http://surgerybook.net/

Ampicillin/sulbactam is not recommended because of high resistance of Escherichia coli to this agent

(B-II)

Cefotetan and clindamycin are not recommended for use because of increasing resistance of the

Bacteroides fragilis group to these agents (B-II)

Because of the availability of less toxic agents demonstrated to be of at least equal efficacy,

aminoglycosides are not recommended for routine use in community-acquired IAI in adults (B-II).

Healthcare-Associated Complicated Intra-Abdominal Infection

For patients with “healthcare-associated” cIAI, separate evidence-based guideline recommendations for

empiric antimicrobial treatment are provided (Algorithm 8-1). Specific antimicrobials are recommended

based on whether the patient and/or institution have high risk for infection with multidrug-resistant

pathogens. Quinolone-resistant E. coli have become common in many communities, and quinolones

should not be used unless hospital antibiograms confirm greater than 90% susceptibility of E. coli to

quinolones. In patients with healthcare-associated cIAI, carbapenems are an excellent single-agent

regimen for empiric treatment.

Table 8-5 Empiric Antimicrobial Treatment of Extrabiliary cIAIs, Community

Acquired

Duration of Antibiotics for Complicated Intra-Abdominal Infection

8 Duration of antibiotics for treatment of cIAI has long been controversial. A recent important

randomized controlled trial examined the efficacy of short-course (4 days) antimicrobial therapy in

patients with intra-abdominal infections who had undergone an adequate source control procedure.

Fixed-duration antibiotic therapy for 4 days was noninferior to longer duration antmicrobial therapy

until resolution of physiologic abnormalities, with no difference in the composite endpoints of SSI,

recurrent intra-abdominal infection, or death.8

SPECIFIC INTRA-ABDOMINAL INFECTIONS

Appendicitis

Appendicitis is common with over 300,000 hospital discharges in the United States per year. Although

appendectomy provides definitive source control for the treatment of acute nonperforated appendicitis,

238

http://surgerybook.net/

intravenous (IV) antibiotics should be administered preoperatively with a dose repeated

intraoperatively if the surgery is prolonged, a number of controversies in diagnosis and management of

appendicitis persist.9

Antibiotics versus Appendectomy

In patients with uncomplicated appendicitis (nonperforated, no abscess, or phlegmon), appendectomy is

definitive source control. But a number of recent randomized trials have confirmed that acute

nonperforated appendicitis can be treated successfully with antibiotics alone. A meta-analysis of 6

studies with 1,201 patients reported that in patients treated with antibiotics alone, 7 ± 4% failed to

respond and required appendectomy, and acute appendicitis recurred in 14 ± 11%. A normal appendix

was found in 7.3 ± 5.1% of patients at appendectomy. Complications were considerably less likely to

occur with antibiotic treatment than with appendectomy. Major surgical complications included

enterocutaneous fistula and reoperation.10

Algorithm 8-1. Empiric antimicrobial treatment of extrabiliary cIAIs, community acquired versus healthcare associated. (Adapted

from Solomkin JS, Mazuski JE, Bradley JS, et al. Diagnosis and management of complicated intra-abdominal infection in adults

and children: guidelines by the Surgical Infection Society and the Infectious Diseases Society of America. Surg Infect (Larchmt)

2010;11(1):79–109.)

A Cochrane meta-analysis of 5 trials with 901 patients reported that 73.4% of patients who were

treated with antibiotics and 97.4% patients underwent appendectomy were cured within 2 weeks

without major complications (including recurrence) within 1 year.11 Another meta-analysis included

only four trials and reported that efficacy was significantly higher for surgery but rates of perforated

appendicitis were not different, and complication rates were significantly higher for surgery.12

The most recent trial (APPAC) enrolled 530 patients in Finland with uncomplicated appendicitis

confirmed by CT scan and randomized to early appendectomy or antibiotic treatment (ertapenem for 3

days, then oral levofloxacin and metronidazole for 7 days) with 1-year follow-up. In the antibiotic

group, 70 patients (27.3%) underwent appendectomy within 1 year of initial presentation for

appendicitis. Antibiotic treatment did not meet the prespecified criterion for noninferiority compared

239

http://surgerybook.net/

with appendectomy. But it was notable that 72.7% of patients with uncomplicated appendicitis treated

with antibiotics alone did not require subsequent appendectomy.13,14

The trials published to date were primarily from European countries, used antibiotics not available in

the United States and had minimal use of laparoscopic appendectomy or CT scan for diagnostic

imaging.15 Further high-quality randomized trials are therefore needed to determine which patients are

most likely to benefit from antibiotic therapy alone. Although appendectomy remains the standard

treatment for acute appendicitis, antibiotic treatment alone may be used as an alternative treatment in

patients with contraindication to surgery (or where surgery is high risk).

Laparoscopic versus Open Appendectomy

Appendectomy can be performed by laparoscopic or open approach. A large retrospective review

(2005–2008) of laparoscopic versus open appendectomy using the American College of Surgeons

National Surgical Quality Improvement Program (NSQIP) reported that 76.4% were performed

laparoscopically and 23.6% performed open. Open appendectomy was associated with increased

morbidity, SSI, and mortality.16

A Cochrane review of 67 trials was updated in 2010 and reported that laparoscopic appendectomy

was associated with lower SSI rates but higher intra-abdominal abscess rate. Laparoscopic approach was

associated with shorter hospital length of stay, faster return to normal activity, and decreased

postoperative pain. This review concluded that laparoscopic appendectomy should be considered the

preferred approach where surgical expertise and equipment are available.17

Time to Appendectomy and Perforation Risk

It has long been thought that appendiceal luminal obstruction leads to appendiceal perforation without

timely surgical intervention. This belief led to attempts to decrease time from presentation and

diagnosis of acute appendicitis to operating room start time. With the advent of early appropriate

empiric systemic antimicrobial therapy, this fundamental concept is no longer true. As discussed

previously, in patients with uncomplicated appendicitis, antibiotic treatment alone does not lead to

appendiceal perforation. Furthermore, using data from the Washington State Surgical Care and

Outcomes Assessment Program (SCOAP) with 9,048 adult patients who underwent appendectomy, there

was no association between appendiceal perforation and in-hospital time prior to surgery. This study

confirmed that appendiceal perforation is most commonly a prehospital occurrence, and timing of

surgery should be determined based on all factors relevant to the surgeon and patient.18

Abscess or Phlegmon Management

In patients with periappendiceal abscess or phlegmon, current evidence (mainly retrospective studies)

supports nonoperative management with IV transitioned to oral antibiotics and percutaneous drainage if

possible. A meta-analysis of 19 retrospective studies from 1969 to 2005 reported that nonsurgical

treatment failed in only 7.6% of patients and immediate appendectomy was associated with higher

morbidity. Similar findings were confirmed in a more recent review.19 Routine interval appendectomy

is not recommended since the risk of recurrence is low (7.4%). But either colonoscopy or repeat CT

imaging is recommended due to the risk of a malignant disease (1.2%) or important benign disease

(0.7%) identified during follow-up.20

240

http://surgerybook.net/

Algorithm 8-2. Biliary infections and algorithm for diagnosis and management. (From Demehri FR, Alam HB. Evidence-based

management of common gallstone-related emergencies. J Intensive Care Med 2016;31(1):3–13.)

Interval Appendectomy after Initial Nonoperative Management

A large retrospective cohort study reported that 3% of patients were initially treated with nonoperative

management. Of these, 15% had an interval appendectomy and the remaining 85% did not. Of the 864

patients that did not undergo interval appendectomy only 39 patients (5%) had recurrence of

appendicitis after a median follow-up of 4 years.21 Routine interval appendectomy after initial

successful nonoperative treatment is therefore not justified and should be abandoned. In a meta-analysis

including 2,771 patients initially treated nonoperatively for appendiceal phlegmon or abscess, 31

patients were found to have a malignant diagnosis and a lower rate of inflammatory bowel disease.

These data highlight the need for follow-up with either CT scan or colonoscopy after successful

nonoperative management.20 Although a retrospective study in pediatric appendicitis reported a 2.8-fold

higher rate of recurrent appendicitis in patients with an appendicolith, this study is limited by small

sample size (n = 96) and a higher overall rate of recurrent appendicitis than all other published

studies.22 See also chapter on Appendiceal Diseases.

Biliary Infections

Biliary infections include acute cholecystitis which may be calculous or acalculous, may include

choledocholithiasis or not, and cholangitis.23 Acute cholecystitis and ascending cholangitis are primary

inflammations of the gallbladder and bile ducts, respectively, which are caused by infection and possible

biliary obstruction.

Acute Cholecystitis

Acute cholecystitis is inflammation of the gallbladder resulting from obstruction of the cystic duct and

subsequent bacterial invasion and overgrowth. Cholelithiasis is the cause of cystic duct obstruction in

more than 90% of cases of acute cholecystitis in the United States. Acalculous cholecystitis is more

common in critically ill patients and the pathophysiology is transmural ischemia. Acalculous

cholecystitis carries higher morbidity and mortality rates than calculous cholecystitis.

The diagnosis of acute cholecystitis is made based on the common constellation of right upper

quadrant tenderness, leukocytosis, and fever. Initial diagnostic imaging is right upper quadrant

ultrasound to evaluate for gallstones, gallbladder wall thickening, and pericholecystic inflammation

(sensitivity 88% to 94%, specificity 78% to 80%). If ultrasound is inconclusive or is discordant with the

241