Lethargy & Anorexia Following Foreign Body Surgery

Clinical History & Signalment

Tucker, a 6-year-old, 56.9-lb (25.8-kg) neutered male German shepherd crossbreed, was presented for vomiting and lethargy of 24 hours’ duration. A distal jejunal foreign body was suspected on abdominal radiographs and confirmed with exploratory laparotomy. Enterotomy was performed without complication. Cefoxitin (22 mg/kg IV) was administered 30 minutes before surgery and again every 90 minutes until surgery was complete.^1-4 Postsurgical antimicrobial administration was deemed unnecessary because the bowel was healthy and intact at the foreign body site, and there was no abdominal contamination by GI material.^5,6 Tucker recovered uneventfully and was discharged after 48 hours. Five days later, the owners noticed purulent discharge at the surgical incision site. He was also reported to be progressively lethargic and anorexic, although vomiting had not been observed.

Tucker was returned 7 days postoperatively for assessment of the abdominal incision.

Physical Examination

On presentation, Tucker was quiet but alert and responsive. Vital signs were normal except for an elevated rectal temperature (103.3°F [39.6°C]). CBC and serum chemistry profile were unremarkable other than mild leukocytosis (15.3 × 10⁹/L, reference range 5.0-14.1) characterized by mature neutrophilia (13.0 × 10⁹/L, reference range 2.9-12.0).

Examination of the surgical incision showed generalized erythema, pain and heat on palpation, and purulent discharge and dehiscence of the wound at the cranial aspect (Figure 1). A point-of-care sonogram revealed scant abdominal fluid consistent with a postoperative procedure. Surgical exploration of the wound was recommended.

FIGURE 1

Appearance of Tucker’s wound on presentation

DIAGNOSIS:

Deep Surgical Site Infection

Diagnosis

Tucker was placed under general anesthesia, and sterile wound preparation, debridement, and exploration were performed. Tissue devitalization and necrosis were noted to extend subcutaneously with involvement of the superficial abdominal musculature, leading to a diagnosis of deep surgical site infection (SSI).^3,7

Sharp debridement of necrotic tissue, thorough lavage with sterile saline, and a deep tissue swab were performed for cytology, which revealed gram-positive cocci and gram-negative rods. A small portion of the deep tissue was also excised for culture and susceptibility testing.

Treatment & Long-Term Management

Open wound management was performed with twice-daily, medical-grade honey dressings. Enrofloxacin (10 mg/kg IV) and ampicillin (20 mg/kg IV) were administered based on cytology results and the anticipated spectrum of activity against gram-positive cocci and gram-negative bacilli. Drug therapy was transitioned to amoxicillin/clavulanic acid (20 mg/kg PO every 12 hours) and enrofloxacin (10 mg/kg PO every 24 hours) after surgical recovery. Following initiation of local wound management and antimicrobial therapy, Tucker showed evidence of clinical improvement with a reduction in periwound erythema and exudative discharge. Broad-spectrum antimicrobial therapy is recommended while waiting for culture and susceptibility testing results; antimicrobial de-escalation is encouraged (see Discussion) after results are received.⁸

Culture results (see Table 1: Tucker's Culture & Susceptibility Results) obtained 2 days after Tucker was readmitted revealed an SSI with evidence of methicillin-resistant Staphylococcus pseudintermedius, extended spectrum β-lactamase–producing Enterobacter cloacae, and Enterococcus faecalis. S pseudintermedius is the leading cause of SSI in dogs with methicillin resistance; this is an increasing concern in veterinary medicine and highlights the need for prudent antimicrobial use.⁹ Decisions to change antimicrobials should be made based on culture and susceptibility results in conjunction with the patient’s clinical signs.¹⁰ Antimicrobial de-escalation (ie, enrofloxacin continued; amoxicillin/clavulanic acid discontinued) was warranted based on reported susceptibility of the isolated methicillin-resistant S pseudintermedius and E cloacae. Despite the intermediate susceptibility of S pseudintermedius to enrofloxacin, this was considered an appropriate antimicrobial choice given Tucker’s clinical improvement. Enterococcus spp were not targeted because they are not commonly true pathogens, although they are commonly isolated.¹¹

TUCKER’S CULTURE & SUSCEPTIBILITY RESULTS

*Growth level: 4 = large, 3 = moderate

^†S = susceptible, I = intermediate, R = resistant

Antimicrobial therapy was continued for 5 days until the wound was clean and dry, the periwound erythema was resolved, and a healthy bed of granulation tissue was observed. Delayed secondary closure of the wound was performed without any complications.

Prognosis & Outcome

The incision was completely healed when Tucker was presented 2 weeks after discharge for suture removal. This case demonstrates that, with appropriate and timely intervention, the prognosis for complicated SSI can be good to excellent.

Discussion

There are many risk factors for development of SSI; however, key factors include time of clipping prior to surgery, duration of anesthesia and surgery, comorbidities, surgical wound classification, and appropriate perioperative antimicrobial administration.^1,3 To minimize the risk for SSI, perioperative administration of antimicrobials should be timed so that bactericidal concentrations reach the appropriate tissue at the time of incision and throughout the duration of the procedure.¹² 

Standard SSI definitions are critical for accurate diagnosis and play an important role in surgical site surveillance programs.⁷ Active surveillance programs allow monitoring for SSI and trending of procedures with which SSI is commonly associated. Clear guidelines have been established in human medicine and subsequently adopted in veterinary medicine (see Table 2: Surgical Site Infection Definitions).^3,7

SURGICAL SITE INFECTION DEFINITIONS^3,7

TISSUE SAMPLING TECHNIQUES¹¹

Accurate diagnosis of SSI relies on an appropriate sampling technique.¹ It is preferable to perform deep tissue sampling away from active draining tracts that are likely to be contaminated with skin commensals. This can be achieved using standard wound swabs, by aspirating deep tissue, or surgically (see Table 3: Tissue Sampling Techniques), depending on the patient. Flocked swabs (vs traditional cotton-tipped swabs) can be used to maximize sample collection and results, particularly if the yield is expected to be low.¹³ Sampling should ideally occur prior to antimicrobial administration; however, if this is not practical, antimicrobials can be withheld for 24 hours prior to sampling, or the sample can be obtained just prior to when the drug is given next.¹⁴

Local wound management is significant in managing SSI and is important for effective treatment.¹⁰ Surgical intervention may not be necessary in patients with a first-time, superficial SSI that does not have extensive tissue involvement. Normal wound management practices should be applied and aimed at improving the local environment to favor healing. No strict criteria exist for surgical debridement use in the management of SSI, and clinician discretion is required. However, further exploration should be considered in severe, recurrent, or chronic infectious processes.¹ Repeated debridement may be necessary, as bacterial biofilms can rapidly recover (in ≈24 hours) and prove highly resistant to systemic antimicrobial therapy.¹

FIGURE 2

Z-technique for tissue sampling

Cytology should be performed in all SSI patients and should be compared with culture results to help determine relevance. Consideration of culture results should be based on whether isolates are common causes of infection, resident organisms at the site, or common contaminants. Consideration should also be given to the clinical response to initial antimicrobial treatment.

Antimicrobial de-escalation generally refers to a reduction in the spectrum of administered antimicrobials. Although no specific recommendations exist, studies have shown that antimicrobial de-escalation is not associated with poorer outcomes.⁸ Because it is expected to improve antibiotic resistance profiles and reduce antibiotic-related adverse events, antimicrobial de-escalation should be recommended in all cases when possible.⁸ Culture results are essential in effective de-escalation strategies and for improving patient outcomes through reducing inappropriate antimicrobial selection.^11,15 Tissue culture should be performed in all patients with suspected SSI, except those that have sporadic superficial SSI that can be managed with local therapy alone.¹⁰