Reduced incidence of severe infection after heart transplantation with low-intensity immunosuppression.

Despite advances in immunosuppressive therapy and prolonged graft and patient survival, infection after heart transplantation remains problematic. From January 1987 through June 1989, 104 heart transplantations were performed in 100 patients. Immunosuppression induction was by antilymphocyte globulin for 7 days, with oral cyclosporine introduced on stabilization of kidney function (day 3). Steroid therapy was rapidly tapered, and azathioprine was added only in cases of positive donor crossmatch or steroid-resistant rejection. No reverse isolation was used. Twenty-two deaths occurred, one from sepsis. Actuarial survival at 6 months, at 1 year, and at 2 years was 85% +/- 4%, 81% +/- 3%, and 75% +/- 4%, respectively. Fifty-four patients had 81 infections, of which 21 were bacterial; 83% of these episodes were treated. Sixty infections were opportunistic (85% viral), and only 23% necessitated treatment. Actuarial infection-free rates (all types necessitating treatment) at 1 month, at 6 months, and at 2 years were 83% +/- 4%, 75% +/- 5%, and 75% +/- 5%, respectively. Of the 100 transplant recipients, 66% were treated with azathioprine; 47 patients (69%) had an infection, whereas only seven (19%) of the patients not receiving azathioprine became infected (p less than 0.00001). Rejection was noted in 66% of patients, with a median time to the first episode of 4 weeks. A low-intensity immunosuppressive regimen has resulted in fewer serious infections, with acceptable graft loss from rejection. Increased infection surveillance is required for the first 30 days postoperatively and after treatment of rejection episodes.

Proficiency testing in parasitology. An educational tool to improve laboratory performance.

In 1977, the Laboratory Proficiency Testing Program began testing laboratories that examine samples for gastrointestinal parasites and operated with little change in the subsequent 17 years. Four surveys, each containing four samples, are distributed each year to every currently licensed medical laboratory in Ontario. Participation is mandatory. Survey results indicate a remarkable improvement in laboratory performance during this period. Improvement is believed to result from a combination of the voluntary withdrawal from testing by laboratories with poor performance and the improved performance of the others. The extensive educational services devised and carried out by the Parasitology Committee is believed to have been a significant factor leading to this improvement.

A regional quality control program in microbiology. I. Administrative aspects.

Conventional proficiency testing programs in microbiology using recognizable materials yield limited information. To assess overall laboratory competence in the handling of routine clinical material, other methods are needed. This report describes the use of "blind," simulated clinical specimens in a regional quality control program. Details of the administration, including technics, costs, logistics, and limitations, are presented.

Quality control in bacteriology: preliminary trials.

Six trials of quality control material sent in the form of artificial specimens are reported. A method of assessment using a computer for complex results, including antibiotic sensitivity tests, was employed. The trials were successful in showing the need for a comprehensive service and in bringing to light by this method a wide variety of errors.

Data processing in hospital bacteriology: experience of 18 months' trial.

The nature of bacteriological investigations creates data processing problems. Non-numerical results must be coded. This may be done retrospectively or at the bench, the former method involving extra work and staff, the latter implying simple codes, stringent checking, a nearby computer, and decoding programs. The use of a shared computer for producing daily reports diminishes departmental autonomy. Benefits occur in more readily available records and statistics, quality control, epidemiology, and diagnostic bacteriology.

Fucidin in patients on haemodialysis.

Fucidin is useful against ;antibiotic-resistant staphylococci' which are a major problem in causing shunt site infections in patients on chronic intermittent haemodialysis for end-stage renal failure. A new form of intravenous fucidin has been used in vivo in three patients on haemodialysis, and also in experiments in vitro in order to assess its dialysing properties. The experiments in vitro show that some fucidin does cross the dialyser membrane but, in the patients studied, adequate serum levels were maintained throughout a 10-hour haemodialysis. A single intravenous dose of Fucidin is, therefore, adequate for treating ;antibiotic-resistant' staphylococcal infections in patients during haemodialysis.

System for laboratory proficiency testing in bacteriology: organisation and impact on microbiology laboratories in health care facilities funded by the Ontario Government.

The Ministry of Health requires that all medical laboratories in the Province of Ontario participate in a laboratory proficiency testing program (LPTP). In bacteriology compliance has been excellent. Eighty-six laboratories, for various reasons over the period under review, have surrendered their licence or, because of poor performance on LPTP test surveys, have had their licence withdrawn by the Ministry. The highest percentage of withdrawals occurred in small hospitals in isolated areas. In April 1979 there were 249 participating laboratories. Participants' results are first analysed by computer, and, subsequently, approximately 20% of participants' reports are reviewed by the Committee. Various Committee actions ensue: correspondence with the laboratory director regarding errors; an offer of a visit; and possibly a report via a senior LPTP committee to the Ministry that a laboratory is non-proficient and, in LPTP's terms of reference, non-remediable. Subsequent Ministry action might be the withdrawal of a laboratory's licence. However, this last recourse only occurs when educational efforts have proved ineffectual. Overall, performance in LPTP bacteriology surveys has improved over the period 1975-8, with 68% of 263 laboratories achieving a score of 70% or higher and 26% of 263 laboratories scoring less than 60%.

Pyocin-sensitivity testing as a method of typing Pseudomonas aeruginosa: use of "phage-free" preparations of pyocin.

A method for pyocin-sensitivity typing by means of "phage-free" preparations of pyocin is described. The method was tested on 227 isolates of P. aeruginosa, collected from 34 different foci of infection in hospitals in the British Isles and the results were compared with those for combined serological and phage typing of all strains and pyocin production of 105 of the isolates. It is concluded that pyocin-sensitivity typing is a simple and reliable method giving a high degree of discrimination, comparable to that of combined serological and phage typing, and it is suitable for use in routine hospital laboratories.

Antibiotic resistance of bacteria in water containing ornamental fishes.

Water containing ornamental fishes was found to frequently contain countable numbers of bacteria that were resistant to one or more antibiotic or chemotherapeutic agents. The multidrug-resistant strains most commonly isolated were lactose-fermenting Citrobacter freundii. The overall resistance of these aquaria strains was greater than the previously described resistance of clinical isolates of C. freundii. Although the strains examined appeared to lack R-factors, this pool of resistant bacteria may have public health implications.

Effect of incremental doses of radiation on viability of the microbial population on synthetic operating room gowns.

A total of 700 25-cm2 samples of surgical gown material were exposed to doses of cobalt-60 radiation of 0.0 to 0.6 Mrad in 0.1-Mrad increments. Pour plates were made, and the microbial colonies that arose were enumerated, isolated, and identified as to species. The death rate of the microbial population was calculated, and the mean D10 value of 0.269 Mrad was obtained. Analysis showed that the initial population on unirradiated material had been underestimated; when the counts obtained by homogenization of unirradiated material were substituted, a corrected mean D10 value of 0.249 Mrad was obtained. The isolates obtained were identified, and 70.7% were found to be Bacillus spp. with 12 different species identified, 16.2% were Micrococcus spp. with 6 different species identified, and 8.2% were fungi with 10 different species identified. Calculations were made for appropriate doses of radiation to sterilize gowns with this contaminating microbial population. These calculations gave an estimated dose of radiation of 1.98 to 1.81 Mrad to reduce the observed population to 0.001, a standard where 1 gown in 1,000 might contain a living organism. Comparison of the radiation resistance of this population with that of others reported in the literature showed good agreement.

The rationale and a computer evaluation of a gamma irradiation sterilization dose determination method for medical devices using a substerilization incremental dose sterility test protocol.

The experimental procedure described is designed to allow calculation of the radiation sterilization dose for medical devices to any desired standard of sterility assurance. The procedure makes use of the results of a series of sterility tests on device samples exposed to doses of radiation from 0.2 to 1.8 Mrad in 0.2 Mrad increments. From the sterility test data a 10(-2) sterility level dose is determined. A formula is described that allows a value called DS Mrad to be calculated. This is an estimate of the effective radiation resistance of the heterogeneous microbial population remaining in the tail portion of the inactivation curve at the 10(-2) dose and above. DS Mrad is used as a D10 value and is applied, in conjunction with the 10(-2) sterility level dose, to an extrapolation factor to estimate a sufficient radiation sterilization dose. A computer simulation of the substerilization process has been carried out. This has allowed an extensive evaluation of the procedure, and the sterilization dose obtained from calculation to be compared with the actual dose required. Good agreement was obtained with most microbial populations examined, but examples of both overdosing and underdosing were found with microbial populations containing a proportion of organisms displaying pronounced shoulder inactivation kinetics. The method allows the radiation sterilization dose to be derived from the natural resistance of the microbial population to gamma sterilization.