Septic shock caused by Leptotrichia buccalis in a neutropenic patient secondary to chemotherapy

We present the case of a 55-year-old male, a major smoker and drinker with T4aN1M0 supraglottic squamous cell carcinoma, a subcutaneous reservoir carrier and peripheral venous access for chemoradiotherapy treatment. A week after receiving the first cisplatin cycle, he came to the emergency department and was transferred to the ICU for septic shock (fever, hypotension, decreased level of consciousness, procalcitonin of 46 ng/ml and lactate of 5.47 mmol/l) with severe hydroelectrolytic disorders (hyponatraemia, hypokalaemia, hypochloraemia, hyperglycaemia and metabolic acidosis), acute renal failure and severe bicytopaenia (leukopaenia of 300, with 60 neutrophils and thrombocytopenia of 19,000) without coagulopathy.

Supportive treatment was initiated with crystalloids, platelet transfusion, vasoactive amines and empirical intravenous antibiotic therapy with piperacillin–tazobactam and subsequently with meropenem, amikacin and linezolid. He presented a torpid evolution, rapid atrial fibrillation and respiratory failure with poor response despite mechanical ventilation and amiodarone infusion. He died within a few hours following a cardiorespiratory arrest and multiple organ failure.

Chest X-ray showed bilateral infiltrate (Fig. 1).

Fig. 1.

Bilateral alveolar infiltrate on chest radiography upon admission.

In the blood cultures obtained on admission, a long, fusiform and microaerophilic Gram-negative bacillus grew in all the bottles. Growth was slow and, at 48 h, the colony was small, grey and well-defined. It was identified as Leptotrichia buccalis using mass spectrometry (MALDI-TOF).

Leptotrichia spp. is a Gram-negative bacillus; sometimes it has been described as a large variable, immobile, facultative anaerobic, fusiform, carbohydrate fermenter and lactic acid producer. Some species do not grow in conventional media and when they do they are slow growing. Identification by phenotypic methods is difficult, and, therefore, it is believed that their infections are underdiagnosed¹ as they are identified as Fusobacterium or Lactobacillus. It is currently identified by mass spectrometry or by sequencing the 16S rRNA gene. L. buccalis resides mainly in the oral cavity so it usually causes dental diseases and oral abscesses, although in immunosuppressed patients it acts as an opportunistic pathogen.² It has a taxonomic similarity to fusobacteria, which is why they formerly belonged to the same family.^1–3 The pathogenicity of Leptotrichia spp. is due to the production of LPS and secretion of endotoxins that trigger an inflammatory reaction by cytokines.²

In a recent review⁴ isolates of this bacterium have been described in cases of sepsis, neutropenic fever, thrombocytopaenia, subacute dyspnoea, halitosis and various dental diseases (pulpitis or pulp necrosis, periodontitis, dental plaques, etc.) and even endocarditis.⁵ An increased risk of bacteraemia due to L. buccalis has been reported in patients with febrile neutropenia after chemotherapy and mucositis or periodontal infections.^6,7 The patient we present had oral sepsis and missing teeth, in addition to the laryngeal tumour with local invasion.

There are published cases of Lemierre's syndrome due to L. buccalis in neutropenic patients⁸ with bilateral radiological infiltrates and pulmonary abscesses on CT. In our case, after the rapid fatal outcome and the absence of consent for necropsy, the study could not be completed, but, despite its rarity, we do not rule out this possibility. In the differential diagnosis we also include bilateral atypical pneumonia⁹ from L. buccalis due to severe sepsis, respiratory failure and compatible radiology.

It is usually susceptible to multiple antimicrobial agents such as beta-lactam, carbapenems, clindamycin, metronidazole, rifampin, tetracyclines and chloramphenicol,^1,4,6,7 and resistant to aminoglycosides, macrolides, vancomycin and fluoroquinolones.^4,10

We believe that our contribution is important because there is no published case of septic shock due to L. buccalis. Most of the cases with bacteraemia described in the literature also had post-chemotherapy neutropenia, and the point of entry was the oral cavity. However, all of them had responded to the aforementioned antibiotics, unlike our patient.