A Rare Case of Campylobacter rectus Pyogenic Extensor Tenosynovitis

Abstract

Introduction: Pyogenic extensor tenosynovitis is a severe inflammatory process of the extensor compartment of the hand. Common pathogens involved in this condition are Streptococcus and Staphylococcus; however, in immunocompromised patients, rare pathogens can be implicated. Case Report: Herein a rare case of a 61-year-old female who developed severe extensor tenosynovitis from Campylobacter rectus after a dog bite is presented. The patient required surgical debridement, four weeks of doxycycline and amoxicillin-clavulanate antibiotic therapy and physical therapy to successfully cure her C. rectus infection and preserve functionality. Conclusions: This case reinforces the virulence of microaerophilic pathogens, the need for multidisciplinary management in complex cases and alternative treatments with morbid obesity. As well, this case adds to the paucity of data with respect to this pathogen causing infections outside periodontal disease.

Introduction

Pyogenic extensor tenosynovitis (PET) is a severe inflammatory process of the extensor tendons located in the dorsal aspect of the hand [1]. The most common risk factors for PET are penetrating trauma and intravenous drug use and therefore, Staphylococcus and Streptococcus are typically the most common pathogens [1]. Unlike pyogenic flexor tenosynovitis which is well reported in medical literature, PET is seldom reported in the medical literature and, when reported, cases are usually from unusual microbes in immunocompromised hosts [1,2]. In flexor tenosynovitis there is heightened risk of tendon rupture secondary to raised pressures in the confined tendon sheaths which, if not relieved, causes necrosis and subsequent rupture leading to significant morbidity [2]. However, in the extensor compartment less defined tendon sheaths are present and subsequently tendon rupture risks are lower but inadequate treatments can still lead to tendon rupture and significant debility [1,2]. Consequently, management of PET requires multidisciplinary approaches with aggressive antimicrobial therapeutics, surgical debridement and physical therapy. Herein the successful treatment of a rare case of Campylobacter rectus PET of the hand is presented.

Case report

A 61-year-old female presented to an urgent care 24 hours after a canine bite with worsening pain and swelling of her hand. Her past medical history was significant for morbid obesity (BMI 54 kg/m²), bipolar disorder and psoriatic arthritis treated with methotrexate for the past 3 years. At the urgent care she was given oral amoxicillin-clavulanate 875 mg-125 mg twice a day but after 48 hours the swelling and pain intensified prompting her to go to the emergency room where severe swelling, erythema and limited range of motion of her left hand were observed. In the emergency room she was febrile to 38.6 °Celsius, tachycardic to 128 beats per minute and had a leukocytosis of 15,800 cells/µL (89% neutrophils). C-reactive protein was 13.1 mg/dL and erythrocyte sedimentation rate was 104 mm/h. Given the severity, the patient was admitted, and a CT of the left upper extremity showed extensive soft tissue inflammation of the dorsum of the hand, but no abscesses were seen (Figure 1). Intravenous vancomycin 2 grams every 12 hours and ampicillin-sulbactam 3 grams every 6 hours were initiated and an urgent hand surgical consultation was obtained after which surgical intervention was promptly conducted.

In the operating room, frank purulence tracked from the phalanges to the proximal metacarpal heads and severe inflammation was seen along the dorsal extensor tendon requiring a limited extensor tenosynovectomy of the middle finger. No purulence was observed beyond the metacarpal heads and numerous aerobic and anaerobic cultures were obtained from the debridement. The patient tolerated the surgery with no complications and vancomycin plus ampicillin-sulbactam were continued for 3 more days. By day four the patient’s fever, tachycardia and leukocytosis had resolved and her swelling and pain were slowly improving. However, no bacterial growth was observed on aerobic or anaerobic cultures by day four, but given her improvement she was discharged on oral sulfamethoxazole-trimethoprim DS twice a day and oral amoxicillin-clavulanate 875-125 mg twice a day. One day after discharge the anaerobic cultures grew C. rectus which prompted change from sulfamethoxazole-trimethoprim to oral doxycycline 100 mg twice a day. Fluoroquinolones were not used given the patient had prolonged QTc on electrocardiogram. To conduct antimicrobial sensitivity testing, her C. rectus isolate was sent to Associated Regional and University Pathologists Inc. (ARUP), a specialty lab providing national research laboratory services. ARUP performed sensitivity testing on the bacterial isolate using microbroth dilution (

Table 1. C. rectus susceptibility results.

Antibiotic	MIC μg/mL*
Ampicillin/sulbactam	≤0.25/0.12
Clindamycin	≤0.25
Meropenem	≤0.03
Metronidazole	≤0.25
Moxifloxacin	≤0.12
Penicillin	≤0.5
Piperacillin/tazobactam	≤1/4

MIC – minimum inhibitory concentration. *No standardized clinical and laboratory standards institute guidelines are available for this bacterium with respect to antimicrobial sensitivity testing.

). The patient tolerated these oral antibiotics for four weeks and slow improvements in swelling, erythema and range of motion were observed. After four weeks of antibiotic therapy, no further evidence of infection was observed clinically and antibiotics were then stopped but physical therapy was continued. Six months later the patient had no evidence of recurrence and had recovered mobility of her hand.

Discussion

C. rectus is a motile gram-negative rod. It is commonly found in the oral cavity of humans and is implicated in human and canine chronic periodontitis [3,4]. However, given its microaerophilic propensity, this bacterium is arduous to culture with standard microbiological techniques and is usually isolated in addition to other oral flora [3,4]. Consequently, there is a paucity of C. rectus cases documented outside the oral cavity and when isolated outside the oropharynx it is usually in the setting of polymicrobial infections [3,5]. This case report is unique in that only C. rectus was isolated from anaerobic bacterial cultures and was the causative pathogen in PET which is exceedingly rare.

Given the rarity of this bacterium to cause infections outside the oral cavity there is a paucity of knowledge on the proper treatment and duration of C. rectus extra-oral infections [3,5]. Confounding this is the fact that this bacterium is microaerophilic and therefore culturing this bacterium can be difficult and no standardized minimal inhibitory concentrations (MIC) exist for this pathogen. Therefore, this clinical isolate was sent to a reference lab to test for MIC to various antimicrobial agents (Table 1). Very low MICs to all agents tested were observed and no beta-lactamase was present. This is contrary to other Campylobacter species where resistance can be common [6]. In addition, this pathogen is usually associated with polymicrobial infections where beta-lactamases can be common [6]. This reinforces that for C. rectus infections the use of beta-lactam antibiotics without a beta-lactamase inhibitor should be avoided.

In this case the patient’s clinical isolate had no observable resistance and she was treated with amoxicillin-clavulanate and doxycycline for 4 weeks. Antibiotics were selected for sensitivity testing based on potential alternative oral agents (metronidazole, moxifloxacin and clindamycin) as well as possible intravenous agents if her condition did not improve (ampicillin-sulbactam, meropenem and piperacillin-tazobactam). Lastly, penicillin was chosen to evaluate if a beta-lactamase was present. Despite the limited resistance seen on sensitivity testing, dual agents were used given the patient’s body habitus (BMI 54), concern for compliance with three times a day dosing and given baseline QTc over 500 preventing fluoroquinolone use. Sulfamethoxazole-trimethoprim is known to have varying resistance in Campylobacter species and therefore this was not used in this case [7]. While amoxicillin-clavulanate had potential good in vitro sensitivity to the patient’s isolate, her morbid obesity predisposed her to not achieving adequate therapeutic levels with twice a day dosing and therefore three times a day dosing was recommended which the patient did not think she would be compliant with [8]. Consequently, doxycycline was used given dose altering in morbid obese patients is not recommended for this antibiotic [9]. However, doxycycline therapy is not commonly used for C. rectus infections, but it has been successfully used for other campylobacteria infections [10]. The reference lab was asked to test for tetracycline sensitivity but declined to conduct this testing. Nonetheless, the combined therapy led to a successful cure of the infection, but the dual therapy clouds the effectiveness of doxycycline itself. Overall, the sensitivity testing displayed here adds to the paucity of antibiotic sensitivity data on this pathogen.

The use of methotrexate for her underlying psoriatic arthritis caused her to have reduced cell-mediated and humoral immunity [11]. As a result, the patient was treated for four weeks given the severity of her hand infection and underlying immunosuppression. Slow improvements were seen with respect to swelling and erythema, likely in part from her reduced immune response and from the slow growth of the pathogen itself. While antibiotics were part of her treatment, as seen with the lack of improvement with oral amoxicillin-clavulanate, source control with surgical debridement was paramount to debulk the infection burden and therefore allow antibiotics and her immune system the chance to cure the infection before irreversible damage was done. Physical therapy was also important to prevent contractures. This reinforces the need for multidisciplinary approaches in severe complex cases to achieve effective outcomes and prevent long lasting debility.

Conclusions

In conclusion, this report presents a rare case of a severe pyogenic extensor tenosynovitis caused by C. rectus after a canine bite. While this is a rare infection, C. rectus may be underreported in polymicrobial anaerobic infections, especially when infections are associated with poor oral hygiene. This case adds to the limited literature published with respect to this pathogen causing infections outside periodontal disease and supports the need to be cognizant of therapy adjustments needed for morbidly obese patients.