Demonstration of intracellular microorganisms (Rickettsia spp., Chlamydia pneumoniae, Bartonella spp.) in pathological human aortic valves by PCR

Metals and Trace Elements in Calcified Valves in Patients with Acquired Severe Aortic Valve Stenosis: Is There a Connection with the Degeneration Process?

BACKGROUND

Acquired calcified aortic valve stenosis is the most common valve disease in adulthood. In the etiopathogenesis of this complex pathology, the importance of inflammation is mentioned, in which non-infectious influences represented by the biological effects of metal pollutants may participate. The main goal of the study was to determine the concentration of 21 metals and trace elements-aluminium (Al), barium (Ba), cadmium (Cd), calcium (Ca), chrome (Cr), cobalt (Co), copper (Cu), gold (Au), lead (Pb), magnesium (Mg), mercury (Hg), molybdenum (Mo), nickel (Ni), phosphorus (P), selenium (Se), strontium (Sr), sulfur (S), tin (Sn), titanium (Ti), vanadium (V) and zinc (Zn)-in the tissue of calcified aortic valves and to compare them with the concentrations of the same elements in the tissue of healthy aortic valves in the control group.

MATERIAL AND METHODS

The study group consisted of 49 patients (25 men, mean age: 74) with acquired, severe, calcified aortic valve stenosis with indicated heart surgery. The control group included 34 deceased (20 men, median age: 53) with no evidence of heart disease. Calcified valves were explanted during cardiac surgery and deep frozen. Similarly, the valves of the control group were removed. All valves were lyophilized and analyzed by inductively coupled plasma mass spectrometry. The concentrations of selected elements were compared by means of standard statistical methods.

RESULTS

Calcified aortic valves contained significantly higher (p < 0.05) concentrations of Ba, Ca, Co, Cr, Mg, P, Pb, Se, Sn, Sr and Zn and-in contrast-lower concentrations of Cd, Cu, Mo, S and V than valves of the control group. Significant positive correlations of concentrations between the pairs Ca-P, Cu-S and Se-S and strong negative correlations between the elements Mg-Se, P-S and Ca-S were found in the affected valves.

CONCLUSION

Aortic valve calcification is associated with increased tissue accumulation of the majority of the analyzed elements, including metal pollutants. Some exposure factors may increase their accumulation in the valve tissue. A relationship between exposure to environmental burden and the aortic valve calcification process cannot be ruled out. Advances in histochemical and imaging techniques allowing imaging of metal pollutants directly in valve tissue may represent an important future perspective.

Occurrence and Identification of Ixodes ricinus Borne Pathogens in Northeastern Italy

In Europe, Ixodes ricinus is the main vector for tick-borne pathogens (TBPs), the most common tick species in Italy, particularly represented in pre-alpine and hilly northern areas. From 2011 to 2017, ticks were collected by dragging in Belluno province (northeast Italy) and analyzed by molecular techniques for TBP detection. Several species of Rickettsia spp. and Borrelia spp. Anaplaspa phagocitophilum, Neoerlichia mikurensis and Babesia venatorum, were found to be circulating in the study area carried by I. ricinus (n = 2668, all stages). Overall, 39.1% of screened pools were positive for at least one TBP, with a prevalence of 12.25% and 29.2% in immature stages and adults, respectively. Pathogens were detected in 85% of the monitored municipalities, moreover the presence of TBPs varied from one to seven different pathogens in the same year. The annual TBPs prevalence fluctuations observed in each municipality highlights the necessity of performing continuous tick surveillance. In conclusion, the observation of TBPs in ticks remains an efficient strategy for monitoring the circulation of tick-borne diseases (TBDs) in a specific area.

Investigation of Tick-Borne Pathogens in Ixodes ricinus in a Peri-Urban Park in Lombardy (Italy) Reveals the Presence of Emerging Pathogens

Ticks are important vectors of a great range of pathogens of medical and veterinary importance. Lately, the spread of known tick-borne pathogens has been expanding, and novel ones have been identified as (re)emerging health threats. Updating the current knowledge on tick-borne pathogens in areas where humans and animals can be easily exposed to ticks represents a starting point for epidemiological studies and public awareness. A PCR screening for tick-borne pathogens was carried out in Ixodes ricinus ticks collected in a peri-urban recreational park in Ticino Valley, Italy. The presence of Rickettsia spp., Borrelia burgdorferi senso latu complex, Anaplasma spp. and Babesia spp. was evaluated in a total of 415 I. ricinus specimens. Rickettsia spp. (R monacensis and R. helvetica) were detected in 22.96% of the samples, while B. burgdorferi s.l. complex (B. afzelii and B. lusitaniae) were present in 10.94%. Neoehrlichia mikurensis (1.99%) and Babesia venatorum (0.73%) were reported in the area of study for the first time. This study confirmed the presence of endemic tick-borne pathogens and highlighted the presence of emerging pathogens that should be monitored especially in relation to fragile patients, the difficult diagnosis of tick-borne associated diseases and possible interactions with other tick-borne pathogens.

Myocarditis in Mediterranean spotted fever: a case report and a review of the literature

INTRODUCTION

Mediterranean spotted fever (MSF) is a tick-borne acute febrile disease caused by Rickettsia conorii. Most cases follow a benign course, with a case fatality rate of 3-7 % among hospitalized patients. Complications are described mainly in adult patients and include hepatic, renal, neurological and cardiac impairment. Among cardiac complications, pericarditis, myocarditis and heart rhythm disorders are uncommon complications in MSF and only a few cases have been reported in the literature.

CASE PRESENTATION

We describe a new case of acute myocarditis complicating MSF in an immunocompetent adult patient without risk factors for severe MSF.

CONCLUSION

Myocarditis is an uncommon but severe complication of MSF. Clinicians should be aware of a possible cardiac involvement in patients with MSF. Close monitoring and an aggressive approach are essential to reduce mortality rates of MSF.

Absence of zoonotic Bartonella species in questing ticks: first detection of Bartonella clarridgeiae and Rickettsia felis in cat fleas in the Netherlands

Background

Awareness for flea- and tick-borne infections has grown in recent years and the range of microorganisms associated with these ectoparasites is rising. Bartonella henselae, the causative agent of Cat Scratch Disease, and other Bartonella species have been reported in fleas and ticks. The role of Ixodes ricinus ticks in the natural cycle of Bartonella spp. and the transmission of these bacteria to humans is unclear. Rickettsia spp. have also been reported from as well ticks as also from fleas. However, to date no flea-borne Rickettsia spp. were reported from the Netherlands. Here, the presence of Bartonellaceae and Rickettsiae in ectoparasites was investigated using molecular detection and identification on part of the gltA- and 16S rRNA-genes.

Results

The zoonotic Bartonella clarridgeiae and Rickettsia felis were detected for the first time in Dutch cat fleas. B. henselae was found in cat fleas and B. schoenbuchensis in ticks and keds feeding on deer. Two Bartonella species, previously identified in rodents, were found in wild mice and their fleas. However, none of these microorganisms were found in 1719 questing Ixodes ricinus ticks. Notably, the gltA gene amplified from DNA lysates of approximately 10% of the questing nymph and adult ticks was similar to that of an uncultured Bartonella-related species found in other hard tick species. The gltA gene of this Bartonella-related species was also detected in questing larvae for which a 16S rRNA gene PCR also tested positive for "Candidatus Midichloria mitochondrii". The gltA-gene of the Bartonella-related species found in I. ricinus may therefore be from this endosymbiont.

Conclusions

We conclude that the risk of acquiring Cat Scratch Disease or a related bartonellosis from questing ticks in the Netherlands is negligible. On the other hand fleas and deer keds are probable vectors for associated Bartonella species between animals and might also transmit Bartonella spp. to humans.

Role of sand lizards in the ecology of Lyme and other tick-borne diseases in the Netherlands

Background

Lizards are considered zooprophylactic for almost all Borrelia burgdorferi species, and act as dilution hosts in parts of North America. Whether European lizards significantly reduce the ability of B. burgdorferi to maintain itself in enzootic cycles, and consequently decrease the infection rate of Ixodes ricinus ticks for B. burgdorferi and other tick-borne pathogens in Western Europe is not clear.

Results

Ticks were collected from sand lizards, their habitat (heath) and from the adjacent forest. DNA of tick-borne pathogens was detected by PCR followed by reverse line blotting. Tick densities were measured at all four locations by blanket dragging. Nymphs and adult ticks collected from lizards had a significantly lower (1.4%) prevalence of B. burgdorferi sensu lato, compared to questing ticks in heath (24%) or forest (19%). The prevalence of Rickettsia helvetica was significantly higher in ticks from lizards (19%) than those from woodland (10%) whereas neither was significantly different from the prevalence in ticks from heather (15%). The prevalence of Anaplasma and Ehrlichia spp in heather (12%) and forest (14%) were comparable, but significantly lower in ticks from sand lizards (5.4%). The prevalence of Babesia spp in ticks varied between 0 and 5.3%. Tick load of lizards ranged from 1 - 16. Tick densities were ~ 5-fold lower in the heather areas than in woodlands at all four sites.

Conclusions

Despite their apparent low reservoir competence, the presence of sand lizards had insignificant impact on the B. burgdorferi s.l. infection rate of questing ticks. In contrast, sand lizards might act as reservoir hosts for R. helvetica. Remarkably, the public health risk from tick-borne diseases is approximately five times lower in heather than in woodland, due to the low tick densities in heather.

Seroprevalence of Rickettsia spp. infection among tick-bitten patients and blood donors in Sweden

Serum samples from 236 Swedish patients with symptoms of infectious disease appearing after a tick bite were analysed for the presence of antibodies to Rickettsia helvetica, the only rickettsial species so far isolated from ticks in Sweden. Of these subjects, 137 had tested seropositive for Borrelia burgdorferi. For control purposes, sera from 161 healthy blood donors were examined. A total of 10/397 samples (2.6%) showed IgG-antibodies to R. helvetica at or above a titre of 1/80 as cut-off. 6/137 (4.4%) belonged to the Borrelia positive group, 3/99 (3.0%) to the tick-bitten but Borrelia negative group and 1/161 (0.6%) to the control group. The difference between the tick-exposed groups and the control group was significant in Pearson's 2-sided chi(2) test. In 1 serum sample the presence of antibodies to R. helvetica was further confirmed by Western immunoblot. The study shows that infection with Rickettsia spp. as well as coinfection with Lyme borreliosis needs to be considered in the diagnosis of tick-transmitted infections in Sweden. Owing to a known occurrence of immunological cross-reactivites, however, the results must be cautiously interpreted with regard to species of Rickettsia involved.

Molecular Investigations of Rickettsia helvetica infection in dogs, foxes, humans, and Ixodes ticks

Rickettsia helvetica, a tick-borne member of the spotted-fever-group rickettsiae, is a suspected pathogen in humans; however, its role in animals is unknown. The aims of this study were to establish a R. helvetica-specific real-time TaqMan PCR assay and apply it to the analysis of tick vectors (to determine potential exposure risk) and blood samples from Canidae and humans (to determine prevalence of infection). The newly designed 23S rRNA gene assay for R. helvetica was more sensitive than a published citrate synthase gene (gltA) assay for several rickettsiae. Blood samples from 884 dogs, 58 foxes, and 214 human patients and 2,073 ticks (Ixodes spp.) collected from either vegetation or animals were analyzed. Although the maximal likelihood estimate of prevalence was 12% in unfed ticks and 36% in ticks collected from animals, none of the 1,156 blood samples tested PCR positive. Ticks from cats were more frequently PCR positive than ticks from dogs. Sequencing of the 23S rRNA and/or the gltA gene of 17 tick pools confirmed the presence of R. helvetica. Additionally, Rickettsia monacensis, which has not been previously found in Switzerland, was identified. In conclusion, R. helvetica was frequently detected in the tick population but not in blood samples. Nevertheless, due to the broad host range of Ixodes ticks and the high rate of infestation with this agent (i.e., R. helvetica was 13 times more frequent in unfed ticks than the tick-borne encephalitis virus), many mammals may be exposed to R. helvetica. The PCR assay described here represents an important tool for studying this topic.

Presence of Chlamydophila pneumoniae DNA but not mRNA in stenotic aortic heart valves

BACKGROUND

The pathogenesis of aortic valve stenosis may involve inflammation and we have previously demonstrated Chlamydophila pneumoniae (C. pneumoniae) DNA in stenotic aortic heart valves. Dissemination of these bacteria is probably mediated by alveolar macrophages. Bacterial DNA alone does not indicate whether the bacteria are viable and replicating. This study aimed to investigate the presence of C. pneumoniae mRNA, a marker of replicating bacteria, and C. pneumoniae DNA in stenotic aortic valves and the prevalence of C. pneumoniae in peripheral blood mononuclear cells (PBMC).

METHODS

DNA was extracted from heart valves and PBMC and mRNA from heart valves from 76 patients undergoing aortic valve replacement surgery. C. pneumoniae DNA and mRNA were measured by real-time PCR targeting the ompA gene.

RESULTS

C. pneumoniae DNA was demonstrated in 22% of heart valves and in 5% of PBMC. C. pneumoniae mRNA was not detected in any valve. Patients positive for C. pneumoniae in the valve underwent coronary artery by-pass grafting more often (p=0.01) and suffered from angina pectoris (p=0.02) and arterial hypertension (p=0.03) more often than patients negative for C. pneumoniae in the valve.

CONCLUSIONS

These findings support a role for C. pneumoniae in the pathogenesis of aortic valve stenosis and indicate that the bacteria disseminate from the respiratory tract long before the patients were in need of surgery and that the valve infection thereafter entered into a persistent and non-replicative state. Moreover, patients positive for C. pneumoniae in the valve more often needed by-pass grafting because of more advanced coronary disease.

Spotted fever group rickettsiae in ticks, Morocco

Identified rickettsiae were 4 pathogens, 2 suspected pathogens, and 1 incompletely described species.

A total of 370 ticks, encompassing 7 species from 4 genera, were collected during 2002–2006 from domestic animals and vegetation in the Taza region of northeastern Morocco. Rickettsial DNA was identified in 101 ticks (27%) by sequencing PCR products of fragments of the citrate synthase and outer membrane protein genes of Rickettsia spp. Seven rickettsiae of the spotted fever group were identified, including 4 pathogens: R. aeschlimannii in Hyalomma marginatum marginatum, R. massiliae in Rhipicephalus sanguineus, R. slovaca in Dermacentor marginatus, and R. monacensis in Ixodes ricinus. Two suspected pathogens were also detected (R. raoultii in D. marginatus and R. helvetica in I. ricinus). An incompletely described Rickettsia sp. was detected in Haemaphysalis spp. ticks.

Unusual concurrent detection by polymerase chain reaction of Bartonella henselae and parvovirus b19 in an immunocompetent child with erythema nodosum and hepatic granulomatous disease

We report an unusual case of documented Bartonella henselae genotype I from hepatic tissue in an Italian immunocompetent girl presenting with erythema nodosum and hepatic granulomata. Polymerase chain reaction (PCR) was performed on biopsied liver sample to confirm the etiologic role of B. henselae and to identify the genetic variant of this organism. A PCR on the same liver biopsy for parvovirus B19 was also positive, but the clinical meaning of this was not clear.

Spotted fever rickettsioses in southern and eastern Europe

Mediterranean spotted fever due to Rickettsia conorii conorii was thought, for many years, to be the only tick-borne rickettsial disease prevalent in southern and eastern Europe. However, in recent years, six more species or subspecies within the spotted fever group of the genus Rickettsia have been described as emerging pathogens in this part of the world. Tick-borne agents include Rickettsia conorii israelensis, Rickettsia conorii caspia, Rickettsia aeschlimannii, Rickettsia slovaca, Rickettsia sibirica mongolitimonae and Rickettsia massiliae. Many Rickettsia of unknown pathogenicity have also been detected from ticks and could represent potential emerging pathogens to be discovered in the future. Furthermore, a new spotted fever rickettsia, Rickettsia felis, was found to be associated with cat fleas and is an emerging human pathogen. Finally, the mite-transmitted Rickettsia akari, the agent of rickettsialpox, is also known to be prevalent in Europe. We present here an overview of these rickettsioses, focusing on emerging diseases.

Rickettsial Infections

Rickettsiae are obligate intracellular alpha-proteobacteria that primarily target the microvascular endothelium. In the last two decades, new rickettsial pathogens have been associated with human illness around the world. Clinically, the common denominator in all rickettsioses is the development of increased microvascular permeability, leading to cerebral and non-cardiogenic pulmonary edema. With the development of powerful research tools, advances in the understanding of rickettsial pathogenesis have been dramatic. Entry into the host cell is followed by rapid escape into the cytoplasm to avoid phagolysosomal fusion. Spotted fever group rickettsiae induce actin polymerization via a group of proteins called RickA, which promote nucleation of actin monomers via the Arp2/3 complex at one rickettsial pole, propelling the bacteria across the cytoplasm and into neighboring cells. Damage to the host cell is most likely multifactorial. The most extensively studied mechanism is the generation of reactive oxygen species (ROS) and downregulation of enzymes involved in protection against oxidative injury. The significance of ROS-mediated cellular damage in vivo is beginning to be elucidated. The main pathogenic mechanism is increased microvascular permeability leading to profound metabolic disturbances in the extravascular compartment. The underlying factors responsible for those changes are beginning to be elucidated in vitro and include direct effects of intracellular rickettsiae, cytokines, and possibly activated coagulation factors--all of which most likely modify interendothelial junctions. Our knowledge on rickettsial pathogenesis will continue to expand in the near future as new research tools become available.