Nocardiosis: Clinical Characteristics and Antimicrobial Management

Nocardiosis is an opportunistic infection caused by aerobic, branching, filamentous bacteria of the genus Nocardia, which are found ubiquitously in soil and water. Clinical presentations range from isolated pulmonary disease—often mimicking tuberculosis or malignancy—to cutaneous and disseminated forms with central nervous system involvement. Immunocompromised patients, notably those receiving high‐dose corticosteroids, solid‐organ or haematopoietic transplants, or chemotherapy, bear the highest burden, although cases in apparently immunocompetent individuals are increasingly recognised. Diagnosis relies on a combination of culture, molecular sequencing and emerging mass‐spectrometry techniques, yet remains delayed by slow growth and non‐specific radiological features. First‐line therapy traditionally comprises trimethoprim–sulfamethoxazole, frequently in combination with agents such as amikacin, meropenem or imipenem for severe or disseminated disease. Linezolid has emerged as a potent oral alternative with broad activity. Treatment durations extend from six months for isolated pulmonary disease to twelve months or more for disseminated or central nervous system infection. Management challenges include species‐level identification, variable susceptibility profiles, risk of relapse and drug toxicity, underscoring the need for tailored antimicrobial regimens and prolonged follow‐up.

Research from Nature Portfolio

Analyses of standard and clinical Nocardia isolates using microplate viability assays have reaffirmed high susceptibility to trimethoprim–sulfamethoxazole, linezolid, amikacin and meropenem, while resistance to first‐line therapy remains uncommon but species‐specific. These data have extended the antimicrobial spectrum profile to include less‐studied agents and have defined new resistance phenotypes, guiding species‐tailored regimens. Complementary multilocus sequence studies have mapped the genetic diversity of clinical Nocardia species across multiple centres, correlating sequence types with distinct susceptibility patterns. This work has cemented the value of precise molecular identification in predicting antimicrobial response and informing empirical therapy in regions with diverse Nocardia populations.

Nocardiosis: Clinical Characteristics and Antimicrobial Management publication trend

The graph below shows the total number of articles in nocardiosis: clinical characteristics and antimicrobial management across all publications each year (not limited to Nature Index journals).

Technical terms

Nocardiosis: Infection caused by Nocardia spp., presenting as pulmonary, cutaneous or disseminated disease.

Disseminated infection: Spread of Nocardia beyond the primary site, commonly involving the central nervous system.

Prophylaxis: Preventive use of antimicrobial agents to reduce the risk of infection in high‐risk patients.

Antimicrobial susceptibility testing: Laboratory methods to determine the sensitivity of Nocardia isolates to specific antibiotics.

Virulence factor: Bacterial component that enhances pathogenicity, such as proteins triggering host inflammatory pathways.

References

1. Trimethoprim-sulfamethoxazole significantly reduces the risk of nocardiosis in solid organ transplant recipients: systematic review and individual patient data meta-analysis. Clinical Microbiology and Infection (2023).
2. Activation of NF-κB/MAPK signaling and induction of apoptosis by salicylate synthase NbtS in Nocardia farcinica promotes neuroinflammation development. mSystems (2024).
3. Rapid, Easy, and Reliable Identification of Nocardia sp. by MALDI-TOF Mass Spectrometry, VITEK®-MS IVD V3.2 Database, Using Direct Deposit. International Journal of Molecular Sciences (2023).
4. Epidemiology and Antimicrobial Resistance Profiles of the Nocardia Species in China, 2009 to 2021. Microbiology Spectrum (2022).
5. Susceptibility profiles of Nocardia spp. to antimicrobial and antituberculotic agents detected by a microplate Alamar Blue assay. Scientific Reports (2017).
6. Genetic diversity and antimicrobial susceptibility of Nocardia species among patients with nocardiosis. Scientific Reports (2015).