Download 28. surgical-infection

Surgical Infections,
Antibiotics & Asepsis
Dr.Mohd AlAkeely
Associate Professor & Consultant
General Surgery
Objectives:
1. To be able to diagnosed, investigate and manage common
community acquired infections.
2. To have a basic understanding of prevention and
management of hospital acquired infection (noso-comial).
3. To have a basic understanding of the methods of Asepsis
and its implications.
4. To have a guideline in the use of antibiotics for both therapy
and prophylaxic and the awareness of main side effects of
commonly used antibiotics.
References:
. Sabiston Textbook of Surgery
18th Edition Pages 299- 327
. Schwartz Principles of Surgery
8th Edition Pages 109- 127
Baily & love 24th edition
Introduction
Definition;
it is the infection that requires surgical treatment
0R a complication of a surgical treatment.
It accounts for one-third of surgical patients.
Important complication of any invasive procedure.
For an infection to develop, four factors:
1- adequate dose of the micro-organism.
2- virulence of the organism.
3- susceptible host.
4- suitable environment.
The virulence
Is the ability of bacteria to produce toxins or
resist phagocytosis (encapsulated organisms).
There are two types of toxins:
- exotoxins.
- endotoxins.
Endotoxins
• Lipopolysaccharides
• Part of gram –ve bacterial wall [ released after destruction of
bacteria].
• Do not have specific effects for each type of
bacteria
• It causes gram –ve shock (septicemea)
Exotoxins
* Soluble proteins
* Released from intact bacteria (gram +ve & -ve)
* Have specific effects for each type of bacteria
* Their effects are local and remote from the site
of release
Pathogenic potential is exalated by;
. genetic mutation
( e.g. β-lactamase of staph.aureus).
. Synergesty
Host resistance:
• Intact skin & mucous membrane.
• Good inflammatory response.
• Intact acquired immunity.
Phagocytosis and intraleucytic microbicidal
system is Affected by:

Poor blood perfusion

low oxygenatation

Hypothermia
These are called “the lethal triad’
Diagnosis of infection
Clinical features:
* Local features of inflammation (redness,hotness,pain,odema
and loss of function) which may not be all present.
* Systemic symptoms.
Investigations :
* CBC, ESR, CRP.
* Sample for gram stain & culture.
* Others.eg; serology & radiology.
Principles of treatment
• Debridement of wounds (necrotic tissue).
• Drainage of pus.
• Removal of the source and foreign bodies.
eg:
appendicectomy and cholecystectomy
• Supportive measures.
Surgical infection
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Cellulitis
Erysipelas
Lymphangitis
Boil (Furuncle)
Carbuncle
Hidradenitis suppurativa
Necrotizing fasciiti
Gas gangrene & tetanus
Pseudo memranous colitis
Common surgical infections
1- cellulitis:
.
•
•
•
Spreading infection of skin & subcutaneous tissue.
very common.
Caused by streptococcus (mainly ) & staph.
The area affected becomes red, hot, painful indurated and
tender.
Treatment:
 Penicilline
 (or erythromycin in sensitive patients).
 Rest & elevation of the affected limb.
 Hospital admission in severe cases.
Erysipelas.
. Superficial spreading skin infection
. Area of redness, sharply defined and irregular border
. Follows minor skin injuries
. Organism-Strep pyogenes
. Sensitive to Penicillin & Erythromycin
2- lymphangitis:
Inflammation of lymphatic pathway caused by
hemolytic streptococci
(usually secondary to cellulitis).
* Appears as red streaks on extremities.
* Treatment: antibiotics, rest and elevation.
3- Necrotizing fascitis:
• Necrosis of subcutaneous tissue underlying the skin.
• usually Polymicrobial infection.
• Common sites are:
abdominal wall, perineum and limbs.
• Usually follows abdominal surgery or trauma.
• Immune compromised [e.g.Diabetics and IV drug addicts] are
more susceptible .
Cont.
• Starts as cellulitis with early systemic toxicity.
But;
• Characterized by non-blanching erythema, with blisters and frank
necrosis of the skin.
• No definitive margins ( usually requires multiple debridements ).
• Extensive surgical debridement of the affected
area, in combination with high dose brod
spectrum is the appropriate Rx till C/S result.
4- gas gangrene:
Caused by cl. Perfringens (mainly) or cl. Septicum
• Commonly enter the body through wounds
contaminated with soil.
• Produce exotoxins.
• It is characterized by progressive rapidly
spreading edema.
Cont.
• Rapid myonecrosis it results in swelling,
seropurulent discharge, crepitus in
subcutaneous tissues, gas production and foul
smelling wounds.
• Other findings: ill looking patient, profound
toxemia, tachycardia and in X-ray appearance
of gas under skin and in muscles.
• Non clostredial gas gangrene can be caused by
gas forming anaerobic bacteria as in diabetic
foot which is usually multi microbial infection.
Treatment:
• Wound debridement, drainage and exposure.
• Antibiotics
(penicillins, clindamycin or metronidazole).
*Antibiotics are not effective without
aggressive debridement.
Cont Rx.
• Putting the patient in a hyperbaric oxygen
chamber may help (anerobic infection).
• Amputation may be required.
5- Tetanus:
• Caused by cl. tetani as complication of wound contamination.
• Usually the wound is healed when the symptoms start to
appear.
• Incubation period one to three weeks.
* Cl. tetani produces a neurotoxin that
stimulates the nerves in spinal cord that leads to muscle
spasm.
Cont.
• The first manifestations include trismus (lockjaw), neck
and back stiffness.
• Other manifestations include risus sardonicus
(an anxious look with mouth drawn up), progressive
dysphasia and difficult respiration and reflex
convulsions along with intense tonic
contractions of body muscles.
Cont.
• May result in death due to exhaustion,
aspiration or asphyxia.
Treatment & prophylaxis
•
Rx include wound debridement, penicillin,
muscle relaxants, ventilation and nutrition in
Intensive care unit.
Prophylaxis:
• Wound care & antibiotics.
• Vaccination by tetanus immunoglobulin in
high risk pts ( passive immunization ).
• Commence active immunization (T toxoid).
Cont.
• In previously immunized pt, if the booster
was:
• > 5 years, the pt needs another booster.
• < 5 years, no treatment.
PSEUDOMEMBRANOUS COLITIS
• Cl. Difficile
Overtakes normal flora in patients on antibiotics
Watery diarrhea, lower abdominal pain, fever
Sigmoidoscopy: membrane of exudates (pseudomembranes)
Stool- culture and toxin assay
Treatment :
Stop offending antibiotic
oral vancomycin/ metronidazole , rehydration, Isolate
patient.
Staphylococci
• Normal flora of the skin.
• The most common cause of surgical site infection
in surgical practice.
• Can cause endocarditis, Abscesses, furuncle (boil), carbuncles.
* Antibiotics effective against staph:
penicillin, cephalospoin and vancomycin
(MRSA).
Abscess :
• localized pus collection
• Treated by drainage & antibiotics.
Furuncle :
• Inflammation of hair follicles or sweat glands treated by
drainage & antibiotics.
Carbuncle : a large extension of furuncle.
• Common in diabetics, usually on the back and the neck,
treated by drainage & antibiotics.
Furunculoisis
paronychia
Pseudomonas
• Aerobic opportunistic bacteria that cause skin
infections, but also can cause lethal infections.
• It enter the body through minor skin. abrasions,
ventilator tubes, urinary catheter, I.V. lines etc…
• Treatment :
• aminoglycosides, piperacillin, ceftazidime.
Intra - abdominal abscess
• Important complication of G.I. & biliary
surgery.
• Clinical feature : abdominal pain tenderness
fever & leukocytosis.
• Investigation : X-ray, ultrasound, CT (the
most useful ).
• Treatment :drainage (surgical versus radiological ) &
broad antibiotics.
Hydradenitis suppurativa
. Infection of apocrine sweat glands
. axilla, groin, perineum, any skin fold
:TREATMEANT
. Single abscess treated by I&D
. Doxycycline 100mg BID
. Excision with STSG (15%)
Classification of wounds
1- Clean wound: surgery done through clean
tissue plains, no need for prophylaxis except for
high risk group.
Ex: thyroid, breast, hernia surgeries.
2-Clean/contaminated : surgery with suspesion of
infection.
Ex: cholecystectomy, urinary tract
surgery, etc…(entering body
cavities) prophylaxis is advisable.
Cont .
3- Contaminated :
surgery where microorganism are definitely
present.
ex: bowel surgery.
Therapeutic antibiotics is advisable.
4- Dirty :
surgery through well established infection
ex: abscess surgery.
the use of antibiotic is considered to
be of therapeutic nature.
Pressure sore
Surgical site infections (SSI)
. 38% of all surgical infections
. Infection within 30 days of operation
. Infection within 1 year if prosthetic device used.
Surgical site infection (SSI)
Classification:
Superficial SSI: skin & subcutaneous plane (47%)
Deep SSI: subfascial and muscle plane (23%)
Organ/ space SSI: intra-abdominal, other spaces (30%)
Staph. aureus- most common organism
E coli, Entercoccus , B fragilis
Surgical site infection (SSI)
Risk factors
. age
. malnutrition
. obesity
. Immune compromised
. poor surgical technique
. prolonged surgery
. preoperative shaving
. type of surgery
Surgical site infection (SSI)
• Diagnosis:
Sup.SSI- erythema, oedema, discharge and pain
RX: antibiotics & remove clips and drainage of pus (ClS).
Deep infections- no local signs, fever, pain, hypotension.
need investigations.
Treatment: surgical / radiological intervention.
Prevention of SSI
Pre-op: Treat pre-existing infection
Improve general nutrition
Shorter hospital stay
Pre-op. shower
Hair removal -shaving vs clipping
Intra-operative: Antiseptic technique
Good surgical technique
Normothermia
Post-operative:
Wound dressing in 48-72 hours
Early drain removal
Blood sugar control
ANTIBIOTICS
Chemotherapeutic agents directed towards micro-organisms.
They are either synthetic or semi-synthetic.
Penicillin has a wide safety margin, Inhibits cell-wall synthesis.
Hyper sensitivity
event. is the main side effect but luckily it is a rare
Therefore skin sensitivity test is a must before intravenous
therapy.
Gentamycine:
 Is the main aminoglycoside.
 It inhibits ribosome synthesis.
 Effective in Gram-ve bacteria.
eg:
psudomonas and E.coli.
side effects includes ;
ototoxicity and nephrotoxicity.
It has a narrow safety margin.
Tetracycline
 Is a wide spectrum bacteriostatic antibiotic
(gram+ve & gram-ve ).
 It alters the ribosome synthesis in bacteria.
 Main side effects includes:
- teeth discolouration
- risk of super infection
Amphotericin B

is an anti fungal which acts by impairing
DNA synthesis.
 It is a hepatotoxic and nephrotoxic in
high doses like gentamycine.
(narrow safety margine )
 This antibiotic should always be given with
frequent pre and post dose serum level
assessment.
Prophylactic antibiotic
Antibiotic which is given to patients bfeore surgery or
invasive procedure in order to prevent infection.
A high serum level of the antibiotic is essential just before
starting the procedure.
It is usually given intravenously or one hour intramuscularely
before the surgery. Antibiotic selection depends on
common bacteria in the operative site.
It is usually given in clean contaminated and contaminated
procedures.
Asepsis
- sterilization
• Wet heat in an autoclave at 121° c for 20 minutes, or at a higher
temperature for a shorter time (HTST) to provide an equivalent
exposure.
• Dry heat in a hot-air oven at 160° c for one hour.
• Irradiation under strictly controlled conditions (used predominantly
in industry).
• Special sterilizing chemicals, liquids or gases, such as formaldehyde,
glutaradehyde or ethylene oxide, under strictly controlled
conditions.
- disinfection
- Antisepses
Thank you !!
Now an example of exam questions:
Example of exam. MCQ
A 30 years old house-maid has a puncture wound in her right
hand 5 days ago, now she is presenting with painful,red ,hot
and swollen hand.PE revealed tenderness and the redness in
the hand is flat with the skin . What is the most likely
diagnosis?
a. Carbuncle.
b. Cellulitis.
c. Lymphangitis.
d. Erysipelas.
Example of exam. MCQ
A 30 years old house-maid has a puncture wound in her right
hand 5 days ago, now she is presenting with painful , red ,hot
and swollen hand.PE revealed tenderness and the redness in
the hand is flat with the skin. What is the most likely
diagnosis?
a. Curbuncle.
b. Cellulitis.
c. Lymphangitis.
d. Erysipelas.
MCQ Example :
A 25 years old male patient admitted via emergency
room complaining of fever, lower abdominal pain
and diarrhoea.He had appendectomy 7 days ago.
His s.site is clean. What is the most likely Dx ?
a.
b.
c.
d.
Gastro- enteritis.
Urinary tract infection.
Pelvic collection (abscess).
Diverticulitis.
MCQ Example :
A 25 years old male patient admitted via emergency
room complaining of fever, lower abdominal pain
and diarrhoea.He had appendectomy 7 days ago.
His s.site is clean. What is the most likely Dx ?
a.
b.
c.
d.
Gastro- enteritis.
Urinary tract infection.
Pelvic collection (abscess).
Diverticulitis.