Infection in Surgical Patients

1
Infection in Surgical Patients

• August, 2006
• Mike Joutovsky, PGY3
• Department of Surgery
• St. Barnabas Hospital

2
(No Transcript)
3
(No Transcript)
4
(No Transcript)
5
(No Transcript)
6
(No Transcript)
7
Defense Barriers

• Physical
• Chemical
• Immunologic

8
Host defense

• Barrier
• Microbial flora
• Humoral
• Cellular
• cytokine

9
Microbial flora
10
Humoral defenses

• Immunoglobulin
• Complement

11
Immunoglobulin

• All Ig classes (IgM, G, A, E, D and igG
  subclasses are composed of one type (M,G,A,E,D)
  of heavy (H) and one type of light (L) protein.
• Each L chain is linked to an H chain, and H
  chains are interlinked.
• H chain activate complement or bind to receptors
  of either macrophages or PMN leucocytes
• The amino terminus of the H and L chains together
  forms antigen-binding site

12
Immunoglobulin
13
Complement system

• Series of serum proteins that may became
  activated via either classic or alternative
  pathway

14
(No Transcript)
15
Cellular defense

• Macrophage
• PMN leucocytes
• cytokines

16
Surgical Site Infection ( SSI )
17
Clinical criteria ( CDC )

• A purulent exudate draining from the surgical
  site
• A positive fluid culture obtained from a surgical
  site that was closed primarily
• The surgeons diagnosis of infection
• A surgical site that requires reopening

18
FACTS

• One out of every 24 patients who have inpatient
  surgery in the United States has a postoperative
  SSI
• The cost of SSIs are substantial an increased
  total cost of more than 300
• SSIs increase the post operative length of
  hospital stay by 10-14 days

19
Definition

• SSI is a difficult term to define accurately
  because it has a wide spectrum of possible
  clinical features
• Its hard to define, but I know it when I see
  it.
• SSI are classified into three categories,
  depending of which anatomic areas are affected

20
(No Transcript)
21
Definitions of SSI

• Superficial incisional SSI Infection involves
  only skin and subcutaneous tissue of incision.
• Deep incisional SSI Infection involves deep
  tissues, such as fascial and muscle layers. This
  also includes infection involving both
  superficial and deep incision sites and
  organ/space SSI draining through incision.
• Organ/space SSI Infection involves any part of
  the anatomy in organs and spaces other than the
  incision, which was opened or manipulated during
  operation.

22
Causes

• Table 1. Pathogens Commonly Associated with Wound
  Infections and Frequency of OccurrencePathogen
  Frequency () NNIS System (CDC, 1996)

23
Risk factors

• Decreased host resistance can be due to systemic
  factors affecting the patient's healing response,
  local wound characteristics, or operative
  characteristics.
• Systemic factors include age, malnutrition,
  hypovolemia, poor tissue perfusion, obesity,
  diabetes, steroids, and other immunosuppressants.
  
• Wound characteristics include nonviable tissue in
  wound hematoma foreign material, including
  drains and sutures dead space poor skin
  preparation, including shaving and preexistent
  sepsis (local or distant).
• Operative characteristics include poor surgical
  technique lengthy operation (gt2 h)
  intraoperative contamination, including infected
  theater staff and instruments and inadequate
  theater ventilation prolonged preoperative stay
  in the hospital and hypothermia

24
The type of procedure is a risk factor too
25
Antimicrobial agents

• Prophylaxis
• Empiric therapy
• Directed therapy

26
Classes of Antimicrobial Agents

• Penicillins, Cephalosporins, carbapenems inhibit
  cell wall synthesis, resulting in bacteriolysis
• Tetracyclins, chloramphenicol, and macrolides
  inhibit bacterial ribosomal activities and thus
  overall protein synthesis
• Vanco inhibits assembly of peptido glycan
  polymers
• Quinolones inhibit bacterial DNA synthesis

27
Prophylactic Antibiotics

• General agreement exists that prophylactic
  antibiotics are indicated for clean-contaminated
  and contaminated wounds
• Antibiotics for dirty wounds are part of the
  treatment because infection is established
  already.
• Clean procedures might be an issue of debate. No
  doubt exists regarding the use of prophylactic
  antibiotics in clean procedures in which
  prosthetic devices are inserted because infection
  in these cases would be disastrous for the
  patient.

28
Systemic preventive antibiotics should be used in
the following cases

• A high risk of infection is associated with the
  procedure (eg, colon resection).
• Consequences of infection are unusually severe
  (eg, total joint replacement).
• The patient has a high NNIS risk index.

29

• The antibiotic should be administered
  preoperatively but as close to the time of the
  incision as is clinically practical. Antibiotics
  should be administered before induction of
  anesthesia in most situations.
• The antibiotic selected should have activity
  against the pathogens likely to be encountered in
  the procedure.
• Postoperative administration of preventive
  systemic antibiotics beyond 24 hours has not been
  demonstrated to reduce the risk of SSIs

30
Intraoperative re-dosing

• Operation is prolong
• If massive blood loss occurs
• The patient is obese

31
Colorectal Surgery

• Recommended oral prophylaxis consist of Neomycin
  plus erythromycin or Neomycin plus Flagyl, along
  with administration of mechanical bowel
  preparation
• Intravenous cefoxitin or cefazolin preoperatively
  and continued 2 doses or 24 hrs postoperatively

32
Intraabdominal Infection

• Usually polymicrobial
• There is synergism between aerobic and anaerobic
  organisms
• Peritonitis vs abscesses formation
• Abscesses
• Determined by gravity and the physiologic
  drainage basins of the abdomen
• Subphrenic space, pelvic space, subhepatic space,
  paracolic gutter, lesser sac, subfascial area

33
Primary Peritonitis

• Microorganisms lodge in the peritoneal cavity
  without a fundamental intraabd. Process
• Previously occurred in miliary TB, but now
  commonly occurs in ascites
• Most common organism in ascties is S. pneumoniae

34
Secondary peritonitis

• Usually begins with perforation of the GI tract
• From inflammatory or neoplastic process
• One major factor in determining severity is the
  size of the bacterial inoculum
• Perforated appendix has 106 to 107 bacteria per g
• Sigmoid colon has 1010 to 1011 bacteria per g
• Anaerobes exceed aerobes 1,000-fold
• Adjuvant factors are also important
• Food, fiber, exfoliated cells, blood, dead tissue
• Bacteria that are eliminated are either
  phagocytized or removed into the lymphatic system

35
Tertiary Peritonitis

• recurrent intra-abdominal infection after initial
  surgical and antimicrobial therapy of secondary
  bacterial peritonitis.

36
Nosocomial Pneumonia

• Comes from atelectasis, aspiration, and
  contamination from ventilation
• Most common bacteria
• Pseudomonas, Klebsiella, Staph, E. coli, Proteus,
  Enterobacter, Pneumococcus, Serratia, group A
  Strep, H. flu

• Host defenses
• Glottis
• Cilia
• Mucus
• Secretory IgA and IgG
• Surfactant
• Transferrin
• Alveolar macrophages

37
Urinary Tract Infections

• Foley catheterization is usually the culprit
• Host defenses
• Urine flow, antireflux, epithelium, mucus, IgA,
  urethral length
• Common organisms
• E. coli, Klebsiella, Pseudomonas, Proteus,
  Enterobacter, Enterococcus, Serratia,
  Citrobacter, Staph epidermidis

38
Catheter and Prosthetic Device Infection

• The trauma of the catheter placement, the foreign
  body itself, and the contaminating bacteria lead
  to an inflammatory response
• Eradication cannot be achieved because of the
  persistence of the foreign body
• Intimal vein disruption and clot formation also
  lead to bacterial proliferation
• Removal should never be delayed nor should
  antimicrobial agents be withheld

39
Other Specific Site Infection

• Parotitis
• Sinusitis
• Pseudomembranous colitis

40
(No Transcript)