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Biomedical subjects

E J Lowbury

Publications and source records attributed to E J Lowbury.

At least 19 recordsLinked to original sources

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.

Air Microbiology↗

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.

Anti-Bacterial Agents↗

Trial of a laminar air-flow enclosure for the control of infection in a burns operating theatre.

A series of 22 patients with full-skin thickness burns had skin grafting operations in a Piekenrood-Vinitex BV open-topped laminar air-flow enclosure, and a parallel control series of 18 patients were grafted in the same operating room without the use of the laminar flow unit; the operating room in which both series of operations were performed had standard plenum ventilation with 20 air changes per hour. None of the patients acquired on their burns Staph. aureus of phage types and antibiotic sensitivity patterns corresponding with those isolated from carriers who were in the theatre at the time of the operation; 16 patients acquired on their burns strains of types corresponding with those of strains isolated from burns of other patients in the ward. Settle plates exposed during operations showed a relatively small reduction in bacterial counts associated with the use of the laminar flow enclosure.

Burns↗

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)

Air↗

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.

Air Microbiology↗

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.

Air Microbiology↗

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).

Air Microbiology↗

Decline of the hospital Staphylococcus? Incidence of multiresistant Staph. aureus in three Birmingham hospitals.

The prevalance of antibiotic-resistant strains of Staphylococcus aureus was studied in three Birmingham hospitals. In a general hospital periodic surveys showed a progressive decline in the proportions of patients with Staph. aureus in their noses which were resistant to tetracycline, erythromycin, and kanamycin. This change was associated with a progressive reduction in the use of tetracycline without an overall reduction in the use of antibiotics. There was no similar decline in resistance of staphylococci isolated in a hospital for skin diseases. In a burns unit there was a sudden large reduction during September, 1978, in the proportions of Staph, aureus from burns which were resistant to tetracycline, methicillin, cephaloridine, erythromycin, lincomycin, novobiocin, gentamicin, and kanamycin, and in the proportions of multiresistant strains (resistant to penicillin, tetracycline, erythromycin, kanamycin, methicillin, novobiocin, cephaloridine, and lincomycin). This change was associated with a reduction in the number of patients and in the use of antibiotics; tetracycline was not in use except during one month of the study. Strains of Staph. aureus resistant to these antibiotics became common again in the burns unit when a larger number of patients were admitted and more antibiotics were used in the wards.

Anti-Bacterial Agents↗

Gentamicin- and silver-resistant pseudomonas in a burns unit.

In 1977-8 gentamicin-resistant strains of Pseudomonas aeruginosa became very common in a burns unit, over 90% being resistant at the peak of the outbreak. Some strains were also resistant to silver nitrate, though silver resistance was not found in any other strains of Ps aeruginosa isolated. Unlike the gentamicin resistance, the silver resistance was unstable, and strains became sensitive on repeated subculture. All the gentamicin-resistant strains of Ps aeruginosa were of the same serotype (O:11, H:2,5). Though gentamicin resistance could be transferred in vitro from resistant strains of Ps aeruginosa to one sensitive strain of Ps aeruginosa, there was no evidence of in-vivo transfer of gentamicin resistance between strains of pseudomonas in the patients' burns, nor was there evidence of transfer of gentamicin resistance between Ps aeruginosa and enterobacteria. Carbenicillin-resistant and gentamicin-resistant Ps aeruginosa were sometimes found in the same burns, but no gentamicin-carbenicillin (doubly) resistant strains were found among the 986 strains tested during the outbreak. The outbreak of gentamicin-resistant Ps aeruginosa from burns was not reduced by stopping treatment with gentamicin and its analogues but only by segregating all patients with Ps aeruginosa in one of the two wards of the unit and admitting new patients only to the other ward.

Burns↗

Detergents compared with each other and with antiseptics as skin 'degerming' agents.

Three detergent preparations (bar soap, 'Hibiscrub' base and 'LIC 76'), TWO ANTISEPTic preparations (0.5% chlorhexidine in 95% ethyl alcohol and an alcohol jelly, 'Alcogel'), and one antiseptic-detergent solution (4% chlorhexidine gluconate in a detergent base, 'Hibiscrub') were compared for their effectiveness, on a single use, in reducing the yield of bacteria from the hands of volunteers. The antiseptic and antiseptic--detergent preparations were more effective than the detergents, with a mean reduction in yield of skin bacteria of 96.0% after use of alcoholic chlorhexidine and of 81.2% after use of Hibiscrub. One of the detergents, LIC 76, appeared more effective than the others, causing a mean reduction in the yield of skin bacteria of 41.5%, compared with reductions of 4.6% by the Hibiscrub detergent base and an increase of 3.2% with bar soap; unlike the other detergents, LIC 76 was found to have appreciable bacteristatic and bactericidal properties.

Bacteria↗

Staphylococcal sepsis in a burns unit.

An outbreak of staphylococcal sepsis in a burns unit occurred between January 1976 and May 1978. Many patients and members of staff had boils, and a number of patients also developed septicaemia. Most of the boils in the early period of the trial and a large proportion of boils in patients during the later period yielded Staphylococcus aureus resistant to penicillin, tetracycline and erythromycin only (PTE), and were shown to be of phage type 95 in the early period while strains were phage typed. From blood cultures, most strains in the early period were of resistance pattern PTE and phage type 95, but in the later period other resistance patterns were predominant. Strains from burns were usually multiresistant (PTEKNML) and of the phage pattern 29/77, which had been endemic in the Unit, but during the early period of the outbreak there was an increased proportion of strains in burns with the resistance pattern PTE and of phage type 95. Staphylococcal sepsis has for many years been very infrequent in the burns unit. This outbreak seems to have been initiated by a strain of phage type 95 and resistance pattern PTE, but during the course of the outbreak the endemic strain of type 29/77 and some other staphylococci seem to have developed enhanced ability to cause clinical infections, conceivably by transduction from the epidemic strain of phage type 95.

Burns↗

Delayed antimicrobial effects of skin disinfection by alcohol.

Aqueous suspensions of Staphylococcus aureus were deposited on a Millipore filter and then exposed for a few seconds to 70% ethyl alcohol. Viable counts of bacteria extracted from the filter immediately after exposure to alcohol, and, in replicate experiments, after a further period of 3 h, showed that the mean immediate reduction of 97.6% in viable counts after treatment with alcohol was followed by a further mean reduction of 67.1% in the further 3 h holding time; the same bacterial suspensions allowed to dry on Millipore filters without exposure to alcohol showed a significantly smaller mean reduction in viable counts (34.3%) during a further 3 h holding time. These findings support the view that the reported further fall in numbers of bacteria on hands while wearing gloves for 3 h after alcohol disinfection can be explained by sublethal damage to some of the bacteria, from which they can recover only if promptly inoculated on culture medium.

Antisepsis↗