What is Fusarium?
Fusarium is a fungus commonly found in soil and on plants. It can cause diseases in plants animals and humans [1, 2, 3].
In humans, Fusarium causes local and systemic infections. The fungi affect particularly immune-compromised individuals.
Fusarium is transmitted through the environment, such as hospitals or residences. The fungi is found in drain outlets, which allows it to spread via droplets [4].
What kind of infections does Fusarium cause?
Fusarium, especially in immunocompromised patients, causes:
Onychomycosis is an infection of the nails. It leads to thickening, discoloration, and distortion of the nails [5, 8].
Skin infections caused by Fusarium can also affect immunocompetent humans. They are characterized by painful red nodules and thick, warty skin lesions or ulcers [6, 9].
Fusariosis is an invasive and disseminated infection caused by Fusarium. It can affect multiple sites, such as the blood, liver, skin, spleen, and nervous system. This infection is linked to high mortality rates [7, 10, 11].
In rare cases, Fusarium can cause other types of infections like sinusitis, pneumonia, septic arthritis, endophthalmitis, osteomyelitis, cystitis, and brain abscesses [12, 8].
What is Listeria?
Listeria monocytogenes is a rod-shaped, Gram-positive bacterium found in dust, water, soil, animal feces, and raw meat [13, 14, 15, 16]. This bacterium has great survival skills. It can survive in extreme conditions such as low and freezing temperatures [17]. Thanks to this ability, Listeria spreads easily via contaminated foods such as unpasteurized dairy products [15, 17].
Listeria causes listeriosis, a dangerous disease for a particularly high-risk group of people. These at-risk groups include pregnant women, immunocompromised individuals, and older individuals (above 65 years) [18, 17]. In these high-risk patients, between 20% - 30% of listeriosis from food may be fatal [14, 18].
How is Listeria transmitted?
Among people, Listeria monocytogenes spreads primarily by contaminated food [19]
Foods typically linked to listeriosis are raw vegetables, unpasteurized milk products, smoked seafood, and deli meats [19].
Listeria has been found to contaminate food through fertilization with raw manure from unexamined animals. For example, in 1981, an outbreak of listeriosis in the Canadian Maritime provinces was caused by coleslaw contaminated with Listeria. This salad dish was made from cabbage fertilized with raw sheep manure [20].
The bacteria can also spread from person to person, although this is less common. Also, newborns of women infected during pregnancy have a high chance of contracting Listeria from the mother [17].
What disease does Listeria cause?
Listeria infection can cause listeriosis. This infection can range from mild to severe and is most dangerous for those who belong to the high-risk group.
In healthy people, listeriosis may present as a flu-like disease or have no symptoms at all. Nevertheless, severe cases can cause sepsis and meningoencephalitis [21, 22].
In pregnant women, listeriosis can cause severe complications, ranging from premature delivery to fetal loss and neonatal infection. Infection of the unborn child can be fatal [21, 17].
How are Fusarium and Listeria infections diagnosed?
Fusarium
One common method for diagnosing Fusarium is finding the presence of hyaline hyphae in tissue, necrotic lesions in the skin, and positive blood tests indicating fungal growth [23].
Suspicions of fungal infections can be confirmed with molecular diagnostics like multi-locus sequencing and quantitative PCR (qPCR) [23, 24].
Listeria
In contrast, Listeria infections are usually confirmed by a culture. The bacteria can be grown for up to 48 hours, but the culture allows for a definitive diagnosis. The culture sample is taken from the blood [15].
What are the treatments for Fusarium and Listeria infections?
Fusarium
Fusarium infections are challenging to treat. They often occur in immunocompromised patients, and these fungi are highly resistant to antifungal drugs. The primary treatment for Fusarium includes amphotericin B and voriconazole. Pharmacological thearpy is often combined with surgical debridement and immunosuppression treatment [25].
In some cases, terbinafine combination with amphotericin B has been used successfully in the treatment [26].
Other treatments include posaconazole, a salvage therapy for invasive fusariosis [27], and natamycin [28].
Listeria
Listeria infections are bacterial, so the main treatment is antibiotics. The drug of choice is ampicillin, which can be combined with gentamicin. In cases of allergies to ampicillin, alternatives are trimethoprim/sulfamethoxazole, erythromycin, vancomycin, and fluoroquinolones [29].
Severe cases of listeriosis may require hospitalization and intravenous antibiotic therapy [30].