation by Staphylococcus epidermidis. Flushing colonised cannulae with heparinised saline plus chlorbutol significantly reduced the number of organisms adhering to the inner surface of cannulae, when compared with the use of heparinised saline without preservative. Chlorbutol-preserved heparinised saline may not only maintain cannula patency by the prevention of thrombus formation, but may also reduce the incidence of bacterial colonisation of cannulae in vivo.

Bacterial Infections↗
PubMed1989

Are ECG Welsh cup electrodes effectively cleaned?

Re-usable Welsh electrocardiograph (ECG)-electrodes are potential vehicles for cross infection. This study confirmed that in-use ECG-electrodes are frequently contaminated with organisms such as coagulase-negative staphylococci and Gram-negative bacilli. The efficacy of five cleaning procedures was evaluated. Immersing the electrodes in water at 60 degrees C for one hour was the most effective method of decontamination tested, following challenge with a standardised suspension of Staphylococcus saprophyticus. Significant contamination persisted following simple cleaning measures. It is suggested that this was promoted by the inadequate removal of electrode gel which provided a protective environment for microorganisms.

Chlorhexidine↗
PubMed1989

Is resistance to novobiocin a reliable test for confirmation of the identification of Staphylococcus saprophyticus?

Staphylococcus saprophyticus, a coagulase-negative staphylococcus (CNS), causes acute urinary tract infection predominantly in young women (15-30 years). In the clinical microbiology laboratory identification and differentiation of S. saprophyticus from other CNS usually depends solely upon the demonstration of resistance to the antimicrobial agent novobiocin. Phenotypic characteristics of 36 novobiocin-resistant CNS isolated from the urine of patients with acute urinary tract infections were further analysed and the homogeneity of the isolates assessed. The organisms were speciated by the API STAPH identification system. Twenty-one isolates were S. saprophyticus (p greater than or equal to 97%), and there was one strain each of S. epidermidis, S. hominis and S. simulans (p greater than or equal to 97%). Of the remainder, three isolates were unidentifiable and a further nine had the characteristics associated with more than one species of CNS. Additional tests, including carbohydrate fermentation, antibiotic sensitivity and fluorogenic substrate utilisation, were performed on all isolates. Computer analysis of the results confirmed that testing for resistance to novobiocin selects a heterogeneous group of CNS composed of several different species.

Adolescent↗
PubMed1989

Bladder irrigation or irritation?

Exfoliation rates of urothelial cells following bladder irrigation were studied in patients with long-term indwelling catheters and chronic urinary tract infections (UTI). The irrigations were associated with an increased shedding of urothelial cells. Ultrastructural studies of these cells demonstrated increased disruption when compared with those obtained from normal subjects without catheters or chronic infection. The findings suggest that bladder irrigation further damages the already disrupted urothelium, which may in turn increase the predisposition of the bladder to the recurrent infections, commonly associated with patients who have indwelling urinary catheters. Bladder irrigation methods and the indications for their use require reassessment.

Aged↗