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Biomedical subjects

M H Wilcox

Publications and source records attributed to M H Wilcox.

At least 55 records · Page 3Linked to original sources
PubMed2000

Hospital disinfectants and spore formation by Clostridium difficile.

Evidence is lacking on how best to decontaminate the hospital environment of Clostridium difficile. We compared sporulation levels in the UK epidemic C. difficile strain (P24), another clinical isolate (B31), and an environmental strain (E4) cultured in faecal emulsion containing subinhibitory concentrations of one of five hospital cleaning agents. The epidemic strain produced significantly more spores than the non-prevalent strains, and sporulation was further enhanced when this strain was cultured in faeces exposed to non-chlorine-based cleaning agents. The choice of cleaning agent can have a substantial effect on the persistence of C. difficile spores in the hospital environment.

Analysis of Variance↗
PubMed2000

A five year outbreak of methicillin-susceptible Staphylococcus aureus phage type 53,85 in a regional neonatal unit.

We identified a 5-year outbreak of a methicillin-susceptible Staphylococcus aureus (MSSA) strain, affecting 202 babies on a neonatal unit, by routine weekly phage typing all S. aureus isolates. Multiple staged control measures including strict emphasis on hand hygiene, environmental and staff surveillance sampling, and application of topical hexachlorophane powder failed to end the outbreak. S. aureus PT 53,85 (SA5385) was found on opened packs of Stomahesive, used as a neonatal skin protectant. Only following the implementation of aseptic handling of Stomahesive, and the use of topical mupirocin for staff nasal carriers of SA5385, and for babies colonized or infected with S. aureus, did the isolation rate of SA5385 decline. DNA fingerprinting indicated that > or =, 95% of SA5385 isolates were clonal. In vitro death rates of SA5385 on Stomahesive with human serum were significantly lower than on Stomahesive alone (P = 0.04), and on cotton sheet with serum (P = 0.04), highlighting the potential of this material as a survival niche. Phage typing remains a valuable, inexpensive and simple method for monitoring nosocomial MSSA infection.

Bacteriophage Typing↗
PubMed2000

Value of lysozyme agar incorporation and alkaline thioglycollate exposure for the environmental recovery of Clostridium difficile.

Clostridium difficile is an increasingly prevalent nosocomial pathogen. Environmental contamination by spores is believed to be a major factor propagating the spread of C. difficile. Various approaches including the use of bile salts have been described to enhance the recovery of C. difficile from clinical and environmental specimens. We found that lysozyme (5 mg/L) incorporated into a selective medium containing bile salts significantly increased the recovery of C. difficile from swabs of 197 environmental sites (11% versus 24% samples positive, P< 0.01). Furthermore, in a separate series of experiments additional use of cooked meat broth enrichment significantly enhanced the recovery of C. difficile (35% versus 45%, P = 0.009). Conversely, we found that pre-exposure to alkaline thioglycollate did not improve the yield of C. difficile. Lysozyme incorporation markedly increases the recovery of C. difficile from environmental samples probably by stimulation of spore germination. Our findings suggest that previous attempts to determine the level of environmental C. difficile contamination have markedly underestimated the true prevalence of this pathogen.

Agar↗
PubMed2000

In vitro activity of new generation fluoroquinolones against genotypically distinct and indistinguishable Clostridium difficile isolates.

We compared the activities of ciprofloxacin and levofloxacin with those of the newer fluoroquinolones grepafloxacin, moxifloxacin, sparfloxacin and trovafloxacin against Clostridium difficile isolates. As there is good evidence of marked clonal spread of C. difficile, we studied both genotypically distinct (n = 26) and indistinguishable (n = 28) isolates as determined by random amplified polymorphic DNA and ribosomal spacer PCR fingerprinting. The indistinguishable strains examined represent the main UK epidemic C. difficile clone. For 17 of 54 strains (31%) we were unable to read MICs following inocula preparation using Mueller-Hinton broth. Using Schaedler's broth for inocula preparation 93% of strains had readable MICs, although geometric mean MICs were uniformly higher (2.5- to 5.4-fold) compared with results using Mueller-Hinton broth. Moxifloxacin and trovafloxacin, followed by grepafloxacin, were the most active fluoroquinolones tested and were 3- to 4-fold more active than older agents such as ciprofloxacin by both MIC methods. Unexpectedly, clonal C. difficile strains had markedly reduced susceptibility compared with the distinct strains to each of the fluoroquinolones tested. Clonal strains were more than seven-fold or 12- to 29-fold less susceptible (according to geometric mean MICs) than distinct strains to both moxifloxacin and trovafloxacin, depending on the MIC method used. It remains to be seen whether the enhanced activity of new fluoroquinolones such as moxifloxacin in comparison with other fluoroquinolones against C. difficile implies that these agents are unlikely to be associated with C. difficile infection. However, clinical use of new generation fluoroquinolones in elderly hospitalized patients where C. difficile is endemic requires further study, particularly given the reduced antibiotic susceptibility to all fluoroquinolones of the readily transmissible UK C. difficile clone.

Anti-Infective Agents↗
PubMed2000

Combined cervical swab and urine specimens for PCR diagnosis of genital Chlamydia trachomatis infection.

OBJECTIVES: Sampling of both the cervix and urine increases the chance of detection of Chlamydia trachomatis compared with sampling either site alone. We determined the effect of combining urine and cervical swab specimens in the clinic setting on the sensitivity of C trachomatis polymerase chain reaction (PCR) testing. METHODS: For each of 100 women attending a genitourinary medicine clinic with high likelihood of genital C trachomatis infection, one endocervical swab was placed in transport medium and another in one of two aliquots of first void urine. Four PCR assays per patient (urine + swab, swab alone, and urine alone both pre- and post-freeze-thawing) were processed by automated C trachomatis PCR (Cobas, Amplicor). An inhibition control was included with each assay to identify specimens containing PCR inhibitors. RESULTS: 71% of women were Amplicor C trachomatis PCR positive (according to the results of at least one specimen). PCR test results were concordant for 95/100 patients, and of the five discordant result sets there was only one major discrepancy. Inhibitors of PCR were present in 22/400 specimens from 20 patients, and 16/22 were cervical swabs (p < 0.001). CONCLUSIONS: Combining a cervical swab with a urine specimen is acceptable for PCR testing for genital C trachomatis infection, and has the potential to increase further the cost effectiveness of DNA based screening for C trachomatis genital infection.

Chlamydia Infections↗
PubMed1999

Rapid diagnosis of central-venous-catheter-related bloodstream infection without catheter removal.

BACKGROUND: Current methods for the diagnosis of bloodstream infection related to central venous catheters (CVC) are slow and in many cases require catheter removal. Since most CVC that are removed on suspicion of causing infection prove not to be infected, removal of catheters unnecessarily exposes patients to the risks associated with reinsertion. METHODS: The gram stain and acridine-orange leucocyte cytospin test (AOLC) is rapid (30 min), inexpensive, and requires only 100 microL catheter blood (treated with edetic acid) and the use of light and ultraviolet microscopy. We assessed the gram stain and AOLC test in suspected cases of catheter-related bloodstream infection, in comparison with two methods requiring catheter removal (tip roll and tip flush), and a third technique, done in situ (endoluminal brush) in conjunction with quantitative peripheral-blood cultures. FINDINGS: 128 cases of suspected catheter-related bloodstream infection were assessed in 124 adult surgical patients (median duration of CVC placement was 16 days). In 112 (88%) cases CVC blood was obtainable. Catheter-related bloodstream infection was diagnosed in 50 cases (culture of the same organism from the catheter, in significant numbers, and from peripheral-blood culture). The sensitivity of the gram stain and AOLC test was 96% and the specificity was 92%, with a positive predictive value of 91% and a negative predictive value of 97%. By comparison, the tip-roll, tip-flush, and endoluminal-brush methods had sensitivities of 90%, 95%, and 92%, and specificities of 55%, 76%, and 98%, respectively. INTERPRETATION: The gram stain and AOLC test is a simple, and rapid method for the diagnosis of catheter-related bloodstream infection. This diagnostic method compares favourably with other diagnostic methods, particularly those that require the removal of the catheter, and can permit early targeted antimicrobial therapy.

Acridine Orange↗
PubMed1999

Antibiotics and Clostridium difficile.

Clostridium difficile is now established as a major nosocomial pathogen. C. difficile infection is seen almost exclusively as a complication of antibiotic therapy, and is particularly associated with clindamycin and third-generation cephalosporins. Depletion of the indigenous gut microflora by antibiotic therapy has long been established as a major factor in the disease. However, the direct influence of antimicrobials upon virulence mechanisms such as toxin production and adhesion in the bowel, and the exact mechanisms by which the organism causes disease remain to be elucidated.

Animals↗
PubMed1999

Subcutaneous fluid administration--better than the intravenous approach?

Hypodermoclysis is a method of subcutaneous fluid administration particularly useful in elderly patients and in palliative care settings where intravenous access may be difficult. Subcutaneous fluid delivery is an effective method of rehydration and of opioid administration, and can prevent the need for intravenous catheterization and consequently hospitalization. It is a simple procedure to initiate, safe, less distressing to the patient, and does not predispose to intravascular related infections. The reported incidence of infection at the delivery site is extremely low. However, local guidelines should be agreed so that a standardized protocol is operated and risks of localized infection are minimized.

Fluid Therapy↗
PubMed1999

Glove powder: implications for infection control.

Gloves are increasingly promoted for use by healthcare workers, but this use is not without risk. Data associating powdered gloves with an increased risk of latex allergy is available and there is circumstantial evidence that the powder used may increase bacterial environmental contamination. In animal models, corn starch, the material used as glove powder, promotes wound infection. Infection control teams need to be aware of this evidence and should support switching from use of powdered to powder free gloves.

Gloves, Protective↗
PubMed1999

Nosocomial diarrhoea.

Toroviruses have been reported as a new cause of nosocomial viral diarrhoea, and the role of astroviruses has been further elucidated. Polymerase chain reaction methods promise to improve the diagnosis and understanding of the aetiology and control of hospital-acquired viral gastroenteritis. A clearer picture of the impact and extent of Clostridium difficile diarrhoea has emerged, and several control measures have been described. An epidemic Clostridium difficile strain and toxin A-deficient strains have been reported. There is growing evidence that enterotoxin-producing Clostridium perfringens can also cause antibiotic-associated diarrhoea.

Journal Article↗