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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
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