Microbiology & Infectious Diseases
Interactive case study test your knowledge:
Case Presentation A previously healthy 17-year-old male was transferred to a tertiary paediatric emergency department due to concern for sepsis. The patient was febrile, tachycardic, and hypotensive. Before transfer, he was resuscitated with intravenous fluid boluses and was given a dose of ceftriaxone. Symptoms: In the preceding 5 days, the patient had fevers with chills, sore throat, odynophagia with associated trismus, emesis, and right-sided groin pain. Past Medical History: His past medical history was unremarkable, with no recent travel or sick contacts. He disclosed recent marijuana and tobacco use, and ongoing contact with four Rottweilers. His immunisations were complete up until 12 years of age; however, he was unimmunised for COVID-19.
Febrile The patient showed signs of a high fever
Tachycardic Increased heartbeat
Hypotensive The patient had low blood pressure
Case Presentation Continued... Upon admission to the authors’ hospital, the patient remained mildly tachycardic but was haemodynamically stable. Examination Findings: A few small and tender lymph nodes in the anterior cervical chain (<1.5 cm) An area of tenderness at the left angle of the mandible Oropharyngeal examination showed Grade 1 tonsils Normal cervical range of motion, but limited jaw opening of two to three finger breadths Abdominal examination revealed mild epigastric and right inguinal tenderness with no associated masses Neurological examination was unremarkable Considering the patient’s initial presentation with neck stiffness and trismus, there was a strong suspicion of a potential deep neck pathology.
CLICK to reveal: Occlusive retromandibular vein on ultrasonography
Investigations CT head and neck revealed left retromandibular vein thrombosis and infiltrative densities, suggestive of thrombophlebitis. Ultrasound and Doppler study of the neck also revealed similar findings.
Test your knowledge - Question 1: What might be the initial diagnosis made based on the imaging findings of left retromandibular vein thrombosis and infiltrative densities? Choose: A,B, C, or D
Lemierre's syndrome
Deep neck space infection
Bacterial tonsillitis
Septic thrombophlebitis
Normal
Septic Thrombosis
Investigations Bloods: Normal leukocyte count (9.5x109 cells/L) Elevated c-reactive protein (270 mg/L) Thrombocytopenia (36x109 /L) Elevated D-dimer assay (3,226 µg/L) Hyponatraemia (126 mEq/L) High creatinine (147 µmol/L)
Cultures and screening: Methicillin-resistant Staphylococcus aureus screen was negative Sexually transmitted infection screen were all negative (including HIV, syphilis, gonorrhoea, chlamydia, and hepatitis B) Serology assays for COVID-19, hepatitis B virus, hepatitis C, cytomegalovirus, Epstein–Barr virus, toxoplasmosis, Lyme, and parvovirus were all negative
Broad-spectrum Intravenous antibiotics were initiated empirically (including ceftriaxone, clindamycin, and vancomycin) due to the concern for sepsis and potential toxic shock syndrome.
Blood, throat, and urine cultures (collected after starting antibiotics) were negative.
Investigations Continued... Based on these findings, a presumptive diagnosis of Lemierre's syndrome (LS) was made. MRI of the head showed punctate diffusion restriction of the right frontal–parietal subcortical white matter, suggestive of cerebral infarction Persistent right groin pain prompted further radiological investigations. CT abdomen/pelvis showed a moderate amount of non-specific ascites
Click to reveal: MRI of the pelvis identified a right iliacus abscess measuring 2.7 cm x 3.8 cm.
HEALTHY / DISEASED
Axial view on MRI pelvis showing right iliacus abscess
Liver
Transvere colon
Small intestine
Peritoneal cavety
Stomach
Peritoneum
Investigations Continued... Culture of the fluid drained from the abscess via ultrasound-guided aspiration, while on antibiotics, was sterile.
16S ribosomal RNA (16S rRNA) PCR was also performed and confirmed the presence of Fusobacterium necrophorum.
Animation by David S. Goodsell, RCSB Protein Data Bank - Molecule of the Month at the RCSB Protein Data Bank
Test your knowledge - Question 2: Which diagnostic test would you use to confirm the presence of Fusobacterium necrophorum, the causative organism in this case of LS? Choose A,B,C, or D
Blood culture
Throat culture
Serolog assays
16S ribosomal RNA (rRNA) PCR
Test your knowledge - Question 3: What were the atypical features observed in the progression of LS in this case? Choose A,B,C, or D
The site of thrombosis was the left retromandibular vein
The patient developed a right iliacus muscle abscess
The patient experienced a cerebral infarction
All of the above
Test your knowledge - Question 4: What antibiotic regimen would be best if there is clinical suspicion of LS? Choose A, B, C, or D
Ampicillin
Ceftriaxone & Vancomycin
Azithromycin
Ceftriaxone & Metronidazole
Treatment and Management
At the 2-month follow-up: • Stable appearance of thrombus on neck ultrasound • Satisfactory clinical progress • Normal laboratory investigations
Following the clinical diagnosis of LS, antibiotics were adjusted to ceftriaxone and metronidazole
Anticoagulation with enoxaparin was initiated and later transitioned to rivaroxaban
The patient's clinical presentation improved
No neurological deficits clinically. Imaging findings were found to be clinically non-significant
Patient was discharged on the 12th day of admission with: • Intravenous ceftriaxone, administered via a peripherally inserted central catheter line, over 6 weeks • Anticoagulation therapy of 3 months
Three months post-discharge: • Patient presented with fever, neck pain, sore throat, and emesis • Repeat neck ultrasound revealed a new left internal jugular vein (IJV) thrombus • Septic workup, including blood cultures and a neck CT were negative for an infectious cause • Diagnosed with a likely viral illness and new left IJV thrombus
• It was discovered that the patient had not been adherent with medication
Test your knowledge - Question 5: What potential factor could have contributed to this recurrence? Choose A, B, C, or D
Development of a hypercoagulable state
Immune deficiency
Non-adherence to anticoagulation therapy
Persistent infection
Conclusion Two months after the second hospitalisation, and with consistent adherence to anticoagulation therapy, a repeat ultrasound showed complete resolution of the left IJV thrombus. Consequently, the patient was discharged from the paediatric haematology clinic.
Read the full case report here:
Fever, Sore Throat, and Abdominal Pain Connecting the Dots to a ‘Forgotten’ Disease: A Case Report of Atypical Lemierre’s Syndrome
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