Surgical Infection Flashcards
What are the classic signs and symptoms of inflammation or infection?
Tumor, Calor, Dolor, Rubor
What is bacteremia?
Bacteria in the blood
What is SIRS?
Systemic Inflammatory Response Syndrome:
Fever, tachycardia, tachypnea, leukocytosis
What is sepsis?
Documented infection and SIRS
What is septic shock?
Sepsis and hypotension
What is cellulitis?
Blanching erythema from superficial dermal or epidermal infection (usually strep more than staph)
What is an abscess?
Collection of pus within a cavity
What is a superinfection?
New infection arising while a patient is receiving antibiotics for the original infection at a different site
What is a nosocomial infection?
Infection originating in the hospital
What is empiric antibiotic treatment?
Use of antibiotics based on previous sensitivity information or previous experience awaiting culture results in an established infection
What is prophylactic antibiotic treatment?
Antibiotics used to prevent an infection
What is the most common nosocomial infection?
UTI
What is the most common nosocomial infection causing death?
Pneumonia
What diagnostic tests are used for UTIs?
U/A, urine culture, urine microscopy for WBC
What constitutes a positive U/A?
Positive nitrite (from bacteria), positive leukocyte esterase (from WBC), > 10 WBC/HPF, presence of bacteria (supportive)
What number of colony-forming units (CFU) confirms the diagnosis of UTI?
On urine culture, classically 100,000 CFU
What are the common organisms in UTIs?
E. coli, Klebsiella, Proteus, (Enterococcus, Staphylococcus aureus)
What is the treatment for UTIs?
Antibiotics with gram-negative coverage (e.g. sulfamethoxazole/trimethoprim, gentamicin, ciprofloxacin, aztreonam).
Check culture and sensitivity.
What is the treatment of bladder candidiasis?
- Remove or change Foley catheter
2. Administer systemic fluconazole or amphotericin bladder washings
What are the signs of a central line infection?
Unexplained hyperglycemia, fever, mental status change, hypotension, tachycardia, pus, 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 every 7 days in non-burn patients.
What central line infusion increases the risk of infection?
Hyperal (TPN)
What is the treatment for central line infection?
- Remove central line (send for culture) +/- IV antibiotics.
- Place new central line in a different site.
When should peripheral IV short angiocatheters be changed?
Every 72-96 hours
When doe wound infections arise?
Classically, PODs #5-7
What are the signs and symptoms of wound infections?
Pain at incision site, erythema, drainage, induration, warm skin, fever
What is the treatment for wound 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 postoperative wound infections?
Staphylococcus aureus (20%), E. coli (10%), Enterococcus (10%) Others: Staphylococcus epidermidis, Pseudomonas, anaerobes, other gram-negatives, Streptococcus
Which bacteria cause fever and wound infection in the first 24 hours after surgery?
- Streptococcus
2. Clostridium (bronze-brown weeping tender wound)
What is a clean wound?
Elective, non-traumatic wound without acute inflammation.
Usually closed primarily without the use of drains.
What is the infection rate of a clean wound?
< 1.5%
What is a clean-contaminated wound?
Operation on the GI or respiratory tract without unusual contamination or entry into the biliary or urinary tract
Without infection present, what is the infection rate of a clean-contaminated wound?
< 3%
What is a contaminated wound?
Acute inflammation, traumatic wound, GI tract spillage, or a major break in sterile technique
What is the infection rate of a contaminated wound?
5%
What is a dirty wound?
Pus present, perforated viscus, or dirty traumatic wound
What is the infection rate of a dirty wound?
33%
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 (e.g. 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 operations (> 2 hrs); hypothermia in OR; hematomas or seromas; dead space that prevents 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; obesity; malnutrition; AIDS; uremia
Which lab tests are indicated for wound infections?
CBC (leukocytosis or leukopenia), blood cultures, imaging (CT to locate abscess)
What is the treatment for wound infections?
I&D, antibiotics for deep abscesses
What are the indications for antibiotics after drainage of a subcutaneous abscess?
Diabetes, surrounding cellulitis, prosthetic heart valve, or an immunocompromised state
What is a peritoneal abscess?
Abscess within the peritoneal cavity
What are the causes of peritoneal abscesses?
Postoperative status after a laparotomy, ruptured appendix, peritonitis, any inflammatory intraperitoneal process, anastomotic leak
What are common sites for peritoneal abscesses?
Pelvis, Morison’s pouch, subphrenic, paracolic gutters, periappendiceal, lesser sac
What are the signs and symptoms of peritoneal abscesses?
Fever (classically spiking), abdominal pain, mass
How is the diagnosis of peritoneal abscess made?
Abdominal CT (or U/S)
When should an abdominal CT be obtained looking for a postoperative abscess?
After POD #7 (otherwise, abscess will not be organized and will look like a normal postoperative fluid collection)
What CT findings are associated with peritoneal abscess?
Fluid collection with fibrous rind, gas in fluid collection
What is the treatment for peritoneal abscess?
Percutaneous CT-guided drainage
What is an option for drainage of pelvic abscess?
Transrectal drainage (or transvaginal)
All abscesses must be drained except which type?
Amebiasis
What is necrotizing fasciitis?
Bacterial infection of underlying fascia (spreads rapidly along fascial planes)
What are the causative agents of necrotizing fasciitis
Classically, group A Streptococcus pyogenes, but most often polymicrobial with anaerobes and gram-negative organisms
What are the signs and symptoms of necrotizing fasciitis?
Fever, pain, crepitus, cellulitis, skin discoloration, blood blisters (hemorrhagic bullae), weeping skin, increased WBCs, subcutaneous air on XR, septic shock
What is the treatment for necrotizing fasciitis?
IVF, IV antibiotics and aggressive early extensive surgical debridement, cultures, tetanus prophylaxis
Is necrotizing fasciitis an emergency?
Yes, patients must be taken to the OR immediately
What is clostridial myositis?
Clostridial muscle infection
What is another name for clostridial myositis?
Gas gangrene
What is the most common causative organism of clostridial myositis?
Clostridium perfringens
What are the signs and symptoms of clostridial myositis?
Pain, fever, shock, crepitus, foul-smelling brown fluid, subcutaneous air on XR
What is the treatment for clostridial myositis?
IV antibiotics, aggressive surgical debridement of involved muscle, tetanus prophylaxis
What is suppurative hidradenitis?
Infection or abscess formation in apocrine sweat glands
In what 3 locations does suppurative hidradenitis occur?
- Perineum/buttocks
- Inguinal area
- Axillae
What is the most common causative organism of suppurative hidradenitis?
Staphylococcus aureus
What is the treatment for suppurative hidradenitis?
Antibiotics, I&D (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
What are the signs and symptoms of pseudomembranous colitis?
Diarrhea (bloody in 10%), fever, increased WBC, abdominal cramps, abdominal distention
What causes the diarrhea in pseudomembranous colitis?
Exotoxin released by C. difficile
How is the diagnosis of pseudomembranous colitis made?
Assay stool for exotoxin titer; fecal leukocytes may or may not be present; colonoscopy may show exudate that looks like a membrane
What is the treatment for pseudomembranous colitis?
PO metronidazole or PO vancomycin; discontinuation of causative agent
What are the indications for prophylactic IV antibiotics?
Accidental wounds with heavy contamination and tissue damage; accidental wounds requiring 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 procedure; patients with open fractures; traumatic wounds occurring > 8 hours prior to medical attention
What must a prophylactic antibiotic cover for procedures on the large bowel, abdominal trauma, or appendicitis?
Anaerobes
What commonly used antibiotics offer anaerobic coverage?
Cefoxitin (Mefoxin), clindamycin, metronidazole, cefotetan, ampicillin-sulbactam (Unasyn), Zosyn, Timentin, Imipenem
What antibiotic is used prophylactically for vascular surgery?
Ancef (if patient is significantly allergic to penicillin, then erythromycin or clindamycin are options)
When is the appropriate time to administer prophylactic antibiotics?
Must be in adequate levels in the blood stream prior to the surgical incision
What is parotitis?
Infection of the parotid gland
What is the most common causative organism of parotitis?
Staphylococcus
What are the associated risk factors with parotitis?
Age older than 65 years, malnutrition, poor oral hygiene, presence of NG tube, NPO, dehydration
What is the most common time of occurrence of parotitis?
Usually 2 weeks post-op
What are the signs of parotitis?
Hot, red, tender parotid gland and increased WBCs
What is the treatment for parotitis?
Antibiotics, operative drainage as necessary
What is a stitch abscess?
Subcutaneous abscess centered around a subcutaneous stitch, which is a foreign body.
Treat with drainage and stitch removal.
Which bacteria can be found in the stool?
Anaerobic: Bacteroides fragilis
Aerobic: E. Coli
Which bacteria are found in infections from human bites?
Streptococcus viridans, Staphylococcus aureus, Peptococcus, Eikenella.
Treat with Augmentin.
What are the most common ICU pneumonia bacteria?
Gram-negative organisms
What is Fournier’s gangrene?
Perineal infection starting classically in the scrotum in patients with diabetes.
Treat with triple antibiotics and wide debridement.
Does adding antibiotics to peritoneal lavage solution lower the risk of abscess formation?
No
What is the classic finding associated with a Pseudomonas infection?
Green exudate and fruity smell
What are the classic antibiotics for triple antibiotics?
Ampicillin, gentamicin, and metronidazole
Which antibiotic is used to treat amoeba infection?
Metronidazole
Which bacteria commonly infect prosthetic material and central lines?
Staphylococcus epidermidis
What is the antibiotic of choice for Actinomyces?
Penicillin G
What is a furuncle?
Staphylococci abscess that forms in a hair follicle
What is a carbuncle?
Subcutaneous staphylococcal abscess (usually an extension of a furuncle), most commonly seen in patients with diabetes
What is a felon?
Infection of the finger pad
What microscopic finding is associated with Actinomyces?
Sulfur granules
What organism causes tetanus?
Clostridium tetani
What are the signs of tetanus?
Lockjaw, muscle spasms, laryngospasm, convulsions, respiratory failure
What is the appropriate prophylactic step in a patient with a dirty wound and three previous tetanus immunizations?
None (tetanus toxoid only if > 5 years since last toxoid)
What is the appropriate prophylactic step in a patient with a dirty wound and two previous tetanus immunizations?
Tetanus toxoid
What is the appropriate prophylactic step in a patient with a dirty wound and one previous tetanus immunization?
Tetanus immunoglobulin IM and tetanus toxoid IM (at different sites)
What is the appropriate prophylactic step in a patient with a dirty wound and no previous tetanus immunizations?
Tetanus immunoglobulin IM and tetanus toxoid IM (at different sites)
What is Fitz-Hugh-Curtis syndrome?
RUQ pain from gonococcal perihepatitis in women
