SR 27 - Surgical Infection Flashcards
Define cellulitus
Blanching erythema from superficial dermal/epidermal infection
Define a superinfection
New infection arising while a patient is receiving antibiotics for teh original infection at a different site
What is the most common nosocomial infection?
UTI
What is the most common nosocomial infection leading to death?
Respiratory tract infection (pneumonia)
What constitutes a positive urine analysis?
Positive nitrite
Positive leukocyte esterase
>10 WBC/HPF
Presence of bacteria (supportive)
What number of CFU confirms the diagnosis of UTI?
100,000 (10^5) CFU
What are the common organisms for UTI?
E. coli, klebsiella, proteus
Enterococcus, staphylococcus aureus
What is the treatment for UTIs?
Antibiotics with gram-negative spectrum (i.e. Bactrim, gentamicin, ciprofloxacin, aztreonam)
Check culture and sensitivity - adjust meds from there
What is the treatment for bladder candidiasis?
Remove or change foley catheter
Administer systemic fluconazole or give amphotericin bladder washings
What are the signs of a central line infection?
Unexplained hyperglycemia
Fever, mental status change, hypotension, tachycardia
Shock
Pus and erythema at central line site
What is the most common cause of ‘catheter-related bloodstream infections’?
Coagulase-negative staphylococcus (33%)
Enterococci, Staphylococcus aureus, gram-negative rods
When should central lines be changed?
When they are infected
There is NO advantage to changing them ever 7 days
What central line infusion increases the risk of infection?
Hyperal (TPN)
What is the treatmetn for central line infection?
Remove central line, send for culture
+/- IV antibiotics
Place new central line in a different place
When should peripheral IV short angiocatheters be changed?
Every 72-96 hours
What is a surgical site infection?
When do they arise?
Infection in an operative wound
POD 5-7
Signs and symptoms of surgical site infections?
Pain at incision site, erythema, drainage, induration, warm skin, fever
What is the treatment for surgical site infections?
Remove skin sutures/staples Rule out fascial dehiscence Pack wound open Send wound culture Administer antibiotics
What are the most common bacteria found in post-op wound infections?
Staph aureus (20%)
E. coli (10%)
Enterococcus (10%)
Others - staph epidermidids, pseudomonas, anaerobes, gram -, streptococcus
Which bacteria cause fever and wound infection in the first 24 hours after surgery?
Streptococcus
Clostridium (bronze-brown weeping tender wound)
What is the definition of a ‘clean’ wound? Infection rate?
Elective, nontraumatic wound without acute inflammation
usually closes primarily without the use of drains
What is the definition of a ‘clean-contaminated’ wound? Infection rate?
Operation on GIT or RT withou unusual contamination or entry into the biliary or urinary tract
What is the definition of a ‘contaminated’ wound? Infection rate?
Acute inflammation, traumatic wound, GIT spillage, or a major break in sterile technique
5% infection rate
What is the definition of a ‘dirty’ wound? Infection rate?
Pus present, perforated viscus or dirty traumatic would
33% infection rate
What are the possible complications of wound infections?
Fistula, sinus tracts, sepsis, abscess, suppressed wound healing, superinfection, hernia
What factors influence the development of infections?
Foreign body (i.e. suture, drains, grafts)
Decreased blood flow (poor delivery of PMNs and antibiotics)
Strangulation of tissues with excessively tight sutures
Necrotic tissue or excessive local tissue destruction
Long operation (>2 hrs)
Hypothermia in OR
Hematomas or seromas
Dead space that prevvents the delivery of phagocytic cells to bacterial foci
Poor approximation of tissues
What patient factors influence the development of infections?
Uremia Hypovolemic shock Vascular occlusive states Advanced age Distant area of infection
What are examples of an immunosuppressed state?
Immunosuppressant treatment Chemotherapy Systemic malignancy Trauma or burn injury Diabetes mellitus Obesity Malnutrition AIDS Uremia
What lab tests are indicated with a surgical wound infections?
CBC - leukocytosis or leukopenia (an abscess may act as a WBC sink)
Blood cultures
Imaging studies (i.e. CT scan to locate an abscess)
What is the treatment for surgical wound infections?
Incision and drainage - an abscess must be drained
Antibiotics for deep abscesses
What are the indications for antibiotic after drainage of a subcutaneous abscess?
DM, surrounding cellulitis, prosthetic heart valve or immunocompromised state
(flucuation is a sign of a subcutaneous abscess)
What are the causes of a peritoneal abscess?
Postoperative status after a laparotomy, ruptured appendix, peritonitis, any inflammatory intraperitoneal process, anastomotic leak
What are the common sites for peritoneal abscesses?
Pelvis Morison's pouch Subprenic Paracolic gutters Periappendiceal lesser sac
What are the signs/symptoms of a peritoneal abscess?
Fever (classifcally spiking)
Abdominal pain
Mass
How is the diagnosis of peritoneal abscess made? When should you look?
Abdominal CT scan or ultrasound
POD 7
What CT scan findings are associated with abscesses?
Fluid collection with fibrous rind
Gas in fluid collection
What is the treatment for a peritoneal abscess?
Percutaneous CT-guided drainage
For pelvic abscess - transrectal/transvaginal drainage
All abscesses must be drained except which type?
Amebiasis
Pre-treatment with surgical removal
Define necrotizing fasciitis
Bacterial infection of underlying fascia
Spreads rapidly along fascial planes
What are the causative agents for necrotizing fasciitis?
GAS (S. pyogenes)
But often polymicrobial with anaerobes/G- organisms
What are the signs and symptoms of necrotizing fasciitis?
Fever, pain, crepitus, cellulitis, skin discoloration, blood blister, weeping skin, increased WBCs
Subcutaneous air on X-ray
Septic shock
What is the treatment for necrotizing fasciitis?
IVF IV antibioitics Aggressive early, extensive surgical debridement Cultures Tetanus prophylaxis
What is clostridial myositis?
Clostridial muscle infection
AKA Gas gangrene
Due to Clostridium perfringens
What are the signs and symptoms of clostridial myositis?
Pain, fever, shock, creptius
Foul-smelling brown fluid
Subcutaneous air on X-ray
What is the treamtent of clostridial myositis?
IV antibiotics
Aggressive surgical debridement of involved muscle
Tetanus prophylaxis
What is suppurative hidradenitis? Where do they occur?
Infection/abscess formation in apocrine sweat glands
Perineum/buttock, inguinal area, axillae (sites of aprocrine glands)
What is the causative organisms in suppurative hidradenitis?
S. aureus
What is the treatment for suppurative hidradenitis?
Antibiotics
Incision and drainage (excision of skin with glands for chronic infections)
What is pseudomembranous colitis?
Antibiotic-induced colonic overgrowth of C. difficile, secondary to loss of competitive nonpathogenic bacteria that comprise the normal colonic flora
(Esp. penicillins, cephalosporins, clindamycin)
Caused by exoctoxin release by C. difficile
What are the signs and symptoms of pseudomembranous colitis?
Diarrhea (10% bloody)
+/- fever, increased WBCs, abdominal cramps, abdominal distention
How do you diagnose pseudomembranous colitis?
Stool assy for exotoxin titer
+/- fecal leukocytes
On colonoscopy, you see a membranous exudate
What is the treatment of pseudomembranous colitis?
PO metronidazole or PO vancomycin
Discontinuation fo causative agents
NEVER give antiperistaltics
What are hte indications for prophylactic IV antibiotics?
Accidental wounds with heavy contamination and tissue damage
Accidental wounds requring surgical therapy that has had to be delayed
Prosthetic heart valve or valve disease
Penetrating injuries of hollow intra-abdominal organs
Large bowel resections and anastomosis
Cardiovascular surgery with the use of a prosthesis/vascular procedures
Patients with open fractures (start in ER)
Traumatic woudns occuring >8 hours prior to medical ttention
What must a prophylactic antibotic cover for procedures on teh large bowel/abdominal trauma/appendicitis?
Anaerobes
What commonly used antibiotics offer anaerobic coverage?
Cefoxitin (Mefoxin) Clindamycin Metronidazole (Flagyl) Cefotetan Ampicillin-sulbactum (Unasyn) Zosyn Timentin Imipenem
What antibiotic is used prophylactically for vascular surgery?
Ancef
significant PCN allergy - erythromycin or clindamycin
When is the appropriate time to administer prophylactic antibiotics?
Adequate blood levels prior to surgical incision
What is parotitis? Bug?
Infection of the parotid gland
Staphylococcus
Factors associated with increased risk for parotitis?
>65yo Malnutrition Poor oral hygiene Presence of NG tube NPO dehydration
When does parotitis most commonly occur?
2 weeks postoperatively
Signs of parotitis?
Hot, red, tender parotid gland
Increased WBCs
What is the treatment of parotitis?
Antibiotics
Operative drainage, as necessary
What is a ‘stitch’ abscess?
Subcutaneous abcess centered around a subcutaneous stitch, which is a foreign body
Treat with drainage and stitch removal
What bacteria to be found in the colon?
Anaerobic - bacteroides fragilis
Aerobic - E. coli
Which bacteria are found in infections from human bites?
Strep viridans, S. aureus, Peptococcus, Eikenella
Treat with Augmentin
What is the most common ICU pneumonia bacteria?
Gram-negative organisms
What is Fournier’s gangrene?
Perineal infection starting classifcally in the scrotum in patients with diabetes
Treat with triple antibiotics adn wide debridement - surgical emergency
Does adding antibiotics to peritoneal lavage solution lower the risk of abscess formation?
No
What are the classic antibiotics for ‘triple’ antibiotics?
Ampicillin, gentamycin, metronidazole (Flagyl)
What antibiotic is used to treat amoeba infection?
Metronidazole (Flagyl)
What bacteria commonly infect prosthetic material and central lines?
Staphylococcus epidermis
What is the antibiotic of choice for Actinomyces?
Penicillin G
What is a furnucle?
Staph abscess that forms in a hair follicle
What is a carbuncle
Subcutaneous staph abscess, suusally an extension of a furuncle
Most commonly seen in patients with diabetes
what is a felon
Infection of the finger pad
What are the signs of tetanus?
Lockjaw, muscle spasm, laryngospasm, convulsions, respiratory failure
What are the appropriate prophylactic steps in tetanus-prone injury in patients who have three previous immunizations
None
Tetanus toxid only if >5 years since last toxoid
What are the appropriate prophylactic steps in tetanus-prone injury in patients who have two previous immunizations?
Tetanus toxoid
What are the appropriate prophylactic steps in tetanus-prone injury in patients who have one previous immunization?
Tetanus immunoglobulin IM and tetanus toxoid IM (different sites)
What are the appropriate prophylactic steps in tetanus-prone injury in patients who have no previous immunizations?
Tetanus immunoglobulin IM and tetanus toxoid IM (different sites)
