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Biomedical subjects

G M Scott

Publications and source records attributed to G M Scott.

At least 37 records · Page 2Linked to original sources
PubMed1999

Preliminary analysis of the transmission dynamics of nosocomial infections: stochastic and management effects.

A simple mathematical model is developed for the spread of hand-borne nosocomial pathogens such as Staphylococcus aureus within a general medical-surgical ward. In contrast to previous models a stochastic approach is used. Computer simulations are used to explore the properties of the model, and the results are presented in terms of the pathogen's successful introduction rate, ward-level prevalence, and colonized patient-days, emphasizing the general effects of changes in management of patients and carers. Small changes in the transmissibility of the organism resulted in large changes in all three measures. Even small increases in the frequency of effective handwashes were enough to bring endemic organisms under control. Reducing the number of colonized patients admitted to the ward was also an effective control measure across a wide range of different situations. Increasing surveillance activities had little effect on the successful introduction rate but gave an almost linear reduction in colonized patient-days and ward-level prevalence. Shorter lengths of patient stay were accompanied by higher successful introduction rates, but had little effect on the other measures unless the mean time before detection of a colonized individual was large compared to the mean length of stay. We conclude that chance effects are likely to be amongst the most important factors in determining the course of an outbreak. Mathematical models can provide valuable insights into the non-linear interactions between a small number of processes, but for the very small populations found in hospital wards, a stochastic approach is essential.

Computer Simulation↗
PubMed1999

Infection control--evidence into practice.

This paper arises out of two workshop sessions held at the fourth meeting of the Federation of Infection Societies, Manchester, 1997. The aims of the workshops were, first, to identify the factors which impede the process of translating research findings into infection control practice and second, to suggest how these barriers may be overcome. Key points from the workshops are presented within an idealized framework of creating, implementing and maintaining evidence-based infection control practice. This lends structure to our exploration of the evidence underlying infection control guidance and the reasons why such guidance often does not result in appropriate action by healthcare workers. The strengths and weaknesses of each stage of the process are examined, using examples provided by participants at the workshop.

Attitude of Health Personnel↗
PubMed1999

The control of hyperendemic glycopeptide-resistant Enterococcus spp. on a haematology unit by changing antibiotic usage.

The rectal carriage of glycopeptide-resistant Enterococcus spp. (GRE) had been established at approximately 50% in a series of prevalence studies on a busy haematological malignancy unit. The aim of this study was to reduce the chance of patients acquiring GRE. A prospective three-phase sequential study was performed. In Phase 1, the acquisition rate of GRE detectable by rectal swab was measured without any intervention for a period of 4 months. For the following 8 months (Phase 2), the first-line treatment for febrile neutropenic episodes was changed from monotherapy with ceftazidime to piperacillin/tazobactam. In addition, an intense education programme was introduced to improve hygiene to reduce the risk of case-to-case spread. In the final 4 months (Phase 3), ceftazidime was again used as the first-line antimicrobial, while continuing the same level of training in relation to hygiene. The carriage of GRE was measured from rectal swabs done weekly. During the initial 4 months, at any time, 40-50% of patients in the unit were colonized with GRE, and 43 of 75 (57%) new patients initially negative for GRE acquired it within 6 weeks of their admission. In Phase 2, 25 patients out of 129 (19%) acquired GRE, with the acquisition rate falling progressively so that in the last 3 months, only one new patient acquired GRE (logrank comparison of probabilities for cohort 1 vs cohort 2b: P < 0.0001). A return to ceftazidime in Phase 3 was associated with a return of the risk of acquiring detectable GRE colonization, despite continued hygiene teaching and surveillance, with 21 out of 58 patients (36%) acquiring GRE (cohort 1 vs cohort 3: P = 0.08). Glycopeptide usage was not reduced during the period of the study. Clinical cases were seen only in Phases 1 and 3. Although the reduction in the risk of acquiring GRE may have been due in part to hygiene practices as well as to the change in antimicrobial usage, or may have occurred spontaneously for other reasons, the return of the problem with the reintroduction of ceftazidime strongly suggests that this antibiotic was responsible for encouraging the acquisition of detectable GRE.

Adolescent↗
PubMed1998

Comparison of wound scoring methods for use in audit.

Accurate information on the prevalence of surgical wound infection is difficult to obtain; outpatient follow-up is often inadequate. For two months in 1993 and again in 1995, surgical wounds throughout one hospital were examined by the same observer with the intention of comparing different methods for assessing wound infection. Two standard definitions [Centers for Disease Control (CDC), USA and National Prevalence Survey (NPS), UK] were compared with ASEPSIS and the Southampton method. In 1993, 325 wounds in 230 patients were examined with follow-up of 203 (88%) patients. In 1995, 559 wounds were surveyed in 375 patients with follow-up in 364 (97%). Patient groups in the two years were similar. ASEPSIS identified 92 (13%) wounds as having scored over 20 points indicating infection, and another 16.5% having disturbance of healing. There was no significant difference between the two surveys. The two scoring methods were more sensitive than the standard definitions but CDC and NPS did not differ significantly from each other. Between 44 and 47% of clean wounds identified as infected by standard definitions were classed as disturbance of healing by ASEPSIS. All methods were labour-intensive and to implement any one of them on a regular basis would require a full-time investigator. The first surveillance program with feedback of results to the surgeons did not significantly affect the rates two years later.

Hospitals↗
PubMed1997

The murine cytomegalovirus (MCMV) homolog of the HCMV phosphotransferase (UL97(pk)) gene.

The murine cytomegalovirus (MCMV) M97 gene is homologous with both eukaryotic protein kinases and the phosphotransferases of herpesviruses. The gene conserves the domain structure of protein kinases and of the human cytomegalovirus UL97 (phosphotransferase) gene. An M97 transcript of 2.5 kb is present predominantly at late times, and much smaller quantities of the transcript are detected at early times postinfection. Comparison of the DNA sequences of the complete M97 genes from 12 ganciclovir-sensitive and aciclovir-sensitive strains of MCMV showed that the sensitive isolates strongly conserve the sequence of the catalytic domains, but have only moderate conservation of the sequence of the amino-terminal (regulatory) region. MCMV provides a useful model for studying the in vivo function of the phosphotransferase genes of the betatherpesviruses and has potential for use in studies of antiviral resistance.

Amino Acid Sequence↗
PubMed1996

Bacterial contamination of autologous bone marrow during processing.

As part of an audit of the processing of autologous bone marrow, we found that marrow was often contaminated with organisms potentially pathogenic to neutropenic recipients. One of 14 marrows studied was found to be contaminated before the processing stage and five others became contaminated during processing. The organisms isolated at these stages were Propionibacterium sp., coagulase-negative staphylococci, Staphylococcus aureus and coryneforms, suggesting that the skin was the likely source of contamination. Five out of the 11 marrows returned to patients were found to be contaminated after thawing. Two of these were marrows previously shown to be contaminated with coagulase-negative staphylococci before freezing, and from these coagulase-negative staphylococci were isolated again, in one case the strains were indistinguishable. New organisms isolated after thawing included Bacillus sp. and Corynebacterium sporogenes suggesting contamination from the environment. No infections attributable to these organisms were demonstrated in any of the patients studied.

Bacterial Infections↗
PubMed1996

Oral Mycobacterium avium complex infection in a patient with HIV-related disease. A case report.

Mycobacterium avium complex infection is a common complication of the later stages of AIDS. Although a recognized cause of oral lesions, atypical mycobacteria are rarely detected in AIDS-related oral ulceration. Here we report a case of oral ulceration in a patient in the later stages of AIDS in which atypical mycobacteria were detected both histologically and microbiologically. The features of this case are similar to the one other case previously reported permitting some characterization and comparison of the clinical features of mycobacterium avium complex infection in AIDS.

AIDS-Related Opportunistic Infections↗
PubMed1995

Restriction fragment length polymorphism analysis rules out cross-infection among renal patients with tuberculosis.

A cluster of five cases of tuberculosis occurred on a renal unit in 1993. The initial impression was that this was an outbreak, and cross-infection was suspected. Restriction fragment length polymorphism analysis was carried out on the strains of Mycobacterium tuberculosis isolated from these cases, using a DNA probe directed against the insertion sequence IS6110. DNA fingerprints obtained by this method differed for all the strains tested, ruling out cross-infection as a cause of the outbreak. This technique is a useful adjunct to standard epidemiological investigations in outbreaks of tuberculosis.

Adult↗
PubMed1994

A nosocomial outbreak due to non-encapsulated Haemophilus influenzae: analysis of plasmids coding for antibiotic resistance.

An outbreak of infections with non-encapsulated Haemophilus influenzae, resistant to ampicillin, chloramphenicol, sulphonamide and tetracycline involved 13 elderly patients and three nurses on acute admission and care of the elderly wards. Thirty-two isolates were found to be indistinguishable on analysis of biotype, antibiogram, serotype and major outer membrane proteins (MOMP). Plasmids could not be identified in the original isolates but after mating with a Rec A H. influenzae recipient, the resultant transconjugates were found to harbour either a 72 kilobase pair (kB) plasmid coding for resistance to chloramphenicol, ampicillin, sulphonamide and tetracycline or a 65 kB plasmid coding for resistance to chloramphenicol, ampicillin and sulphonamide. Both plasmids yielded virtually indistinguishable restriction digest patterns. This suggests that the tetracycline resistance gene (Tc gene) is a non-essential component of one basic plasmid responsible for the multiple antibiotic resistances seen in the strains recovered during the outbreak. This illustrates the value of plasmid profiles to compare strains of non-encapsulated H. influenzae, and suggests that plasmid restriction enzyme analysis is critical.

Aged↗
PubMed1994

Audit of infection in continuous ambulatory peritoneal dialysis.

The major cause of failure of continuous ambulatory peritoneal dialysis is peritoneal or exit site infection with Staphylococcus aureus. From 1989-1992, eradication of nasal and perineal carriage, continued use of an occlusive dressing to the exit site, improved aseptic technique for dressing changes by the patient and avoidance of wetting of the dressing were used in an attempt to reduce staphylococcal infections. By comparison with the 3-year period prior to intervention, a significant increase in the life of the catheters was achieved (removed at 1 year, 13 vs. 28%, P < 0.001) with a reduction in episodes of peritonitis due to S. aureus. The study was not prospectively controlled but there did not appear to be any other factor to account for the sudden and consistent improvement observed.

Catheterization↗
PubMed1994

Reducing the loss of implants following penile prosthetic surgery.

OBJECTIVE: To assess the factors associated with loss of implant following penile prosthetic surgery and to make alterations in the management of patients to prevent this from occurring. PATIENTS AND METHODS: A retrospective analysis was carried out of the factors associated with post-operative infection and erosion in 188 patients who underwent implantation of penile prostheses. A prospective study was then established in which 62 patients were managed by a set protocol designed to counteract the factors identified as being contributory to loss of implants in the retrospective review. RESULTS: In the retrospective study nine (4.8%) patients lost a prosthesis due to erosion. Erosion was noted to be more common with one type of implant which has since been modified. Infection was the cause of prosthesis loss in 12.2% of patients in the retrospective review. The new protocol resulted in a significantly reduced infection rate in penile prostheses to 1.6% (P < 0.05). CONCLUSION: With attention to simple antiseptic prophylaxis, antibiotic penetration and continuing audit, a significant improvement in the loss of penile prostheses can be achieved along with a reduction in the amount of antibiotics prescribed.

Adult↗