Ultraclean air and antibiotics for prevention of postoperative infection. A multicenter study of 8,052 joint replacement operations.

To determine the value of ultraclean air in operating rooms, 8,052 operations for total hip- or knee-joint replacement were followed up for 1-4 years. For operations done in ultraclean air, bacterial contamination of the wound, deep joint sepsis, and major wound sepsis were substantially less than for operations done in conventionally ventilated rooms. Sepsis was also less frequent when prophylactic antibiotics had been given. The two precautions acted independently so that the incidence of sepsis after operation in ultraclean air and with antibiotics was much less than that when either was used alone. Wound sepsis was associated with an enhanced risk of joint sepsis. Staphylococcus aureus was the commonest joint pathogen, but infections with other organisms, often considered to be of low pathogenicity, were almost as numerous. Most S. aureus infections were traced to sources in the operating room.

Extended follow-up of patients suspected of having joint sepsis after total joint replacement.

During an average follow-up time of about 2 1/2 years after total hip or knee-joint replacement in 8052 patients, suspected joint infection was recorded in 85 patients whose joints had not been re-operated during that period. The hospital records of 72 of these patients were examined after a further period, averaging about 5 years. Thirty-five of these had suffered continuing major problems with the joint, 18 of which had been revised, and a further 9 joints needed such treatment. Infection was confirmed in 17 of the 35. These numbers are proportionately about three times greater than those observed among a set of matched controls followed-up for a similar period. The evidence from the extended follow-up suggests that the failure rate, unassociated with infection, reached about 5% by 7 years after operation and that late infections, manifested between about 2 1/2 and 7 years after operation, were about as frequent as those confirmed during the first 2 1/2 years.

Infection and sepsis after operations for total hip or knee-joint replacement: influence of ultraclean air, prophylactic antibiotics and other factors.

Operating in ultraclean air and the prophylactic use of antibiotics have been found to reduce the incidence of joint sepsis confirmed at re-operation, after total hip or knee-joint replacement. The reduction was about 2-fold when operations were done in ultraclean air, 4.5-fold when body-exhaust suits also were worn, and about 3- to 4-fold when antibiotics had been given prophylactically. The effects of ultraclean air and antibiotics were additive. Wound sepsis recognized during post-operative hospital stay was, however, reduced by these measures only when it had been classed as major wound sepsis. This was reported after 2.3% of operations done without antibiotic cover in conventionally ventilated operating rooms. Joint sepsis was much more frequent after wound infection and especially after major wound sepsis, although most cases of joint sepsis were not preceded by recognized wound sepsis. This was particularly noticeable after major wound sepsis associated with Staphylococcus aureus; after 37 such infections the same species was subsequently found in the septic joint of 11 patients. The sources of wound colonization with Staph. aureus, when this was not followed by joint sepsis, appeared to differ widely from those where joint sepsis occurred later. Operating-room sources could be found for most of the latter and the risk of infection appeared to be similar with respect to any carrier in the operating room whether a member of the operating team or the patient. For wound colonization that was not followed by joint sepsis, operating-room sources could only be inferred for fewer than half and of these more than one half appeared to be related to strains carried by the patient at the time of operation. During the follow-up period, which averaged about 2 1/4 years with a maximum of four years, there were, in addition to the 86 instances of deep joint sepsis confirmed at re-operation, 85 instances in which sepsis in the joint was suspected during this period but was not confirmed, because re-operation on the joint was not done. The incidence of suspected joint sepsis was, like that of confirmed joint sepsis, less after operations done in ultraclean air: 1/2.5, or with prophylactic antibiotics, 1/2.3 Although re-operation was more frequent on the knee-joint than on the hip, and pain after the initial operation was more frequent after knee operations, there was no evidence that this was the result of any increased risk of infection.(ABSTRACT TRUNCATED AT 400 WORDS)

Airborne contamination of wounds in joint replacement operations: the relationship to sepsis rates.

During operations for total joint replacement done in operating rooms with conventional ventilation the mean air contamination varied considerably among the 15 hospitals studied. The range was from 51 to as many as 539 bacteria-carrying particles per cubic metre. When the data from all the hospitals were grouped according to the mean level of bacterial airborne contamination, including operations done in control and in ultraclean air, there was a good correlation between the air contamination and the joint sepsis rate. There was also a correlation between the mean values of air contamination and the numbers of bacteria isolated from wound wash-out samples; but the apparent efficiency of the sampling method varied a great deal among the hospitals carrying out this procedure. From this data it would seem that by far the largest proportion of bacteria found in the wound after the prosthesis had been inserted reached it by the airborne route. With the mean air contamination found in the control series, 164 bacteria-carrying particles per cubic metre, this proportion was as much as 95 per cent. The risk of joint sepsis varied widely among the 19 hospitals. The differences between the highest and lowest being probably as much as 20-fold. However, the effect of an ultraclean air environment was asimilar at all hospitals.

Suggested bacteriological standards for air in ultraclean operating rooms.

Bacteriological standards for the air in ultraclean operating rooms are needed since physical tests alone cannot guarantee satisfactory results. 10 m-3 is suggested as the highest acceptable value for an ultraclean system. Methods are described for determining this.

Bacteria isolated from deep joint sepsis after operation for total hip or knee replacement and the sources of the infections with Staphylococcus aureus.

A wide variety of bacterial species, many usually regarded as of low pathogenicity, were isolated from septic joints after operation for total hip or knee joint replacement in a multi-centre trial of ultraclean air in operating rooms. The prophylactic antibiotics generally used appeared to reduce considerably the rates of infection with most species but to be ineffective against 'gut' organisms. For about half the septic infections involving Staphylococcus aureus nasal swabs had been obtained from the patient and operating staff at the time of operation for insertion of the prosthesis. Strains of Staph, aureus isolated from these and from the infected joints were phage typed and tested for antibiotic sensitivity. A probable source among the carriers was found for seven out of the 14 infections and a possible source for another five. Very small numbers of Staph. aureus were needed to initiate infection.

Effect of ultraclean air in operating rooms on deep sepsis in the joint after total hip or knee replacement: a randomised study.

In a multicentre study of sepsis after total hip or knee replacement the operations performed by each surgeon were allocated at random between control and ultraclean-air operating rooms. Records were obtained from over 8000 such operations. In the patients whose prostheses were inserted in an operating room ventilated by an ultraclean-air system the incidence of joint sepsis confirmed at reoperation within the next one to four years was about half that of patients who had had the operation in a conventionally ventilated room at the same hospital. When whole-body exhaust-ventilated suits had been worn by the operating team in a theatre ventilated by an ultraclean-air system the incidence of sepsis was about a quarter of that found after operations performed with conventional ventilation. When all groups in the trial were considered together the analysis showed deep sepsis after 63 out of 4133 operations in the control group (1.5%) and after 23 out of 3922 operations in the ultraclean-air groups (0.6%) (ratio 2.6, 95% confidence limits 1.6-4.2; p less than 0.001). The design of the study did not include a strictly controlled test of the effect of prophylactic antibiotics, but their use was associated with a lower incidence of sepsis than in patients who had received no antibiotic prophylaxis at their operations (0.6% (34/5831) v 2.3% (52/2221); ratio 4.0).

An isolation unit in a district general hospital.

The working of a 19-bed isolation unit in a general hospital was studied from August 1975 to July 1976. A few patients received the highest degree of isolation, but infections in all categories were contained and patients at risk in the same unit were protected from infection.

Diffusion of antibiotics from acrylic bone-cement in vitro.

The diffusion of Fucidin, gentamicin, and clindamycin from acrylic cement was tested in an in vitro system. The activity of Fucidin was very short-lived and only against gram-positive organisms; gentamicin inhibited gram-positive and gram-negative organisms for twenty-two and eleven days respectively; clindamycin had significant action only against gram-positive organisms and retained some activity for fifty-six days. We suggest that the destruction of organisms in the tissues is more likely to be achieved by topical and intravenous administration of antibiotics during the operation than by incorporation of antibiotic in the cement.