Nocardia niwae, a new bacteria in the Nocardia group, has become an opportunistic pathogen causing human infections. It was first found in 2011 from a lung cancer patient in Japan. N. niwae shouldn’t be underestimated as it causes widespread nocardiosis disease. 

One case was a 63-year-old woman with lung cancer. She had a severe Nocardia niwae infection in her lungs and brain. These infections may lead to death in people with weakened immune systems. 

Though only recently recognized as a human pathogen, N. niwae habitats all environments like dirt, decaying plants, freshwater, and saltwater. Its widespread presence suggests humans can easily get exposed to the environment. N. niwae survives and multiplies almost anywhere, providing many sources of possible infection. 

Nocardia niwae is part of the Nocardiaceae family and Actinomycetia class. Its colonies vary greatly. Under a microscope, most species in this genus have noticeable aerial hyphae, used to identify Nocardia colonies. 

N. niwae grows slowly, like other Nocardia species, especially on non-selective media. As an obligate aerobe, it needs oxygen to thrive, preferring aerobic conditions. Its growth involves branching mycelia and substrate hyphae fragmenting into non-motile rods.

Nocardia niwae utilizes catalase and Superoxide Dismutase as crucial enzymatic defenses. These enzymes neutralize reactive oxygen species and shield the bacterium from oxidative damage, helping it survive oxidative stress. 

Genomic analysis of a clinical N. niwae sample revealed interesting molecular details. Antimicrobial resistance genes like mtrA, RbpA, FAR-1, blaFAR-1, and rox were identified, giving insights into its drug resistance. Simultaneously, virulence genes such as relA, icl, and mbtH were detected, showing its pathogenic potential. Apart from resistance genes, susceptibility testing, showed the strain’s sensitivity to imipenem, linezolid, and trimethoprim-sulfamethoxazole. 

The type strain of N. niwae, W9241T, also known as DSM 45340, CCUG 57756, JCM 19118, & NBRC 108934, provides a reference for studying this clinically significant bacterium. 

Nocardia niwae is a microbe that leads to suppurative diseases. These can be localized or spread. One notable characteristic of Nocardia spp. is its ability to disseminate. It can infiltrate virtually any organ, especially the central nervous system. Despite treatment, nocardiosis frequently relapses or progresses. 

The environmental sources of N. niwae pose infection risks. It is found in standing water, decaying plants, and soil. Inhalation of dust with Nocardia can result in lung infections. Traumatic inoculation occurs when soil or water carrying Nocardia enters cuts or scrapes. 

In healthcare settings, hospital-acquired infections are possible. Patients may be exposed through contaminated equipment or post-surgery wounds. Notably, the CNS is a common site for disseminated nocardiosis. The severity is underscored by mortality rates, particularly in brain or spinal cord involvement cases. Up to 44% of patients with such CNS infections die from the disease. The mortality risk is higher in severely immunocompromised individuals. 

Phagocytes, like neutrophils and macrophages, act as front-line defenders. They gobble up and remove Nocardia niwae, kick-starting the immune response against this bacterium. 

Antimicrobial peptides Human β-Defensin (hBD)-3, Human α-Defensins 1-3 (HNPs), and Cathelicidin LL-37 play a crucial role. They directly target and are effective against Nocardia niwae in the early defense stages. These human AMPs boost the host’s ability to combat bacterial invasion. 

The immune response includes cytokines and chemokines, signaling molecules, summon immune cells to the infection site. Inflammation is promoted. Through this coordinated response, the spread of Nocardia niwae is effectively contained. 

The complement system is a versatile defense mechanism. It either directly kills bacteria or coats for enhanced phagocytosis. In chronic infections, the host may form granulomas which is organized immune cell clusters containing the persistent N. niwae infection. 

Nocardia niwae can cause nocardiosis. It is a rare bacterial infection. Nocardiosis affects many parts of the body, especially the brain. It often infects people with weak immune systems. Nocardiosis has primary forms: lung disease, brain infection, skin problems, and widespread disease. 

Lung disease from N. niwae may look like pneumonia. Symptoms are fever, weight loss, coughing, night sweats, and chest pain. The lungs get infected, causing trouble breathing and other lung symptoms. 

With brain infection, people can get headaches, confusion, weakness, and seizures. Nocardia niwae infects the brain and nervous system. It causes neurological problems. 

On the skin, there are lesions and abscesses. The bacterium infects the skin and causes these skin issues. In widespread disease, nocardiosis affects many organs in the body. 

Collecting samples is vital when checking for nocardiosis infection. It depends on the infected area. For instance, get sputum, pus from abscesses, and granules, if they exist. But isolating Nocardia species won’t always mean infection. It could signal colonization or accidental lab contamination. 

When granules appear in actinomycetoma samples; Wash them, blend them into an emulsion, and apply Gram stain. Seeing gram-positive branching or partly-branching stick-like bacteria or often beaded, it suggests actinomycetes like Nocardia. 

The Kinyoun method stains samples to spot acid-fast organisms, including Nocardia. N. niwae may partially resist acid due to their unique cell walls. 

Culture samples on media like Lowenstein-Jensen medium, Sabouraud agar, or brain heart infusion agar. N. niwae grow aerobically but slowly. Once cultured, biochemical tests like catalase or urease activity, casein & tyrosine breakdown, and carbon source use help identify the species. 

Treating nocardiosis often requires long antibiotic courses, sometimes over a year, to prevent relapse. Surgery may drain abscesses or wound infections. Thorough diagnosis like this ensures proper Nocardia niwae identification and management. 

• Washing hands with soap and water is essential to stop spreading it. Healthcare workers must cover up when touching dirt, water, or other contaminants that might have nocardia. 

• Don’t breathe in dust or air contaminated with nocardia. Hospitals should have standard infection control practices to stop nocardiosis. 

• People with weak immune systems, like cancer patients & transplant recipients need to be careful. These people must watch for infection signs and get checked quickly if sick. Finding nocardiosis early and treating it fast helps avoid severe illness. 

Nocardia niwae Disseminated Nocardiosis: A Novel Species Presenting Concurrently With Lung Adenocarcinoma – PubMed (nih.gov) 

Menace Elbow: Disseminated Nocardiosis – PMC (nih.gov)