SURGICAL INFECTIONS

Begashaw M (MD)

Surgical infection

Defined as an infection related to or complicating a surgical therapy and requiring surgical management

Related to surgical therapy but may not require surgery

- UTI after catheterization- Pulmonary CXN after intubation- Tracheotomy site infection- Post-operative wound infection

CLASSIFICATION

Pre operative infections: before a surgical procedure

- Accidents

- Appendicitis

- Boils

- Carbuncle

- Pyomyositis

Operative infections

Happen during a surgical procedureDue to -contamination of the site

-poor tissue handling

Postoperative infections

Occur after a surgical procedureContamination is from the patient’s

source

e.g

- Surgical wound infections

- Urinary & respiratory tract infection

PATHOGENESIS

Elements or factors include:

- An infectious agent

- A susceptible host

- Favorable external factors/ environment

Infectious agents

1- Aerobic bacteria

- Staphylococcus aureus

- Streptococci

- Klebsiella

- E. coli

2- Anaerobic bacteria

- Bacteroides

- Peptostreptococci

- Clostridia

Infectious agents

3- Fungi

- Histoplasma

- Candida

- Nocardia and actinomycetes

4- Parasites

- Entameba hystolytica-amebic liver abscess

- Echinococcus - hydatid cyst

Host Susceptibility

Reduced immunity/host defense

-Diabetes mellitus

-TB

-AIDS

Local and external factors

Local factors

- Poor vascularization

- Poor perfusion of blood and oxygen

- Dead tissue

- Foreign bodies

- Closure under tension External factors-break in the sterility

technique

Clinical manifestation

Hotness, redness, edema/swelling, pain & loss of function

Non-Specific symptoms- Fever, chills, tachycardia

Constitutional symptoms - Fatigue, low-grade fever

Investigations

WBC count: usually elevatedGram stain , culture & sensitivityBlood culture: bacterermiaBiopsy: HistologicX-ray and ultrasound

Post-Operative Wound Infection

Is contamination of a surgical wound during or after a surgical procedure

Is usually confined superficial Below the fascia - deep infection

Types of Surgical Site Infections

Source of infection

80% cases - patient (Endogenous)

-skin ,transected viscus. In about 20% cases - Exogenous

-environment

-operating staff

-unsterile surgical equipment

Clinical Findings

On the 5th-7th postoperative day

- Fever

- Wound pain

- Wound edema and induration

- Local hotness and tenderness

- Wound/stitch abscess

- Serous discharge

- Crepitation

Wound infection

Management

- Remove stitches to allow drainage

- Local wound care

- Antibiotics-if systemic manifestations/cellulitis

Prevention

Shorten preop. Hospitalization Loose weight Treatment of remote infection Shorten operative time Restore host defense Decrease endogenous bacterial cont. Good surgical technique Proper asepsis and antisepsis Chemoprophylaxis

Abscess

Localized collection of pusContains necrotic tissue & suppuration

Etiology

-Pyogenic organisms - staphylococci

Abscess

Clinical features

- Superficial (Hot, pain, edema, redness and loss of function)

- Fluctuation

- Discharge & sinus

- Systemic - fever, sweating, tachycardia

Treatment

- Drainage by incision

- Debridement & curettage

- Delayed primary or secondary closure

- Antibiotics - systemic symptoms or signs of spread occur-cloxacillin

Abcsess drainage

Abscess drainage

Erysipelas

_ Acute skin infection that is more superficial than cellulitis

_ Etiology

- Group A Streptococcus (GABHS)

_Clinical Features

Intense erythema, induration, & sharply demarcated borders

_Treatment - penicillin or first generation cephalosporin - cephalexin

Eryspelas

Cellulitis

Non-suppurative infection of skin and subcutaneous tissues

Usually involves the extremities Identifiable portal of entry Etiology: skin flora

- Beta hemolytic streptococci

- Staphylococci

- Clostridium perfringens

Clinical Features

Source of infection

-trauma, recent surgery

-diabetes - cracked skin

-foreign bodiesSystemic - fever, chills, malaisePain, tenderness, edema, erythema with

poorly defined margins

cellulitis

Cellulitis

Investigation

CBC, blood culturesCulture and Gram stainPlain radiographs- R/o osteomyelitis Cellulitis Vs Eryspela

-Cellulitis: indistinct border

-Erysipela: sharp boarder

Management

- Rest

- Elevation/immobilize

- Hot, wet pack

- High dose broad spectrum antibiotics IV

_Cloxacillin 500 mg QID/cephalexin

Pyomyositis

Acute bacterial infection of skeletal muscles with accumulation of pus in the intramuscular area

Occurs in the lower limbs & trunkAssociated factors-Poor nutrition

-immune deficiency

-hot climate

-intense muscle activity

Etiology

-Staphylococcus aureus - common

-Streptococci

Clinical Features

Sub-acute onset

• Localized muscle pain & swelling• Tenderness

• Induration, erythema, heat

• Muscle necrosis

• Fever

Pyomyositis

Treatment

• Intravenous antibiotics- cloxacillin

• Surgical drainage

• Excision -necrotic muscle

• Supportive care-analgesics

Necrotizing fasciitis

Rapidly spreading, very painful infection of the deep fascia with necrosis of tissues

Some bacteria create gas that can be felt as crepitus

Infection spreads rapidly along deep fascial plane and is limb and life threatening

Etiology

Polymicrobial

- Streptococci- hemolytic

- Staphylococci

- Gram negative bacteria

- Anaerobes

- Clostridia

Clinical Features

Pain out of proportion Erythema, edema, tenderness, ± crepitus ±fever Infection spreads very rapidly Rapidly become very sick/toxic Skin turns dusky blue and black (secondary to

thrombosis & necrosis) Induration, formation of bullae Cutaneous gangrene, subcutaneous emphysema

Necrotizing fascitis

Treatment

Rigorous resuscitationMultiple surgical debridement: remove all

necrotic tissue, copious irrigationIV antibiotics-Ceftriaxone +Metronidazole

Gas Gangrene

Characterized by muscle necrosis and systemic toxicity

Follows - Trauma

- Surgery

- Foreign bodies

- Vascular insufficiency

Etiology

-Clostridium perfringens -80% of cases

- polymicrobial infection

Clinical features

- Sudden and persistent severe pain at wound site

- Localized tense edema, pallor , tenderness

- Gas noted on palpation or radiograph

- brownish discoloration of skin and hemorrhagic bullae

- Dirty brown discharge with offensive, sweetish odor

- Systemic - fever, tachycardia,hypotension

Gas on soft tissue

Management

Surgery - important

-Extensive, wide excision

-Amputation

-Antibiotic

-Supportive

- Intravenous infusions

- Blood transfusions

- Close monitoring

TETANUS

Cl. Tetani, produce neurotoxin Penetrating wound ( rusty nail, thorn )

Usually wound healed when symptoms appear Incubation period: 7-10 days Trismus - first symptom, stiffness in neck & back Anxious look with mouth drawn up ( risus sardonicus)

Respiration & swallowing progressively difficult Reflex convulsions along with tonic spasm Death by exhaustion, aspiration or asphyxiation

TETANUS

Treatment: wound debridement, penicillin Muscle relaxants, ventilatory support Nutritional support

Prophylaxis: wound care, antibiotics

Human TIG in high risk ( un-immunized ) Commence active immunization ( T toxoid)

Previously immunized- booster >10 years needs a booster dose booster <10 years- no treatment in low risk wounds