Surgical Wounds and Antimicrobial prophylaxis

Philip G. Murphy

Consultant in Medical Microbiology, AMNCH

Clinical Professor, TCD

philip.murphy@amnch.ie (ext 3919)

Humanity has three great enemies:

Fever, famine and war,

Of these by far the greatest,

By far the most terrible is fever.

William Osler

1849-1919

History

• 1862 Pasteur

• 1865 Lister

• 1866 Semmelweiss

• 1940’s Antibiotic era

• Today ?? Postantibiotic era <2 %

Public Health Importance of Public Health Importance of Surgical Site InfectionsSurgical Site Infections

• In U.S., >40 million inpatient surgical procedures each year; 2-5% complicated by surgical site infection

• SSIs second most common nosocomial infection (24% of all nosocomial infections)

• Prolong hospital stay by 7.4 days

• Cost $400-$2,600 per infection (TOTAL: $130-$845 million/year)

Source of SSI PathogensSource of SSI Pathogens

• Endogenous flora of the patient

• Operating theater environment

• Hospital personnel (MDs/RNs/staff)

• Seeding of the operative site from distant focus

of infection (prosthetic device, implants)

Pathogenesis

• Skin flora into wound margins / deep sites

• Surgical risk factors eg haematoma, ischaemia, prostheses

• Host factors, eg diabetes, steroid Rx

• Bacterial factors eg., innoculum, virulence eg GNB + anerobes

Rubour,(Redness) Dolour, (pain, tenderness) Tumour, (swelling)

DiagnosisDiagnosis

FeverCRP, ESR, WBC

SSI- Wound classifications

• Superficial• Deep• Organ/space

Merely a flesh wound

Wound healing - stages

Primary Healing – Occurring when a wound is closed within a few hours of its creation. Wound edges are surgically or mechanically approximated, and collagen metabolism provides long-term

strength. Delayed Primary Healing – Occurs when a poorly delineated wound is left open to protect against

wound infection. The open wound allows for the natural host defense to debride the wound before closure.

Secondary Healing – Occurs when an open full

thickness wound is allowed to close by wound contraction and epithelialization.

Healing of Partial-Thickness Wounds – Occurs

when a partial-thickness wound is closed primarily by epithelialization. This wound healing involves the superficial portion of the dermis. There is minimal collagen deposition, and an absence of wound contraction.

SSI Risk FactorsSSI Risk Factors

• Age• Obesity• Diabetes• Malnutrition• Prolonged preoperative

stay• Infection at remote site• Systemic steroid use• Immunotherapy• Nicotine use

• Hair removal/Shaving• Duration of surgery• Surgical technique• Haematoma• Necrosis• Foreign body• Presence of drains• Inappropriate use of

antimicrobial prophylaxis

SSI - Classification and RatesSSI - Classification and Rates• Clean

- no intrinsic bacterial flora <2 %

• Clean / contaminated - involving a viscus with bacterial flora 8%

• Contaminated - involves spillage of viscus content 15%

• Dirty - involves inflammation or viscus perforation

40%

<30 days post-op1 year orthopaedics

Bacterial aetiologyBacterial aetiologyCDC – NNIS dataCDC – NNIS data

Microbiology of SSIsMicrobiology of SSIs

Staphylococcusaureus

17%

Coagulase neg.staphylococci

12%

Escherichiacoli10%

Enterococcusspp.8%

Pseudomonasaeruginosa

8%

Staphylococcusaureus

20%

Coagulase neg.staphylococci

14%

Escherichiacoli8%

Enterococcusspp.12%

Pseudomonasaeruginosa

8%

1986-1989(N=16,727)

1990-1996(N=17,671)

BacteriologyBacteriology

• UK Survey:

Staphylococci 40-45 %

GNB 40-45 %

other aerobes 6 %

anaerobes 5 %

• Specific surgery types have different rates:

BacteriologyBacteriology

• Staphylococci and skin flora in bone and cardiac surgery

• GNB in biliary surgery

• Streptococci and anaerobes in gynae

• Colonic surgery:aerobic GNB 10 6-7 / G

Enterococci 10 5-6 / G

Bacteroides 10 9-11 /G

anaerobic cocci 10 10 / G

PREVENTION IS PRIMARY!

PREVENTION IS PRIMARY!

Protect patients…protect healthcare personnel…

promote quality healthcare!

Theatre environment

Theatre designTheatre design

• Min staff• 20-30 air changes/ hr• Plenum flow• Positive pressure• HEPA filtration• Asepsis: hand hygiene• Clothing• THINK HYGIENE

Prevention 1Prevention 1• Pre-op:

avoid antibiotics, minimise hospitalisation, treat remote infection, decolonise Staph, avoid/delay shaving, chlorhexidine bath, resolve obesity/malnutrition, control smoking or diabetes

• Intra-op:Skin prep, aseptic technique, filtered air, antibiotic wound

irrigation, isolate clean / dirty surgical fields - trays, reglove & new instruments from donor vein to CABG, minimise drains, separate drain wound minimise dead space haematomas and devitalised tissue

• Post-op:minimise catheters & IV lines, maintain oxygenation hydration & nutrition

Prevention 2Prevention 2

• Bowel preparation:

No irrigation, diets, or non- absorbable antibiotics

Theatre design & technique:

workflow zoning, air flow, CSSD, restricted staffing, aseptic technique etc.

Wound managementDressing - no touch technique,

Drainage – none or closed or vacuum drains if pus

Antibiotic prophylaxis - principles

• First dose immediately pre-op

• maximum of 3 doses or 24h period

• Rarely > 24h

• parenteral, PR

• No non-absorbables

• Rarely required in clean or clean/contaminated

Perioperative Antibiotics- Perioperative Antibiotics- ProphylacticProphylactic

• Prophylactic antibiotics should exist at time of contamination. Clean- contaminated and Contaminated showed reduction

• In clean only when Foreign Body is inserted• Preoperative, close to cutting time, long half- life, selected

against specific pathogens, 4-6 hours later, and for 2 postoperative doses

• Colon surgery: Oral antibiotics, poorly absorbed; neomycin- erythromycin along with mechanical preparation, and IV systemic

• Dirty: fascial closure, wet-to-dry dressing and delayed primary closure in 4-5 days

Importance of Timing of Surgical Importance of Timing of Surgical Antimicrobial Prophylaxis (AP)Antimicrobial Prophylaxis (AP)

• Prospective study of 2,847 elective clean and clean-contaminated procedures

• Early AP (2-24 hrs before incision): 3.8% Postop AP (3-24 hrs after incision): 3.3% Periop AP (< 3 hrs after incision): 1.4% Preop AP (<2 hrs before incision): 0.6%

Classen, 1992 (NEJM 326:281-286)

Antibiotic prophylaxis dynamics

Time of administration

Bacterial load

Prophylaxis - specificIndication Antibiotic Durationabove knee amputation benzyl penicillin 1 dose

Cholecystectomy cefuroxime 1 dose

Appendicectomy metronidazole 3 doses

Colectomy Cefuroxime + 3 doses

metronidazole

vaginal hysterectomy as above as above

or augmentin

Prosthetic hip replacement cefuroxime 2 doses

Prosthetic heart valve cefuroxime or fluclox tid <48h

Vascular prosthesis as above as above

Supplemental Perioperative OSupplemental Perioperative O22

• DESIGN: Randomized controlled trial, double blind

• POPULATION: Colorectal surgery (N=500)• INTERVENTION: 30% vs 80% inspired

oxygen during and up to hours after surgery

• RESULTS: SSI incidence 5.2% (80% O2) vs 11.2% (30% O2), p=0.01

Greif, R, et al , NEJM, 2000

Seropian, 1971Method of hair removal

Razor = 5.6% SSI ratesDepilatory = 0.6% SSI ratesNo hair removal = 0.6% SSI rates

Timing of hair removalShaving immediately before = 3.1% SSI ratesShaving 24 hours before = 7.1% SSI ratesShaving >24 hours before = 20% SSI rates

Pre-operative Shaving/Hair Removal

Surgical AttireSurgical Attire

• Scrub suits

• Cap/hoods

• Shoe covers

• Masks

• Gloves

• Gowns

Instruments and infection controlInstruments and infection controlCSSDCSSD

Parameters for Operating Room Parameters for Operating Room VentilationVentilation

• Temperature:

68o-73oF, depending on normal ambient temp

• Relative humidity:

30%-60%

• Air movement:

from “clean to less clean” areas

• Air changes:

>15 total per hour, (20 routine, 30 orthopaedic)

>3 outdoor air per hour

Surgical TechniqueSurgical Technique

• Removing devitalized tissue

• Maintaining effective hemostasis

• Gently handling tissues

• Eradicating dead space

• Avoiding inadvertent entries into a viscus

• Using drains and suture material appropriately

Treatment

• Most infection are superficial – no antibiotics• If complicated - open, drain, debride, micro & Abx• Topical Vs systemic• Saline Vs disinfectant Vs antibiotic• Target organisms Vs culture• empirical Vs culture targeted• one drug Vs two• Remove all prostheses / implants• pus collection drainage

SurveillanceSurveillance

• Infection Control Team

• Link nurses

• Databases

• Early discharge, day surgery

• Post discharge

Reading referenceReading reference

http://www.cdc.gov/ncidod/dhqp/pdf/guidelines/SSI.pdf

The CDC NNIS 1999 guidance document is the comprehensive reference,(23 pages) :