Search Results (34)

Background and Clinical Significance: Disseminated nocardiosis is a rare, life-threatening infection, often misdiagnosed due to its resemblance to other conditions. Case Presentation: A 62-year-old post-renal transplant patient presented with pulmonary, hepatic, and pancreatic lesions. Despite multiple negative bacterial cultures, a histopathological examination of the liver revealed necrotizing granulomas with filamentous microorganisms, ultimately identified as Nocardia. Conclusions: This case highlights diagnostic challenges and the importance of integrating microbiological, pathological, and radiographical findings to manage and diagnose disseminated nocardiosis infections in immunocompromised individuals. Full article

Nocardia spp. are opportunistic pathogens of humans, domestic animals, and wildlife that can cause high levels of morbidity and mortality. Here, we present a unique case of nocardial airsacculitis in a free-ranging mallard (Anas platyrhynchos) from Arizona, USA, and compare it to the hosts, geographic distribution, diagnostic methodology, and infection site of known nocardiosis cases in birds. A gross necropsy, histopathology, and bacterial culture were performed. There were no gross findings associated with the nocardiosis. Histopathology showed multiple granulomas expanding the air sac with intralesional filamentous bacteria that were Grocott’s methenamine silver-positive, Fite–Faraco and Ziehl–Neelsen acid-fast, positive with the Periodic acid–Schiff reaction, and variably Gram-positive. The organism was isolated in culture and identified as Nocardia cyriacigeorgica based on the sequencing of a 463 bp portion of the 16S rRNA gene. While reports of nocardiosis in the class Aves are rare and some are possibly misdiagnosed due to limited diagnostics, cases are reported globally, sometimes resulting in epizootics. More information is needed to understand whether immunosuppression plays a role in disease development in birds. Known to be an emerging pathogen in humans, N. cyriacigeorgica can be considered as a differential diagnosis for pulmonary and potentially cutaneous or disseminated infections in birds. Full article

Pulmonary nocardiosis (PN) is a rare, opportunistic, and potentially life-threatening infection, especially in disseminated cases. This retrospective study aimed to characterize the clinical features of PN and assess the diagnostic utility of metagenomic next-generation sequencing (mNGS). We reviewed data from 19 patients diagnosed with PN between September 2019 and August 2022, including 3 with disseminated disease. Common symptoms included fever, cough, and sputum production, while chest imaging frequently revealed nodules, consolidations, exudates, cavities, and pleural effusions. The sensitivity of mNGS for detecting Nocardia was significantly higher than that of culture (100% vs. 36.84%, p < 0.001). mNGS successfully identified Nocardia species and co-infected pathogens. The most common species was Nocardia farcinica. Four PN cases were co-infected with Rhizomucor pusillus, Cryptococcus neoformans, Lichtheimia ramosa, and Aspergillus spp. Eighteen patients (94.7%) received trimethoprim-sulfamethoxazole (TMP-SMZ). Sixteen cases (84.2%) were improved or cured. Misdiagnosis is common due to the nonspecificity of clinical and imaging presentations of pulmonary nocardiosis. The timely combination of mNGS represents a promising approach to enhance the diagnosis of pulmonary nocardiosis and inform targeted antimicrobial therapy. TMP-SMZ is the first line of treatment. Full article

Nocardia spp. is an environmental Gram-positive bacterium able to cause infections in humans, predominantly of an opportunistic nature. Nocardial brain abscesses are rare and result from dissemination from another primary lesion, mainly observed in immunocompromised hosts. The diagnosis of nocardiosis relies on direct examination and bacterial culture, but antimicrobial susceptibility testing (AST) remains controversial due to technical challenges, limited standardization, and a paucity of studies correlating in vitro susceptibility with clinical efficacy. Management is challenging and usually based on expert opinion, as robust evidence is limited. In this case report, we describe an immunocompromised patient with a Nocardia farcinica brain abscess who achieved clinical resolution following combination therapy that included ceftriaxone, despite in vitro resistance, illustrating the complexities in interpreting AST and guiding treatment decisions in rare infections. Full article

Cutaneous nocardiosis is an uncommon bacterial infection caused by Nocardia spp.; Nocardia brasiliensis is the agent involved in most cases. This infection is acquired through the direct traumatic inoculation of soil, plants, or other substrates where the bacteria are found. Clinically, it usually manifests as an erythematous ulcerated nodule. In one-third of cases, nodules or gummas are distributed over the lymphatic pathways that resemble lymphocutaneous sporotrichosis. Its manifestations vary and can present acutely or more frequently with a latent clinical picture over time. Diagnosis is established mainly by Gram staining, biopsy, exudate culture, and molecular biology. Nocardia infections can recur, implying that antimicrobial therapy must be prolonged (between 6 and 12 months) and involve monitoring patients for at least 6 months after the end of treatment. Early diagnosis and targeted treatment may reduce patient mortality rates. We report the case of an 82-year-old woman who presented with four nodules with a lymphangitic spread on her left hand and forearm, one week after the trauma. Molecular identification was performed using 16S rDNA gene sequencing, and Nocardia brasiliensis was identified. Full article

Background and Objectives: Actinomycosis is a rare chronic contagion caused by Actinomyces spp. known for its ability to mimic malignant processes across various anatomical locations. Its clinical presentation can often resemble malignancies, Mycobacterium tuberculosis infections, nocardiosis, fungal infections, or other granulomatous diseases. This case series presents three patients diagnosed with Actinomyces spp., highlighting the diagnostic challenges and diverse clinical manifestations of the disease. Materials and Methods: We reviewed the clinical course, diagnostic procedures, and treatment outcomes of three patients with confirmed Actinomyces spp. The first case involved a 51-year-old male with a history of rhabdomyosarcoma in remission who presented with dysphagia. Magnetic resonance imaging identified an irregularly enhancing mass in the tonsil, and subsequent tonsillectomy confirmed Actinomyces spp. The second patient, an 80-year-old female, presented with dysphagia and a sublingual mass initially suspected to be diffuse large B-cell non-Hodgkin lymphoma; however, a histopathological analysis confirmed Actinomyces spp. The third case involved a 72-year-old male with abdominal pain and an ulcerated gastric lesion, where subtotal gastrectomy and histopathological examination confirmed the diagnosis of Actinomyces spp. Results: These three cases highlight the ability of Actinomyces spp. to closely mimic malignant lesions, which significantly complicates the diagnostic process. Although personalized interventions were required for each patient, diagnoses were ultimately confirmed through histopathology. Despite these challenges, timely recognition and appropriate treatment were achieved, underscoring the need to consider Actinomyces spp. in the differential diagnosis of similar presentations. Conclusions:Actinomyces spp. remains a diagnostic challenge due to its ability to mimic a variety of malignant and contagion conditions. This case series emphasizes the need for a thorough histopathological examination and a high index of suspicion when encountering lesions with atypical presentations. Given the potential for misdiagnosis, awareness and consideration of Actinomyces spp. are crucial in the differential diagnosis of chronic contagion and mass lesions. Further studies are warranted to refine diagnostic and therapeutic approaches. Full article

Few studies have focused on the infectious complications in kidney transplant recipients in tropical regions, particularly in the Caribbean. The primary objective of this study was to determine the incidence of bacterial, fungal, and parasitic infections in kidney transplant recipients in the French Caribbean and French Guiana. We included all patients who received a kidney transplant at the University Hospital of Guadeloupe between January 2014 and October 2016, with post-transplant follow-up in the French Caribbean. A total of 91 patients were included, of whom 57 developed an infectious event during follow-up. When infections were documented (94/111), bacterial infections were the most frequent (79/94), followed by fungal (11/94) and parasitic infections (4/94). Four cases of nocardiosis were identified (4/79). Phaeohyphomycosis was the most common fungal infection (7/11). In a multivariate analysis, the female gender and diabetes mellitus at the time of transplant were significantly associated with a higher risk of infection. This study is the first to describe the epidemiology of infections in kidney transplant recipients in the Caribbean and to analyze the potential risk factors. We reported a similar profile of bacterial infections to that which were observed in the European and American studies. However, we found a higher incidence of tropical infections, such as nocardiosis and phaeohyphomycosis, which highlights the need for heightened awareness among healthcare teams to ensure earlier and more appropriate treatment. Further studies focusing on these rare tropical infections are necessary to better understand their risk factors Full article

Solid organ transplant recipients (SOTRs) are at an increased risk of nocardiosis, a rare but life-threatening opportunistic infection. Universal PCP prophylaxis with trimethoprim–sulfamethoxazole (TMP-SMX) is used at our center, which is active in vitro against most species of the Nocardia genus and may have a role in preventing early infections. This is a single-center retrospective cohort study of nocardiosis in adult SOTRs at a large transplant center between January 2012 and June 2022, with comprehensive review of literature. Out of 6179 consecutive cases, 13 (0.2%) were diagnosed with nocardiosis. The patients were predominantly male (76.9%) and kidney transplant recipients (62%). Infection was diagnosed at median of 8.8 months (range, 3.7–98) after transplant. Patients were followed for a median of 457 days (range 8–3367). Overall mortality within one year after diagnosis was 46% (6/13), of which 17% (1/6) of deaths was attributable to Nocardia infection. No recurrence was reported. Nocardia infections were noted in a small proportion of our SOTRs and carried significant morbidity and mortality. TMP-SMX prophylaxis may be protective in some cases given low incidence of cases. Full article

Pseudopropionibacterium propionicum (P.p.) is an anaerobic, Gram-positive, branching beaded rod that is a component of the human microbiome. An infection of the thoracic cavity with P.p. can mimic tuberculosis (TB), nocardiosis, and malignancy. We present a case of a 77-year-old male who presented with dyspnea and a productive cough who was initially misdiagnosed with TB based on positive acid-fast staining of a pleural biopsy specimen and an elevated adenosine deaminase level of the pleural fluid. He was then diagnosed with nocardiosis based on the Gram stain of his pleural fluid that showed a Gram-positive beaded and branching rod. The pleural fluid specimen was culture-negative, but the diagnosis of thoracic P.p. infection was determined with next-generation sequencing (NGS). The patient was initially treated with imipenem and minocycline, then ceftriaxone and minocycline, and later changed to minocycline only. This report shows the utility of NGS in making a microbiological diagnosis when other techniques either failed to provide a result (culture) or gave misleading information (histopathologic exam, pleural fluid adenosine deaminase determination, and organism morphology on Gram stain). Full article

Nocardia crassostreae is a novel pathogen responsible for infections in oysters (Crassostrea gigas) and mussels (Mytilus galloprovincialis). N. crassostreae is also responsible for nocardiosis both in immunocompetent and immunocompromised patients. We investigated N. crassostreae DNA in mussels grown in marine sites of the Mediterranean Sea in the Campania Region. We examined 185 mussel pooled samples by droplet digital PCR (ddPCR) and real-time quantitative PCR (qPCR), each pool composed of 10 mussels and 149 individual mussels. ddPCR detected N. crassostreae DNA in 48 mussel pooled samples and in 23 individual mussel samples. qPCR detected N. crassostreae DNA in six pooled samples and six individual mussel samples. The two molecular assays for the detection of N. crassostreae DNA showed significant differences both in the pooled and in individual samples. Our study demonstrated that ddPCR outperformed real-time qPCR for N. crassostreae DNA detection, thus confirming that ddPCR technology can identify the pathogens in many infectious diseases with high sensitivity and specificity. Furthermore, in individual mussels showing histological lesions due to N. crassostreae, the lowest copy number/microliter detected by ddPCR of this pathogen was 0.3, which suggests that this dose could be enough to cause infections of N. crassostreae in mussels. Full article

Background. Nocardia is a group of ubiquitous bacteria known to cause opportunistic infections in immunocompromised hosts, including those affected by malignancies and solid-organ or hematopoietic stem cell transplants. Pulmonary involvement, occurring in two-thirds of cases, is the most frequent presentation. Diagnosis might be challenging both because of microbiological technical issues, but also because of the variability of organ involvement and mimicry. Methods. We describe four cases of disseminated nocardiosis caused by N. farcinica observed between September 2021 and November 2021 in immune-compromised hosts presenting with nodular cutaneous lesions that had raised a high degree of clinical suspect and led to microbiological identification through MALDI-TOF MS. Results. Cutaneous involvement is typically reported in immunocompetent hosts with primary cutaneous nocardiosis with multiple forms of manifestation; nonetheless, disseminated nocardiosis rarely involves the skin and subcutaneous tissues, and this occurs as a result of metastatic spread. Our cases were disseminated nocardiosis in which the metastatic cutaneous involvement, even if rare, provided a clue for the diagnosis. Conclusions. The pathomorphosis of disseminated nocardiosis may have changed in the current years with more rapid spread due to advanced immunosuppression. For this reason, after clinical suspicion, the prompt start of an active targeted therapy based on rapid microbiological identification might potentially open the way to hopeful results, even in the most immune-compromised patients. Full article

Systemic nocardiosis due to Nocardia farcinica has not been reported in canine outbreaks. Two 14-week-old female Dogue de Bordeaux siblings presented with fever and severe, acute onset limb lameness; traumatic lesions with evidence of infection were identified over the lame limbs of both dogs. The patients were euthanised owing to lack of therapeutic response and rapid escalation to systemic infection with central nervous system manifestations. The post-mortem changes consisted of multiple disseminated abscesses, mainly affecting the skin and subcutis at the limb traumatic injuries, local and hilar lymph nodes, lung, kidney and brain. Bacterial culture and identification via MALDI-TOF and 16S rRNA sequencing revealed Nocardia farcinica from several of these sites in both dogs. Clinical significance of the isolate was supported by cytology of the post-mortem organs’ impression smears showing numerous branching filamentous bacteria associated with inflammation. The organism displayed marked multidrug-resistance. No history of immunosuppression was available, and immunohistochemistry ruled out viral pathogens as canine distemper and parvovirus. N. farcinica should be considered as a potential differential cause of sudden lameness and systemic infection in dogs with traumatic skin lesions over the limbs. This is the first reported small-scale outbreak of systemic nocardiosis in dogs due to N. farcinica. Full article

Cutaneous nocardiosis is a rare bacterial infection that can result in various dermatologic manifestations such as actinomycetoma, lymphocutaneous infection, superficial skin infection, and secondary infection due to hematogenous dissemination. We report on a Chinese patient with erythema nodosum-like exanthema, possibly secondary to nocardiosis. Our diagnosis for this patient was based on the clinical presentation, histopathological evidence, and microbiological findings. Given the protean manifestation of Nocardia, persistent reports on new presentations of the disease are important for early identification and treatment. Full article

The identification and antimicrobial susceptibility of Nocardia spp. are essential for guiding antibiotic treatment. We investigated the species distribution and evaluated the antimicrobial susceptibility of Nocardia species collected in southern Taiwan from 2012 to 2020. A total of 77 Nocardia isolates were collected and identified to the species level using multi-locus sequence analysis (MLSA). The susceptibilities to 15 antibiotics for Nocardia isolates were determined by the broth microdilution method, and the MIC₅₀ and MIC₉₀ for each antibiotic against different species were analyzed. N. cyriacigeorgica was the leading isolate, accounting for 32.5% of all Nocardia isolates, and the prevalence of Nocardia isolates decreased in summer. All of the isolates were susceptible to trimethoprim/sulfamethoxazole, amikacin, and linezolid, whereas 90.9% were non-susceptible to cefepime and imipenem. The phylogenic tree by MLSA showed that the similarity between N. beijingensis and N. asiatica was as high as 99%, 73% between N. niigatensis and N. crassostreae, and 86% between N. cerradoensis and N. cyriacigeorgica. While trimethoprim/sulfamethoxazole, amikacin, and linezolid remained fully active against all of the Nocardia isolates tested, 90.9% of the isolates were non-susceptible to cefepime and imipenem. Full article

Nocardia farcinica is an opportunistic pathogen that causes nocardiosis primarily in patients with compromised immune systems. In this study, we used the genetically tractable organism Caenorhabditis elegans as a model to study the innate immune responses to N. farcinica infection. We found that unlike other pathogenic bacteria such as Pseudomonas aeruginosa and Staphylococcus aureus, N. farcinica failed to kill adult worms. In another words, adult worms exposed to N. farcinica exhibited a normal lifespan, compared with those fed the standard laboratory food bacterium Escherichia coli OP50. Interestingly, deletion of three core genes (pmk-1, nsy-1 and sek-1) in the p38 MAPK/PMK-1 pathway reduced the survival of worm exposure to N. farcinica, highlighting a crucial role of this pathway for C. elegans in resistance to N. farcinica. Furthermore, our results revealed that N. farcinica exposure up-regulated the level of PMK-1 phosphorylation. The activation of PMK-1 promoted nuclear translocation of a transcription factor SKN-1/Nrf2, which in turn mediated N. farcinica infection resistance in C. elegans. Our results provide an excellent example that the integrity of immune system is key aspect for counteract with pathogenesis of N. farcinica. Full article