Leclercia adecarboxylata Bacteremia in a Trauma Patient: Case Report and Review of the Literature

Case Report

A 55-year-old male victim of assault was found unresponsive by law enforcement personnel. There was a positive loss of consciousness of indeterminate duration. A history of alcoholism resulting in numerous arrests, angina, and hypertension was obtained from law enforcement personnel and prior hospitalization records. The patient was transported to our tertiary-care facility with a Glasgow Coma Scale score of 4 points. Right facial ecchymosis and right peri-orbital edema were present, and the patient was intubated. Other injuries detected on admission included a right nasal bone fracture, grade 1 splenic laceration, bilateral subdural hematomas, subarachnoid hemorrhage, intra-ventricular hemorrhage, fractures of ribs 6 and 7 on the right and 7–10 and 12 on the left, and a possible right middle lobe pneumonia or contusion. A chest tube was placed on the left for suspected pneumothorax, and the patient was transferred to the intensive care unit. Shortly after his arrival there, an intracranial pressure monitor was placed.

Intracranial pressures remained <20 mm Hg, and the intracranial monitor was removed on hospital day 1. Sputum and blood samples were obtained for microbiological examination on hospital day two because of fever, but no organisms were observed. On hospital day four, the patient was again febrile to 39°C and became hypotensive and tachycardic. The right subclavian central venous catheter was removed, and blood, bronchoalveolar lavage, and urine samples were obtained for culture.

Two of two blood samples from hospital day four produced gram-negative bacilli determined to be Leclercia adecarboxylata by MIC VITEK 2 (bioMérieux, Durham, NC). Two of two central venous catheter cultures also returned L. adecarboxylata. Antibiotic susceptibilities for all cultures of L. adecarboxylata were identical: ampicillin (≤2 susceptible), cefazolin (≤4 susceptible), cefoxitin (≤4 susceptible), ceftriaxone (≤1 susceptible), ciprofloxacin (≤0.25 susceptible), gentamicin (≤1 susceptible), tobramycin (≤1 susceptible), co-trimoxazole (≤20 susceptible), amikacin (≤2 susceptible), cefepime (≤1 susceptible), ampicillin/sulbactam (≤2 susceptible), imipenem/cilastatin (≤1 susceptible), piperacillin/tazobactam (≤4 susceptible), and ertapenem (≤0.5 susceptible). Both 3+ Streptococcus pneumoniae and 3+ Haemophilus influenzae were cultured from the bronchoalveolar lavage sample from hospital day four. The S. pneumoniae was susceptible to all tested antibiotics.

Vancomycin 1 g intravenously (IV) every 12 h, piperacillin-tazobactam 3.375 g IV every 6 h, and azithromycin 500 mg daily IV were initiated for broad-spectrum antimicrobial coverage prior to receipt of the gram stain and culture results. The patient's respiratory function continued to decline, and he was placed on high-frequency oscillatory ventilation (HFOV). A Swan-Ganz catheter was placed. The patient became progressively hypotensive and required vasopressin, phenylephrine, and norepinephrine for blood pressure support in addition to aggressive fluid resuscitation.

Early on the morning of hospital day five, the patient developed atrial fibrillation and was cardioverted electrically, and amiodarone and diltiazem were given. On hospital day five, dobutamine was added for cardiac output augmentation, and continuous renal replacement therapy was initiated for acute kidney injury. The patient was negative for human immunodeficiency virus, hepatitis B, and hepatitis C infections. A urinary Legionella antigen assay was negative.

Hemodynamically, the patient began to improve, all pressors were withdrawn by the end of hospital day five, and HFOV was ceased on hospital day seven. The Swan-Ganz catheter was removed on hospital day eight as the patient's blood pressure continued to stabilize. The patient ultimately received each days of vancomycin, piperacillin-tazobactam, and azithromycin therapy. Cefazolin 1 g every 8 h was started after the cessation of the previous antibiotics and was continued for five days to complete a 10-day treatment of the L. adecarboxylata bacteremia. Cefazolin was chosen to complete the antibiotic course because of its narrower spectrum of activity and the susceptibility results on MIC Vitek 2. Blood cultures after cessation of antibiotic therapy demonstrated no organisms. The patient underwent percutaneous tracheostomy and percutaneous endoscopic gastrostomy tube placement on hospital day 10 secondary to failure to wean from conventional ventilation. On hospital day 15, the patient was transferred to the floor with a tracheostomy collar. The patient was decannulated on hospital day 51 and transferred to an inpatient rehabilitation facility on hospital day 58.

Discussion

Leclercia adecarboxylata is a member of Enterobacteriaceae and was originally described as a member of the genus Escherichia until DNA and protein electrophoresis techniques allowed separation of the organism into its own genus, Leclercia [1,2]. Leclercia adecarboxylata exhibits many characteristics typical of other Enterobacteriaceae, being gram-negative, a facultative anaerobe, oxidase-negative, catalase-positive, mesophilic, and peritrichous [4]. Isolates of L. adecarboxylata react with indole and acetoin and ferment sorbitol [5].

There have been 23 case reports of infection by L. adecarboxylata since 1991 to our knowledge (Table 1). Similar to other opportunistic members of the Enterobacteriaceae, the disease presentation of L. adecarboxylata is varied and appears more often in patients who have underlying immunosuppression or are experiencing a polymicrobial infection. Of the 31 patients described in the case reports, 21 were immunosuppresed in some respect. Only 14 of the 31 infections were described as polymicrobial. Although previous authors have argued that the polymicrobial environment observed with some L. adecarboxylata infections suggests dependence of L. adecarboxylata on other pathogens, this association more likely represents the overall impedance to appropriate immune function in an immunosuppressed host [3]. The route L. adecarboxylata uses to gain access to the host is unclear and likely not unifocal, as evidenced by the numerous and varied locations yielding the organism.

Leclercia adecarboxylata is naturally sensitive to tetracyclines, aminoglycosides, most β-lactams, quinolones, folate pathway inhibitors, and azithromycin but resistant to penicillin G, oxacillin, many macrolides, lincosamides, streptogramins, linezolid, rifampicin, and fosfomycin [4]. The mechanism of resistance to fosfomycin is unclear; resistance to the other agents likely represents drug exclusion by the bacterial outer membrane, as is typical of many Enterobacteriaceae [4]. Resistance to ampicillin is reported commonly [7,8,12,15,19]. Two case reports describe isolates with extended spectrum β-lactamase activity and resistance to several aminoglycosides, ampicillin, and piperacillin, among others [7,12]. Although most isolates of L. adecarboxylata appear to be susceptible to a wide range of agents, the development of extended-spectrum β-lactamase resistance is disheartening because of the potential for horizontal transfer, particularly in the setting of polymicrobial infections [4].

With the advent of modern rapid molecular typing techniques, recognition of L. adecarboxylata as a causative agent in infection is likely to become more common. The present case involved an immunosuppressed individual who developed a catheter-related blood stream infection caused by L. adecarboxylata and provides additional evidence supporting the association between L. adecarboxylata infection and immunosuppression. As the diagnosis of L. adecarboxylata continues to improve with molecular and genomic techniques, further interactions between L. adecarboxylata, polymicrobial infections, and the immunosuppressed patient are likely to be elucidated.