For FCPS & MS entrance exam.

1. SURGICAL INFECTION
DR.TANVIR AHMED

2. ESTIMATED QUESTIONS
FCPS Paper 3 : 4 -5 Q ( b & l page 42 to 56)
FCPS Paper 2: Pharmacology : b & l page 56 : 1 to 2 Q
Residency : 2-3 Q

3. Surgical infection: Infection occurs during OT, Post
operative period or hospital stay.
A.Non specific:
1.Wound abscess
2.Cellulitis & lymphangitis
3.Bacteraemia & septicemia
CLASSIFICATION
B.Specific:
1.Tetanus
2.Gas gangrene
3.Necrotising fascitis

4. Common bacteria causing surgical infection
• Streptococci
• Staphylococci
• Clostridia
• Bacteroids
• Aerobic gram(-) bacilli: E.coli, klebsiella, proteus

5. Important for SBA:
• Strep. Pyogens: cellulitis
• Strep. Faecalis & peptostreptococci: wound infection after large
bowel surgery
• Staph.aureus: Exogenous suppuration in wounds and implanted
prosthesis, wound abscess
• Staph. Epidermidis: major threat in prosthetic (vascular &
orthopaedic)surgery
• Cl.perfringes: gas gangrene
• Pseudomonas: burn, tracheostomy wounds, UTI

6. FCPS : JAN 21
SBA: In hospital admitted pt with burn, which organism is responsible for
infection?
a. Staph. Aureus
b. Strep. Pyogens
c. Cl.perfringes
d. Pseudomonas
e. ALL
ANS: D

7. FCPS : JAN 20
SBA: A 25 yr old boy came with erythematous spreading lesion on 4th POD of
facial biopsy.most common organism responsible for this?
a. Pseudomonas
b. Strep.pyogens
c. Staph aureus
d. Viridens streptococci
e. Bacteroids fragilis
ANS: B

8. Classification of sources of infection
● Endogenous: present in or on the host e.g. SSSI following
contamination of the wound from a perforated appendix
● Exogenous: acquired from a source outside the body such as
the operating theatre (inadequate air filtration, poor
antisepsis) or the ward (e.g. poor hand-washing compliance).
The cause of hospital acquired infection (HAI)

9. Contd:
Microorganisms are normally prevented from causing infection in
tissues by intact epithelial surfaces, most notably the skin. These
surfaces are broken down by trauma or surgery. In addition to these
mechanical barriers, there are other protective mechanisms, which can
be divided into:
● chemical: low gastric pH;
● humoral: antibodies, complement and opsonins;
● cellular: phagocytic cells, macrophages, polymorphonuclear cells and
killer lymphocytes.

10. contd
• Bacteria doesn’t fulfill Koch’s
pustulates:
1. M.leprae
2. M.TB
3. T.pallidum
4. N.gonorrhea
5. Sal.typhi
6. Chlamydia
7. viruses

11. Surgical site infection (SSI)
Infection acquired from the environment or the staff following surgery or
admission to hospital is termed hospital acquired infection (HAI).
There are four main groups:
1. Respiratory infections (including ventilator-associated pneumonia)
2. Urinary tract infections (mostly related to urinary catheters)
3. Bacteraemia (mostly related to indwelling vascular catheters)
4. SSIs.
• A major SSI is defined as a wound that either discharges significant
quantities of pus spontaneously or needs a secondary procedure to drain
it.Systemic signs such as tachycardia, pyrexia and a raised white cell count.

13. IMPORTANT TABLE

14. B & L : 26th edition

15. VVVI

17. B & L : 26th

18. GAS GANGRENE
• Gas gangrene is caused by C. perfringens. These gram-positive, anaerobic, spore-bearing bacilli are widely
found in nature, particularly in soil and faeces. This infection is particularly relevant to military and trauma
surgery. Patients who are immunocompromised, diabetic or have malignant disease are at greater risk,
particularly if they have wounds containing necrotic or foreign material, resulting in anaerobic conditions.
Military wounds provide an ideal environment as the kinetic energy of high-velocity missiles or shrapnel
causes extensive tissue damage.Gas gangrene wound infections are associated with severe local wound pain
and crepitus (gas in the tissues, which may also be visible on plain radiographs). The wound produces a thin,
brown, sweet-smelling exudate, in which Gram staining will reveal bacteria. Oedema and spreading
gangrene follow the release of collagenase, hyaluronidase, other proteases and alpha toxin. Early systemic
plications with circulatory collapse and organ failure follow if prompt action is not taken.

19. SYNERGISTIC SPREADING GANGRENE (SYNONYM:
SUBDERMAL GANGRENE, NECROTISING FASCIITIS)
This condition is not caused by clostridia. A mixed pattern of organisms is responsible:
coliforms, staphylococci, Bacteroides spp., anaerobic streptococci and peptostreptococci
have all been implicated, acting in synergy.
Abdominal wall infections are known as Meleney’s synergistic gangrene and scrotal
infections as Fournier’s gangrene. Patients are almost always immunocompromised.
• The wound initiating the infection may have been minor, but severely contaminated
wounds are more likely to be the cause. Severe wound pain, signs of spreading
inflammation with crepitus and smell are all signs of the infection spreading. Broad-
spectrum antibiotic therapy must be combined with aggressive circulatory support.

20. Contd:

21. Pharma

22. FCPS : JAN - 21
SBA: A pt came to opd with a injury to hand which was 24 hour ago & Rt
hand is swollen , odematous, bulky ,which is the most common organism
responsible for this?
a. Staph. Aureus
b. Strep .pyogens
c. Pseudomonas
d. Saprophyticus
e. Cl.perfringes
Ans: e