Wound Infection(1)

8/3/2019 Wound Infection(1)

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Wound Infection

Definitions of SSI

Superficial incisional SSI: Infection involves only skin and

subcutaneous tissue of incision.

Deep incisional SSI: Infection involves deep tissues, such asfascial and muscle layers also superficial and deep incisionsites and organ/space SSI draining through incision.

Organ/space SSI: Infection involves any part of theanatomy in organs and spaces other than the incision,which was opened or manipulated during operation.

Surgical site infections (SSI)


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Types of SSI


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Superficial incisional SSI Occurs within 30 days after the operation

Involves only the skin or subcutaneous tissue

At least 1 of the following: Purulent drainage is present. Organisms are isolated from fluid/tissue of the

superficial incision.

At least 1 sign of inflammation (eg, pain or tenderness,induration, erythema, local warmth of the wound) ispresent.

The wound is deliberately opened by the surgeon. The surgeon or attending physician declares the woundinfected


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Deep incisional SSI

Occurs within 30 days of the operation or within 1year if an implant is present

Involves deep soft tissues of the incision

At least 1 of the following: Purulent drainage is present from the deep incision but

without organ/space involvement.

Fascial dehiscence or fascia is deliberately separatedby the surgeon because of signs of inflammation.

A deep abscess is identified by direct examination or

during reoperation, by histopathology, or by radiologicexamination.

The surgeon or attending physician declares that adeep incisional infection is present


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Organ/space SSI

Organ/space SSI Occurs within 30 days of the operation or within 1 year if an

implant is present

Involves anatomical structures not opened or manipulatedduring the operation

At least 1 of the following: Purulent drainage is present from a drain placed by a stab

wound into the organ/space.

Organisms are isolated from the organ/space by asepticculturing technique.

An abscess in the organ/space is identified by directexamination, during reoperation, or by histopathologic orradiologic examination.

A diagnosis of organ/space SSI is made by the surgeon orattending physician


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Causes

Microbiology Most SSIs are contaminated by the patient's

own endogenous flora

The usual pathogens on skin and mucosal

surfaces are gram-positive cocci gastrointestinal surgery intrinsic bowel flora,

gram-negative bacilli, and gram-positivemicrobes, including enterococci and anaerobicorganisms

Gram-positive organisms, particularlystaphylococci and streptococci, account formost exogenous flora involved in SSIs


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Pathogens causing Wound

InfectionsPathogen Frequency (%)

Staphylococcus aureus 20

Coagulase-negative staphylococci 14

Enterococci 12Escherichia coli 8

Pseudomonas aeruginosa 8

Enterobacterspecies 7

Proteus mirabilis 3

Klebsiella pneumoniae 3Other streptococci 3

Candida albicans 3

Group D streptococci 2

Other gram-positive aerobes 2

Bacteroides fragilis 2


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Host factors Systemic factors: age, malnutrition, hypovolemia, poor

tissue perfusion, obesity, diabetes, steroids, and otherimmunosuppressants.

Wound characteristics: nonviable tissue in wound;hematoma; foreign material, including drains and sutures;dead space; poor skin preparation, including shaving; andpreexistent sepsis (local or distant).

Operative characteristics: poor surgical technique; lengthyoperation (>2 h); intraoperative contamination, including

infected theater staff and instruments and inadequatetheater ventilation; prolonged preoperative stay in thehospital; and hypothermia


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Risk Factors for Development of Surgical Site Infections

Patient factors

Older age

Immunosuppression

Obesity

Diabetes mellitus

Chronic inflammatory process

Malnutrition, Anemia

Peripheral vascular disease

Radiation

Carrier state (e.g., chronic Staphylococcus carriage)

Local factors

Poor skin preparation

Contamination of instruments

Inadequate antibiotic prophylaxis

Prolonged procedure

Local tissue necrosis

Hypoxia, hypothermia

Microbial factors

Prolonged hospitalization (leading to nosocomial organisms)

Toxin secretion

Resistance to clearance (e.g., capsule formation)


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WoundC

ontaminationClassification Description Risk (%)

Clean

(Class I)

Uninfected operative wound

No acute inflammation

Closed primarily

Respiratory, gastrointestinal, biliary, and urinary tracts not entered

No break in aseptic techniqueClosed drainage used if necessary


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The National Nosocomial Infection Surveillance (NNIS)

risk index

risk index

(1) American Society of Anesthesiologists

(ASA) Physical Status score >2

(2) class III/IV wound

(3) duration of operation greater than the

75th percentile for that particularprocedure


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American Society of

Anesthesiologists (ASA)

Classification of Physical Status

ASAScore Characteristics

1 Normal healthypatient

2 Patient with mild systemic disease

3Patient with a severe systemic disease that limits

activity but is not incapacitating

4 Patient with an incapacitating systemic disease that isa constant threat to life

5Moribund patient not expected to survive 24 hours with

or without operation


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Predictive Percentage of SSI

Occurrence byRisk Index

At Risk Index Predictive Percentage ofSSI

0 1.5

1 2.9

26

.8

3 13.0


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Time Relations

Early (24-48h); streptococci and

clostridia, Immunosuppression

Usual; (5-10d); others

Delayed (2-4w); infection of hematoma or

seroma


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Lab

Staining methods: Gram stain simple, quick.

Culture techniques: both aerobic and anaerobic. Fungalcultures. Then sensitivity testing

Newer techniques Tests for antigens from the organism through enzyme-

linked immunoassay (ELISA) or radioimmunoassay

Detection of antibody response in the host sera

Detection ofRNA or DNA sequences orprotein from theinfective organism

Polymerase chain reaction (PCR) to detect small amountsof microbe DNA.


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RECOMMENDATIONS FROM THE HOSPITAL INFECTION CONTROL

PRACTICESADVISORY COMMITTEE FOR THE PREVENTION OF

SURGICALSITE INFECTIONS

Do not operate on patients with active infections

Do not shave patient in advance

Control glucose in diabetic patients

Stop tobacco use in patient

Have patient shower with antiseptic soap

Prepare skin with appropriate agent

Surgeon's nails should be short

Surgeons scrub hands

Exclude infected surgeons

Give prophylactic antibiotics when indicated

Maintain prophylactic antibiotic levels during operation

Keep O.R. doors closed


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RECOMMENDATIONS FROM THE HOSPITAL INFECTION CONTROL

PRACTICESADVISORY COMMITTEE FOR THE PREVENTION OF

SURGICALSITE INFECTIONS

Use sterile instruments Avoid flash sterilization

Wear a mask

Cover all hair

Wear sterile gloves

Use gowns and drapes that resist fluid penetration

Gentle tissue handling

Closed suction drains (when used)

Delayed primary closure for heavily contaminatedwounds

Sterile dressing for24- 48 hr

SSI surveillance with feedback to surgeons


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Recommendations for

Prophylactic Antibiotics

antibiotics had to be in the circulatory

system at a high enough dose at the time

of incision to be effective clean-contaminated and contaminated

wounds

clean procedures in which prosthetic

devices is implanted


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Recommendations for

Prophylactic Antibiotics The antibiotic should be administeredpreoperatively as close to the time of theincision as is practical before induction of

anesthesia in most situations.

The antibiotic should have activity against thepathogens likely to be encountered.

Postoperative administration ofpreventive

systemic antibiotics beyond 24

hours has notbeen demonstrated to reduce the risk of SSIs.


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Recommendations for

Prophylactic Antibiotics

good tissue penetration to reach wound

involved.

cost effectiveness.

minimal disturbance to intrinsic body flora


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Antibiotics as Indicated by Probable Infective

Microorganism

Operation ExpectedP

athogens RecommendedA

ntibioticOrthopedic surgery (including

prosthesis insertion), cardiac

surgery, neurosurgery, breast

surgery, noncardiac thoracic

procedures

S aureus, coagulase-negative

staphylococciCefazolin 1-2 g

Appendectomy, biliaryprocedures Gram-negative bacilli and anaerobes Cefazolin 1-2 g

Colorectal surgery Gram-negative bacilli and anaerobes Cefoxitin 1-2 g

Gastroduodenal surgeryGram-negative bacilli and

streptococciCefazolin 1-2 g

Vascular surgeryS aureus, Staphylococcus

epidermidis, gram-negativebacilli

Cefazolin 1-2 g

Head and neck surgeryS aureus, streptococci, anaerobes

and streptococcipresent in an

oropharyngeal approach

Cefazolin 1-2 g

Obstetric and gynecological

procedures

Gram-negative bacilli, enterococci,

anaerobes, group B streptococciCefazolin 1-2 g

Urologyprocedures Gram-negative bacilli Cefazolin 1-2 g


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Special situations

Elective colon surgery: Mechanical cleansing andantibiotics

Dietary restrictions.

Whole gut lavage ; 10% mannitol solution, Fleet's phospho-soda, orpolyethylene glycol, usually is performed on theday of surgical intervention.

Enteral antibiotic regimes with oral neomycin anderythromycin being the most popular combination,metronidazole and tetracycline.

Catheter- related infections: Morbidity and mortality (up to20% in patients with catheter-related bloodstreaminfections).


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Newer concepts in the prevention

of SSIs

close regulation of blood sugar in patients withdiabetes,.

body temperature; failure to maintain

intraoperative core body temperature within 1-1.5C of normal increases the SSI rate by afactor of2.

oxygenation. Maintaining or increasing oxygendelivery to the wound by increasing the inspired

oxygen concentration administered to the patientperioperatively has also been shown to reducethe incidence of SSIs.


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Treatment

incision and drainage without the addition

of antibiotics.

Antibiotic therapy is reserved forpatientsin whom evidence of severe cellulitis is

present, or who manifest concurrent

sepsis syndrome.

The open wound often is allowed to heal

by secondary intention


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Further Care

Inpatient Care:

increased hospital stay due to SSI 7-10 days

increasing costs by20%

Occasionally, wound debridement and subsequent packingand frequent dressing is necessary to allow healing bysecondary intention.

Outpatient Care:

Most patients with wound infections are managed in thecommunity. Management usually takes the form of dressingchanges, which usually is by secondary intention.

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Wound Infection(1)