An Unusual Manifestation of Q Fever: Peritonitis

Peritoneal dialysis-associated peritonitis caused by Coxiella Burnetii: A case report

RATIONALE

Peritoneal dialysis (PD)-associated peritonitis (PDAP) is the leading cause of PD failure and discontinuation of PD. Several zoonotic pathogens could lead to the development of PDAP. Coxiella burnetii (C. burnetii) was a zoonotic pathogen and the cause of Q fever. However, reports of PDAP caused by C. burnetii are rare. We herein report the first case of PDAP caused by C. burnetii in mainland China.

PATIENTS CONCERNS

A 45-year-old woman was admitted to our hospital with chief complaint of yellow and cloudy PD effluent for 2 days. She had undergone PD for 5 years due to end-stage renal disease. She was engaged in cattle and sheep breeding. The culture of PD effluent was negative, even for specific species, such as Mycobacteria and fungi.

DIAGNOSES

The culture from the PD effluent tested positive for C. burnetii by adopting metagenomic next-generation sequencing on day 37. We diagnosed her as PDAP caused by C. burnetii.

INTERVENTIONS

Empirical treatment with multiple broad-spectrum antibiotics (including vancomycin, etimicin, piperacillin) was initially adopted. After identifying C. burnetii as the culprint as the PDAP, the regimen was changed to doxycycline (100 mg twice daily) and moxifloxacin (400 mg once daily) orally, leading to clinical improvement.

OUTCOMES

The white blood cell count of the PD effluent decreased to within the normal range and the culture of PD effluent was negative for C. burnetii at the visit of 4 months after discharge. Also, there was no sign for recurrence.

LESSONS

Vigilance should be heightened for PDAP cases with negative culture of PD fluid and poor response to standard broad-spectrum antibiotic treatment, along with a history of cattle and sheep breeding. In such conditions, PD effluent should be tested to detect possible peritonitis caused by C. burnetii, even in patients without symptoms of fever. Prompt pathogen identification and appropriate treatment are crucial for clinical improvement of such cases.

Efficacy of rifapentine and other rifamycins against Coxiella burnetii in vitro

Since 1999, doxycycline and hydroxychloroquine have been the recommended treatment for chronic Q fever, a life-threatening disease caused by the bacterial pathogen, Coxiella burnetii. Despite the duration of its use, the treatment is not ideal due to the lengthy treatment time, high mortality rate, resistant strains, and the potential for contraindicated usage. A literature search was conducted to identify studies that screened large panels of drugs against C. burnetii to identify novel targets with potential efficacy against C. burnetii. Twelve candidate antimicrobials approved for use in humans by the US Food and Drug Administration were selected and minimum inhibitory concentrations (MICs) were determined against the low virulence strain Nine Mile phase II. Rifabutin and rifaximin were the best performing antibiotics tested with MICs of ≤0.01 µg mL-1. Further screening of these top candidates was conducted alongside two drugs from the same class, rifampin, well-characterized, and rifapentine, not previously reported against C. burnetii. These were screened against virulent strains of C. burnetii representing three clinically relevant genotypes. Rifapentine was the most effective in the human monocytic leukemia cell line, THP-1, with a MIC ≤0.01 µg mL-1. In the human kidney epithelial cell line, A-498, efficacy of rifapentine, rifampin, and rifabutin varied across C. burnetii strains with MICs between ≤0.001 and 0.01 µg mL-1. Rifampin, rifabutin, and rifapentine were all bactericidal against C. burnetii; however, rifabutin and rifapentine demonstrated impressive bactericidal activity as low as 0.1 µg mL-1 and should be further explored as alternative Q fever treatments given their efficacy in vitro.

IMPORTANCE

This work will help inform investigators and physicians about potential alternative antimicrobial therapies targeting the causative agent of Q fever, Coxiella burnetii. Chronic Q fever is difficult to treat, and alternative antimicrobials are needed. This manuscript explores the efficacy of rifamycin antibiotics against virulent strains of C. burnetii representing three clinically relevant genotypes in vitro. Importantly, this study determines the susceptibility of C. burnetii to rifapentine, which has not been previously reported. Evaluation of the bactericidal activity of the rifamycins reveals that rifabutin and rifapentine are bactericidal at low concentrations, which is unusual for antibiotics against C. burnetii.

… İlindeki Q ateşi olgularının retrospektif olarak değerlendirilmesi

Amaç: Q ateşi, özellikle risk grubundaki bireylerde akut ve kronik formda görülebilen, özgül olmayan semptomları nedeniyle tanısı atlanabilen, zoonotik bir hastalıktır. Önceleri sıklıkla yanlış tanı alan bu hastalık olguları, ülkemizden de son yıllarda bildirilmeye başlamıştır. Bu çalışmada Q ateşi olgularının klinik ve laboratuvar parametrelerini retrospektif olarak değerlendirmeyi ve Q ateşi farkındalığını arttırmayı amaçladık. Gereç ve Yöntem: Retrospektif gözlemsel çalışmamızda, 1 Ocak 2018–1 Mart 2021 tarihleri arasında hastanemizde takip ve tedavi edilen, 18 yaş üstü, kesin tanı almış, Q ateşi olguları değerlendirildi. Hastalara ait yaş, cinsiyet, meslek, ikamet edilen yer gibi demografik veriler, kene teması öyküleri, hastalığın geliştiği zaman dilimi (yıl, mevsim, ay), eşlik eden komorbiditeler, semptomlar, fizik muayene ve laboratuvar bulguları, tedaviler, hastaların iyileşme ve mortalite durumları irdelendi. Bulgular: Çalışmaya yaş ortalaması 49,23±12,07 yıl, 7’si (%57) erkek olan 14 olgu dahil edildi. Olguların sadece 5’i (%35,7) çiftçi, dördü (%28,57) hayvancılık yapıyordu. Kırsal alanda yaşama 9 (%64,28) olguda mevcuttu. En sık semptomlar ateş yüksekliği (%100), öksürük (%71,42) ve miyalji (%57,14) idi. Olguların tamamı akut Q ateşi olgusu olup, endokardit hiçbir olguda saptanmadı. Sonuç: Ülkemizin Q ateşi hastalığı için olası endemik bölgelerden olması nedeniyle, özellikle kırsal kesimde yaşayan, hayvancılıkla uğraşma, pastörize edilmemiş süt/süt ürünü tüketme gibi risk faktörleri olan hastalarda pnömoni başta olmak üzere birçok hastalığın ayırıcı tanısında düşünülmesi gerektiğini vurgulamak istedik.

Neurotransmitter System-Targeting Drugs Antagonize Growth of the Q Fever Agent, Coxiella burnetii, in Human Cells

Coxiella burnetii is a highly infectious, intracellular, Gram-negative bacterial pathogen that causes human Q fever, an acute flu-like illness that can progress to chronic endocarditis. C. burnetii is transmitted to humans via aerosols and has long been considered a potential biological warfare agent. Although antibiotics, such as doxycycline, effectively treat acute Q fever, a recently identified antibiotic-resistant strain demonstrates the ability of C. burnetii to resist traditional antimicrobials, and chronic disease is extremely difficult to treat with current options. These findings highlight the need for new Q fever therapeutics, and repurposed drugs that target eukaryotic functions to prevent bacterial replication are of increasing interest in infectious disease. To identify this class of anti-C. burnetii therapeutics, we screened a library of 727 FDA-approved or late-stage clinical trial compounds using a human macrophage-like cell model of infection. Eighty-eight compounds inhibited bacterial replication, including known antibiotics, antipsychotic or antidepressant treatments, antihistamines, and several additional compounds used to treat a variety of conditions. The majority of identified anti-C. burnetii compounds target host neurotransmitter system components. Serotoninergic, dopaminergic, and adrenergic components are among the most highly represented targets and potentially regulate macrophage activation, cytokine production, and autophagy. Overall, our screen identified multiple host-directed compounds that can be pursued for potential use as anti-C. burnetii drugs.

IMPORTANCECoxiella burnetii causes the debilitating disease Q fever in humans. This infection is difficult to treat with current antibiotics and can progress to long-term, potentially fatal infection in immunocompromised individuals or when treatment is delayed. Here, we identified many new potential treatment options in the form of drugs that are either FDA approved or have been used in late-stage clinical trials and target human neurotransmitter systems. These compounds are poised for future characterization as nontraditional anti-C. burnetii therapies.