Coinfection with “Rickettsia sibirica subsp. mongolotimonae” and Rickettsia conorii in a Human Patient: a Challenge for Molecular Diagnosis Tools

Abstract

Rickettsioses are zoonoses transmitted by vectors. More than one agent can coexist in vectors. Although vectors may transmit more than one microorganism to humans, information on dual infections is scarce. We present a case of a patient with an atypical rickettsiosis diagnosis in whom two species of Rickettsia were detected. CASE REPORTA 46-year-old woman was admitted to Bellvitge University Hospital in May with fever (38°C) as well as a retroauricular adenopathy and a subsequent preauricular and lateral cervical adenopathy that had lasted for 10 days. On examination at admission, she was afebrile and she had a necrotic eschar on the scalp (tache noire), face swelling, and a rash on her upper extremities. Laboratory examination showed normal values, except for the presence of activated lymphocytes and increased levels of alanine aminotransferase/aspartate aminotransferase, lactate dehydrogenase, and gamma-glutamyl transpeptidase. Testing of the patient's serum for toxoplasma and cytomegalovirus were negative. She reported that she had a dog and she had observed ticks on it recently.Tick-borne lymphadenopathy (TIBOLA) (recently called scalp eschar and neck lymphadenopathy syndrome [SENLAT]) caused by Rickettsia slovaca was suspected. As a consequence, a regimen of doxycycline (100 mg every 12 h for 4 days) was prescribed. The patient's condition improved. She was discharged 5 days after admission. The patient underwent periodical clinical evaluations for 49 days until her symptoms resolved completely.At admission, an acute-phase serum sample, a blood sample, and a scalp eschar biopsy specimen were collected. Serum was evaluated by indirect immunofluorescence assay (IFA).Antibodies against Rickettsia conorii were tested for using a commercial antigen (R. conorii spot; bioMérieux, Marcy l'Étoile, France). Antibodies against R. slovaca were tested for using an R. slovaca antigen kindly provided by the Unité de Rickettsies, Marseille, France. IgG antibodies against R. conorii antigen (titer Ͼ 5,120) were detected, whereas the IFA using R. slovaca antigen was negative. As neither clinical nor epidemiological variables were typical of Mediterranean spotted fever (MSF, whose etiological agent is R. conorii), and IFA for R. slovaca was not positive, a more accurate diagnosis was carried out.DNA was obtained from the whole-blood sample, the scalp eschar biopsy specimen, and the liquid that contained the scalp eschar biopsy specimen. For this purpose, the MasterPure DNA purification kit (Epicentre, Madison, WI) was used. PCR assays targeting the rickettsial genes for the citrate synthase (gltA) and the outer membrane protein A (ompA), were performed (Table 1). For the citrate synthase gene (gltA), primer CS890r and a new primer (CS214_for), designed by our team, were used. For the ompA gene, a real-time PCR was designed by our team using a new pair of primers: Rr190.314 and Rr190.630. In addition, another pair of primers was used (Rr190.70 and Rr190.701). This set of primers amplifies a bigger fragment that includes the on...

Prevalence of Rickettsia spp. in Ticks and Serological and Clinical Outcomes in Tick-Bitten Individuals in Sweden and on the Åland Islands

“…The latter may be of importance in explaining why participants with a recent or current co-infection with Borrelia spp. and Rickettsia spp., based on seroconversion, were fewer in the present study compared to findings from earlier studies where co-infection was based on sero-reactivity [18, 20]. …”

A proof of concept for a targeted enrichment approach to the simultaneous detection and characterization of rickettsial pathogens from clinical specimens

“…Due to overlapping areas of endemicity and shared vectors, rickettsial co-infection has been observed although it is rare, and it poses a potential challenge for molecular diagnostics ( Nogueras et al, 2015 ; Abreu et al, 2019 ; Kim et al, 2019 ). Therefore, replicate samples containing target genetic material at 12 gc/mL, the LoD of the existing qPCR assay for O. tsutsugamushi in the presence of R. prowazekii, were created in a background of human gDNA to simulate co-infected samples (and a control sample containing 0 gc/mL of O. tsutsugamushi gDNA was also included).…”

Case Report: Typhoid Fever and Spotted Fever Group Rickettsiosis Presenting Concomitantly in an Indian Immigrant

“…Physicians typically try to ascribe all symptoms and signs to a single diagnosis, but dual infections occasionally occur. They are typically found among patients with acquired immunodeficiency syndrome, 7 in cases in which the same vector transmits more than one pathogen, [8][9][10] or in food-poisoning outbreaks associated with more than one pathogen. [11][12][13] Apart from these situations, mixed infections acquired through different modes of transmissions probably exist (mainly in developing countries) but are under-diagnosed and hence underreported.…”