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Biomedical subjects

C A Mackintosh

Publications and source records attributed to C A Mackintosh.

14 recordsLinked to original sources
PubMed1992

An 11-month incidence study of infections in wards of a district general hospital.

Between March 1988 and January 1989, an incidence study of infections in patients occupying 122 beds in a district general hospital was undertaken. Nursing notes, medical notes, temperature charts, drug prescription charts and laboratory information were reviewed three times a week to determine if patients had infection which met strict case definitions. In addition, the surveyor consulted with ward nursing and medical staff for clarification of symptoms and signs indicative of infection. During the study, 668 infections were identified amongst 3326 patients. Three hundred and thirty-eight (51%) were community-acquired infections (CAI) and 330 hospital-acquired infections (HAI). Excluding 24 HAI acquired in other hospitals, the incidence rates were 9.2 HAI per 100 discharges, and 1.1 HAI per 100 patient days. The common types of CAI were pneumonia, abdominal infection and urinary tract infection. The main types of HAI were urinary tract infection, surgical wound infection and pneumonia. The microorganisms most frequently associated with CAI and HAI were Gram-negative bacilli.

Adolescent↗
PubMed1991

Surveillance of methicillin-resistant Staphylococcus aureus in England and Wales, 1986-1990.

The incidence of methicillin-resistant Staphylococcus aureus in England and Wales was monitored by a weekly reporting scheme from early 1986 to March 1990. Potential coverage was approximately two-thirds of hospital beds. Reporting centres fell from a peak of 210 in 1986 to a low of 101 centres early in 1989 with later recovery. There were 2367 positive reports in 1986, 2174 in 1987, 1700 in 1988, 1701 in 1989 and 632 in the first quarter of 1990. Colonizations outnumbered infections by 2:1. There were marked regional differences: North-East Thames was dominant in 1986 and 1987, and then declined; South-East Thames showed a dramatic increase in 1988 which continued. Other regions showed less significant changes but there were continuing problems in the South-Western Region and in the West Midlands. Some of these changes were related to the decline of EMRSA-1, possibly due to the introduction of effective control measures, and to the emergence of EMRSA-3 in South-East Thames and its spread to Wessex.

Bacteriophage Typing↗
PubMed1990

A survey of methicillin-resistant Staphylococcus aureus affecting patients in England and Wales.

For a six-month period between October 1987 and March 1988, 660 isolates of methicillin-resistant Staphylococcus aureus (MRSA) from 570 patients were sent to the Staphylococcus Reference Laboratory at Colindale to supplement the National reporting survey of MRSA in England and Wales. The isolates were characterized by phage typing, antibiotic susceptibility and by selected biochemical tests. Patient details were also surveyed. Fourteen strains affected more than one hospital and were called multi-hospital epidemic strains. One strain, EMRSA-1, accounted for more than 40% of isolates and of patients. Other epidemic strains were defined. Ten additional strains were restricted to single hospitals. Only 25 primary isolates were non-typable but 67 sporadic typable strains occurred. The patients affected were approximately equally either infected or colonized. The sexes were represented equally. Orthopaedic and geriatric wards were over-represented. Epidemic strains were clumping factor positive while some sporadic strains were weak producers. Urea alkalinization and protein A production could supplement phage typing and antibiotic resistance in strain recognition.

Adult↗
PubMed1986

The dispersal of bacteria and skin scales from the body after showering and after application of a skin lotion.

Application of a skin lotion to the body after showering greatly reduced the number of bacteria and skin scales dispersed from 10 men and 10 women. This effect lasted for at least 4 h when surgical clothing was worn. The use of a skin lotion to reduce bacterial dispersal could provide a simple and inexpensive alternative to an ultraclean air system or uncomfortable operating clothing during surgery requiring these procedures.

Humans↗
PubMed1985

Evaluation of three serological tests for detection of antibody to Pseudomonas aeruginosa in human sera.

Four hundred and ninety-five sera from 325 patients from whom Pseudomonas aeruginosa had been isolated and 86 control sera were tested for antibody by indirect haemagglutination tests (HAT) and complement fixation tests (CFT) using a polyvalent pseudomonas serotype-specific vaccine antigen, PEV-02. Sera were also tested by countercurrent immunoelectrophoresis (CIE) for precipitins to a species-specific protein antigen. Control sera gave titres of 160 or less by HAT and 20 or less by CFT. 2-Mercaptoethanol resistant antibody titres (immunoglobulin G) were below 40 for all control sera and none of the latter contained precipitins to common antigen. Of 325 patients, 156 (48%) gave titres of 320 or greater by HAT and of these, 114 (73%) showed elevated immunoglobulin G titres. Less patients with positive blood cultures than expected were positive by HAT and more patients with bone infections gave raised immunoglobulin G titres than expected. Cystic fibrosis patients were invariably seropositive by all tests. There was a correlation between positive CIE and CFT tests, especially in patients who were positive by HAT. Approximately half of 83 patients tested gave a serotype-specific antibody response. The tests were of little value in confirming clinically evident acute infections, but in cases of doubtful infection they did provide confirmatory evidence of an antibody response in approximately one-third of patients culture-positive for Pseudomonas aeruginosa.

Antibodies, Bacterial↗
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↗
PubMed1984

An extended model for transfer of micro-organisms via the hands: differences between organisms and the effect of alcohol disinfection.

A model for contact transfer of micro-organisms by hand has been extended to include representatives of bacterial species responsible for a majority of hospital-acquired infections. The ability of the organisms to transfer from contaminated fabrics to hands and from hands to sterile fabrics was measured, as was their ability to survive on the skin of the hands. There were differences between the species. Staphylococcus saprophyticus transferred well to the hand but not as well from hand to fabric as the other species; it survived well on skin. Pseudomonas aeruginosa, Klebsiella aerogenes and Serratia marcescens transferred moderately well overall and also survived on the skin. These results were in contrast to those obtained with a strain of Escherichia coli and one of Streptococcus pyogenes. The contact transfer model was used to investigate the use of small volumes of alcohol in preventing transfer via the hands. An alcohol handrub of either 0.3 ml 80% ethanol or 0.3 ml 70% isopropanol gave reductions in transfer slightly less than that of a soap and water wash. Raising the volume, and consequently the contact time, to 0.5 ml 70% isopropanol gave a 14000-fold reduction in transfer, statistically indistinguishable from that of a thorough soap and water wash (9800-fold reduction).

1-Propanol↗
PubMed1978

The evaluation of fabrics in relation to their use as protective garments in nursing and surgery. I. Physical measurements and bench tests.

Eleven fabrics selected to provide a representative range of yarns and weaves have been examined microscopically and subjected to a series of tests. The observations were directed towards assessing the potential ability of each fabric to resist penetration by particles, such as skin scales, which might carry micro-organisms. The number, size and shape of pores penetrating through the material were estimated and the penetration of test dusts assessed in several ways. While, generally, the relative merits of the fabrics are similar whatever test or measurement is considered there are a number of significant exceptions which reflect peculiarities of the test system or of a fabric. Comparison with the results of dispersal experiments with volunteers wearing garments made of the fabrics is made in a following paper.

Gossypium↗
PubMed1978

The evaluation of fabrics in relation to their use as protective garments in nursing and surgery. II. Dispersal of skin organisms in a test chamber.

The effectiveness of a representative range of fabrics in restricting dispersal through them of dry skin-borne bacteria has been examined. The fabrics were tested made up into trousers which were worn by volunteers during standardized exercise in a test chamber operated within a unidirectional flow clean-air room. Under these conditions, with careful attention to sealing at ankles and waist, it was possible to estimate penetration as low as 0.3%. Penetrations as low as 1% were observed with some synthetic fabrics. These had a relatively high surface resistivity and developed significant electrostatic charges. When the observed values for penetration were compared with the results of a series of measurements and tests made on the fabrics it was clear that the correlation between these values and the other results was in every case very close for all the five woven cotton or cotton terylene fabrics but that no measurement or test was capable or predicting the behaviour of all the other materials in dispersal experiments. The inherent variability of dispersal experiments seems to be very great. With a standard deviation of the approximately log-normal distribution of the experimental values as high as about 2 times the mean, it is necessary to carry out as many as 20 replicate experiments in order to differentiate with certainty between garments with a two-fold difference in penetration.

Gossypium↗
PubMed1978

The dimensions of skin fragments dispersed into the air during activity.

There was a 1000-fold difference between the highest and the lowest mean rate of dispersal of bacteria-carrying particles during exercise among a group of three male and three female subjects. Differences in the numbers of skin fragments dispersed and in the proportion of these carrying bacteria were almost equally responsible for this. Since there is little difference between individuals in the rate of skin replacement the differences in the rates of dispersal of skin fragments during exercise must reflect large variations in the amount of skin surface removed in other ways. The skin fragments dispersed had a wide size range extending below 5 micrometer for the minimum projected diameter (MPD). The median MPD was about 20 micrometer with 7-10% less than 10 micrometer. Many of the particles could therefore pass freely through tightly woven fabrics with pores up to 10-15 micrometer which might seem to be impenetrable to whole corneocytes, typically larger than 30 X 40 micrometer in the hydrated state.

Air Microbiology↗