When the bite bites back: A rare mimic of epidural site infection.

Dear Editor, Epidural anaesthesia is among the most commonly utilised regional anaesthetic techniques, offering reliable perioperative analgesia with an excellent safety profile.[] Nonetheless, catheter-related complications, including insertion site infections, may occur in approximately 0.5–2% cases.[] Hard ticks are obligate blood-feeding ectoparasites. Their saliva induces characteristic local inflammatory reactions, including erythema, warmth, oedema, and a central punctum (closely resembling early signs of superficial bacterial infection).[] We describe an unusual case in which a post-operative epidural site inflammation presented such a diagnostic and therapeutic dilemma. A 45-year-old multiparous woman with adenomyosis was scheduled for total laparoscopic hysterectomy with high probability of conversion to open surgery. Pre-anaesthetic evaluation revealed American Society of Anesthesiologists (ASA) I physical status, and the patient consented to combined epidural–general anaesthesia. Standard monitoring was connected. During painting of the lumbar region with povidone iodine, an insect was noted on the lateral lumbar region. The surgeon removed it and sent it to the microbiology department for identification. As the skin of the back was normal, epidural catheterisation was performed at the T12–L1 interspace under full aseptic precautions. General anaesthesia was subsequently induced, and the surgery succeeded uneventfully laparoscopically itself. Post-operatively, the patient was transferred to the ward with the epidural catheter in situ for analgesia. As the surgeon planned to start heparin on day 0, the epidural catheter was removed after giving top-up, on the same evening. On post-operative day 1 at night, we received a call regarding epidural site infection. The patient had developed low-grade fever and malaise. Local examination revealed localised patches of erythema, warmth, and mild tenderness over the mid to lower back [Figure 1]. The initial differential diagnosis included 1) irritant contact dermatitis from povidone iodine, 2) epidural catheter site infection, or 3) epidural abscess. No catheter site discharge or neurological deficits were noted (excluding epidural abscess). Laboratory investigations revealed a mildly elevated leukocyte count (total leucocyte count – 12.8 × 109/L) with other parameters within normal limits. No abdominal rash or erythema was present, helping to exclude widespread irritant dermatitis owing to povidone iodine, also used to paint the surgical field. The patient was already started on antibiotics (injection ceftriaxone and metronidazole) post-operatively; however, the patient’s local symptoms persisted. On post-operative day 2, the microbiology report identified the submitted specimen as a hard tick (Ixodes). Dermatology consultation revealed a rash suggestive of early Lyme disease. Tablet doxycycline 100 mg twice daily was started for a course of 2 weeks, to which the patient responded favourably. A skin biopsy was suggested for establishing the definitive diagnosis for Lyme disease but was declined by the patient due to clinical improvement. Over the next 5 days, the patient’s fever, erythema, and discomfort improved drastically. She was discharged without further complications. A majority of epidural site infections result from bacterial contamination. These are mostly caused by Gram-positive organisms including Staphylococcus aureus (methicillin-resistant), Staphylococcus epidermidis, Streptococcus pneumoniae, and Gram-negative bacteria—Escherichia coli and so on. Atypical aetiologies include fungal pathogens (Candida, Aspergillus) and ectoparasitic and viral infections (rare).[] Early post-operative fever and erythema can have multiple causes.[] However, clinicians often prioritise identification of procedure/device-related complications, which may overshadow alternate causes such as ectoparasite borne as in our case. Tick bites produce inflammation mediated by salivary proteins, potentially indistinguishable from early cellulitis or superficial infection.[] Diagnostic challenges in atypical aetiologies include delayed recognition, further leading to unwarranted delays in treatment. Misdiagnosis can lead to inappropriate therapeutic interventions. Non-bacterial aetiologies may not respond to standard antibiotic therapy. The positive dermatological assessment and microbiology identification (owing to the surgeon’s mindfulness to send the insect for evaluation) helped reveal the ectoparasitic aetiology. This case underscores the importance of comprehensive examination and maintaining a high index of suspicion for atypical causes, particularly in endemic areas. Early identification of arthropod involvement can prevent unnecessary treatment (empirical antibiotic use), improve patient outcomes, and enhance tick-borne disease surveillance. Presentation at conferences/CMEs and abstract publication None. Study data availability Not applicable. Disclosure of use of artificial intelligence (AI)-assistive or generative tools No AI tools were used. Declaration of use of permitted tools Snipping tool was used for editing the image. Author contributions AB: Data collection, manuscript writing and revision. PM: Manuscript writing and revision. HSB: Data collection. All authors were involved in the concept and final approval of the manuscript. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. REFERENCES 1. 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