Endocarditis due to Bartonella quintana, the etiological agent of trench fever

• Bartonella quintana, the causal agent of trench fever, is transmitted by body lice (Pediculus humanus var. corporis).

• Although B. quintana is notorious for causing disease in the First World War, outbreaks of trench fever have recently occurred in urban populations experiencing homelessness.

• B. quintana causes culture-negative endocarditis and may be fatal without antimicrobial and surgical treatment, despite mild symptomatology during chronic bacteremia. Consultation with infectious disease specialists is encouraged.

• Because B. quintana evades identification in routine blood cultures, diagnosis of B. quintana requires serology and explicit communication with the microbiology laboratory to incorporate measures to specifically recover B. quintana and to arrange molecular testing.

A 48-year-old man presented to the emergency department with a 2-day history of pleuritic chest pain and shortness of breath. His medical history included HIV infection, diagnosed 14 years earlier in the context of intravenous drug use. Three months previously, he had an undetectable viral load and a CD4 count of 94 cells/mm³ (normal range: 500–1400 cells/mm³) or 0.09 (normal range 0.50–1.40) × 10⁹/L. The patient adhered to his prescribed antiretroviral regimen (darunavir, ritonavir and abacavir-lamivudine) and prophylaxis against opportunistic infections (valacyclovir, trimethoprim-sulfamethoxazole and fluconazole). In addition, the patient had a congenital solitary kidney with normal baseline renal function, alcohol exposure in utero and alcohol use disorder. He had stopped injecting drugs many years earlier. On several occasions over the past 18 months, the patient had sought care for episodes of chest pain and body lice infestation. Although the patient lived in supportive housing at the time of presentation, he had lived in a homeless shelter less than a year earlier.

On presentation, the patient’s temperature was 36.7°C, blood pressure was 106/65 mm Hg, pulse was 83 beats/min, respiratory rate was 60 breaths/min and oxygen saturation was 100% on 15 L/min of oxygen. On auscultation, he had a holosystolic murmur and an early diastolic decrescendo murmur. Examination of the patient’s skin showed hemorrhagic puncta and scabs from arthropod bites (Figure 1). There were no peripheral manifestations of endocarditis.

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Figure 1:

Hemorrhagic punctate lesions and scabs from ectoparasitosis on a 48-year-old man with endocarditis due to Bartonella quintana (patient 1). Note that, unlike bedbugs, the lesions do not follow areas of pressure such as belt or sock lines.

Computed tomography of the chest and abdomen showed pulmonary emboli, splenic infarcts, splenomegaly and aneurysms of the abdominal aortic branches. A bedside echocardiogram showed severe mitral regurgitation and a large echogenic mitral vegetation. Two sets of blood samples were drawn for cultures before empiric administration of piperacillin-tazobactam and vancomycin for presumptive endocarditis.

The patient’s initial tachypnea improved with pain control and his supplemental oxygen was weaned to 2 L/min. However, 10 hours after presentation, the patient became acutely tachypneic and hypoxemic, requiring 15 L/min oxygen to maintain normal saturation. Because of his worsening respiratory distress, we started mechanical ventilation and transferred him to the intensive care unit. A transesophageal echocardiogram showed severe mitral regurgitation with a 25 × 9 mm vegetation on the mitral valve and severe aortic regurgitation associated with multiple smaller vegetations.

Four days after admission, our patient underwent mitral and aortic valve replacement surgery for severe valvular damage. Pathology results showed 4+ polymorphonuclear cells in the tissue of both valves; no organisms were seen on Gram staining, and no pathogen growth was detected on aerobic, anaerobic and fungal cultures. Four blood samples, 2 drawn before antibiotic administration, were culture-negative after 5 days of incubation. We were not able to culture any organism despite lysis centrifugation and prolonged incubation of 6 weeks. We obtained serologies for Bartonella quintana, Bartonella henselae, Coxiella burnetii and Brucella species as recommended when there is concern for culture-negative endocarditis. Serologies for both Bartonella quintana and Bartonella henselae showed immunoglobulin G titres greater than 1:8192 (normal range < 1:64),1 while those for Coxiella and Brucella were negative. Results from 16S rRNA sequencing from both valves showed Bartonella quintana genetic material with 100% homology over 741 base pairs.

Nine days after admission, we changed the antimicrobial therapy to doxycycline and gentamicin. Because of worsening renal failure, we changed gentamicin to ceftriaxone after 4 days. Ceftriaxone and doxycycline were continued for 6 weeks after surgery. Two weeks after valve replacement, the patient was discharged from hospital and completed treatment as an outpatient. He remained well at follow-up 3 months after discharge.

Three additional patients with B. quintana were identified in Winnipeg over a 6-month period, all of whom had accessed resources at the same homeless shelter (details in Appendix 1 and Appendix 2, available at www.cmaj.ca/lookup/doi/10.1503/cmaj.201170/tab-related-content). A summary of all 4 cases is presented in Box 1.