Possible role of tick-borne infection in "cat-scratch disease": comment on the article by Giladi et al.
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Bartonella quintana, the aetiologic agent of trench fever, has recently been implicated in culture-negative endocarditis and bacteraemia amongst homeless people. B. quintana is a fastidious slow-growing organism. A tissue culture system of human endothelial cells was developed in which B. quintana grew intracellularly. Observation of the different steps during infection of these cells demonstrated that the bacteria adhered to and penetrated the cells by phagocytosis. During the preadherence stage, most bacteria exhibited surface appendages that resembled those described for Salmonella typhimurium and which may mediate specific interactions between the eucaryotic cell and the bacterium. Soon after the engulfment step, the bacterium appeared in a cell vacuole where it multiplied, giving the typical aspect of morulae which has also been reported with Ehrlichiae or Chlamydiae. In older cultures, the coexistence of bacteria and huge quantities of vesicle-like structures in the same vacuole were noted. These vesicle-like structures were also found with agar-grown bacteria and were identified as membrane blebs. Microscopic observation of heart valves from B. quintana endocarditis patients demonstrated the intracellular location of B. quintana in vivo. This intracellular location of B. quintana should now be considered in further studies on the pathogenesis of the diseases it causes.
The seroprevalence of Bartonella henselae and Toxoplasma gondii among apparently healthy individuals, mainly blood donors, in Thailand was investigated by an indirect fluorescent antibody technique and by a latex agglutination test, respectively. Of 163 serum samples examined, 9 (5.5%) were found to be positive for B. henselae-IgG, 2 (1.2%) for B. henselae-IgM, and 5 (3.1%) for the T. gondii antibody. No significant difference was observed between male and female samples in the serological test with either B. henselae or T. gondii. The age of individuals with B. henselae-IgG was distributed from the 20s to the 70s, and B. henselae-IgM was found in the individuals of the 30s and 60s. The age of T. gondii positive samples ranged from the 20s to the 60s. In this study, the prevalence of B. henselae infection among healthy individuals in Thailand was serologically demonstrated for the first time.
Gray squirrels, Sciurus carolinensis, were livetrapped in 2 different habitat types, woodland (67 squirrels) and parkland (53 squirrels), in southeastern Georgia. Ectoparasites were recovered from anesthetized squirrels and compared between hosts from the 2 habitats. Because of the absence of low vegetation in parkland habitats, it was hypothesized that the ectoparasite fauna, especially ticks and chiggers, would be more diverse on woodland squirrels. The results were generally in agreement with this hypothesis. Seventeen species of ectoparasites were recovered from woodland squirrels, compared with 6 species from parkland squirrels. Five species of ticks and 3 species of chiggers parasitized the woodland squirrels compared with no ticks or chiggers on the parkland squirrels. Significantly higher infestation prevalences were recorded on woodland compared with parkland squirrels for the flea Orchopeas howardi, the tick Amblyomma americanum, and the mesostigmatid mite Androlaelaps fahrenholzi. The mean intensity for O. howardi also was significantly higher on woodland than on parkland squirrels. Because a new strain of Bartonella sp. was isolated recently from S. carolinensis in Georgia, selected ectoparasites from this study were screened for bartonellae by polymerase chain reaction (PCR). Some of the fleas and lice, but none of the mites tested, were PCR positive, suggesting that fleas, or lice, or both, might be vectors of bartonellae between squirrels. Six distinct strains of Bartonella sp. were detected, 2 in fleas and 4 in lice.
Many pathogens actively exploit the actin cytoskeleton during infection. This exploitation may take place during entry into mammalian cells after engagement of a receptor and/or as series of signaling events culminating in the engulfment of the microorganism. Although actin rearrangements are a common feature of most internalization events (e.g. entry of Listeria, Salmonella, Shigella, Yersinia, Neisseria, and Bartonella), bacterial and other cellular factors involved in entry are specific to each bacterium. Another step during which pathogens harness the actin cytoskeleton takes place in the cytosol, within which some bacteria (Listeria, Shigella, Rickettsia) or viruses (vaccinia virus) are able to move. Movement is coupled to a polarized actin polymerization process, with the formation of characteristic actin tails. Increasing attention has focused on this phenomenon due to its striking similarity to cellular events occurring at the leading edge of locomoting cells. Thus pathogens are convenient systems in which to study actin cytoskeleton rearrangements in response to stimuli at the plasma membrane or inside cells.
The proliferation of human umbilical vein endothelial cells (HUVECs) cocultivated with live B. henselae was enhanced in a bacterial dose-dependent manner, and the stimulatory effect was specific to vascular endothelial cells. The inactivation of B. henselae by UV or heat treatment abolished its stimulatory activity, suggesting that live bacteria is necessary for the growth stimulation effect. To investigate the role of direct contact, live B. henselae were separated from HUVECs by a filter membrane (Millicell-CM insert). Even under this condition, an enhanced proliferation of HUVECs was observed. However, no morphological changes in the HUVECs were apparent compared to the B. henselae -infected cells. Furthermore, we isolated a nonpiliated strain of B. henselae that is unable to attach to and enter into endothelial cells. The nonpiliated strain possessed the ability to stimulate the proliferation of cocultivated HUVECs the same as the piliated strain. Moreover, the culture supernatants of B. henselae were also able to induce HUVEC proliferation. Our results indicate that the stimulation of HUVEC proliferation by B. henselae is mediated by soluble factor(s) secreted from the bacteria.
Bartonella henselae is the causative agent of cat-scratch disease (CSD), which usually manifests as acute regional lymphadenopathy. The causes of cervical lymphadenopathy, with special regard to CSD, were investigated in a study of 454 patients who presented with unclear masses in the head and neck from January 1997 through January 2001. Sixty-one patients (13.4%) experienced CSD; 54 (11.9%) had primary lymphadenopathy due to other infectious agents, and 41 (9.0%) had lymphadenopathy that occurred in association with primary infections of other organs. For 171 patients (37.7%), the cause of the cervical lymph node enlargement could not be found. B. henselae DNA was detected in extirpated lymph nodes only during the first 6 weeks of lymphadenopathy, which indicates that the results of polymerase chain reaction strongly depend on the duration of illness. CSD should be included in the differential diagnosis of adenopathy in the otorhinolaryngologic patient population, to avoid unnecessary treatment.
Serological and epidemiological studies suggest that Bartonella henselae is the etiological agent of cat scratch disease. We designed a study to detect B. henselae in archival biopsies by polymerase chain reaction amplification of the 16S rRNA gene followed by Southern blot hybridization. Forty-two histologically defined cat scratch disease biopsies and eighteen controls were selected for blinded analysis. After testing, charts were reviewed for clinical, immunological, and microbial evidence of infection. Results were correlated with duration of illness and antimicrobial therapy. B. henselae DNA was identified in 27 of 42 (64%) histologically defined patients and 23 of 34 (68%) patients defined both clinically and histologically. There were no false positives (0 of 18). A small subset (n = 14) had cat scratch disease serological tests performed. B. henselae was identified in 8 of 10 serologically positive patients. Polymerase chain reaction detected 50% of our DNA-positive cases (most of these early in the clinical course). Southern blotting of amplicons both doubled sensitivity (detecting patients > 4 weeks into illness) and confirmed B. henselae as the causative species. Our study strongly associates B. henselae with cat scratch disease, suggesting that it may be the most likely etiological agent in the majority of patients with cat scratch disease.
Ticks play an important role in the transmission of arthropod-borne diseases of viral, protozoal and bacterial origin. The present article describes a molecular-biological based method, which facilitated the broad-range analyses of bacterial communities in ixodid ticks (Ixodes ricinus). DNA was extracted both from single ticks and pooled adult ticks. Eubacterial 16S rRNA gene fragments (16S rDNA) were amplified by polymerase chain reaction (PCR) with broad-range ribosomal primers. Sequences spanning the hypervariable V3 region of the 16S rDNA and representing individual bacterial taxons were separated by denaturing gradient gel electrophoresis (DGGE). For phylogenetic identification, DGGE bands were exised, cloned and sequenced. In addition, we set up a 16S rDNA clone library which was screened by DGGE. Sequences were compared with sequences of known bacteria listed in the GenBank database. A number of bacteria were affiliated with the genera Rickettsia, Bartonella, and Borrelia, which are known to be pathogenic and transmitted by ticks. Two sequences were related to the yet to be cultivated Haemobartonella. To our knowledge, Haemobartonella has never been directly detected in I. ricinus. In addition, members of the genera Staphylococcus, Rhodococcus, Pseudomonas, and Moraxella were detected, which have not been identified in ticks so far. Two bacteria were most closely related to a rickettsial endosymbiont of an Acanthamoeba sp., and to an endosymbiont (Legionellaceae, Coxiella group) of the microarthropod Folsomia candida. The results prove that 16S rDNA genotyping in combination with DGGE analysis is a promising approach for the detection and identification of bacteria infecting ticks, regardless of whether these bacteria are fastidious, obligate intracellular or noncultivable.
The emergence of Lyme borreliosis as a public health burden within the last two decades has stimulated renewed interest in tick-borne infections. This attention towards ticks, coupled with advances in detection technologies, has promoted the recognition of diverse emergent or potentially emerging infections, such as monocytic and granulocytic ehrlichiosis, local variants of spotted fever group rickettsioses, WA-1 babesiosis, or a Lyme disease mimic (Masters' Disease). The distribution of pathogens associated with well-described tick-borne zoonoses such as human babesiosis due to Babesia microti or B. divergens seems wider than previously thought. Bartonellae, previously known to be maintained by fleas, lice or sandflies, have been detected within ticks. Purported 'new' agents, mainly identified by sequencing of PCR products and comparison with those sequences present in GenBank, are being increasingly reported from ticks. We briefly review the diversity of these infectious agents, identify aetiological enigmas that remain to be solved, and provide a reminder about 'old friends' that should not be forgotten in our pursuit of novelty. We suggest that newly recognised agents or tick/pathogen associations receive careful scrutiny before being declared as potential public health burdens.
Bartonella quintana causes trench fever, endocarditis, and the vasculoproliferative disorders bacillary angiomatosis and peliosis hepatis in humans. Little is known about the interaction of this pathogen with host cells. We attempted to elucidate the interaction of B. quintana with human macrophages (THP-1) and epithelial cells (HeLa 229). Remarkably, only B. quintana strain JK-31 induced secretion of vascular endothelial growth factor (VEGF) from THP-1 and HeLa 229 cells upon infection similar to the secretion induced by B. henselae Marseille, whereas other strains (B. quintana 2-D70, B. quintana Toulouse, and B. quintana Munich) did not induce such secretion. Immunofluorescence testing and electron microscopy revealed that the B. quintana strains unable to induce VEGF secretion did not express the variable outer membrane proteins (Vomps) on their surfaces. Surprisingly, the increase in VEGF secretion mediated by B. quintana JK-31 was not paralleled by elevated host cell adherence rates compared with the rates for Vomp-negative B. quintana strains. Our results suggest that the Vomps play a leading role in the angiogenic reprogramming of host cells by B. quintana but not in the adherence to host cells.
The etiologic diagnosis of infective endocarditis is easily made in the presence of continuous bacteremia with gram-positive cocci. However, the blood culture may contain a bacterium rarely associated with endocarditis, such as Lactobacillus spp., Klebsiella spp., or nontoxigenic Corynebacterium, Salmonella, Gemella, Campylobacter, Aeromonas, Yersinia, Nocardia, Pasteurella, Listeria, or Erysipelothrix spp., that requires further investigation to establish the relationship with endocarditis, or the blood culture may be uninformative despite a supportive clinical evaluation. In the latter case, the etiologic agents are either fastidious extracellular or intracellular bacteria. Fastidious extracellular bacteria such as Abiotrophia, HACEK group bacteria, Clostridium, Brucella, Legionella, Mycobacterium, and Bartonella spp. need supplemented media, prolonged incubation time, and special culture conditions. Intracellular bacteria such as Coxiella burnetii cannot be isolated routinely. The two most prevalent etiologic agents of culture-negative endocarditis are C. burnetti and Bartonella spp. Their diagnosis is usually carried out serologically. A systemic pathologic examination of excised heart valves including periodic acid-Schiff (PAS) staining and molecular methods has allowed the identification of Whipple's bacillus endocarditis. Pathologic examination of the valve using special staining, such as Warthin-Starry, Gimenez, and PAS, and broad-spectrum PCR should be performed systematically when no etiologic diagnosis is evident through routine laboratory evaluation.
Although endemic throughout much of the world, autochthonous visceral leishmaniasis has been reported on only 3 previous occasions in North America. After diagnosis of visceral leishmaniasis in 4 foxhounds from a kennel in Dutchess County, New York (index kennel), serum and ethylenediamine-tetraacetic acid (EDTA)-anticoagulated blood were collected from the remaining 108 American or cross-bred foxhounds in the index kennel and from 30 Beagles and Basset Hounds that were periodically housed in the index kennel. Samples were analyzed for antibodies to or DNA of tickborne disease pathogens and Leishmania spp. Most dogs had antibodies to Rickettsia spp., Ehrlichia spp., Babesia spp., or some combination of these pathogens but not to Bartonella vinsonii (berkhoffi). However, DNA of rickettsial, ehrlichial, or babesial agents was detected in only 9 dogs. Visceral leishmaniasis was diagnosed in 46 of 112 (41%) foxhounds from the index kennel but was not diagnosed in any of the Beagles and Basset Hounds. A positive Leishmania status was defined by 1 or more of the following criteria: a Leishmania antibody titer > or = 1:64, positive Leishmania polymerase chain reaction (PCR), positive Leishmania culture, or identification of Leishmania amastigotes by cytology or histopathology. The species and zymodeme of Leishmania that infected the foxhounds was determined to be Leishmania infantum MON-1 by isoenzyme electrophoresis. Foxhounds that were > 18 months of age or that had traveled to the southeastern United States were more likely to be diagnosed with visceral leishmaniasis. Transmission of Leishmania spp. in kennel outbreaks may involve exposure to an insect vector, direct transmission, or vertical transmission.
Invasive disease due to group A beta-hemolytic streptococci (GABHS) can be divided into 3 categories of disease: streptococcal toxic shock syndrome (strepTSS), necrotizing fasciitis, and other invasive GABHS disease. Patients with strepTSS may have multiorgan failure within hours of presentation. Clindamycin and penicillin G should be used in combination for treatment of invasive GABHS disease. The mortality rate for menstrual staphylococcal toxic shock syndrome has decreased with early recognition and treatment, and removal of hyperabsorbent tampons from the market. Kawasaki syndrome (KS) is the most common cause of acquired heart disease in children in the U. S., and atypical forms have a higher mortality rate than typical KS. Hantavirus pulmonary syndrome is a zoonosis with an 80% mortality rate if the diagnosis is not made on first presentation and patients return to the hospital in shock. Children and adolescents with Lyme disease have an excellent prognosis and respond well to antimicrobial therapy. Cat scratch disease (CSD) is caused by Bartonella henselae and is transmitted by flea-infested kittens. CSD lymphadenopathy typically resolves spontaneously in 2ñ3 months; however, there is a 50% likelihood of resolution in 1 month if patients receive a 5-day treatment course with azithromycin.
OBJECTIVE: To study the etiology and seroepidemiology of cat-scratch disease (CSD) in Hawaii. METHODS: Blood and fine-needle aspirate (FNA) from the lymph nodes of 39 consecutive patients with clinical CSD were cultured for Bartonella henselae, and blood samples from index cats, stray cats, and dogs were cultured and their sera were tested by indirect fluorescence antibody test for antibodies to B. henselae and Afipia felis. Sera from age- and sex-matched human subjects without cat exposure served as controls. RESULTS: Warthin-Starry staining showed positive results in only 4 of 32 FNAs, and B. henselae was isolated from only one FNA specimen. All of 38 patients who had two or more sera tested had elevated titers of antibody to B. henselae. Only 1 of 48 human control sera had antibody to B. henselae. Of 31 kittens, 21 had positive blood culture results and elevated antibody titers to B. henselae. Of three adult cats, all had negative blood culture results, but they had serologic evidence of past infection. Of 23 adult stray cats, 18 had elevated titers of antibody to B. henselae, but in only one was the blood culture result positive. Results of IFA tests were marginally positive for A. felis in 1 of 29 patients with CSD and in one adult stray cat and one dog. CONCLUSIONS: This study shows that the B. henselae IFA test is both highly sensitive and specific for the detection of infection caused by B. henselae and for the laboratory diagnosis of CSD, and that FNA is seldom helpful in confirming the diagnosis. We further demonstrated that CSD in Hawaii is due to B. henselae and that infection is directly linked to the scratch or bite of a kitten. Older cats seldom have bacteremia but often have serologic evidence of past infection. Our study fails to implicate dogs in the epidemiology of CSD in Hawaii, and A. felis was not etiologically implicated in CSD in the human subjects and animals we studied.
IE is a serious, life-threatening disease. Because treatment must often be adapted to the pathogen involved, rapid identification of the etiologic agent is critical to successful management of each patient. When difficult-to-culture pathogens are involved, routine microbiologic tests, including blood culture, may remain negative. Because such cases may account for up to 31% of all IE cases, alternative diagnostic approaches are necessary. Among the etiologic agents of culture-negative endocarditis, C burnetii and Bartonella spp play a major role; each is responsible for up to 3% of episodes of IE. The authors therefore recommend the systematic use of specific serologies in all cases of clinically suspected endocarditis. The cross-reactivity between C burnetii, Bartonella spp, and Chlamydia spp is of diagnostic importance because all are potential etiologic agents of endocarditis. However, given that the levels of specific antibodies observed in Bartonella endocarditis are extremely high, low-level cross-reactions with other antigens should not lead to misdiagnosis, provided serology for all suspected agents is performed. When serologic test results are negative for both Bartonella spp and C burnetii, special staining by the Gram, Giemsa, Gimenez, PAS, Warthin-Starry, and Grocott methods may guide the use of new diagnostic tools such as PCR and tissue culture for isolation and identification of the causative agent. Such novel approaches may lead to more comprehensive patient evaluations and the discovery of new etiologic agents of IE.
In two homeless men aged 38 and 32 years, who suffered from itching, infestation with body lice (Pediculus humanus var. corporis, a.k.a. clothes lice) was diagnosed. This infestation is rare in the Netherlands. In 1993 and 1994 and infection with body lice was registered 41 times in 31 patients at the clinic for homeless of the Community Health Service of Utrecht. The body louse can be seen by the naked eye. Treatment is by hygienic measures, pediculicides if necessary, and by prevention. Important to recognize is that P. humanus can be the vector of trench fever (Bartonella quintana), relapsing fever and typhus.
Norway rats (Rattus norvegicus) carry several zoonotic pathogens and because rats and humans live in close proximity in urban environments, there exists potential for transmission. To identify zoonotic agents carried by rats in Baltimore, Maryland, USA, we live-trapped 201 rats during 2005-2006 and screened them for a panel of viruses, bacteria, and parasites. Antibodies against Seoul virus (57.7%), hepatitis E virus (HEV, 73.5%), Leptospira interrogans (65.3%), Bartonella elizabethae (34.1%), and Rickettsia typhi (7.0%) were detected in Norway rats. Endoparasites, including Calodium hepatica (87.9%) and Hymenolepis sp. (34.4%), and ectoparasites (13.9%, primarily Laelaps echidninus) also were present. The risk of human exposure to these pathogens is a significant public health concern. Because these pathogens cause non-specific and often self-limiting symptoms in humans, infection in human populations is probably underdiagnosed.