Third-degree atrioventricular block as a rare complication of disseminated gonococcal infection (DGI): A case report

Abstract

Third-degree atrioventricular (AV) block is characterised by complete dissociation between atrial and ventricular activity. It is commonly caused by degenerative conduction disease, ischaemia, medications, or in this case – an infective process. We report a rare case of third-degree AV block caused by disseminated gonococcal infection (DGI). Rates of Neisseria gonorrhoeae are increasing, and DGI remains an important but often under-recognised complication. While DGI typically presents with tenosynovitis, polyarthralgia, and skin lesions - cardiac involvement is uncommon. A 36-year-old cis-male who has sex with men presented with polyarthralgia, tenosynovitis, maculopapular rash, and exertional dyspnoea. Electrocardiogram (ECG) demonstrated third-degree AV block. Mucosal swabs were positive for N. gonorrhoeae at both rectal and pharyngeal sites, though blood cultures were likely negative due to prior antibiotic usage before obtaining cultures. Cardiac imaging showed no structural abnormality or evidence of endocarditis. In the absence of an alternative cause, a diagnosis of presumptive DGI was made. After treatment with intravenous ceftriaxone for seven days, cardiac conduction normalised. Follow-up ECG and cardiac magnetic resonance imaging (MRI) at later time points confirmed complete recovery. This case highlights a novel cardiac manifestation of DGI and reinforces the importance of recognising systemic complications of gonorrhoea.

Keywords

disseminated gonococcal infection third-degree atrioventricular block sexually transmitted infections

Background

Neisseria gonorrhoeae (N. gonorrhoeae) is one of the most common sexually transmitted infections in gay and bisexual men who have sex with men (GBMSM) with 71,802 new diagnoses in England reported in 2024 across all populations – a 16% decrease from 2023 but the second-highest annual total on record.¹ It is caused by a Gram-negative intracellular diplococcus that infects columnar epithelium-lined mucous membranes and spreads through sexual contact via mucous membranes. Haematogenous dissemination of gonococcal infection (DGI) may occur causing skin lesions, arthralgia, arthritis, and tenosynovitis. Cardiac manifestations are rare.²

Presentation

A 36-year-old cis-male who has sex with men presented in April 2024 with a four week history of tenosynovitis and migratory polyarthralgia with maculopapular rash over his arms and torso. He reported a ten day history of progressive exertional dyspnoea and postural light-headedness without syncope. He was otherwise well. He was not taking any regular medication other than daily pre-exposure prophylaxis (PrEP) (tenofovir disoproxil/emtricitabine, TDF/F). There was no recreational or injecting drug use and no personal or known family history of cardiac disease. He had been diagnosed with N. gonorrhoeae infection, isolated from both rectal and pharyngeal swab, with culture confirming ceftriaxone susceptibility (MIC <0.016) in February 2024. He was treated with intramuscular injection of ceftriaxone (1 g) at that time (culture showed sensitivity) but did not reattend for a test of cure. He had anal sex with no condom use with multiple new casual partners.

Investigations

Examination demonstrated a low-grade fever (37.9°C), bradycardia (heart rate of 46 bpm) without any signs of end organ hypoperfusion. Skin lesions had resolved. There were no genitourinary symptoms and no signs of infective endocarditis.

A 12-lead electrocardiogram (ECG) demonstrated atrio-ventricular dissociation, with narrow (QRS duration 90 msec) ventricular escape rhythm of 45–50 bpm; consistent with third-degree atrioventricular (AV) block (Figure 1). He was referred to the cardiology team for joint management.

Figure 1.

12-lead ECG showing third-degree heart block with atrioventricular dissociation: atrial rate (93 bpm), ventricular rate (45 bpm), QRS duration (90 ms).

A full sexual health screen was performed: first-void urine, pharyngeal and rectal swab were sent for nucleic acid amplification testing for Chlamydia trachomatis and Neisseria gonorrhoeae (Cepheid CT/GC Xpert®, Cepheid Diagnostics, US). Rectal and pharyngeal samples were again positive for N. gonorrhoeae and subsequent cultures showed susceptibility to ceftriaxone. Peripheral blood cultures were negative however the patient had completed a seven day course of flucloxacillin in the weeks prior to his presentation for skin lesions via another healthcare provider. Further investigations including HIV, syphilis testing, autoimmune screen, Lyme serology, and rheumatology screen were negative.

Transthoracic echocardiogram (TTE) showed no evidence of vegetation or aortic root abscess, mild biventricular dilatation with preserved function and normal structure and function of all valves and atria. Computed tomography (CT) aortogram demonstrated no evidence of aortitis. Cardiac magnetic resonance imaging (MRI) reported a small region of apical myocardial oedema, no overt features of scar and mild biventricular dilatation with preserved function.

Treatment

Initial treatment was commenced with IM ceftriaxone 1 g as per guidelines.² Gonorrhoea cultures showed ceftriaxone susceptibility (mean inhibitory concentration (MIC) <0.016). When DGI was suspected, treatment was optimised to a seven day course of IV ceftriaxone. The patient was offered dual chamber pacemaker insertion but opted for conservative management in the first instance. Symptoms gradually resolved and over a period of seven days the third-degree AV heart block progressively normalised. Follow-up 48-h 12-lead ECG at six-weeks post-treatment confirmed resolution of the conduction disease with sinus rhythm throughout (Figure 2). Cardiac rest gated positron emission tomography (PET) using fluorodeoxyglucose (FDG) a month after treatment demonstrated resolution of the myocardial oedema visualised on cardiac MRI, no FDG avid infection and no active myocarditis or large vessel vasculitis. Test of cure at affected sites were also negative. The patient remains well.

Figure 2.

12-lead ECG showing resolution of third-degree heart block following antimicrobial treatment with normal sinus rhythm noted.

Discussion

This case describes a previously unreported cardiac manifestation of presumptive DGI infection with the development of third-degree AV block without evidence of endocarditis with complete resolution following appropriate antimicrobial therapy.³ Blood cultures are negative in approximately 50% of cases of DGI,⁴ and prior antibiotic exposure may reduce culture sensitivity.

The multidisciplinary team concluded that AV block was most consistent with infectious aetiology ssupported by extensive negative investigations for alternative causes and full resolution of the conduction abnormalities after treatment for DGI. Cardiac involvement in DGI has been described; a case of acute myopericarditis⁵ has been reported and gonococcal endocarditis is estimated to occur in 1–2% of those with DGI.^6,7 Third-degree AV heart block associated with the development of aortitis in the context of gonococcal endocarditis⁸ has been reported. In younger populations, infection is an important cause of AV block with recognised infectious agents, notably Borrelia burgdorferi, associated with AV conduction abnormalities.⁹ However, third-degree AV block without evidence of infective endocarditis has not previously been reported.

Prevalence of N. gonorrhoeae remains high in the UK with 71,802 new diagnoses reported in 2024.¹ Only a small proportion (approximately 0.5–3%¹⁰) develop DGI (though likely underreported).¹¹ With rollout of the four-component meningococcal serogroup B vaccine (4CMenB) programme,¹² a reduction of gonorrhoea incidence may follow. Clinicians should remain vigilant for cardiac complications in patients presenting with gonorrhoea infection as early recognition may be lifesaving.

CPD Questions:

(1) What electrocardiographic feature defines third-degree atrioventricular block?

(Answer) Complete atrioventricular dissociation with independent atrial and ventricular rates.

(2) What are the common clinical manifestations of disseminated gonococcal infection (DGI)?

(Answer) Clinical manifestations may include: skin lesions, arthralgia, arthritis, and tenosynovitis. Cardiac manifestations are rare.

(3) What antibiotic is first-line for the treatment of DGI?

(Answer) As per BASHH guidelines, first-line antibiotic treatment is with ceftriaxone 1 gram either intravenously or by intramuscular injection every 24 hours.

(4) Why are blood cultures often negative in cases of DGI?

(Answer) Blood cultures are often negative due to intermittent bacteraemia and/or prior antibiotic exposure.

Footnotes

ORCID iD

Jonathan Joseph Goodfellow

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Declaration of conflicting interesting

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

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