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Mark H Wilcox

Publications and source records attributed to Mark H Wilcox.

23 records · Page 2Linked to original sources
PubMed2003

Correlation between enterococcal biofilm formation in vitro and medical-device-related infection potential in vivo.

Hospital-acquired infections caused by enterococci have increased dramatically since the 1970s. Many nosocomial enterococcal bloodstream infections are associated with medical devices such as central venous catheters. The ability to form biofilm on medical devices is a potential virulence trait that may allow enterococci to cause infections in the expanding population of patients managed with such devices. In this study, the hypothesis that increased ability to form biofilm in vitro is associated with medical-device-related infection in vivo was tested. A microplate assay was employed to assess biofilm-forming characteristics of enterococci in 0.9 % (w/v) sodium chloride, an oligotrophic environment, and BHI, a nutrient-rich environment. Results were compared in isolates from different sources of infection. One hundred and nine enterococcal bloodstream isolates were assayed. Biofilm formation on microplates was demonstrated by all Enterococcus faecalis isolates and 16/38 (42 %) Enterococcus faecium isolates. E. faecalis isolates produced significantly more biofilm than E. faecium isolates in both media (P < 0.0001, Mann-Whitney U test). E. faecalis isolates from intravascular-catheter-related bloodstream infections (CRBSIs) produced significantly more biofilm than non-CRBSI isolates (P < 0.0001), or isolates of uncertain clinical significance (P < 0.0001). Biofilm formed by E. faecium isolates was not significantly affected by culture medium and did not differ between isolates from the different clinical categories. In conclusion, there was significantly more biofilm formed by E. faecalis isolates causing CRBSI compared with isolates from other types of infection or from isolates of uncertain clinical significance. The ability of E. faecalis isolates to form biofilm in vitro appears to be a marker of a virulence trait that enhances the ability of isolates to cause CRBSI.

Bacteremia↗
PubMed2002

Enterococcal intravascular catheter-related bloodstream infection: management and outcome of 61 consecutive cases.

Enterococci are an increasingly important cause of intravascular catheter-related bloodstream infection (CRBSI), but the evidence base for treating such cases is limited. Successful antimicrobial treatment of CRBSI while leaving the central venous catheter (CVC) in situ has been reported for some bacteria, such as coagulase-negative staphylococci, but the effectiveness of this approach for treating enterococcal CRBSI is unknown. We aimed to determine the effectiveness of treatment options for enterococcal CRBSI and whether CVC removal is mandatory. Treatment and outcome was determined in a 3 year cohort of patients with enterococcal CRBSI from a university teaching hospital. All episodes of enterococcal bacteraemia during the study (n = 268) were examined to identify the cohort of 61 CRBSIs. Outcomes were determined for various antimicrobial regimens with or without CVC removal. Forty-eight episodes were managed with CVC removal and 13 were managed with the CVC in situ. Forty of 48 (83%) and five of 13 (38%) episodes were cured with the CVC removed or left in situ, respectively. All five episodes cured with the CVC in situ were treated with a cell wall-acting antimicrobial plus an aminoglycoside. This antimicrobial combination was significantly more effective than either ampicillin or vancomycin monotherapy (P < 0.05), or antimicrobials to which isolates were not susceptible (P < 0.01) when the CVC remained in situ. We conclude that enterococcal CRBSI can be treated successfully without CVC removal. The combination of a cell wall-acting antimicrobial with an aminoglycoside was the most effective regimen when the CVC remained in situ in this small group of patients. Although CVC removal was associated with a high cure rate, it did not guarantee treatment success.

Adolescent↗
PubMed2002

Clostridium difficile.

Clostridium difficile is the most commonly identified infective cause of antibiotic associated diarrhoea. Broad spectrum antibiotics, are most frequently incriminated, although short (<3 day) antibiotic courses cause fewer episodes. Gold standard cell-culture based cytotoxin assays have been compared to rapid immunoassays, which are less effective, especially since toxin A negative, toxin B positive strains have been shown to be truly virulent. Details of colonization and adherence mechanisms have been revealed, and clonal spread has been demonstrated. The mainstay of treatment of C. difficile infection remains metronidazole. Justified fears over resistance are leading to development of alternative therapeutic strategies. These include a toxin binding polymer and ongoing biotherapy research. An antibody rise to toxin A during an episode of C. difficile diarrhoea protects against recurrence, and trials are in progress to investigate immunization: a toxoid vaccine which is immunogenic and safe in healthy volunteers shows promise for the future.

Bacterial Toxins↗
PubMedDate not supplied

The use of a rapid in situ test in the detection of central venous catheter-related bloodstream infection: a prospective study.

BACKGROUND: Acridine orange leukocyte cytospin (AOLC) is a highly sensitive and specific test for the detection of catheter-related bloodstream infection (CRBSI). We evaluated the role of the AOLC test in early detection or exclusion of CRBSI and compared the cost of managing patients with suspected CRBSI. METHODS: On the day of clinical suspicion of CRBSI, blood samples were obtained from the catheters for the AOLC test, and peripheral blood samples were obtained for quantitative blood cultures. Catheters with positive AOLC results were immediately removed for culture and replaced if necessary. Catheters with negative AOLC tests were left in situ. We compared the catheter lifespan in patients with suspected CRBSI who had positive and negative AOLC tests and calculated the cost of using the AOLC test to prevent indiscriminate catheter removal. RESULTS: Fifty patients with suspected CRBSI were tested and prospectively followed up. Catheters were removed in 10 patients (20%) with a positive AOLC test, and CRBSI was confirmed in each case subsequently. Selective removal of catheters based on AOLC tests significantly extended the lifespan of catheters compared with an indiscriminate removal of catheters based on clinical suspicion of CRBSI (median, 24 versus 11 days; p < .0001). The cost of an AOLC test and selective catheter replacement strategy was significantly lower than the cost of routine removal and replacement of catheters (median, pounds sterling 9.53 versus pounds sterling 64.20; p < .0001). CONCLUSION: The AOLC test enables a rapid detection of CRBSI, avoids unnecessary removal of catheters, and provides a cost-efficient management approach in patients with suspected CRBSI.

Acridine Orange↗