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Biomedical subjects

M H Wilcox

Publications and source records attributed to M H Wilcox.

At least 109 records · Page 6Linked to original sources
PubMed1994

Assessment of a chemiluminescent universal probe for taxonomical and epidemiological investigations of Aeromonas sp isolates.

AIMS: To assess a chemiluminescent universal probe for taxonomical and epidemiological investigations of Aeromonas sp isolates. METHODS: Total DNA was extracted from 69 well characterised Aeromonas sp strains and digested with the restriction endonucleases Sma I or Pst I. Following electrophoresis, the resulting fragments were transferred to a nylon membrane where they were hybridised to a commercially available universal probe of 16S + 23S rRNA. The banding patterns (ribotypes) were made visible by enhanced chemiluminescence. RESULTS: Both restriction endonucleases produced heterogeneous ribotypes so that no allocation could be made to any of the control genospecies tested. For A hydrophila and A caviae, however, groups of strains (mostly from the same patient) could be identified by indistinguishable banding patterns. A relatively high proportion (36%) of A sobria strains were non-typable. CONCLUSIONS: Although this universal chemiluminescent probe is user friendly, it is unsuitable for taxonomical investigations of Aeromonas sp. It is useful in epidemiological studies of A hydrophila and A caviae, but is of less value for A sobria.

Adult↗
PubMed1993

Retained Hickman catheter cuff as a source of infection.

Two cases of Pseudomonas aeruginosa infection complicating retained subcutaneous Hickman catheter cuffs are described. Foreign body-associated Pseudomonas infection is unlikely to respond to treatment with antibiotics alone. We therefore recommend that the cuff is removed at the same time as the Hickman catheter is pulled out so as to prevent future infection.

Adult↗
PubMed1993

The efficacy of a hospital dry cleaning cycle in disinfecting material contaminated with bacteria and viruses.

It is not known how efficiently a standard dry cleaning cycle can kill bacteria or viruses. In-situ experiments were carried out to determine the cidal activity of such a cycle using perchloroethylene solvent against five clinical bacterial isolates and a DNA bacteriophage. Viable counts of bacteria recovered from material after dry cleaning were reduced by 3-8 logs, with up to 10(3) colony forming units (cfu) surviving per strip. Numbers of bacteriophage were only reduced by 10-100 fold. The resistance of the bacteriophage to solvent and heat (60 degrees C) was compared with that of polio and herpes simplex viruses in vitro. Polio virus and bacteriophage, but not herpes simplex virus, survived exposure to perchloroethylene at room temperature for 40 min. Dry cleaning with perchloroethylene is not bactericidal and is particularly poorly virucidal for non-enveloped viruses.

Bacteria↗
PubMed1993

Susceptibility of alpha-haemolytic streptococci causing endocarditis to benzylpenicillin and ten cephalosporins.

A clinical case of streptococcal endocarditis in which the isolate proved susceptible to third- but not first-generation cephalosporins prompted us to examine the susceptibility of 44 alpha-haemolytic streptococci from cases of endocarditis to ten cephalosporins and benzylpenicillin. Twenty per cent of strains were resistant to penicillin, and 20% were tolerant. Cefazolin, cefuroxime and cefpirome were the most active first-, second- and third-generation cephalosporins tested. Other first-generation cephalosporins tested compared poorly to cefazolin. Cefotaxime and cefpirome were moderately active against some penicillin-resistant strains. Penicillin tolerance was common in Streptococcus gordonii, but a correlation between tolerance and dextran production could not be confirmed.

Cephalosporins↗
PubMed1993

Lignocaine spray applicators are a potential source of cross-infection in the anaesthetic room.

Ten percent lignocaine spray is in widespread clinical use as a means of suppressing responses to tracheal intubation. It is sprayed from a multidose container into the glottis and on to the vocal cords through an applicator nozzle, which may be used on successive patients. We have investigated the likelihood of the contamination of these nozzles, with patients' mouth flora. Spray applicators from four of the 20 cases investigated showed contamination with potential bacterial pathogens. We therefore recommend that lignocaine spray should not be applied to successive patients using the same applicator nozzle.

Adolescent↗
PubMed1993

The slime of coagulase-negative staphylococci: biochemistry and relation to adherence.

In recent years, infections of implanted plastic devices by coagulase-negative staphylococci have become a major cause of septicaemia in human patients. The causal bacterial species is usually Staphylococcus epidermidis and these organisms grow as a biofilm adherent to a solid surface. Several methods have been introduced to assess the mass of adherent bacteria and the slimy matrix in which they are embedded. Some methods measure total biofilm, others measure the organisms or the slime alone. In vitro, the type of medium, the atmosphere during incubation, and the nature of the solid surface, affect the quantity of biofilm that is formed. In most studies on the chemistry of the slime, the material used was formed on complex media solidified with agar. Contamination by ingredients of the media or by agar may not always have been recognised. Recent work with chemically defined medium (liquid or solidified with silica gel) shows that the slime is a mixture of about 80% (w/w) teichoic acid and 20% protein. Growth as a biofilm may protect the staphylococci from antibiotics. At present, the greatest success in preventing infection has come from improved surgical techniques during the insertion of implants.

Bacterial Adhesion↗
PubMed1993

Toxoplasma infection and systemic lupus erythematosus: analysis of the serological response by immunoblotting.

AIMS: To examine the serological response of patients with systemic lupus erythematosus (SLE) and toxoplasma infection and to compare the blot profiles with those from immunocompetent subjects of similar immune response. METHODS: Forty serum samples from patients with SLE were tested for toxoplasma antibodies using the dye and indirect haemagglutination tests. Specific IgM was measured by mu-capture enzyme linked immunosorbent assay (ELISA). The sera were immunoblotted using antigen strips prepared from the RH strain of Toxoplasma gondii. For comparison, control blots were prepared from pooled sera from immunocompetent subjects with serological evidence of acute (pool 1), or chronic (pool 2) toxoplasma infection, or with no evidence of infection (pool 3). RESULTS: Some of the blot profiles from the patients with SLE were compatible with the corresponding serology but others showed considerable variation, particularly among the IgM blots. The blots from sera with low dye test titres suggested that the latter could be false positive results. CONCLUSIONS: Toxoplasma infection may enhance the production of autoantibodies which, when combined with the high titres characteristic of SLE, might interfere in the dye test and other serological tests. Immunoblotting could prove useful in the immunocompromised for confirming the presence of specific toxoplasma antibodies and for the staging of infection in those with positive serology.

Animals↗
PubMed1992

Importance of medium and atmosphere type to both slime production and adherence by coagulase-negative staphylococci.

Marked differences in both the production of slime and adherence by Staphylococcus epidermidis were observed when comparing four culture media. Slime isolated from a strain cultured in a chemically defined medium (HHW) in air was chemically indistinguishable from that formed in both HHW and synthetic dialysis fluid (SDF) in air with 5% CO2. The presence of a physiological level of CO2 during culture in tryptone soya broth (TSB) prevented production of slime. It was not possible to separate the constituents of slime from those of the culture medium in bacteria grown in TSB in air using DEAE cellulose. Slime production was notably poor in used peritoneal dialysis fluid (PUD). Adherent growth was marked in HHW and SDF but was poor in TSB and PUD when air with 5% CO2 was used. These findings emphasize the advantages in using chemically defined and biological fluids when studying slime production and adherence by S. epidermidis.

Bacterial Adhesion↗
PubMed1992

Clostridium difficile infection: responses, relapses and re-infections.

Clostridium difficile infection is a common and potentially lethal complication of antibiotic usage. Since the aetiology of antibiotic-associated colitis was discovered 14 years ago, two antibiotics in particular, metronidazole and vancomycin, have been used to treat C. difficile infection. Studies comparing the efficacy of these antibiotics are reviewed. It is now apparent that many of the so-called 'relapses' of C. difficile infection following antibiotic treatment are, in fact, re-infections. Such findings have major infection control implications.

Clinical Trials as Topic↗
PubMed1992

In-vitro activity of imipenem, in comparison with cefuroxime and ciprofloxacin, against coagulase-negative staphylococci in broth and peritoneal dialysis fluid.

The activity of cefuroxime, ciprofloxacin and imipenem against 50 coagulase-negative staphylococci (CNS) strains isolated from patients with peritonitis while on continuous ambulatory peritoneal dialysis (CAPD) was examined. Strains were cultured in both used peritoneal dialysis fluid (PUD) and broth (ISB) in an atmosphere of air with 5% CO2. MICs of cefuroxime, ciprofloxacin and imipenem differed significantly between the two media for 40%, 26% and 42% of strains, respectively. In three-quarters of these cases the MICs were higher in PUD compared to ISB. The ability of each antibiotic to kill six strains of CNS adherent to silicone rubber was also examined. Once again, differences in killing were noted between the two media. At least two-thirds of the strains remained viable in the presence of concentrations of antibiotic equal to the MBC of each antibiotic and at least one-third survived antibiotic concentrations equivalent to those attained during treatment. Assessment of activity in PUD may provide a more realistic test for antibiotics to be used in the treatment of CAPD peritonitis.

Cefuroxime↗