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

CLASSIFICATIONPre operative infections: before a

surgical procedure - Accidents- Appendicitis- Boils- Carbuncle- Pyomyositis

Operative infections• Happen during a surgical procedure• Due to-contamination of the site -poor tissue handling

Postoperative infections• Occur after a surgical procedure• Contamination is from the patient’s sourcee.g - Surgical wound infections - Urinary & respiratory tract infection

PATHOGENESIS Elements or factors include:- An infectious agent- A susceptible host- Favorable external factors/ environment

Infectious agents1- Aerobic bacteria- Staphylococcus

aureus- Streptococci- Klebsiella- E. coli

2- Anaerobic bacteria- Bacteroides- Peptostreptococci- Clostridia

Infectious agents3- 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 elevated• Gram stain , culture & sensitivity• Blood culture: bacterermia• Biopsy: Histologic• X-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 pus• Contains necrotic tissue & suppurationEtiology-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

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

CellulitisNon-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 bodies• Systemic - fever, chills, malaise• Pain, tenderness, edema, erythema with

poorly defined margins

cellulitis

Cellulitis

Investigation• CBC, blood cultures• Culture and Gram stain• Plain radiographs- R/o osteomyelitisClellulitis 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 & trunk• Associated 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 fasciitisRapidly 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

EtiologyPolymicrobial - 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 resuscitation• Multiple surgical debridement: remove

all necrotic tissue, copious irrigation• IV 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