First described in 1962, Leclercia adecarboxylata is a motile gram-negative bacterium that belong to the Enterobacteriaceae family1. As it is rarely pathogenic in immunocompetent hosts, the organism has primarily been described in cases of bacteremia, pneumonia, and wound infections in immunocompromised patients2,3. However, modern methods of identification have increased the rate of identification of this pathogen. In musculoskeletal injury, L. adecarboxylata has been described only in the context of penetrating or open wounds and in association with contaminated water, frequently in the lower limbs4-9. In this case report, we present the first case of an immunocompetent patient infected with this Bacillus following orthopedic surgical treatment for a closed fracture. The case suggests that L. adecarboxylata should be considered as a potential pathogen in orthopedic surgery.
The patient was informed that data concerning the case would be submitted for publication, and she provided consent. After consulting with the institutional review board (IRB), it was determined that IRB approval was not necessary for this case report.
A 65-year-old healthy community-ambulating female with no prior surgical history, chronic condition, or history of infection presented to the emergency department status post mechanical trip and fall onto her left outstretched arm on a busy metropolitan sidewalk. Radiographs taken upon presentation revealed a left closed displaced intra-articular olecranon fracture (Fig. 1) and a left nondisplaced greater tuberosity humerus fracture. She subsequently underwent operative open reduction and internal fixation of the olecranon and nonoperative treatment of the left proximal humerus. The patient received 2 g prophylactic intravenous cefazolin intraoperatively. Her index surgery was uneventful and stable fixation was achieved. A tension band plate was utilized to repair the olecranon fracture. The wound was irrigated and closed in a routine fashion. As there was no suspicion of contamination or infection, intraoperative cultures were not collected. Following surgery, the patient was placed in a long-arm splint and discharged the same day.
The patient returned 2 weeks post-operatively and her sutures were removed. Uneventful wound healing was noted at this point without motor or sensory defect. There was no noted erythema or warmth at the incision site. Radiographs were not taken at this time. Range of motion of her left elbow was limited at this time, and she was prescribed physical therapy for range of motion.
Four weeks post-operatively, the patient presented to our hospital's orthopedic urgent care clinic due to increased erythema and warmth at the wound site. The patient denied any numbness, tingling, fever, or chills at this time. There was no noted active drainage or wound dehiscence; however, the wound was warm to the touch and a 4-cm rim of erythema surrounding the incision site was present. She was started on a 10-day course of oral sulfamethoxazole/trimethoprim and cephalexin at this time and instructed to return for further wound inspection in 1 week. Upon returning one week later, the erythema had worsened, with blanching erythema now noted over much of the extensor surface of the elbow. Clinical photographs were taken at this time (Fig. 2). The left elbow was warm to the touch, with a one-inch site of fluctuance at the proximal pole of the incision. She was indicated for operative irrigation and debridement. Infection labs were taken at this time, demonstrating erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and white blood cell (WBC) count within normal range (Table I).
TABLE I -
Infection Lab Results Taken Post-operatively*†
|Time from Initial Fixation
||WBC Count (K/µL)
|Clinical reference range
CRP = C-reactive protein, ERC = erythrocyte sedimentation rate, IV = intravenous, and WBC = white blood cell.
Results in bold are abnormal.
After 2 weeks on IV ceftriaxone.
The patient underwent operative irrigation and debridement with retention of hardware under general anesthesia. Deep wound cultures were taken and sent to pathology, and a drain was placed prior to closure. Following surgery, she had a peripherally inserted central catheter (PICC) line placed into the right basilic vein and was started on a tentative 6-week course of intravenous (IV) vancomycin 1,000 mg every 12 hours + IV piperacillin-tazobactam 3.375 g every 6 hours empirically following a consult with an infectious diseases specialist. Serologies again demonstrated normal ESR and CRP at this time. Two days later, aerobic deep wound cultures converted positive for monomicrobial L. adecarboxylata species. The specimen was susceptible to all antibiotics tested. No other specimens were identified. The vancomycin and piperacillin-tazobactam regimen was stopped at this time, and the patient was started on a 6-week course of IV ceftriaxone at 2 g every 24 hours.
Two weeks following the irrigation and debridement, the patient presented to the ED with a fever and weakness and reported weight loss of 7 pounds over the previous 2 weeks. Laboratorytests taken at this time demonstrated nonelevated ESR and CRP, but decreased WBC (2.1 K/μL) and marked neutropenia (29% neutrophil) (Table I). After consulting infectious disease, the IV ceftriaxone was discontinued and the patient was started on IV ertapenem at 1 g every 24 hours. The course of ertapenem was continued for 4 weeks and the patient's neutropenia and apparent adverse antibiotic reaction improved. No signs of ongoing infection were noted during this time, and ESR and CRP remained nonelevated.
Four months following her initial fixation surgery, the patient returned to the clinic. Her infection had clinically resolved at this time; however, she reported a left ulnar nerve symptoms with numbness and intrinsic weakness in the left hand. Her olecranon fracture and humerus fracture were clinically and radiographically healed at this time (Fig. 3). She was indicated for operative removal of hardware, debridement, and ulnar nerve decompression. The operation was uneventful, and deep wound cultures were taken. All cultures were negative and the patient reported resolution of her ulnar nerve symptoms at 2 weeks post-operatively. The patient returned to the clinic at 6 months and 1 year following her initial fracture and reported no residual symptoms or pain. All signs of infection and neutropenia had completely resolved.
This report describes a rare case of L. adecarboxylata being isolated from an immunocompetent patient following orthopedic surgery. In addition, the case also reports a rare neutropenic adverse reaction to IV ceftriaxone in treatment of this infection. L. adecarboxylata is a gram-negative bacilli that was first isolated from drinking water and described by Leclerc in 1962 who named the organism Escherichia adecarboxylata1. The pathogen has since been reclassified and is now recognized as being a normal part of the flora of the gut of animals, in the stool of humans, and widely distributed in food and water10. Historically, the pathogen has been described as minimally virulent and rarely pathogenic11. In cases reported in the literature, infections with L. adecarboxylata occur most frequently in immunocompromised patients or in polymicrobial infections suggesting its typical dependence on either an immunocompromised host or co-flora to cause pathogenic disease12. As such, the bacterium has been classified by some in the literature as solely an opportunistic pathogen, although we now know this not to be true13. In a recent review of the literature, Forrester et al. reported that 31 cases of L. adecarboxylata have been discussed in the literature at the time of their review, with 21 of the 31 patients immunosuppressed in some respect and 14 of the 31 being described as polymicrobial infections9. Of interest, only one report included both an immunocompetent patient and a monomicrobial infection with L. adecarboxylata, and this was following an open puncture wound and subsequent exposure to open water14. Since this time, there have been several additional reports of infection with L. adecarboxylata in the literature. Just 3 such reports have discussed monomicrobial infection in immunocompetent patients; one reports a pharyngeal and peritonsillar abscess involving L. adecarboxylata in a chronic tobacco chewer11, while the other 2 report penetrating open injury7,15. Of these penetrating injury cases, the report from Grantham et al. is the only report in the orthopedic literature involving L. adecarboxylata and describes a monomicrobial L. adecarboxylata infection in an immunocompetent child following puncture wound with a foreign object near open water15.
Our case presents an instance in which L. adecarboxylata has been isolated from a patient following orthopedic surgery. Further, it reports a case of a monomicrobial post-operative infection of L. adecarboxylata in an immunocompetent host in any surgical field. While prior reports involving musculoskeletal injury include either open or penetrating wounds, this patient sustained a closed fracture. This report suggests that L. adecarboxylata may be considered in post-operative orthopedic infection.
L. adecarboxylata can lead to symptomatic, monomicrobial infection in immunocompetent patients following orthopedic surgery. Orthopedic surgeons and clinical microbiology departments should be aware of this potentially emerging pathogen and attempt to culture and identify this species to allow for the timely diagnosis and proper treatment for patients infected with this pathogen.
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