Invasive Nocardiosis in Transplant and Nontransplant Patients: 20-Year Experience in a Tertiary Care Center

Clinical and Radiological Characterization of Central Nervous System Involvement in Nocardiosis: A 20-Year Experience

Background This study aimed to present the clinical and radiological characteristics and the outcomes of patients with Nocardia infection of the central nervous system (CNS). Methodology We conducted a retrospective review of patients aged 18 and older admitted between August 1998 and November 2018 with culture-proven nocardiosis and CNS involvement. Results Out of 110 patients with nocardiosis, 14 (12.7%) patients had CNS involvement. The median age was 54.5 (27, 86) years, and 12 (85.7%) patients were male. Overall, 12 (85.7%) patients were immunosuppressed on high doses of glucocorticoids; seven (50%) patients were solid organ transplant recipients. Only eight (57.1%) patients had neurological symptoms at presentation, and the rest were diagnosed with CNS involvement after imaging surveillance. Three distinct radiologic patterns were identified, namely, single or multiple abscesses, focal cerebritis, and small, septic embolic infarcts. All isolates of Nocardia were susceptible to trimethoprim/sulfamethoxazole and amikacin, with susceptibility to linezolid and carbapenems being 90.9% and 79.5%, respectively. Despite receiving antibiotic therapy, six (42.8%) patients died, most of them within weeks of initial admission. All surviving patients underwent prolonged antimicrobial therapy until the resolution of MRI abnormalities. All solid organ transplant recipients recovered. Conclusions Nocardia CNS infection was a rare condition, even among a large, immunosuppressed patient population. CNS imaging surveillance is paramount for immunosuppressed patients with nocardiosis, as CNS involvement influences the choice and duration of therapy. Nocardia antibiotic susceptibility varied widely between strains and the empiric therapy should consist of multiple classes of antimicrobials with CNS penetration. Mortality was high, but all solid organ transplant recipients recovered.

Invasive Nocardia Infections across Distinct Geographic Regions, United States

We reviewed invasive Nocardia infections in 3 noncontiguous geographic areas in the United States during 2011–2018. Among 268 patients with invasive nocardiosis, 48.2% were from Minnesota, 32.4% from Arizona, and 19.4% from Florida. Predominant species were N. nova complex in Minnesota (33.4%), N. cyriacigeorgica in Arizona (41.4%), and N. brasiliensis in Florida (17.3%). Transplant recipients accounted for 82/268 (30.6%) patients overall: 14 (10.9%) in Minnesota, 35 (40.2%) in Arizona, and 33 (63.5%) in Florida. Manifestations included isolated pulmonary nocardiosis among 73.2% of transplant and 84.4% of non–transplant patients and central nervous system involvement among 12.2% of transplant and 3.2% of non–transplant patients. N. farcinica (20.7%) and N. cyriacigeorgica (19.5%) were the most common isolates among transplant recipients and N. cyriacigeorgica (38.0%), N. nova complex (23.7%), and N. farcinica (16.1%) among non–transplant patients. Overall antimicrobial susceptibilities were similar across the 3 study sites.

Clinical manifestations and outcome of nocardiosis and antimicrobial susceptibility of Nocardia species in southern Taiwan, 2011-2021

BACKGROUND/PURPOSE

Nocardiosis is an uncommon infectious disease. This study aimed to assess the clinical outcome of patients with nocardiosis and examine the antimicrobial susceptibility profiles of Nocardia spp. isolated.

METHODS

We retrospectively reviewed the medical records of all inpatients diagnosed with nocardiosis between 2011 and 2021. The identification of Nocardia spp. at the species level was performed with the use of MALDI-TOF and 16S rRNA assays. The antimicrobial susceptibility of Nocardia spp. was performed using the microbroth dilution method. Factors associated with 90-day all-cause mortality were identified in multivariate logistic regression analysis.

RESULTS

Of 60 patients with nocardiosis in the 11-year study period, the lungs (55.0%) were the most common site of involvement, followed by the skin and soft tissue (45.0%). Twenty-two patients (36.7%) died within 90 days following the diagnosis. All of the Nocardia isolates were susceptible to trimethoprim-sulfamethoxazole, linezolid, and amikacin, whereas more than 70% of the isolates were not susceptible to ciprofloxacin, imipenem-cilastatin, moxifloxacin, cefepime, and clarithromycin. Nocardiosis involving the lungs (relative risk [RR], 9.99; 95% confidence interval [CI], 1.52-65.50; p = 0.02), nocardiosis involving the skin and soft tissue (RR, 0.15; 95% CI, 0.02-0.92; p = 0.04), and treatment with trimethoprim-sulfamethoxazole (RR, 0.14; 95% CI, 0.03-0.67; p = 0.01) were independently associated with 90-day all-cause mortality.

CONCLUSIONS

Nocardia spp. identified between 2011 and 2021 remained fully susceptible to trimethoprim-sulfamethoxazole, linezolid, and amikacin. Nocardiosis of the lungs, skin and soft tissue infection, and treatment with trimethoprim-sulfamethoxazole were independently associated with 90-day all-cause mortality.

Invasive Nocardiosis Versus Colonization at a Tertiary Care Center: Clinical and Radiological Characteristics

Objective

To describe the clinical and radiographic findings in a large cohort of patients with positive cultures for Nocardia emphasizing the differences between invasive disease and colonization.

Patients and Methods

We conducted a single-center, retrospective cohort study of 133 patients with a positive Nocardia isolate between August 1, 1998, and November 30, 2018, and a computed tomography (CT) of the chest within 30 days before or after the bacteria isolation date.

Results

Patients with colonization were older (71 vs 65 years; P=.004), frequently with chronic obstructive pulmonary disease (56.8% vs 16.9%; P<.001) and coronary artery disease (47.7% vs 27%, P=.021), and had Nocardia isolated exclusively from lung specimens (100% vs 83.1%; P=.003). On CT of the chest, they had frequent airway disease (84.1% vs 51.7%; P<.001). Patients with invasive nocardiosis had significantly (P<.05) more diabetes, chronic kidney disease, solid organ transplant, use of corticosteroids, antirejection drugs, and prophylactic sulfa. They had more fever (25.8% vs 2.3%; P<.001), cutaneous lesions (14.6% vs 0%; P=.005), fatigue (18% vs 0%; P=.001), pulmonary nodules (52.8% vs 27.3%; P=.006), and free-flowing pleural fluid (63.6% vs 29.4%; P=.024). The patterns of nodule distribution were different-diffuse for invasive nocardiosis and peribronchiolar for Nocardia colonization.

Conclusion

The isolation of Nocardia in sputum from a patient with respiratory symptoms does not equal active infection. Only by combining clinical and chest CT findings, one could better differentiate between invasive nocardiosis and Nocardia colonization.

Disseminated Nocardia paucivorans Infection Resembling Metastatic Disease in a Kidney Transplant Recipient

Recipients of solid-organ transplants (SOT) or hematopoietic stem-cell transplants are prone to various complications, including serious infections. Nocardiosis is an opportunistic bacterial infection that primarily affects the lung. It may also cause skin and soft-tissue infection, cerebral abscess, bloodstream infection, or infection involving other organs. We present a case of an immunocompromised kidney transplant recipient who experienced a prolonged history of unexplained indolent constitutional symptoms without a fever. Initial radiographic findings were suggestive of metastatic disease at multiple sites. However, metagenomic next-generation sequencing of microbial cell-free DNA in blood revealed disseminated Nocardia paucivorans infection, and organisms consistent with Nocardia were identified on histopathology of a lung biopsy. It is crucial for healthcare providers to be aware of unusual opportunistic infections to provide appropriate workups and interventions for immunocompromised SOT recipients.

Recurrent nocardiosis in solid organ transplant recipients: An evaluation of secondary prophylaxis

BACKGROUND

Immunocompromised individuals are at risk for Nocardia infection, with a recurrence rate of approximately 5%. Solid organ transplant (SOT) recipients often receive secondary prophylaxis due to their requirement of lifelong immunosuppression. However, data supporting this practice is sparse. We sought to evaluate Nocardia recurrence in SOT recipients, specifically evaluating secondary prophylaxis.

METHODS

We conducted a retrospective cohort study of SOT recipients diagnosed with nocardiosis from 2000 through 2020. We included adult SOT recipients who completed their course of Nocardia therapy and had at least 6 months of posttherapy follow-up. The primary outcome was Nocardia recurrence, which included relapse and reinfection.

RESULTS

One hundred two patients met inclusion criteria. Sixty-six (64.7%) were male and mean age was 58.6 ± 11.7 years. Most common SOT types were kidney (46.1%), heart (18.6%), kidney-pancreas (11.8%), and lung (10.8%). Most common sites of infection were lung (85.3%), skin (17.6%), and brain (14.7%). Secondary prophylaxis was utilized in 53 (52.0%) patients. Trimethoprim-sulfamethoxazole (TMP-SMX) single-strength daily was the most common prophylaxis agent and dose. Five patients (4.9%) experienced Nocardia recurrence, three of which were receiving secondary prophylaxis at time of recurrence. Two recurrences were with the same Nocardia species. Factors associated with recurrence were lung transplantation (p = .011), chronic lung disease (p = .032), and treatment ≤120 days (p = .006). Time from treatment completion to recurrence ranged from 107 to 875 days.

CONCLUSIONS

Nocardia recurrence in SOT recipients is an uncommon event. TMP-SMX secondary prophylaxis is incompletely protective and recurrence may be dependent upon other factors. Further study of secondary prophylaxis is warranted.

Cladophialophora bantiana and Nocardia farcinica infection simultaneously occurring in a kidney transplant recipient: Case report and literature review

Solid organ transplant recipients are at increased risk of acquiring devastating infections with unusual pathogens. Nocardia are aerobic actinomycetes that affect the lungs, brain, skin and soft tissue. Cladophialophora species are dematiaceous fungi that overwhelmingly cause infections in the brain. Both organisms carry a high mortality rate. We present the first reported renal transplant case with Cladophialophora bantiana involving the renal allograft with concurrent invasive nocardiosis involving the lungs and brain.