Clinical problem-solving. Index of suspicion

Early post-transplant cutaneous bacillary angiomatosis in a kidney recipient: Case report and review of the literature

Bacillary angiomatosis (BA) is an uncommon systemic disease caused by Bartonella henselae (BH) or Bartonella quintana (BQ) that occurs primarily in immunocompromised hosts. Few cases of BA recipients have been reported in adult solid transplant recipients over the years, with most cases presenting years after transplant. We describe a case of a kidney transplant recipient who developed cutaneous BA very early in the post-transplant period despite not having any exposures. Retrospective testing of donor and recipient's serum was performed and raised the concern for possible donor-derived infection. A literature review encompassing 1990 to present was also performed in order to better understand the clinical presentation, diagnostics and therapeutic approach of this unusual disease. Combined serology, histopathology and molecular testing (polymerase chain reaction [PCR]) were useful in diagnosing BA in our patient as serology alone might be unreliable. Macrolides or doxycycline for at least 3 months is the recommended therapeutic strategy; however, the optimal duration of treatment is not well established in transplant recipients. In our patient, we decided to use doxycycline for 1 year due to gradual resolution of lesions and ongoing immunosuppression. Patient responded successfully without any documented relapse.

An unexpected case of Bartonella alsatica prosthetic vascular graft infection

Bartonella alsatica is a wild rabbit pathogen causing bacteremia rarely reported in humans, with only three cases published so far, including one lymphadenitis and two endocarditis cases. Here, we report the case of a 66-year-old man who suffered from acute renal failure due to a membranoproliferative glomerulonephritis. Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) showed diffuse FDG uptake around the aortobifemoral graft with no indication of infection. A white blood cell scan showed an accumulation of labeled neutrophils on the left femoral part of the graft. The patient underwent surgery and an abscess around the left iliac part of the graft was found intraoperatively. Intraoperative samples were all negative, but 16S rRNA gene-based PCR was positive, and the sequence was positioned among the Bartonella species cluster. Specific PCRs targeting groEL/hsp60, rpoB and gltA genes were performed and led to the identification of B. alsatica. Accordingly, indirect immunofluorescence serological analyses were positive for Bartonella henselae and Bartonella quintana. The patient had a history of regularly hunting wild rabbits. He was treated with 100 mg of doxycycline twice a day for six months and his renal function significantly improved with no sign of persistent infection. This case highlights the contribution of serology assays and molecular-based methods in prosthetic vascular graft infection diagnosis.

Bartonella henselae infections in solid organ transplant recipients: report of 5 cases and review of the literature

Bartonella henselae is the causative agent of cat scratch disease and bacillary angiomatosis-peliosis. The spectrum of disease, diagnosis, and management of B. henselae infection in solid organ transplant recipients has not been well characterized. We identified 29 cases of solid organ transplant recipients who had Bartonella infection, 24 by a review of the English-language literature and 5 from our institution. Localized cat scratch disease was found in 8 patients (28%), and disseminated infection was found in 21 patients (72%). The mean time after transplantation to development of Bartonella infection among those with cat scratch disease was 5.6 ± 5.3 years, and among those with disseminated infection was 2.7 ± 2.4 years. Prominent clinical features included cat exposure in 26 patients (90%), fever in 27 patients (93%), lymphadenopathy in 12 patients (41%), and skin lesions in 7 patients (24%). Methods used in establishing the diagnosis of Bartonella infection included culture, polymerase chain reaction (PCR) assay, serologic assays, and histopathologic examination. Culture was positive in 2 of only 4 patients in whom this was performed, and PCR was positive in 12 of 14 patients (86%) in whom this test was performed. Serologic assays were positive in all 23 patients who were tested. Histopathologic examination of tissues in all 8 patients who had cat scratch disease revealed granulomatous inflammation in 4 (50%) and bacillary angiomatosis-peliosis in 2 (25%). Among the 15 patients who had disseminated infection and who had tissue examined, 8 (53%) had only granulomatous inflammation, 4 had only bacillary angiomatosis-peliosis (27%), and 2 had both granulomas and bacillary angiomatosis-peliosis (13%). A positive Warthin-Starry or Steiner stain was noted in 12 of 19 patients (63%) who had 1 of these stains performed. All 8 patients with cat scratch disease and 19 of 21 patients with disseminated bartonellosis were cured with antimicrobial therapy. Two patients, both of whom had endocarditis, died. Among solid organ transplant recipients, infection with B. henselae is uncommon and has diverse disease manifestations including disseminated disease. Persistent fevers or lymphadenopathy in a transplant recipient who has been exposed to cats should prompt clinicians to maintain a high index of suspicion for B. henselae infection. Identifying B. henselae as the causative organism often requires multiple diagnostic studies. Once the diagnosis is established, most solid organ transplant recipients respond appropriately to antimicrobial treatment.

Cutaneous bacillary angiomatosis in renal transplant recipients: report of three new cases and literature review

Bacillary angiomatosis (BA) is a rare vasculoproliferative disorder due to Bartonella henselae (BH) or Bartonella quintana. It can involve many organs, including the skin, and has been mainly reported in patients with acquired immunodeficiency syndrome. In organ transplant recipients (OTR), this disorder remains misdiagnosed and therapeutic guidelines are nonexistent. We report 3 cases of BA with skin involvement in OTR and review similar cases from the literature. BA manifests on the skin with violaceous lesions mimicking Kaposi sarcoma, and is associated with fever, lymphadenopathy, and liver, spleen, or lung nodules. Bartonellosis infections in OTR are due to BH, the agent causing cat-scratch disease (CSD), but BA comprises histologically a prominent vascular proliferation, which is usually lacking in CSD. Cultures and serologic tests are poorly reliable for the diagnosis, which relies on demonstration of BH within the lesions. A history of cat exposure exists in most cases and pediatric OTR are at higher risk. Prevention consists of regular use of a flea-control product in cats and prompt cleaning of scratches. Our cases highlight several original features of this rare condition, which could potentially improve the management of BA in OTR.

Perspective: Uses and misuses of thresholds in diagnostic decision making

The concept of thresholds plays a vital role in decisions involving the initiation, continuation, and completion of diagnostic testing. Much research has focused on the development of explicit thresholds, in the form of practice guidelines and decision analyses. However, these tools are used infrequently; most medical decisions are made at the bedside, using implicit thresholds. Study of these thresholds can lead to a deeper understanding of clinical decision making. The authors examine some factors constituting individual clinicians' implicit thresholds. They propose a model for static thresholds using the concept of situational gravity to explain why some thresholds are high, and some low. Next, they consider the hypothetical effects of incorrect placement of thresholds (miscalibration) and changes to thresholds during diagnosis (manipulation). They demonstrate these concepts using common clinical scenarios. Through analysis of miscalibration of thresholds, the authors demonstrate some common maladaptive clinical behaviors, which are nevertheless internally consistent. They then explain how manipulation of thresholds gives rise to common cognitive heuristics including premature closure and anchoring. They also discuss the case where no threshold has been exceeded despite exhaustive collection of data, which commonly leads to application of the availability or representativeness heuristics. Awareness of implicit thresholds allows for a more effective understanding of the processes of medical decision making and, possibly, to the avoidance of detrimental heuristics and their associated medical errors. Research toward accurately defining these thresholds for individual physicians and toward determining their dynamic properties during the diagnostic process may yield valuable insights.

Cat-scratch disease relapse in a kidney transplant recipient

Cat-scratch disease, an infectious illness infrequently reported in kidney transplant patients, is caused by the organism Bartonella henselae and is transmitted through contact with cats or kittens. It is a self-limited disorder in the general pediatric population. Here we present a case of unsuspected cat-scratch disease in a pediatric kidney transplant patient who presented with fever and lymphadenopathy. Eight months after treatment with a short course of azithromycin, the patient developed a recurrence of cat-scratch disease. We emphasize that the evaluation of a young immunocompromised kidney transplant patient presenting with fever and lymphadenopathy should include unusual infections such as cat-scratch disease. We review the diagnosis and treatment of this uncommon infection in the organ transplant population.

Disseminated Bartonella infection following liver transplantation*

Bartonella henselae has not only been identified as the causative agent of cat scratch disease, but it is also associated with other significant infectious syndromes in the immunocompromised population. We describe two cases of B. henselae associated diseases in liver transplant recipients who both had contact with cats. The first recipient developed localized skin manifestation of bacillary angiomatosis in association with granulomatous hepatitis. He tested positive for Immunoglobulin G (IgG) antibodies against B. henselae. The second patient developed axillary lymphadenopathy, with biopsy showing necrotizing granulomatous inflammation and polymerase chain reaction studies were positive for B. henselae DNA. Her serology for bartonellosis showed a fourfold rise in antibody titers during her hospitalization. Both patients responded to treatment with Azithromycin in combination with Doxycycline. These were the only cases within a series of 467 consecutive liver transplants performed in 402 patients performed during a 4-year period. Although bartonellosis is a rare infection in liver transplantation recipients, it should always be included in the differential diagnosis of patients presenting with fever, central nervous system (CNS) symptoms, skin lesions, lymphadenopathy, and hepatitis especially if prior contact with cats is reported.