Introduction• Devastating surgical complication.• Although reduced now• CHALENGING PROBLEM• Costly – patient & health care system.
Historical Aspects• Pringle 1750 – “Antiseptic”• Isaac Benedict Prevost 1807 – first proof ofmicroorganisms as the causation of sepsis.• Louis Paster 1863 – Putrifaction is caused bymicrobes from air.• Joseph Lister – used antiseptic soln to preventputrifaction & demonstrated that pus is adisaster rather than a sign of healing.
• Lister’s technique of sterilization, skinpreparation and washing became –Foundation of “Antiseptic Surgery”.• First step in development of“Asepsis in surgery”.• Introduction of antibiotics 1940 –Streptococcal hospital infection disappeared.• 1950s World wide epidemic of nosocomialinfection by Virulent resistant Staphylococcus.
Nosocomial Infection• Develops during hospitalization• Neither present nor incubating at the time ofpatients admission.• 50% involve surgical site infection.
National Nosocomial Infection Surveillance(NNIS)• Current version for SSI risk index scores eachoperation by counting the risk factors:1. Type of wound2. ASA score of 3,4 or5 (Host defense)3. Duration of surgery – lasting more than T-hours
Surgical site infection• Postoperative wound developing signs ofinflammation or serous discharge is labeledas “possibly infected”.• Cruse et al 1977 classified wounds – 4categories1. Clean wound:• No infection, no break in aseptic technique & nohollow muscular organ opened.
2. Clean contaminated wound: Hollow muscular organ opened with minimalorgan spillage.3. Contaminated wound: Hollow organ opened with gross spillage, acuteinflammation without pus, traumatic woundswithin 4 hours and major break in aseptictechnique.
4. Dirty wound: Perforated viscus, pus, traumatic wound more than 4hours old.• INFECTION RATE1.57.715.24005101520253035401st QtrCleanClean contaminatedContaminatedDirty
• Infection in clean wounds – Surveillance &research.– < 1% Ideal.– 1-2% can be acceptable.– > 2% cause of concern.• Monthly announcement– Everyone aware ofSSI– Can reduce by 38% by appropriate feedback.
Rate of infection• Purely a statistic for the surgeon.• Total DISASTER for the patient.• Sir Watson Jones 1962 – “Infection of oneclean case in a thousand is a disaster of thefirst magnitude”.• Even slight delay in healing, redness of skin, orany other sign of wound infection – evidenceof failure.
Orthopaedic clean wound• Too many variables– Surgery of soft tissues alone or of bones– With or without implants– Emergency trauma or planned trauma cases– Timing of surgery in trauma– Reaming of medullary canal, primary plating.– Stable and unstable fixation.
Post Operative infection?• Primary or secondary?• Possible to predict?• High risk patients?• Possible to prevent in best possible operativeconditions?
• All operative wounds get contaminatedduring surgery – does not mean infection.• Sources of contamination:1. Surgeon & his team2. Air in OT3. Skin of patient & all OT personnel.• Conversion of this contamination toinfection is to be avoided.
Depends upon:• Virulence of the organisms• Degree of contamination• Presence of dead & devitalized tissue,implants & suture material.• Site of operation i.e. bone• Duration of surgery• HOST RESPONSE – Immunological status
SSI• Story of germination of a seed in soil.• 95% of bacteria reach – Via air by directsedimentation into the wound or theinstruments.• Highest conc. – within the circle of surgicalteam directly over the wound.• No of bacteria directly proportional to theincrease in activity and number of the team –max. at the time of induction, positioning andextubation/ Closure.
• Staphylococcus aureus carrier – 30-50% ofgeneral population.• Every person sheds ~55,000 skin scales/min. –10-20% contain live bacteria.• Increase in shedding:– Loose cotton scrub suits– Higher temperature & humidity.
Gloves• In a study of 1209 cases – 141 gloves werefound punctured.• 18,000 Staph aureus can pass a singlepuncture in 20min.• 3-5 min hand scrub with antiseptic soln. isessential.• Double gloves – additional security.• New cut resistant gloves.
Airborne bacteria• Air handling systems of OT.• Type of scrub suits worn.• Air bacterial count in ordinary OT varies from50 – 500 colony meter cube• “A Sterile air operating room” &Concept of “Rapid Unimpeded Down flow ofFiltered Air and Exhaust Ventilated WholeBody Suit” – Sir John Charnley
Microbiological facts:1. Airborne bacterial contamination is directlyrelated to number & activity of people in OR.2. Inversely related to the effectiveness ofpersonnel garment barrier & no. of airexchange / hour.3. Air borne bacteria are agglomerated oninanimate particles size from 2-10 microns.4. Almost always gram positive correspondingto skin flora.
Methods of cleaning air1. Laminar air flow – clean, filtered air withfrequent whole air exchange.2. Ultraviolet light system3. Vacuum body exhaust system4. Garment barrier.5. HEPA (High Efficacy Particle Air filter) –removing 99.9% particles larger than 0.3microns. (Bacteria - .5-10.5)
Laminar flow• Super-high air turn over (400-600) in a laminarflow room – “Air broom” action.• Flow – Horizontal or Vertical.• Conventional OR – 12-25 air exchanges eachhour – Federal standards.• “Unobstructed” – If not –positive pressure is generated• Doors kept closed.
• Air temperature – 21.1 to 24.4 C– Lower temperatures are preferred.• Humidity: 50%– Prevent static electricity and– Decrease perspiration– Decreased viability of bacteria
Garment Barrier• AORN recommends:– Pant suit or one piece suit with ankle closure &shoe covers.– All hair covered by cap or hood– Face mask – high microbial filtration efficacy.• Micro porous textile – disposable/reusable –use in gown & drape barrier systems.
• Standard cotton scrub suit or drapes –– pore size 100 microns– Sheds more bacteria“Cheese grater” effect.– “Bellows” action– Wet
• Microporous material is superior as:– Resistance to blood & water– Abrasion resistant– Lint free– Memory free– High degree of drapability.• e.g Polypropylenenonwoven gown.
Host defense mechanism• Skin test score• Serum albumin level• Age of the patient– Prediction regarding susceptibility to infection• Other factors– Diabetes, Old age, Obesity, Rh Arthritis,– Major implant surgery– AIDS
• Protein calorie malnutrition – most imp.factor.• Clean wound infection rate in– Diabetics – 10.5%– With obesity – 13.5%– With malnutrition 16.5%• Polytrauma patients.• These compromised situations - decisionregarding early operative intervention has toweigh against possibility of infection.
Organisms• 60% of SSI – Gram +ve bacteria esp. Staphaureus and epidermidis.• 20% - Gram –ve bacteria like E.Coli,Pseudomonas, Klebsiella etc.• Precise bacteriological diagnosis– 6 aerobic and anaerobic cultures.– Enriched media for at least 2 weeks.
• 90% of implant surgeries result fromintraoperative contamination.• 50% of these become clinically evident 3months after surgery• Many of these caused by low virulenceorganisms like Staph epidermidis and otheranaerobes.• Steady increase in G –ve bacteria – moredifficult to treat as is resistant Staph aureus.
• 2-8 million inoculums of Staph aureus injecteddevelop infection.• Only 100 organisms in presence of foreignbody.• Main reservoir – human body.• Nasal carriers – 30-50% of general population.• Glycocalyx biofilms:– Bacteria get adhered to implant surface.
Susceptibility of bone to infection• Limited soft tissue space• Blood supply favoring necrosis• Inadequate mechanism to reabsorb necroticbone• Increased duration of surgery
Role of prophylactic antibiotics• Tengve et al reported– 16.9% rate of infection with no antibiotics.– 1.8% with prophylactic antibiotics.• Antibiotics given before bacterial inoculation– Inhibit growth of bacteria• After inoculation– Prevent overt clinical signs of infection, butbacteria can always be isolated from the wound.
Pathophysiology• As a response to operative trauma– Maximum exudation occurs in the first 6 hrs and– Contamination occurs at the time of surgery• Antibiotic must be present in the circulation &into hematoma throughout the operation insufficient concentration – to kill thesebacteria.
Prophylactic antibiotic• Started just before surgery• Ideal conc. in serum during surgery should be4% of MIC in a healthy individual.8% in a compromised patient.• No extra advantage of continuing for 5 ormore days over limited therapy. (Stone et al)
Topical antibiotics• Willson et al 1991 – Topical triple antibioticsoln.- Neuromycin, polymyxin and bacitracin.• Bacitracin – allergic rxn so stopped.• Simple good wash with NS or RL is veryeffective.
Clinical presentation of postoperativeinfection• 3 types of presentation:1. Early – within 8 weeks2. Delayed – 8 weeks – 1 year.3. Late – after 1 year.• Early further 4 types (Mukhopadaya)i. Imminent within 48 hrsii. 3-9 days i.e. before suture removaliii. 10-21stday andiv. 3-8 weeks.
Classical presentation• Disproportionate pain• Fever >102 F• Wound – signs of local cellulitis• Mild to moderate serosanguineous discharge.Seen only when antibiotics and antiinflammatory are not given.
Common presentation• Severe pain• Fever not responding to high doses of drugs• Frank purulent discharge• Wound already partially opened up due to cutthrough sutures.
Late infection• Go home with apparently normal woundhealing• Return with chronic discharging sinus• Persistent tachycardia• Pain not presenting complaint.
Diagnosis of infection• Fever and Leukocytosis – not always helpful.• Thrombotic index• “Leukergy” – based on the phenomenon– WBCs agglomerate in the peripheral blood ofpatients with inflammatory disease.– Percentage of agglomerated cells correlate withthe severity of infection.– Rapid and inexpensive.
• Persistent elevation of ESR –– Suggests infection– Neither very sensitive nor specific.• ESR with CRP• Results better but still unreliable.• Bone scan – more accurate.
Treatment• Immediate action.• Discharging fluid to be sent for –– Gram staining,– Culture & sensitivity.• Broad spectrum antibiotic along withaminoglycoside started – no relief in 24 hrs –• Open and debride thoroughly.• Always better to debride than wait forantibiotics to act.
• Wound always closed by loose intermittentsutures or by secondary suturing later.• A well fixed implant can be left as such.• Loose implant – removal or refixation orExfixation.• Implants once infected needs removal• Well fixed implant left in place till fractureunites.
• Plate fixation – Early diagnosis and removal –extensive cortical necrosis.• Non union is not due to infection butinadequate fixation.
• Sir John Charnley 1982“Because of the tragic seriousness of postoperative infection, I regard it as our duty tocontinue in the future to study to eliminatepost operative infection by any means orcombination of means, whatever, I sayeliminate deliberately because I have not yetabandoned the hope that some way we’llachieve this target”