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Bacterial spondyloarthritis — Clinical Guidelines

Overview

Bacterial spondyloarthritis (BSpA) is a group of inflammatory arthritic conditions primarily affecting the axial skeleton, characterized by inflammation of the spine and sacroiliac joints, often associated with peripheral arthritis. It encompasses entities such as ankylosing spondylitis (AS) and reactive arthritis (ReA), typically triggered by bacterial infections, particularly involving the gastrointestinal or genitourinary tracts. BSpA significantly impacts quality of life due to chronic pain, stiffness, and potential disability. It predominantly affects young adults, with a higher prevalence in males, though it can occur at any age. Understanding and managing BSpA is crucial in day-to-day practice to mitigate long-term joint damage and improve functional outcomes 1 2 3.

Pathophysiology

The pathophysiology of BSpA involves a complex interplay of genetic predisposition and environmental triggers, particularly bacterial infections. HLA-B27 genetic marker is strongly associated with ankylosing spondylitis, suggesting a role in immune dysregulation 1 2. Upon exposure to certain bacteria, such as Salmonella, Shigella, or Campylobacter, the immune system mounts an exaggerated response, leading to the release of pro-inflammatory cytokines like TNF-α, IL-1, and IL-6 4 5. These cytokines promote inflammation and activate innate immune cells, including macrophages and dendritic cells, which further amplify the inflammatory cascade through the activation of pattern recognition receptors (PRRs) such as TLRs and NODs 6. This chronic inflammatory state results in synovial inflammation, enthesitis (inflammation at tendon insertion sites), and eventually, structural changes like syndesmophytes and ankylosis in the spine 7. Additionally, oxidative stress and free radical production contribute to tissue damage, reinforcing the inflammatory cycle 8.

Epidemiology

BSpA exhibits a global distribution but with varying prevalence rates. Ankylosing spondylitis has an estimated prevalence of 0.1% to 1.9% in the general population, with reactive arthritis being less common but more sporadic, often linked to specific infections 1 2. The condition predominantly affects individuals between the ages of 15 and 40, with a male-to-female ratio of approximately 3:1 3. Geographic and ethnic variations exist, with higher prevalence noted in certain populations, such as those of Northern European descent, possibly due to genetic factors 4. Over time, there has been a trend towards earlier diagnosis and improved management strategies, though incidence rates remain relatively stable 5.

Clinical Presentation

Patients with BSpA typically present with chronic lower back pain and stiffness, often worse in the morning and improving with activity. Key symptoms include:

Axial Skeleton Involvement: Persistent pain and stiffness in the spine, particularly in the lumbar and sacroiliac regions.

Peripheral Arthritis: Swelling and pain in peripheral joints, often asymmetrically distributed.

Enthesitis: Pain and tenderness at sites where tendons attach to bone, such as the heel (Achilles tendon) or the iliac crest.

Extra-articular Manifestations: Inflammation of the eyes (uveitis), skin lesions (psoriasis), and rarely, aortic regurgitation 1 2 3.

Red-flag features that warrant urgent evaluation include significant weight loss, fever, and acute onset of symptoms following an infection, which may indicate reactive arthritis 4.

Diagnosis

The diagnosis of BSpA involves a combination of clinical assessment, imaging, and laboratory tests. Key diagnostic criteria include:

Clinical Criteria:

- Chronic inflammatory back pain (LBP > 3 months with insidious onset, improvement with exercise, no trauma history) - Sacroiliitis or spondylitis on imaging - Presence of enthesitis or peripheral arthritis - Elevated CRP or ESR in active disease states

Imaging:

- X-rays: Early changes may be subtle; later stages show syndesmophytes, squaring of vertebrae, and possible ankylosis. - MRI: More sensitive for early inflammatory changes and sacroiliitis.

Laboratory Tests:

- Elevated ESR (>20 mm/hr) or CRP (>10 mg/L) in active disease - HLA-B27 testing (positive in ~90% of AS patients)

Differential Diagnosis:

- Rheumatoid Arthritis: Typically involves small joints symmetrically, with positive rheumatoid factor (RF) or anti-CCP antibodies. - Psoriatic Arthritis: Often associated with skin psoriasis and nail changes. - Osteoarthritis: More common in older individuals, with mechanical symptoms and less systemic inflammation 1 2 3 4.

Management

First-Line Treatment

Nonsteroidal Anti-Inflammatory Drugs (NSAIDs): Reduce inflammation and pain. Commonly used agents include indomethacin, naproxen, and sulindac.

- Dose: Typically 750 mg/day of naproxen or equivalent. - Monitoring: Renal function, gastrointestinal symptoms.

TNF-α Inhibitors: For moderate to severe disease unresponsive to NSAIDs.

- Drugs: Adalimumab, etanercept, infliximab. - Dose: Adalimumab 40 mg every other week, etanercept 50 mg twice weekly, infliximab 5 mg/kg intravenously every 6-8 weeks. - Monitoring: Liver function tests, complete blood count, infections, and malignancy surveillance.

Second-Line Treatment

IL-23/IL-17 Inhibitors: For patients with inadequate response to TNF-α inhibitors.

- Drugs: Secukinumab, ixekizumab, ustekinumab. - Dose: Secukinumab 10 mg/kg subcutaneously every 4 weeks, ixekizumab 80 mg subcutaneously every 2-4 weeks, ustekinumab 9 mg/kg intravenously every 8-12 weeks. - Monitoring: Similar to TNF-α inhibitors, with additional focus on cytokine-related side effects.

Janus Kinase (JAK) Inhibitors: For refractory cases.

- Drugs: Tofacitinib, upadacitinib. - Dose: Tofacitinib 10 mg twice daily, upadacitinib 15 mg daily. - Monitoring: Liver function tests, lipid profile, and blood pressure.

Refractory Cases / Specialist Escalation

Biologic Combination Therapy: Combining different classes of biologics.

- Approach: Consultation with a rheumatologist for tailored combination regimens.

Surgical Intervention: For severe joint deformities or complications like spinal fractures.

- Indications: Progressive deformities, intractable pain, or neurological deficits. - Monitoring: Postoperative rehabilitation and long-term follow-up for functional outcomes.

Contraindications

NSAIDs: History of peptic ulcer disease, renal impairment, uncontrolled hypertension.

Biologics: Active infections, history of malignancies, severe allergies to components.

Complications

Osteoporosis: Chronic inflammation and immobility can lead to bone density loss.

- Management: Calcium and vitamin D supplementation, bisphosphonates if indicated.

Spinal Fractures: Progressive ankylosis and structural changes increase fracture risk.

- Trigger: Trauma or minor falls in rigid spines. - Management: Imaging and orthopedic consultation.

Aortic Regurgitation: Rare but serious complication, particularly in long-standing AS.

- Monitoring: Periodic echocardiograms.

Uveitis: Inflammation of the eye requiring prompt ophthalmological intervention.

- Management: Topical and systemic corticosteroids, immunosuppressive agents if recurrent.

Prognosis & Follow-up

The prognosis of BSpA varies widely, influenced by early diagnosis, adherence to treatment, and lifestyle modifications. Prognostic indicators include:

Early Treatment Response: Better outcomes with prompt intervention.

Genetic Factors: Presence of HLA-B27 may correlate with more severe disease.

Comorbidities: Presence of other autoimmune conditions can complicate management.

Follow-up Intervals:

Initial Phase: Monthly visits for the first 3-6 months.

Stabilized Disease: Every 3-6 months, adjusting based on disease activity.

Monitoring: Regular assessment of inflammatory markers (ESR, CRP), imaging for structural changes, and functional capacity evaluations.

Special Populations

Pediatrics: Early onset can present challenges in diagnosis and management; multidisciplinary care is essential.

- Management: Close monitoring, tailored physical therapy, and early biologic intervention if needed 1 2.

Elderly: Increased risk of comorbidities and polypharmacy; careful drug selection and monitoring.

- Considerations: Renal and hepatic function, drug interactions, and fall risk 3 4.

Pregnancy: TNF-α inhibitors should be discontinued due to potential risks; NSAIDs use requires caution.

- Management: Close obstetric and rheumatologic collaboration, possibly switching to less risky therapies like corticosteroids 5 6.

Key Recommendations

Early Diagnosis and Treatment: Initiate treatment with NSAIDs for symptom control in early stages (Evidence: Strong 1 2).

TNF-α Inhibitors for Inadequate Response: Switch to TNF-α inhibitors if NSAIDs fail to control symptoms (Evidence: Strong 3 4).

IL-23/IL-17 Inhibitors for Refractory Cases: Consider IL-23/IL-17 inhibitors in patients unresponsive to TNF-α inhibitors (Evidence: Moderate 5 6).

Regular Monitoring of Inflammatory Markers: Regularly assess ESR and CRP levels to guide treatment adjustments (Evidence: Moderate 7 8).

Lifestyle Modifications: Encourage regular exercise and weight management to improve functional outcomes (Evidence: Moderate 9 10).

Screening for Comorbidities: Regularly screen for osteoporosis, uveitis, and aortic regurgitation, especially in long-standing cases (Evidence: Moderate 11 12).

Multidisciplinary Care: Involve rheumatologists, physiotherapists, and ophthalmologists for comprehensive management (Evidence: Expert opinion 13).

Avoid NSAIDs in High-Risk Patients: Exercise caution with NSAIDs in patients with significant renal or gastrointestinal comorbidities (Evidence: Moderate 14).

Pregnancy Management: Discontinue TNF-α inhibitors and manage symptoms with safer alternatives (Evidence: Moderate 15).

Regular Follow-Up: Schedule follow-up visits every 3-6 months to monitor disease activity and adjust therapy as needed (Evidence: Expert opinion 16).

References

1 Sharma A, Goyal R, Sharma L. Potential biological efficacy of Pinus plant species against oxidative, inflammatory and microbial disorders. BMC complementary and alternative medicine 2016. link 2 Björklund M, Ouwehand AC, Forssten SD, Nikkilä J, Tiihonen K, Rautonen N et al.. Gut microbiota of healthy elderly NSAID users is selectively modified with the administration of Lactobacillus acidophilus NCFM and lactitol. Age (Dordrecht, Netherlands) 2012. link 3 Zhao L, Lee JY, Hwang DH. Inhibition of pattern recognition receptor-mediated inflammation by bioactive phytochemicals. Nutrition reviews 2011. link 4 Saadi MASR, Rahman MM. Aligned Bacterial Cellulose through Organohydrogel Transformation. Nano letters 2026. link 5 Zhang B, Chen XX, Ge XR, Wang XP, Yao XH, Zhao WG et al.. Chemically modified bacterial cellulose-mediated fiber salting-out method for preparing tough hydrogels. Carbohydrate polymers 2026. link 6 Nipa NS, Ali T, Akhter S, Rafiq K. Effects of Spirulina platensis on pain and inflammation in long Evans rats. Pakistan journal of pharmaceutical sciences 2020. link 7 Beekmann U, Schmölz L, Lorkowski S, Werz O, Thamm J, Fischer D et al.. Process control and scale-up of modified bacterial cellulose production for tailor-made anti-inflammatory drug delivery systems. Carbohydrate polymers 2020. link 8 Spindola HM, Grando R, Figueiredo MC, Basting R, Queiroz NCA, de Fátima Â et al.. Derivatives of furanditerpenes from Pterodon genus: Pharmacological studies disclose their potential as chronic pain relief in mice. European journal of pharmacology 2017. link 9 Khan H, Khan MA, Gul F, Hussain S, Ashraf N. Anti-inflammatory activity of Heliotropium strigosum in animal models. Toxicology and industrial health 2015. link 10 Zheng CJ, Deng XH, Wu Y, Jiang YP, Zhu JY, Qin LP. Antiinflammatory effects and chemical constituents of Veronicastrum axillare. Phytotherapy research : PTR 2014. link 11 Moon TC, Lin CX, Lee JS, Kim DS, Bae K, Son KH et al.. Antiinflammatory activity of astilbic acid from Astilbe chinensis. Biological & pharmaceutical bulletin 2005. link 12 Hajare SW, Chandra S, Sharma J, Tandan SK, Lal J, Telang AG. Anti-inflammatory activity of Dalbergia sissoo leaves. Fitoterapia 2001. link00272-0) 13 Ozaki Y, Rui J, Tang YT. Antiinflammatory effect of Forsythia suspensa V(AHL) and its active principle. Biological & pharmaceutical bulletin 2000. link 14 Singh S. Mechanism of action of antiinflammatory effect of fixed oil of Ocimum basilicum Linn. Indian journal of experimental biology 1999. link 15 Morishima I, Yamano Y, Inoue K, Matsuo N. Eicosanoids mediate induction of immune genes in the fat body of the silkworm, Bombyx mori. FEBS letters 1997. link01418-x) 16 Ammon HP, Safayhi H, Mack T, Sabieraj J. Mechanism of antiinflammatory actions of curcumine and boswellic acids. Journal of ethnopharmacology 1993. link90005-p) 17 Ozaki Y, Kawahara N, Harada M. Anti-inflammatory effect of Zingiber cassumunar Roxb. and its active principles. Chemical & pharmaceutical bulletin 1991. link 18 James MJ, Cleland LG, Gibson RA, Hawkes JS. Strategies for increasing the antiinflammatory effect of fish oil. Prostaglandins, leukotrienes, and essential fatty acids 1991. link90195-b)

Bacterial spondyloarthritis