The conventionally ventilated operating theatre and air contamination control during cardiac surgery--bacteriological and particulate matter control garment options for low level contamination.

OBJECTIVE: The purpose of the study was to compare the usefulness of a conventional bacteriological technique with that of particle counting under lower air contamination and better aseptic conditions achieved with special staff garments and covering for the patient. Contamination levels were estimated with continuous on line air particle counting measurement, volumetric intermittent short period aerobic bacteriological cultures and wound surface contact cultures. METHODS: In a series of 66 consecutive coronary artery bypass operations performed by the same team and in the same theatre using different types of patient and staff clothing, the impact of a reduced bacteriological and particulate contamination were assessed. The volumetric air contamination of particles > or =5 microm and bacteria-carrying particles were monitored 30 cm above the sternal wound. The bacterial contamination and bacterial wound infections in the sternal and leg wounds were assessed as well. RESULTS: With the alternative garment and textile system, the air counts fell from 25 colony-forming units (CFU)/m3 to 7 CFU/m3 (P < 0.0038). The contamination of the sternal wound was reduced by 46% and that of the leg wound by >90%. In order to give continuous contamination feedback during the whole operation to the theatre staff, particle counts > or =5 microm were monitored and visualized. Air particle counts decreased rapidly from 850 particles/m3 and stabilized to approximately 50 particles/m3 when the alternative clothing system was used (P < 0.001). Low particle counts > or =5 microm should offer the possibility to indirectly estimate air bacteria carrying particle counts during the entire operation. Less than 20% of the total count in this size group carries bacteria. The low air contamination was achieved even in an ordinary ventilated theatre when individual team members used clean air suits in combination with impermeable patient drapes. When air particle level < or =50 particles/m3 is reached, the bacterial air contamination is in the order of that of orthopaedic hip operations. The staff must during the entire operation adjust their activity to air asepsis. CONCLUSIONS: The use of clean air suits and impermeable patient clothing results in a low exogenous contamination of air and wound. Continuous air particle monitoring is a good intraoperative method to monitor the air contamination longitudinally in an operating theatre.

Air contamination during hip and knee arthroplasties. Horizontal laminar flow randomized vs. conventional ventilation.

In a randomized study 90 patients, operated on with a total hip or knee arthroplasty, were allocated to 1 of 3 different regimes, all including a reinforced single-use operating gown: (1) horizontal laminar flow ventilation and conventional clothes (cotton shirts and trousers) for all staff members, (2) horizontal laminar flow ventilation and occlusive garments (Klinidress) and (3) conventional ventilation and occlusive garments. Volumetric air sampling gave a low mean number of colony-forming units (< 10 cfu/m3) in the vicinity of the wound in all 3 groups. Laminar ventilation, with or without occlusive staff garments, resulted in less air contamination compared to conventional ventilation. During knee arthroplasty, the use of occlusive clothes in the laminar ventilation room, further reduced the number of airborne, bacteria-carrying particles to around 1 cfu/m3. No such reduction was seen during hip arthroplasty. We conclude that hip and knee arthroplasties can be performed in operating theaters with conventional ventilation when occlusive staff garments are used. However, laminar air flow ventilation in knee surgery, preferably in combination with occlusive garments, resulted in a substantially lower air contamination and should be preferred.

The microbial flora in venous leg ulcers without clinical signs of infection. Repeated culture using a validated standardised microbiological technique.

The change of ulcer size in relation to the presence of species and quantities of microorganisms was analysed in 58 patients with venous leg ulcers, all without clinical signs of infection. Microbiological samples were taken on the day of inclusion and then repeated 4 times at monthly intervals or until the ulcer had healed or was too small to be cultured from. There was growth of microorganisms in all ulcers, and the numbers were below 10(4) per mm2 of ulcer surface in all cases. No correlation was found between ulcer size change and the species and amounts of microorganisms. Sixty-nine species were isolated. Staphylococcus aureus was found in 88%, Enterococcus faecalis in 74%, Enterobacter cloacae and Peptococcus magnus in 29%, and fungi in 11% of the samples. One or more obligate anaerobe species was found in 41% of the samples and in half of the ulcers and constituted 62% of all bacterial species. The colonising ulcer flora was markedly constant over time in the individual ulcers regardless of change in size. Resident bacterial species were found in 57 of the 58 ulcers. If all samples were considered, the microorganisms were associated with not more than one fifth of the variability in healing rate, as shown by linear multiple regression analysis. The same species of microorganisms were found in ulcers that decreased (or healed) and in those that increased in size. Although an association between the microorganisms and ulcer healing could not be ruled out in this study, there seems to be no indication for routinely performed culture in the absence of clinical signs of infection in venous leg ulcers.

The relative importance of the routes and sources of wound contamination during general surgery. II. Airborne.

The influence of airborne bacteria on wound contamination during biliary surgery was studied. When bacteria grew in the bile they accounted for most of the bacteria in the wound but when the wounds were free of bile bacteria many of the bacteria came from the patient's skin. It was only in wounds with little contamination from non-airborne routes that it was possible to demonstrate an effect of airborne contamination. In such a situation it was estimated that a reduction in the airborne bacteria in the operating room of about 13-fold would reduce the wound contamination by about 50%. The contamination of patient drapes from various sources and its relationship to wound contamination was studied. It was demonstrated that in areas away from the wound, the bacterial concentration on the drape surface was significantly affected only by airborne bacteria. In the area close to the wound, airborne bacteria and bacteria from the wound significantly affected drape contamination. However, it was found that more bacteria transferred from the wound to the drape surface than vice versa. Punctured gloves, impervious gowns and the number of bacteria on the patient's skin did not significantly affect the counts on the drapes' surfaces.

Ultraviolet radiation compared to an ultra-clean air enclosure. Comparison of air bacteria counts in operating rooms.

Clean air in the operating room is important during joint replacement surgery. We compared monochromatic ultraviolet radiation of 254 nm with the use of a Charnley-Howorth air enclosure by bacterial air-sampling during 113 total hip arthroplasties. Air samples were taken continuously at the edge of the wound and every 15 minutes at a site 130 cm from the operating table. We also tested the effect of occlusive clothing for all personnel. Ultraviolet light was more efficient than the ultra-clean air enclosure, and occlusive clothing on its own or in combination also produced improvement. The implications of these findings are discussed.

Radiation resistance of microorganisms on unsterilized infusion sets.

Three different methods were used for detecting and isolating microorganisms with high radiation resistance from the microbial contamination on infusion sets prior to sterilization. By all three methods, microorganisms with a radiation resistance high enough to be a critical factor in a sterilization process (D-6 value greater than or equal to 30 kGy) were found with a frequency of approximately two colony forming units (cfu) per 100 product items, even though the product items in two of the series of analyses were irradiated with doses of 3-6 kGy. The frequency of occurrence of isolates with D-6 values greater than or equal to 30 kGy was 0.45 per 1000 cfu of the total aerobic count. Eight different isolates of microorganisms had D-6 values greater than or equal to 40 kGy when irradiated in dried laboratory preparation. All but one of these were classified according to morphologic criteria as Deinococcus, and all but one had nonlinear dose-response relationships in semilogarithmic presentation.

The relative importance of routes and sources of wound contamination during general surgery. I. Non-airborne.

A study was undertaken to determine the relative importance of some sources, routes of transmission, and measures to prevent bacteria entering the wound during biliary tract surgery. When bacteria were growing in the bile they accounted for the majority (greater than 99%) of the bacteria found in the wound. However, when the bile was sterile the skin bacteria at the incision site were found to make a substantial contribution to the wound flora. The difference in the total wound contamination between a patient who had practically no skin bacteria and one who had an average amount was in the region of 17-fold. No transfer of skin bacteria from the surgical team through perforated gloves or by direct contact from the surface of operating gowns was demonstrated. Ten of the patients studied had septic wounds. Five of these were infected by bacteria from the bile.

Influence of drape permeability on wound contamination during mastectomy.

Sixty-one patients undergoing mastectomy at three hospitals were randomly allocated to receive one of three types of drape: permeable linen sealed to the skin with self-adhesive nonwoven tape, and impermeable nonwoven with self-adhesive edges. Bacteriological contamination was assessed both in the wound and in the wound surroundings. The air counts at the centres differed but were generally low, mean approximately 10(1) colony-forming units (CFU)/m3 but higher at the beginning of the operation. Patients whose skin counts were high before disinfection had the highest skin counts after disinfection and operation and gave the highest counts on the gloves of the surgeon. The use of impermeable drapes instead of permeable linen drapes resulted in significantly fewer bacteria in the operative field (393 CFU/50 cm2 compared with 664, p less than 0.002) and also in the wound itself (12 compared with 164 CFU/sample, p less than 0.01). As a result of correlations between counts, we are also able to show how bacteria transfer from the patient's skin to the surgical wound.

Reduction of contamination at total hip replacement by special working clothes.

We assessed wound, air and operative field contamination at 50 total hip operations, performed in a zonal ventilation system. Theatre staff wore either a specially designed polypropylene non-woven coverall or conventional cotton shirt and trousers. The surgeons wore partially impermeable operating gowns. The polypropylene coverall was associated with significantly lower air and wound counts. The coverall was warmer than cotton but judged to be acceptable. The combined use of zonal ventilation and the coverall achieved ultra-clean air conditions.

Air contamination in open heart surgery with disposable coveralls, gowns, and drapes.

The effect of a polypropylene coverall, replacing shirt and trousers, combined with sterile laminated gowns and drapes compared with an all-cotton system was studied in regard to the dispersion of bacteria and particles in a conventionally ventilated operating theater. The operations carried out were open heart procedures in 30 adult patients. Blood agar sedimentation plates were placed in the operative, anesthesia, and perfusion areas. The mean sedimentation values during 1 hour after the start of operation were as follows in the laminate group: 63 colony-forming units (cfu)/m2 in the operative area; 77 cfu/m2 in the anesthesia area; and 143 cfu/m2 in the perfusion area. The corresponding figures in the cotton group were 350 cfu/m2, 364 cfu/m2, and 437 cfu/m2, respectively (p less than 0.0002). At the beginning of the operation, the mean values noted for colony-forming units in the air at the operative site were 8.0 cfu/m3 in the laminate group and 31 cfu/m3 in the cotton group. One hour later, the values were 10 cfu/m3 and 22 cfu/m3, respectively (p less than 0.0002). At the end of the operation, the number of particles 5 microns or larger in the air at the operative site was 278/m3 in the laminate group and 592/m3 in the cotton group. It is concluded that the use of a polypropylene coverall and laminated gowns and drapes significantly reduces the particle and bacterial contamination of the air and the bacterial sedimentation during cardiac operations.

Skin sampling-validation of a pad method and comparison with commonly used methods.

Two types of pad were tested for sampling bacteria from the skin. One pad was made of 85% viscose and a 15% mixture of polyester and polyamide fibres, the other was made of polyvinyl-alcohol foam. The efficiency was calculated using double samples and 8 consecutive samples. The two pads were equally efficient and more efficient when moist. Their efficiency was compared with that of the bud swab, the Rodac plate and the scrub cylinder method. Using the double sample method for calculation, the scrub cylinder method and the pads were equally efficient, around 50%. As calculated from consecutive samples the efficiency of the pads was about 45%, the efficiency of the cylinder scrub method 29%, and that of the bud swab and Rodac plate 16% and 5% respectively. The low efficiency of the Rodac plate may be partly explained by the fact that microcolonies and not bacterial cells are sampled with this method.

Shortwave ultraviolet radiation in operating rooms.

We have evaluated the effect of shortwave ultraviolet radiation on bacterial levels in an operating theatre, both in experimental conditions and during 20 hip operations. When compared with the use of sham blue light, there was a significant reduction in the number of bacteria. The reduced level was comparable with that suggested for ultraclean air ventilation systems.

Packaging. Manufacturers' considerations.

Central sterilization services have changed significantly over the years, while the health care industry has grown. Mölnlycke being a manufacturer of mostly soft goods products for use in the operating theatre as well as for wound care may not be able to contribute to the in house production but rather to give views on two other important tasks for the CSSD namely the handling and distribution of industrial sterilized medical devices and surgical products and also the application of GMP within the service.

Bacterial counts on fabrics: a comparative study of three methods.

One contact plate and two homogenization methods have been compared for efficiency in assessing the bacterial contamination of fabrics with high or low, natural or artificial contamination. The contact plate method resulted in considerably lower counts than any of the homogenization methods, which closely resembled one another. One of these, utilizing a Stomacher 400, was found to be more practical, and is therefore recommended for counting bacteria on fabrics.

Patient draping and staff clothing in the operating theatre: a microbiological study.

Fallout of bacteria and contamination at the wound site were studied during a standardized orthopaedic operation using sedimentation plates and a bacterial sampler. The procedure was performed in either a conventionally ventilated operating theatre or in an ultraclean air enclosure. The staff was dressed in either an all-cotton system (working clothes and theatre gown) or cotton working clothes in combination with Ventile theatre gown, or a laminate disposable theatre gown, or finally a polypropylene coverall and a laminate theatre gown. The patients were draped in cotton or laminate. The study was done during 5 periods. The most striking effect was seen when the combination of the coverall and the laminate theatre gown was used. The fallout in the conventional theatre was then at the same level as in the ultraclean air. It was even less than using Ventile gowns and laminate drapes in ultraclean air. The contamination at the wound site showed the same pattern. However, least contamination was recorded when laminate gowns and laminate drapes were used in ultraclean air.

Steam sterilization: a comparison of Steam-Clox and some european biological indicators.

Results of a study of the reaction of a chemical indicator (Steam-Clox) and of two biological indicators exposed to steam sterilization with varying amounts of air introduced with the steam, indicate that the chemical indicator is capable of detecting significantly smaller amounts of air than either of the biological indicators tested.