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Biomedical subjects

R R Marples

Publications and source records attributed to R R Marples.

At least 55 records · Page 3Linked to original sources
PubMed1986

Colonization by gentamicin-resistant Staphylococcus epidermidis in a special care baby unit.

Babies entering a special care baby unit during a 3-month period were studied prospectively for colonization by gentamicin-sensitive and -resistant coagulase-negative staphylococci (CNS). Gentamicin-resistant isolates were characterized by biotyping, antibiotic sensitivity pattern and phage-typing. All the babies studied became colonized with gentamicin-resistant CNS and often with multiple strains. Gentamicin-sensitive CNS usually appeared first and predominated, but gentamicin-resistant staphylococci could be detected by enrichment culture at a median time of 1 day, and, by direct culture at a median time of 4 days. Similar strains were found in the environment and nasal carriage was detected in 60% of the staff of the unit by enrichment culture. The gentamicin-resistant strains were all resistant to benzylpenicillin and other antibiotics. No particular pathogenic strain could be identified, but clusters of colonizations by distinguishable strains were noted. Biotype SVI was frequently encountered, particularly among clinically significant isolates.

Anti-Bacterial Agents↗
PubMed1986

Problems in the investigation of an apparent outbreak of coagulase-negative staphylococcal septicaemia following cardiac surgery.

Two hundred and twenty-six hospital staff and patients were investigated for the carriage of gentamicin-resistant coagulase-negative staphylococci (CNS) during an apparent outbreak of infection after cardiac surgery. Of the four index strains from infected wounds, three were indistinguishable. The carriage of similar organisms was widespread, particularly among ITU staff (72%) and patients. Ninety-one of the 296 gentamicin-resistant isolates were further investigated, and of these 33 were indistinguishable from index strains even with the use of specialized techniques. Our experience indicates that in outbreaks of infection caused by gentamicin-resistant CNS, resources should be focused on the interruption of transmission and prevention of introduction of these organisms to susceptible patients.

Carrier State↗
PubMed1986

Bacteriological characters of strains of Staphylococcus aureus submitted to a reference laboratory related to methicillin resistance.

Methicillin-resistant Staphylococcus aureus (MRSA) strains present an increasing clinical problem. Analysis of 2679 strains submitted to a reference laboratory in the first quarter of 1983 and 3050 strains submitted in summer 1984 showed 479 and 593 multi-resistant strains. The proportion of methicillin-resistant strains classified as epidemic rose from 5.9 to 10.2%. Other methicillin-resistant strains continued to occur but other methicillin-sensitive multi-resistant strains appeared to fall. A strain with defined characters could be recognized in the Thames regions.

Bacitracin↗
PubMed1986

Coagulase production by strains of Staphylococcus aureus of differing resistance characters: a comparison of two traditional methods with a latex agglutination system detecting both clumping factor and protein A.

Five groups of strains of Staphylococcus aureus (54 in total) were tested by slide and tube coagulase methods with rabbit and human plasma, and the results were compared with a latex test for both clumping factor and Protein A (Staphaurex, Wellcome Foundation). The five groups comprised: epidemic methicillin resistant S aureus (group 1); other methicillin resistant S aureus (group 2); other resistant S aureus (group 3); other S aureus (group 4); and a group of reference strains, not all true S aureus (group 5). Groups 1, 3, and 4 gave consistently strong positive results with the tube test and the latex test and less strong positive results with the slide test. Group 2 strains sometimes gave weak or negative results in slide and latex tests, but tube tests with both types of plasma were strongly positive. Only within group 5 strains were negative results in the tube test found. Group 1 strains showed no diminution in expression of free coagulase or of clumping factor. The latex test was more sensitive than the slide test but less sensitive than the tube test. Doubtful or negative slide test or latex test results, particularly with strains resistant to methicillin, should be checked by a tube coagulase test.

Animals↗
PubMed1985

Adhesive tapes in the special care baby unit.

Semi-quantitative sampling of 37 taped sites and 37 matching control sites in 30 babies in a special care baby unit showed a tendency for bacterial growth under the cardiac monitors or the occlusive plastic adhesive tape to be greater than at the control site. This tendency was demonstrable even when potential pathogens were considered. During the study, an outbreak due to Candida albicans occurred. Antibiotic resistance of coagulase-negative staphylococci was marked and this, and other evidence, suggested that part of the skin flora was acquired from the unit.

Adhesives↗
PubMed1984

Characters of coagulase-negative staphylococci and micrococci from cases of endocarditis.

Strains of coagulase-negative staphylococci and micrococci submitted to a reference laboratory from 137 cases of endocarditis over a 5 year period were reviewed. Staphylococcus epidermidis biotype 1 (SII) was the commonest biotype in all groups of patients but exceeded 80 per cent in the 61 patients who had undergone prosthetic valve surgery and the 16 patients who had undergone other forms of surgery. Biotype 4 (SVI) was recovered from 10 of the 34 patients without surgery. Strains from prosthetic valve endocarditis were frequently resistant to many antibiotics while strains from natural valve endocarditis were frequently sensitive to all, or resistant only to penicillin. The value of bacteriophage typing was confirmed.

Adult↗
PubMed1984

Microbiological aspects of the 1980 national prevalence survey of infections in hospitals.

The records of the 1980 national prevalence survey of infection in hospitals were re-assessed from a microbiological point of view. Of 407 records of Escherichia coli, 71 per cent came from the urinary tract while the commonest source of Staphylococcus aureus was from skin infections. These yielded only 41 per cent of the 303 records. Proteus spp. were recorded 166 times, Pseudomonas spp. 115 times and Klebsiella spp. 101 times. These came mainly from the urinary tract but other sources were important. Streptococcus pneumoniae, Haemophilus influenzae, Mycobacterium tuberculosis and the viruses were associated with community infections while E. coli, Proteus spp., Pseudomonas spp., Klebsiella spp., Str. faecalis and non-aureus staphylococci were associated with hospital-acquired infections. The prevalence of bacteraemia was re-assessed.

Adolescent↗
PubMed1983

Contaminated first-aid dressings: report of a working party of the PHLS.

In a collaborative study 12 Public Health Laboratory Service laboratories and the Division of Hospital Infection, Central Public Health Laboratory, investigated the degree of contamination of standard dressings produced by manufacturers in India or in England by a comparison of the results of culture of 25 sterilized dressings with those of 25 untreated dressings. Of the 38 batches of dressings made in India 27 (71%) were judged contaminant and another six could be so judged when Bacillus species were examined. In two batches laboratory contamination precluded a judgement and only three batches passed the test. Of the 27 batches made in England, only three gave any evidence of contamination at the lowest level of significance. Repeat investigation of one of these batches gave no evidence of contamination. Organisms of the genus Bacillus and fungi were associated with contamination; micrococci and propionibacteria were laboratory contaminants. There was evidence for both failure and sterilization and of contamination after sterilization during the manufacture of dressings.

Aspergillus niger↗
PubMed1982

Sex, constancy, and skin bacteria.

Quantitative studies of the aerobic flora of seven skin sites in 16 volunteers were repeated after 3 months. The total aerobic densities of the sites differed, male carried more organisms than females and also more biotypes. Qualitative differences in the flora could be detected.

Bacteria↗
PubMed1982

Changing resistance to antimicrobial drugs, and resistance typing in clinically significant strains of Staphylococcus epidermidis.

Resistance to 11 antimicrobial drugs was assessed in 532 clinically significant strains of Staphylococcus epidermidis received in the years 1978, 1979 and 1980 and compared with that of strains collected in 1976 and 1977 for an international study. Only 14% of strains were sensitive to all the drugs tested. Resistance to gentamicin increased significantly from 7% to 33% during the study period. The degree of association between pairs of drugs was assessed. There was strong association between resistance to methicillin, aminoglycosides and macrolide antibiotics and only weak association between resistance to novobiocin, tetracycline, chloramphenicol and penicillin. Patterns of resistance were complex and may be useful as an accessory typing system.

Aminoglycosides↗
PubMed1982

Evaluation of a micromethod gallery (API Staph) for the identification of staphylococci and micrococci.

A collection of 300 well-characterised strains of staphylococci and micrococci was examined by a commercially available gallery micromethod (API Staph). The results were compared with biotyping by conventional methods. The gallery micromethod broadly agreed with the biotyping scheme used but gave an identification from the index supplied in less than 30% of the trials. Reproducibility was better after 48 h incubation than after 24 h but was poor for the tests for phosphatase and acetoin. When compared with the results of conventional tests, the tests for acetoin, phosphatase and urea were unsatisfactory.

Bacteriological Techniques↗
PubMed1980

Micrococcus in the blood.

Eight isolates of micrococci from the bloodstream of six patients obtained under circumstances suggesting a pathogenic role were studied in detail. The organisms were remarkably uniform in cultural, biochemical and antibiotic-susceptibility characters. All strains showed high resistance to methicillin and hydrolysed arginine. The characters found did not correspond with those of any hitherto described species, but were closest to Micrococcus lylae.

Anti-Bacterial Agents↗
PubMed1979

A laboratory model for the investigation of contact transfer of micro-organisms.

The model was based on grasping a fabric-covered bottle contaminated with a strain of Staphylococcus saprophyticus, then grasping a sterile fabric-covered bottle and counting the organisms transferred. When the donor fabric was moist 10% of the available cells passed onto the hands, but this fell to 0.05% when the inoculum dried. Transfer from wet hands to the fabric amounted to 85%, but in the complete model only 0.06% of the available cells were transferred. The model was used to assess simple methods of degerming the hands. Washing the hands reduced transfer by 95%, while washing in 70% alcohol reduced transfer by 99.99%. Lesser procedures investigated included applying 0.2 ml of 80% ethanol to the hands, which reduced transfer by 93%.

Cross Infection↗