Generalized Tetanus in a Canadian Farmer Following Orthopedic Surgery

Round 1

Reviewer 1 Report

This is a complete and very interesting presentation of an unusual case of tetanus following elective orthopaedic hip surgery.

I have only one question for the Authors: did they inform the surgeon or the hospital where the patient were operated on for this complication, as they wrote that "the mechanism for infection may have been related to his recent total left hip replacement"?

Author Response

Thank you for your interest in our paper and inquiry.

The case was handed over to the Infection Prevention and Control team at the hospital where the patient was operated on. The patient also attended a follow-up appointment with the surgeon to evaluate their prosthetic joint and recovery. However, to this date, no concrete evidence was found that the hip prosthesis was truly the source of the infection. Both infectious diseases and orthopedics services had been involved in this case and after extensive investigations, the exact mechanism of infection is not fully explained.

Reviewer 2 Report

This is an highly interesting report. The report itself is unique and original. I would like to see more comments about the entry of the infection. The authors claimed that, the mechanism for infection was unclear, but may have been related to his recent total left hip replacement. If so, was this a healthcare associated infection? If possible, I would like to learn some more details. 

Author Response

Thank you so much for your support for our paper and inquiry.

A major challenge in the presented case was determining a mechanism for infection in order to support the presumptive diagnosis. We elicited a detailed history and physical exam from the patient to identify potential exposures (as summarized in lines 35-38 in our manuscript):

• 20 days prior to presentation (12 days prior to surgery), the patient worked on his farm and rounded up cattle into a truck, but denied any scratches, scrapes, trauma or close contact with the animals
• 18 days prior to presentation (10 days prior to surgery), the patient rounded up elk with his colleague. While this was challenging work, his colleague conducted all of the animal vaccinations and ear tagging and the patient wore gloves throughout
• The patient works actively on his farm to move bales of hay with his tractor but could not recall specific contact with metal or soil or associated injuries. He had been routinely wearing gloves and a heavy coat due to cold temperatures.
• Head to toe dermatological examination revealed no scratches, scrapes, or wounds aside from the well-healed incision along his left hip which was absent erythema or warmth
• The patient had no evidence of dental caries or exudate

This inquiry reduced the likelihood of direct trauma or puncture-related tetanus entry. However, as tetanus may have harbored the patient’s skin following routine farming activities, the surgery may have presented a mechanism for spore transmission from the skin surface to the prosthetic joint despite efforts to maximize sterilization during the procedure.

Although tetanus is rare following insertion of prosthetic material, examples of the same and other orthopedic tetanus infections can be found in several case reports. We have added two additional references to our revised manuscript accordingly:

Original {Page 5, Lines 187-188}:

11. Strypstein S, Claeys S, Smet B, Pattyn P. Forgotten pathogen: Tetanus after gastrointestinal surgery. BMJ Case Reports 2019; 12. DOI: 10.1136/bcr-2019-229701.

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Revised {Page 5, Lines 193-197}:

11. Shelton D, Penciner R. Case report of an unusual source of tetanus. The Journal of Emergency Medicine 1998; 16:163–165. DOI: 10.1016/S0736-4679(97)00281-3.
12. Strypstein S, Claeys S, Smet B, Pattyn P. Forgotten pathogen: Tetanus after gastrointestinal surgery. BMJ Case Reports 2019; DOI: 10.1136/bcr-2019-229701.
13. Mori M, Iida H, Miki K, et al. Postoperative tetanus after laparoscopic obturator hernia repair for strangulated ileus: Report of a case. Surgery Today 2012; 42:470–474. DOI: 10.1007/s00595-011-0023-6.

In addition, CT and MRI scans were non-contributory in supporting an infectious site or mechanism. However, as outlined in the paper, an X-ray of the hip showed a tiny focus of gas and soft tissues. As tetanus is a gas-forming organism, it is possible that the gas is secondary to infection, but the timing of the radiograph with respect to the surgery ultimately makes the gas indeterminate.

This is a presumptive healthcare associated infection, but the rarity of such an event and the absence of confirmation limit our ability to endorse changes to preoperative skin sterilization or other precautions during surgery.

Reviewer 3 Report

The authors in this case report study clearly demonstrates the medical conditions of the patient, enough background was provided to understand the clinical aspects in relation to the origin of the infection.

The study is very well written, easy to comprehend and provides an insight to the rare but complicated health condition like Tetanus. The patient was closely observed and screened for all the possible outcomes that could cause the problem.

The only one comment I can add is to 'provide evidence if they measured inflammatory response or any assay done to measure cytokines for the patient following infection'.

This study could possibly grab attention from the readers.

Author Response

We appreciate your interest and enthusiasm for our paper. Thank you for your detailed comments and inquiry.

The inflammatory response in our patient was supported by an elevation in the leukocyte count to 11,200 per cubic millimeter (normal range, 4,000 to 11,000), C-reactive protein to 220.5 mg/L (normal range, < 8), and Ferritin to 522 μg per liter (normal range, 15 to 200) [Lines 51-52 of the manuscript].

Cytokines were not measured.