Lyme borreliosis-from tick bite to diagnosis and treatment

Novel targets and strategies to combat borreliosis

Lyme borreliosis is a bacterial infection that can be spread to humans by infected ticks and may severely affect many organs and tissues. Nearly four decades have elapsed since the discovery of the disease agent called Borrelia burgdorferi. Although there is a plethora of knowledge on the infectious agent and thousands of scientific publications, an effective way on how to combat and prevent Lyme borreliosis has not been found yet. There is no vaccine for humans available, and only one active vaccine program in clinical development is currently running. A spirited search for possible disease interventions is of high public interest as surveillance data indicates that the number of cases of Lyme borreliosis is steadily increasing in Europe and North America. This review provides a condensed digest of the history of vaccine development up to new promising vaccine candidates and strategies that are targeted against Lyme borreliosis, including elements of the tick vector, the reservoir hosts, and the Borrelia pathogen itself.

Lyme Neuroborreliosis in a Patient with Breast Cancer: MRI and PET/CT Findings

We present a case demonstrating the performance of different radiographical and nuclear medicine imaging modalities in the diagnostic work-up of a patient with Lyme neuroborreliosis. The patient presented in late summer 2019 with radicular pains followed by a foot drop and peripheral facial palsy, both right-sided. Due to a history of breast cancer, disseminated malignant disease was initially suspected. Bone metastasis was ruled out by skeletal scintigraphy. Magnetic resonance imaging (MRI) of the neuroaxis and a whole body ¹⁸F-FDG PET-CT was performed within 48 hours. The MRI revealed a strong contrast enhancement of the conus medullaris and fibers of the cauda equina, while the ¹⁸F-FDG PET/CT was without pathological findings. Examination of cerebrospinal fluid led to the definitive diagnosis of Lyme neuroborreliosis with monocytic pleocytosis and a positive intrathecal test for Borrelia burgdorferi. The patient became pain-free after 10 days of ceftriaxone, and the paralysis slowly regressed the following month. This case highlights the difficulty of the diagnosis of Lyme neuroborreliosis and discusses the relevant imaging findings.

Diversity of Lyme borreliosis spirochetes isolated from ticks in Serbia

Spirochetes from the Borrelia burgdorferi sensu lato (s.l.). (Spirochaetales: Spirochaetaceae) species complex, including the causative agents of Lyme borreliosis, have been isolated from ticks, vertebrate reservoirs and humans. Previous analyses based on direct molecular detection in ticks indicated a considerable diversity of B. burgdorferi s.l. complex in Serbia. The present study aimed (a) to isolate borrelia strains from Serbia; (b) to determine their genotypic characteristics; and (c) to establish a collection of viable B. burgdorferi s.l. strains for further biological, ecological and genetic studies. For the present study, 231 adult Ixodes ricinus (Ixodida: Ixodidae) ticks from 16 ecologically different localities in Serbia were individually processed to cultivate B. burgdorferi s.l. This led to the isolation of 36 strains. A hbb gene quantitative real-time polymerase chain reaction (PCR) based on melting temperature determination and ospA gene sequencing were used to genotype the isolated spirochetes. The species identified based on the hbb gene real-time PCR were: Borrelia lusitaniae (44.4%), Borrelia afzelii (36.1%), Borrelia garinii (13.9%) and Borrelia valaisiana (5.6%), whereas the ospA sequence analysis revealed the occurrence of Borrelia bavariensis. This is the first report of the isolation of B. lusitaniae, B. garinii, B. bavariensis and B. valaisiana strains in Serbia.

Membrane directed expression in Escherichia coli of BBA57 and other virulence factors from the Lyme disease agent Borrelia burgdorferi

Membrane-embedded proteins are critical to the establishment, survival and persistence in the host of the Lyme disease bacterium Borrelia burgdorferi (Bb), but to date, there are no solved structures of transmembrane proteins representing these attractive therapeutic targets. All available structures from the genus Borrelia represent proteins expressed without a membrane-targeting signal peptide, thus avoiding conserved pathways that modify, fold and assemble membrane protein complexes. Towards elucidating structure and function of these critical proteins, we directed translocation of eleven expression-optimized Bb virulence factors, including the signal sequence, to the Escherichia coli membrane, of which five, BBA57, HtrA, BB0238, BB0323, and DipA, were expressed with C-terminal His-tags. P66 was also expressed using the PelB signal sequence fused to maltose binding protein. Membrane-associated BBA57 lipoprotein was solubilized by non-ionic and zwitterionic detergents. We show BBA57 translocation to the outer membrane, purification at a level sufficient for structural studies, and evidence for an α-helical multimer. Previous studies showed multiple critical roles of BBA57 in transmission, joint arthritis, carditis, weakening immune responses, and regulating other Bb outer surface proteins. In describing the first purification of membrane-translocated BBA57, this work will support subsequent studies that reveal the precise mechanisms of this important Lyme disease virulence factor.

Changing of the guard: How the Lyme disease spirochete subverts the host immune response

Lyme disease, also known as Lyme borreliosis, is the most common tick-transmitted disease in the Northern Hemisphere. The disease is caused by the bacterial spirochete Borrelia burgdorferi and other related Borrelia species. One of the many fascinating features of this unique pathogen is an elaborate system for antigenic variation, whereby the sequence of the surface-bound lipoprotein VlsE is continually modified through segmental gene conversion events. This perpetual changing of the guard allows the pathogen to remain one step ahead of the acquired immune response, enabling persistent infection. Accordingly, the vls locus is the most evolutionarily diverse genetic element in Lyme disease-causing borreliae. Small stretches of information are transferred from a series of silent cassettes in the vls locus to generate an expressed mosaic vlsE gene version that contains genetic information from several different silent cassettes, resulting in ∼10⁴⁰ possible vlsE sequences. Yet, despite its extreme evolutionary flexibility, the locus has rigidly conserved structural features. These include a telomeric location of the vlsE gene, an inverse orientation of vlsE and the silent cassettes, the presence of nearly perfect inverted repeats of ∼100 bp near the 5' end of vlsE, and an exceedingly high concentration of G runs in vlsE and the silent cassettes. We discuss the possible roles of these evolutionarily conserved features, highlight recent findings from several studies that have used next-generation DNA sequencing to unravel the switching process, and review advances in the development of a mini-vls system for genetic manipulation of the locus.

Potential Persistent Borrelia Infection and Response to Antibiotic Therapy; a Clinical Case Study and Review of Recent Literature

This report describes the case of an individual who was clinically diagnosed with Lyme borreliosis and initially responded to standard antibiotic therapy. Subsequent to treatment cessation, the patient experienced symptomatic rebound and failed to respond to a second course of the same antibiotic. The patient was eventually diagnosed with both Borrelia and Anaplasma infections by serological testing performed in a private laboratory. Following a two-month course of combination antibiotic therapy, the patient responded clinically, with a return to almost normal functioning. We discuss this case in the context of recent pre-clinical research examining potential Borrelial persistence despite antibiotic therapy.

Early Lyme Borreliosis in Patients Treated with Tumour Necrosis Factor-Alfa Inhibitors

The study evaluated the course and outcome of erythema migrans in patients receiving tumour necrosis factor-alpha (TNF-α) inhibitors. Among 4157 adults diagnosed with erythema migrans in the period 2009–2018, 16 (2.6%) patients were receiving TNF-α inhibitors (adalimumab, infliximab, etarnecept, golimumab), often in combination with other immunosuppressants, for rheumatic (13 patients) or inflammatory bowel (three patients) disease. Findings in this group were compared with those in 32 sex- and age-matched immunocompetent patients diagnosed with erythema migrans in the same years. In comparison with the control group, the immunocompromised patients had a shorter incubation period (7 vs. 14 days; p = 0.0153), smaller diameter of erythema migrans (10.5 vs. 15.5 cm; p = 0.0014), and more frequent comorbidities other than immune-mediated diseases (62.5% vs. 25%, p = 0.0269), symptoms/signs of disseminated Lyme borreliosis (18.8% vs. 0%, p = 0.0324), and treatment failure (25% vs. 0%, p = 0.0094). After retreatment with an antibiotic, the clinical course of Lyme borreliosis resolved. Continuing TNF inhibitor treatment during concomitant borrelial infection while using identical approaches for antibiotic treatment as in immunocompetent patients resulted in more frequent failure of erythema migrans treatment in patients receiving TNF inhibitors. However, the majority of treatment failures were mild, and the course and outcome of Lyme borreliosis after retreatment with antibiotics was favourable.

Antibiotic Use and Long-Term Outcome in Patients with Tick-Borne Encephalitis and Co-Infection with Borrelia Burgdorferi Sensu Lato in Central Europe. A Retrospective Cohort Study

In this retrospective cohort study of patients with tick-borne encephalitis (TBE), the clinical outcome in relation to co-infection with B. burgdorferi sensu lato (s.l.) and, specifically, the effect of antibiotic treatment on clinical outcome in patients with TBE who were seropositive for borreliae but who did not fulfil clinical or microbiologic criteria for proven co-infection, were assessed at a single university medical center in Slovenia, a country where TBE and Lyme borreliosis are endemic with high incidence. Among 684 patients enrolled during a seven-year period from 2007 through 2013, 382 (55.8%) had TBE alone, 62 (9.1%) had proven co-infection with borreliae and 240 (35.1%) had possible co-infection. The severity of acute illness was similar in all the groups. The odds for incomplete recovery decreased during a 12-month follow-up but were higher in women, older patients, and in those with more severe acute illness. Incomplete recovery was not associated with either proven (odds ratio (OR) 1.21, 95% confidence interval (CI) 0.49-2.95; p = 0.670) or possible co-infection (OR 0.95, 95% CI 0.55-1.65; p = 0.853). Among patients with possible co-infection, older patients were more likely to be prescribed antibiotics, but the odds for incomplete recovery were similar in those who received antibiotics and those who did not (OR 0.82, 95% CI 0.36-1.87; p = 0.630), suggesting that routine antibiotic treatment in patients with TBE and possible co-infection may not be warranted.

The RpoS Gatekeeper in Borrelia burgdorferi: An Invariant Regulatory Scheme That Promotes Spirochete Persistence in Reservoir Hosts and Niche Diversity

Maintenance of Borrelia burgdorferi within its enzootic cycle requires a complex regulatory pathway involving the alternative σ factors RpoN and RpoS and two ancillary trans-acting factors, BosR and Rrp2. Activation of this pathway occurs within ticks during the nymphal blood meal when RpoS, the effector σ factor, transcribes genes required for tick transmission and mammalian infection. RpoS also exerts a 'gatekeeper' function by repressing σ⁷⁰-dependent tick phase genes (e.g., ospA, lp6.6). Herein, we undertook a broad examination of RpoS functionality throughout the enzootic cycle, beginning with modeling to confirm that this alternative σ factor is a 'genuine' RpoS homolog. Using a novel dual color reporter system, we established at the single spirochete level that ospA is expressed in nymphal midguts throughout transmission and is not downregulated until spirochetes have been transmitted to a naïve host. Although it is well established that rpoS/RpoS is expressed throughout infection, its requirement for persistent infection has not been demonstrated. Plasmid retention studies using a trans-complemented ΔrpoS mutant demonstrated that (i) RpoS is required for maximal fitness throughout the mammalian phase and (ii) RpoS represses tick phase genes until spirochetes are acquired by a naïve vector. By transposon mutant screening, we established that bba34/oppA5, the only OppA oligopeptide-binding protein controlled by RpoS, is a bona fide persistence gene. Lastly, comparison of the strain 297 and B31 RpoS DMC regulons identified two cohorts of RpoS-regulated genes. The first consists of highly conserved syntenic genes that are similarly regulated by RpoS in both strains and likely required for maintenance of B. burgdorferi sensu stricto strains in the wild. The second includes RpoS-regulated plasmid-encoded variable surface lipoproteins ospC, dbpA and members of the ospE/ospF/elp, mlp, revA, and Pfam54 paralogous gene families, all of which have evolved via inter- and intra-strain recombination. Thus, while the RpoN/RpoS pathway regulates a 'core' group of orthologous genes, diversity within RpoS regulons of different strains could be an important determinant of reservoir host range as well as spirochete virulence.

Erythema Migrans: Course and Outcome in Patients Treated With Rituximab

Background

Information on Lyme borreliosis (LB) in patients treated with rituximab is limited to individual case reports.

Methods

We reviewed data on adult patients diagnosed with typical erythema migrans (EM) at the LB outpatient clinic of the University Medical Center Ljubljana, Slovenia, in the 10-year period 2008–2017. For all patients, clinical and laboratory information was acquired prospectively using a standardized questionnaire.

Results

Among 4230 adult patients with a diagnosis of EM, 7 patients (0.17%), 5 women and 2 men with a median age of 65 years (range, 55–66 years), were receiving rituximab for an underlying medical condition. In these 7 patients, signs of disseminated LB (43%) and the isolation rates of borreliae from blood before antibiotic treatment (40%) were unusually high compared with corresponding findings in immunocompetent patients who had EM diagnosed at the same institution (8% vs <2%, respectively). The rates of LB-associated constitutional symptoms and borrelial antibodies in serum were lower than expected (14% and 29%, respectively, in patients receiving rituximab vs 25% and 65% in immunocompetent patients). One of the 7 patients (14%) experienced treatment failure; nevertheless, the outcome of early LB 1 year after antibiotic treatment, as used for immunocompetent patients with EM, was excellent in all 7 patients.

Conclusions

Findings in 7 patients with EM who were receiving rituximab for underlying disease suggest that although early LB in these patients is more often disseminated than in immunocompetent patients, the outcome 1 year after antibiotic treatment, as used for immunocompetent patients, is excellent.

Borrelia burgdorferi peptidoglycan is a persistent antigen in patients with Lyme arthritis

Lyme disease, caused by the spirochete Borrelia burgdorferi, is the most common vector-borne disease in North America. If early infection is untreated, it can result in late-stage manifestations, including arthritis. Although antibiotics are generally effective at all stages of the disease, arthritis may persist in some patients for months to several years despite oral and intravenous antibiotic treatment. Excessive, dysregulated host immune responses are thought to play an important role in this outcome, but the underlying mechanisms are not completely understood. This study identifies the B. burgdorferi peptidoglycan, a major component of the cell wall, as an immunogen likely to contribute to inflammation during infection and in cases of postinfectious Lyme arthritis.

Lyme disease is a multisystem disorder caused by the spirochete Borrelia burgdorferi. A common late-stage complication of this disease is oligoarticular arthritis, often involving the knee. In ∼10% of cases, arthritis persists after appropriate antibiotic treatment, leading to a proliferative synovitis typical of chronic inflammatory arthritides. Here, we provide evidence that peptidoglycan (PG), a major component of the B. burgdorferi cell envelope, may contribute to the development and persistence of Lyme arthritis (LA). We show that B. burgdorferi has a chemically atypical PG (PG^Bb) that is not recycled during cell-wall turnover. Instead, this pathogen sheds PG^Bb fragments into its environment during growth. Patients with LA mount a specific immunoglobulin G response against PG^Bb, which is significantly higher in the synovial fluid than in the serum of the same patient. We also detect PG^Bb in 94% of synovial fluid samples (32 of 34) from patients with LA, many of whom had undergone oral and intravenous antibiotic treatment. These same synovial fluid samples contain proinflammatory cytokines, similar to those produced by human peripheral blood mononuclear cells stimulated with PG^Bb. In addition, systemic administration of PG^Bb in BALB/c mice elicits acute arthritis. Altogether, our study identifies PG^Bb as a likely contributor to inflammatory responses in LA. Persistence of this antigen in the joint may contribute to synovitis after antibiotics eradicate the pathogen. Furthermore, our finding that B. burgdorferi sheds immunogenic PG^Bb fragments during growth suggests a potential role for PG^Bb in the immunopathogenesis of other Lyme disease manifestations.

Borrelia burgdorferi (sensu lato) in ectoparasites and reptiles in southern Italy

BACKGROUND

Borrelia burgdorferi (sensu lato) is a complex containing pathogenic bacteria of which some species, such as Borrelia lusitaniae, use birds, small mammals and reptiles as reservoirs. In Italy, the bacteria have been detected in reptilian and avian reservoirs in the northern and central regions.

RESULTS

Here, 211 reptiles from three orders [Squamata (Sauria with seven species in five families and Ophidia with 11 species in three families), Crocodylia (one family and two species), and Testudines (two families and two species)] were examined for ectoparasites and molecular detection of B. burgdorferi (s.l.) in three different sites of southern Italy, an area for which no information was previously available on the occurrence of borreliosis in animals and humans. Borrelia lusitaniae was molecularly detected in larvae and nymphs (11.6%) of Ixodes ricinus infesting lizards (i.e. Podarcis muralis, Podarcis siculus and Lacerta bilineata) and in 12.3% blood samples of P. siculus. Finally, B. lusitaniae and Borrelia garinii were detected in 5.1% (32/630) of questing I. ricinus.

CONCLUSIONS

These results show the circulation of B. lusitaniae in southern Italy and suggest that P. siculus could play a role as a reservoir, representing a potential medical threat to humans living in or visiting these localities.

Acrodermatitis chronica atrophicans in children: Report on two cases and review of the literature

Acrodermatitis chronica atrophicans is a late manifestation of European Lyme borreliosis and is characterized by high levels of borrelial IgG antibodies, slowly expanding skin redness usually beginning on distal parts of extremities, and corresponding histologic findings. It very rarely develops in children. The main prerequisite for the diagnosis is clinical suspicion. In the present article we report on two children with acrodermatitis chronica atrophicans and on the findings of a PubMed literature search on acrodermatitis chronica atrophicans in childhood, published in the past three decades.