Biomedical subjects
B J Collins
Publications and source records attributed to B J Collins.
Surveys of hospital infection in the Birmingham region. I. Effect of age, sex, length of stay and antibiotic use on nasal carriage of tetracycline-resistant Staphyloccus aureus and on post-operative wound infection.
Cross-sectional surveys of infection in relation to ward structure and practice were made in 38 hospitals between 1967 and 1973, including repeat surveys in 12 hospitals. The survey team (a research nurse and a senior microbiologist or technician) visited one ward a day and entered data on patients, including appearance of wounds seen at change of dressings, on the structure of the ward, and on ward practices; bacteriological swabs were taken from noses of all patients and staff of wards visited and from infected or open wounds, also from some environmental sites. Effect of age, sex, length of hospital stay and antibiotic use on carriage of tetracycline-resistant Staphylococcus aureus and on post-operative sepsis are considered here.Clinical infection (sepsis), further classified as ;severe', ;moderate' or ;mild' in accordance with a code of physical signs, including inflammation and suppuration, was found in 6.1% of clean undrained operation wounds. Drained wounds and those through hollow, heavily colonized viscera (;contaminated' wounds) had higher sepsis rates than undrained and ;clean' wounds; there was less sepsis with closed drainage and with small drains. Staph. aureus (24%) was the commonest single bacterial species, but gram-negative bacilli (50%) were found in a much larger proportion of septic wounds. The results showed that the infection rate was lowest among patients between 20 and 40 years old. Infection was significantly more common in male than in female patients.Nasal carriage of tetracycline-resistant Staph. aureus, used as an index of hospital-acquired infection, was commonest in geriatric patients and least common in gynaecological patients. There was correlation between nasal carriage of tetracycline-resistant staphylococci and age of the patient, length of hospital stay, sex, (male greater than female), operative treatment, and treatment with tetracycline, ampicillin and nitrofurantoin, but not with penicillin.
Disinfection of baths and bathwater.
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Letter: Hygiene of babies' incubators.
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Peripheral control of drinking: gastrointestinal filling as a negative feedback signal, a theoretical and experimental analysis.
The studies described here investigated the hypothesis that the osmotic postingestional satiety signal proposed by McCleary operates through a mechanism related to gut filling rather than by osmotically induced shifts of fluid from osmoreceptors in the brain. A control theory model is presented, which was designed to make quantitatively explicit the hypothesis under question. The results showed that when mannitol, which is not absorbed from the intestine, is added to a highly palatable saccharin-glucose mixture, the amount of fluid consumed decreased in inverse proportion to the mannitol concentration. Mannitol was also shown to block fluid absorption from the intestine at a low concentration (approximately .070 M) and at higher concentrations to lead to a net flux of fluid into the intestinal lumen. It was also shown that mannitol in concentrations that reduced the intake of the palatable solution did not induce thirst when the animals were in water balance. It did induce thirst, however, when the animals were tested in a state of negative water balance. The results of these studies, considered as a whole, support the view that McCleary's osmotic postingestional satiety signal acts as an intestinal distention signal rather than by inducing thirst. The model is found to be reasonably accurate as a first approximation, and suggestions are made for improvements.
Pseudomonas aeruginosa in hospital sinks.
Pseudomonas aeruginosa was isolated from sink waste-traps in 27 of 116 (23.3%) samples from a large general hospital and from 19 of 47 (40.4%) samples from a burns unit at another hospital. Smaller proportions of samples from sink outlets and surfaces of basins yielded Ps. aeruginosa. A waste-trap heater ('Econa') used twice daily for fifteen minutes reduced the isolations of Ps. oeruginosa from waste-traps to a very low level; isolations of other organisms were also reduced, though to a smaller extent. Despite the continuing high frequency of Ps. aeruginosa in sinks and some other moist hospital sites, Ps. aeruginosa infections were infrequent in the general hospital and had been greatly reduced by the successful use of various prophylactic measures in the burns unit.
Tests of disinfection by heat in a bedpan washing machine.
Tests of effectiveness of disinfection of metal and polypropylene bedpans were made in a washer fitted with a steam generator. Broth cultures of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, or Streptococcus faecalis (approximately 4 x 10(8) organisms) were sealed in lengths of capillary tubing and attached to the surface of the pans. In other tests, pans were contaminated with an artificial soil containing Str. faecalis (10(8) organisms/ml). In both series of tests, counts of surviving organisms were made at the end of the washing and disinfection cycle. The tests using capillary tubes showed that the Gram-negative bacilli were effectively killed, but not necessarily Gram-positive cocci. However, when incorporated in standard soil, Str. faecalis was killed or removed during the cycle. The results indicate that the disinfection process was effective for metal bedpans, but less so for polypropylene. Possible disadvantages and modification of the machine are suggested.
Protective isolation in single-bed rooms: studies in a modified hospital ward.
Studies were made in a modified hospital ward containing 19 beds, 14 of them in the open ward, one in a window-ventilated side-room, two in rooms with partial-recirculation ventilators giving 7-10 air changes per hour, and two in self-contained isolation suites with plenum ventilation (20 air changes per hour), ultra-violet (UV) barriers at doorways and airlocks.Preliminary tests with aerosols of tracer bacteria showed that few bacteria entered the plenum or recirculation-ventilated rooms. Bacteria released inside mechanically ventilated cubicles escaped into the corridor, but this transfer was reduced by the presence of an airlock. UV barriers at the entrance to the airlock and the cubicle reduced the transfer of bacteria from cubicle to corridor.During a period of 4 years while the ward was in use for surgical and gynaecological patients, the incidence of post-operative sepsis and colonization of wounds by multiple-resistant Staphylococcus aureus was lower (though not significantly lower) in the plenum-ventilated rooms than in the open ward, the recirculator-ventilated cubicles and the window-ventilated cubicles. Nasal acquisition of multiple-resistant Staph. aureus was significantly less common in the plenum-ventilated than in the recirculator-ventilated cubicles and in the other areas. Mean counts of bacteria on settle-plates were significantly lower in the plenum-ventilated cubicles than in the other areas; mean settle-plate counts in the recirculator-ventilated cubicles were significantly lower than in the open ward and in the window-ventilated side-room; similar results were shown by slit-sampling of air. Mean settle-plate counts were significantly lower in all areas when the ward was occupied by female patients. Staph. aureus was rarely carried by air from plenum-ventilated or other cubicles to the open ward, or from the open ward to the cubicles; though staphylococci were transferred from one floor area to another, they did not appear to be redispersed into the air in sufficient numbers to infect the patients. Ultra-violet irradiation caused a significant reduction in the total and staphylococcal counts from the floors of airlocks, and a significant reduction of total counts in the air.
Contamination of infant feeds in a Milton milk kitchen.
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Varieties of aseptic practice in hospial wards.
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Transfer areas and clean zones in operating suites.
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Ward floors and other surfaces as reservoirs of hospital infection.
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Wound infections acquired from a disperser of an unusual strain of Staphylococcus aureus.
Seven post-operative wounds were infected with a strain of Staphylococcus aureus, probably acquired from a theatre orderly who suffered from a dry generalized eczema. The orderly was a nasal and heavy skin carrier, and was shown to be a disperser of the epidemic strain. Infection was probably acquired from airborne contamination in the operating theatre, since the orderly did not scrub-up. The epidemic strain (phage type 80/81 at 1,000 routine test dilution) was sensitive to penicillin and resistant to tetracycline and novobiocin. Neomycin resistance was variable. This strain was found to lose resistance to neomycin when subcultured in the absence of the antibiotic.
Cleaning and disinfection of hospital floors.
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Analytical methods for determination of neat and microencapsulated trichloroethylene in dosing vehicles and whole blood.
Gas chromatographic methodologies were developed for the analysis of microencapsulated trichloroethylene (TRI) in corn oil and feed dosage formulations as well as neat TRI in corn oil and whole blood. Recovery, precision, linearity, and the appropriateness of a linear regression model were evaluated for each method. In all cases recovery was greater than 96% and linearity of the standard curves was confirmed. Good precision and chromatographic resolution were obtained for all samples analyzed.
Liver disease complicating bone marrow transplantation: a clinical audit.
Hepatic dysfunction following bone marrow transplantation (BMT) may present complex management issues. The incidence and aetiology of abnormal liver function following allogeneic and autologous BMT was reviewed over a 2 year period in Royal Perth Hospital and these findings were related to management decisions and patient outcome. Abnormal serum liver biochemistry during the first 12 post-transplant months occurred in all allogeneic (n = 31) and 14 of 23 (61%) autologous transplant patients; 13 (41%) allogeneic and three (13%) autologous patients developed severe hepatic dysfunction. In allogeneic transplants, the most common causes of liver disease were graft-versus-host disease (33%), drug hepatotoxicity (19%) and posttransplant viral hepatitis (15%); in autologous patients, disease recurrence (28%) and sepsis (17%) were the most frequent identifiable cause of abnormal liver function. The aetiology of abnormal liver biochemistry was not determined in 13 instances, but this did not adversely affect patient outcome. Percutaneous liver biopsy or endoscopic cholangiography were only required in three patients. Liver disease contributed to death in two allogeneic patients with multiple causes for liver dysfunction, and in one patient with refractory severe hepatic graft-versus-host disease. It was concluded that hepatic dysfunction is common after BMT, the cause of which can be determined in many cases with simple non-invasive tests used in conjunction with the clinical setting. Specific treatment, where necessary, is then able to be commenced in a majority of patients without the need for invasive investigation.
Segregation analysis of colorectal cancer in Northern Ireland.
The genetic basis for colorectal cancer was investigated by complex segregation analysis of a published series of 305 pedigrees ascertained through a large population database. Two hundred and five of the pedigrees were ascertained through patients diagnosed with colorectal cancer before age 55, and 100 from patients diagnosed with colorectal cancer between the ages of 55 and 74. The analysis was carried out using the program POINTER. Using the joint-likelihood approach, the familial aggregation of colorectal cancer was compatible with the inheritance of a dominant gene. The gene frequency of the putative abnormal allele was 0.002 with a lifetime penetrance of 85%. However, under conditional likelihood, this mode of inheritance for a major gene was not favoured. The possible aetiologies of this paradoxical finding are discussed.
Microbial decontamination in hospitals.
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