Surgical Infections

1. Surgical Infections Joseph Castellano M.D. 9/29/09

2. Definition • Infections that require surgical intervention to resolve completely • Infections that develop as a complication of surgery • Caused by the invasion, resident, and proliferation of pathogens such as bacteria, viruses and fungi.

3. Outcomes of Microbial Invasion • Eradication • Containment leads to abscess (furuncle, carbuncle, hidradenitis suppurativa, intra-abdominal abscesses) • Locoregional infection (cellulitis, soft tissue infection, lymphangitis) • Systemic infection (bacteremia, fungemia)

4. Furuncle • Cutaneous staph abscesses • Bacterial colinization begins in hair follicles and can cause cellulitis and abscess formation • Treatment with surgical drainage if large, antibiotics +/-

5. Carbuncles • Cutaneous abscess that spreads through the dermis into subcutaneous region • Common with diabetics • Treatment with I & D, antibiotics +/-

6. Intra-abdominal infection • Primary microbial peritonitis • Ascities, peritoneal dialysis • Tx: antibiotics • Secondary microbial peritonitis: contamination of the peritoneal cavity due to perforation or severe inflammation and infection of an intra-abdominal organ • Appendicitis, diverticulitis, perforation, etc. • therapy requires source control to resect the diseased organ; débridement of necrotic, infected tissue and debris; and administration of antimicrobial agents directed against aerobes and anaerobes

7. Intra-abdominal infection • Patients in whom standard therapy fails develop an intra-abdominal abscess, leakage from a gastrointestinal anastomosis leading to postoperative peritonitis, or tertiary (persistent) peritonitis. • Intra-abdominal abscess: perc drain vs. surgical intervention, short course of antibiotics

8. Organ Specific Infections • Hepatic abscesses • 80% pyogenic, 20% parasitic and fungal • Pyogenic abscess treated with sampling and 4-6 weeks of antibiotics, larger abscesses may need perc drain.

9. Organ Specific Infections • Pancreatic necrosis • Develops in 10-15% of patients who develop severe hemorrhagic pancreatitis • Sterile and Infected necrosis • empiric antibiotic therapy with carbapenems or fluoroquinolones that achieve high pancreatic tissue levels reduce the incidence and severity of pancreatic infection • enteral feedings initiated early, using nasojejunal feeding tubes – prevents translocation of bacteria

10. Organ Specific Infections • Secondary pancreatic infection • Suspected in patients whose systemic inflammatory response (fever, elevated WBC count, or organ dysfunction) fails to resolve, or in those individuals who initially recuperate, only to develop sepsis syndrome 2 to 3 weeks later • CT-guided aspiration or identification of gas within the pancreas on CT scan, mandate operative intervention • 50% mortality if no surgical intervention if infected necrosis • Lower mortality in sterile necrosis

11. Cellulitis • Inflammation of the dermal and subcutaneous tissues secondary to nonsuppurative bacterial invasion. • Redness, edema, and localized tenderness • May infect the lymphatics leading to lymphangitis • Treatment against Group A strep

12. Necrotizing Fasciitis • Rapidly progressive, multiple organisms, invades fascial planes • Causes vascular thrombosis as it progresses, resulting in necrosis of the tissues involved. • Overlying skin may be normal • Hemorrhagic bullae may develop from edema; crepitus; systemic toxicity • “dishwater gray” discharge with anaerobic infection • Group A strep, mixed anaerobes + coliforms, MRSA • Treatment is surgical debridement, send gram stain • Vanc, carbapenems, and Pen G

13. Surgical Site Infection • 38% of nosocomial infections, 2-5% of patients • Factors: • Health of the patient • Operative technique • Timely administration of preoperative antibiotics • No benefit to antiseptic bath over other wash products • No benefit to barrier devices except gloves • Good surgical techniques: gentle traction, hemostasis, removal of devitalized tissue, obliteration of dead space, irrigation, wound closure without tension

14. Risk Factors Microorganism: Remote site infection, long term care facility, duration of the procedure, wound class, ICU patient, prior antibiotic therapy, preop shaving, bacterial number, virulence, and antimicrobial resistance Local Wound: Surgical technique – Hematoma/ seroma, necrosis, sutures, drains, foreign bodies Patient: Age, immunosuppression, steroids, malignancy, obesity, diabetes, malnutrition, multiple comorbidities, transfusions, cigarette smoking, oxygen, temperature, glucose control

15. Risk Factors • Drains: • Should be omitted after hepatic, colonic, or rectal resection with primary anastomosis and after appendectomy for any stage of appendicitis • Should be used after esophageal resection and total gastrectomy • Contamination increases with duration of operation • Electrocautery: pinpoint coagulation, dividing tissue under tension decreases tissue destruction

16. Surgical Site Infection • Difference is SSI based on hand hygiene? Hand rubbing vs. hand scrubbing • Compliance 44% vs 28%

17. Wound classification • Clean wounds were defined as uninfected operative wounds in which no inflammation was encountered and the wound was closed primarily. By definition, a viscus (respiratory, alimentary, genital, or urinary tract) was not entered during a clean procedure. • Clean-contaminated wounds were defined as operative wounds in which a viscus was entered under controlled conditions and without unusual contamination. • Contaminated wounds included open, fresh accidental wounds, operations with major breaks in sterile technique or gross spillage from a viscus. Wounds in which acute, purulent inflammation was encountered also were included in this category. • Dirty wounds were defined as old traumatic wounds with retained devitalized tissue, foreign bodies, or fecal contamination or wounds that involve existing clinical infection or perforated viscus.

18. Antibiotic Prophylaxis • Timing: Percent of SSI for dose given early, preoperative, perioperative, and postop are 3.8, 0.6, 1.4 and 3.3 respectively • Prophylaxis with cefazolin has been effective for most clean procedures. Cefuroxime can be given for thoracic and ortho procedures. • For procedures that might involve bowel anaerobes, cefoxitin is more effective than cefazolin.

19. ABX Recs • Colon/Whipple: Bowel prep/oral prophylaxis/ IV prophylaxis • Neomycin, Erythromycin, Cefoxitin • Cholecystectomy open or laparoscopic prophylaxis recommended for pt age>60, previous biliary surgery, acute symptoms, jaundice (benefit less clear with lap): cefoxitin or unasyn • Uncomplicated appendectomy: cefoxitin or unasyn • Penetrating abdominal trauma: Cefoxitin or Unasyn – continue post op for 24 hours • IHR: uncomplicated, no prophylaxis; complicated, cefoxitin • Mastectomy: no abx recommended • Vascular cases: Cefazolin

20. Other Recs • Esophageal and gastroduodenal: Cefazolin • ERCP: routine abx prophylaxis does not reduce sepsis/cholangitis • Repeat dosing: Procedure lasting more than 4 hours or when major blood loss occurs • Continuation of Abx past 24 hours post op is not recommended • Hair removal with clippers immediately preop • Preop or postop hyperglycemia increase risk of SSI • Perioperativenormothermia

21. Postoperative Nosocomial Infections UTI Pneumonia Bacteremic Episodes Sepsis Syndrome

22. UTI Diagnosis should be considered with urinalysis positive for WBCs, bacteria, or a positive leukocyte esterase. Confirmed with culture > 10K colonies in symptomatic patient or > 100K colonies in asymptomatic patient Treatment with 10-14 days with a single antibiotic that achieves high levels in the urine is appropriate Remove catheter

23. Pneumonia High risk with prolonged mechanical ventilation Frequently multi-resistant organisms Diagnosis by Xray BAL with gram stain and culture Antibiotics based on local antibiogram with beta-lactam, aminoglycoside or fluoroquinolone, and vanc or linezolid. Treat for 7-8 days

24. Bacteremic Episodes • Indwelling catheters • 25% of catheters will become colonized, and 5% will be associated with bacteremia • Prolonged insertion, insertion under emergency conditions, manipulation under nonsterile conditions, and perhaps the use of multilumen catheters increase the risk of infection. • Confirmed with blood culture from peripheral site and catheter that grow same bacteria • Treatment is removal of catheter. • In patients with difficult access and grow low virulence bugs, such as S. epidermidis, treatment with 14-21 days of antibiotics is effective 50-60% of the time.

25. Sepsis Syndrome • Empiric antimicrobial therapy, institution specific • Fluid rescucitation • Metabolic support • Site specific infection control • Appropriate therapy associated with two to three fold reduction in mortality • Low dose steroid for patients with hypotension refractory to vasopressors • STIM test • Hydrocortisone 100mg/8hr vs. continuous infusion • Xigris associated with 6% reduction in mortality • antithrombotic, profibrinolytic, and anti-inflammatory properties • Consider in patients with severe infection and at least one organ failing