Ot surveillance


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Ot surveillance

  1. 1. Review article:OT surveillance: Air sampling or Conventional swabbing?!ABSTRACTSurgical site infections (SSIs) are the second to third most common site of health careassociated infections. These complications of surgical procedures cause considerablemorbidity, if these occur deep at the site of the procedure, can carry mortality as high as77 %[1]. There is considerable evidence available to indicate that the surgical site infections area significant health risk to hospital patients. Sources of infection may be either endogenous(from the patient himself) or exogenous from the theatre environment. A large body ofinformation is available which indicates that prevention of post operative infection isdependent on several factors including effective theatre design, sterilisation and disinfectionprocedures, good surgical technique, bacterial contamination of theatre air, discipline whichincludes restricting the movement of staff[2]. Many of debates are extended over on this topicincluding the frequency of microbiological surveillance for operation theatres.Key words: Air sampling, three bucket system, slit sampler, colony forming unitsINTRODUCTION & SITUATION ANALYSIS Even today most of the surgeons are worrying about the OT associated infections withanaerobes like clostridium tetani in most of the instances. Infections with Cl. tetani areassociated with very bad surgical procedures which includes the over jealous manipulations ofthe tissues of surgical site and leaving the dead tissue in the surgical site at the end of theprocedure and also heavy dust in the operation theatre environment. Surveillance for clostridialspores is an age old concept of OT surveillance and lost its importance with the available andapplicable OT sterilization and disinfection awareness programmes and practices. Routine testing for clostridial spores is not mandatory except during certain situations likenew constructions or structural alterations are made to the theatre. But pyogenic infectionsmostly with S.aureus and S.epidermidis are possible even with technically qualitative surgicalprocedures[3]. Healthy carriers have been found to shed staphylococci which is responsible forinevitable airborne contamination. While there is evidence to indicate that most outbreaks arecaused by heavy dispersers[4], every attempt should be made to minimize airborne transmissionwithin operating theatres. Studies in a number of operating theatres have suggested that there is 1
  2. 2. a general relationship between total air count and risk of infection. Counts in the range of700-1800/m 3 were related to significant risk of infection and when they were under 180/m 3 therisk was slight[6]. So prevention of airborne microbial contamination will prevent the surgical site infections.To achieve this basic strategy we should follow the certain guidelines. Which would include, proper and continuing education to staff to prevent shedding of microbes and restrict theunnecessary movements of OT staff within and outside the OT environment.MEASURES TO REDUCE MICROBIAL LOAD IN OT: Fumigation alone cannot sterilize or make the OT environment safe. Failure to provideadequate operation theatre ventilation is associated with risk of postoperative infections.Theatre ventilation has been found to be a critical factor in prosthetic and joint surgery[6].While maintaining the proper ventilation ,we have to be careful about the microbial load in theOT environment .Filtration of OT air by fitting the HEPA filters are mandatory to fulfill theabove criteria. Since the operation theater environments are the dynamic, good equipment andarrangements are only not safe since it becomes unsafe because of human activities. Cultureswabs from unnecessary surfaces of OT environment (roof, upper parts of wall) may causesconfusion during the interpretation of the results[4]. Dust should be removed with cloth wettedwith clean water Chemical and disinfectants should not be used as habit.. Chemical agents ordisinfectants or detergents should be used when OT floor and surfaces are contaminated withblood and body fluids.Swabbing the surfaces with suitable commercially available disinfectantBacillocid (Mixture of dihydroxy formaldehyde, glutaraldehyde and bezalkonium chloride) byusing the three bucket system will remove the majority of the microbes. • 1st Bucket with water: Dirty mop is rinsed • 2nd Bucket with fresh water for rinsing: Mop rinsed again in this water • 3rdBucket with suitable disinfectant: Mop is immersed in the solution and floor should be mopped liberally. Wash the used mop with disinfectant after use and dry.STANDARD GUIDELINES AND PLANNING FOR AIR SAMPLING: There are no nationally agreed standards for any country or place regarding when toundertake microbiological sampling in the operating theatre and on the interpretation ofsampling results[5]. However, there is sufficient evidence to support the undertaking ofmicrobiological air sampling in the operation theatre as part of the vigilance & safety of anoperating theatre, after any major structural replacements (not including High EfficiencyParticulate (HEPA) filter changes and as deemed necessary by the hospital infection controlcommittee. Health care workers should follow certain guidelines before air sampling. Prior toair sampling, obtain the suitable air sampling equipment from a laboratory, establish laboratory 2
  3. 3. time-lines for sample collection, processing and provision of results and should not ignore toconsult the hospital microbiologist or infection control unit.HOW TO DO THE AIR SAMPLING?. Bacterial counts in operation theaters are influenced by the number of individuals present,ventilation and air flow methods. Air sampling should be done after the all new or replacementwork has completed. The ventilation system should run continuously for 24 hours beforesampling and the theatre surfaces and fixed equipment, ducting and air diffuser plates have tobe cleaned. Settle plate method by using blood agar is being practiced in basic hospitals to detect allkinds of bacteria in hospital air. Settle plate method with blood agar where the plates have tokeep at 2 ½ feet height on the four corners of room and results are obtained based on the meancolony number on the all culture plates after a prescribed time. Because of recent advances incertain surgical procedures and bacterial counts settle plate method is replaced with Slitsampler and Air centrifuge equipment through which we can calculate the safe levels ofcolony counts. There are several different types of air samplers available and themanufacturer’s instructions for use must be followed. If affordable, the preferred method is touse a sampler with timer and remote control.RECOMMENDED METHOD FOR AIR SAMPLING [6]:1. A single sample should be collected from each operating theatre.2. The air sampler should be checked for cleanliness before use by following the manufacturer’s instructions.3. The theatre being sampled should have been left vacant for a minimum of 15 minutes, preferably one hour. To avoid false-positive results the theatre doors must be kept closed prior to and during the sampling period .4. Staff should wear theatre attire and a surgical mask, with proper hands wash and surgical gloves.5. Place the agar strips or plate into the sampler under aseptic precautions and set up the equipment.6. The air sampler should be placed in the middle of the theatre table at the height of 2.5 feet and to be secured on a trolley.7. The air sampler should then be switched on either by remote control or manually, before leaving the room.8. The sampling equipment will determine the volume of air sampled. Sampling volume needs to be more than 0.25 m3 (250 L) and optimally around 1m3 (1000 L).9. Once sampling is completed, remove the test strips/agar plate aseptically and 3
  4. 4. label it clearly and send it the processing environment.RESULTS AND INTERPRETATION: Culture plates should be incubated under optimum conditions in the microbiologylaboratory. Early culture reports hardly available until after 24 hours of incubation. Aerobiccultures on non-selective medium (preferably Blood agar) should not exceed 35 colony –forming units of bacteria and fungi per cubic meter of air for a conventional theatre and 1cfufor an ultra clean theatre to perform joint replacement and cardiac surgeries[1]. These countsare not rigid standards and are intended as a guideline only. Even though the swabs are takenfor OT surveillance to isolate and identify the clostridial spores, air sampling is must tomeasure the safer load of microbes. In some of the hospitals OT sampling is done by swabbingand plating on the blood agar and results are being announced after 24-48 hours of aerobicincubation. By the above mentioned method quantitative estimation of the microbial load is notpossible. Literature which is supporting for this kind of practice is not available from varioussources. Moreover, this type of cultures on non-selective medium will create unnecessaryconfusion while detecting OT sterilization status and which should be abandoned.REFERENCES:1. Davis N., Curry A, Gambhir AK, Panigrahi H, Walker CR, Wilkins EG, Worsley MA and Kay PR Intraoperative bacterial contamination in operations for joint replacement. J Bone Joint Surg Br 1999; 81-B:886-9.2.Colquun J, Partridge L. Computational Fluid Dynamics Applications in Hospital Ventilation Design. The Austrilian Hospital Engineer 2003 ; 26 (1) 35-40.3.Guidelines to standards for operating rooms. located at. http://www.health.wa.gov.4.Geeta Mehta. Microbiological surveillance of operation theatre – 2005. http://www.orthoteers.org.5.Dharan S, Pittet D. Environmental controls in operating theatres. J Hosp infect 2002; 51(2) 79-84.6.Department of Health, Western Australia . Private Hospital Guidelines, 3rd edition. 1998. http://www.health.wa.gov. 4